spec status: show spec dirs touched in last resync commit

Adds _commit_spec_dirs() which runs 'git diff-tree' on the resync commit
and extracts the unique top-level test/ subdirectory names, giving a
clear summary of what was actually synced.

Example output:
  🕐 Last resync commit: 36dffed resyncing specs 05-18-2026 (3 days ago)
     Specs touched: discovery_and_monitoring, load_balancer, server_selection_logging

In verbose mode, prior resync commits also show their touched dirs.
3 new tests added.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: aclark4life

src/dbx_python_cli/commands/spec.py

@@ -384,6 +384,27 @@ def _commit_relative_date(repo_path: Path, commit_sha: str) -> str:
     return result.stdout.strip() or "unknown"
 
 
+def _commit_spec_dirs(repo_path: Path, commit_sha: str) -> list[str]:
+    """Return sorted unique top-level test subdirectory names changed in a commit.
+
+    Runs ``git diff-tree`` on the commit and extracts the first path component
+    under ``test/``, giving the spec directory names that were actually modified.
+    """
+    result = subprocess.run(
+        ["git", "diff-tree", "--no-commit-id", "-r", "--name-only", commit_sha],
+        cwd=repo_path,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    dirs: set[str] = set()
+    for line in result.stdout.splitlines():
+        parts = line.strip().split("/")
+        if len(parts) >= 2 and parts[0] == "test":
+            dirs.add(parts[1])
+    return sorted(dirs)
+
+
 def _spec_is_stale(
     specs_source: Path,
     driver_test: Path,
@@ -505,9 +526,16 @@ def spec_status(
         sha = recent[0].split()[0]
         age = _commit_relative_date(driver_path, sha)
         typer.echo(f"  🕐 Last resync commit: {recent[0]} ({age})")
+        spec_dirs = _commit_spec_dirs(driver_path, sha)
+        if spec_dirs:
+            typer.echo(f"     Specs touched: {', '.join(spec_dirs)}")
         if verbose and len(recent) > 1:
             for c in recent[1:]:
-                typer.echo(f"              also: {c}")
+                c_sha = c.split()[0]
+                c_age = _commit_relative_date(driver_path, c_sha)
+                c_dirs = _commit_spec_dirs(driver_path, c_sha)
+                dirs_str = f" — {', '.join(c_dirs)}" if c_dirs else ""
+                typer.echo(f"              also: {c} ({c_age}){dirs_str}")
     else:
         typer.echo("  ⚠  No resync commit found on this branch.", err=True)
 

tests/test_spec_command.py

@@ -751,3 +751,62 @@ def test_spec_status_suggests_combined_command(tmp_path):
     assert result.exit_code == 0
     assert "dbx spec sync" in result.output
     assert "To sync all stale specs at once" in result.output
+
+
+def test_commit_spec_dirs(tmp_path):
+    """_commit_spec_dirs extracts unique test subdirs from a real git commit."""
+    from dbx_python_cli.commands.spec import _commit_spec_dirs
+    from unittest.mock import patch, MagicMock
+
+    mock_result = MagicMock()
+    mock_result.stdout = (
+        "test/crud/foo.json\n"
+        "test/crud/bar.json\n"
+        "test/sessions/baz.json\n"
+        ".evergreen/resync-specs.sh\n"  # non-test file should be ignored
+        "test/auth/qux.json\n"
+    )
+
+    with patch("subprocess.run", return_value=mock_result):
+        dirs = _commit_spec_dirs(tmp_path, "abc1234")
+
+    assert dirs == ["auth", "crud", "sessions"]
+
+
+def test_commit_spec_dirs_no_test_files(tmp_path):
+    from dbx_python_cli.commands.spec import _commit_spec_dirs
+    from unittest.mock import patch, MagicMock
+
+    mock_result = MagicMock()
+    mock_result.stdout = ".evergreen/resync-specs.sh\n"
+
+    with patch("subprocess.run", return_value=mock_result):
+        dirs = _commit_spec_dirs(tmp_path, "abc1234")
+
+    assert dirs == []
+
+
+def test_spec_status_shows_specs_touched(tmp_path):
+    _, cfg = _make_status_repos(tmp_path, content_same=True)
+    with (
+        patch("dbx_python_cli.utils.repo.get_config_path", return_value=cfg),
+        patch(
+            "dbx_python_cli.commands.spec._get_current_branch",
+            return_value="spec-resync-test",
+        ),
+        patch(
+            "dbx_python_cli.commands.spec._find_recent_resync_commits",
+            return_value=["abc1234 resyncing specs 05-18-2026"],
+        ),
+        patch(
+            "dbx_python_cli.commands.spec._commit_relative_date",
+            return_value="3 days ago",
+        ),
+        patch(
+            "dbx_python_cli.commands.spec._commit_spec_dirs",
+            return_value=["auth", "crud", "sessions"],
+        ),
+    ):
+        result = runner.invoke(app, ["spec", "status"])
+    assert result.exit_code == 0
+    assert "Specs touched: auth, crud, sessions" in result.output