fix(semgrep): capture end.line so multi-line findings use the full annotation range

.changeset/orange-foxes-shine.md

@@ -0,0 +1,13 @@
+---
+"layne": patch
+---
+
+fix(semgrep): capture end.line so multi-line findings span the full annotation range
+
+Semgrep emits both `start.line` and `end.line` in its JSON output, but
+the adapter only read `start.line` and left `startLine`/`endLine` unset.
+Every Semgrep annotation therefore collapsed to a single line even for
+rules that match multi-line constructs (e.g. multi-line function calls,
+object literals, imports). Added `end?: { line: number }` to the raw
+result interface and populate `startLine`/`endLine` in `toFinding`.
+Falls back to `startLine` when `end` is absent.

src/__tests__/adapters/semgrep.test.ts

@@ -238,4 +238,29 @@ describe('runSemgrep()', () => {
     const jsonIdx = args.indexOf('--json');
     expect(jsonIdx).toBe(scanIdx + 1);
   });
+
+  describe('startLine / endLine from Semgrep end.line', () => {
+    it('sets startLine and endLine from start.line and end.line on a single-line finding', async () => {
+      stubStdout(semgrepOutput([SEMGREP_RESULT]));
+      const [f] = await runSemgrep({ workspacePath: '/tmp/ws', changedFiles: CHANGED_FILES });
+      expect(f.startLine).toBe(10);
+      expect(f.endLine).toBe(10);
+    });
+
+    it('sets startLine and endLine from start.line and end.line on a multi-line finding', async () => {
+      const multiLine = { ...SEMGREP_RESULT, start: { line: 10, col: 1 }, end: { line: 14, col: 1 } };
+      stubStdout(semgrepOutput([multiLine]));
+      const [f] = await runSemgrep({ workspacePath: '/tmp/ws', changedFiles: CHANGED_FILES });
+      expect(f.startLine).toBe(10);
+      expect(f.endLine).toBe(14);
+    });
+
+    it('falls back endLine to startLine when end is missing from Semgrep output', async () => {
+      const noEnd = { check_id: SEMGREP_RESULT.check_id, path: SEMGREP_RESULT.path, start: { line: 7 }, extra: SEMGREP_RESULT.extra };
+      stubStdout(semgrepOutput([noEnd]));
+      const [f] = await runSemgrep({ workspacePath: '/tmp/ws', changedFiles: CHANGED_FILES });
+      expect(f.startLine).toBe(7);
+      expect(f.endLine).toBe(7);
+    });
+  });
 });

src/adapters/semgrep.ts

@@ -59,6 +59,7 @@ interface SemgrepRawResult {
   check_id: string;
   path: string;
   start?: { line: number };
+  end?: { line: number };
   extra?: { severity?: string; message?: string };
 }
 
@@ -69,12 +70,16 @@ const SEVERITY_MAP: Record<string, Severity> = {
 };
 
 function toFinding(result: SemgrepRawResult, workspacePath: string): SemgrepFinding {
+  const startLine = result.start?.line ?? 1;
+  const endLine   = result.end?.line ?? startLine;
   return {
-    file:     stripPrefix(result.path, workspacePath),
-    line:     result.start?.line ?? 1,
-    severity: SEVERITY_MAP[result.extra?.severity ?? ''] ?? 'low',
-    message:  result.extra?.message ?? 'Semgrep finding',
-    ruleId:   result.check_id,
-    tool:     'semgrep',
+    file:      stripPrefix(result.path, workspacePath),
+    line:      startLine,
+    startLine,
+    endLine,
+    severity:  SEVERITY_MAP[result.extra?.severity ?? ''] ?? 'low',
+    message:   result.extra?.message ?? 'Semgrep finding',
+    ruleId:    result.check_id,
+    tool:      'semgrep',
   };
 }