fix(tui): @<name> fuzzy-matches filenames across the repo

Typing `@appChrome` in the composer should surface
`ui-tui/src/components/appChrome.tsx` without requiring the user to
first type the full directory path — matches the Cmd-P behaviour
users expect from modern editors.

The gateway's `complete.path` handler was doing a plain
`os.listdir(".")` + `startswith` prefix match, so basenames only
resolved inside the current working directory. This reworks it to:

- enumerate repo files via `git ls-files -z --cached --others
  --exclude-standard` (fast, honours `.gitignore`); fall back to a
  bounded `os.walk` that skips common vendor / build dirs when the
  working dir isn't a git repo. Results cached per-root with a 5s
  TTL so rapid keystrokes don't respawn git processes.
- rank basenames with a 5-tier scorer: exact → prefix → camelCase
  / word-boundary → substring → subsequence. Shorter basenames win
  ties; shorter rel paths break basename-length ties.
- only take the fuzzy branch when the query is bare (no `/`), is a
  context reference (`@...`), and isn't `@folder:` — path-ish
  queries and folder tags fall through to the existing
  directory-listing path so explicit navigation intent is
  preserved.

Completion rows now carry `display = basename`,
`meta = directory`, so the picker renders
`appChrome.tsx  ui-tui/src/components` on one row (basename bold,
directory dim) — the meta column was previously "dir" / "" and is
a more useful signal for fuzzy hits.

Reported by Ben Barclay during the TUI v2 blitz test.

tests/gateway/test_complete_path_at_filter.py

@@ -1,22 +1,28 @@
 """Regression tests for the TUI gateway's `complete.path` handler.
 
-Reported during the TUI v2 blitz retest: typing `@folder:` (and `@folder`
-with no colon yet) still surfaced files alongside directories in the
-TUI composer, because the gateway-side completion lives in
-`tui_gateway/server.py` and was never touched by the earlier fix to
-`hermes_cli/commands.py`.
+Reported during the TUI v2 blitz retest:
+  - typing `@folder:` (and `@folder` with no colon yet) surfaced files
+    alongside directories — the gateway-side completion lives in
+    `tui_gateway/server.py` and was never touched by the earlier fix to
+    `hermes_cli/commands.py`.
+  - typing `@appChrome` required the full `@ui-tui/src/components/app…`
+    path to find the file — users expect Cmd-P-style fuzzy basename
+    matching across the repo, not a strict directory prefix filter.
 
 Covers:
   - `@folder:` only yields directories
   - `@file:` only yields regular files
   - Bare `@folder` / `@file` (no colon) lists cwd directly
   - Explicit prefix is preserved in the completion text
+  - `@<name>` with no slash fuzzy-matches basenames anywhere in the tree
 """
 
 from __future__ import annotations
 
 from pathlib import Path
 
+import pytest
+
 from tui_gateway import server
 
 
@@ -33,6 +39,15 @@ def _items(word: str):
     return [(it["text"], it["display"], it.get("meta", "")) for it in resp["result"]["items"]]
 
 
+@pytest.fixture(autouse=True)
+def _reset_fuzzy_cache(monkeypatch):
+    # Each test walks a fresh tmp dir; clear the cached listing so prior
+    # roots can't leak through the TTL window.
+    server._fuzzy_cache.clear()
+    yield
+    server._fuzzy_cache.clear()
+
+
 def test_at_folder_colon_only_dirs(tmp_path, monkeypatch):
     monkeypatch.chdir(tmp_path)
     _fixture(tmp_path)
@@ -89,3 +104,130 @@ def test_bare_at_still_shows_static_refs(tmp_path, monkeypatch):
 
     for expected in ("@diff", "@staged", "@file:", "@folder:", "@url:", "@git:"):
         assert expected in texts, f"missing static ref {expected!r} in {texts!r}"
+
+
+# ── Fuzzy basename matching ──────────────────────────────────────────────
+# Users shouldn't have to know the full path — typing `@appChrome` should
+# find `ui-tui/src/components/appChrome.tsx`.
+
+
+def _nested_fixture(tmp_path: Path):
+    (tmp_path / "readme.md").write_text("x")
+    (tmp_path / ".env").write_text("x")
+    (tmp_path / "ui-tui/src/components").mkdir(parents=True)
+    (tmp_path / "ui-tui/src/components/appChrome.tsx").write_text("x")
+    (tmp_path / "ui-tui/src/components/appLayout.tsx").write_text("x")
+    (tmp_path / "ui-tui/src/components/thinking.tsx").write_text("x")
+    (tmp_path / "ui-tui/src/hooks").mkdir(parents=True)
+    (tmp_path / "ui-tui/src/hooks/useCompletion.ts").write_text("x")
+    (tmp_path / "tui_gateway").mkdir()
+    (tmp_path / "tui_gateway/server.py").write_text("x")
+
+
+def test_fuzzy_at_finds_file_without_directory_prefix(tmp_path, monkeypatch):
+    """`@appChrome` — with no slash — should surface the nested file."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    entries = _items("@appChrome")
+    texts = [t for t, _, _ in entries]
+
+    assert "@file:ui-tui/src/components/appChrome.tsx" in texts, texts
+
+    # Display is the basename, meta is the containing directory, so the
+    # picker can show `appChrome.tsx  ui-tui/src/components` on one row.
+    row = next(r for r in entries if r[0] == "@file:ui-tui/src/components/appChrome.tsx")
+    assert row[1] == "appChrome.tsx"
+    assert row[2] == "ui-tui/src/components"
+
+
+def test_fuzzy_ranks_exact_before_prefix_before_subseq(tmp_path, monkeypatch):
+    """Better matches sort before weaker matches regardless of path depth."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+    (tmp_path / "server.py").write_text("x")  # exact basename match at root
+
+    texts = [t for t, _, _ in _items("@server")]
+
+    # Exact `server.py` beats `tui_gateway/server.py` (prefix match) — both
+    # rank 1 on basename but exact basename wins on the sort key; shorter
+    # rel path breaks ties.
+    assert texts[0] == "@file:server.py", texts
+    assert "@file:tui_gateway/server.py" in texts
+
+
+def test_fuzzy_camelcase_word_boundary(tmp_path, monkeypatch):
+    """Mid-basename camelCase pieces match without substring scanning."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    texts = [t for t, _, _ in _items("@Chrome")]
+
+    # `Chrome` starts a camelCase word inside `appChrome.tsx`.
+    assert "@file:ui-tui/src/components/appChrome.tsx" in texts, texts
+
+
+def test_fuzzy_subsequence_catches_sparse_queries(tmp_path, monkeypatch):
+    """`@uCo` → `useCompletion.ts` via subsequence, last-resort tier."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    texts = [t for t, _, _ in _items("@uCo")]
+
+    assert "@file:ui-tui/src/hooks/useCompletion.ts" in texts, texts
+
+
+def test_fuzzy_at_file_prefix_preserved(tmp_path, monkeypatch):
+    """Explicit `@file:` prefix still wins the completion tag."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    texts = [t for t, _, _ in _items("@file:appChrome")]
+
+    assert "@file:ui-tui/src/components/appChrome.tsx" in texts, texts
+
+
+def test_fuzzy_skipped_when_path_has_slash(tmp_path, monkeypatch):
+    """Any `/` in the query = user is navigating; keep directory listing."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    texts = [t for t, _, _ in _items("@ui-tui/src/components/app")]
+
+    # Directory-listing mode prefixes with `@file:` / `@folder:` per entry.
+    # It should only surface direct children of the named dir — not the
+    # nested `useCompletion.ts`.
+    assert any("appChrome.tsx" in t for t in texts), texts
+    assert not any("useCompletion.ts" in t for t in texts), texts
+
+
+def test_fuzzy_skipped_when_folder_tag(tmp_path, monkeypatch):
+    """`@folder:<name>` still lists directories — fuzzy scanner only walks
+    files (git-tracked + untracked), so defer to the dir-listing path."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    texts = [t for t, _, _ in _items("@folder:ui")]
+
+    # Root has `ui-tui/` as a directory; the listing branch should surface it.
+    assert any(t.startswith("@folder:ui-tui") for t in texts), texts
+
+
+def test_fuzzy_hides_dotfiles_unless_asked(tmp_path, monkeypatch):
+    """`.env` doesn't leak into `@env` but does show for `@.env`."""
+    monkeypatch.chdir(tmp_path)
+    _nested_fixture(tmp_path)
+
+    assert not any(".env" in t for t, _, _ in _items("@env"))
+    assert any(t.endswith(".env") for t, _, _ in _items("@.env"))
+
+
+def test_fuzzy_caps_results(tmp_path, monkeypatch):
+    """The 30-item cap survives a big tree."""
+    monkeypatch.chdir(tmp_path)
+    for i in range(60):
+        (tmp_path / f"mod_{i:03d}.py").write_text("x")
+
+    items = _items("@mod")
+
+    assert len(items) == 30