diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..115a1d6
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,46 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  check:
+    name: Check (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - name: Cache cargo registry and build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-
+
+      - name: Check formatting
+        run: cargo fmt --check
+
+      - name: Clippy
+        run: cargo clippy -- -D warnings
+
+      - name: Run tests
+        run: cargo test
diff --git a/Cargo.toml b/Cargo.toml
index 1da5e0d..c225f68 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,6 +4,12 @@ version = "0.1.0"
 edition = "2024"
 description = "CLI for arborist-metrics: cognitive/cyclomatic complexity and SLOC metrics"
 license = "MIT OR Apache-2.0"
+repository = "https://github.com/StrangeDaysTech/arborist-cli"
+homepage = "https://github.com/StrangeDaysTech/arborist-cli"
+readme = "README.md"
+keywords = ["complexity", "metrics", "cognitive", "cyclomatic", "cli"]
+categories = ["command-line-utilities", "development-tools"]
+exclude = [".devtrail/", ".github/", ".claude/", ".specify/", "specs/", "tests/fixtures/"]
 
 [dependencies]
 arborist-metrics = { version = "0.1", features = ["all"] }
diff --git a/tests/cli/directory.rs b/tests/cli/directory.rs
index 40910ef..42cada1 100644
--- a/tests/cli/directory.rs
+++ b/tests/cli/directory.rs
@@ -29,8 +29,14 @@ fn directory_gitignore_excludes() {
 
     assert!(output.status.success());
     let stdout = String::from_utf8(output.stdout).unwrap();
-    assert!(!stdout.contains("generated"), "gitignored file should be excluded");
-    assert!(stdout.contains("compute"), "non-ignored files should be included");
+    assert!(
+        !stdout.contains("generated"),
+        "gitignored file should be excluded"
+    );
+    assert!(
+        stdout.contains("compute"),
+        "non-ignored files should be included"
+    );
 }
 
 /// T029: verify `--languages rust` analyzes only .rs files, skips .py
@@ -44,7 +50,10 @@ fn directory_language_filter() {
     assert!(output.status.success());
     let stdout = String::from_utf8(output.stdout).unwrap();
     assert!(stdout.contains("Rust"), "should include Rust files");
-    assert!(!stdout.contains("Python"), "should not include Python files");
+    assert!(
+        !stdout.contains("Python"),
+        "should not include Python files"
+    );
 }
 
 /// T030: verify directory with no recognized files prints info and exits 0
@@ -56,7 +65,11 @@ fn directory_no_recognized_files() {
     // Let's just test that empty results are handled gracefully.
     // We'll use a path filter that excludes everything.
     cmd()
-        .args(["tests/fixtures/nested_project/", "--languages", "javascript"])
+        .args([
+            "tests/fixtures/nested_project/",
+            "--languages",
+            "javascript",
+        ])
         .assert()
         .success();
 }
diff --git a/tests/cli/filtering.rs b/tests/cli/filtering.rs
index a4f9bc4..8bea90e 100644
--- a/tests/cli/filtering.rs
+++ b/tests/cli/filtering.rs
@@ -31,8 +31,14 @@ fn threshold_exceeds_only() {
         .unwrap();
 
     let stdout = String::from_utf8(output.stdout).unwrap();
-    assert!(stdout.contains("complex_function"), "exceeding function should appear");
-    assert!(!stdout.contains("simple_function"), "non-exceeding function should be filtered");
+    assert!(
+        stdout.contains("complex_function"),
+        "exceeding function should appear"
+    );
+    assert!(
+        !stdout.contains("simple_function"),
+        "non-exceeding function should be filtered"
+    );
     assert!(
         !stdout.contains("moderate_function"),
         "non-exceeding function should be filtered"
@@ -68,11 +74,7 @@ fn no_methods_flag() {
 #[test]
 fn sort_cognitive_descending() {
     let output = cmd()
-        .args([
-            "tests/fixtures/nested_project/src/",
-            "--sort",
-            "cognitive",
-        ])
+        .args(["tests/fixtures/nested_project/src/", "--sort", "cognitive"])
         .output()
         .unwrap();
 
@@ -101,7 +103,11 @@ fn sort_name_ascending() {
     assert!(output.status.success());
     let stdout = String::from_utf8(output.stdout).unwrap();
     let compute_pos = stdout.find("compute").unwrap();
-    let main_pos = stdout.find(" main").unwrap_or_else(|| stdout.find("\nmain").unwrap_or_else(|| stdout.find("main").unwrap()));
+    let main_pos = stdout.find(" main").unwrap_or_else(|| {
+        stdout
+            .find("\nmain")
+            .unwrap_or_else(|| stdout.find("main").unwrap())
+    });
     let transform_pos = stdout.find("transform").unwrap();
     assert!(
         compute_pos < main_pos && main_pos < transform_pos,
diff --git a/tests/cli/output_formats.rs b/tests/cli/output_formats.rs
index 953913d..30227c8 100644
--- a/tests/cli/output_formats.rs
+++ b/tests/cli/output_formats.rs
@@ -73,7 +73,10 @@ fn csv_directory_multiple_rows() {
     let stdout = String::from_utf8(output.stdout).unwrap();
     let lines: Vec<&str> = stdout.lines().collect();
     // header + at least 3 functions (compute, transform, main)
-    assert!(lines.len() >= 4, "expected header + 3+ data rows, got {lines:?}");
+    assert!(
+        lines.len() >= 4,
+        "expected header + 3+ data rows, got {lines:?}"
+    );
 }
 
 /// T058: verify CSV with no-function file produces header only