diff --git a/src/adapters/errorClassification.test.ts b/src/adapters/errorClassification.test.ts
index 4b93175..b680782 100644
--- a/src/adapters/errorClassification.test.ts
+++ b/src/adapters/errorClassification.test.ts
@@ -52,6 +52,10 @@ describe('isInfraError (INT-2010)', () => {
     expect(isInfraError(new TypeError('fetch failed'))).toBe(true);
   });
 
+  it('recognises a git-tracker snapshot/diff failure as infra (INT-2521)', () => {
+    expect(isInfraError(new Error('git-tracker: diff since snapshot failed: fatal: bad object'))).toBe(true);
+  });
+
   it('recognises local server capacity failures (5xx / loading / overloaded) (INT-2520)', () => {
     expect(isInfraError(new Error('Local API error (503): model is loading'))).toBe(true);
     expect(isInfraError(new Error('Local API error (502): bad gateway'))).toBe(true);
diff --git a/src/adapters/errorClassification.ts b/src/adapters/errorClassification.ts
index 4603027..83bd839 100644
--- a/src/adapters/errorClassification.ts
+++ b/src/adapters/errorClassification.ts
@@ -33,6 +33,7 @@ const INFRA_ERROR_PATTERNS = [
   'enotfound',
   'socket hang up',
   'network error',
+  'git-tracker:', // git snapshot/diff failed mid-run — infra, not a task verdict (colon-anchored to avoid prose) (INT-2521)
   'fetch failed', // undici: the real code hides in error.cause.code (checked below)
   'terminated', // undici mid-stream socket drop
   'unauthorized',
diff --git a/src/support/gitTracker.test.ts b/src/support/gitTracker.test.ts
index ffb2e9e..be0ebd0 100644
--- a/src/support/gitTracker.test.ts
+++ b/src/support/gitTracker.test.ts
@@ -32,6 +32,14 @@ describe('gitTracker', () => {
     await expect(getChangedFilesSinceSnapshot(repo, snapshot)).resolves.toContain('new-file.txt');
   });
 
+  it('throws a git-tracker error (not []) when git fails, so real edits are not dropped (INT-2521)', async () => {
+    // An invalid snapshot tree makes `git diff` fail. Returning [] would be
+    // indistinguishable from "no changes" and drop the worker's real work (false
+    // STUCK); it must throw with the git-tracker marker → classified infra_error.
+    await expect(getChangedFilesSinceSnapshot(repo, '0000000000000000000000000000000000000000'))
+      .rejects.toThrow(/git-tracker/);
+  });
+
   it('excludes pre-existing dirty files, reporting only changes after the snapshot (INT-2447)', async () => {
     // Repo is ALREADY dirty before the snapshot: an untracked file + a modified
     // tracked file. Previously the HEAD-only snapshot blamed the worker for both.
diff --git a/src/support/gitTracker.ts b/src/support/gitTracker.ts
index 955440a..3f8a77e 100644
--- a/src/support/gitTracker.ts
+++ b/src/support/gitTracker.ts
@@ -74,7 +74,10 @@ export async function takeSnapshot(projectPath: string): Promise<string> {
   try {
     return await writeWorktreeTree(projectPath);
   } catch (error) {
-    console.error('[GitTracker] takeSnapshot error:', error);
+    // Best-effort: proceed without the snapshot (the reviewer still judges the real
+    // diff, so an empty run can't silently pass). Warn LOUDLY so the disabled
+    // "did real work" guard is visible rather than looking like a clean run. (INT-2521)
+    console.warn('[GitTracker] takeSnapshot FAILED — "did real work" guard disabled for this run:', error);
     return '';
   }
 }
@@ -97,8 +100,13 @@ export async function getChangedFilesSinceSnapshot(
     const diff = await runGitCommand(projectPath, ['diff', '--name-only', snapshotTree, currentTree]);
     return diff.split('\n').filter(Boolean);
   } catch (error) {
+    // Do NOT return [] on a git failure — indistinguishable from "no changes", it
+    // would drop the worker's real edits (uncredited → false STUCK) or mask them.
+    // Throw with the 'git-tracker' marker so isInfraError routes it → infra_error
+    // (backoff retry), preserving the work for the next attempt. (INT-2521)
+    const msg = error instanceof Error ? error.message : String(error);
     console.error('[GitTracker] getChangedFilesSinceSnapshot error:', error);
-    return [];
+    throw new Error(`git-tracker: diff since snapshot failed: ${msg}`);
   }
 }
 
@@ -236,6 +244,7 @@ function runGitCommand(cwd: string, args: string[], env?: NodeJS.ProcessEnv): Pr
     let settled = false;
     const timer = setTimeout(() => {
       if (settled) return;
+      settled = true; // claim settlement before the late close/error handlers run
       proc.kill('SIGKILL');
       reject(new Error(`git ${args.join(' ')} timed out after ${GIT_CMD_TIMEOUT_MS}ms`));
     }, GIT_CMD_TIMEOUT_MS);