diff --git a/.claude/hooks/format.sh b/.claude/hooks/format.sh
index a85bfa96..d3ce1cf6 100755
--- a/.claude/hooks/format.sh
+++ b/.claude/hooks/format.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 #
 # Claude Code Hook: Format Files
-# Triggers after Claude edits/writes files and runs nix fmt
+# Triggers after Claude edits/writes files and runs treefmt (via mise)
 #
 # Environment variables provided by Claude Code:
 # - CLAUDE_PROJECT_DIR: Path to the project directory
@@ -75,18 +75,18 @@ main() {
     exit 1
   fi
 
-  log "${YELLOW}Formatting file with nix fmt...${NC}"
+  log "${YELLOW}Formatting file with treefmt...${NC}"
 
   # Change to project directory
   cd "${CLAUDE_PROJECT_DIR}"
 
-  # Run nix fmt on the file
-  if nix fmt "$FILE_PATH" 2>/dev/null; then
+  # Run treefmt on the file
+  if mise exec -- treefmt "$FILE_PATH" 2>/dev/null; then
     log "${GREEN}✓ Successfully formatted: $FILE_PATH${NC}"
     exit 0
   else
     EXIT_CODE=$?
-    log "${RED}✗ nix fmt failed with exit code $EXIT_CODE${NC}"
+    log "${RED}✗ treefmt failed with exit code $EXIT_CODE${NC}"
     log "${RED}This indicates the file has formatting issues that need manual attention${NC}"
 
     # Don't fail the hook - just warn about formatting issues
diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
deleted file mode 100644
index 9fb67ee1..00000000
--- a/.devcontainer/Dockerfile
+++ /dev/null
@@ -1,29 +0,0 @@
-FROM mcr.microsoft.com/devcontainers/base:ubuntu
-
-# Install Nix
-RUN apt-get update && apt-get install -y \
-  curl \
-  xz-utils \
-  sudo \
-  && rm -rf /var/lib/apt/lists/*
-
-# Create vscode user if it doesn't exist
-RUN if ! id -u vscode > /dev/null 2>&1; then \
-  useradd -m -s /bin/bash vscode && \
-  echo "vscode ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers; \
-  fi
-
-# Switch to vscode user for Nix installation
-USER vscode
-WORKDIR /home/vscode
-
-# Install Nix in single-user mode
-RUN curl -L https://nixos.org/nix/install | sh -s -- --no-daemon
-
-# Add Nix to PATH and configure for the shell
-RUN echo '. /home/vscode/.nix-profile/etc/profile.d/nix.sh' >> /home/vscode/.bashrc && \
-  mkdir -p /home/vscode/.config/nix && \
-  echo 'experimental-features = nix-command flakes' >> /home/vscode/.config/nix/nix.conf
-
-# Keep container running
-CMD ["sleep", "infinity"]
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index eb629891..5f511c6d 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -1,17 +1,12 @@
 {
   "name": "claudecode.nvim Development",
-  "build": {
-    "dockerfile": "Dockerfile"
-  },
+  "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
   "features": {
-    "ghcr.io/devcontainers/features/git:1": {}
+    "ghcr.io/devcontainers-extra/features/mise:1": {}
   },
   "customizations": {
     "vscode": {
-      "settings": {
-        "terminal.integrated.defaultProfile.linux": "bash"
-      },
-      "extensions": ["jnoortheen.nix-ide"]
+      "extensions": ["hverlin.mise-vscode"]
     }
   },
   "postCreateCommand": "bash .devcontainer/post-create.sh",
diff --git a/.devcontainer/post-create.sh b/.devcontainer/post-create.sh
index ca9d0f1b..47d8dbaf 100755
--- a/.devcontainer/post-create.sh
+++ b/.devcontainer/post-create.sh
@@ -1,31 +1,33 @@
 #!/bin/bash
+set -euo pipefail
 
-# Source Nix environment
-. /home/vscode/.nix-profile/etc/profile.d/nix.sh
-
-# Verify Nix is available
-if ! command -v nix &>/dev/null; then
-  echo "Error: Nix is not installed properly"
+# Ensure the feature-installed mise is on PATH for this script.
+export PATH="$HOME/.local/bin:/usr/local/bin:$PATH"
+if ! command -v mise &>/dev/null; then
+  echo "Error: mise is not on PATH after the devcontainer feature install" >&2
   exit 1
 fi
 
-echo "✅ Nix is installed and available"
-echo ""
-echo "📦 claudecode.nvim Development Container Ready!"
-echo ""
-echo "To enter the development shell with all dependencies, run:"
-echo "  nix develop"
+# Build deps: PUC Lua builds from source, and the test rocks compile C modules.
+sudo apt-get -o Acquire::Retries=3 update
+sudo apt-get -o Acquire::Retries=3 install -y build-essential libreadline-dev unzip
+
+# Activate mise in interactive shells (puts the toolchain + fixtures/bin on PATH).
+if ! grep -qs 'mise activate bash' "$HOME/.bashrc"; then
+  echo 'eval "$(mise activate bash)"' >>"$HOME/.bashrc"
+fi
+
 echo ""
-echo "This will provide:"
-echo "  - Neovim"
-echo "  - Lua and LuaJIT"
-echo "  - busted (test framework)"
-echo "  - luacheck (linter)"
-echo "  - stylua (formatter)"
-echo "  - All other development tools"
+echo "📦 Provisioning the claudecode.nvim development environment with mise..."
+
+mise trust
+mise install
+mise run setup
+
 echo ""
-echo "You can also run development commands directly:"
-echo "  - make        # Run full validation (format, lint, test)"
-echo "  - make test   # Run tests"
-echo "  - make check  # Run linter"
-echo "  - make format # Format code"
+echo "✅ claudecode.nvim development environment ready."
+echo "   mise run all      # full validation (format, lint, test)"
+echo "   mise run test     # run tests"
+echo "   mise run check    # lint"
+echo "   mise run format   # format"
+echo "   mise tasks        # list all tasks"
diff --git a/.envrc b/.envrc
deleted file mode 100644
index 002c9117..00000000
--- a/.envrc
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/usr/bin/env bash
-
-if ! has nix_direnv_version || ! nix_direnv_version 3.0.7; then
-  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.7/direnvrc" "sha256-RYcUJaRMf8oF5LznDrlCXbkOQrywm0HDv1VjYGaJGdM="
-fi
-
-nix_direnv_manual_reload
-
-use flake .
-
-# Add fixtures/bin to PATH for nvim config aliases
-PATH_add fixtures/bin
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d1a791cc..2f8ad424 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,11 +16,11 @@ concurrency:
   cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
 
 jobs:
+  # Unit/component tests run under LuaJIT with a mocked vim global (busted), so
+  # they do not need a real Neovim binary — hence no neovim-version matrix here.
+  # Real-Neovim coverage lives in the integration-tests job below.
   unit-tests:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        neovim-version: ["stable", "nightly"]
 
     steps:
       - name: Checkout
@@ -29,38 +29,38 @@ jobs:
           fetch-depth: 0
           persist-credentials: false
 
-      - name: Setup Nix
-        uses: nixbuild/nix-quick-install-action@5bb6a3b3abe66fd09bbf250dce8ada94f856a703 # v30
+      # Build deps: PUC Lua builds from source, and the test rocks compile C modules.
+      - name: Install build dependencies
+        run: |
+          sudo apt-get -o Acquire::Retries=3 update
+          sudo apt-get -o Acquire::Retries=3 install -y build-essential libreadline-dev unzip
 
-      - uses: nix-community/cache-nix-action@135667ec418502fa5a3598af6fb9eb733888ce6a # v6.1.3
-        with:
-          primary-key: nix-claudecode-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
-          restore-prefixes-first-match: nix-claudecode-${{ runner.os }}-
-          gc-max-store-size-linux: 2G
-          purge: true
-          purge-prefixes: nix-claudecode-${{ runner.os }}-
-          purge-created: 0
-          purge-primary-key: never
+      - name: Set up mise
+        uses: jdx/mise-action@1648a7812b9aeae629881980618f079932869151 # v4.0.1
 
-      - name: Setup Neovim
-        uses: rhysd/action-setup-vim@8e931b9954b19d4203d5caa5ff5521f3bc21dcc7 # v1.4.2
+      # Cache the rock tree (rebuilt from luarocks.org otherwise); a miss just rebuilds.
+      - name: Cache Lua test rocks
+        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
-          neovim: true
-          version: ${{ matrix.neovim-version }}
+          path: .luarocks
+          key: luarocks-${{ runner.os }}-${{ hashFiles('mise.toml') }}
+
+      - name: Install Lua test rocks
+        run: mise run setup
 
-      - name: Run Luacheck
-        run: nix develop .#ci -c make check
+      - name: Run luacheck
+        run: mise run check
 
       - name: Run tests
-        run: nix develop .#ci -c make test
+        run: mise run test
 
       - name: Check formatting
-        run: nix flake check
+        run: mise run format-check
 
       - name: Generate coverage report
         run: |
           if [ -f "luacov.stats.out" ]; then
-            nix develop .#ci -c luacov
+            mise exec -- luacov
 
             echo "Creating lcov.info from luacov.report.out"
             {
@@ -134,19 +134,8 @@ jobs:
           fetch-depth: 0
           persist-credentials: false
 
-      - name: Setup Nix
-        uses: nixbuild/nix-quick-install-action@5bb6a3b3abe66fd09bbf250dce8ada94f856a703 # v30
-
-      - uses: nix-community/cache-nix-action@135667ec418502fa5a3598af6fb9eb733888ce6a # v6.1.3
-        with:
-          primary-key: nix-claudecode-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
-          restore-prefixes-first-match: nix-claudecode-${{ runner.os }}-
-          gc-max-store-size-linux: 2G
-          purge: true
-          purge-prefixes: nix-claudecode-${{ runner.os }}-
-          purge-created: 0
-          purge-primary-key: never
-
+      # Neovim here comes from action-setup-vim (matrix-driven), independent of
+      # the mise.toml neovim pin used for local dev.
       - name: Setup Neovim
         uses: rhysd/action-setup-vim@8e931b9954b19d4203d5caa5ff5521f3bc21dcc7 # v1.4.2
         with:
@@ -159,4 +148,4 @@ jobs:
           ln -s "$(pwd)" ~/.local/share/nvim/site/pack/vendor/start/claudecode.nvim
 
       - name: Run integration tests
-        run: nix develop .#ci -c ./scripts/run_integration_tests_individually.sh
+        run: ./scripts/run_integration_tests_individually.sh
diff --git a/.gitignore b/.gitignore
index 37174f69..a5cb8bdb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,9 @@ luac.out
 *.zip
 *.tar.gz
 
+# Project-local Lua rock tree built by `mise run setup`
+/.luarocks/
+
 # Object files
 *.o
 *.os
diff --git a/AGENTS.md b/AGENTS.md
index e4f4d014..2e84e336 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -10,12 +10,13 @@
 
 ## Build, Test, and Development Commands
 
-- `make check`: Syntax checks + `luacheck` on `lua/` and `tests/`.
-- `make format`: Format with StyLua (via Nix `nix fmt` in this repo).
-- `make test`: Run Busted tests with coverage (outputs `luacov.stats.out`).
-- `make clean`: Remove coverage artifacts.
+- Setup (one time): install [mise](https://mise.jdx.dev), then `mise install && mise run setup` to provision the toolchain and build the Lua test rocks. Activate mise in your shell (`eval "$(mise activate bash)"` in your rc) so bare tools like `busted`/`nvim` are on PATH; otherwise prefix with `mise exec --`. Run `mise tasks` to list all tasks.
+- `mise run check`: Syntax checks + `luacheck` on `lua/` and `tests/`.
+- `mise run format`: Format the tree with treefmt (replaces the former `nix fmt`).
+- `mise run test`: Run Busted tests with coverage (outputs `luacov.stats.out`).
+- `mise run clean`: Remove coverage artifacts.
   Examples:
-- Run all tests: `make test`
+- Run all tests: `mise run test`
 - Run one file: `busted -v tests/unit/terminal_spec.lua`
 
 ## Coding Style & Naming Conventions
@@ -32,13 +33,13 @@
 - File naming: `*_spec.lua` or `*_test.lua` under `tests/unit` or `tests/integration`.
 - Mocks/helpers: place in `tests/mocks` and `tests/helpers`; prefer pure‑Lua mocks.
 - Coverage: keep high signal; exercise server, tools, diff, and terminal paths.
-- Quick tip: prefer `make test` (it sets `LUA_PATH` and coverage flags).
+- Quick tip: prefer `mise run test` (it sets `LUA_PATH` and coverage flags).
 
 ## Commit & Pull Request Guidelines
 
 - Commits: Use Conventional Commits (e.g., `feat:`, `fix:`, `docs:`, `test:`, `chore:`). Keep messages imperative and scoped.
 - PRs: include a clear description, linked issues, repro steps, and tests. Update docs (`README.md`, `ARCHITECTURE.md`, or `DEVELOPMENT.md`) when behavior changes.
-- Pre-flight: run `make format`, `make check`, and `make test`. Attach screenshots or terminal recordings for UX-visible changes (diff flows, terminal behavior).
+- Pre-flight: run `mise run all` (format, lint, test). Attach screenshots or terminal recordings for UX-visible changes (diff flows, terminal behavior).
 
 ## Security & Configuration Tips
 
diff --git a/CLAUDE.md b/CLAUDE.md
index 7a900690..19437315 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -10,32 +10,36 @@ claudecode.nvim - A Neovim plugin that implements the same WebSocket-based MCP p
 
 ### Testing
 
-- `make test` - Run all tests using busted with coverage
+- `mise run test` - Run all tests using busted with coverage
 - `busted tests/unit/specific_spec.lua` - Run specific test file
 - `busted --coverage -v` - Run tests with coverage
 
 ### Code Quality
 
-- `make check` - Check Lua syntax and run luacheck
-- `make format` - Format code with stylua (or nix fmt if available)
+- `mise run check` - Check Lua syntax and run luacheck
+- `mise run format` - Format code with treefmt
 - `luacheck lua/ tests/ --no-unused-args --no-max-line-length` - Direct linting
 
 ### Build Commands
 
-- `make` - **RECOMMENDED**: Run formatting, linting, and testing (complete validation)
-- `make all` - Run check and format (default target)
-- `make test` - Run all tests using busted with coverage
-- `make check` - Check Lua syntax and run luacheck
-- `make format` - Format code with stylua (or nix fmt if available)
-- `make clean` - Remove generated test files
-- `make help` - Show available commands
+- `mise run all` - **RECOMMENDED**: Run formatting, linting, and testing (complete validation)
+- `mise run test` - Run all tests using busted with coverage
+- `mise run check` - Check Lua syntax and run luacheck
+- `mise run format` - Format code with treefmt
+- `mise run clean` - Remove generated test files
+- `mise tasks` - List available tasks
 
-**Best Practice**: Always use `make` at the end of editing sessions for complete validation.
+**Best Practice**: Always use `mise run all` at the end of editing sessions for complete validation.
 
-### Development with Nix
+### Development with mise
 
-- `nix develop` - Enter development shell with all dependencies
-- `nix fmt` - Format all files using nix formatter
+The dev toolchain is provisioned by [mise](https://mise.jdx.dev) (see `mise.toml`), which replaced the former Nix flake devShell.
+
+- `mise install` - Install all tools (Neovim, LuaJIT, formatters, etc.)
+- `mise run setup` - Build the Lua test rocks (busted/luacheck/luacov) into `./.luarocks`
+- `mise run all` - Format, lint, and test
+- `mise run format` - Format all files with treefmt
+- Activate mise in your shell so its tools (and `fixtures/bin`) are on PATH — add `eval "$(mise activate bash)"` (or `zsh`/`fish`) to your shell rc. (`mise run <task>` works without activation.)
 
 ### Integration Testing with Fixtures
 
@@ -156,7 +160,7 @@ claudecode.nvim implements **100% feature parity** with Anthropic's official VS
 
 ### Protocol Validation
 
-Run `make test` to verify MCP compliance:
+Run `mise run test` to verify MCP compliance:
 
 - **Tool Format Validation**: All tools return proper MCP structure
 - **Schema Compliance**: JSON schemas validated against VS Code specs
@@ -184,12 +188,11 @@ Test files follow the pattern `*_spec.lua` or `*_test.lua` and use the busted fr
 **Test Pattern**: Run specific test files during development:
 
 ```bash
-# Run specific tool tests with proper LUA_PATH
-export LUA_PATH="./lua/?.lua;./lua/?/init.lua;./?.lua;./?/init.lua;$LUA_PATH"
+# Run a specific test file (mise sets LUA_PATH automatically)
 busted tests/unit/tools/specific_tool_spec.lua --verbose
 
-# Or use make for full validation
-make test  # Recommended for complete validation
+# Or run the whole suite
+mise run test  # Recommended for complete validation
 ```
 
 **Coverage Metrics**:
@@ -371,13 +374,11 @@ When updating the version number for a new release, you must update **ALL** of t
    ```
 
 2. **`scripts/claude_interactive.sh`** - Multiple client version references:
-
    - Line ~52: `"version": "0.2.0"` (handshake)
    - Line ~223: `"version": "0.2.0"` (initialize)
    - Line ~309: `"version": "0.2.0"` (reconnect)
 
 3. **`scripts/lib_claude.sh`** - ClaudeCodeNvim version:
-
    - Line ~120: `"version": "0.2.0"` (init message)
 
 4. **`CHANGELOG.md`** - Add new release section with:
@@ -396,7 +397,7 @@ gh pr list --state merged --base main --json number,title,mergedAt,url --jq 'sor
 git log --oneline v0.1.0..HEAD
 
 # Always run before committing
-make
+mise run all
 
 # Verify no old version references remain
 rg "0\.1\.0" .  # Should only show CHANGELOG.md historical entries
@@ -406,15 +407,15 @@ rg "0\.1\.0" .  # Should only show CHANGELOG.md historical entries
 
 ### Pre-commit Requirements
 
-**ALWAYS run `make` before committing any changes.** This runs code quality checks and formatting that must pass for CI to succeed. Never skip this step - many PRs fail CI because contributors don't run the build commands before committing.
+**ALWAYS run `mise run all` before committing any changes.** This runs code quality checks and formatting that must pass for CI to succeed. Never skip this step - many PRs fail CI because contributors don't run the build commands before committing.
 
 ### Recommended Development Flow
 
 1. **Start Development**: Use existing tests and documentation to understand the system
 2. **Make Changes**: Follow existing patterns and conventions in the codebase
-3. **Validate Work**: Run `make` to ensure formatting, linting, and tests pass
+3. **Validate Work**: Run `mise run all` to ensure formatting, linting, and tests pass
 4. **Document Changes**: Update relevant documentation (this file, PROTOCOL.md, etc.)
-5. **Commit**: Only commit after successful `make` execution
+5. **Commit**: Only commit after successful `mise run all` execution
 
 ### Integration Development Guidelines
 
@@ -424,7 +425,7 @@ rg "0\.1\.0" .  # Should only show CHANGELOG.md historical entries
 2. **Create Fixture Configuration**: **REQUIRED** - Add a complete Neovim config in `fixtures/[integration-name]/`
 3. **Test Integration**: Use fixture to verify functionality with `vv [integration-name]`
 4. **Update Documentation**: Add integration to fixtures list and relevant tool documentation
-5. **Run Full Test Suite**: Ensure `make` passes with new integration
+5. **Run Full Test Suite**: Ensure `mise run all` passes with new integration
 
 **Fixture Requirements**:
 
@@ -472,14 +473,14 @@ error({
 - **Zero Warnings**: All code must pass luacheck with 0 warnings/errors
 - **MCP Compliance**: All tools must return proper MCP format with JSON-stringified content
 - **VS Code Compatibility**: New tools must match VS Code extension behavior exactly
-- **Consistent Formatting**: Use `nix fmt` or `stylua` for consistent code style
+- **Consistent Formatting**: Use `mise run format` (treefmt) for consistent code style
 - **Documentation**: Update CLAUDE.md for architectural changes, PROTOCOL.md for protocol changes
 
 ### Development Quality Gates
 
-1. **`make check`** - Syntax and linting (0 warnings required)
-2. **`make test`** - All tests passing (320/320 success rate required)
-3. **`make format`** - Consistent code formatting
+1. **`mise run check`** - Syntax and linting (0 warnings required)
+2. **`mise run test`** - All tests passing (320/320 success rate required)
+3. **`mise run format`** - Consistent code formatting
 4. **MCP Validation** - Tools return proper format structure
 5. **Integration Test** - End-to-end protocol flow verification
 
@@ -489,11 +490,7 @@ error({
 
 **Test Failures with LUA_PATH**:
 
-```bash
-# Tests can't find modules - use proper LUA_PATH
-export LUA_PATH="./lua/?.lua;./lua/?/init.lua;./?.lua;./?/init.lua;$LUA_PATH"
-busted tests/unit/specific_test.lua
-```
+`mise` sets `LUA_PATH`/`LUA_CPATH` automatically (see `mise.toml` `[env]`), so prefer `mise run test` or run `busted` through the activated mise environment (`mise exec -- busted ...`). If a module still can't be found, you're likely running `busted` outside the mise environment.
 
 **JSON Format Issues**:
 
diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index ca704373..02545642 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -2,6 +2,17 @@
 
 Quick guide for contributors to the claudecode.nvim project.
 
+## Development Environment
+
+The toolchain (Neovim, LuaJIT, formatters, test runners) is provisioned by [mise](https://mise.jdx.dev) via `mise.toml`. After installing mise:
+
+```bash
+mise install      # install all tools (builds Lua/LuaJIT from source)
+mise run setup     # build the Lua test rocks (busted/luacheck/luacov) into ./.luarocks
+```
+
+Activate mise in your shell — add `eval "$(mise activate bash)"` (or `zsh`/`fish`) to your shell rc, per the [mise docs](https://mise.jdx.dev/getting-started.html) — so its tools are on PATH. Common tasks: `mise run all` (format + lint + test), `mise run test`, `mise run check`, `mise run format` — run `mise tasks` to list them all. (`mise run <task>` works even without shell activation.)
+
 ## Project Structure
 
 ```none
@@ -54,19 +65,16 @@ claudecode.nvim/
 ## Development Priorities
 
 1. **Advanced MCP Tools**
-
    - Add Neovim-specific tools (LSP integration, diagnostics, Telescope integration)
    - Implement diffview.nvim integration for the diff provider system
    - Add Git integration tools (branch info, status, etc.)
 
 2. **Performance Optimization**
-
    - Monitor WebSocket server performance under load
    - Optimize selection tracking for large files
    - Fine-tune debouncing and event handling
 
 3. **User Experience**
-
    - Add more user commands and keybindings
    - Improve error messages and user feedback
    - Create example configurations for popular setups
@@ -82,34 +90,31 @@ Run tests using:
 
 ```bash
 # Run all tests
-make test
+mise run test
 
 # Run specific test file
 nvim --headless -u tests/minimal_init.lua -c "lua require('tests.unit.config_spec')"
 
 # Run linting
-make check
+mise run check
 
 # Format code
-make format
+mise run format
 ```
 
 ## Implementation Guidelines
 
 1. **Error Handling**
-
    - All public functions should have error handling
    - Return `success, result_or_error` pattern
    - Log meaningful error messages
 
 2. **Performance**
-
    - Minimize impact on editor performance
    - Debounce event handlers
    - Use asynchronous operations where possible
 
 3. **Compatibility**
-
    - Support Neovim >= 0.8.0
    - Zero external dependencies (pure Lua implementation)
    - Follow Neovim plugin best practices
diff --git a/Makefile b/Makefile
deleted file mode 100644
index 2c2b329e..00000000
--- a/Makefile
+++ /dev/null
@@ -1,50 +0,0 @@
-.PHONY: check format test clean
-
-# Default target
-all: format check test
-
-# Detect if we are already inside a Nix shell
-ifeq (,$(IN_NIX_SHELL))
-NIX_PREFIX := nix develop .#ci -c
-else
-NIX_PREFIX :=
-endif
-
-# Check for syntax errors
-check:
-	@echo "Checking Lua files for syntax errors..."
-	$(NIX_PREFIX) find lua -name "*.lua" -type f -exec lua -e "assert(loadfile('{}'))" \;
-	@echo "Running luacheck..."
-	$(NIX_PREFIX) luacheck lua/ tests/ --no-unused-args --no-max-line-length
-
-# Format all files
-format:
-	nix fmt
-
-# Run tests
-test:
-	@echo "Running all tests..."
-	@export LUA_PATH="./lua/?.lua;./lua/?/init.lua;./?.lua;./?/init.lua;$$LUA_PATH"; \
-	TEST_FILES=$$(find tests -type f -name "*_test.lua" -o -name "*_spec.lua" | sort); \
-	echo "Found test files:"; \
-	echo "$$TEST_FILES"; \
-	if [ -n "$$TEST_FILES" ]; then \
-		$(NIX_PREFIX) busted --coverage -v $$TEST_FILES; \
-	else \
-		echo "No test files found"; \
-	fi
-
-# Clean generated files
-clean:
-	@echo "Cleaning generated files..."
-	@rm -f luacov.report.out luacov.stats.out
-	@rm -f tests/lcov.info
-
-# Print available commands
-help:
-	@echo "Available commands:"
-	@echo "  make check  - Check for syntax errors"
-	@echo "  make format - Format all files (uses nix fmt or stylua)"
-	@echo "  make test   - Run tests"
-	@echo "  make clean  - Clean generated files"
-	@echo "  make help   - Print this help message"
diff --git a/README.md b/README.md
index 6e85012e..8c485046 100644
--- a/README.md
+++ b/README.md
@@ -781,7 +781,7 @@ opts = {
 
 ## Contributing
 
-See [DEVELOPMENT.md](./DEVELOPMENT.md) for build instructions and development guidelines. Tests can be run with `make test`.
+See [DEVELOPMENT.md](./DEVELOPMENT.md) for build instructions and development guidelines. Tests can be run with `mise run test`.
 
 ## License
 
diff --git a/fixtures/repro/example/README.md b/fixtures/repro/example/README.md
index 59980099..60f1e009 100644
--- a/fixtures/repro/example/README.md
+++ b/fixtures/repro/example/README.md
@@ -42,7 +42,6 @@ The Neovim config lives at `fixtures/repro/init.lua`.
 A basic end-to-end diff flow you can use to sanity-check the environment:
 
 1. Start Claude:
-
    - press `<leader>ac` (starts the server if needed, then opens the terminal), **or**
    - run `:ClaudeCodeStart` then `:ClaudeCode`
 
diff --git a/flake.lock b/flake.lock
deleted file mode 100644
index 8d99e0d2..00000000
--- a/flake.lock
+++ /dev/null
@@ -1,113 +0,0 @@
-{
-  "nodes": {
-    "flake-utils": {
-      "inputs": {
-        "systems": "systems"
-      },
-      "locked": {
-        "lastModified": 1731533236,
-        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1753694789,
-        "narHash": "sha256-cKgvtz6fKuK1Xr5LQW/zOUiAC0oSQoA9nOISB0pJZqM=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "dc9637876d0dcc8c9e5e22986b857632effeb727",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixos-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "nixpkgs-reviewfixer": {
-      "locked": {
-        "lastModified": 1776877367,
-        "narHash": "sha256-EHq1/OX139R1RvBzOJ0aMRT3xnWyqtHBRUBuO1gFzjI=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "0726a0ecb6d4e08f6adced58726b95db924cef57",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixos-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "nixpkgs_2": {
-      "locked": {
-        "lastModified": 1747958103,
-        "narHash": "sha256-qmmFCrfBwSHoWw7cVK4Aj+fns+c54EBP8cGqp/yK410=",
-        "owner": "nixos",
-        "repo": "nixpkgs",
-        "rev": "fe51d34885f7b5e3e7b59572796e1bcb427eccb1",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nixos",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs",
-        "nixpkgs-reviewfixer": "nixpkgs-reviewfixer",
-        "treefmt-nix": "treefmt-nix"
-      }
-    },
-    "systems": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
-    },
-    "treefmt-nix": {
-      "inputs": {
-        "nixpkgs": "nixpkgs_2"
-      },
-      "locked": {
-        "lastModified": 1753772294,
-        "narHash": "sha256-8rkd13WfClfZUBIYpX5dvG3O9V9w3K9FPQ9rY14VtBE=",
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "rev": "6b9214fffbcf3f1e608efa15044431651635ca83",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "treefmt-nix",
-        "type": "github"
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}
diff --git a/flake.nix b/flake.nix
deleted file mode 100644
index 1326b9a4..00000000
--- a/flake.nix
+++ /dev/null
@@ -1,120 +0,0 @@
-{
-  description = "Claude Code Neovim plugin development environment";
-
-  inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
-    # Separate nixpkgs pin used only to build reviewfixer. The main pin is
-    # held back to avoid CI/formatter churn, but reviewfixer requires
-    # Go >= 1.26.2. Remove `nixpkgs-reviewfixer` (and `pkgsReviewfixer`
-    # below) once the main pin includes Go >= 1.26.2
-    # (check: `nix eval nixpkgs#go.version`).
-    #
-    # Note: `nix flake update` (no `--select`) bumps both inputs to the
-    # same rev, silently collapsing this version gap. Use
-    # `nix flake update nixpkgs-reviewfixer` to update this input alone.
-    nixpkgs-reviewfixer.url = "github:NixOS/nixpkgs/nixos-unstable";
-    flake-utils.url = "github:numtide/flake-utils";
-    treefmt-nix.url = "github:numtide/treefmt-nix";
-  };
-
-  outputs = { self, nixpkgs, nixpkgs-reviewfixer, flake-utils, treefmt-nix, ... }:
-    flake-utils.lib.eachDefaultSystem (system:
-      let
-        pkgs = import nixpkgs {
-          inherit system;
-
-          config.allowUnfreePredicate = pkg: builtins.elem (pkgs.lib.getName pkg) [
-            "claude-code"
-          ];
-        };
-
-        pkgsReviewfixer = import nixpkgs-reviewfixer { inherit system; };
-
-        reviewfixer = pkgsReviewfixer.buildGoModule rec {
-          pname = "reviewfixer";
-          version = "0.1.0-beta.0";
-
-          src = pkgsReviewfixer.fetchFromGitHub {
-            owner = "ThomasK33";
-            repo = "reviewfixer";
-            rev = "v${version}";
-            hash = "sha256-hrnSm7ttpyUAtkre9micI2n9smKgzX5AmUcj3bJQjbU=";
-          };
-
-          vendorHash = "sha256-yIWbmHFxmOeXBm5TMRsupy33DC6VAUYvZNSz5wa1yxA=";
-
-          # Upstream tests shell out to `git`, which isn't available in the
-          # Nix build sandbox. Skip the test phase here.
-          doCheck = false;
-
-          meta = with pkgsReviewfixer.lib; {
-            description = "Local harness for working through review feedback on Graphite-managed stacked PRs";
-            homepage = "https://github.com/ThomasK33/reviewfixer";
-            license = licenses.mit;
-            mainProgram = "reviewfixer";
-          };
-        };
-
-        treefmt = treefmt-nix.lib.evalModule pkgs {
-          projectRootFile = "flake.nix";
-          programs = {
-            stylua.enable = true;
-            nixpkgs-fmt.enable = true;
-            prettier.enable = true;
-            shfmt.enable = true;
-            actionlint.enable = true;
-            zizmor.enable = true;
-            shellcheck.enable = true;
-          };
-          settings.formatter.shellcheck.options = [ "--exclude=SC1091,SC2016" ];
-          settings.formatter.prettier.excludes = [
-            # Exclude lazy.nvim lock files as they are auto-generated
-            # and will be reformatted by lazy on each package update
-            "fixtures/*/lazy-lock.json"
-          ];
-        };
-
-        # CI-specific packages (minimal set for testing and linting)
-        ciPackages = with pkgs; [
-          lua5_1
-          luajitPackages.luacheck
-          luajitPackages.busted
-          luajitPackages.luacov
-          neovim
-          treefmt.config.build.wrapper
-          findutils
-        ];
-
-        # Development packages (additional tools for development)
-        devPackages = with pkgs; [
-          ast-grep
-          luarocks
-          gnumake
-          websocat
-          jq
-          fzf
-          reviewfixer
-          # claude-code
-        ];
-      in
-      {
-        # Format the source tree
-        formatter = treefmt.config.build.wrapper;
-
-        # Check formatting
-        checks.formatting = treefmt.config.build.check self;
-
-        devShells = {
-          # Minimal CI environment
-          ci = pkgs.mkShell {
-            buildInputs = ciPackages;
-          };
-
-          # Full development environment
-          default = pkgs.mkShell {
-            buildInputs = ciPackages ++ devPackages;
-          };
-        };
-      }
-    );
-}
diff --git a/mise.lock b/mise.lock
new file mode 100644
index 00000000..91bc9474
--- /dev/null
+++ b/mise.lock
@@ -0,0 +1,165 @@
+# @generated - this file is auto-generated by `mise lock` https://mise.en.dev/dev-tools/mise-lock.html
+
+[[tools.actionlint]]
+version = "1.7.12"
+backend = "aqua:rhysd/actionlint"
+
+[tools.actionlint."platforms.linux-x64"]
+checksum = "sha256:8aca8db96f1b94770f1b0d72b6dddcb1ebb8123cb3712530b08cc387b349a3d8"
+url = "https://github.com/rhysd/actionlint/releases/download/v1.7.12/actionlint_1.7.12_linux_amd64.tar.gz"
+provenance = "github-attestations"
+
+[tools.actionlint."platforms.macos-arm64"]
+checksum = "sha256:aba9ced2dee8d27fecca3dc7feb1a7f9a52caefa1eb46f3271ea66b6e0e6953f"
+url = "https://github.com/rhysd/actionlint/releases/download/v1.7.12/actionlint_1.7.12_darwin_arm64.tar.gz"
+provenance = "github-attestations"
+
+[[tools.fzf]]
+version = "0.73.1"
+backend = "aqua:junegunn/fzf"
+
+[tools.fzf."platforms.linux-x64"]
+checksum = "sha256:f3252c2c366bc1700d3c85781ec8c9695998927ac127870eb049ceea2d540f8a"
+url = "https://github.com/junegunn/fzf/releases/download/v0.73.1/fzf-0.73.1-linux_amd64.tar.gz"
+
+[tools.fzf."platforms.macos-arm64"]
+checksum = "sha256:d27fd68c04fb9b42f7c73a3f7d38069a74d308e40174f64a072c747213e97286"
+url = "https://github.com/junegunn/fzf/releases/download/v0.73.1/fzf-0.73.1-darwin_arm64.tar.gz"
+
+[[tools."github:numtide/treefmt"]]
+version = "2.5.0"
+backend = "github:numtide/treefmt"
+
+[tools."github:numtide/treefmt"."platforms.linux-x64"]
+checksum = "sha256:95f707bf9666d08b50888b116768fd77f042ad5af92aa3b795f063160e72758f"
+url = "https://github.com/numtide/treefmt/releases/download/v2.5.0/treefmt_2.5.0_linux_amd64.tar.gz"
+url_api = "https://api.github.com/repos/numtide/treefmt/releases/assets/391045232"
+
+[tools."github:numtide/treefmt"."platforms.macos-arm64"]
+checksum = "sha256:a3cdfa8e92eb7c302bb851f73800187e75d5789f2a75835b403b158d77b2c376"
+url = "https://github.com/numtide/treefmt/releases/download/v2.5.0/treefmt_2.5.0_darwin_arm64.tar.gz"
+url_api = "https://api.github.com/repos/numtide/treefmt/releases/assets/391045242"
+
+[[tools.jq]]
+version = "1.8.1"
+backend = "aqua:jqlang/jq"
+
+[tools.jq."platforms.linux-x64"]
+checksum = "sha256:020468de7539ce70ef1bceaf7cde2e8c4f2ca6c3afb84642aabc5c97d9fc2a0d"
+url = "https://github.com/jqlang/jq/releases/download/jq-1.8.1/jq-linux-amd64"
+provenance = "github-attestations"
+
+[tools.jq."platforms.macos-arm64"]
+checksum = "sha256:a9fe3ea2f86dfc72f6728417521ec9067b343277152b114f4e98d8cb0e263603"
+url = "https://github.com/jqlang/jq/releases/download/jq-1.8.1/jq-macos-arm64"
+provenance = "github-attestations"
+
+[[tools.lua]]
+version = "5.5.0"
+backend = "vfox:mise-plugins/vfox-lua"
+
+[tools.lua."platforms.linux-x64"]
+url = "https://www.lua.org/ftp/lua-5.5.0.tar.gz"
+
+[tools.lua."platforms.macos-arm64"]
+url = "https://www.lua.org/ftp/lua-5.5.0.tar.gz"
+
+[[tools.luajit]]
+version = "2.1.1744318430"
+backend = "conda:luajit"
+
+[tools.luajit.options]
+channel = "conda-forge"
+
+[tools.luajit."platforms.macos-arm64"]
+checksum = "sha256:51cadbc5cc111fb0f8804c501603e22d03af38285f75f393c289b254408f47ed"
+url = "https://conda.anaconda.org/conda-forge/osx-arm64/luajit-2.1.1744318430-h1a92334_0.conda"
+conda_deps = []
+
+[[tools.neovim]]
+version = "0.12.2"
+backend = "vfox:mise-plugins/vfox-neovim"
+
+[tools.neovim."platforms.linux-x64"]
+url = "https://github.com/neovim/neovim/releases/download/v0.12.2/nvim-linux-x86_64.tar.gz"
+
+[tools.neovim."platforms.macos-arm64"]
+url = "https://github.com/neovim/neovim/releases/download/v0.12.2/nvim-macos-arm64.tar.gz"
+
+[[tools.node]]
+version = "26.3.0"
+backend = "core:node"
+
+[tools.node."platforms.linux-x64"]
+checksum = "sha256:a6e65cc653e40c1653b77742f9185dbce3ff1f99fa2746d211bddb53530ef206"
+url = "https://nodejs.org/dist/v26.3.0/node-v26.3.0-linux-x64.tar.gz"
+
+[tools.node."platforms.macos-arm64"]
+checksum = "sha256:77ef7f7a15aa757c2ca19d63cf41c8d9eb3b18590ebc6883871310787d8c6b6c"
+url = "https://nodejs.org/dist/v26.3.0/node-v26.3.0-darwin-arm64.tar.gz"
+
+[[tools.prettier]]
+version = "3.8.3"
+backend = "npm:prettier"
+
+[[tools.shellcheck]]
+version = "0.11.0"
+backend = "aqua:koalaman/shellcheck"
+
+[tools.shellcheck."platforms.linux-x64"]
+checksum = "sha256:8c3be12b05d5c177a04c29e3c78ce89ac86f1595681cab149b65b97c4e227198"
+url = "https://github.com/koalaman/shellcheck/releases/download/v0.11.0/shellcheck-v0.11.0.linux.x86_64.tar.xz"
+
+[tools.shellcheck."platforms.macos-arm64"]
+checksum = "sha256:56affdd8de5527894dca6dc3d7e0a99a873b0f004d7aabc30ae407d3f48b0a79"
+url = "https://github.com/koalaman/shellcheck/releases/download/v0.11.0/shellcheck-v0.11.0.darwin.aarch64.tar.xz"
+
+[[tools.shfmt]]
+version = "3.13.1"
+backend = "aqua:mvdan/sh"
+
+[tools.shfmt."platforms.linux-x64"]
+checksum = "sha256:fb096c5d1ac6beabbdbaa2874d025badb03ee07929f0c9ff67563ce8c75398b1"
+url = "https://github.com/mvdan/sh/releases/download/v3.13.1/shfmt_v3.13.1_linux_amd64"
+
+[tools.shfmt."platforms.macos-arm64"]
+checksum = "sha256:9680526be4a66ea1ffe988ed08af58e1400fe1e4f4aef5bd88b20bb9b3da33f8"
+url = "https://github.com/mvdan/sh/releases/download/v3.13.1/shfmt_v3.13.1_darwin_arm64"
+
+[[tools.stylua]]
+version = "2.5.2"
+backend = "aqua:JohnnyMorganz/StyLua"
+
+[tools.stylua."platforms.linux-x64"]
+checksum = "sha256:ca6f1cf52eaf69e6632b81acef9c197aa24b85eb30d2455a35e7dbe28ae77c72"
+url = "https://github.com/JohnnyMorganz/StyLua/releases/download/v2.5.2/stylua-linux-x86_64-musl.zip"
+
+[tools.stylua."platforms.macos-arm64"]
+checksum = "sha256:92ff0889e16324801bc072692974bb67f8161e62010fc90f96c62a17f81f32c7"
+url = "https://github.com/JohnnyMorganz/StyLua/releases/download/v2.5.2/stylua-macos-aarch64.zip"
+
+[[tools.websocat]]
+version = "1.14.1"
+backend = "aqua:vi/websocat"
+
+[tools.websocat."platforms.linux-x64"]
+checksum = "sha256:66f8dd3a0394761556339117f8bb5123bddefd44e087af2a72ec22b0bd08d514"
+url = "https://github.com/vi/websocat/releases/download/v1.14.1/websocat.x86_64-unknown-linux-musl"
+
+[tools.websocat."platforms.macos-arm64"]
+checksum = "sha256:45521ba59a6604785543406bf8e398ce7d565d54c09657176afba795dd28f191"
+url = "https://github.com/vi/websocat/releases/download/v1.14.1/websocat.x86_64-apple-darwin"
+
+[[tools.zizmor]]
+version = "1.25.2"
+backend = "aqua:zizmorcore/zizmor"
+
+[tools.zizmor."platforms.linux-x64"]
+checksum = "sha256:aa1facd105f0d83fe5c55b1adcd9d7417de5d83aa27471f91dc0b66cf3803577"
+url = "https://github.com/zizmorcore/zizmor/releases/download/v1.25.2/zizmor-x86_64-unknown-linux-gnu.tar.gz"
+provenance = "github-attestations"
+
+[tools.zizmor."platforms.macos-arm64"]
+checksum = "sha256:624ef0e09521aecd862126be0f6d7754669af2646750d68ac48a114be33c3146"
+url = "https://github.com/zizmorcore/zizmor/releases/download/v1.25.2/zizmor-aarch64-apple-darwin.tar.gz"
+provenance = "github-attestations"
diff --git a/mise.toml b/mise.toml
new file mode 100644
index 00000000..f07282f9
--- /dev/null
+++ b/mise.toml
@@ -0,0 +1,149 @@
+# mise — development environment for claudecode.nvim
+#
+# Replaces the former Nix flake devShell. Quick start:
+#
+#   mise install      # provision all tools
+#   mise run setup     # build the Lua test rocks (busted/luacheck/luacov)
+#   mise run all       # format + lint + test
+#
+# Run `mise tasks` to list everything below.
+#
+# Tool versions are pinned (mise.lock records resolved checksums; see [settings]).
+# The test rocks built by `mise run setup` (busted/luacheck/luacov) pin only their
+# top-level versions; transitive deps are resolved by LuaRocks at build time.
+
+[settings]
+# Maintain a committed mise.lock pinning resolved URLs + checksums for the
+# binary-download tools (the integrity role flake.lock used to play).
+# Caveats: the conda-backed luajit only locks the platform it was resolved on
+# (Linux CI backfills its entry on first install); source-built tools (lua,
+# neovim) and npm-backed prettier record a URL/version but no checksum.
+# Regenerate with: mise lock -p linux-x64,macos-arm64
+lockfile = true
+
+[tools]
+# LuaJIT is the runtime Neovim embeds, and the test suite *requires* it: the
+# blocking-diff tools yield coroutines across pcall/C-call boundaries, which
+# PUC Lua 5.1 cannot do. busted/luacheck/luacov all run under LuaJIT.
+luajit = "2.1.1744318430"
+# PUC Lua 5.1 is installed only for its bundled LuaRocks, which `mise run
+# setup` uses to build the test rocks *targeting LuaJIT* (luarocks --lua-dir).
+# (The LuaJIT plugin does not ship a LuaRocks.)
+lua = "5.5.0"
+# Neovim for the integration test suite and local plugin testing.
+neovim = "0.12.2"
+
+# Node provides the runtime for prettier (installed via the npm backend).
+node = "26.3.0"
+
+# treefmt drives every formatter/linter below (replaces `nix fmt`).
+"github:numtide/treefmt" = "2.5.0"
+stylua = "2.5.2"
+prettier = "3.8.3"
+shfmt = "3.13.1"
+shellcheck = "0.11.0"
+actionlint = "1.7.12"
+zizmor = "1.25.2"
+
+# Developer tooling (formerly the flake's devPackages).
+# websocat + jq drive the manual WebSocket test scripts in scripts/; fzf backs
+# the fixtures/bin config picker. They stay global because those are interactive
+# helpers run directly (not via `mise run`), so they must be on the shell PATH.
+# reviewfixer is intentionally NOT here — it is scoped to the `reviewfix` task
+# below so normal `mise install`/CI don't fetch the beta binary.
+websocat = "1.14.1"
+jq = "1.8.1"
+fzf = "0.73.1"
+
+[env]
+# Lua test rocks (busted/luacheck/luacov) live in a project-local tree that
+# `mise run setup` populates. fixtures/bin holds the nvim-config helpers
+# (vv/vve/list-configs/repro). Both go on PATH when mise is active.
+_.path = [".luarocks/bin", "fixtures/bin"]
+# Resolve the plugin's modules, test helpers (e.g. require("tests.busted_setup")),
+# and the rock tree from any CWD when running busted/luacheck/luajit directly.
+LUA_PATH = "{{config_root}}/?.lua;{{config_root}}/?/init.lua;{{config_root}}/lua/?.lua;{{config_root}}/lua/?/init.lua;{{config_root}}/.luarocks/share/lua/5.1/?.lua;{{config_root}}/.luarocks/share/lua/5.1/?/init.lua;;"
+LUA_CPATH = "{{config_root}}/.luarocks/lib/lua/5.1/?.so;;"
+
+[tasks.setup]
+description = "Build the Lua test rocks (busted/luacheck/luacov) for LuaJIT into ./.luarocks"
+run = '''
+set -eu
+if [ -x .luarocks/bin/busted ] && [ -x .luarocks/bin/luacheck ] && [ -x .luarocks/bin/luacov ]; then
+  echo ".luarocks already populated (run 'rm -rf .luarocks && mise run setup' to rebuild)"
+  exit 0
+fi
+LUAJIT_PREFIX="$(mise where luajit)"
+TREE="$PWD/.luarocks"
+echo "Building Lua test rocks for LuaJIT into $TREE ..."
+# Pinned to match what the former Nix flake provided (nixpkgs luajitPackages).
+for rock in "busted 2.2.0" "luacheck 1.2.0" "luacov 0.16.0"; do
+  ok=0
+  for attempt in 1 2 3; do
+    # shellcheck disable=SC2086
+    if luarocks --lua-dir "$LUAJIT_PREFIX" --lua-version 5.1 install --tree "$TREE" $rock; then
+      ok=1
+      break
+    fi
+    echo ">> luarocks install '$rock' failed (attempt $attempt/3)" >&2
+    # Back off before retrying so a transient luarocks.org/DNS blip can clear.
+    if [ "$attempt" -lt 3 ]; then sleep $((attempt * 3)); fi
+  done
+  [ "$ok" = 1 ] || { echo "ERROR: could not install $rock" >&2; exit 1; }
+done
+'''
+
+[tasks.check]
+description = "Check Lua syntax and run luacheck"
+depends = ["setup"]
+run = '''
+echo "Checking Lua files for syntax errors..."
+# Pipe into xargs so a failed loadfile propagates a non-zero exit on BSD find
+# (macOS) too — `find -exec ... \;` swallows the child's status there.
+find lua -name "*.lua" -type f -print0 | xargs -0 -I{} luajit -e "assert(loadfile('{}'))"
+echo "Running luacheck..."
+luacheck lua/ tests/ --no-unused-args --no-max-line-length
+'''
+
+[tasks.test]
+description = "Run the test suite with coverage"
+depends = ["setup"]
+run = '''
+echo "Running all tests..."
+TEST_FILES=$(find tests -type f -name "*_test.lua" -o -name "*_spec.lua" | sort)
+echo "Found test files:"
+echo "$TEST_FILES"
+if [ -n "$TEST_FILES" ]; then
+  busted --coverage -v $TEST_FILES
+else
+  echo "No test files found"
+fi
+'''
+
+[tasks.format]
+description = "Format the whole tree with treefmt"
+run = "treefmt"
+
+[tasks.format-check]
+description = "Verify formatting without writing (used in CI)"
+run = "treefmt --ci"
+
+[tasks.reviewfix]
+description = "Run reviewfixer against PR review findings (see reviewfixer.yaml)"
+# Scoped tool: only provisioned when this task runs, so `mise install`/CI skip
+# the beta Go binary. reviewfixer also needs node/npx for its ACP adapter, which
+# the top-level `node` tool already provides. Pass subcommands through, e.g.
+# `mise run reviewfix -- validate` or `mise run reviewfix -- run`.
+tools = { "github:ThomasK33/reviewfixer" = "0.1.0-beta.0" }
+run = 'reviewfixer --config ./reviewfixer.yaml'
+
+[tasks.clean]
+description = "Remove generated coverage files"
+run = '''
+rm -f luacov.report.out luacov.stats.out
+rm -f tests/lcov.info
+'''
+
+[tasks.all]
+description = "Format, lint, and test (full validation)"
+run = "mise run format && mise run check && mise run test"
diff --git a/reviewfixer.yaml b/reviewfixer.yaml
index 1812f125..b585a58b 100644
--- a/reviewfixer.yaml
+++ b/reviewfixer.yaml
@@ -3,17 +3,21 @@
 # reviewfixer automatically addresses PR review findings using an AI agent.
 #
 # Prerequisites:
-# - Use the project's Nix devShell (`nix develop` or `direnv allow`) which
-#   already includes `reviewfixer`; this is the primary dev path here, or
-# - `reviewfixer` CLI installed (`go install github.com/ThomasK33/reviewfixer@v0.1.0-beta.0`,
-#   or download a binary from https://github.com/ThomasK33/reviewfixer/releases)
-# - `node` and `npm`/`npx` available on PATH (for the ACP adapter below)
 # - `ANTHROPIC_API_KEY` exported in the shell that launches reviewfixer
+# - The `reviewfix` mise task provisions `reviewfixer` on demand (and `node`,
+#   already a top-level tool, supplies the npx-based ACP adapter below). It is
+#   intentionally NOT a global mise tool, so `mise install`/CI skip the beta
+#   binary. Run it via the task — see Usage. Alternatively, install the CLI
+#   yourself (`go install github.com/ThomasK33/reviewfixer@v0.1.0-beta.0`, or a
+#   binary from https://github.com/ThomasK33/reviewfixer/releases).
 #
-# Usage:
-#   reviewfixer validate --config ./reviewfixer.yaml
+# Usage (preferred — the task scopes the reviewfixer binary):
+#   mise run reviewfix                 # reviewfixer --config ./reviewfixer.yaml
+#   mise run reviewfix -- validate     # pass subcommands/flags after `--`
+#   mise run reviewfix -- run
+#
+# Or, with reviewfixer already on PATH:
 #   reviewfixer --config ./reviewfixer.yaml
-#   reviewfixer run --config ./reviewfixer.yaml
 #
 # If you install the adapter globally instead of using `npx`, you can replace:
 #   command: npx
diff --git a/scripts/run_integration_tests_individually.sh b/scripts/run_integration_tests_individually.sh
index a0b70b70..417e0607 100755
--- a/scripts/run_integration_tests_individually.sh
+++ b/scripts/run_integration_tests_individually.sh
@@ -4,6 +4,8 @@
 # Each test file is run separately with test_file
 
 set -e
+# pipefail: don't let `tee` mask a failing nvim in the pipe below
+set -o pipefail
 
 echo "=== Running Integration Tests Individually ==="
 
@@ -26,8 +28,8 @@ run_test_file() {
   local temp_output
   temp_output=$(mktemp)
 
-  # Run the test with timeout
-  if timeout 30s nix develop .#ci -c nvim --headless -u tests/minimal_init.lua \
+  # Run the test with timeout (nvim from PATH: action-setup-vim in CI, mise locally)
+  if timeout 30s nvim --headless -u tests/minimal_init.lua \
     -c "lua require('plenary.test_harness').test_file('$test_file', {minimal_init = 'tests/minimal_init.lua'})" \
     2>&1 | tee "$temp_output"; then
     EXIT_CODE=0
diff --git a/treefmt.toml b/treefmt.toml
new file mode 100644
index 00000000..3c04002b
--- /dev/null
+++ b/treefmt.toml
@@ -0,0 +1,56 @@
+# treefmt configuration — replaces the former Nix flake `nix fmt` (treefmt-nix).
+#
+# Run via `mise run format` (treefmt) or `mise run format-check` (treefmt --ci).
+# Every formatter/linter referenced here is provisioned by mise (see mise.toml).
+# treefmt's git walker already skips git-ignored paths; these also guard `--walk filesystem`.
+excludes = [
+  ".luarocks/**",
+  ".direnv/**",
+]
+
+[formatter.stylua]
+command = "stylua"
+includes = ["*.lua"]
+
+[formatter.prettier]
+command = "prettier"
+options = ["--write"]
+includes = [
+  "*.css",
+  "*.html",
+  "*.js",
+  "*.json",
+  "*.json5",
+  "*.jsx",
+  "*.markdown",
+  "*.md",
+  "*.mdx",
+  "*.mjs",
+  "*.scss",
+  "*.ts",
+  "*.tsx",
+  "*.vue",
+  "*.yaml",
+  "*.yml",
+]
+# lazy.nvim lock files are auto-generated and reformatted by lazy on update.
+excludes = ["fixtures/*/lazy-lock.json"]
+
+[formatter.shfmt]
+command = "shfmt"
+options = ["-i", "2", "-w"]
+includes = ["*.sh"]
+
+[formatter.shellcheck]
+command = "shellcheck"
+options = ["--exclude=SC1091,SC2016"]
+includes = ["*.sh"]
+
+[formatter.actionlint]
+command = "actionlint"
+includes = [".github/workflows/*.yml", ".github/workflows/*.yaml"]
+
+[formatter.zizmor]
+command = "zizmor"
+options = ["--offline"]
+includes = [".github/workflows/*.yml", ".github/workflows/*.yaml"]