feat(chunker): add Dart language support

README.md

@@ -158,14 +158,15 @@ judge rationales, and reproduce instructions.
 
 ## Supported languages
 
-Supports **11 language families** with semantic chunking (8 benchmarked):
+Supports **12 language families** with semantic chunking (9 benchmarked):
 
 | Language         | Parser      | Extensions                                | Benchmark status                              |
 | ---------------- | ----------- | ----------------------------------------- | --------------------------------------------- |
 | Go               | Native AST  | `.go`                                     | Benchmarked: -12% cost, Good quality          |
 | Python           | tree-sitter | `.py`                                     | Benchmarked: Perfect quality, -36% tokens     |
 | TypeScript / TSX | tree-sitter | `.ts`, `.tsx`                             | Benchmarked: -64% tokens, -33% time           |
 | JavaScript / JSX | tree-sitter | `.js`, `.jsx`, `.mjs`                     | Benchmarked: -66% tokens, -53% time           |
+| Dart             | tree-sitter | `.dart`                                   | Benchmarked: -76% cost, -82% tokens, -79% time |
 | Rust             | tree-sitter | `.rs`                                     | Benchmarked: -39% cost, -34% time             |
 | Ruby             | tree-sitter | `.rb`                                     | Benchmarked: -24% cost, -11% time             |
 | PHP              | tree-sitter | `.php`                                    | Benchmarked: -59% tokens, -34% time           |
@@ -175,7 +176,7 @@ Supports **11 language families** with semantic chunking (8 benchmarked):
 
 Go uses the native Go AST parser for the most precise chunks. All other
 languages use tree-sitter grammars. See [docs/BENCHMARKS.md](docs/BENCHMARKS.md)
-for all 8 per-language benchmark deep dives.
+for all 9 per-language benchmark deep dives.
 
 ## Configuration
 

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-judge.json

@@ -0,0 +1 @@
+{"rating":"Good","files_correct":true,"logic_equivalent":false}

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-judge.md

@@ -0,0 +1,3 @@
+## Rating: Good
+
+The candidate patch correctly fixes the core RFC violation by removing the `content-length: '0'` override, allowing the original content-length to pass through unchanged, and only strips the body. However, it uses a different approach than the gold patch: it keeps the `createMiddleware` structure (which has known issues with async handlers) rather than converting to a proper `Handler`-wrapping function. The candidate also adds a standalone test instead of enhancing the existing HEAD tests, but the test itself correctly validates both the content-length preservation and empty body requirements.

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-metrics.json

@@ -0,0 +1,8 @@
+{
+  "cost_usd": 0.6341989499999998,
+  "duration_ms": 246069,
+  "input_tokens": 439,
+  "cache_read": 4126087,
+  "cache_created": 91777,
+  "output_tokens": 21286
+}

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-patch.diff

@@ -0,0 +1,50 @@
+diff --git a/pkgs/shelf_router/lib/src/router.dart b/pkgs/shelf_router/lib/src/router.dart
+index 720d3c3..8613f01 100644
+--- a/pkgs/shelf_router/lib/src/router.dart
++++ b/pkgs/shelf_router/lib/src/router.dart
+@@ -58,11 +58,12 @@ extension RouterParams on Request {
+   }
+ }
+
+-/// Middleware to remove body from request.
++/// Middleware to remove body from HEAD requests.
++///
++/// Per RFC 9110 Section 9.3.2, HEAD and GET responses should be identical
++/// except for the body. The content-length header should reflect the size of
++/// the body that WOULD have been returned by a GET request.
+ final _removeBody = createMiddleware(responseHandler: (r) {
+-  if (r.headers.containsKey('content-length')) {
+-    r = r.change(headers: {'content-length': '0'});
+-  }
+   return r.change(body: <int>[]);
+ });
+
+diff --git a/pkgs/shelf_router/test/router_test.dart b/pkgs/shelf_router/test/router_test.dart
+index fdffa51..cb19c9c 100644
+--- a/pkgs/shelf_router/test/router_test.dart
++++ b/pkgs/shelf_router/test/router_test.dart
+@@ -204,4 +204,24 @@ void main() {
+     final b2 = await Router.routeNotFound.readAsString();
+     expect(b2, b1);
+   });
++
++  test('HEAD request should preserve content-length header per RFC 9110', () async {
++    var app = Router();
++
++    app.get('/hello', (Request request) {
++      // Explicitly set content-length header
++      return Response.ok('hello-world',
++          headers: {'content-length': '11'});
++    });
++
++    // Create a request with HEAD method
++    final headRequest = Request('HEAD', Uri.parse('http://localhost/hello'));
++    final headResponse = await app(headRequest);
++
++    // Per RFC 9110 Section 9.3.2, the content-length should be preserved
++    expect(headResponse.headers['content-length'], '11');
++
++    // Verify that the body is empty
++    expect(await headResponse.readAsString(), isEmpty);
++  });
+ }

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-stderr.log

@@ -0,0 +1 @@
+SessionEnd hook [_R="${CLAUDE_PLUGIN_ROOT}"; [ -z "$_R" ] && _R="$HOME/.claude/plugins/marketplaces/thedotmack/plugin"; node "$_R/scripts/bun-runner.js" "$_R/scripts/worker-service.cjs" hook claude-code session-complete] failed: Hook cancelled

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-baseline-tests.txt

@@ -0,0 +1 @@
+00:00 +0: loading test/router_test.dart                                                                                                                                                                00:00 +0: get sync/async handler                                                                                                                                                                       00:00 +1: get sync/async handler                                                                                                                                                                       00:00 +1: params                                                                                                                                                                                       00:00 +2: params                                                                                                                                                                                       00:00 +2: params by arguments                                                                                                                                                                          00:00 +3: params by arguments                                                                                                                                                                          00:00 +3: mount(Router)                                                                                                                                                                                00:00 +4: mount(Router)                                                                                                                                                                                00:00 +4: mount(Handler) with middleware                                                                                                                                                               00:00 +5: mount(Handler) with middleware                                                                                                                                                               00:00 +5: mount(Router) does not require a trailing slash                                                                                                                                              00:00 +6: mount(Router) does not require a trailing slash                                                                                                                                              00:00 +6: responds with 404 if no handler matches                                                                                                                                                      00:00 +7: responds with 404 if no handler matches                                                                                                                                                      00:00 +7: can invoke custom handler if no route matches                                                                                                                                                00:00 +8: can invoke custom handler if no route matches                                                                                                                                                00:00 +8: can call Router.routeNotFound.read multiple times                                                                                                                                            00:00 +9: can call Router.routeNotFound.read multiple times                                                                                                                                            00:00 +9: HEAD request should preserve content-length header per RFC 9110                                                                                                                              00:00 +10: HEAD request should preserve content-length header per RFC 9110                                                                                                                             00:00 +10: All tests passed!                                                                                                                                                                           

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-with-lumen-judge.json

@@ -0,0 +1 @@
+{"rating":"Good","files_correct":false,"logic_equivalent":false}

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-with-lumen-judge.md

@@ -0,0 +1,3 @@
+## Rating: Good
+
+The candidate patch correctly removes the `content-length: '0'` override, which is the core RFC violation. However, it only modifies `router.dart` and doesn't update the tests to verify the content-length behavior, whereas the gold patch also refactors `_removeBody` from `createMiddleware` to a proper `Handler` wrapper (which handles both sync and async responses correctly) and adds comprehensive test assertions. The candidate's approach of keeping `createMiddleware` while just removing the bad line is a simpler but still valid fix that preserves correct content-length headers.

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-with-lumen-metrics.json

@@ -0,0 +1,8 @@
+{
+  "cost_usd": 0.15332435000000003,
+  "duration_ms": 50922,
+  "input_tokens": 126,
+  "cache_read": 663146,
+  "cache_created": 54059,
+  "output_tokens": 3862
+}

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-with-lumen-patch.diff

@@ -0,0 +1,14 @@
+diff --git a/pkgs/shelf_router/lib/src/router.dart b/pkgs/shelf_router/lib/src/router.dart
+index 720d3c3..d68627a 100644
+--- a/pkgs/shelf_router/lib/src/router.dart
++++ b/pkgs/shelf_router/lib/src/router.dart
+@@ -60,9 +60,6 @@ extension RouterParams on Request {
+
+ /// Middleware to remove body from request.
+ final _removeBody = createMiddleware(responseHandler: (r) {
+-  if (r.headers.containsKey('content-length')) {
+-    r = r.change(headers: {'content-length': '0'});
+-  }
+   return r.change(body: <int>[]);
+ });
+

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/dart-hard-with-lumen-tests.txt

@@ -0,0 +1 @@
+00:00 +0: loading test/router_test.dart                                                                                                                                                                00:00 +0: get sync/async handler                                                                                                                                                                       00:00 +1: get sync/async handler                                                                                                                                                                       00:00 +1: params                                                                                                                                                                                       00:00 +2: params                                                                                                                                                                                       00:00 +2: params by arguments                                                                                                                                                                          00:00 +3: params by arguments                                                                                                                                                                          00:00 +3: mount(Router)                                                                                                                                                                                00:00 +4: mount(Router)                                                                                                                                                                                00:00 +4: mount(Handler) with middleware                                                                                                                                                               00:00 +5: mount(Handler) with middleware                                                                                                                                                               00:00 +5: mount(Router) does not require a trailing slash                                                                                                                                              00:00 +6: mount(Router) does not require a trailing slash                                                                                                                                              00:00 +6: responds with 404 if no handler matches                                                                                                                                                      00:00 +7: responds with 404 if no handler matches                                                                                                                                                      00:00 +7: can invoke custom handler if no route matches                                                                                                                                                00:00 +8: can invoke custom handler if no route matches                                                                                                                                                00:00 +8: can call Router.routeNotFound.read multiple times                                                                                                                                            00:00 +9: can call Router.routeNotFound.read multiple times                                                                                                                                            00:00 +9: All tests passed!                                                                                                                                                                            

bench-results/swe-20260327-190213-ollama-jina-embeddings-v2-base-code/detail-report.md

@@ -0,0 +1,110 @@
+# SWE-Bench Detail Report
+
+Generated: 2026-03-27 18:08 UTC
+
+---
+
+## dart-hard [dart]
+
+**Issue:** shelf_router should NOT modify the content-length per RFC
+
+> The shelf_router `_removeBody` middleware incorrectly sets content-length to 0 for HEAD requests.
+> 
+> Per RFC 9110 Section 9.3.2, HEAD and GET should be identical except for the lack of body content. The content-length header should reflect the size of the body that WOULD have been returned by a GET request, not 0.
+> 
+> Currently, when a HEAD request is made, the router's _removeBody middleware replaces the content-length with '0', which violates the RFC. The middleware should only strip the body content while preserving the original content-length header.
+> 
+> To reproduce:
+> 1. Create a Router with a handler that returns a response with a body
+> 2. Send a HEAD request to that route
+> 3. Observe that content-length is set to 0 instead of the actual body length
+> 
+> Expected: content-length should match what GET would return (e.g., 11 for 'hello-world')
+> Actual: content-length is set to 0
+
+### Metrics
+
+| Scenario | Duration | Input Tok | Cache Read | Output Tok | Cost |
+|----------|----------|-----------|------------|------------|------|
+| **baseline** | 246.1s | 439 | 4126087 | 21286 | $0.6342 |
+| **with-lumen** | 50.9s | 126 | 663146 | 3862 | $0.1533 |
+
+### baseline
+
+**Rating: Good**
+
+```diff
+diff --git a/pkgs/shelf_router/lib/src/router.dart b/pkgs/shelf_router/lib/src/router.dart
+index 720d3c3..8613f01 100644
+--- a/pkgs/shelf_router/lib/src/router.dart
++++ b/pkgs/shelf_router/lib/src/router.dart
+@@ -58,11 +58,12 @@ extension RouterParams on Request {
+   }
+ }
+
+-/// Middleware to remove body from request.
++/// Middleware to remove body from HEAD requests.
++///
++/// Per RFC 9110 Section 9.3.2, HEAD and GET responses should be identical
++/// except for the body. The content-length header should reflect the size of
++/// the body that WOULD have been returned by a GET request.
+ final _removeBody = createMiddleware(responseHandler: (r) {
+-  if (r.headers.containsKey('content-length')) {
+-    r = r.change(headers: {'content-length': '0'});
+-  }
+   return r.change(body: <int>[]);
+ });
+
+diff --git a/pkgs/shelf_router/test/router_test.dart b/pkgs/shelf_router/test/router_test.dart
+index fdffa51..cb19c9c 100644
+--- a/pkgs/shelf_router/test/router_test.dart
++++ b/pkgs/shelf_router/test/router_test.dart
+@@ -204,4 +204,24 @@ void main() {
+     final b2 = await Router.routeNotFound.readAsString();
+     expect(b2, b1);
+   });
++
++  test('HEAD request should preserve content-length header per RFC 9110', () async {
++    var app = Router();
++
++    app.get('/hello', (Request request) {
++      // Explicitly set content-length header
++      return Response.ok('hello-world',
++          headers: {'content-length': '11'});
++    });
++
++    // Create a request with HEAD method
++    final headRequest = Request('HEAD', Uri.parse('http://localhost/hello'));
++    final headResponse = await app(headRequest);
++
++    // Per RFC 9110 Section 9.3.2, the content-length should be preserved
++    expect(headResponse.headers['content-length'], '11');
++
++    // Verify that the body is empty
++    expect(await headResponse.readAsString(), isEmpty);
++  });
+ }
+```
+
+### with-lumen
+
+**Rating: Good**
+
+```diff
+diff --git a/pkgs/shelf_router/lib/src/router.dart b/pkgs/shelf_router/lib/src/router.dart
+index 720d3c3..d68627a 100644
+--- a/pkgs/shelf_router/lib/src/router.dart
++++ b/pkgs/shelf_router/lib/src/router.dart
+@@ -60,9 +60,6 @@ extension RouterParams on Request {
+
+ /// Middleware to remove body from request.
+ final _removeBody = createMiddleware(responseHandler: (r) {
+-  if (r.headers.containsKey('content-length')) {
+-    r = r.change(headers: {'content-length': '0'});
+-  }
+   return r.change(body: <int>[]);
+ });
+
+```
+
+