feat: Git Reset support

src/simulation.test.ts

@@ -132,6 +132,44 @@ describe('git state simulation scenarios', () => {
     expect(committed.changes[0]?.current).toBeUndefined();
   });
 
+  it('unstages modified file on mixed reset', async () => {
+    const sim = await trackSimulationWithTrackedFile('reset-mixed.ts', 'v1\n');
+
+    await sim.write('reset-mixed.ts', 'v2\n', { label: 'edit before reset' });
+    const staged = await sim.gitAdd('reset-mixed.ts', { label: 'stage before reset' });
+    expect(staged.tree).toContain('[M staged]');
+
+    const reset = await sim.gitReset('mixed', { label: 'mixed reset' });
+    expect(reset.changes).toHaveLength(1);
+    expect(reset.tree).toContain('[M unstaged]');
+    expect(reset.changes[0]).toMatchObject({
+      path: 'reset-mixed.ts',
+      previous: { staged: true, unstaged: false },
+      current: {
+        path: 'reset-mixed.ts',
+        status: 'modified',
+        staged: false,
+        unstaged: true,
+      },
+    });
+  });
+
+  it('clears dirty tracked state on hard reset', async () => {
+    const sim = await trackSimulationWithTrackedFile('reset-hard.ts', 'v1\n');
+
+    await sim.write('reset-hard.ts', 'v2\n', { label: 'edit before hard reset' });
+    await sim.gitAdd('reset-hard.ts', { label: 'stage before hard reset' });
+
+    const reset = await sim.gitReset('hard', { label: 'hard reset' });
+    expect(reset.changes).toHaveLength(1);
+    expect(reset.tree).not.toContain('[M');
+    expect(reset.changes[0]).toMatchObject({
+      path: 'reset-hard.ts',
+      current: undefined,
+    });
+    expect(sim.getState()).toEqual([]);
+  });
+
   it('does not emit extra events for unchanged filesystem writes', async () => {
     const sim = await trackSimulationWithTrackedFile('stable.ts', 'same\n');
 

src/watcher.test.ts

@@ -43,6 +43,14 @@ async function simpleGitAdd(repoPath: string, filePath: string): Promise<void> {
   await simpleGit(repoPath).add(filePath);
 }
 
+async function simpleGitReset(
+  repoPath: string,
+  mode: 'soft' | 'mixed' | 'hard',
+): Promise<void> {
+  const { simpleGit } = await import('simple-git');
+  await simpleGit(repoPath).reset([`--${mode}`]);
+}
+
 afterEach(async () => {
   await Promise.all(
     tempRepos.splice(0).map((repo) => fs.rm(repo, { recursive: true, force: true })),
@@ -144,6 +152,45 @@ describe('createGitStateWatcher', () => {
     await watcher.close();
   });
 
+  it('emits when git metadata changes on mixed reset', async () => {
+    const repo = await trackRepo();
+    await writeAndAdd(repo, 'tracked.ts', 'v1\n');
+    await simpleGitCommit(repo, 'initial');
+    await fs.writeFile(path.join(repo, 'tracked.ts'), 'v2\n', 'utf8');
+
+    const watcher = await createGitStateWatcher(repo, { debounceMs: 75 });
+    expect(watcher.getFileState('tracked.ts')).toMatchObject({
+      path: 'tracked.ts',
+      status: 'modified',
+      staged: false,
+      unstaged: true,
+    });
+
+    const stagedChangesPromise = waitForChanges(watcher);
+    await simpleGitAdd(repo, 'tracked.ts');
+    const stagedChanges = await stagedChangesPromise;
+
+    expect(stagedChanges).toHaveLength(1);
+    expect(stagedChanges[0]).toMatchObject({
+      path: 'tracked.ts',
+      previous: { staged: false, unstaged: true },
+      current: { status: 'modified', staged: true, unstaged: false },
+    });
+
+    const resetChangesPromise = waitForChanges(watcher);
+    await simpleGitReset(repo, 'mixed');
+    const resetChanges = await resetChangesPromise;
+
+    expect(resetChanges).toHaveLength(1);
+    expect(resetChanges[0]).toMatchObject({
+      path: 'tracked.ts',
+      previous: { staged: true, unstaged: false },
+      current: { status: 'modified', staged: false, unstaged: true },
+    });
+
+    await watcher.close();
+  });
+
   it('does not emit when filesystem noise leaves git state unchanged', async () => {
     const repo = await trackRepo();
     await writeAndAdd(repo, 'stable.ts', 'same\n');