From 8cf8aaab3056fa087b2432bc625ae14d750380e9 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 19:03:48 -0800
Subject: [PATCH 01/13] update

---
 download_test_runner.sh                       |  36 ---
 test-runner/.env.example                      |   6 +
 test-runner/.github/workflows/publish.yml     |  35 +++
 test-runner/.github/workflows/tag.yml         |  29 ++
 test-runner/.github/workflows/test.yml        |  65 +++++
 test-runner/.gitignore                        |   5 +
 test-runner/.ruby-version                     |   1 +
 test-runner/Gemfile                           |  48 ++++
 test-runner/Gemfile.lock                      | 160 +++++++++++
 test-runner/Makefile                          |  65 +++++
 test-runner/README.md                         |  40 +++
 test-runner/docker-compose.yml                |  39 +++
 test-runner/go.mod                            |  36 +++
 test-runner/go.sum                            |  83 ++++++
 test-runner/internal/backend/client.go        |  63 +++++
 .../backend/create_test_run_result.go         |  41 +++
 .../internal/backend/finalize_build.go        |  39 +++
 .../internal/backend/report_shutdown.go       |  37 +++
 .../internal/backend/reserve_test_run.go      |  62 +++++
 .../backend/trigger_infrastructure_rebuild.go |  49 ++++
 test-runner/internal/build_image.go           | 109 ++++++++
 test-runner/internal/build_logs_processor.go  |  57 ++++
 .../internal/build_logs_processor_test.go     |  68 +++++
 test-runner/internal/color/color.go           |  23 ++
 .../internal/commands/build_image_command.go  | 260 ++++++++++++++++++
 test-runner/internal/friendly_error.go        |  11 +
 test-runner/internal/get_buildpack.go         |  42 +++
 test-runner/internal/get_head_commit_sha.go   |  18 ++
 .../globals/codecrafters_server_url.go        |  15 +
 .../move_app_cached_files_if_needed.go        |  24 ++
 .../internal/run_precompilation_if_needed.go  |  71 +++++
 test-runner/internal/run_tester.go            |  33 +++
 test-runner/internal/switch_to_commit.go      |  61 ++++
 test-runner/internal/test_run.go              |  78 ++++++
 test-runner/internal/test_runner_build.go     |  98 +++++++
 test-runner/internal/utils/sentry.go          |  28 ++
 test-runner/main.go                           |  23 ++
 test-runner/main.goreleaser.yml               |  11 +
 test-runner/tests/build_image_test.rb         | 168 +++++++++++
 .../tests/lib/build_image_command_runner.rb   |  63 +++++
 .../lib/buildpack_dockerfile_processor.rb     |  88 ++++++
 test-runner/tests/lib/code_fixtures.rb        |  38 +++
 test-runner/tests/lib/database_helper.rb      |  10 +
 .../tests/lib/db/models/application_record.rb |   7 +
 test-runner/tests/lib/db/models/buildpack.rb  |  15 +
 test-runner/tests/lib/db/models/repository.rb |  29 ++
 test-runner/tests/lib/db/models/submission.rb |  10 +
 test-runner/tests/lib/db/models/test_run.rb   |  28 ++
 .../tests/lib/db/models/test_run_result.rb    |  16 ++
 .../tests/lib/db/models/test_runner.rb        |  15 +
 .../tests/lib/db/models/test_runner_build.rb  |  32 +++
 test-runner/tests/lib/db/schema.rb            |  56 ++++
 test-runner/tests/lib/fake_git_repository.rb  |  90 ++++++
 test-runner/tests/lib/fake_server.rb          | 196 +++++++++++++
 test-runner/tests/lib/git_api_gateway.rb      |  43 +++
 .../tests/lib/run_tests_command_runner.rb     |  53 ++++
 .../submission_test_runner_actions_builder.rb |  62 +++++
 .../await_terminal_build_status.rb            |  17 ++
 .../await_terminal_submission_status.rb       |  17 ++
 .../tests/lib/test_runner_actions/base.rb     |  29 ++
 .../lib/test_runner_actions/print_message.rb  |  33 +++
 .../tests/lib/test_runner_actions/sleep.rb    |  18 ++
 .../lib/test_runner_actions/stream_logs.rb    |  13 +
 .../lib/test_runner_actions/terminate.rb      |  13 +
 test-runner/tests/lib/tester_downloader.rb    |  54 ++++
 test-runner/tests/run_tests_test.rb           | 198 +++++++++++++
 test-runner/tests/sample_data/docker_logs.txt | 155 +++++++++++
 test-runner/tests/test_helper.rb              |  25 ++
 68 files changed, 3524 insertions(+), 36 deletions(-)
 delete mode 100755 download_test_runner.sh
 create mode 100644 test-runner/.env.example
 create mode 100644 test-runner/.github/workflows/publish.yml
 create mode 100644 test-runner/.github/workflows/tag.yml
 create mode 100644 test-runner/.github/workflows/test.yml
 create mode 100644 test-runner/.gitignore
 create mode 100644 test-runner/.ruby-version
 create mode 100644 test-runner/Gemfile
 create mode 100644 test-runner/Gemfile.lock
 create mode 100644 test-runner/Makefile
 create mode 100644 test-runner/README.md
 create mode 100644 test-runner/docker-compose.yml
 create mode 100644 test-runner/go.mod
 create mode 100644 test-runner/go.sum
 create mode 100644 test-runner/internal/backend/client.go
 create mode 100644 test-runner/internal/backend/create_test_run_result.go
 create mode 100644 test-runner/internal/backend/finalize_build.go
 create mode 100644 test-runner/internal/backend/report_shutdown.go
 create mode 100644 test-runner/internal/backend/reserve_test_run.go
 create mode 100644 test-runner/internal/backend/trigger_infrastructure_rebuild.go
 create mode 100644 test-runner/internal/build_image.go
 create mode 100644 test-runner/internal/build_logs_processor.go
 create mode 100644 test-runner/internal/build_logs_processor_test.go
 create mode 100644 test-runner/internal/color/color.go
 create mode 100644 test-runner/internal/commands/build_image_command.go
 create mode 100644 test-runner/internal/friendly_error.go
 create mode 100644 test-runner/internal/get_buildpack.go
 create mode 100644 test-runner/internal/get_head_commit_sha.go
 create mode 100644 test-runner/internal/globals/codecrafters_server_url.go
 create mode 100644 test-runner/internal/move_app_cached_files_if_needed.go
 create mode 100644 test-runner/internal/run_precompilation_if_needed.go
 create mode 100644 test-runner/internal/run_tester.go
 create mode 100644 test-runner/internal/switch_to_commit.go
 create mode 100644 test-runner/internal/test_run.go
 create mode 100644 test-runner/internal/test_runner_build.go
 create mode 100644 test-runner/internal/utils/sentry.go
 create mode 100644 test-runner/main.go
 create mode 100644 test-runner/main.goreleaser.yml
 create mode 100644 test-runner/tests/build_image_test.rb
 create mode 100644 test-runner/tests/lib/build_image_command_runner.rb
 create mode 100644 test-runner/tests/lib/buildpack_dockerfile_processor.rb
 create mode 100644 test-runner/tests/lib/code_fixtures.rb
 create mode 100644 test-runner/tests/lib/database_helper.rb
 create mode 100644 test-runner/tests/lib/db/models/application_record.rb
 create mode 100644 test-runner/tests/lib/db/models/buildpack.rb
 create mode 100644 test-runner/tests/lib/db/models/repository.rb
 create mode 100644 test-runner/tests/lib/db/models/submission.rb
 create mode 100644 test-runner/tests/lib/db/models/test_run.rb
 create mode 100644 test-runner/tests/lib/db/models/test_run_result.rb
 create mode 100644 test-runner/tests/lib/db/models/test_runner.rb
 create mode 100644 test-runner/tests/lib/db/models/test_runner_build.rb
 create mode 100644 test-runner/tests/lib/db/schema.rb
 create mode 100644 test-runner/tests/lib/fake_git_repository.rb
 create mode 100644 test-runner/tests/lib/fake_server.rb
 create mode 100644 test-runner/tests/lib/git_api_gateway.rb
 create mode 100644 test-runner/tests/lib/run_tests_command_runner.rb
 create mode 100644 test-runner/tests/lib/submission_test_runner_actions_builder.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/base.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/print_message.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/sleep.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/stream_logs.rb
 create mode 100644 test-runner/tests/lib/test_runner_actions/terminate.rb
 create mode 100644 test-runner/tests/lib/tester_downloader.rb
 create mode 100644 test-runner/tests/run_tests_test.rb
 create mode 100644 test-runner/tests/sample_data/docker_logs.txt
 create mode 100644 test-runner/tests/test_helper.rb

diff --git a/download_test_runner.sh b/download_test_runner.sh
deleted file mode 100755
index 3c7a51c..0000000
--- a/download_test_runner.sh
+++ /dev/null
@@ -1,36 +0,0 @@
-set -e
-set -x
-
-destinationDir="/var/opt/test-runner" # Destination directory
-
-repoOwner="codecrafters-io"                  # GitHub repository owner
-repoName="test-runner"                       # GitHub repository name
-releaseTag="v0.3.67"                         # Release tag to download
-assetName="${releaseTag}_linux_amd64.tar.gz" # Asset name
-downloadedTarPath="$(mktemp)"                # Path to downloaded tar file
-
-# Get the asset ID
-assetId=$(curl -fsSL --header "Authorization: Bearer ${GITHUB_TOKEN}" "https://api.github.com/repos/$repoOwner/$repoName/releases/tags/$releaseTag" | jq -r --arg assetName "$assetName" '.assets[] | select(.name==$assetName) | .id')
-echo "Asset ID: $assetId"
-
-downloadUrl="https://api.github.com/repos/$repoOwner/$repoName/releases/assets/$assetId"
-echo "Download URL: $downloadUrl"
-
-wget --header="Authorization: Bearer ${GITHUB_TOKEN}" --header="Accept: application/octet-stream" -O $downloadedTarPath $downloadUrl
-mkdir -p $destinationDir
-tar xz -C $destinationDir -f $downloadedTarPath
-
-rm -rf $downloadedTarPath
-
-# TODO: Replace this by adding a `--version` flag!
-set +e
-output=$(/var/opt/test-runner/test-runner --help 2>&1)
-exit_code=$?
-echo "$output"
-echo "$output" | grep -qi "unknown command"
-grep_exit_code=$?
-if [ $exit_code -ne 1 ] || [ $grep_exit_code -ne 0 ]; then
-    echo "Test failed: exit code was $exit_code, output was: $output"
-    exit 1
-fi
-set -e
diff --git a/test-runner/.env.example b/test-runner/.env.example
new file mode 100644
index 0000000..e2e61cb
--- /dev/null
+++ b/test-runner/.env.example
@@ -0,0 +1,6 @@
+# An access token with access to the image we're pushing to
+FLY_ACCESS_TOKEN="FlyV1 fm2_lJPECAAAAAAAAFu1xBDrE74JtpQtL/bs+u0CJiAlwrVodHRwczovL2FwaS5mbHkuaW8vdjGWAJLNzSMfC5O5aHR0cHM6Ly9hcGkuZmx5LmlvL2FhYS92McQ8WBLmZVkPM+bp+MYa59roq4p6RFGZOPyD4t7nrtfytR5QBg98z5akYSJcTjdQTua4QzBDT++kXlJi2W27xEWjm09GHI3BdcjBvMxe2c8jiT8KYneORr3tDZU+4lSvtJPDPaOnMVgNGb7NhJBhbP5sbY3oC93TYOco5L6xYEStTEKq4xUNkpQDkYHOABtQrB8FkYKnYnVpbGRlch+id2cfAcQgU/LVB8aWvqkvnRbRKd42i//Yvd5T73HVF0WxfsZ1Xbk=,fm2_lJPERaObT0YcjcF1yMG8zF7ZzyOJPwpid45Gve0NlT7iVK+0k8M9o6cxWA0Zvs2EkGFs/mxtjegL3dNg5yjkvrFgRK1MQqrjFcQQKZ82IUHac0JAIRLvYvaGEcO5aHR0cHM6Ly9hcGkuZmx5LmlvL2FhYS92MZYEks5lqHCMzwAAAAEhoI6qCpHNTwQMxBDpPM5My6ihVldeuGRWbT4vxCCF+j8afdZU4B5W/rcGBV34Ky0zOuVErci6LlBvm+xgsA=="
+
+# A depot project & token
+DEPOT_PROJECT="jlmt2zdb5m" # test-runner-ci
+DEPOT_TOKEN="depot_project_e252ea64749beae1c983d2f95c952c892cb211c3a0e4aff1fe9ceb5bd14fc0a5"
diff --git a/test-runner/.github/workflows/publish.yml b/test-runner/.github/workflows/publish.yml
new file mode 100644
index 0000000..9285566
--- /dev/null
+++ b/test-runner/.github/workflows/publish.yml
@@ -0,0 +1,35 @@
+name: Publish
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  publish_tester:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Unshallow
+        run: git fetch --prune --unshallow
+
+      - name: Set up Go
+        uses: actions/setup-go@v1
+        with:
+          go-version: 1.21.x
+
+      # Is this needed?
+      # - run: "sudo apt-get install gcc-multilib g++-multilib"
+
+      - name: Run GoReleaser
+        uses: goreleaser/goreleaser-action@v5
+        with:
+          version: v1.21.2
+          args: release -f main.goreleaser.yml --clean
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/test-runner/.github/workflows/tag.yml b/test-runner/.github/workflows/tag.yml
new file mode 100644
index 0000000..91d6a47
--- /dev/null
+++ b/test-runner/.github/workflows/tag.yml
@@ -0,0 +1,29 @@
+name: Tag
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  create-tag:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0 # Ensure that all tags are available
+
+      - name: "Compute next version tag"
+        run: |-
+          nextVersionTag=$(make print_next_version_tag)
+          echo "next: $nextVersionTag"
+          echo "::set-output name=next_version_tag::$nextVersionTag"
+        id: compute_next_version_tag
+
+      - name: Bump version and push tag
+        uses: mathieudutour/github-tag-action@v6.2
+        with:
+          github_token: ${{ secrets.CODECRAFTERS_BOT_GITHUB_TOKEN }}
+          custom_tag: ${{ steps.compute_next_version_tag.outputs.next_version_tag }}
+          tag_prefix: ""
diff --git a/test-runner/.github/workflows/test.yml b/test-runner/.github/workflows/test.yml
new file mode 100644
index 0000000..76d4e58
--- /dev/null
+++ b/test-runner/.github/workflows/test.yml
@@ -0,0 +1,65 @@
+name: Test
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  test:
+    runs-on: ubuntu-latest-4-cores
+    timeout-minutes: 15
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - uses: depot/setup-action@v1
+
+      - name: Install logstream
+        run: |
+          curl -L https://github.com/codecrafters-io/logstream/releases/download/v0.2.2/v0.2.2_linux_amd64 -o /usr/local/bin/logstream
+          chmod +x /usr/local/bin/logstream
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: "1.21"
+
+      - name: Set up ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.3.5
+          bundler-cache: true
+          cache-version: 5
+
+      - name: Run make refresh_test_fixtures
+        run: make refresh_test_fixtures
+
+      # Required for pulling git-api and git-daemon
+      - name: Authenticate with ghcr.io
+        run: echo '${{ secrets.CI_DOCKER_AUTH_PAT }}' | docker login ghcr.io -u codecrafters-bot --password-stdin
+
+      # Required by build_image
+      - name: Authenticate with registry.fly.io
+        run: echo '${{ secrets.FLY_ACCESS_TOKEN }}' | docker login registry.fly.io -u x --password-stdin
+
+      - name: Set up Docker
+        run: docker compose up -d
+
+      - name: Set up Git
+        run: |
+          git config --global user.email "you@example.com"
+          git config --global user.name "Your Name"
+
+      - name: Run tests
+        run: make test
+        env:
+          DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
+          DEPOT_PROJECT: ${{ secrets.DEPOT_PROJECT }}
+          FLY_ACCESS_TOKEN: ${{ secrets.FLY_ACCESS_TOKEN }}
diff --git a/test-runner/.gitignore b/test-runner/.gitignore
new file mode 100644
index 0000000..ef6e102
--- /dev/null
+++ b/test-runner/.gitignore
@@ -0,0 +1,5 @@
+.vagrant/
+
+tests/fixtures/
+dist
+.env
\ No newline at end of file
diff --git a/test-runner/.ruby-version b/test-runner/.ruby-version
new file mode 100644
index 0000000..0163af7
--- /dev/null
+++ b/test-runner/.ruby-version
@@ -0,0 +1 @@
+3.3.5
\ No newline at end of file
diff --git a/test-runner/Gemfile b/test-runner/Gemfile
new file mode 100644
index 0000000..a428928
--- /dev/null
+++ b/test-runner/Gemfile
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
+
+# Test Runner
+gem "minitest"
+
+# GitHub SDK
+gem "octokit"
+
+# Debugging
+gem "pry"
+
+# Parallel processing
+gem "pmap"
+
+# Formatter
+gem "standard"
+
+# Docker SDK
+gem "docker-api"
+
+# HTTParty
+gem "httparty"
+gem "faraday-retry"
+
+# Web Server
+gem "sinatra", require: false
+gem "puma"
+
+# Database
+gem "sqlite3"
+gem "activerecord"
+
+# Spawn processes
+gem "childprocess"
+gem "tty-command"
+
+# .env files
+gem "dotenv"
+
+# Autoloading
+gem "zeitwerk"
+
+# Ending minitest tests early
+gem "minitest-fail-fast"
diff --git a/test-runner/Gemfile.lock b/test-runner/Gemfile.lock
new file mode 100644
index 0000000..4832b26
--- /dev/null
+++ b/test-runner/Gemfile.lock
@@ -0,0 +1,160 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    activemodel (7.1.1)
+      activesupport (= 7.1.1)
+    activerecord (7.1.1)
+      activemodel (= 7.1.1)
+      activesupport (= 7.1.1)
+      timeout (>= 0.4.0)
+    activesupport (7.1.1)
+      base64
+      bigdecimal
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      connection_pool (>= 2.2.5)
+      drb
+      i18n (>= 1.6, < 2)
+      minitest (>= 5.1)
+      mutex_m
+      tzinfo (~> 2.0)
+    addressable (2.8.5)
+      public_suffix (>= 2.0.2, < 6.0)
+    ast (2.4.2)
+    base64 (0.1.1)
+    bigdecimal (3.1.4)
+    childprocess (4.1.0)
+    coderay (1.1.3)
+    concurrent-ruby (1.2.2)
+    connection_pool (2.4.1)
+    docker-api (2.2.0)
+      excon (>= 0.47.0)
+      multi_json
+    dotenv (2.8.1)
+    drb (2.1.1)
+      ruby2_keywords
+    excon (0.104.0)
+    faraday (2.7.11)
+      base64
+      faraday-net_http (>= 2.0, < 3.1)
+      ruby2_keywords (>= 0.0.4)
+    faraday-net_http (3.0.2)
+    faraday-retry (2.2.0)
+      faraday (~> 2.0)
+    httparty (0.21.0)
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
+    i18n (1.14.1)
+      concurrent-ruby (~> 1.0)
+    json (2.6.3)
+    language_server-protocol (3.17.0.3)
+    lint_roller (1.1.0)
+    method_source (1.0.0)
+    mini_mime (1.1.2)
+    mini_portile2 (2.8.4)
+    minitest (5.20.0)
+    minitest-fail-fast (0.1.0)
+      minitest (~> 5)
+    multi_json (1.15.0)
+    multi_xml (0.6.0)
+    mustermann (3.0.0)
+      ruby2_keywords (~> 0.0.1)
+    mutex_m (0.1.2)
+    nio4r (2.5.9)
+    octokit (7.2.0)
+      faraday (>= 1, < 3)
+      sawyer (~> 0.9)
+    parallel (1.23.0)
+    parser (3.2.2.4)
+      ast (~> 2.4.1)
+      racc
+    pastel (0.8.0)
+      tty-color (~> 0.5)
+    pmap (1.1.1)
+    pry (0.14.2)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    public_suffix (5.0.3)
+    puma (6.4.0)
+      nio4r (~> 2.0)
+    racc (1.7.1)
+    rack (2.2.7)
+    rack-protection (3.0.6)
+      rack
+    rainbow (3.1.1)
+    regexp_parser (2.8.2)
+    rexml (3.2.6)
+    rubocop (1.56.4)
+      base64 (~> 0.1.1)
+      json (~> 2.3)
+      language_server-protocol (>= 3.17.0)
+      parallel (~> 1.10)
+      parser (>= 3.2.2.3)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.28.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.29.0)
+      parser (>= 3.2.1.0)
+    rubocop-performance (1.19.1)
+      rubocop (>= 1.7.0, < 2.0)
+      rubocop-ast (>= 0.4.0)
+    ruby-progressbar (1.13.0)
+    ruby2_keywords (0.0.5)
+    sawyer (0.9.2)
+      addressable (>= 2.3.5)
+      faraday (>= 0.17.3, < 3)
+    sinatra (3.0.6)
+      mustermann (~> 3.0)
+      rack (~> 2.2, >= 2.2.4)
+      rack-protection (= 3.0.6)
+      tilt (~> 2.0)
+    sqlite3 (1.6.7)
+      mini_portile2 (~> 2.8.0)
+    standard (1.31.2)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.56.4)
+      standard-custom (~> 1.0.0)
+      standard-performance (~> 1.2)
+    standard-custom (1.0.2)
+      lint_roller (~> 1.0)
+      rubocop (~> 1.50)
+    standard-performance (1.2.1)
+      lint_roller (~> 1.1)
+      rubocop-performance (~> 1.19.1)
+    tilt (2.2.0)
+    timeout (0.4.0)
+    tty-color (0.6.0)
+    tty-command (0.10.1)
+      pastel (~> 0.8)
+    tzinfo (2.0.6)
+      concurrent-ruby (~> 1.0)
+    unicode-display_width (2.5.0)
+    zeitwerk (2.6.12)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  activerecord
+  childprocess
+  docker-api
+  dotenv
+  faraday-retry
+  httparty
+  minitest
+  minitest-fail-fast
+  octokit
+  pmap
+  pry
+  puma
+  sinatra
+  sqlite3
+  standard
+  tty-command
+  zeitwerk
+
+BUNDLED WITH
+   2.4.20
diff --git a/test-runner/Makefile b/test-runner/Makefile
new file mode 100644
index 0000000..fa58118
--- /dev/null
+++ b/test-runner/Makefile
@@ -0,0 +1,65 @@
+current_patch_number := $(shell git tag --list "v0.3.*" | sort -V | tail -n 1 | cut -c 6-)
+next_patch_number := $(shell echo $$(($(current_patch_number)+1)))
+next_version_tag := v0.3.$(next_patch_number)
+
+# Releases are automatically created on pushes to `main`, but this can be used to manually create a release.
+release:
+	git tag $(next_version_tag)
+	git push origin main $(next_version_tag)
+
+build_linux:
+	# -mod=mod is required to ensure that go isn't confused by Ruby's vendor/bundle directory
+	# CGO_ENABLED=0 ensures that the binary is statically linked and doesn't depend on any shared libraries
+	GOOS=linux CGO_ENABLED=0 go build -mod=mod -o dist/main-linux.out ./
+
+build_native:
+	# -mod=mod is required to ensure that go isn't confused by Ruby's vendor/bundle directory
+	# CGO_ENABLED=0 ensures that the binary is statically linked and doesn't depend on any shared libraries
+	CGO_ENABLED=0 go build -mod=mod -o dist/main.out ./
+
+build: build_linux build_native
+
+print_next_version_tag:
+	@echo $(next_version_tag) | tr -d '\n'
+
+refresh_test_fixtures:
+	rm -rf ./tests/fixtures
+	mkdir -p ./tests/fixtures
+	mkdir -p ./tests/fixtures/dockerfiles
+
+	rm -rf /tmp/byo-redis
+	git clone https://github.com/codecrafters-io/build-your-own-redis /tmp/byo-redis
+	cd /tmp/byo-redis && git checkout 5ce64229f59108851de28c4f083f3459d58eff34
+
+	rm -rf /tmp/byo-sqlite
+	git clone https://github.com/codecrafters-io/build-your-own-sqlite /tmp/byo-sqlite
+	cd /tmp/byo-sqlite && git checkout 8f419979fb7b3eb95cd2d0547f084032cf9edf39
+
+	rm -rf ./tests/fixtures/redis-ruby-pass-stage-1
+	cp -R /tmp/byo-redis/solutions/ruby/01-jm1/code ./tests/fixtures/redis-ruby-pass-stage-1
+	cp /tmp/byo-redis/dockerfiles/ruby-3.3.Dockerfile ./tests/fixtures/dockerfiles/redis-ruby-3.3.Dockerfile
+
+	rm -rf ./tests/fixtures/redis-rust-pass-stage-1
+	cp -R /tmp/byo-redis/solutions/rust/01-jm1/code ./tests/fixtures/redis-rust-pass-stage-1
+	cp /tmp/byo-redis/dockerfiles/rust-1.88.Dockerfile ./tests/fixtures/dockerfiles/redis-rust-1.88.Dockerfile
+
+	rm -rf ./tests/fixtures/redis-go-pass-stage-1
+	cp -R /tmp/byo-redis/solutions/go/01-jm1/code ./tests/fixtures/redis-go-pass-stage-1
+	cp /tmp/byo-redis/dockerfiles/go-1.24.Dockerfile ./tests/fixtures/dockerfiles/redis-go-1.24.Dockerfile
+
+	rm -rf ./tests/fixtures/sqlite-python-pass-stage-1
+	cp -R /tmp/byo-sqlite/solutions/python/01-dr6/code ./tests/fixtures/sqlite-python-pass-stage-1
+	cp /tmp/byo-sqlite/dockerfiles/python-3.13.Dockerfile ./tests/fixtures/dockerfiles/sqlite-python-3.13.Dockerfile
+
+test: test_go test_run_tests test_build_image
+
+test_go:
+	# -mod=mod is required to ensure that go isn't confused by Ruby's vendor/bundle directory
+	go test -mod=mod ./...
+
+test_run_tests: build
+	bundle exec ruby tests/run_tests_test.rb --verbose --fail-fast
+
+test_build_image: build
+	bundle exec ruby tests/build_image_test.rb --verbose --fail-fast
+
diff --git a/test-runner/README.md b/test-runner/README.md
new file mode 100644
index 0000000..f5eb571
--- /dev/null
+++ b/test-runner/README.md
@@ -0,0 +1,40 @@
+# Test Runner
+
+This is the component responsible for running tests for CodeCrafters challenges.
+
+### Functionality
+
+It supports two commands:
+
+- `build_image`
+  - Builds the docker image that needs to executed to run tests for a challenge
+  - Also streams logs back to a logstream URL
+- `run_tests`
+  - Runs the tests for a challenge (this is the entrypoint of the docker image)
+  - Streams logs back to a logstream URL
+
+### Testing Locally
+
+This repository includes a fake server that can be used to test the test runner program locally.
+
+- Install Ruby & Go
+- `bundle install`
+- `make refresh_test_fixtures` (downloads sample repositories)
+- Ensure you're logged into the GitHub container registry by running this command: `docker login ghcr.io`.
+  - The username is your github username.
+  - The password is a GitHub access token with `read:packages` permissions (do **NOT** use your GitHub password here)
+- Use `flyctl auth docker` to authenticate with Fly's Docker registry
+- `docker compose up -d`
+- `make test`
+
+To run a specific test:
+
+- `bundle exec ruby tests/run_tests_test.rb --verbose -n /when_/`
+
+### Deploys
+
+- Releases are automatically created on pushes to `main`
+  - This happens via [./github/workflows/{tag,release}.yml](.github/workflows/tag.yml)
+  - It takes 2-3 minutes for a release to be created after a push to `main`.
+  - You can confirm that a release has been created by checking the [Releases](https://github.com/codecrafters-io/test-runner/releases) page.
+- Ask Paul to deploy the release (this part isn't automated yet)
diff --git a/test-runner/docker-compose.yml b/test-runner/docker-compose.yml
new file mode 100644
index 0000000..da39a44
--- /dev/null
+++ b/test-runner/docker-compose.yml
@@ -0,0 +1,39 @@
+version: '3'
+
+services:
+  # Used to serve Git repositories for cloning in tests
+  git_daemon:
+    image: ghcr.io/codecrafters-io/git-daemon/git-daemon:v59
+    # comment this out to build locally
+    # build:
+    #   context: ../git-daemon
+    environment:
+      CODECRAFTERS_SERVER_URL: "http://host.docker.internal:6331"
+    volumes:
+      - git_data:/usr/git
+    ports:
+      - "6332:9500"
+    extra_hosts:
+      - "host.docker.internal:host-gateway" # Required for CI, works by default on macOS
+
+  # Used to programmatically create git repositories
+  git_api:
+    image: ghcr.io/codecrafters-io/git-api/web:v122
+    # comment out to build locally
+    # build:
+    #   context: ../git-api
+    environment:
+      GIT_ROOT_PATH: /usr/git
+      SENTRY_ENV: "local"
+    volumes:
+      - git_data:/usr/git
+    ports:
+      - "6333:5000"
+
+  logstream_redis:
+    image: redis:alpine
+    ports:
+      - "6334:6379"
+
+volumes:
+  git_data:
diff --git a/test-runner/go.mod b/test-runner/go.mod
new file mode 100644
index 0000000..b409f39
--- /dev/null
+++ b/test-runner/go.mod
@@ -0,0 +1,36 @@
+module github.com/codecrafters-io/test-runner
+
+go 1.23
+
+toolchain go1.24.2
+
+require (
+	github.com/codecrafters-io/logstream v0.2.3
+	github.com/egym-playground/go-prefix-writer v0.0.0-20180609083313-7326ea162eca
+	github.com/fatih/color v1.16.0
+	github.com/getsentry/sentry-go v0.28.0
+	github.com/google/uuid v1.6.0
+	github.com/hashicorp/go-retryablehttp v0.7.8
+	github.com/otiai10/copy v0.0.0-20240925044834-49b0b590f1e1
+	github.com/stretchr/testify v1.9.0
+	gopkg.in/yaml.v2 v2.4.0
+	gvisor.dev/gvisor v0.0.0-20231013233859-1a5aee553938
+)
+
+require (
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	github.com/go-redis/redis/v8 v8.11.5 // indirect
+	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
+	github.com/kr/text v0.2.0 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/otiai10/mint v1.6.3 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rohitpaulk/asyncwriter v0.0.2 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/test-runner/go.sum b/test-runner/go.sum
new file mode 100644
index 0000000..770639a
--- /dev/null
+++ b/test-runner/go.sum
@@ -0,0 +1,83 @@
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/codecrafters-io/logstream v0.2.3 h1:eHVmn3J2o7rTx9e73ikLsUbYOG0yZc/I1iXbs9jk5QI=
+github.com/codecrafters-io/logstream v0.2.3/go.mod h1:6iRBMIRZqSy7s4xKWJRnbDXvv7EDmlD/TtacC++h7q0=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
+github.com/egym-playground/go-prefix-writer v0.0.0-20180609083313-7326ea162eca h1:sWNMfkKG8GW1pGUyNlbsWq6f04pFgcsomY+Fly8XdB4=
+github.com/egym-playground/go-prefix-writer v0.0.0-20180609083313-7326ea162eca/go.mod h1:Ar+qogA+fkjeUR18xJfFzrMSjfs/sCPO+yjVvhXpyEg=
+github.com/fatih/color v1.16.0 h1:zmkK9Ngbjj+K0yRhTVONQh1p/HknKYSlNT+vZCzyokM=
+github.com/fatih/color v1.16.0/go.mod h1:fL2Sau1YI5c0pdGEVCbKQbLXB6edEj1ZgiY4NijnWvE=
+github.com/fsnotify/fsnotify v1.4.9 h1:hsms1Qyu0jgnwNXIxa+/V/PDsU6CfLf6CNO8H7IWoS4=
+github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
+github.com/getsentry/sentry-go v0.28.0 h1:7Rqx9M3ythTKy2J6uZLHmc8Sz9OGgIlseuO1iBX/s0M=
+github.com/getsentry/sentry-go v0.28.0/go.mod h1:1fQZ+7l7eeJ3wYi82q5Hg8GqAPgefRq+FP/QhafYVgg=
+github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=
+github.com/go-errors/errors v1.4.2/go.mod h1:sIVyrIiJhuEF+Pj9Ebtd6P/rEYROXFi3BopGUQ5a5Og=
+github.com/go-redis/redis/v8 v8.11.5 h1:AcZZR7igkdvfVmQTPnu9WE37LRrO/YrBH5zWyjDC0oI=
+github.com/go-redis/redis/v8 v8.11.5/go.mod h1:gREzHqY1hg6oD9ngVRbLStwAWKhA0FEgq8Jd4h5lpwo=
+github.com/go-redis/redismock/v8 v8.11.5 h1:RJFIiua58hrBrSpXhnGX3on79AU3S271H4ZhRI1wyVo=
+github.com/go-redis/redismock/v8 v8.11.5/go.mod h1:UaAU9dEe1C+eGr+FHV5prCWIt0hafyPWbGMEWE0UWdA=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hashicorp/go-cleanhttp v0.5.2 h1:035FKYIWjmULyFRBKPs8TBQoi0x6d9G4xc9neXJWAZQ=
+github.com/hashicorp/go-cleanhttp v0.5.2/go.mod h1:kO/YDlP8L1346E6Sodw+PrpBSV4/SoxCXGY6BqNFT48=
+github.com/hashicorp/go-hclog v1.6.3 h1:Qr2kF+eVWjTiYmU7Y31tYlP1h0q/X3Nl3tPGdaB11/k=
+github.com/hashicorp/go-hclog v1.6.3/go.mod h1:W4Qnvbt70Wk/zYJryRzDRU/4r0kIg0PVHBcfoyhpF5M=
+github.com/hashicorp/go-retryablehttp v0.7.8 h1:ylXZWnqa7Lhqpk0L1P1LzDtGcCR0rPVUrx/c8Unxc48=
+github.com/hashicorp/go-retryablehttp v0.7.8/go.mod h1:rjiScheydd+CxvumBsIrFKlx3iS0jrZ7LvzFGFmuKbw=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/nxadm/tail v1.4.11 h1:8feyoE3OzPrcshW5/MJ4sGESc5cqmGkGCWlco4l0bqY=
+github.com/nxadm/tail v1.4.11/go.mod h1:OTaG3NK980DZzxbRq6lEuzgU+mug70nY11sMd4JXXHc=
+github.com/onsi/ginkgo v1.16.5 h1:8xi0RTUf59SOSfEtZMvwTvXYMzG4gV23XVHOZiXNtnE=
+github.com/onsi/ginkgo v1.16.5/go.mod h1:+E8gABHa3K6zRBolWtd+ROzc/U5bkGt0FwiG042wbpU=
+github.com/onsi/gomega v1.18.1 h1:M1GfJqGRrBrrGGsbxzV5dqM2U2ApXefZCQpkukxYRLE=
+github.com/onsi/gomega v1.18.1/go.mod h1:0q+aL8jAiMXy9hbwj2mr5GziHiwhAIQpFmmtT5hitRs=
+github.com/otiai10/copy v0.0.0-20240925044834-49b0b590f1e1 h1:3gzBjrC8qp1EhwZV/x12sz5oUORNj9pqeZe1cU9kLYU=
+github.com/otiai10/copy v0.0.0-20240925044834-49b0b590f1e1/go.mod h1:oQwrEDDOci3IM8dJF0d8+jnbfPDllW6vUjNc3DoZm9I=
+github.com/otiai10/mint v1.6.3 h1:87qsV/aw1F5as1eH1zS/yqHY85ANKVMgkDrf9rcxbQs=
+github.com/otiai10/mint v1.6.3/go.mod h1:MJm72SBthJjz8qhefc4z1PYEieWmy8Bku7CjcAqyUSM=
+github.com/pingcap/errors v0.11.4 h1:lFuQV/oaUMGcD2tqt+01ROSmJs75VG1ToEOkZIZ4nE4=
+github.com/pingcap/errors v0.11.4/go.mod h1:Oi8TUi2kEtXXLMJk9l1cGmz20kV3TaQ0usTwv5KuLY8=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rohitpaulk/asyncwriter v0.0.2 h1:jaFb0vQIzauXkhC6rjhCatvjSd2Es6VW0CHF+GZCqbo=
+github.com/rohitpaulk/asyncwriter v0.0.2/go.mod h1:y3Ja8mupuzm26lOnNtZ2TpELfHsGVr1igRlSYd7Ob0E=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
+golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
+golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gvisor.dev/gvisor v0.0.0-20231013233859-1a5aee553938 h1:vRPyvNYWBKDUL+pqHMCuzDj6gipARDWpttH3pxrVILA=
+gvisor.dev/gvisor v0.0.0-20231013233859-1a5aee553938/go.mod h1:8hmigyCdYtw5xJGfQDJzSH5Ju8XEIDBnpyi8+O6GRt8=
diff --git a/test-runner/internal/backend/client.go b/test-runner/internal/backend/client.go
new file mode 100644
index 0000000..8461fdb
--- /dev/null
+++ b/test-runner/internal/backend/client.go
@@ -0,0 +1,63 @@
+package backend
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/codecrafters-io/test-runner/internal/globals"
+	"github.com/google/uuid"
+	"github.com/hashicorp/go-retryablehttp"
+)
+
+var globalClient = retryablehttp.NewClient()
+var loggingEnabled = true
+
+func init() {
+	globalClient.HTTPClient.Timeout = 10 * time.Second
+	globalClient.RetryWaitMin = 1 * time.Second
+	globalClient.RetryWaitMax = 5 * time.Second
+	globalClient.RetryMax = 5
+}
+
+func DisableLogging() {
+	loggingEnabled = false
+}
+
+func EnableLogging() {
+	loggingEnabled = true
+}
+
+func PerformRequest(method, path string, body []byte) (*http.Response, error) {
+	req := newRequest(method, path, body)
+
+	if loggingEnabled {
+		fmt.Printf("%s %s (request_id: \"%s\")\n", req.Method, req.URL.String(), req.Header.Get("X-Request-Id"))
+	}
+
+	retryableReq, err := retryablehttp.FromRequest(req)
+	if err != nil {
+		panic("CodeCrafters Internal Error: Failed to create retryable HTTP request: " + err.Error())
+	}
+
+	return globalClient.Do(retryableReq)
+}
+
+func newRequest(method, path string, body []byte) *http.Request {
+	if path[0] != '/' {
+		panic("path must start with a slash")
+	}
+
+	url := fmt.Sprintf("%s%s", globals.GetCodecraftersServerURL(), path)
+	req, err := http.NewRequest(method, url, bytes.NewBuffer(body))
+	if err != nil {
+		panic("CodeCrafters Internal Error: Failed to create HTTP request: " + err.Error())
+	}
+
+	req.Header.Add("Accept", "application/json")
+	req.Header.Add("Content-type", "application/json")
+	req.Header.Add("X-Request-Id", uuid.New().String())
+
+	return req
+}
diff --git a/test-runner/internal/backend/create_test_run_result.go b/test-runner/internal/backend/create_test_run_result.go
new file mode 100644
index 0000000..be51ce6
--- /dev/null
+++ b/test-runner/internal/backend/create_test_run_result.go
@@ -0,0 +1,41 @@
+package backend
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+func CreateTestRunResult(testRunId string, testRunnerId string, logs []byte, status string) error {
+	body := map[string]string{
+		"test_run_id":    testRunId,
+		"test_runner_id": testRunnerId,
+		"status":         status,
+		"logs_base64":    base64.StdEncoding.EncodeToString(logs),
+	}
+
+	bodyJson, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal JSON: %w", err)
+	}
+
+	resp, err := PerformRequest("POST", "/services/test_runner/create_test_run_result", bodyJson)
+	if err != nil {
+		return fmt.Errorf("HTTP request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	fmt.Printf("Response: %d\n", resp.StatusCode)
+
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
+	}
+
+	return nil
+}
diff --git a/test-runner/internal/backend/finalize_build.go b/test-runner/internal/backend/finalize_build.go
new file mode 100644
index 0000000..693b65e
--- /dev/null
+++ b/test-runner/internal/backend/finalize_build.go
@@ -0,0 +1,39 @@
+package backend
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+func FinalizeBuild(buildId string, status string, logs []byte) error {
+	body := map[string]string{
+		"test_runner_build_id": buildId,
+		"status":               status,
+		"logs_base64":          base64.StdEncoding.EncodeToString(logs),
+	}
+
+	bodyJson, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal JSON: %w", err)
+	}
+
+	resp, err := PerformRequest("POST", "/services/test_runner/finalize_test_runner_build", bodyJson)
+	if err != nil {
+		return fmt.Errorf("HTTP request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == 200 {
+		return nil
+	} else {
+
+		bodyBytes, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return fmt.Errorf("unexpected HTTP status %d. Body read error: %w", resp.StatusCode, err)
+		}
+
+		return fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
+	}
+}
diff --git a/test-runner/internal/backend/report_shutdown.go b/test-runner/internal/backend/report_shutdown.go
new file mode 100644
index 0000000..a4f8942
--- /dev/null
+++ b/test-runner/internal/backend/report_shutdown.go
@@ -0,0 +1,37 @@
+package backend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+func ReportShutdown(testRunnerId string) error {
+	body := map[string]string{
+		"test_runner_id": testRunnerId,
+	}
+
+	bodyJson, err := json.Marshal(body)
+	if err != nil {
+		return fmt.Errorf("failed to marshal JSON: %w", err)
+	}
+
+	resp, err := PerformRequest("POST", "/services/test_runner/report_shutdown", bodyJson)
+	if err != nil {
+		return fmt.Errorf("HTTP request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	fmt.Printf("Response: %d\n", resp.StatusCode)
+
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	if resp.StatusCode == 200 {
+		return nil
+	} else {
+		return fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
+	}
+}
diff --git a/test-runner/internal/backend/reserve_test_run.go b/test-runner/internal/backend/reserve_test_run.go
new file mode 100644
index 0000000..a87f75d
--- /dev/null
+++ b/test-runner/internal/backend/reserve_test_run.go
@@ -0,0 +1,62 @@
+package backend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+type HTTPStatusError struct {
+	StatusCode int
+}
+
+func (e *HTTPStatusError) Error() string {
+	return fmt.Sprintf("HTTP status %d", e.StatusCode)
+}
+
+type ReservedTestRun struct {
+	ID            string `json:"id"`
+	CommitSHA     string `json:"commit_sha"`
+	TestCasesJSON string `json:"test_cases_json"`
+	LogstreamURL  string `json:"logstream_url"`
+}
+
+type ReserveTestRunResponse struct {
+	TestRun     *ReservedTestRun `json:"test_run"`
+	ShouldRetry bool             `json:"should_retry"`
+}
+
+func ReserveTestRun(testRunnerId string) (ReserveTestRunResponse, error) {
+	path := fmt.Sprintf("/services/test_runner/reserve_test_run?test_runner_id=%s", testRunnerId)
+
+	resp, err := PerformRequest("POST", path, nil)
+	if err != nil {
+		return ReserveTestRunResponse{}, fmt.Errorf("HTTP request failed: %w", err)
+	}
+
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return ReserveTestRunResponse{}, fmt.Errorf("read response failed: %w", err)
+	}
+
+	fmt.Printf("Response (%d): %s\n", resp.StatusCode, string(body))
+
+	// Handle legacy response (TODO: Remove this once we've migrated all clients)
+	if resp.StatusCode == 202 {
+		return ReserveTestRunResponse{ShouldRetry: false}, nil
+	}
+
+	if resp.StatusCode == 200 {
+		var reserveTestRunResponse ReserveTestRunResponse
+
+		if err = json.Unmarshal(body, &reserveTestRunResponse); err != nil {
+			return ReserveTestRunResponse{}, fmt.Errorf("unable to parse response: %w", err)
+		}
+
+		return reserveTestRunResponse, nil
+	} else {
+		return ReserveTestRunResponse{}, &HTTPStatusError{StatusCode: resp.StatusCode}
+	}
+}
diff --git a/test-runner/internal/backend/trigger_infrastructure_rebuild.go b/test-runner/internal/backend/trigger_infrastructure_rebuild.go
new file mode 100644
index 0000000..54fdac9
--- /dev/null
+++ b/test-runner/internal/backend/trigger_infrastructure_rebuild.go
@@ -0,0 +1,49 @@
+package backend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+type TriggerInfrastructureRebuildResponse struct {
+	ID           string `json:"id"`
+	CommitSHA    string `json:"commit_sha"`
+	LogstreamURL string `json:"logstream_url"`
+}
+
+func TriggerInfrastructureRebuild(testRunId string, testRunnerId string) (TriggerInfrastructureRebuildResponse, error) {
+	body := map[string]string{
+		"test_run_id":    testRunId,
+		"test_runner_id": testRunnerId,
+	}
+
+	bodyJson, err := json.Marshal(body)
+	if err != nil {
+		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to marshal JSON: %w", err)
+	}
+
+	resp, err := PerformRequest("POST", "/services/test_runner/rebuild_for_test_run", bodyJson)
+	if err != nil {
+		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("HTTP request failed: %w", err)
+	}
+
+	defer resp.Body.Close()
+	bodyBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to read response body: %w", err)
+	}
+
+	if resp.StatusCode != 200 {
+		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
+	}
+
+	buildResponse := &TriggerInfrastructureRebuildResponse{}
+	err = json.Unmarshal(bodyBytes, buildResponse)
+
+	if err != nil {
+		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to parse response into submission: %w", err)
+	}
+
+	return *buildResponse, nil
+}
diff --git a/test-runner/internal/build_image.go b/test-runner/internal/build_image.go
new file mode 100644
index 0000000..49a9ae5
--- /dev/null
+++ b/test-runner/internal/build_image.go
@@ -0,0 +1,109 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/codecrafters-io/test-runner/internal/globals"
+	"github.com/egym-playground/go-prefix-writer/prefixer"
+	cp "github.com/otiai10/copy"
+	"gvisor.dev/gvisor/pkg/linewriter"
+)
+
+type RemoteDockerImageConfiguration struct {
+	ImageName        string
+	ImageTag         string
+	RegistryDomain   string
+	RegistryUsername string
+	RegistryPassword string
+	DepotToken       string
+	DepotProject     string
+}
+
+func (c RemoteDockerImageConfiguration) FullTag() string {
+	return fmt.Sprintf("%s/%s:%s", c.RegistryDomain, c.ImageName, c.ImageTag)
+}
+
+func BuildImage(build *TestRunnerBuild, dockerImageConfiguration RemoteDockerImageConfiguration, repositoryDir string, dockerfilePath string, testerDir string, testRunnerDir string, repositoryId string) (bool, error) {
+	newTesterDir := filepath.Join(repositoryDir, "tester")
+	newTestRunnerDir := filepath.Join(repositoryDir, "test-runner")
+
+	for _, dir := range []string{newTesterDir, newTestRunnerDir} {
+		if _, err := os.Stat(dir); !os.IsNotExist(err) {
+			removeErr := os.RemoveAll(dir)
+			if removeErr != nil {
+				return false, fmt.Errorf("failed to remove directory: %w", removeErr)
+			}
+		}
+	}
+
+	if err := cp.Copy(testerDir, newTesterDir); err != nil {
+		return false, fmt.Errorf("failed to copy tester directory: %w", err)
+	}
+
+	if err := cp.Copy(testRunnerDir, newTestRunnerDir); err != nil {
+		return false, fmt.Errorf("failed to copy test-runner directory: %w", err)
+	}
+
+	commandParts := []string{
+		"depot",
+		"build",
+		"--provenance", "false",
+		"--token", dockerImageConfiguration.DepotToken,
+		"--project", dockerImageConfiguration.DepotProject,
+		"--tag", dockerImageConfiguration.FullTag(),
+		"--file", dockerfilePath,
+		"--build-arg", fmt.Sprintf("REPOSITORY_ID=%s", repositoryId),
+		"--build-arg", fmt.Sprintf("CODECRAFTERS_SERVER_URL=%s", globals.GetCodecraftersServerURL()),
+		"--push",
+		repositoryDir,
+	}
+
+	cmd := exec.Command(commandParts[0], commandParts[1:]...)
+
+	userLogsSink := build
+	prefixedWriter := prefixer.New(userLogsSink, func() string { return "\033[33m[build]\033[0m " })
+	buildLogsProcessor := NewBuildLogsProcessor(prefixedWriter)
+	lineWriter := linewriter.NewWriter(func(p []byte) { buildLogsProcessor.OnLogLine(p) })
+
+	cmd.Stdout = lineWriter // Stdout isn't relevant for builds
+	cmd.Stderr = lineWriter // Let's send both raw and prefixed logs to stderr
+
+	prefixedWriter.Write([]byte(fmt.Sprintf("\033[34m%s\033[0m\n", "Starting build...")))
+	prefixedWriter.Write([]byte(fmt.Sprintf("\033[34m%s\033[0m\n", "If you don't see logs for 60s+, please contact us at hello@codecrafters.io")))
+
+	fmt.Printf("Running command: %s\n", cmd.String())
+
+	// TODO: More prefixedWriter logs?
+
+	err := cmd.Run() // Also prints logs, since we set cmd.Stdout and cmd.Stderr
+
+	if exitError, ok := err.(*exec.ExitError); ok {
+		prefixedWriter.Write([]byte("\033[31mBuild failed. Check the logs above for the reason.\033[0m\n"))
+		prefixedWriter.Write([]byte("\033[31mIf you think this is a CodeCrafters error, please contact us at hello@codecrafters.io.\033[0m\n"))
+		userLogsSink.Write([]byte("\n"))
+		return exitError.ExitCode() == 0, nil
+	}
+
+	if err != nil {
+		prefixedWriter.Write([]byte("\033[31mBuild failed. Check the logs above for the reason.\033[0m\n"))
+		prefixedWriter.Write([]byte("\033[31mIf you think this is a CodeCrafters error, please contact us at hello@codecrafters.io.\033[0m\n"))
+		userLogsSink.Write([]byte("\n"))
+		return false, nil // If the build command itself fails, for now we'll assume it was a user error.
+	}
+
+	prefixedWriter.Write([]byte("\033[32mBuild successful.\033[0m\n"))
+	userLogsSink.Write([]byte("\n"))
+
+	// Ensure we don't leave any unflushed logs
+	if build.testRunLogstreamWriter != nil {
+		if err := build.testRunLogstreamWriter.Flush(); err != nil {
+			// Don't report a user error for now
+			fmt.Printf("CodeCrafters Internal Error: failed to flush logs: %v\n", err)
+		}
+	}
+
+	return true, nil
+}
diff --git a/test-runner/internal/build_logs_processor.go b/test-runner/internal/build_logs_processor.go
new file mode 100644
index 0000000..4349951
--- /dev/null
+++ b/test-runner/internal/build_logs_processor.go
@@ -0,0 +1,57 @@
+package internal
+
+import (
+	"fmt"
+	"io"
+	"regexp"
+)
+
+type buildLogsProcessor struct {
+	// lastLine          []byte
+	currentBuildStepLine []byte
+	writer               io.Writer
+}
+
+var buildStepLineRegex = regexp.MustCompile(`^#(\d+) \[[^\]]+\] (.*)$`)
+var buildStepDoneRegex = regexp.MustCompile(`^#(\d+) DONE .*$`)
+var buildStepCachedRegex = regexp.MustCompile(`^#(\d+) CACHED.*$`)
+var buildProgressLineRegex = regexp.MustCompile(`^#(\d+) [\d.]+ (.*)$`)
+var buildErrorLineRegex = regexp.MustCompile(`^#(\d+) ERROR: (.*)$`)
+
+// func (p *buildLogsProcessor) currentBuildStepNumber() string {
+// 	return string(buildStepLineRegex.FindSubmatch(p.currentBuildStepLine)[1])
+// }
+
+func (p *buildLogsProcessor) OnLogLine(line []byte) {
+	// p.writer.Write(append([]byte("[Verbose Logger] "), line...))
+	if buildStepLineRegex.Match(line) {
+		// Ignore the line
+		p.currentBuildStepLine = line
+	} else if buildStepDoneRegex.Match(line) {
+		stepNumber := buildStepDoneRegex.FindSubmatch(line)[1]
+		p.writer.Write([]byte(fmt.Sprintf("Step %s complete.\n", stepNumber)))
+		p.currentBuildStepLine = nil
+	} else if buildStepCachedRegex.Match(line) {
+		stepNumber := buildStepCachedRegex.FindSubmatch(line)[1]
+		p.writer.Write([]byte(fmt.Sprintf("Step %s complete.\n", stepNumber)))
+		p.currentBuildStepLine = nil
+	} else if buildErrorLineRegex.Match(line) {
+		error := string(buildErrorLineRegex.FindSubmatch(line)[2])
+		p.writer.Write([]byte(fmt.Sprintf("Error: %s.\n", error)))
+	} else {
+		if p.currentBuildStepLine == nil {
+			// Ignore the line
+		} else {
+			if buildProgressLineRegex.Match(line) {
+				progressText := string(buildProgressLineRegex.FindSubmatch(line)[2])
+				p.writer.Write([]byte(fmt.Sprintf("> %s\n", progressText)))
+			}
+		}
+	}
+}
+
+func NewBuildLogsProcessor(writer io.Writer) *buildLogsProcessor {
+	return &buildLogsProcessor{
+		writer: writer,
+	}
+}
diff --git a/test-runner/internal/build_logs_processor_test.go b/test-runner/internal/build_logs_processor_test.go
new file mode 100644
index 0000000..31fe67b
--- /dev/null
+++ b/test-runner/internal/build_logs_processor_test.go
@@ -0,0 +1,68 @@
+package internal
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBuildLogsProcessorSimple(t *testing.T) {
+	bytesBuffer := bytes.NewBuffer([]byte{})
+	p := NewBuildLogsProcessor(bytesBuffer)
+
+	p.OnLogLine([]byte("#1 [depot] build: xxx"))
+	p.OnLogLine([]byte("#1 DONE 0.0s"))
+	p.OnLogLine([]byte(""))
+	p.OnLogLine([]byte("#2 [depot] launching amd64 machine"))
+	p.OnLogLine([]byte("#2 DONE 0.3s"))
+
+	assert.Equal(t, "Step 1 complete.\nStep 2 complete.\n", bytesBuffer.String())
+}
+
+func TestBuildLogsProcessorCached(t *testing.T) {
+	bytesBuffer := bytes.NewBuffer([]byte{})
+	p := NewBuildLogsProcessor(bytesBuffer)
+
+	logs := `
+#26 [19/21] WORKDIR /app
+#26 CACHED
+
+#27 [20/21] COPY . /app
+#27 DONE 0.2s
+`
+
+	logLines := bytes.Split([]byte(logs), []byte("\n"))
+
+	for _, line := range logLines {
+		p.OnLogLine(line)
+	}
+
+	assert.Equal(t, "Step 26 complete.\nStep 27 complete.\n", bytesBuffer.String())
+}
+
+func TestBuildLogsProcessorRunCommandProgress(t *testing.T) {
+	bytesBuffer := bytes.NewBuffer([]byte{})
+	p := NewBuildLogsProcessor(bytesBuffer)
+
+	logs := `
+#13 [ 6/21] WORKDIR /app
+#13 DONE 0.0s
+
+#14 [ 7/21] RUN cargo build --release --target-dir=/tmp/codecrafters-redis-target
+#14 0.600 Updating crates.io index
+#14 0.678 Downloading crates...
+#14 DONE 8.3s
+
+#15 [ 8/21] RUN rm /tmp/codecrafters-redis-target/release/redis-starter-rust
+#15 DONE 0.2s
+`
+
+	logLines := bytes.Split([]byte(logs), []byte("\n"))
+
+	for _, line := range logLines {
+		p.OnLogLine(line)
+	}
+
+	assert.Equal(t, "Step 13 complete.\n> Updating crates.io index\n> Downloading crates...\nStep 14 complete.\nStep 15 complete.\n", bytesBuffer.String())
+}
diff --git a/test-runner/internal/color/color.go b/test-runner/internal/color/color.go
new file mode 100644
index 0000000..f9d4bac
--- /dev/null
+++ b/test-runner/internal/color/color.go
@@ -0,0 +1,23 @@
+package color
+
+import fatihColor "github.com/fatih/color"
+
+// Red colors the given text in red
+func Red(text string) string {
+	colorer := fatihColor.New(fatihColor.FgRed)
+	colorer.EnableColor()
+	return colorer.SprintFunc()(text)
+}
+
+// Blue colors the given text in blue
+func Blue(text string) string {
+	colorer := fatihColor.New(fatihColor.FgBlue)
+	colorer.EnableColor()
+	return colorer.SprintFunc()(text)
+}
+
+func Green(text string) string {
+	colorer := fatihColor.New(fatihColor.FgGreen)
+	colorer.EnableColor()
+	return colorer.SprintFunc()(text)
+}
diff --git a/test-runner/internal/commands/build_image_command.go b/test-runner/internal/commands/build_image_command.go
new file mode 100644
index 0000000..702848d
--- /dev/null
+++ b/test-runner/internal/commands/build_image_command.go
@@ -0,0 +1,260 @@
+package commands
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/codecrafters-io/test-runner/internal"
+	"github.com/codecrafters-io/test-runner/internal/backend"
+	"github.com/codecrafters-io/test-runner/internal/color"
+	"github.com/codecrafters-io/test-runner/internal/globals"
+)
+
+// If err is FriendlyError, it's a user error. Otherwise, it's an internal error.
+// TODO: Handle write errors if InitLogging actually failed?
+func handleErrorDuringBuild(build *internal.TestRunnerBuild, logPrefix string, err error) int {
+	if logPrefix != "" {
+		fmt.Printf("%s: %s\n", logPrefix, err)
+	} else {
+		fmt.Printf("%s\n", err)
+	}
+
+	if build != nil {
+		if friendlyErr, ok := err.(*internal.FriendlyError); ok {
+			if !friendlyErr.IsLogged {
+				lines := strings.Split(friendlyErr.UserError, "\n")
+				for _, line := range lines {
+					build.Write([]byte(fmt.Sprintf("%s\n", color.Red(line))))
+				}
+			}
+
+			build.Write([]byte(fmt.Sprintf("%s\n", color.Red("If you think this is a CodeCrafters bug, please contact us at hello@codecrafters.io."))))
+
+			if err = flushLogsAndFinalizeBuild(build, "failure"); err != nil {
+				fmt.Printf("Failed to create build result: %s\n", err)
+				return 1 // Failed to report
+			} else {
+				return 0 // User error
+			}
+		} else {
+			build.Write([]byte(fmt.Sprintf("%s\n", color.Red(fmt.Sprintf("CodeCrafters internal error: %s", err)))))
+			build.Write([]byte(fmt.Sprintf("%s\n", color.Red("Try again? Contact us at hello@codecrafters.io if this persists."))))
+
+			// Best effort, we're still going to return 1 since the error is an internal error
+			if err = flushLogsAndFinalizeBuild(build, "error"); err != nil {
+				fmt.Printf("Failed to create build result: %s\n", err)
+			}
+
+			return 1
+		}
+	}
+	return 1
+}
+
+func flushLogsAndFinalizeBuild(build *internal.TestRunnerBuild, status string) error {
+	if status != "success" && status != "failure" && status != "error" {
+		panic(fmt.Errorf("invalid status: %s", status))
+	}
+
+	logs, err := build.ReadLogsFromFile()
+	if err != nil {
+		return err
+	}
+
+	build.Close() // Ensure we close the logstream writer
+	build.CleanupLogging()
+
+	return backend.FinalizeBuild(build.ID, status, logs)
+}
+
+func BuildImageCommand() int {
+	var buildCommitSha string
+	var buildId string
+	var buildLogstreamUrl string
+	var buildTestRunLogstreamUrl string
+	var buildpackDockerfilePath string
+	var buildpackSlug string
+	var codecraftersServerUrl string
+	var courseSlug string
+	var depotToken string
+	var depotProject string
+	var dockerImageName string
+	var dockerImageTag string
+	var dockerRegistryDomain string
+	var dockerRegistryPassword string
+	var dockerRegistryUsername string
+	var repositoryDir string
+	var repositoryId string
+	var testRunnerDir string
+	var testerDir string
+
+	flag.StringVar(&buildCommitSha, "build-commit-sha", "", "The SHA of the commit to use for building")
+	flag.StringVar(&buildId, "build-id", "", "The ID of the build")
+	flag.StringVar(&buildLogstreamUrl, "build-logstream-url", "", "The Logstream URL of the build")
+	flag.StringVar(&buildTestRunLogstreamUrl, "build-test-run-logstream-url", "", "The Logstream URL of a test run that's waiting on this build")
+	flag.StringVar(&buildpackDockerfilePath, "buildpack-dockerfile-path", "", "The path to the buildpack Dockerfile")
+	flag.StringVar(&buildpackSlug, "buildpack-slug", "", "The slug of the buildpack")
+	flag.StringVar(&codecraftersServerUrl, "codecrafters-server-url", "", "The server URL of Codecrafters")
+	flag.StringVar(&courseSlug, "course-slug", "", "The slug of the course")
+	flag.StringVar(&depotToken, "depot-token", "", "The Depot token to use")
+	flag.StringVar(&depotProject, "depot-project", "", "The Depot project to use")
+	flag.StringVar(&dockerImageName, "docker-image-name", "", "The name of the Docker image")
+	flag.StringVar(&dockerImageTag, "docker-image-tag", "", "The tag of the Docker image")
+	flag.StringVar(&dockerRegistryDomain, "docker-registry-domain", "", "The domain of the Docker registry")
+	flag.StringVar(&dockerRegistryPassword, "docker-registry-password", "", "The password of the Docker registry")
+	flag.StringVar(&dockerRegistryUsername, "docker-registry-username", "", "The username of the Docker registry")
+	flag.StringVar(&repositoryId, "repository-id", "", "The ID of the repository")
+	flag.StringVar(&repositoryDir, "repository-dir", "", "The directory of the repository")
+	flag.StringVar(&testRunnerDir, "test-runner-dir", "", "The directory of the test runner")
+	flag.StringVar(&testerDir, "tester-dir", "", "The directory of the tester")
+
+	flag.CommandLine.Parse(os.Args[2:]) // Use 2: to avoid the first command
+
+	if codecraftersServerUrl == "" {
+		fmt.Println("codecrafters-server-url must be provided")
+		os.Exit(1)
+	}
+
+	globals.SetCodecraftersServerURL(codecraftersServerUrl)
+
+	fmt.Printf("buildId: %q, buildLogstreamUrl: %q\n", buildId, buildLogstreamUrl)
+
+	build := &internal.TestRunnerBuild{
+		CommitSHA:           buildCommitSha,
+		ID:                  buildId,
+		LogstreamURL:        buildLogstreamUrl,
+		TestRunLogstreamURL: buildTestRunLogstreamUrl,
+	}
+
+	if err := build.InitLogging(); err != nil {
+		return handleErrorDuringBuild(build, "Failed to initialize logging", err)
+	}
+	defer build.CleanupLogging()
+
+	// Just making sure we don't use these again, and use values on build instead.
+	buildId = ""
+	buildLogstreamUrl = ""
+	buildCommitSha = ""
+	buildTestRunLogstreamUrl = ""
+
+	flags := map[string]string{
+		"buildpack-dockerfile-path": buildpackDockerfilePath,
+		"buildpack-slug":            buildpackSlug,
+		"course-slug":               courseSlug,
+		"depot-token":               depotToken,
+		"depot-project":             depotProject,
+		"repository-id":             repositoryId,
+		"repository-dir":            repositoryDir,
+		"tester-dir":                testerDir,
+		"test-runner-dir":           testRunnerDir,
+		"docker-image-name":         dockerImageName,
+		"docker-image-tag":          dockerImageTag,
+		"docker-registry-domain":    dockerRegistryDomain,
+		"docker-registry-username":  dockerRegistryUsername,
+		"docker-registry-password":  dockerRegistryPassword,
+	}
+
+	for flagName, flagValue := range flags {
+		fmt.Printf("%-30s: %q\n", flagName, flagValue)
+		if flagValue == "" {
+			return handleErrorDuringBuild(build, "", fmt.Errorf("%s must be provided", flagName))
+		}
+	}
+
+	if _, err := os.Stat(testerDir); os.IsNotExist(err) {
+		return handleErrorDuringBuild(build, "", fmt.Errorf("tester dir (%s) does not exist", testerDir))
+	}
+
+	if _, err := os.Stat(testRunnerDir); os.IsNotExist(err) {
+		return handleErrorDuringBuild(build, "", fmt.Errorf("test runner dir (%s) does not exist", testRunnerDir))
+	}
+
+	if _, err := os.Stat(repositoryDir); os.IsNotExist(err) {
+		return handleErrorDuringBuild(build, "", fmt.Errorf("repository dir (%s) does not exist", repositoryDir))
+	}
+
+	currentCommitSha, err := internal.GetHeadCommitSha(repositoryDir)
+	if err != nil {
+		return handleErrorDuringBuild(build, "Failed to get HEAD commit SHA", err)
+	}
+
+	if build.CommitSHA == "" {
+		build.CommitSHA = currentCommitSha
+	}
+
+	if build.CommitSHA != currentCommitSha {
+		fmt.Printf("Checking out commit %s\n", build.CommitSHA)
+		if err := internal.SwitchToCommit(repositoryDir, build.CommitSHA); err != nil {
+			return handleErrorDuringBuild(build, fmt.Sprintf("failed to checkout commit %s", build.CommitSHA), err)
+		}
+	} else {
+		fmt.Println("HEAD commit SHA is same as expected")
+	}
+
+	buildpackSlugInRepo, friendlyErr := internal.GetBuildpack(repositoryDir)
+	if friendlyErr != nil {
+		return handleErrorDuringBuild(build, "Failed to get buildpack", friendlyErr)
+	}
+
+	if buildpackSlugInRepo != buildpackSlug {
+		return handleErrorDuringBuild(build, "", &internal.FriendlyError{
+			UserError: fmt.Sprintf("Detected changes to buildpack (old: %s, new: %s).\nThis isn't supported. If you're trying to upgrade to a new language version, please run `codecrafters update-buildpack`.", buildpackSlug, buildpackSlugInRepo),
+		})
+	}
+
+	fmt.Printf("Buildpack Slug: %s\n", buildpackSlugInRepo)
+	fmt.Printf("Buildpack Dockerfile: %s\n", buildpackDockerfilePath)
+
+	if _, err := os.Stat(buildpackDockerfilePath); os.IsNotExist(err) {
+		return handleErrorDuringBuild(build, "", fmt.Errorf("dockerfile (%s) does not exist", buildpackDockerfilePath))
+	}
+
+	dockerignorePath := filepath.Join(repositoryDir, ".dockerignore")
+	if _, err := os.Stat(dockerignorePath); err == nil {
+		if err := os.RemoveAll(dockerignorePath); err != nil {
+			return handleErrorDuringBuild(build, "Failed to remove .dockerignore", err)
+		}
+	}
+
+	buildWasSuccessful, err := internal.BuildImage(
+		build,
+		internal.RemoteDockerImageConfiguration{
+			ImageName:        dockerImageName,
+			ImageTag:         dockerImageTag,
+			RegistryDomain:   dockerRegistryDomain,
+			RegistryUsername: dockerRegistryUsername,
+			RegistryPassword: dockerRegistryPassword,
+			DepotToken:       depotToken,
+			DepotProject:     depotProject,
+		},
+		repositoryDir,
+		buildpackDockerfilePath,
+		testerDir,
+		testRunnerDir,
+		repositoryId,
+	)
+	if err != nil {
+		return handleErrorDuringBuild(build, "Failed to run tester", err)
+	}
+
+	if buildWasSuccessful {
+		fmt.Println("Build was successful")
+
+		err = flushLogsAndFinalizeBuild(build, "success")
+		if err != nil {
+			return handleErrorDuringBuild(build, "Failed to finalize build", err)
+		}
+	} else {
+		fmt.Println("Build was not successful")
+
+		err = flushLogsAndFinalizeBuild(build, "failure")
+		if err != nil {
+			return handleErrorDuringBuild(build, "Failed to finalize build", err)
+		}
+	}
+
+	return 0
+}
diff --git a/test-runner/internal/friendly_error.go b/test-runner/internal/friendly_error.go
new file mode 100644
index 0000000..6e81601
--- /dev/null
+++ b/test-runner/internal/friendly_error.go
@@ -0,0 +1,11 @@
+package internal
+
+type FriendlyError struct {
+	UserError     string
+	InternalError string
+	IsLogged      bool // Helps us avoid logging the same error twice
+}
+
+func (e *FriendlyError) Error() string {
+	return e.UserError
+}
diff --git a/test-runner/internal/get_buildpack.go b/test-runner/internal/get_buildpack.go
new file mode 100644
index 0000000..93ae0d2
--- /dev/null
+++ b/test-runner/internal/get_buildpack.go
@@ -0,0 +1,42 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v2"
+)
+
+func GetBuildpack(repositoryDir string) (string, error) {
+	file, err := os.Open(fmt.Sprintf("%s/codecrafters.yml", repositoryDir))
+	if err != nil {
+		return "", &FriendlyError{
+			UserError:     "Didn't find a codecrafters.yml file in your repository. This is required to run tests.",
+			InternalError: fmt.Sprintf("failed to open codecrafters.yml. err=%s", err),
+		}
+	}
+	defer file.Close()
+
+	decoder := yaml.NewDecoder(file)
+	var data map[string]interface{}
+	err = decoder.Decode(&data)
+	if err != nil {
+		return "", &FriendlyError{
+			UserError:     "Your codecrafters.yml file is not valid YAML. Please fix it and try again.",
+			InternalError: fmt.Sprintf("failed to decode codecrafters.yml. err=%s", err),
+		}
+	}
+
+	// Try buildpack first (new), then fall back to language_pack (old) for backwards compatibility
+	if buildpack, ok := data["buildpack"].(string); ok {
+		return strings.TrimSpace(buildpack), nil
+	} else if languagePack, ok := data["language_pack"].(string); ok {
+		return strings.TrimSpace(languagePack), nil
+	} else {
+		return "", &FriendlyError{
+			UserError:     "Could not find buildpack in codecrafters.yml. Please make sure codecrafters.yml is a valid YAML file with a buildpack key.",
+			InternalError: "codecrafters.yml is missing buildpack field",
+		}
+	}
+}
diff --git a/test-runner/internal/get_head_commit_sha.go b/test-runner/internal/get_head_commit_sha.go
new file mode 100644
index 0000000..7b5ac6e
--- /dev/null
+++ b/test-runner/internal/get_head_commit_sha.go
@@ -0,0 +1,18 @@
+package internal
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+func GetHeadCommitSha(repositoryDir string) (string, error) {
+	cmd := exec.Command("git", "-C", repositoryDir, "rev-parse", "HEAD")
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return "", fmt.Errorf("failed to get HEAD commit SHA: %w. Output: %v", err, string(output))
+	}
+
+	return strings.TrimSpace(string(output)), nil
+}
diff --git a/test-runner/internal/globals/codecrafters_server_url.go b/test-runner/internal/globals/codecrafters_server_url.go
new file mode 100644
index 0000000..954a227
--- /dev/null
+++ b/test-runner/internal/globals/codecrafters_server_url.go
@@ -0,0 +1,15 @@
+package globals
+
+var codecraftersServerURL string
+
+func SetCodecraftersServerURL(url string) {
+	codecraftersServerURL = url
+}
+
+func GetCodecraftersServerURL() string {
+	if codecraftersServerURL == "" {
+		panic("CodecraftersServerURL is not set")
+	}
+
+	return codecraftersServerURL
+}
diff --git a/test-runner/internal/move_app_cached_files_if_needed.go b/test-runner/internal/move_app_cached_files_if_needed.go
new file mode 100644
index 0000000..32c85e1
--- /dev/null
+++ b/test-runner/internal/move_app_cached_files_if_needed.go
@@ -0,0 +1,24 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+
+	cp "github.com/otiai10/copy"
+)
+
+func MoveAppCachedFilesIfNeeded(repositoryDir string) error {
+	if _, err := os.Stat("/app-cached"); !os.IsNotExist(err) {
+		fmt.Printf("Moving /app-cached to %s\n", repositoryDir)
+
+		err := cp.Copy("/app-cached", repositoryDir, cp.Options{
+			PreserveTimes: true, // Some caching strategies rely on file timestamps
+			PreserveOwner: true, // Some caching strategies rely on file ownership
+		})
+		if err != nil {
+			return fmt.Errorf("failed to copy dir: %s", err)
+		}
+	}
+
+	return nil
+}
diff --git a/test-runner/internal/run_precompilation_if_needed.go b/test-runner/internal/run_precompilation_if_needed.go
new file mode 100644
index 0000000..17921bd
--- /dev/null
+++ b/test-runner/internal/run_precompilation_if_needed.go
@@ -0,0 +1,71 @@
+package internal
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path"
+
+	"github.com/egym-playground/go-prefix-writer/prefixer"
+)
+
+func RunPrecompilationIfNeeded(testRun *TestRun, repositoryDir string) error {
+	logWriter := testRun
+	logWithPrefixWriter := prefixer.New(logWriter, func() string { return "\033[33m[compile]\033[0m " })
+
+	newPrecompileFilePath := path.Join(repositoryDir, ".codecrafters/compile.sh")
+	legacyPrecompileFilePath := "/codecrafters-precompile.sh"
+
+	var precompileFilePath string
+	_, newPrecompileFilePathErr := os.Stat(newPrecompileFilePath)
+	_, legacyPrecompileFilePathErr := os.Stat(legacyPrecompileFilePath)
+
+	if newPrecompileFilePathErr == nil {
+		precompileFilePath = newPrecompileFilePath
+	} else if legacyPrecompileFilePathErr == nil {
+		precompileFilePath = legacyPrecompileFilePath
+	} else if !errors.Is(newPrecompileFilePathErr, os.ErrNotExist) { // new script exists but failed to stat
+		return &FriendlyError{
+			UserError:     "CodeCrafters internal error: failed to stat precompile script: " + newPrecompileFilePathErr.Error(),
+			InternalError: "failed to stat precompile script: " + newPrecompileFilePathErr.Error(),
+		}
+	} else if !errors.Is(legacyPrecompileFilePathErr, os.ErrNotExist) { // legacy script exists but failed to stat
+		return &FriendlyError{
+			UserError:     "CodeCrafters internal error: failed to stat precompile script: " + legacyPrecompileFilePathErr.Error(),
+			InternalError: "failed to stat precompile script: " + legacyPrecompileFilePathErr.Error(),
+		}
+	}
+
+	// No precompile script found
+	if precompileFilePath == "" {
+		return nil
+	}
+
+	cmd := exec.Command("sh", precompileFilePath)
+	cmd.Env = os.Environ()
+	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_SUBMISSION_DIR=%s", repositoryDir)) // TODO: Legacy, remove
+	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_REPOSITORY_DIR=%s", repositoryDir))
+	cmd.Stdout = logWithPrefixWriter
+	cmd.Stderr = logWithPrefixWriter
+
+	err := cmd.Run()
+	if _, ok := err.(*exec.ExitError); ok {
+		logWithPrefixWriter.Write([]byte("\033[31mLooks like your code failed to compile.\033[0m\n"))
+		logWithPrefixWriter.Write([]byte("\033[31mIf you think this is a CodeCrafters error, please let us know at hello@codecrafters.io.\033[0m\n"))
+		logWriter.Write([]byte("\n"))
+
+		return &FriendlyError{
+			UserError:     "Compilation failed (user error!)",
+			InternalError: "Compilation failed (internal error!)",
+			IsLogged:      true,
+		}
+	} else if err != nil {
+		return &FriendlyError{
+			UserError:     "CodeCrafters internal error: failed to run precompile script: " + err.Error(),
+			InternalError: "failed to run precompile script: " + err.Error(),
+		}
+	}
+
+	return nil
+}
diff --git a/test-runner/internal/run_tester.go b/test-runner/internal/run_tester.go
new file mode 100644
index 0000000..bbedf76
--- /dev/null
+++ b/test-runner/internal/run_tester.go
@@ -0,0 +1,33 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path"
+)
+
+func RunTester(testRun *TestRun, repositoryDir string, testerDir string) (bool, error) {
+	cmd := exec.Command(path.Join(testerDir, "test.sh"))
+	cmd.Env = os.Environ()
+	cmd.Env = append(cmd.Env, "PYTHONUNBUFFERED=true")                                      // TODO: Move this to dockerfile?
+	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_SUBMISSION_DIR=%s", repositoryDir)) // TODO: Legacy, remove
+	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_REPOSITORY_DIR=%s", repositoryDir))
+	cmd.Env = append(cmd.Env, fmt.Sprintf("TESTER_DIR=%s", testerDir))
+	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_TEST_CASES_JSON=%s", testRun.TestCasesJSON))
+	cmd.Stdout = testRun
+	cmd.Stderr = testRun
+
+	err := cmd.Run()
+	if exitError, ok := err.(*exec.ExitError); ok {
+		if exitError.ExitCode() != 0 && exitError.ExitCode() != 1 {
+			return false, err
+		}
+
+		return exitError.ExitCode() == 0, nil
+	} else if err != nil {
+		return false, err
+	}
+
+	return true, nil
+}
diff --git a/test-runner/internal/switch_to_commit.go b/test-runner/internal/switch_to_commit.go
new file mode 100644
index 0000000..bbd53df
--- /dev/null
+++ b/test-runner/internal/switch_to_commit.go
@@ -0,0 +1,61 @@
+package internal
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"time"
+)
+
+func SwitchToCommit(repositoryDir string, newCommitSHA string) error {
+	commands := []struct {
+		name    string
+		args    []string
+		errMsg  string
+		timeout time.Duration
+	}{
+		// Clean up any untracked files, (such as dummy ones created in the Dockerfile)
+		{
+			name:    "git",
+			args:    []string{"-C", repositoryDir, "clean", "-fd"},
+			errMsg:  "failed to clean repository",
+			timeout: 2 * time.Second,
+		},
+		{
+			name:    "git",
+			args:    []string{"-C", repositoryDir, "fetch", "origin", newCommitSHA}, // This commit might not be on the default branch, so we need to fetch it specifically
+			errMsg:  "failed to fetch commit from origin",
+			timeout: 10 * time.Second,
+		},
+		{
+			name:    "git",
+			args:    []string{"-C", repositoryDir, "checkout", "-f", newCommitSHA},
+			errMsg:  "failed to checkout commit",
+			timeout: 10 * time.Second,
+		},
+	}
+
+	for _, command := range commands {
+		// Create a context with timeout
+		ctx, cancel := context.WithTimeout(context.Background(), command.timeout)
+		defer cancel()
+
+		// Start command with context
+		cmd := exec.CommandContext(ctx, command.name, command.args...)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+
+		err := cmd.Run()
+		if err != nil {
+			// Check if the error is due to timeout
+			if ctx.Err() == context.DeadlineExceeded {
+				return fmt.Errorf("%s, timeout after %d seconds", command.errMsg, int(command.timeout.Seconds()))
+			}
+
+			return fmt.Errorf("%s, %w", command.errMsg, err)
+		}
+	}
+
+	return nil
+}
diff --git a/test-runner/internal/test_run.go b/test-runner/internal/test_run.go
new file mode 100644
index 0000000..ad460be
--- /dev/null
+++ b/test-runner/internal/test_run.go
@@ -0,0 +1,78 @@
+package internal
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/codecrafters-io/logstream/redis"
+)
+
+type TestRun struct {
+	ID            string
+	CommitSHA     string
+	TestCasesJSON string
+	LogstreamURL  string
+
+	logstreamWriter *redis.Producer
+	logsFile        *os.File
+}
+
+func (t *TestRun) InitLogging() error {
+	logstreamWriter, err := redis.NewProducer(t.LogstreamURL)
+	if err != nil {
+		return fmt.Errorf("failed to create logstream writer: %w", err)
+	}
+
+	logsFile, err := os.CreateTemp("", "test-run")
+	if err != nil {
+		return fmt.Errorf("failed to create temporary file: %w", err)
+	}
+
+	t.logstreamWriter = logstreamWriter
+	t.logsFile = logsFile
+
+	return nil
+}
+
+func (t *TestRun) CleanupLogging() {
+	if t.logsFile != nil {
+		err := os.Remove(t.logsFile.Name())
+		if err != nil {
+			fmt.Printf("CodeCrafters Internal Error: unable to delete logs file: %v\n", err)
+		}
+
+		t.logsFile = nil
+	}
+}
+
+func (t *TestRun) ReadLogsFromFile() ([]byte, error) {
+	t.logsFile.Seek(0, 0)
+	logs, err := io.ReadAll(t.logsFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read logs from file: %w", err)
+	}
+
+	return logs, nil
+}
+
+func (t *TestRun) Write(p []byte) (n int, err error) {
+	_, logStreamError := t.logstreamWriter.Write(p)
+	_, fileError := t.logsFile.Write(p)
+	_, _ = os.Stdout.Write(p)
+
+	if logStreamError != nil {
+		return 0, fmt.Errorf("failed to write to logstream: %w", logStreamError)
+	}
+
+	if fileError != nil {
+		return 0, fmt.Errorf("failed to write to file: %w", fileError)
+	}
+
+	return len(p), nil
+}
+
+func (t *TestRun) Close() {
+	t.logstreamWriter.Close()
+	t.logsFile.Close()
+}
diff --git a/test-runner/internal/test_runner_build.go b/test-runner/internal/test_runner_build.go
new file mode 100644
index 0000000..06ed57d
--- /dev/null
+++ b/test-runner/internal/test_runner_build.go
@@ -0,0 +1,98 @@
+package internal
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/codecrafters-io/logstream/redis"
+)
+
+type TestRunnerBuild struct {
+	ID                  string
+	CommitSHA           string
+	LogstreamURL        string
+	TestRunLogstreamURL string // Logstream URL for a test run that's waiting on this build.
+
+	logstreamWriter        *redis.Producer
+	logsFile               *os.File
+	testRunLogstreamWriter *redis.Producer
+}
+
+func (b *TestRunnerBuild) InitLogging() error {
+	logstreamWriter, err := redis.NewProducer(b.LogstreamURL)
+	if err != nil {
+		return fmt.Errorf("failed to create logstream writer: %w", err)
+	}
+
+	b.logstreamWriter = logstreamWriter
+
+	logsFile, err := os.CreateTemp("", "test-runner-build")
+	if err != nil {
+		return fmt.Errorf("failed to create temporary file: %w", err)
+	}
+
+	b.logsFile = logsFile
+
+	if b.TestRunLogstreamURL != "" {
+		testRunLogstreamWriter, err := redis.NewProducer(b.TestRunLogstreamURL)
+		if err != nil {
+			return fmt.Errorf("failed to create test run logstream writer: %w", err)
+		}
+
+		b.testRunLogstreamWriter = testRunLogstreamWriter
+	}
+
+	return nil
+}
+
+func (b *TestRunnerBuild) CleanupLogging() {
+	if b.logsFile != nil {
+		err := os.Remove(b.logsFile.Name())
+		if err != nil {
+			fmt.Printf("CodeCrafters Internal Error: unable to delete logs file: %v\n", err)
+		}
+
+		b.logsFile = nil
+	}
+}
+
+func (b *TestRunnerBuild) ReadLogsFromFile() ([]byte, error) {
+	b.logsFile.Seek(0, 0)
+	logs, err := io.ReadAll(b.logsFile)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read logs from file: %w", err)
+	}
+
+	return logs, nil
+}
+
+func (b *TestRunnerBuild) Write(p []byte) (n int, err error) {
+	_, logStreamError := b.logstreamWriter.Write(p)
+	_, fileError := b.logsFile.Write(p)
+	os.Stdout.Write(p)
+
+	if logStreamError != nil {
+		return 0, fmt.Errorf("failed to write to logstream: %w", logStreamError)
+	}
+
+	if fileError != nil {
+		return 0, fmt.Errorf("failed to write to file: %w", fileError)
+	}
+
+	if b.testRunLogstreamWriter != nil {
+		_, testRunLogStreamError := b.testRunLogstreamWriter.Write(p)
+
+		if testRunLogStreamError != nil {
+			return 0, fmt.Errorf("failed to write to test run logstream: %w", testRunLogStreamError)
+		}
+	}
+
+	return len(p), nil
+}
+
+// We intentionally don't close b.testRunLogstreamWriter here because that'll need to receive test run logs later.
+func (b *TestRunnerBuild) Close() {
+	b.logstreamWriter.Close()
+	b.logsFile.Close()
+}
diff --git a/test-runner/internal/utils/sentry.go b/test-runner/internal/utils/sentry.go
new file mode 100644
index 0000000..88b8e3e
--- /dev/null
+++ b/test-runner/internal/utils/sentry.go
@@ -0,0 +1,28 @@
+package utils
+
+import (
+	"os"
+	"time"
+
+	"github.com/getsentry/sentry-go"
+)
+
+var defaultSentryDSN = "https://cf3aff40fb414dcc9311747852872623@o294739.ingest.us.sentry.io/5859980"
+
+func InitSentry() {
+	dsn, ok := os.LookupEnv("SENTRY_DSN")
+	if !ok {
+		dsn = defaultSentryDSN
+	}
+
+	err := sentry.Init(sentry.ClientOptions{
+		Dsn:              dsn,
+		Debug:            os.Getenv("SENTRY_DEBUG") == "1",
+		TracesSampleRate: 1.0,
+	})
+	_ = err // ignore
+}
+
+func TeardownSentry() {
+	sentry.Flush(time.Second)
+}
diff --git a/test-runner/main.go b/test-runner/main.go
new file mode 100644
index 0000000..bb02e66
--- /dev/null
+++ b/test-runner/main.go
@@ -0,0 +1,23 @@
+package main
+
+import (
+	"os"
+
+	"github.com/codecrafters-io/test-runner/internal/commands"
+	"github.com/codecrafters-io/test-runner/internal/utils"
+	"github.com/getsentry/sentry-go"
+)
+
+func main() {
+	utils.InitSentry()
+	defer utils.TeardownSentry()
+
+	exitCode := 0
+
+	func() {
+		defer sentry.Recover() // Ensure panics are captured and sent to Sentry
+		exitCode = commands.BuildImageCommand()
+	}()
+
+	os.Exit(exitCode)
+}
diff --git a/test-runner/main.goreleaser.yml b/test-runner/main.goreleaser.yml
new file mode 100644
index 0000000..6f26c50
--- /dev/null
+++ b/test-runner/main.goreleaser.yml
@@ -0,0 +1,11 @@
+builds:
+  - main: ./
+    binary: test-runner
+    env:
+      - CGO_ENABLED=0
+    goarch: [amd64, arm64]
+    goos: [linux, darwin]
+
+archives:
+  - name_template: "{{ .Tag }}_{{ .Os }}_{{ .Arch }}"
+    format: tar.gz
diff --git a/test-runner/tests/build_image_test.rb b/test-runner/tests/build_image_test.rb
new file mode 100644
index 0000000..109dcb5
--- /dev/null
+++ b/test-runner/tests/build_image_test.rb
@@ -0,0 +1,168 @@
+require_relative "test_helper"
+
+require "timeout"
+
+class BuildImageTest < Minitest::Test
+  def setup
+    DatabaseHelper.clean
+
+    @repository = nil
+    @git_repository = nil
+    @build = nil
+
+    @fake_server_thread ||= Thread.new do
+      FakeServer.run!
+    end
+  end
+
+  def test_pushes_image
+    create_and_push_git_repository!("redis-ruby")
+
+    create_build!
+    run_script!
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+
+    assert_match(/Build successful/, output)
+    assert_equal "success", @build.reload.status
+    assert_match(/Build successful/, @build.reload.parsed_logs)
+  end
+
+  def test_streams_logs_to_test_run_too
+    create_and_push_git_repository!("redis-ruby")
+
+    create_build!
+    test_run = TestRun.create!(repository_id: @repository.id, id: SecureRandom.uuid, commit_sha: @build.commit_sha)
+
+    run_script!(test_run: test_run)
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+    Timeout.timeout(5) { `logstream -url #{test_run.local_logstream_url} run echo ended` }
+    test_run_output = Timeout.timeout(5) { `logstream -url #{test_run.local_logstream_url} follow` }
+
+    assert_match(/Build successful/, output)
+    assert_match(/Build successful/, test_run_output)
+    assert_equal "success", @build.reload.status
+    assert_match(/Build successful/, @build.reload.parsed_logs)
+  end
+
+  def test_handles_missing_buildpack
+    create_and_push_git_repository!("redis-ruby")
+
+    @git_repository.commit_changes_to_branch!(branch: "master") do |working_dir|
+      FileUtils.rm("#{working_dir}/codecrafters.yml")
+    end
+
+    create_build!
+    run_script!
+
+    assert_equal "failure", @build.reload.status
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+    assert_match(/Didn't find a codecrafters.yml file in your repository/, output)
+    assert_match(/Didn't find a codecrafters.yml file in your repository/, @build.reload.parsed_logs)
+  end
+
+  def test_build_failures
+    create_and_push_git_repository!("redis-rust")
+
+    @git_repository.commit_changes_to_branch!(branch: "master") do |working_dir|
+      `echo "abcd" > #{working_dir}/Cargo.toml`
+    end
+
+    create_build!
+    run_script!
+
+    assert_equal "failure", @build.reload.status
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+
+    assert_match(/Build failed/, output)
+    assert_match(/Build failed/, @build.reload.parsed_logs)
+  end
+
+  def test_build_failures_go
+    create_and_push_git_repository!("redis-go")
+
+    @git_repository.commit_changes_to_branch!(branch: "master") do |working_dir|
+      # Add an invalid module path to go.mod that will cause a build failure
+      `echo "module invalid_#" > #{working_dir}/go.mod`
+    end
+
+    create_build!
+    run_script!
+
+    assert_equal "failure", @build.reload.status
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+
+    assert_match(/Build failed/, output)
+    assert_match(/Build failed/, @build.reload.parsed_logs)
+    assert_match(/go: malformed module path "invalid_#"/, output)
+    assert_match(/go: malformed module path "invalid_#"/, @build.reload.parsed_logs)
+  end
+
+  def test_builds_for_specific_commit_sha
+    create_and_push_git_repository!("redis-rust")
+
+    old_commit_sha = @git_repository.head_commit_sha
+
+    # Should cause a build failure
+    new_commit_sha = @git_repository.commit_changes_to_branch!(branch: "testing") do |working_dir|
+      `echo "abcd" > #{working_dir}/Cargo.toml`
+    end
+
+    refute_equal old_commit_sha, new_commit_sha # make sure they're different
+
+    create_build!(commit_sha: new_commit_sha)
+
+    script_result = run_script!
+    assert_match(/Checking out commit #{new_commit_sha}/, script_result.out)
+
+    assert_equal "failure", @build.reload.status
+
+    output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+
+    assert_match(/Build failed/, output)
+    assert_match(/Build failed/, @build.reload.parsed_logs)
+  end
+
+  def test_removes_dockerignore_file
+    create_and_push_git_repository!("redis-ruby")
+
+    @git_repository.commit_changes_to_branch!(branch: "master") do |working_dir|
+      `touch #{working_dir}/.dockerignore`
+      `touch #{working_dir}/control.txt`
+    end
+
+    create_build!
+    run_script!
+    stream_output = Timeout.timeout(5) { `logstream -url #{@build.local_logstream_url} follow` }
+    
+    assert_match(/Build successful/, stream_output)
+    assert_equal "success", @build.reload.status
+    
+    ls_output = `docker run --rm registry.fly.io/test-depot-push:test-runner-tests ls -la /app`
+    refute_match(/.dockerignore/, ls_output, ".dockerignore should not exist in the built image")
+    assert_match(/control.txt/, ls_output, "control.txt should still exist in the built image")
+  end
+
+  def create_build!(commit_sha: nil)
+    commit_sha ||= @git_repository.head_commit_sha
+    @build = TestRunnerBuild.create!(test_runner: @repository.test_runners.first, id: SecureRandom.uuid, commit_sha: commit_sha)
+  end
+
+  def create_and_push_git_repository!(code_fixture_key)
+    @code_fixture = CodeFixtures.get(code_fixture_key)
+    buildpack = Buildpack.upsert_from_code_fixture!(@code_fixture)
+    @repository = Repository.create!(id: SecureRandom.uuid, course_slug: @code_fixture.fetch("course_slug"), language_slug: @code_fixture.fetch("language_slug"), buildpack: buildpack)
+    @git_repository = FakeGitRepository.new(@code_fixture.fetch("code_dir"), @repository)
+    @git_repository.push_to_git_daemon!
+  end
+
+  def run_script!(test_run: nil)
+    BuildImageCommandRunner
+      .new(git_repository: @git_repository, repository: @repository)
+      .run(build: @build, test_run: test_run)
+  end
+end
diff --git a/test-runner/tests/lib/build_image_command_runner.rb b/test-runner/tests/lib/build_image_command_runner.rb
new file mode 100644
index 0000000..def1886
--- /dev/null
+++ b/test-runner/tests/lib/build_image_command_runner.rb
@@ -0,0 +1,63 @@
+TEST_RUNNER_EXECUTABLE_PATH = File.expand_path("../../dist/main.out", __dir__)
+TEST_RUNNER_SOURCE_DIR = File.expand_path("../../", __dir__)
+TESTERS_DIR = File.expand_path("../fixtures/testers", __dir__)
+
+class BuildImageCommandRunner
+  attr_accessor :git_repository
+  attr_accessor :repository
+
+  def initialize(git_repository:, repository:)
+    self.git_repository = git_repository
+    self.repository = repository
+  end
+
+  def run(build:, test_run: nil)
+    tmp_dir = Dir.mktmpdir
+    tester_dir = TesterDownloader.new(course: OpenStruct.new(slug: repository.course_slug), testers_root_dir: TESTERS_DIR).download_if_needed
+
+    FileUtils.rm_rf(tmp_dir)
+    FileUtils.cp_r(git_repository.tmp_dir, tmp_dir)
+
+    test_runner_dir = Dir.mktmpdir
+    `cp #{TEST_RUNNER_EXECUTABLE_PATH} #{test_runner_dir}/test-runner`
+
+    dockerfile_handle = Tempfile.new
+    dockerfile_handle.write(repository.buildpack.processed_dockerfile_contents)
+    dockerfile_handle.close
+
+    command_parts = [
+      TEST_RUNNER_EXECUTABLE_PATH,
+      "build_image",
+      "--buildpack-slug='#{repository.buildpack.slug}'",
+      "--buildpack-dockerfile-path='#{dockerfile_handle.path}'",
+      "--build-id='#{build.id}'",
+      "--build-logstream-url='#{build.local_logstream_url}'",
+      "--codecrafters-server-url='http://localhost:6331'",
+      "--course-slug='#{repository.course_slug}'",
+      "--depot-token='#{ENV.fetch("DEPOT_TOKEN")}'",
+      "--depot-project='#{ENV.fetch("DEPOT_PROJECT")}'",
+      "--docker-image-name='test-depot-push'",
+      "--docker-image-tag='test-runner-tests'",
+      "--docker-registry-domain='registry.fly.io'",
+      "--docker-registry-password='#{ENV.fetch("FLY_ACCESS_TOKEN")}'",
+      "--docker-registry-username='x'",
+      "--repository-id='dummy-repository-id'",
+      "--repository-dir='#{tmp_dir}'",
+      "--test-runner-dir='#{test_runner_dir}'",
+      "--tester-dir='#{tester_dir}'"
+    ]
+
+    if build.commit_sha
+      command_parts << "-build-commit-sha #{build.commit_sha}"
+    end
+
+    if test_run
+      command_parts << "-build-test-run-logstream-url #{test_run.local_logstream_url}"
+    end
+
+    result = TTY::Command.new.run(command_parts.join(" "))
+    raise "Build image script failed. Stdout: #{result.out}. Stderr: #{result.err}" unless result.status == 0
+
+    result
+  end
+end
diff --git a/test-runner/tests/lib/buildpack_dockerfile_processor.rb b/test-runner/tests/lib/buildpack_dockerfile_processor.rb
new file mode 100644
index 0000000..bebaf56
--- /dev/null
+++ b/test-runner/tests/lib/buildpack_dockerfile_processor.rb
@@ -0,0 +1,88 @@
+# Mirrors what is available in core
+class BuildpackDockerfileProcessor
+  def self.append_line(contents, line)
+    lines = contents.lines
+    lines.push("\n")
+    lines.push(line)
+
+    lines.join
+  end
+
+  def self.build_postlude_lines
+    [
+      "# BEGIN GENERATED SECTION",
+      "WORKDIR /app",
+      "ARG CODECRAFTERS_SERVER_URL",
+      "ARG REPOSITORY_ID",
+      "ENV CODECRAFTERS_SERVER_URL=$CODECRAFTERS_SERVER_URL",
+      "ENV REPOSITORY_ID=$REPOSITORY_ID",
+      "COPY . /app",
+      grouped_run(
+        "mkdir -p /var/opt",
+        # Copy test runner binary
+        "mv /app/test-runner/test-runner /var/opt/test-runner",
+        "chmod +x /var/opt/test-runner",
+        "rm -rf /app/test-runner",
+        # Copy tester binary
+        "mv /app/tester /var/opt/tester",
+        # Ensure all files are readable by everyone (some languages have files only readable by user)
+        "chmod -R +rw /app",
+        "sh -c '(test -d /app-cached && chmod -R ugo+rwx /app-cached) || true'"
+      ),
+      "# END GENERATED SECTION"
+    ]
+  end
+
+  def self.build_prelude_lines(from_line)
+    [
+      "# BEGIN GENERATED SECTION",
+
+      # Git is required to pull repository changes. I don't think we need curl anymore, not sure...
+      case from_line
+      when /alpine/
+        "RUN apk add --update-cache --upgrade git curl"
+      when /buster/, /slim/, /focal/, /bullseye/, /bookworm/
+        "RUN apt-get update && apt-get install -y git curl"
+      when /dart/
+        "RUN apt-get update && apt-get install -y git curl" # Dart doesn't have OS type in its FROM line
+      else
+        raise "Unknown from_line: #{from_line}"
+      end,
+
+      "CMD [\"/var/opt/test-runner\", \"run_tests\"]",
+      "ENV TESTER_DIR=/var/opt/tester",
+      "# END GENERATED SECTION"
+    ]
+  end
+
+  def self.grouped_run(*commands)
+    ("RUN " + commands.join(" && "))
+  end
+
+  def self.insert_line(contents, index, line)
+    lines = contents.lines
+    lines.insert(index, line + "\n")
+    lines.join
+  end
+
+  def self.process(dockerfile_contents)
+    lines = dockerfile_contents.lines.map(&:strip)
+    from_line_index = lines.index { |line| line.start_with?("FROM") }
+
+    raise "No FROM line found. Dockerfile: #{dockerfile_contents}" unless from_line_index.present?
+
+    from_line = lines[from_line_index]
+
+    first_user_line_index = lines.index { |line| line.start_with?("USER") }
+
+    # If there's a USER line, we'll insert the prelude after the first USER line. Else, we'll insert it after the FROM line.
+    pivot_index = first_user_line_index || from_line_index
+
+    [
+      lines[0..pivot_index].join("\n"),
+      build_prelude_lines(from_line).join("\n"),
+      lines[(pivot_index + 1)..].join("\n"),
+      build_postlude_lines.join("\n")
+    ].join("\n\n").strip.gsub(/\n\n\n+/, "\n\n") + "\n"
+  end
+end
diff --git a/test-runner/tests/lib/code_fixtures.rb b/test-runner/tests/lib/code_fixtures.rb
new file mode 100644
index 0000000..4468b8f
--- /dev/null
+++ b/test-runner/tests/lib/code_fixtures.rb
@@ -0,0 +1,38 @@
+module CodeFixtures
+  repository_root = File.expand_path("../../", __dir__)
+
+  DB = {
+    "redis-ruby" => {
+      "dockerfile_contents" => File.read(File.join(repository_root, "tests/fixtures/dockerfiles/redis-ruby-3.3.Dockerfile")),
+      "buildpack_slug" => "ruby-3.3",
+      "code_dir" => File.join(repository_root, "tests/fixtures/redis-ruby-pass-stage-1"),
+      "course_slug" => "redis",
+      "language_slug" => "ruby"
+    },
+    "redis-rust" => {
+      "dockerfile_contents" => File.read(File.join(repository_root, "tests/fixtures/dockerfiles/redis-rust-1.88.Dockerfile")),
+      "buildpack_slug" => "rust-1.88",
+      "code_dir" => File.join(repository_root, "tests/fixtures/redis-rust-pass-stage-1"),
+      "course_slug" => "redis",
+      "language_slug" => "rust"
+    },
+    "redis-go" => {
+      "dockerfile_contents" => File.read(File.join(repository_root, "tests/fixtures/dockerfiles/redis-go-1.24.Dockerfile")),
+      "buildpack_slug" => "go-1.24",
+      "code_dir" => File.join(repository_root, "tests/fixtures/redis-go-pass-stage-1"),
+      "course_slug" => "redis",
+      "language_slug" => "go"
+    },
+    "sqlite-python" => {
+      "dockerfile_contents" => File.read(File.join(repository_root, "tests/fixtures/dockerfiles/sqlite-python-3.13.Dockerfile")),
+      "buildpack_slug" => "python-3.13",
+      "code_dir" => File.join(repository_root, "tests/fixtures/sqlite-python-pass-stage-1"),
+      "course_slug" => "sqlite",
+      "language_slug" => "python"
+    }
+  }
+
+  def self.get(code_config_key)
+    DB.fetch(code_config_key)
+  end
+end
diff --git a/test-runner/tests/lib/database_helper.rb b/test-runner/tests/lib/database_helper.rb
new file mode 100644
index 0000000..83be65b
--- /dev/null
+++ b/test-runner/tests/lib/database_helper.rb
@@ -0,0 +1,10 @@
+module DatabaseHelper
+  def self.clean
+    TestRunResult.delete_all
+    TestRun.delete_all
+    TestRunnerBuild.delete_all
+    Submission.delete_all
+    Repository.delete_all
+    # TestRunnerInfrastructure
+  end
+end
diff --git a/test-runner/tests/lib/db/models/application_record.rb b/test-runner/tests/lib/db/models/application_record.rb
new file mode 100644
index 0000000..6962fb6
--- /dev/null
+++ b/test-runner/tests/lib/db/models/application_record.rb
@@ -0,0 +1,7 @@
+class ApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
+
+  before_validation do
+    self.id ||= SecureRandom.uuid
+  end
+end
diff --git a/test-runner/tests/lib/db/models/buildpack.rb b/test-runner/tests/lib/db/models/buildpack.rb
new file mode 100644
index 0000000..edf58de
--- /dev/null
+++ b/test-runner/tests/lib/db/models/buildpack.rb
@@ -0,0 +1,15 @@
+class Buildpack < ApplicationRecord
+  validates_presence_of :course_slug
+  validates_presence_of :language_slug
+  validates_presence_of :slug
+
+  def self.upsert_from_code_fixture!(code_fixture)
+    buildpack = find_or_initialize_by(slug: code_fixture.fetch("buildpack_slug"))
+    buildpack.course_slug = code_fixture.fetch("course_slug")
+    buildpack.language_slug = code_fixture.fetch("language_slug")
+    buildpack.processed_dockerfile_contents = BuildpackDockerfileProcessor.process(code_fixture.fetch("dockerfile_contents"))
+    buildpack.save!
+
+    buildpack
+  end
+end
diff --git a/test-runner/tests/lib/db/models/repository.rb b/test-runner/tests/lib/db/models/repository.rb
new file mode 100644
index 0000000..b4055e3
--- /dev/null
+++ b/test-runner/tests/lib/db/models/repository.rb
@@ -0,0 +1,29 @@
+class Repository < ActiveRecord::Base
+  belongs_to :buildpack
+
+  has_many :test_runs
+  has_many :test_runners
+
+  validates_presence_of :course_slug
+  validates_presence_of :language_slug
+
+  after_create do
+    test_runners.create!
+  end
+
+  def clone_url
+    "http://host.docker.internal:6332/#{id}"
+  end
+
+  def local_clone_url
+    "http://localhost:6332/#{id}"
+  end
+
+  def secret_id
+    id # temp
+  end
+
+  def test_runner
+    @test_runner ||= test_runners.first # Caching this so that we can mutate ID
+  end
+end
diff --git a/test-runner/tests/lib/db/models/submission.rb b/test-runner/tests/lib/db/models/submission.rb
new file mode 100644
index 0000000..ba70b0e
--- /dev/null
+++ b/test-runner/tests/lib/db/models/submission.rb
@@ -0,0 +1,10 @@
+class Submission < ApplicationRecord
+  belongs_to :repository
+  has_many :test_runs
+
+  validates_presence_of :commit_sha
+
+  def logstream_url
+    test_runs.first.logstream_url
+  end
+end
diff --git a/test-runner/tests/lib/db/models/test_run.rb b/test-runner/tests/lib/db/models/test_run.rb
new file mode 100644
index 0000000..cf826f1
--- /dev/null
+++ b/test-runner/tests/lib/db/models/test_run.rb
@@ -0,0 +1,28 @@
+class TestRun < ApplicationRecord
+  ALL_STATUSES = %w[
+    pending
+    success
+    failure
+    error
+    cancelled
+  ]
+
+  enum status: ALL_STATUSES.zip(ALL_STATUSES).to_h
+
+  belongs_to :repository
+  belongs_to :submission, optional: true
+
+  has_many :results, class_name: "TestRunResult"
+
+  before_validation do
+    self.status ||= "pending"
+  end
+
+  def logstream_url
+    "redis://host.docker.internal:6334/test-run-#{id}"
+  end
+
+  def local_logstream_url
+    "redis://localhost:6334/test-run-#{id}"
+  end
+end
diff --git a/test-runner/tests/lib/db/models/test_run_result.rb b/test-runner/tests/lib/db/models/test_run_result.rb
new file mode 100644
index 0000000..d535e6c
--- /dev/null
+++ b/test-runner/tests/lib/db/models/test_run_result.rb
@@ -0,0 +1,16 @@
+class TestRunResult < ActiveRecord::Base
+  ALL_STATUSES = %w[
+    success
+    failure
+    error
+    cancelled
+  ]
+
+  enum :status, ALL_STATUSES.zip(ALL_STATUSES).to_h
+
+  belongs_to :test_run
+
+  def parsed_logs
+    Base64.decode64(logs_base64)
+  end
+end
diff --git a/test-runner/tests/lib/db/models/test_runner.rb b/test-runner/tests/lib/db/models/test_runner.rb
new file mode 100644
index 0000000..6483da1
--- /dev/null
+++ b/test-runner/tests/lib/db/models/test_runner.rb
@@ -0,0 +1,15 @@
+class TestRunner < ApplicationRecord
+  ALL_MACHINE_STATUSES = [
+    "stopped",
+    "starting",
+    "running"
+  ]
+
+  enum machine_status: ALL_MACHINE_STATUSES.zip(ALL_MACHINE_STATUSES).to_h
+
+  belongs_to :repository
+
+  before_validation do
+    self.machine_status ||= "starting"
+  end
+end
diff --git a/test-runner/tests/lib/db/models/test_runner_build.rb b/test-runner/tests/lib/db/models/test_runner_build.rb
new file mode 100644
index 0000000..0cae8fb
--- /dev/null
+++ b/test-runner/tests/lib/db/models/test_runner_build.rb
@@ -0,0 +1,32 @@
+class TestRunnerBuild < ApplicationRecord
+  ALL_STATUSES = %w[
+    not_started
+    in_progress
+    success
+    failure
+    error
+  ]
+
+  enum status: ALL_STATUSES.zip(ALL_STATUSES).to_h
+
+  belongs_to :test_runner
+
+  validates_presence_of :commit_sha
+  validates_presence_of :status
+
+  before_validation do
+    self.status ||= "not_started"
+  end
+
+  def logstream_url
+    "redis://host.docker.internal:6334/test-runner-build-#{id}"
+  end
+
+  def local_logstream_url
+    "redis://localhost:6334/test-runner-build-#{id}"
+  end
+
+  def parsed_logs
+    Base64.strict_decode64(logs_base64)
+  end
+end
diff --git a/test-runner/tests/lib/db/schema.rb b/test-runner/tests/lib/db/schema.rb
new file mode 100644
index 0000000..7a1abe4
--- /dev/null
+++ b/test-runner/tests/lib/db/schema.rb
@@ -0,0 +1,56 @@
+ActiveRecord::Schema.define do
+  create_table "buildpacks", id: :string, force: :cascade do |t|
+    t.string "course_slug", null: false
+    t.string "language_slug", null: false
+    t.string "slug", null: false
+    t.string "processed_dockerfile_contents", null: false
+  end
+
+  create_table "repositories", id: :string, force: :cascade do |t|
+    t.string "course_slug", null: false
+    t.string "language_slug", null: false
+    t.string "buildpack_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  create_table "test_runs", id: :string, force: :cascade do |t|
+    t.string "repository_id", null: false
+    t.string "submission_id"
+    t.string "commit_sha", null: false
+    t.string "status", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  create_table "test_run_results", id: :string, force: :cascade do |t|
+    t.string "test_run_id", null: false
+    t.string "logs_base64"
+    t.string "status"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  create_table "test_runner_builds", id: :string, force: :cascade do |t|
+    t.string "test_runner_id", null: false
+    t.string "commit_sha" # can be null at the start?
+    t.string "status", null: false
+    t.string "logs_base64"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
+  create_table "test_runners", id: :string, force: :cascade do |t|
+    t.string "repository_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.string "machine_status", null: false
+  end
+
+  create_table "submissions", id: :string, force: :cascade do |t|
+    t.string "repository_id", null: false
+    t.string "commit_sha", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+end
diff --git a/test-runner/tests/lib/fake_git_repository.rb b/test-runner/tests/lib/fake_git_repository.rb
new file mode 100644
index 0000000..bdfb56e
--- /dev/null
+++ b/test-runner/tests/lib/fake_git_repository.rb
@@ -0,0 +1,90 @@
+class FakeGitRepository
+  attr_accessor :tmp_dir
+  attr_accessor :repository
+
+  def initialize(copy_from_dir, repository)
+    @tmp_dir = Dir.mktmpdir
+    @repository = repository
+
+    FileUtils.rm_rf(tmp_dir)
+    FileUtils.cp_r(copy_from_dir, tmp_dir)
+
+    commands = [
+      "git -C #{tmp_dir} init ",
+      "git -C #{tmp_dir} checkout -b master",
+      "git -C #{tmp_dir} add  .",
+      "git -C #{tmp_dir} commit -m \"testing [skip ci]\"",
+      "git -C #{tmp_dir} remote add origin #{repository.local_clone_url}"
+    ]
+
+    commands.each do |command|
+      output = `#{command} 2>&1`
+      raise "Git command failed: #{command}. Output: #{output}" unless $?.success?
+    end
+  end
+
+  def commit_changes_to_branch!(branch: "testing", &block)
+    block.call(tmp_dir)
+
+    commands = [
+      "git -C #{tmp_dir} checkout -b #{branch} || git -C #{tmp_dir} checkout #{branch}",
+      "git -C #{tmp_dir} add  .",
+      "git -C #{tmp_dir} commit -m \"changes [skip ci]\""
+    ]
+
+    commands.each do |command|
+      output = `#{command} 2>&1`
+      raise "Git command failed: #{command}. Output: #{output}" unless $?.success?
+    end
+
+    commit_sha = head_commit_sha
+
+    push_to_git_daemon!(branch: branch)
+
+    commands = [
+      "git -C #{tmp_dir} checkout -f master"
+    ]
+
+    commands.each do |command|
+      output = `#{command} 2>&1`
+      raise "Git command failed: #{command}. Output: #{output}" unless $?.success?
+    end
+
+    commit_sha
+  end
+
+  def head_commit_sha
+    `git -C #{tmp_dir} rev-parse HEAD`.strip
+  end
+
+  def push_to_git_daemon!(branch: "master")
+    GitApiGateway.new.create_repository(repository.id)
+
+    result = TTY::Command.new.run("git -C #{tmp_dir} push -f -u origin #{branch}")
+    raise "Git command failed: #{command}. Stdout: #{result.out}, Stderr: #{result.err}" unless result.status == 0
+
+    result
+  end
+
+  def push_changes_to_master!(&block)
+    block.call(tmp_dir)
+
+    commands = [
+      "git -C #{tmp_dir} add  .",
+      "git -C #{tmp_dir} commit --allow-empty -m \"changes\""
+    ]
+
+    commands.each do |command|
+      output = `#{command} 2>&1`
+      raise "Git command failed: #{command}. Output: #{output}" unless $?.success?
+    end
+
+    push_to_git_daemon!(branch: "master")
+  end
+
+  def set_remote_url(remote_url)
+    command = "git -C #{tmp_dir} remote set-url origin #{remote_url}"
+    result = TTY::Command.new.run(command)
+    raise "Git command failed: #{command}. Stdout: #{result.out}, Stderr: #{result.err}" unless result.status == 0
+  end
+end
diff --git a/test-runner/tests/lib/fake_server.rb b/test-runner/tests/lib/fake_server.rb
new file mode 100644
index 0000000..41c30b9
--- /dev/null
+++ b/test-runner/tests/lib/fake_server.rb
@@ -0,0 +1,196 @@
+require "sinatra/base"
+
+class FakeServer < Sinatra::Base
+  set :port, 6331
+  set :bind, "0.0.0.0"
+
+  error do
+    content_type :json
+    status 500
+
+    {
+      error: env["sinatra.error"].message,
+      backtrace: env["sinatra.error"].backtrace.join("\n")
+    }.to_json
+  end
+
+  get "/" do
+    "hello"
+  end
+
+  # --- Public Interface Starts ---
+
+  post "/services/test_runner/create_submission" do
+    halt 400, {error: "invalid content type"}.to_json unless request.content_type == "application/json"
+    json = JSON.parse(request.body.read)
+
+    repository_id = json.fetch("repository_id")
+    repository = Repository.find_by(id: repository_id) # should actually use secret_id
+
+    if !repository
+      halt 400, "repository not found"
+    end
+
+    if repository.id == "no-paid-access"
+      halt 200, {is_error: true, error_message: "This stage requires a CodeCrafters membership"}.to_json
+    end
+
+    submission = Submission.create!(commit_sha: json.fetch("commit_sha"), repository: repository)
+    test_run = submission.test_runs.create!(commit_sha: json.fetch("commit_sha"), repository: repository)
+
+    Timeout.timeout(5) { `logstream -url #{test_run.local_logstream_url} run echo test-run-success` }
+
+    build = TestRunnerBuild.where(test_runner: repository.test_runners, status: "in_progress").first
+
+    halt 200, {
+      id: submission.id,
+      actions: SubmissionTestRunnerActionsBuilder.build(submission: submission, test_run: test_run, pending_build: build).map(&:as_json_for_test_runner)
+    }.to_json
+  end
+
+  get "/services/test_runner/fetch_submission" do
+    _submission = Submission.find(params.fetch("submission_id"))
+
+    halt 200, {status: "success"}.to_json
+  end
+
+  get "/services/test_runner/fetch_test_runner_build" do
+    test_runner_build = TestRunnerBuild.find_by_id(params.fetch("test_runner_build_id"))
+
+    if !test_runner_build
+      puts "build not found, id: #{params.fetch("id")}"
+      halt 404, {error: "build not found"}.to_json
+    end
+
+    halt 200, {status: test_runner_build.status}.to_json
+  end
+
+  post "/services/test_runner/finalize_test_runner_build" do
+    halt 400, {error: "invalid content type"}.to_json unless request.content_type == "application/json"
+
+    json = JSON.parse(request.body.read)
+
+    build = TestRunnerBuild.find_by(id: json.fetch("test_runner_build_id"))
+    halt 404, {error: "build not found"}.to_json if build.nil?
+
+    build.update!(status: json.fetch("status"), logs_base64: json.fetch("logs_base64"))
+  end
+
+  post "/services/test_runner/reserve_test_run" do
+    test_runner_id = params.fetch("test_runner_id")
+    halt 400, {error: "test_runner_id is required"}.to_json if test_runner_id.strip.empty?
+
+    test_runner = TestRunner.find_by(id: test_runner_id)
+    halt 400, {error: "test runner not found"}.to_json unless test_runner
+
+    test_runner.update!(machine_status: "running")
+
+    test_run = test_runner.repository.test_runs.pending.order(created_at: :asc).first
+
+    if test_run && test_run.repository.course_slug.eql?("redis")
+      {
+        test_run: {
+          id: test_run.id,
+          commit_sha: test_run.commit_sha,
+          test_cases_json: [{slug: "jm1", tester_log_prefix: "tester::#JM1", title: "Stage #JM1 Bind to a port"}].to_json,
+          logstream_url: test_run.logstream_url
+        }
+      }.to_json
+    elsif test_run && test_run.repository.course_slug.eql?("sqlite")
+      {
+        test_run: {
+          id: test_run.id,
+          commit_sha: test_run.commit_sha,
+          test_cases_json: [{slug: "dr6", tester_log_prefix: "tester::#DR6", title: "Stage #DR6 Print page size"}].to_json,
+          logstream_url: test_run.logstream_url
+        }
+      }.to_json
+    else
+      halt 200, {should_retry: false}.to_json
+    end
+  end
+
+  post "/services/test_runner/create_test_run_result" do
+    halt 400, {error: "invalid content type"}.to_json unless request.content_type == "application/json"
+
+    json = JSON.parse(request.body.read)
+
+    test_run = TestRun.find_by(id: json.fetch("test_run_id"))
+    test_runner = TestRunner.find_by(id: json.fetch("test_runner_id"))
+
+    halt 404, {error: "test run not found"}.to_json if test_run.nil?
+    halt 404, {error: "test runner not found"}.to_json if test_runner.nil?
+    halt 400, {error: "repository mismatch"}.to_json unless test_run.repository.eql?(test_runner.repository)
+
+    # This is a sanity check, production is actually forgiving of this case
+    halt 400, {error: "test runner not running"}.to_json unless test_runner.machine_status.eql?("running")
+
+    TestRun.transaction do
+      result = test_run.results.create!(
+        id: SecureRandom.uuid,
+        status: json.fetch("status"),
+        logs_base64: json.fetch("logs_base64")
+      )
+
+      test_run.update!(status: result.status)
+    end
+  end
+
+  post "/services/test_runner/rebuild_for_test_run" do
+    halt 400, {error: "invalid content type"}.to_json unless request.content_type == "application/json"
+
+    json = JSON.parse(request.body.read)
+
+    test_run = TestRun.find_by(id: json.fetch("test_run_id"))
+    test_runner = TestRunner.find_by(id: json.fetch("test_runner_id"))
+
+    halt 404, {error: "test run not found"}.to_json if test_run.nil?
+    halt 404, {error: "test runner not found"}.to_json if test_runner.nil?
+    halt 400, {error: "repository mismatch"}.to_json unless test_run.repository.eql?(test_runner.repository)
+
+    # This is a sanity check, production is actually forgiving of this case
+    halt 400, {error: "test runner not running"}.to_json unless test_runner.machine_status.eql?("running")
+
+    test_runner.update!(machine_status: "starting") # Reprovisioning would set the start to "starting"
+
+    build = TestRunnerBuild.create!(test_runner: test_run.repository.test_runner, status: "not_started", commit_sha: test_run.commit_sha)
+
+    Thread.new do
+      Timeout.timeout(5) { `logstream -url #{build.local_logstream_url} run echo build-success` }
+      sleep 1
+      build.update!(status: "success", logs_base64: Base64.strict_encode64("build-success"))
+    end
+
+    {
+      id: build.id,
+      commit_sha: build.commit_sha,
+      logstream_url: build.logstream_url
+    }.to_json
+  end
+
+  post "/services/test_runner/report_shutdown" do
+    halt 400, {error: "invalid content type"}.to_json unless request.content_type == "application/json"
+
+    json = JSON.parse(request.body.read)
+
+    test_runner = TestRunner.find_by(id: json.fetch("test_runner_id"))
+    halt 404, {error: "test runner not found"}.to_json if test_runner.nil?
+
+    # This is a sanity check, production is actually forgiving of this case
+    halt 400, {error: "test runner not running"}.to_json unless test_runner.machine_status.eql?("running")
+
+    test_runner.update!(machine_status: "stopped")
+
+    "success"
+  end
+
+  # --- Public Interface Ends ---
+
+  post "/_debug/create_test_run" do
+    repository_id = params.fetch("repository_id")
+    test_run_id = params.fetch("test_run_id")
+    TEST_RUNS[repository_id] = test_run_id
+
+    "created test run #{test_run_id} for repository #{repository_id}"
+  end
+end
diff --git a/test-runner/tests/lib/git_api_gateway.rb b/test-runner/tests/lib/git_api_gateway.rb
new file mode 100644
index 0000000..2e50fa0
--- /dev/null
+++ b/test-runner/tests/lib/git_api_gateway.rb
@@ -0,0 +1,43 @@
+# Copied from core
+class GitApiGateway
+  def create_repository(repository_name)
+    response = HTTParty.post(
+      "http://localhost:6333/api/v1/repositories",
+      body: {
+        name: repository_name
+      }.to_json,
+      headers: {"Content-Type" => "application/json"}
+    )
+
+    if response.code.eql?(200)
+      response.parsed_response
+    else
+      raise "Error creating repository. Status: #{response.code}, Body: #{response.body}"
+    end
+  end
+
+  def delete_repository(repository_name)
+    response = HTTParty.delete("http://localhost:6333/api/v1/repositories/#{repository_name}")
+
+    if response.code.eql?(200)
+      response.parsed_response
+    elsif response.code.eql?(404)
+      Sentry.capture_message("Repository not found when deleting", extra: {repository_name: repository_name})
+      nil # Idempotency
+    else
+      raise "Error deleting repository. Status: #{response.code}, Body: #{response.body}"
+    end
+  end
+
+  def fetch_commit(repository_id, commit_sha)
+    response = HTTParty.get("http://localhost:6333/api/v1/repositories/#{repository_id}/commits/#{commit_sha}")
+
+    if response.code.eql?(200)
+      response.parsed_response
+    elsif response.code.eql?(404)
+      nil
+    else
+      raise "Error fetching commit. Status: #{response.code}, Body: #{response.body}"
+    end
+  end
+end
diff --git a/test-runner/tests/lib/run_tests_command_runner.rb b/test-runner/tests/lib/run_tests_command_runner.rb
new file mode 100644
index 0000000..88067fa
--- /dev/null
+++ b/test-runner/tests/lib/run_tests_command_runner.rb
@@ -0,0 +1,53 @@
+TEST_RUNNER_LINUX_EXECUTABLE_PATH = File.expand_path("../../dist/main-linux.out", __dir__)
+TESTERS_DIR = File.expand_path("../fixtures/testers", __dir__)
+
+class RunTestsCommandRunner
+  attr_accessor :git_repository
+  attr_accessor :repository
+
+  def initialize(git_repository:, repository:)
+    self.git_repository = git_repository
+    self.repository = repository
+  end
+
+  def dockerfile_path
+    repository.dockerfile_path(git_repository)
+  end
+
+  def run
+    tmp_dir = Dir.mktmpdir
+    tester_dir = TesterDownloader.new(course: OpenStruct.new(slug: repository.course_slug), testers_root_dir: TESTERS_DIR).download_if_needed
+
+    FileUtils.rm_rf(tmp_dir)
+    FileUtils.cp_r(git_repository.tmp_dir, tmp_dir)
+
+    dockerfile_handle = Tempfile.new
+    dockerfile_handle.write(repository.buildpack.processed_dockerfile_contents)
+    dockerfile_handle.close
+
+    puts File.read(dockerfile_handle.path)
+
+    # Required for build
+    FileUtils.mkdir_p("#{tmp_dir}/test-runner")
+    FileUtils.cp(TEST_RUNNER_LINUX_EXECUTABLE_PATH, "#{tmp_dir}/test-runner/test-runner")
+    FileUtils.cp_r(tester_dir, "#{tmp_dir}/tester")
+
+    result = TTY::Command.new.run("docker build --quiet -t test_runner_test_image -f #{dockerfile_handle.path} #{tmp_dir}")
+    raise "Docker build failed. Stdout: #{result.out}. Stderr: #{result.err}" unless result.status == 0
+
+    command_parts = [
+      "docker run",
+      "-e CODECRAFTERS_SERVER_URL=http://host.docker.internal:6331",
+      "-e CODECRAFTERS_TEST_RUNNER_ID=#{repository.test_runner.id}",
+      "-e REPOSITORY_ID=#{repository.id}",
+      "--add-host=host.docker.internal:host-gateway", # Required for CI, works by default on macOS
+      "--rm ",
+      "test_runner_test_image"
+    ]
+
+    result = TTY::Command.new.run(command_parts.join(" "))
+    raise "Test runner script failed. Stdout: #{result.out}. Stderr: #{result.err}" unless result.status == 0
+
+    result
+  end
+end
diff --git a/test-runner/tests/lib/submission_test_runner_actions_builder.rb b/test-runner/tests/lib/submission_test_runner_actions_builder.rb
new file mode 100644
index 0000000..5308693
--- /dev/null
+++ b/test-runner/tests/lib/submission_test_runner_actions_builder.rb
@@ -0,0 +1,62 @@
+# This is a simplified version of the SubmissionTestRunnerActionsBuilder in core
+class SubmissionTestRunnerActionsBuilder
+  def self.build(submission:, test_run:, pending_build:)
+    actions = []
+
+    if pending_build.present?
+      actions << TestRunnerActions::PrintMessage.green("Welcome back! Note that this might take a while...")
+    end
+
+    actions << TestRunnerActions::PrintMessage.plain("")
+
+    # If there's a panding build present, stream build logs first
+    if pending_build
+      actions << TestRunnerActions::PrintMessage.plain("Streaming build logs...")
+      actions << TestRunnerActions::PrintMessage.plain("")
+      actions << TestRunnerActions::StreamLogs.from_url(pending_build.local_logstream_url)
+
+      on_success_actions = [
+        TestRunnerActions::Sleep.milliseconds(1000)
+      ]
+
+      on_failure_actions = [
+        TestRunnerActions::PrintMessage.red(""),
+        TestRunnerActions::PrintMessage.red("Looks like your codebase failed to build."),
+        TestRunnerActions::PrintMessage.red("If you think this is a CodeCrafters error, please let us know at hello@codecrafters.io."),
+        TestRunnerActions::PrintMessage.red(""),
+        TestRunnerActions::Terminate.with_exit_code(0)
+      ]
+
+      actions << TestRunnerActions::AwaitTerminalBuildStatus.for_build_id(
+        pending_build.id,
+        on_success_actions: on_success_actions,
+        on_failure_actions: on_failure_actions
+      )
+    end
+
+    actions << TestRunnerActions::PrintMessage.plain("")
+    actions << TestRunnerActions::PrintMessage.plain("Running tests on your code. Logs should appear shortly...")
+    actions << TestRunnerActions::PrintMessage.plain("")
+
+    # Small delay, perceive logs as streamed
+    actions << TestRunnerActions::Sleep.milliseconds(200)
+    actions << TestRunnerActions::StreamLogs.from_url(test_run.local_logstream_url)
+    actions << TestRunnerActions::PrintMessage.plain("")
+
+    actions << TestRunnerActions::AwaitTerminalSubmissionStatus.for_submission_id(
+      submission.id,
+      on_success_actions: [
+        TestRunnerActions::PrintMessage.plain(""),
+        TestRunnerActions::PrintMessage.plain("Test passed. Congrats!"),
+        TestRunnerActions::PrintMessage.plain("")
+      ],
+      on_failure_actions: [
+        TestRunnerActions::PrintMessage.plain(""),
+        TestRunnerActions::PrintMessage.plain("Tests failed! Oops."),
+        TestRunnerActions::PrintMessage.plain("")
+      ]
+    )
+
+    actions
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb b/test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb
new file mode 100644
index 0000000..92cfc2b
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb
@@ -0,0 +1,17 @@
+class TestRunnerActions::AwaitTerminalBuildStatus < TestRunnerActions::Base
+  attr_accessor :build_id
+  attr_accessor :on_success_actions
+  attr_accessor :on_failure_actions
+
+  validates_presence_of :build_id
+  validates_presence_of :on_success_actions
+  validates_presence_of :on_failure_actions
+
+  def args_for_test_runner
+    [:build_id, :on_success_actions, :on_failure_actions]
+  end
+
+  def self.for_build_id(build_id, on_success_actions:, on_failure_actions:)
+    new(build_id: build_id, on_success_actions: on_success_actions, on_failure_actions: on_failure_actions)
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb b/test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb
new file mode 100644
index 0000000..d3095ea
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb
@@ -0,0 +1,17 @@
+class TestRunnerActions::AwaitTerminalSubmissionStatus < TestRunnerActions::Base
+  attr_accessor :submission_id
+  attr_accessor :on_success_actions
+  attr_accessor :on_failure_actions
+
+  validates_presence_of :submission_id
+  validates_presence_of :on_success_actions
+  validates_presence_of :on_failure_actions
+
+  def args_for_test_runner
+    [:submission_id, :on_success_actions, :on_failure_actions]
+  end
+
+  def self.for_submission_id(submission_id, on_success_actions:, on_failure_actions:)
+    new(submission_id: submission_id, on_success_actions: on_success_actions, on_failure_actions: on_failure_actions)
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/base.rb b/test-runner/tests/lib/test_runner_actions/base.rb
new file mode 100644
index 0000000..0af0063
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/base.rb
@@ -0,0 +1,29 @@
+class TestRunnerActions::Base
+  include ActiveModel::Model
+
+  def as_json_for_test_runner
+    {
+      type: self.class.name.demodulize.underscore,
+      args: args_for_test_runner.map { |arg|
+        value = send(arg)
+
+        [
+          arg,
+          if value.is_a?(TestRunnerActions::Base)
+            value.as_json_for_test_runner
+          elsif value.is_a?(Array) && value.all? { |v| v.is_a?(TestRunnerActions::Base) }
+            value.map { |v| v.as_json_for_test_runner }
+          else
+            value
+          end
+        ]
+      }.to_h
+    }
+  end
+
+  def initialize(**attributes)
+    super(attributes)
+
+    validate! # Ensure we don't construct an invalid action
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/print_message.rb b/test-runner/tests/lib/test_runner_actions/print_message.rb
new file mode 100644
index 0000000..f9bcddb
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/print_message.rb
@@ -0,0 +1,33 @@
+class TestRunnerActions::PrintMessage < TestRunnerActions::Base
+  attr_accessor :color
+  attr_accessor :text
+
+  validates_presence_of :color
+  validates_presence_of :text, allow_blank: true
+
+  validates_inclusion_of :color, in: %w[green red yellow blue plain]
+
+  def args_for_test_runner
+    [:color, :text]
+  end
+
+  def self.blue(message)
+    new(color: "blue", text: message)
+  end
+
+  def self.green(message)
+    new(color: "green", text: message)
+  end
+
+  def self.plain(message)
+    new(color: "plain", text: message)
+  end
+
+  def self.red(message)
+    new(color: "red", text: message)
+  end
+
+  def self.yellow(message)
+    new(color: "yellow", text: message)
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/sleep.rb b/test-runner/tests/lib/test_runner_actions/sleep.rb
new file mode 100644
index 0000000..ce70c5f
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/sleep.rb
@@ -0,0 +1,18 @@
+class TestRunnerActions::Sleep < TestRunnerActions::Base
+  attr_accessor :duration_in_milliseconds
+
+  validates_presence_of :duration_in_milliseconds
+  validates_numericality_of :duration_in_milliseconds, greater_than: 0
+
+  def args_for_test_runner
+    [:duration_in_milliseconds]
+  end
+
+  def self.milliseconds(duration_in_milliseconds)
+    new(duration_in_milliseconds: duration_in_milliseconds)
+  end
+
+  def self.seconds(duration_in_seconds)
+    new(duration_in_milliseconds: duration_in_seconds * 1000)
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/stream_logs.rb b/test-runner/tests/lib/test_runner_actions/stream_logs.rb
new file mode 100644
index 0000000..ee3c099
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/stream_logs.rb
@@ -0,0 +1,13 @@
+class TestRunnerActions::StreamLogs < TestRunnerActions::Base
+  attr_accessor :logstream_url
+
+  validates_presence_of :logstream_url
+
+  def args_for_test_runner
+    [:logstream_url]
+  end
+
+  def self.from_url(logstream_url)
+    new(logstream_url: logstream_url)
+  end
+end
diff --git a/test-runner/tests/lib/test_runner_actions/terminate.rb b/test-runner/tests/lib/test_runner_actions/terminate.rb
new file mode 100644
index 0000000..3b9a61e
--- /dev/null
+++ b/test-runner/tests/lib/test_runner_actions/terminate.rb
@@ -0,0 +1,13 @@
+class TestRunnerActions::Terminate < TestRunnerActions::Base
+  attr_accessor :exit_code
+
+  validates_presence_of :exit_code
+
+  def args_for_test_runner
+    [:exit_code]
+  end
+
+  def self.with_exit_code(exit_code)
+    new(exit_code: exit_code)
+  end
+end
diff --git a/test-runner/tests/lib/tester_downloader.rb b/test-runner/tests/lib/tester_downloader.rb
new file mode 100644
index 0000000..0f7fcaa
--- /dev/null
+++ b/test-runner/tests/lib/tester_downloader.rb
@@ -0,0 +1,54 @@
+class TesterDownloader
+  def initialize(course:, testers_root_dir:)
+    @course = course
+    @testers_root_dir = testers_root_dir
+  end
+
+  def download_if_needed
+    return tester_dir if File.exist?(tester_dir)
+
+    compressed_file_path = File.join(@testers_root_dir, "#{@course.slug}.tar.gz")
+
+    FileUtils.mkdir_p(@testers_root_dir)
+
+    File.open(compressed_file_path, "wb") do |file|
+      artifact_url = "https://github.com/#{tester_repository_name}/releases/download/#{latest_tester_version}/#{latest_tester_version}_linux_amd64.tar.gz"
+      puts "Downloading #{artifact_url}"
+
+      HTTParty.get(artifact_url, stream_body: true, follow_redirects: true) do |fragment|
+        file.write(fragment)
+      end
+    end
+
+    FileUtils.mkdir_p(tester_dir)
+    `tar xf #{compressed_file_path} -C #{tester_dir}`
+    unless $?.to_i.eql?(0)
+      puts File.read(compressed_file_path)[0..100]
+      raise "failed to extract archive"
+    end
+
+    File.delete(compressed_file_path)
+
+    tester_dir
+  end
+
+  def latest_tester_version
+    @latest_tester_version ||= begin
+      latest_release = if ENV["GITHUB_TOKEN"].nil?
+        HTTParty.get("https://api.github.com/repos/#{tester_repository_name}/releases/latest")
+      else
+        HTTParty.get("https://api.github.com/repos/#{tester_repository_name}/releases/latest", headers: {"Authorization" => "Bearer #{ENV["GITHUB_TOKEN"]}"})
+      end
+
+      latest_release["tag_name"]
+    end
+  end
+
+  def tester_dir
+    File.join(@testers_root_dir, @course.slug)
+  end
+
+  def tester_repository_name
+    "codecrafters-io/#{@course.slug}-tester"
+  end
+end
diff --git a/test-runner/tests/run_tests_test.rb b/test-runner/tests/run_tests_test.rb
new file mode 100644
index 0000000..49d2473
--- /dev/null
+++ b/test-runner/tests/run_tests_test.rb
@@ -0,0 +1,198 @@
+require_relative "test_helper"
+
+class RunTestsTest < Minitest::Test
+  def setup
+    DatabaseHelper.clean
+
+    @repository = nil
+    @git_repository = nil
+    @test_run = nil
+
+    @fake_server_thread ||= Thread.new do
+      FakeServer.run!
+    end
+  end
+
+  def test_complains_when_test_runner_id_is_invalid
+    create_and_push_git_repository!("redis-ruby")
+
+    error = assert_raises(RuntimeError) do
+      @repository.test_runner.id = "inexistent-test-runner-id"
+
+      RunTestsCommandRunner
+        .new(git_repository: @git_repository, repository: @repository)
+        .run
+    end
+
+    assert_match "test runner not found", error.message
+    assert_equal 0, TestRunResult.count
+  end
+
+  def test_works_when_no_test_runs_are_found
+    create_and_push_git_repository!("redis-ruby")
+    script_result = run_script!
+
+    assert_match "\"should_retry\":false", script_result.stdout
+    assert_equal 0, TestRunResult.count
+
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_test_runs_are_found
+    create_and_push_git_repository!("redis-ruby")
+    create_test_run!
+
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_multiple_test_runs_are_present
+    create_and_push_git_repository!("redis-ruby")
+    test_run_1 = create_test_run!
+    test_run_2 = create_test_run!
+
+    run_script!
+
+    assert_equal 1, test_run_1.results.count
+    assert_equal "success", test_run_1.results.first.status, test_run_1.results.first.parsed_logs
+    assert_equal 1, test_run_2.results.count
+    assert_equal "success", test_run_2.results.first.status, test_run_2.results.first.parsed_logs
+
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_codecrafters_yml_is_missing
+    create_and_push_git_repository!("redis-ruby")
+
+    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
+      FileUtils.rm("#{working_dir}/codecrafters.yml")
+    end
+
+    create_test_run!(commit_sha: commit_sha)
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
+
+    assert_match "Didn't find a codecrafters.yml file", @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_buildpack_has_changed
+    create_and_push_git_repository!("redis-ruby")
+
+    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
+      codecrafters_yml_path = "#{working_dir}/codecrafters.yml"
+      File.write(codecrafters_yml_path, File.read(codecrafters_yml_path).gsub(/ruby-3.3/, "ruby-3.5"))
+    end
+
+    create_test_run!(commit_sha: commit_sha)
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
+
+    assert_match "Detected changes to buildpack (old: ruby-3.3, new: ruby-3.5)", @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_precompilation_fails
+    create_and_push_git_repository!("redis-rust")
+
+    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
+      `echo "abcd" > #{working_dir}/src/main.rs`
+    end
+
+    create_test_run!(commit_sha: commit_sha)
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
+
+    assert_match "code failed to compile", @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def test_works_when_precompilation_succeeds
+    create_and_push_git_repository!("redis-rust")
+
+    create_test_run!
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+
+    assert_match "[compile]", @test_run.results.first.parsed_logs
+  end
+
+  def test_detects_dependency_file_changes
+    create_and_push_git_repository!("redis-rust")
+
+    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
+      `echo "" > #{working_dir}/Cargo.toml`
+    end
+
+    create_test_run!(commit_sha: commit_sha)
+    result = run_script!
+
+    assert_equal 0, @test_run.results.count
+    assert_match "Detected changes to Cargo.toml", result.out
+    assert_equal "starting", @repository.test_runner.reload.machine_status
+  end
+
+  def test_moves_app_cached
+    create_and_push_git_repository!("sqlite-python")
+
+    create_test_run!
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+
+    # If /app-cached is not moved, the following line will be present in the logs
+    refute_match "Creating a virtualenv", @test_run.results.first.parsed_logs
+  end
+
+  def test_works_when_run_sh_is_not_present
+    create_and_push_git_repository!("redis-ruby")
+
+    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
+      FileUtils.mkdir_p("#{working_dir}/.codecrafters")
+      FileUtils.cp("#{working_dir}/.codecrafters/run.sh", "#{working_dir}/spawn_redis_server.sh")
+      FileUtils.rm("#{working_dir}/.codecrafters/run.sh")
+    end
+
+    create_test_run!(commit_sha: commit_sha)
+    run_script!
+
+    assert_equal 1, @test_run.results.count
+    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
+    assert_equal "stopped", @repository.test_runner.reload.machine_status
+  end
+
+  def create_test_run!(commit_sha: nil)
+    commit_sha ||= @git_repository.head_commit_sha
+    @test_run = TestRun.create!(repository_id: @repository.id, id: SecureRandom.uuid, commit_sha: commit_sha)
+  end
+
+  def create_and_push_git_repository!(code_fixture_key)
+    @code_fixture = CodeFixtures.get(code_fixture_key)
+    buildpack = Buildpack.upsert_from_code_fixture!(@code_fixture)
+    @repository = Repository.create!(id: SecureRandom.uuid, course_slug: @code_fixture.fetch("course_slug"), language_slug: @code_fixture.fetch("language_slug"), buildpack: buildpack)
+    @git_repository = FakeGitRepository.new(@code_fixture.fetch("code_dir"), @repository)
+    @git_repository.push_to_git_daemon!
+  end
+
+  def run_script!
+    @git_repository.set_remote_url(@repository.clone_url)
+
+    RunTestsCommandRunner
+      .new(git_repository: @git_repository, repository: @repository)
+      .run
+  end
+end
diff --git a/test-runner/tests/sample_data/docker_logs.txt b/test-runner/tests/sample_data/docker_logs.txt
new file mode 100644
index 0000000..9615c65
--- /dev/null
+++ b/test-runner/tests/sample_data/docker_logs.txt
@@ -0,0 +1,155 @@
+#14 [ 7/21] RUN cargo build --release --target-dir=/tmp/codecrafters-redis-target
+#14 0.600     Updating crates.io index
+#14 0.678  Downloading crates ...
+#14 0.714   Downloaded tokio-macros v1.8.2
+#14 0.717   Downloaded thiserror-impl v1.0.32
+#14 0.719   Downloaded lock_api v0.4.9
+#14 0.720   Downloaded socket2 v0.4.7
+#14 0.722   Downloaded smallvec v1.10.0
+#14 0.724   Downloaded signal-hook-registry v1.2.2
+#14 0.725   Downloaded pin-project-lite v0.2.9
+#14 0.729   Downloaded quote v1.0.7
+#14 0.731   Downloaded memchr v2.3.4
+#14 0.733   Downloaded unicode-xid v0.2.1
+#14 0.734   Downloaded mio v0.8.5
+#14 0.739   Downloaded bytes v1.3.0
+#14 0.742   Downloaded proc-macro2 v1.0.24
+#14 0.744   Downloaded num_cpus v1.13.0
+#14 0.746   Downloaded syn v1.0.67
+#14 0.755   Downloaded log v0.4.11
+#14 0.757   Downloaded tokio v1.23.0
+#14 0.786   Downloaded libc v0.2.138
+#14 0.809   Downloaded parking_lot v0.12.1
+#14 0.810   Downloaded cfg-if v1.0.0
+#14 0.811   Downloaded autocfg v1.1.0
+#14 0.812   Downloaded anyhow v1.0.59
+#14 0.815   Downloaded cfg-if v0.1.10
+#14 0.816   Downloaded thiserror v1.0.32
+#14 0.819   Downloaded parking_lot_core v0.9.5
+#14 0.821   Downloaded scopeguard v1.1.0
+#14 0.864    Compiling libc v0.2.138
+#14 0.864    Compiling proc-macro2 v1.0.24
+#14 0.864    Compiling unicode-xid v0.2.1
+#14 0.864    Compiling autocfg v1.1.0
+#14 0.864    Compiling syn v1.0.67
+#14 0.864    Compiling parking_lot_core v0.9.5
+#14 0.866    Compiling log v0.4.11
+#14 0.866    Compiling scopeguard v1.1.0
+#14 0.867    Compiling cfg-if v1.0.0
+#14 0.868    Compiling cfg-if v0.1.10
+#14 0.868    Compiling smallvec v1.10.0
+#14 0.869    Compiling memchr v2.3.4
+#14 0.870    Compiling anyhow v1.0.59
+#14 0.871    Compiling bytes v1.3.0
+#14 0.872    Compiling pin-project-lite v0.2.9
+#14 1.265    Compiling lock_api v0.4.9
+#14 1.265    Compiling tokio v1.23.0
+#14 1.744    Compiling quote v1.0.7
+#14 1.854    Compiling num_cpus v1.13.0
+#14 1.854    Compiling signal-hook-registry v1.2.2
+#14 1.854    Compiling socket2 v0.4.7
+#14 1.854    Compiling mio v0.8.5
+#14 2.015    Compiling parking_lot v0.12.1
+#14 3.769    Compiling tokio-macros v1.8.2
+#14 3.769    Compiling thiserror-impl v1.0.32
+#14 4.469    Compiling thiserror v1.0.32
+#14 8.128    Compiling redis-starter-rust v0.1.0 (/app)
+#14 8.272     Finished release [optimized] target(s) in 8.01s
+#14 DONE 8.3s
+
+#15 [ 8/21] RUN rm /tmp/codecrafters-redis-target/release/redis-starter-rust
+#15 DONE 0.2s
+
+#16 [ 9/21] RUN rm /tmp/codecrafters-redis-target/release/redis-starter-rust.d
+#16 DONE 0.1s
+
+#17 [10/21] RUN find /tmp/codecrafters-redis-target/release -type f -maxdepth 1 -delete
+#17 DONE 0.2s
+
+#18 [11/21] RUN rm -f /tmp/codecrafters-redis-target/release/deps/*redis_starter_rust*
+#18 DONE 0.2s
+
+#19 [12/21] RUN rm -f /tmp/codecrafters-redis-target/release/deps/redis_starter_rust*
+#19 DONE 0.3s
+
+#20 [13/21] RUN rm -f /tmp/codecrafters-redis-target/release/.fingerprint/*redis_starter_rust*
+#20 DONE 0.2s
+
+#21 [14/21] RUN rm -f /tmp/codecrafters-redis-target/release/.fingerprint/redis_starter_rust*
+#21 DONE 0.2s
+
+#22 [15/21] RUN rm -rf /app/src
+#22 DONE 0.2s
+
+#23 [16/21] RUN echo "cd ${CODECRAFTERS_SUBMISSION_DIR} && cargo build --release --target-dir=/tmp/codecrafters-redis-target --manifest-path Cargo.toml" > /codecrafters-precompile.sh
+#23 DONE 0.2s
+
+#24 [17/21] RUN chmod +x /codecrafters-precompile.sh
+#24 DONE 0.3s
+
+#25 [18/21] RUN apt-get update && apt-get install -y git curl
+#25 0.260 Get:1 http://deb.debian.org/debian buster InRelease [122 kB]
+#25 0.271 Get:2 http://deb.debian.org/debian-security buster/updates InRelease [34.8 kB]
+#25 0.274 Get:3 http://deb.debian.org/debian buster-updates InRelease [56.6 kB]
+#25 0.379 Get:4 http://deb.debian.org/debian buster/main amd64 Packages [7909 kB]
+#25 0.443 Get:5 http://deb.debian.org/debian-security buster/updates/main amd64 Packages [550 kB]
+#25 0.510 Get:6 http://deb.debian.org/debian buster-updates/main amd64 Packages [8788 B]
+#25 1.358 Fetched 8681 kB in 1s (7921 kB/s)
+#25 1.358 Reading package lists...
+#25 1.794 Reading package lists...
+#25 2.213 Building dependency tree...
+#25 2.280 Reading state information...
+#25 2.353 git is already the newest version (1:2.20.1-2+deb10u8).
+#25 2.353 The following additional packages will be installed:
+#25 2.353   libcurl4 libcurl4-openssl-dev
+#25 2.354 Suggested packages:
+#25 2.354   libcurl4-doc libidn11-dev libldap2-dev librtmp-dev libssh2-1-dev
+#25 2.365 The following packages will be upgraded:
+#25 2.365   curl libcurl4 libcurl4-openssl-dev
+#25 2.392 3 upgraded, 0 newly installed, 0 to remove and 42 not upgraded.
+#25 2.392 Need to get 1024 kB of archives.
+#25 2.392 After this operation, 1024 B disk space will be freed.
+#25 2.392 Get:1 http://deb.debian.org/debian-security buster/updates/main amd64 libcurl4-openssl-dev amd64 7.64.0-4+deb10u7 [423 kB]
+#25 2.399 Get:2 http://deb.debian.org/debian-security buster/updates/main amd64 curl amd64 7.64.0-4+deb10u7 [266 kB]
+#25 2.401 Get:3 http://deb.debian.org/debian-security buster/updates/main amd64 libcurl4 amd64 7.64.0-4+deb10u7 [335 kB]
+#25 2.580 debconf: delaying package configuration, since apt-utils is not installed
+#25 2.603 Fetched 1024 kB in 0s (32.7 MB/s)
+#25 2.635 (Reading database ...
+(Reading database ... 5%
+(Reading database ... 10%
+(Reading database ... 15%
+(Reading database ... 20%
+(Reading database ... 25%
+(Reading database ... 30%
+(Reading database ... 35%
+(Reading database ... 40%
+(Reading database ... 45%
+(Reading database ... 50%
+(Reading database ... 55%
+(Reading database ... 60%
+(Reading database ... 65%
+(Reading database ... 70%
+(Reading database ... 75%
+(Reading database ... 80%
+(Reading database ... 85%
+(Reading database ... 90%
+(Reading database ... 95%
+(Reading database ... 100%
+(Reading database ... 23989 files and directories currently installed.)
+#25 2.805 Preparing to unpack .../libcurl4-openssl-dev_7.64.0-4+deb10u7_amd64.deb ...
+#25 2.821 Unpacking libcurl4-openssl-dev:amd64 (7.64.0-4+deb10u7) over (7.64.0-4+deb10u6) ...
+#25 2.964 Preparing to unpack .../curl_7.64.0-4+deb10u7_amd64.deb ...
+#25 2.977 Unpacking curl (7.64.0-4+deb10u7) over (7.64.0-4+deb10u6) ...
+#25 3.052 Preparing to unpack .../libcurl4_7.64.0-4+deb10u7_amd64.deb ...
+#25 3.072 Unpacking libcurl4:amd64 (7.64.0-4+deb10u7) over (7.64.0-4+deb10u6) ...
+#25 3.150 Setting up libcurl4:amd64 (7.64.0-4+deb10u7) ...
+#25 3.163 Setting up curl (7.64.0-4+deb10u7) ...
+#25 3.175 Setting up libcurl4-openssl-dev:amd64 (7.64.0-4+deb10u7) ...
+#25 3.188 Processing triggers for libc-bin (2.28-10+deb10u2) ...
+#25 DONE 3.5s
+
+#26 [19/21] WORKDIR /app
+#26 DONE 0.0s
+
+#27 [20/21] ADD . /app
+#27 DONE 0.1s
\ No newline at end of file
diff --git a/test-runner/tests/test_helper.rb b/test-runner/tests/test_helper.rb
new file mode 100644
index 0000000..01462b4
--- /dev/null
+++ b/test-runner/tests/test_helper.rb
@@ -0,0 +1,25 @@
+require "bundler/setup"
+Bundler.require(:default, :test)
+
+require "zeitwerk"
+loader = Zeitwerk::Loader.new
+loader.push_dir("#{__dir__}/lib")
+loader.push_dir("#{__dir__}/lib/db/models")
+loader.setup
+
+require "dotenv/load"
+
+require "active_record"
+
+require "fileutils"
+require "minitest/autorun"
+require "securerandom"
+
+ActiveRecord::Base.establish_connection(
+  adapter: "sqlite3",
+  database: "/tmp/test.db"
+)
+
+require_relative "lib/db/schema"
+
+ENV["TEST_RUNNER_REPOSITORY_ROOT"] = File.expand_path("../", __dir__)

From 2d1bb3da043692ba62247c31b05d7d74ed6e53ba Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 19:10:34 -0800
Subject: [PATCH 02/13] Refactor GitHub Actions workflows and remove unused
 files from test-runner.

---
 .../.github => .github}/workflows/test.yml    |   4 +
 test-runner/.github/workflows/publish.yml     |  35 ----
 test-runner/.github/workflows/tag.yml         |  29 ---
 test-runner/Makefile                          |   5 +-
 test-runner/README.md                         |  14 +-
 .../backend/create_test_run_result.go         |  41 ----
 .../internal/backend/report_shutdown.go       |  37 ----
 .../internal/backend/reserve_test_run.go      |  62 ------
 .../backend/trigger_infrastructure_rebuild.go |  49 -----
 .../move_app_cached_files_if_needed.go        |  24 ---
 .../internal/run_precompilation_if_needed.go  |  71 -------
 test-runner/internal/run_tester.go            |  33 ---
 test-runner/internal/test_run.go              |  78 -------
 .../tests/lib/run_tests_command_runner.rb     |  53 -----
 test-runner/tests/run_tests_test.rb           | 198 ------------------
 15 files changed, 9 insertions(+), 724 deletions(-)
 rename {test-runner/.github => .github}/workflows/test.yml (91%)
 delete mode 100644 test-runner/.github/workflows/publish.yml
 delete mode 100644 test-runner/.github/workflows/tag.yml
 delete mode 100644 test-runner/internal/backend/create_test_run_result.go
 delete mode 100644 test-runner/internal/backend/report_shutdown.go
 delete mode 100644 test-runner/internal/backend/reserve_test_run.go
 delete mode 100644 test-runner/internal/backend/trigger_infrastructure_rebuild.go
 delete mode 100644 test-runner/internal/move_app_cached_files_if_needed.go
 delete mode 100644 test-runner/internal/run_precompilation_if_needed.go
 delete mode 100644 test-runner/internal/run_tester.go
 delete mode 100644 test-runner/internal/test_run.go
 delete mode 100644 test-runner/tests/lib/run_tests_command_runner.rb
 delete mode 100644 test-runner/tests/run_tests_test.rb

diff --git a/test-runner/.github/workflows/test.yml b/.github/workflows/test.yml
similarity index 91%
rename from test-runner/.github/workflows/test.yml
rename to .github/workflows/test.yml
index 76d4e58..5f97d74 100644
--- a/test-runner/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,9 +37,11 @@ jobs:
           ruby-version: 3.3.5
           bundler-cache: true
           cache-version: 5
+          working-directory: test-runner
 
       - name: Run make refresh_test_fixtures
         run: make refresh_test_fixtures
+        working-directory: test-runner
 
       # Required for pulling git-api and git-daemon
       - name: Authenticate with ghcr.io
@@ -51,6 +53,7 @@ jobs:
 
       - name: Set up Docker
         run: docker compose up -d
+        working-directory: test-runner
 
       - name: Set up Git
         run: |
@@ -59,6 +62,7 @@ jobs:
 
       - name: Run tests
         run: make test
+        working-directory: test-runner
         env:
           DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
           DEPOT_PROJECT: ${{ secrets.DEPOT_PROJECT }}
diff --git a/test-runner/.github/workflows/publish.yml b/test-runner/.github/workflows/publish.yml
deleted file mode 100644
index 9285566..0000000
--- a/test-runner/.github/workflows/publish.yml
+++ /dev/null
@@ -1,35 +0,0 @@
-name: Publish
-
-on:
-  push:
-    tags:
-      - "v*"
-
-permissions:
-  contents: write
-
-jobs:
-  publish_tester:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-
-      - name: Unshallow
-        run: git fetch --prune --unshallow
-
-      - name: Set up Go
-        uses: actions/setup-go@v1
-        with:
-          go-version: 1.21.x
-
-      # Is this needed?
-      # - run: "sudo apt-get install gcc-multilib g++-multilib"
-
-      - name: Run GoReleaser
-        uses: goreleaser/goreleaser-action@v5
-        with:
-          version: v1.21.2
-          args: release -f main.goreleaser.yml --clean
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/test-runner/.github/workflows/tag.yml b/test-runner/.github/workflows/tag.yml
deleted file mode 100644
index 91d6a47..0000000
--- a/test-runner/.github/workflows/tag.yml
+++ /dev/null
@@ -1,29 +0,0 @@
-name: Tag
-
-on:
-  push:
-    branches: [main]
-
-jobs:
-  create-tag:
-    runs-on: ubuntu-latest
-    timeout-minutes: 10
-
-    steps:
-      - uses: actions/checkout@v2
-        with:
-          fetch-depth: 0 # Ensure that all tags are available
-
-      - name: "Compute next version tag"
-        run: |-
-          nextVersionTag=$(make print_next_version_tag)
-          echo "next: $nextVersionTag"
-          echo "::set-output name=next_version_tag::$nextVersionTag"
-        id: compute_next_version_tag
-
-      - name: Bump version and push tag
-        uses: mathieudutour/github-tag-action@v6.2
-        with:
-          github_token: ${{ secrets.CODECRAFTERS_BOT_GITHUB_TOKEN }}
-          custom_tag: ${{ steps.compute_next_version_tag.outputs.next_version_tag }}
-          tag_prefix: ""
diff --git a/test-runner/Makefile b/test-runner/Makefile
index fa58118..7b26481 100644
--- a/test-runner/Makefile
+++ b/test-runner/Makefile
@@ -51,15 +51,12 @@ refresh_test_fixtures:
 	cp -R /tmp/byo-sqlite/solutions/python/01-dr6/code ./tests/fixtures/sqlite-python-pass-stage-1
 	cp /tmp/byo-sqlite/dockerfiles/python-3.13.Dockerfile ./tests/fixtures/dockerfiles/sqlite-python-3.13.Dockerfile
 
-test: test_go test_run_tests test_build_image
+test: test_go test_build_image
 
 test_go:
 	# -mod=mod is required to ensure that go isn't confused by Ruby's vendor/bundle directory
 	go test -mod=mod ./...
 
-test_run_tests: build
-	bundle exec ruby tests/run_tests_test.rb --verbose --fail-fast
-
 test_build_image: build
 	bundle exec ruby tests/build_image_test.rb --verbose --fail-fast
 
diff --git a/test-runner/README.md b/test-runner/README.md
index f5eb571..9af4208 100644
--- a/test-runner/README.md
+++ b/test-runner/README.md
@@ -1,17 +1,11 @@
 # Test Runner
 
-This is the component responsible for running tests for CodeCrafters challenges.
+This is the Go code invoked from the [test-runner-builder](https://github.com/codecrafters-io/test-runner-builder) Docker image.
 
-### Functionality
+Responsibilities:
 
-It supports two commands:
-
-- `build_image`
-  - Builds the docker image that needs to executed to run tests for a challenge
-  - Also streams logs back to a logstream URL
-- `run_tests`
-  - Runs the tests for a challenge (this is the entrypoint of the docker image)
-  - Streams logs back to a logstream URL
+- Builds the docker image that needs to executed to run tests for a challenge
+- Also streams logs back to a logstream URL
 
 ### Testing Locally
 
diff --git a/test-runner/internal/backend/create_test_run_result.go b/test-runner/internal/backend/create_test_run_result.go
deleted file mode 100644
index be51ce6..0000000
--- a/test-runner/internal/backend/create_test_run_result.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package backend
-
-import (
-	"encoding/base64"
-	"encoding/json"
-	"fmt"
-	"io"
-)
-
-func CreateTestRunResult(testRunId string, testRunnerId string, logs []byte, status string) error {
-	body := map[string]string{
-		"test_run_id":    testRunId,
-		"test_runner_id": testRunnerId,
-		"status":         status,
-		"logs_base64":    base64.StdEncoding.EncodeToString(logs),
-	}
-
-	bodyJson, err := json.Marshal(body)
-	if err != nil {
-		return fmt.Errorf("failed to marshal JSON: %w", err)
-	}
-
-	resp, err := PerformRequest("POST", "/services/test_runner/create_test_run_result", bodyJson)
-	if err != nil {
-		return fmt.Errorf("HTTP request failed: %w", err)
-	}
-	defer resp.Body.Close()
-
-	fmt.Printf("Response: %d\n", resp.StatusCode)
-
-	bodyBytes, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return fmt.Errorf("failed to read response body: %w", err)
-	}
-
-	if resp.StatusCode != 200 {
-		return fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
-	}
-
-	return nil
-}
diff --git a/test-runner/internal/backend/report_shutdown.go b/test-runner/internal/backend/report_shutdown.go
deleted file mode 100644
index a4f8942..0000000
--- a/test-runner/internal/backend/report_shutdown.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package backend
-
-import (
-	"encoding/json"
-	"fmt"
-	"io"
-)
-
-func ReportShutdown(testRunnerId string) error {
-	body := map[string]string{
-		"test_runner_id": testRunnerId,
-	}
-
-	bodyJson, err := json.Marshal(body)
-	if err != nil {
-		return fmt.Errorf("failed to marshal JSON: %w", err)
-	}
-
-	resp, err := PerformRequest("POST", "/services/test_runner/report_shutdown", bodyJson)
-	if err != nil {
-		return fmt.Errorf("HTTP request failed: %w", err)
-	}
-	defer resp.Body.Close()
-
-	fmt.Printf("Response: %d\n", resp.StatusCode)
-
-	bodyBytes, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return fmt.Errorf("failed to read response body: %w", err)
-	}
-
-	if resp.StatusCode == 200 {
-		return nil
-	} else {
-		return fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
-	}
-}
diff --git a/test-runner/internal/backend/reserve_test_run.go b/test-runner/internal/backend/reserve_test_run.go
deleted file mode 100644
index a87f75d..0000000
--- a/test-runner/internal/backend/reserve_test_run.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package backend
-
-import (
-	"encoding/json"
-	"fmt"
-	"io"
-)
-
-type HTTPStatusError struct {
-	StatusCode int
-}
-
-func (e *HTTPStatusError) Error() string {
-	return fmt.Sprintf("HTTP status %d", e.StatusCode)
-}
-
-type ReservedTestRun struct {
-	ID            string `json:"id"`
-	CommitSHA     string `json:"commit_sha"`
-	TestCasesJSON string `json:"test_cases_json"`
-	LogstreamURL  string `json:"logstream_url"`
-}
-
-type ReserveTestRunResponse struct {
-	TestRun     *ReservedTestRun `json:"test_run"`
-	ShouldRetry bool             `json:"should_retry"`
-}
-
-func ReserveTestRun(testRunnerId string) (ReserveTestRunResponse, error) {
-	path := fmt.Sprintf("/services/test_runner/reserve_test_run?test_runner_id=%s", testRunnerId)
-
-	resp, err := PerformRequest("POST", path, nil)
-	if err != nil {
-		return ReserveTestRunResponse{}, fmt.Errorf("HTTP request failed: %w", err)
-	}
-
-	defer resp.Body.Close()
-
-	body, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return ReserveTestRunResponse{}, fmt.Errorf("read response failed: %w", err)
-	}
-
-	fmt.Printf("Response (%d): %s\n", resp.StatusCode, string(body))
-
-	// Handle legacy response (TODO: Remove this once we've migrated all clients)
-	if resp.StatusCode == 202 {
-		return ReserveTestRunResponse{ShouldRetry: false}, nil
-	}
-
-	if resp.StatusCode == 200 {
-		var reserveTestRunResponse ReserveTestRunResponse
-
-		if err = json.Unmarshal(body, &reserveTestRunResponse); err != nil {
-			return ReserveTestRunResponse{}, fmt.Errorf("unable to parse response: %w", err)
-		}
-
-		return reserveTestRunResponse, nil
-	} else {
-		return ReserveTestRunResponse{}, &HTTPStatusError{StatusCode: resp.StatusCode}
-	}
-}
diff --git a/test-runner/internal/backend/trigger_infrastructure_rebuild.go b/test-runner/internal/backend/trigger_infrastructure_rebuild.go
deleted file mode 100644
index 54fdac9..0000000
--- a/test-runner/internal/backend/trigger_infrastructure_rebuild.go
+++ /dev/null
@@ -1,49 +0,0 @@
-package backend
-
-import (
-	"encoding/json"
-	"fmt"
-	"io"
-)
-
-type TriggerInfrastructureRebuildResponse struct {
-	ID           string `json:"id"`
-	CommitSHA    string `json:"commit_sha"`
-	LogstreamURL string `json:"logstream_url"`
-}
-
-func TriggerInfrastructureRebuild(testRunId string, testRunnerId string) (TriggerInfrastructureRebuildResponse, error) {
-	body := map[string]string{
-		"test_run_id":    testRunId,
-		"test_runner_id": testRunnerId,
-	}
-
-	bodyJson, err := json.Marshal(body)
-	if err != nil {
-		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to marshal JSON: %w", err)
-	}
-
-	resp, err := PerformRequest("POST", "/services/test_runner/rebuild_for_test_run", bodyJson)
-	if err != nil {
-		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("HTTP request failed: %w", err)
-	}
-
-	defer resp.Body.Close()
-	bodyBytes, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to read response body: %w", err)
-	}
-
-	if resp.StatusCode != 200 {
-		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("unexpected HTTP status %d. Body: %s", resp.StatusCode, string(bodyBytes))
-	}
-
-	buildResponse := &TriggerInfrastructureRebuildResponse{}
-	err = json.Unmarshal(bodyBytes, buildResponse)
-
-	if err != nil {
-		return TriggerInfrastructureRebuildResponse{}, fmt.Errorf("failed to parse response into submission: %w", err)
-	}
-
-	return *buildResponse, nil
-}
diff --git a/test-runner/internal/move_app_cached_files_if_needed.go b/test-runner/internal/move_app_cached_files_if_needed.go
deleted file mode 100644
index 32c85e1..0000000
--- a/test-runner/internal/move_app_cached_files_if_needed.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package internal
-
-import (
-	"fmt"
-	"os"
-
-	cp "github.com/otiai10/copy"
-)
-
-func MoveAppCachedFilesIfNeeded(repositoryDir string) error {
-	if _, err := os.Stat("/app-cached"); !os.IsNotExist(err) {
-		fmt.Printf("Moving /app-cached to %s\n", repositoryDir)
-
-		err := cp.Copy("/app-cached", repositoryDir, cp.Options{
-			PreserveTimes: true, // Some caching strategies rely on file timestamps
-			PreserveOwner: true, // Some caching strategies rely on file ownership
-		})
-		if err != nil {
-			return fmt.Errorf("failed to copy dir: %s", err)
-		}
-	}
-
-	return nil
-}
diff --git a/test-runner/internal/run_precompilation_if_needed.go b/test-runner/internal/run_precompilation_if_needed.go
deleted file mode 100644
index 17921bd..0000000
--- a/test-runner/internal/run_precompilation_if_needed.go
+++ /dev/null
@@ -1,71 +0,0 @@
-package internal
-
-import (
-	"errors"
-	"fmt"
-	"os"
-	"os/exec"
-	"path"
-
-	"github.com/egym-playground/go-prefix-writer/prefixer"
-)
-
-func RunPrecompilationIfNeeded(testRun *TestRun, repositoryDir string) error {
-	logWriter := testRun
-	logWithPrefixWriter := prefixer.New(logWriter, func() string { return "\033[33m[compile]\033[0m " })
-
-	newPrecompileFilePath := path.Join(repositoryDir, ".codecrafters/compile.sh")
-	legacyPrecompileFilePath := "/codecrafters-precompile.sh"
-
-	var precompileFilePath string
-	_, newPrecompileFilePathErr := os.Stat(newPrecompileFilePath)
-	_, legacyPrecompileFilePathErr := os.Stat(legacyPrecompileFilePath)
-
-	if newPrecompileFilePathErr == nil {
-		precompileFilePath = newPrecompileFilePath
-	} else if legacyPrecompileFilePathErr == nil {
-		precompileFilePath = legacyPrecompileFilePath
-	} else if !errors.Is(newPrecompileFilePathErr, os.ErrNotExist) { // new script exists but failed to stat
-		return &FriendlyError{
-			UserError:     "CodeCrafters internal error: failed to stat precompile script: " + newPrecompileFilePathErr.Error(),
-			InternalError: "failed to stat precompile script: " + newPrecompileFilePathErr.Error(),
-		}
-	} else if !errors.Is(legacyPrecompileFilePathErr, os.ErrNotExist) { // legacy script exists but failed to stat
-		return &FriendlyError{
-			UserError:     "CodeCrafters internal error: failed to stat precompile script: " + legacyPrecompileFilePathErr.Error(),
-			InternalError: "failed to stat precompile script: " + legacyPrecompileFilePathErr.Error(),
-		}
-	}
-
-	// No precompile script found
-	if precompileFilePath == "" {
-		return nil
-	}
-
-	cmd := exec.Command("sh", precompileFilePath)
-	cmd.Env = os.Environ()
-	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_SUBMISSION_DIR=%s", repositoryDir)) // TODO: Legacy, remove
-	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_REPOSITORY_DIR=%s", repositoryDir))
-	cmd.Stdout = logWithPrefixWriter
-	cmd.Stderr = logWithPrefixWriter
-
-	err := cmd.Run()
-	if _, ok := err.(*exec.ExitError); ok {
-		logWithPrefixWriter.Write([]byte("\033[31mLooks like your code failed to compile.\033[0m\n"))
-		logWithPrefixWriter.Write([]byte("\033[31mIf you think this is a CodeCrafters error, please let us know at hello@codecrafters.io.\033[0m\n"))
-		logWriter.Write([]byte("\n"))
-
-		return &FriendlyError{
-			UserError:     "Compilation failed (user error!)",
-			InternalError: "Compilation failed (internal error!)",
-			IsLogged:      true,
-		}
-	} else if err != nil {
-		return &FriendlyError{
-			UserError:     "CodeCrafters internal error: failed to run precompile script: " + err.Error(),
-			InternalError: "failed to run precompile script: " + err.Error(),
-		}
-	}
-
-	return nil
-}
diff --git a/test-runner/internal/run_tester.go b/test-runner/internal/run_tester.go
deleted file mode 100644
index bbedf76..0000000
--- a/test-runner/internal/run_tester.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package internal
-
-import (
-	"fmt"
-	"os"
-	"os/exec"
-	"path"
-)
-
-func RunTester(testRun *TestRun, repositoryDir string, testerDir string) (bool, error) {
-	cmd := exec.Command(path.Join(testerDir, "test.sh"))
-	cmd.Env = os.Environ()
-	cmd.Env = append(cmd.Env, "PYTHONUNBUFFERED=true")                                      // TODO: Move this to dockerfile?
-	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_SUBMISSION_DIR=%s", repositoryDir)) // TODO: Legacy, remove
-	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_REPOSITORY_DIR=%s", repositoryDir))
-	cmd.Env = append(cmd.Env, fmt.Sprintf("TESTER_DIR=%s", testerDir))
-	cmd.Env = append(cmd.Env, fmt.Sprintf("CODECRAFTERS_TEST_CASES_JSON=%s", testRun.TestCasesJSON))
-	cmd.Stdout = testRun
-	cmd.Stderr = testRun
-
-	err := cmd.Run()
-	if exitError, ok := err.(*exec.ExitError); ok {
-		if exitError.ExitCode() != 0 && exitError.ExitCode() != 1 {
-			return false, err
-		}
-
-		return exitError.ExitCode() == 0, nil
-	} else if err != nil {
-		return false, err
-	}
-
-	return true, nil
-}
diff --git a/test-runner/internal/test_run.go b/test-runner/internal/test_run.go
deleted file mode 100644
index ad460be..0000000
--- a/test-runner/internal/test_run.go
+++ /dev/null
@@ -1,78 +0,0 @@
-package internal
-
-import (
-	"fmt"
-	"io"
-	"os"
-
-	"github.com/codecrafters-io/logstream/redis"
-)
-
-type TestRun struct {
-	ID            string
-	CommitSHA     string
-	TestCasesJSON string
-	LogstreamURL  string
-
-	logstreamWriter *redis.Producer
-	logsFile        *os.File
-}
-
-func (t *TestRun) InitLogging() error {
-	logstreamWriter, err := redis.NewProducer(t.LogstreamURL)
-	if err != nil {
-		return fmt.Errorf("failed to create logstream writer: %w", err)
-	}
-
-	logsFile, err := os.CreateTemp("", "test-run")
-	if err != nil {
-		return fmt.Errorf("failed to create temporary file: %w", err)
-	}
-
-	t.logstreamWriter = logstreamWriter
-	t.logsFile = logsFile
-
-	return nil
-}
-
-func (t *TestRun) CleanupLogging() {
-	if t.logsFile != nil {
-		err := os.Remove(t.logsFile.Name())
-		if err != nil {
-			fmt.Printf("CodeCrafters Internal Error: unable to delete logs file: %v\n", err)
-		}
-
-		t.logsFile = nil
-	}
-}
-
-func (t *TestRun) ReadLogsFromFile() ([]byte, error) {
-	t.logsFile.Seek(0, 0)
-	logs, err := io.ReadAll(t.logsFile)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read logs from file: %w", err)
-	}
-
-	return logs, nil
-}
-
-func (t *TestRun) Write(p []byte) (n int, err error) {
-	_, logStreamError := t.logstreamWriter.Write(p)
-	_, fileError := t.logsFile.Write(p)
-	_, _ = os.Stdout.Write(p)
-
-	if logStreamError != nil {
-		return 0, fmt.Errorf("failed to write to logstream: %w", logStreamError)
-	}
-
-	if fileError != nil {
-		return 0, fmt.Errorf("failed to write to file: %w", fileError)
-	}
-
-	return len(p), nil
-}
-
-func (t *TestRun) Close() {
-	t.logstreamWriter.Close()
-	t.logsFile.Close()
-}
diff --git a/test-runner/tests/lib/run_tests_command_runner.rb b/test-runner/tests/lib/run_tests_command_runner.rb
deleted file mode 100644
index 88067fa..0000000
--- a/test-runner/tests/lib/run_tests_command_runner.rb
+++ /dev/null
@@ -1,53 +0,0 @@
-TEST_RUNNER_LINUX_EXECUTABLE_PATH = File.expand_path("../../dist/main-linux.out", __dir__)
-TESTERS_DIR = File.expand_path("../fixtures/testers", __dir__)
-
-class RunTestsCommandRunner
-  attr_accessor :git_repository
-  attr_accessor :repository
-
-  def initialize(git_repository:, repository:)
-    self.git_repository = git_repository
-    self.repository = repository
-  end
-
-  def dockerfile_path
-    repository.dockerfile_path(git_repository)
-  end
-
-  def run
-    tmp_dir = Dir.mktmpdir
-    tester_dir = TesterDownloader.new(course: OpenStruct.new(slug: repository.course_slug), testers_root_dir: TESTERS_DIR).download_if_needed
-
-    FileUtils.rm_rf(tmp_dir)
-    FileUtils.cp_r(git_repository.tmp_dir, tmp_dir)
-
-    dockerfile_handle = Tempfile.new
-    dockerfile_handle.write(repository.buildpack.processed_dockerfile_contents)
-    dockerfile_handle.close
-
-    puts File.read(dockerfile_handle.path)
-
-    # Required for build
-    FileUtils.mkdir_p("#{tmp_dir}/test-runner")
-    FileUtils.cp(TEST_RUNNER_LINUX_EXECUTABLE_PATH, "#{tmp_dir}/test-runner/test-runner")
-    FileUtils.cp_r(tester_dir, "#{tmp_dir}/tester")
-
-    result = TTY::Command.new.run("docker build --quiet -t test_runner_test_image -f #{dockerfile_handle.path} #{tmp_dir}")
-    raise "Docker build failed. Stdout: #{result.out}. Stderr: #{result.err}" unless result.status == 0
-
-    command_parts = [
-      "docker run",
-      "-e CODECRAFTERS_SERVER_URL=http://host.docker.internal:6331",
-      "-e CODECRAFTERS_TEST_RUNNER_ID=#{repository.test_runner.id}",
-      "-e REPOSITORY_ID=#{repository.id}",
-      "--add-host=host.docker.internal:host-gateway", # Required for CI, works by default on macOS
-      "--rm ",
-      "test_runner_test_image"
-    ]
-
-    result = TTY::Command.new.run(command_parts.join(" "))
-    raise "Test runner script failed. Stdout: #{result.out}. Stderr: #{result.err}" unless result.status == 0
-
-    result
-  end
-end
diff --git a/test-runner/tests/run_tests_test.rb b/test-runner/tests/run_tests_test.rb
deleted file mode 100644
index 49d2473..0000000
--- a/test-runner/tests/run_tests_test.rb
+++ /dev/null
@@ -1,198 +0,0 @@
-require_relative "test_helper"
-
-class RunTestsTest < Minitest::Test
-  def setup
-    DatabaseHelper.clean
-
-    @repository = nil
-    @git_repository = nil
-    @test_run = nil
-
-    @fake_server_thread ||= Thread.new do
-      FakeServer.run!
-    end
-  end
-
-  def test_complains_when_test_runner_id_is_invalid
-    create_and_push_git_repository!("redis-ruby")
-
-    error = assert_raises(RuntimeError) do
-      @repository.test_runner.id = "inexistent-test-runner-id"
-
-      RunTestsCommandRunner
-        .new(git_repository: @git_repository, repository: @repository)
-        .run
-    end
-
-    assert_match "test runner not found", error.message
-    assert_equal 0, TestRunResult.count
-  end
-
-  def test_works_when_no_test_runs_are_found
-    create_and_push_git_repository!("redis-ruby")
-    script_result = run_script!
-
-    assert_match "\"should_retry\":false", script_result.stdout
-    assert_equal 0, TestRunResult.count
-
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_test_runs_are_found
-    create_and_push_git_repository!("redis-ruby")
-    create_test_run!
-
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_multiple_test_runs_are_present
-    create_and_push_git_repository!("redis-ruby")
-    test_run_1 = create_test_run!
-    test_run_2 = create_test_run!
-
-    run_script!
-
-    assert_equal 1, test_run_1.results.count
-    assert_equal "success", test_run_1.results.first.status, test_run_1.results.first.parsed_logs
-    assert_equal 1, test_run_2.results.count
-    assert_equal "success", test_run_2.results.first.status, test_run_2.results.first.parsed_logs
-
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_codecrafters_yml_is_missing
-    create_and_push_git_repository!("redis-ruby")
-
-    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
-      FileUtils.rm("#{working_dir}/codecrafters.yml")
-    end
-
-    create_test_run!(commit_sha: commit_sha)
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
-
-    assert_match "Didn't find a codecrafters.yml file", @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_buildpack_has_changed
-    create_and_push_git_repository!("redis-ruby")
-
-    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
-      codecrafters_yml_path = "#{working_dir}/codecrafters.yml"
-      File.write(codecrafters_yml_path, File.read(codecrafters_yml_path).gsub(/ruby-3.3/, "ruby-3.5"))
-    end
-
-    create_test_run!(commit_sha: commit_sha)
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
-
-    assert_match "Detected changes to buildpack (old: ruby-3.3, new: ruby-3.5)", @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_precompilation_fails
-    create_and_push_git_repository!("redis-rust")
-
-    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
-      `echo "abcd" > #{working_dir}/src/main.rs`
-    end
-
-    create_test_run!(commit_sha: commit_sha)
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "failure", @test_run.results.first.status, @test_run.results.first.parsed_logs
-
-    assert_match "code failed to compile", @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def test_works_when_precompilation_succeeds
-    create_and_push_git_repository!("redis-rust")
-
-    create_test_run!
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-
-    assert_match "[compile]", @test_run.results.first.parsed_logs
-  end
-
-  def test_detects_dependency_file_changes
-    create_and_push_git_repository!("redis-rust")
-
-    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
-      `echo "" > #{working_dir}/Cargo.toml`
-    end
-
-    create_test_run!(commit_sha: commit_sha)
-    result = run_script!
-
-    assert_equal 0, @test_run.results.count
-    assert_match "Detected changes to Cargo.toml", result.out
-    assert_equal "starting", @repository.test_runner.reload.machine_status
-  end
-
-  def test_moves_app_cached
-    create_and_push_git_repository!("sqlite-python")
-
-    create_test_run!
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-
-    # If /app-cached is not moved, the following line will be present in the logs
-    refute_match "Creating a virtualenv", @test_run.results.first.parsed_logs
-  end
-
-  def test_works_when_run_sh_is_not_present
-    create_and_push_git_repository!("redis-ruby")
-
-    commit_sha = @git_repository.commit_changes_to_branch! do |working_dir|
-      FileUtils.mkdir_p("#{working_dir}/.codecrafters")
-      FileUtils.cp("#{working_dir}/.codecrafters/run.sh", "#{working_dir}/spawn_redis_server.sh")
-      FileUtils.rm("#{working_dir}/.codecrafters/run.sh")
-    end
-
-    create_test_run!(commit_sha: commit_sha)
-    run_script!
-
-    assert_equal 1, @test_run.results.count
-    assert_equal "success", @test_run.results.first.status, @test_run.results.first.parsed_logs
-    assert_equal "stopped", @repository.test_runner.reload.machine_status
-  end
-
-  def create_test_run!(commit_sha: nil)
-    commit_sha ||= @git_repository.head_commit_sha
-    @test_run = TestRun.create!(repository_id: @repository.id, id: SecureRandom.uuid, commit_sha: commit_sha)
-  end
-
-  def create_and_push_git_repository!(code_fixture_key)
-    @code_fixture = CodeFixtures.get(code_fixture_key)
-    buildpack = Buildpack.upsert_from_code_fixture!(@code_fixture)
-    @repository = Repository.create!(id: SecureRandom.uuid, course_slug: @code_fixture.fetch("course_slug"), language_slug: @code_fixture.fetch("language_slug"), buildpack: buildpack)
-    @git_repository = FakeGitRepository.new(@code_fixture.fetch("code_dir"), @repository)
-    @git_repository.push_to_git_daemon!
-  end
-
-  def run_script!
-    @git_repository.set_remote_url(@repository.clone_url)
-
-    RunTestsCommandRunner
-      .new(git_repository: @git_repository, repository: @repository)
-      .run
-  end
-end

From a0ecd9c6511c0aa1f69acad7e543f1af17c27ee1 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 19:18:16 -0800
Subject: [PATCH 03/13] Add Go installation and test runner build to
 Dockerfile; update main.go for version check.

---
 Dockerfile          | 19 ++++++++++++++++---
 test-runner/main.go |  7 +++++++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index e8a21ac..52faf72 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,6 +3,17 @@ FROM debian:bookworm-slim
 # Install deps
 RUN apt-get update && apt-get install -y curl wget jq tar git docker.io
 
+# Install Go
+RUN wget https://go.dev/dl/go1.25.0.linux-amd64.tar.gz -O /tmp/go.tar.gz && \
+    rm -rf /usr/local/go && \
+    tar -C /usr/local -xzf /tmp/go.tar.gz && \
+    rm /tmp/go.tar.gz
+
+ENV PATH="/usr/local/go/bin:$PATH"
+
+# Ensure Go is installed and working
+RUN go version
+
 # Install depot
 RUN curl -fsSL https://depot.dev/install-cli.sh -o /tmp/install-cli.sh && \
     sh /tmp/install-cli.sh 2.100.12 && \
@@ -14,6 +25,8 @@ ENV PATH="/root/.depot/bin:$PATH"
 # Ensure depot is installed and working
 RUN depot --version
 
-# Download test runner CLI
-COPY download_test_runner.sh /tmp/download_test_runner.sh
-RUN --mount=type=secret,id=test_runner_downloader_token,env=GITHUB_TOKEN /tmp/download_test_runner.sh
\ No newline at end of file
+COPY test-runner/ /tmp/test-runner/
+RUN cd /tmp/test-runner && go build -o /var/opt/test-runner-builder main.go
+
+# Ensure the Go program is installed and working
+RUN /var/opt/test-runner-builder --version
\ No newline at end of file
diff --git a/test-runner/main.go b/test-runner/main.go
index bb02e66..4788055 100644
--- a/test-runner/main.go
+++ b/test-runner/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/codecrafters-io/test-runner/internal/commands"
@@ -12,6 +13,12 @@ func main() {
 	utils.InitSentry()
 	defer utils.TeardownSentry()
 
+	// Used to check if the test runner is installed in the dockerfile
+	if len(os.Args) == 2 && os.Args[1] == "--version" {
+		fmt.Println("Test runner installed!")
+		os.Exit(0)
+	}
+
 	exitCode := 0
 
 	func() {

From 813ecf50974e5b4374eb226dfe1e22d542f149b0 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 19:19:18 -0800
Subject: [PATCH 04/13] update

---
 test-runner/internal/commands/build_image_command.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test-runner/internal/commands/build_image_command.go b/test-runner/internal/commands/build_image_command.go
index 702848d..64a9401 100644
--- a/test-runner/internal/commands/build_image_command.go
+++ b/test-runner/internal/commands/build_image_command.go
@@ -111,7 +111,7 @@ func BuildImageCommand() int {
 	flag.StringVar(&testRunnerDir, "test-runner-dir", "", "The directory of the test runner")
 	flag.StringVar(&testerDir, "tester-dir", "", "The directory of the tester")
 
-	flag.CommandLine.Parse(os.Args[2:]) // Use 2: to avoid the first command
+	flag.CommandLine.Parse(os.Args[1:]) // Use 1: to avoid the first command (the program name)
 
 	if codecraftersServerUrl == "" {
 		fmt.Println("codecrafters-server-url must be provided")

From 41eae83a210046dfccf3a74015468ea619faa75b Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:04:12 -0800
Subject: [PATCH 05/13] update Go version from 1.21 to 1.25 in GitHub Actions
 workflow configuration

---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5f97d74..95b1b87 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -29,7 +29,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: "1.21"
+          go-version: "1.25"
 
       - name: Set up ruby
         uses: ruby/setup-ruby@v1

From cde29bca08fae3a2d90c80bd39c4dc7f12a1db1d Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:16:04 -0800
Subject: [PATCH 06/13] Remove redundant "build_image" command from
 BuildImageCommandRunner.

---
 test-runner/tests/lib/build_image_command_runner.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test-runner/tests/lib/build_image_command_runner.rb b/test-runner/tests/lib/build_image_command_runner.rb
index def1886..42938b6 100644
--- a/test-runner/tests/lib/build_image_command_runner.rb
+++ b/test-runner/tests/lib/build_image_command_runner.rb
@@ -27,7 +27,6 @@ def run(build:, test_run: nil)
 
     command_parts = [
       TEST_RUNNER_EXECUTABLE_PATH,
-      "build_image",
       "--buildpack-slug='#{repository.buildpack.slug}'",
       "--buildpack-dockerfile-path='#{dockerfile_handle.path}'",
       "--build-id='#{build.id}'",

From 1a45c549aacefbc48404ef0d7c9a6c93303ebe44 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:20:15 -0800
Subject: [PATCH 07/13] Update Dockerfile and rename test-runner to builder
 with new download script.

---
 Dockerfile                                    |  7 ++--
 {test-runner => builder}/.env.example         |  0
 {test-runner => builder}/.gitignore           |  0
 {test-runner => builder}/.ruby-version        |  0
 {test-runner => builder}/Gemfile              |  0
 {test-runner => builder}/Gemfile.lock         |  0
 {test-runner => builder}/Makefile             |  0
 {test-runner => builder}/README.md            |  2 +-
 {test-runner => builder}/docker-compose.yml   |  0
 {test-runner => builder}/go.mod               |  2 +-
 {test-runner => builder}/go.sum               |  0
 .../internal/backend/client.go                |  2 +-
 .../internal/backend/finalize_build.go        |  0
 .../internal/build_image.go                   |  2 +-
 .../internal/build_logs_processor.go          |  0
 .../internal/build_logs_processor_test.go     |  0
 .../internal/color/color.go                   |  0
 .../internal/commands/build_image_command.go  |  8 ++---
 .../internal/friendly_error.go                |  0
 .../internal/get_buildpack.go                 |  0
 .../internal/get_head_commit_sha.go           |  0
 .../globals/codecrafters_server_url.go        |  0
 .../internal/switch_to_commit.go              |  0
 .../internal/test_runner_build.go             |  0
 .../internal/utils/sentry.go                  |  0
 {test-runner => builder}/main.go              |  4 +--
 {test-runner => builder}/main.goreleaser.yml  |  0
 .../tests/build_image_test.rb                 |  0
 .../tests/lib/build_image_command_runner.rb   |  0
 .../lib/buildpack_dockerfile_processor.rb     |  0
 .../tests/lib/code_fixtures.rb                |  0
 .../tests/lib/database_helper.rb              |  0
 .../tests/lib/db/models/application_record.rb |  0
 .../tests/lib/db/models/buildpack.rb          |  0
 .../tests/lib/db/models/repository.rb         |  0
 .../tests/lib/db/models/submission.rb         |  0
 .../tests/lib/db/models/test_run.rb           |  0
 .../tests/lib/db/models/test_run_result.rb    |  0
 .../tests/lib/db/models/test_runner.rb        |  0
 .../tests/lib/db/models/test_runner_build.rb  |  0
 .../tests/lib/db/schema.rb                    |  0
 .../tests/lib/fake_git_repository.rb          |  0
 .../tests/lib/fake_server.rb                  |  0
 .../tests/lib/git_api_gateway.rb              |  0
 .../submission_test_runner_actions_builder.rb |  0
 .../await_terminal_build_status.rb            |  0
 .../await_terminal_submission_status.rb       |  0
 .../tests/lib/test_runner_actions/base.rb     |  0
 .../lib/test_runner_actions/print_message.rb  |  0
 .../tests/lib/test_runner_actions/sleep.rb    |  0
 .../lib/test_runner_actions/stream_logs.rb    |  0
 .../lib/test_runner_actions/terminate.rb      |  0
 .../tests/lib/tester_downloader.rb            |  0
 .../tests/sample_data/docker_logs.txt         |  0
 {test-runner => builder}/tests/test_helper.rb |  0
 download_test_runner.sh                       | 36 +++++++++++++++++++
 56 files changed, 51 insertions(+), 12 deletions(-)
 rename {test-runner => builder}/.env.example (100%)
 rename {test-runner => builder}/.gitignore (100%)
 rename {test-runner => builder}/.ruby-version (100%)
 rename {test-runner => builder}/Gemfile (100%)
 rename {test-runner => builder}/Gemfile.lock (100%)
 rename {test-runner => builder}/Makefile (100%)
 rename {test-runner => builder}/README.md (93%)
 rename {test-runner => builder}/docker-compose.yml (100%)
 rename {test-runner => builder}/go.mod (95%)
 rename {test-runner => builder}/go.sum (100%)
 rename {test-runner => builder}/internal/backend/client.go (95%)
 rename {test-runner => builder}/internal/backend/finalize_build.go (100%)
 rename {test-runner => builder}/internal/build_image.go (98%)
 rename {test-runner => builder}/internal/build_logs_processor.go (100%)
 rename {test-runner => builder}/internal/build_logs_processor_test.go (100%)
 rename {test-runner => builder}/internal/color/color.go (100%)
 rename {test-runner => builder}/internal/commands/build_image_command.go (97%)
 rename {test-runner => builder}/internal/friendly_error.go (100%)
 rename {test-runner => builder}/internal/get_buildpack.go (100%)
 rename {test-runner => builder}/internal/get_head_commit_sha.go (100%)
 rename {test-runner => builder}/internal/globals/codecrafters_server_url.go (100%)
 rename {test-runner => builder}/internal/switch_to_commit.go (100%)
 rename {test-runner => builder}/internal/test_runner_build.go (100%)
 rename {test-runner => builder}/internal/utils/sentry.go (100%)
 rename {test-runner => builder}/main.go (78%)
 rename {test-runner => builder}/main.goreleaser.yml (100%)
 rename {test-runner => builder}/tests/build_image_test.rb (100%)
 rename {test-runner => builder}/tests/lib/build_image_command_runner.rb (100%)
 rename {test-runner => builder}/tests/lib/buildpack_dockerfile_processor.rb (100%)
 rename {test-runner => builder}/tests/lib/code_fixtures.rb (100%)
 rename {test-runner => builder}/tests/lib/database_helper.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/application_record.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/buildpack.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/repository.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/submission.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/test_run.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/test_run_result.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/test_runner.rb (100%)
 rename {test-runner => builder}/tests/lib/db/models/test_runner_build.rb (100%)
 rename {test-runner => builder}/tests/lib/db/schema.rb (100%)
 rename {test-runner => builder}/tests/lib/fake_git_repository.rb (100%)
 rename {test-runner => builder}/tests/lib/fake_server.rb (100%)
 rename {test-runner => builder}/tests/lib/git_api_gateway.rb (100%)
 rename {test-runner => builder}/tests/lib/submission_test_runner_actions_builder.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/await_terminal_build_status.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/await_terminal_submission_status.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/base.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/print_message.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/sleep.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/stream_logs.rb (100%)
 rename {test-runner => builder}/tests/lib/test_runner_actions/terminate.rb (100%)
 rename {test-runner => builder}/tests/lib/tester_downloader.rb (100%)
 rename {test-runner => builder}/tests/sample_data/docker_logs.txt (100%)
 rename {test-runner => builder}/tests/test_helper.rb (100%)
 create mode 100755 download_test_runner.sh

diff --git a/Dockerfile b/Dockerfile
index 52faf72..7e65ab1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,8 +25,11 @@ ENV PATH="/root/.depot/bin:$PATH"
 # Ensure depot is installed and working
 RUN depot --version
 
-COPY test-runner/ /tmp/test-runner/
-RUN cd /tmp/test-runner && go build -o /var/opt/test-runner-builder main.go
+COPY builder/ /tmp/builder/
+RUN cd /tmp/builder && go build -o /var/opt/test-runner-builder main.go
+
+COPY download_test_runner.sh /tmp/download_test_runner.sh
+RUN --mount=type=secret,id=test_runner_downloader_token,env=GITHUB_TOKEN /tmp/download_test_runner.sh
 
 # Ensure the Go program is installed and working
 RUN /var/opt/test-runner-builder --version
\ No newline at end of file
diff --git a/test-runner/.env.example b/builder/.env.example
similarity index 100%
rename from test-runner/.env.example
rename to builder/.env.example
diff --git a/test-runner/.gitignore b/builder/.gitignore
similarity index 100%
rename from test-runner/.gitignore
rename to builder/.gitignore
diff --git a/test-runner/.ruby-version b/builder/.ruby-version
similarity index 100%
rename from test-runner/.ruby-version
rename to builder/.ruby-version
diff --git a/test-runner/Gemfile b/builder/Gemfile
similarity index 100%
rename from test-runner/Gemfile
rename to builder/Gemfile
diff --git a/test-runner/Gemfile.lock b/builder/Gemfile.lock
similarity index 100%
rename from test-runner/Gemfile.lock
rename to builder/Gemfile.lock
diff --git a/test-runner/Makefile b/builder/Makefile
similarity index 100%
rename from test-runner/Makefile
rename to builder/Makefile
diff --git a/test-runner/README.md b/builder/README.md
similarity index 93%
rename from test-runner/README.md
rename to builder/README.md
index 9af4208..57251f1 100644
--- a/test-runner/README.md
+++ b/builder/README.md
@@ -30,5 +30,5 @@ To run a specific test:
 - Releases are automatically created on pushes to `main`
   - This happens via [./github/workflows/{tag,release}.yml](.github/workflows/tag.yml)
   - It takes 2-3 minutes for a release to be created after a push to `main`.
-  - You can confirm that a release has been created by checking the [Releases](https://github.com/codecrafters-io/test-runner/releases) page.
+  - You can confirm that a release has been created by checking the [Releases](https://github.com/codecrafters-io/test-runner-builder/releases) page.
 - Ask Paul to deploy the release (this part isn't automated yet)
diff --git a/test-runner/docker-compose.yml b/builder/docker-compose.yml
similarity index 100%
rename from test-runner/docker-compose.yml
rename to builder/docker-compose.yml
diff --git a/test-runner/go.mod b/builder/go.mod
similarity index 95%
rename from test-runner/go.mod
rename to builder/go.mod
index b409f39..63b8312 100644
--- a/test-runner/go.mod
+++ b/builder/go.mod
@@ -1,4 +1,4 @@
-module github.com/codecrafters-io/test-runner
+module github.com/codecrafters-io/test-runner-builder
 
 go 1.23
 
diff --git a/test-runner/go.sum b/builder/go.sum
similarity index 100%
rename from test-runner/go.sum
rename to builder/go.sum
diff --git a/test-runner/internal/backend/client.go b/builder/internal/backend/client.go
similarity index 95%
rename from test-runner/internal/backend/client.go
rename to builder/internal/backend/client.go
index 8461fdb..9f23b88 100644
--- a/test-runner/internal/backend/client.go
+++ b/builder/internal/backend/client.go
@@ -6,7 +6,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/codecrafters-io/test-runner/internal/globals"
+	"github.com/codecrafters-io/test-runner-builder/internal/globals"
 	"github.com/google/uuid"
 	"github.com/hashicorp/go-retryablehttp"
 )
diff --git a/test-runner/internal/backend/finalize_build.go b/builder/internal/backend/finalize_build.go
similarity index 100%
rename from test-runner/internal/backend/finalize_build.go
rename to builder/internal/backend/finalize_build.go
diff --git a/test-runner/internal/build_image.go b/builder/internal/build_image.go
similarity index 98%
rename from test-runner/internal/build_image.go
rename to builder/internal/build_image.go
index 49a9ae5..d29df13 100644
--- a/test-runner/internal/build_image.go
+++ b/builder/internal/build_image.go
@@ -6,7 +6,7 @@ import (
 	"os/exec"
 	"path/filepath"
 
-	"github.com/codecrafters-io/test-runner/internal/globals"
+	"github.com/codecrafters-io/test-runner-builder/internal/globals"
 	"github.com/egym-playground/go-prefix-writer/prefixer"
 	cp "github.com/otiai10/copy"
 	"gvisor.dev/gvisor/pkg/linewriter"
diff --git a/test-runner/internal/build_logs_processor.go b/builder/internal/build_logs_processor.go
similarity index 100%
rename from test-runner/internal/build_logs_processor.go
rename to builder/internal/build_logs_processor.go
diff --git a/test-runner/internal/build_logs_processor_test.go b/builder/internal/build_logs_processor_test.go
similarity index 100%
rename from test-runner/internal/build_logs_processor_test.go
rename to builder/internal/build_logs_processor_test.go
diff --git a/test-runner/internal/color/color.go b/builder/internal/color/color.go
similarity index 100%
rename from test-runner/internal/color/color.go
rename to builder/internal/color/color.go
diff --git a/test-runner/internal/commands/build_image_command.go b/builder/internal/commands/build_image_command.go
similarity index 97%
rename from test-runner/internal/commands/build_image_command.go
rename to builder/internal/commands/build_image_command.go
index 64a9401..5a96276 100644
--- a/test-runner/internal/commands/build_image_command.go
+++ b/builder/internal/commands/build_image_command.go
@@ -7,10 +7,10 @@ import (
 	"path/filepath"
 	"strings"
 
-	"github.com/codecrafters-io/test-runner/internal"
-	"github.com/codecrafters-io/test-runner/internal/backend"
-	"github.com/codecrafters-io/test-runner/internal/color"
-	"github.com/codecrafters-io/test-runner/internal/globals"
+	"github.com/codecrafters-io/test-runner-builder/internal"
+	"github.com/codecrafters-io/test-runner-builder/internal/backend"
+	"github.com/codecrafters-io/test-runner-builder/internal/color"
+	"github.com/codecrafters-io/test-runner-builder/internal/globals"
 )
 
 // If err is FriendlyError, it's a user error. Otherwise, it's an internal error.
diff --git a/test-runner/internal/friendly_error.go b/builder/internal/friendly_error.go
similarity index 100%
rename from test-runner/internal/friendly_error.go
rename to builder/internal/friendly_error.go
diff --git a/test-runner/internal/get_buildpack.go b/builder/internal/get_buildpack.go
similarity index 100%
rename from test-runner/internal/get_buildpack.go
rename to builder/internal/get_buildpack.go
diff --git a/test-runner/internal/get_head_commit_sha.go b/builder/internal/get_head_commit_sha.go
similarity index 100%
rename from test-runner/internal/get_head_commit_sha.go
rename to builder/internal/get_head_commit_sha.go
diff --git a/test-runner/internal/globals/codecrafters_server_url.go b/builder/internal/globals/codecrafters_server_url.go
similarity index 100%
rename from test-runner/internal/globals/codecrafters_server_url.go
rename to builder/internal/globals/codecrafters_server_url.go
diff --git a/test-runner/internal/switch_to_commit.go b/builder/internal/switch_to_commit.go
similarity index 100%
rename from test-runner/internal/switch_to_commit.go
rename to builder/internal/switch_to_commit.go
diff --git a/test-runner/internal/test_runner_build.go b/builder/internal/test_runner_build.go
similarity index 100%
rename from test-runner/internal/test_runner_build.go
rename to builder/internal/test_runner_build.go
diff --git a/test-runner/internal/utils/sentry.go b/builder/internal/utils/sentry.go
similarity index 100%
rename from test-runner/internal/utils/sentry.go
rename to builder/internal/utils/sentry.go
diff --git a/test-runner/main.go b/builder/main.go
similarity index 78%
rename from test-runner/main.go
rename to builder/main.go
index 4788055..6e9daee 100644
--- a/test-runner/main.go
+++ b/builder/main.go
@@ -4,8 +4,8 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/codecrafters-io/test-runner/internal/commands"
-	"github.com/codecrafters-io/test-runner/internal/utils"
+	"github.com/codecrafters-io/test-runner-builder/internal/commands"
+	"github.com/codecrafters-io/test-runner-builder/internal/utils"
 	"github.com/getsentry/sentry-go"
 )
 
diff --git a/test-runner/main.goreleaser.yml b/builder/main.goreleaser.yml
similarity index 100%
rename from test-runner/main.goreleaser.yml
rename to builder/main.goreleaser.yml
diff --git a/test-runner/tests/build_image_test.rb b/builder/tests/build_image_test.rb
similarity index 100%
rename from test-runner/tests/build_image_test.rb
rename to builder/tests/build_image_test.rb
diff --git a/test-runner/tests/lib/build_image_command_runner.rb b/builder/tests/lib/build_image_command_runner.rb
similarity index 100%
rename from test-runner/tests/lib/build_image_command_runner.rb
rename to builder/tests/lib/build_image_command_runner.rb
diff --git a/test-runner/tests/lib/buildpack_dockerfile_processor.rb b/builder/tests/lib/buildpack_dockerfile_processor.rb
similarity index 100%
rename from test-runner/tests/lib/buildpack_dockerfile_processor.rb
rename to builder/tests/lib/buildpack_dockerfile_processor.rb
diff --git a/test-runner/tests/lib/code_fixtures.rb b/builder/tests/lib/code_fixtures.rb
similarity index 100%
rename from test-runner/tests/lib/code_fixtures.rb
rename to builder/tests/lib/code_fixtures.rb
diff --git a/test-runner/tests/lib/database_helper.rb b/builder/tests/lib/database_helper.rb
similarity index 100%
rename from test-runner/tests/lib/database_helper.rb
rename to builder/tests/lib/database_helper.rb
diff --git a/test-runner/tests/lib/db/models/application_record.rb b/builder/tests/lib/db/models/application_record.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/application_record.rb
rename to builder/tests/lib/db/models/application_record.rb
diff --git a/test-runner/tests/lib/db/models/buildpack.rb b/builder/tests/lib/db/models/buildpack.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/buildpack.rb
rename to builder/tests/lib/db/models/buildpack.rb
diff --git a/test-runner/tests/lib/db/models/repository.rb b/builder/tests/lib/db/models/repository.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/repository.rb
rename to builder/tests/lib/db/models/repository.rb
diff --git a/test-runner/tests/lib/db/models/submission.rb b/builder/tests/lib/db/models/submission.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/submission.rb
rename to builder/tests/lib/db/models/submission.rb
diff --git a/test-runner/tests/lib/db/models/test_run.rb b/builder/tests/lib/db/models/test_run.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/test_run.rb
rename to builder/tests/lib/db/models/test_run.rb
diff --git a/test-runner/tests/lib/db/models/test_run_result.rb b/builder/tests/lib/db/models/test_run_result.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/test_run_result.rb
rename to builder/tests/lib/db/models/test_run_result.rb
diff --git a/test-runner/tests/lib/db/models/test_runner.rb b/builder/tests/lib/db/models/test_runner.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/test_runner.rb
rename to builder/tests/lib/db/models/test_runner.rb
diff --git a/test-runner/tests/lib/db/models/test_runner_build.rb b/builder/tests/lib/db/models/test_runner_build.rb
similarity index 100%
rename from test-runner/tests/lib/db/models/test_runner_build.rb
rename to builder/tests/lib/db/models/test_runner_build.rb
diff --git a/test-runner/tests/lib/db/schema.rb b/builder/tests/lib/db/schema.rb
similarity index 100%
rename from test-runner/tests/lib/db/schema.rb
rename to builder/tests/lib/db/schema.rb
diff --git a/test-runner/tests/lib/fake_git_repository.rb b/builder/tests/lib/fake_git_repository.rb
similarity index 100%
rename from test-runner/tests/lib/fake_git_repository.rb
rename to builder/tests/lib/fake_git_repository.rb
diff --git a/test-runner/tests/lib/fake_server.rb b/builder/tests/lib/fake_server.rb
similarity index 100%
rename from test-runner/tests/lib/fake_server.rb
rename to builder/tests/lib/fake_server.rb
diff --git a/test-runner/tests/lib/git_api_gateway.rb b/builder/tests/lib/git_api_gateway.rb
similarity index 100%
rename from test-runner/tests/lib/git_api_gateway.rb
rename to builder/tests/lib/git_api_gateway.rb
diff --git a/test-runner/tests/lib/submission_test_runner_actions_builder.rb b/builder/tests/lib/submission_test_runner_actions_builder.rb
similarity index 100%
rename from test-runner/tests/lib/submission_test_runner_actions_builder.rb
rename to builder/tests/lib/submission_test_runner_actions_builder.rb
diff --git a/test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb b/builder/tests/lib/test_runner_actions/await_terminal_build_status.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/await_terminal_build_status.rb
rename to builder/tests/lib/test_runner_actions/await_terminal_build_status.rb
diff --git a/test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb b/builder/tests/lib/test_runner_actions/await_terminal_submission_status.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/await_terminal_submission_status.rb
rename to builder/tests/lib/test_runner_actions/await_terminal_submission_status.rb
diff --git a/test-runner/tests/lib/test_runner_actions/base.rb b/builder/tests/lib/test_runner_actions/base.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/base.rb
rename to builder/tests/lib/test_runner_actions/base.rb
diff --git a/test-runner/tests/lib/test_runner_actions/print_message.rb b/builder/tests/lib/test_runner_actions/print_message.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/print_message.rb
rename to builder/tests/lib/test_runner_actions/print_message.rb
diff --git a/test-runner/tests/lib/test_runner_actions/sleep.rb b/builder/tests/lib/test_runner_actions/sleep.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/sleep.rb
rename to builder/tests/lib/test_runner_actions/sleep.rb
diff --git a/test-runner/tests/lib/test_runner_actions/stream_logs.rb b/builder/tests/lib/test_runner_actions/stream_logs.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/stream_logs.rb
rename to builder/tests/lib/test_runner_actions/stream_logs.rb
diff --git a/test-runner/tests/lib/test_runner_actions/terminate.rb b/builder/tests/lib/test_runner_actions/terminate.rb
similarity index 100%
rename from test-runner/tests/lib/test_runner_actions/terminate.rb
rename to builder/tests/lib/test_runner_actions/terminate.rb
diff --git a/test-runner/tests/lib/tester_downloader.rb b/builder/tests/lib/tester_downloader.rb
similarity index 100%
rename from test-runner/tests/lib/tester_downloader.rb
rename to builder/tests/lib/tester_downloader.rb
diff --git a/test-runner/tests/sample_data/docker_logs.txt b/builder/tests/sample_data/docker_logs.txt
similarity index 100%
rename from test-runner/tests/sample_data/docker_logs.txt
rename to builder/tests/sample_data/docker_logs.txt
diff --git a/test-runner/tests/test_helper.rb b/builder/tests/test_helper.rb
similarity index 100%
rename from test-runner/tests/test_helper.rb
rename to builder/tests/test_helper.rb
diff --git a/download_test_runner.sh b/download_test_runner.sh
new file mode 100755
index 0000000..3c7a51c
--- /dev/null
+++ b/download_test_runner.sh
@@ -0,0 +1,36 @@
+set -e
+set -x
+
+destinationDir="/var/opt/test-runner" # Destination directory
+
+repoOwner="codecrafters-io"                  # GitHub repository owner
+repoName="test-runner"                       # GitHub repository name
+releaseTag="v0.3.67"                         # Release tag to download
+assetName="${releaseTag}_linux_amd64.tar.gz" # Asset name
+downloadedTarPath="$(mktemp)"                # Path to downloaded tar file
+
+# Get the asset ID
+assetId=$(curl -fsSL --header "Authorization: Bearer ${GITHUB_TOKEN}" "https://api.github.com/repos/$repoOwner/$repoName/releases/tags/$releaseTag" | jq -r --arg assetName "$assetName" '.assets[] | select(.name==$assetName) | .id')
+echo "Asset ID: $assetId"
+
+downloadUrl="https://api.github.com/repos/$repoOwner/$repoName/releases/assets/$assetId"
+echo "Download URL: $downloadUrl"
+
+wget --header="Authorization: Bearer ${GITHUB_TOKEN}" --header="Accept: application/octet-stream" -O $downloadedTarPath $downloadUrl
+mkdir -p $destinationDir
+tar xz -C $destinationDir -f $downloadedTarPath
+
+rm -rf $downloadedTarPath
+
+# TODO: Replace this by adding a `--version` flag!
+set +e
+output=$(/var/opt/test-runner/test-runner --help 2>&1)
+exit_code=$?
+echo "$output"
+echo "$output" | grep -qi "unknown command"
+grep_exit_code=$?
+if [ $exit_code -ne 1 ] || [ $grep_exit_code -ne 0 ]; then
+    echo "Test failed: exit code was $exit_code, output was: $output"
+    exit 1
+fi
+set -e

From cc03069e8b1808a7ef8f52c39281280817e0cf12 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:39:45 -0800
Subject: [PATCH 08/13] Update Dockerfile and download_test_runner.sh for test
 runner version 0.3.71

---
 Dockerfile              |  8 ++++++--
 download_test_runner.sh | 15 +--------------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 7e65ab1..aaefeba 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -28,8 +28,12 @@ RUN depot --version
 COPY builder/ /tmp/builder/
 RUN cd /tmp/builder && go build -o /var/opt/test-runner-builder main.go
 
+# Ensure the Go program is installed and working
+RUN /var/opt/test-runner-builder --version
+
+# Download test runner to a directory (mounted during docker builds)
 COPY download_test_runner.sh /tmp/download_test_runner.sh
 RUN --mount=type=secret,id=test_runner_downloader_token,env=GITHUB_TOKEN /tmp/download_test_runner.sh
 
-# Ensure the Go program is installed and working
-RUN /var/opt/test-runner-builder --version
\ No newline at end of file
+# Ensure the test runner is installed and working
+RUN /var/opt/test-runner/test-runner --version
\ No newline at end of file
diff --git a/download_test_runner.sh b/download_test_runner.sh
index 3c7a51c..66dce81 100755
--- a/download_test_runner.sh
+++ b/download_test_runner.sh
@@ -5,7 +5,7 @@ destinationDir="/var/opt/test-runner" # Destination directory
 
 repoOwner="codecrafters-io"                  # GitHub repository owner
 repoName="test-runner"                       # GitHub repository name
-releaseTag="v0.3.67"                         # Release tag to download
+releaseTag="v0.3.71"                         # Release tag to download
 assetName="${releaseTag}_linux_amd64.tar.gz" # Asset name
 downloadedTarPath="$(mktemp)"                # Path to downloaded tar file
 
@@ -21,16 +21,3 @@ mkdir -p $destinationDir
 tar xz -C $destinationDir -f $downloadedTarPath
 
 rm -rf $downloadedTarPath
-
-# TODO: Replace this by adding a `--version` flag!
-set +e
-output=$(/var/opt/test-runner/test-runner --help 2>&1)
-exit_code=$?
-echo "$output"
-echo "$output" | grep -qi "unknown command"
-grep_exit_code=$?
-if [ $exit_code -ne 1 ] || [ $grep_exit_code -ne 0 ]; then
-    echo "Test failed: exit code was $exit_code, output was: $output"
-    exit 1
-fi
-set -e

From 311aff34367d90167596e92646d7df2e0134e3b3 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:43:41 -0800
Subject: [PATCH 09/13] Rename TEST_RUNNER_EXECUTABLE_PATH to
 BUILDER_EXECUTABLE_PATH in tests.

---
 builder/tests/lib/build_image_command_runner.rb | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/builder/tests/lib/build_image_command_runner.rb b/builder/tests/lib/build_image_command_runner.rb
index 42938b6..1e3e35a 100644
--- a/builder/tests/lib/build_image_command_runner.rb
+++ b/builder/tests/lib/build_image_command_runner.rb
@@ -1,4 +1,4 @@
-TEST_RUNNER_EXECUTABLE_PATH = File.expand_path("../../dist/main.out", __dir__)
+BUILDER_EXECUTABLE_PATH = File.expand_path("../../dist/main.out", __dir__)
 TEST_RUNNER_SOURCE_DIR = File.expand_path("../../", __dir__)
 TESTERS_DIR = File.expand_path("../fixtures/testers", __dir__)
 
@@ -18,15 +18,16 @@ def run(build:, test_run: nil)
     FileUtils.rm_rf(tmp_dir)
     FileUtils.cp_r(git_repository.tmp_dir, tmp_dir)
 
+    # This isn't actually being used! We just need a binary present there to test.
     test_runner_dir = Dir.mktmpdir
-    `cp #{TEST_RUNNER_EXECUTABLE_PATH} #{test_runner_dir}/test-runner`
+    `cp #{BUILDER_EXECUTABLE_PATH} #{test_runner_dir}/test-runner`
 
     dockerfile_handle = Tempfile.new
     dockerfile_handle.write(repository.buildpack.processed_dockerfile_contents)
     dockerfile_handle.close
 
     command_parts = [
-      TEST_RUNNER_EXECUTABLE_PATH,
+      BUILDER_EXECUTABLE_PATH,
       "--buildpack-slug='#{repository.buildpack.slug}'",
       "--buildpack-dockerfile-path='#{dockerfile_handle.path}'",
       "--build-id='#{build.id}'",

From 38c10fa66eefe0009e26e05fcbae9cf2e1f497b6 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:45:19 -0800
Subject: [PATCH 10/13] Update GitHub Actions workflow to use 'builder'
 directory and remove old config.

---
 .github/workflows/test.yml  |  8 ++++----
 builder/main.goreleaser.yml | 11 -----------
 2 files changed, 4 insertions(+), 15 deletions(-)
 delete mode 100644 builder/main.goreleaser.yml

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 95b1b87..8744025 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,11 +37,11 @@ jobs:
           ruby-version: 3.3.5
           bundler-cache: true
           cache-version: 5
-          working-directory: test-runner
+          working-directory: build
 
       - name: Run make refresh_test_fixtures
         run: make refresh_test_fixtures
-        working-directory: test-runner
+        working-directory: builder
 
       # Required for pulling git-api and git-daemon
       - name: Authenticate with ghcr.io
@@ -53,7 +53,7 @@ jobs:
 
       - name: Set up Docker
         run: docker compose up -d
-        working-directory: test-runner
+        working-directory: builder
 
       - name: Set up Git
         run: |
@@ -62,7 +62,7 @@ jobs:
 
       - name: Run tests
         run: make test
-        working-directory: test-runner
+        working-directory: builder
         env:
           DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
           DEPOT_PROJECT: ${{ secrets.DEPOT_PROJECT }}
diff --git a/builder/main.goreleaser.yml b/builder/main.goreleaser.yml
deleted file mode 100644
index 6f26c50..0000000
--- a/builder/main.goreleaser.yml
+++ /dev/null
@@ -1,11 +0,0 @@
-builds:
-  - main: ./
-    binary: test-runner
-    env:
-      - CGO_ENABLED=0
-    goarch: [amd64, arm64]
-    goos: [linux, darwin]
-
-archives:
-  - name_template: "{{ .Tag }}_{{ .Os }}_{{ .Arch }}"
-    format: tar.gz

From b79ffc0422d515bec5c97b37964f2e8ae0ca890e Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:46:45 -0800
Subject: [PATCH 11/13] Update working directory in GitHub Actions workflow
 from 'build' to 'builder'

---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8744025..af72d41 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,7 +37,7 @@ jobs:
           ruby-version: 3.3.5
           bundler-cache: true
           cache-version: 5
-          working-directory: build
+          working-directory: builder
 
       - name: Run make refresh_test_fixtures
         run: make refresh_test_fixtures

From eca8cebcab8930154245cd55ca38048ea1160f08 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:53:04 -0800
Subject: [PATCH 12/13] Update test workflow to copy .env.example before
 running tests

---
 .github/workflows/test.yml | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index af72d41..830964e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -61,9 +61,4 @@ jobs:
           git config --global user.name "Your Name"
 
       - name: Run tests
-        run: make test
-        working-directory: builder
-        env:
-          DEPOT_TOKEN: ${{ secrets.DEPOT_TOKEN }}
-          DEPOT_PROJECT: ${{ secrets.DEPOT_PROJECT }}
-          FLY_ACCESS_TOKEN: ${{ secrets.FLY_ACCESS_TOKEN }}
+        run: cp .env.example .env && make test

From d015d379e30770fc495b21d50f7c8a4590606f80 Mon Sep 17 00:00:00 2001
From: Paul Kuruvilla <rohitpaulk@gmail.com>
Date: Sun, 16 Nov 2025 20:54:52 -0800
Subject: [PATCH 13/13] Update test workflow to set working directory for test
 execution.

---
 .github/workflows/test.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 830964e..d777e57 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -62,3 +62,4 @@ jobs:
 
       - name: Run tests
         run: cp .env.example .env && make test
+        working-directory: builder