refactor(tui): simplify TUI build logic, remove stale staleness checks

The old mtime-tracking staleness machinery (_tui_build_needed,
_hermes_ink_bundle_stale, _find_bundled_tui) tried to avoid rebuilding
by comparing source timestamps to dist/entry.js. This was fragile and
added ~100 lines of code. Replace with three clear paths:

1. HERMES_TUI_DIR set (prebuilt/nix): just node dist/entry.js, no build
2. --dev mode: tsx src/entry.tsx, no build, hot reload
3. Normal: always npm run build (esbuild is ~1s, correctness > caching)

Also error when HERMES_TUI_DIR is set with --dev (footgun: prebuilt
bundle has no source code to hot-reload).

hermes_cli/main.py

@@ -967,66 +967,6 @@ def _tui_need_npm_install(root: Path) -> bool:
     return False
 
 
-def _find_bundled_tui(tui_dir: Path) -> Optional[Path]:
-    """Directory whose dist/entry.js we should run: HERMES_TUI_DIR first, else repo ui-tui."""
-    env = os.environ.get("HERMES_TUI_DIR")
-    if env:
-        p = Path(env)
-        if (p / "dist" / "entry.js").exists() and not _tui_need_npm_install(p):
-            return p
-    if (tui_dir / "dist" / "entry.js").exists() and not _tui_need_npm_install(tui_dir):
-        return tui_dir
-    return None
-
-
-def _tui_build_needed(tui_dir: Path) -> bool:
-    # esbuild bundles @hermes/ink + source directly into dist/entry.js;
-    # the old ink-bundle.js check only fires when entry.js hasn't been
-    # produced yet (a dev checkout that hasn't been built at all). Once
-    # entry.js exists, the mtime walk below covers all source trees.
-    entry = tui_dir / "dist" / "entry.js"
-    if not entry.exists():
-        # Nothing built yet — signal that a build is needed.
-        return True
-    dist_m = entry.stat().st_mtime
-    skip = frozenset({"node_modules", "dist"})
-    for dirpath, dirnames, filenames in os.walk(tui_dir, topdown=True):
-        dirnames[:] = [d for d in dirnames if d not in skip]
-        for fn in filenames:
-            if fn.endswith((".ts", ".tsx")):
-                if os.path.getmtime(os.path.join(dirpath, fn)) > dist_m:
-                    return True
-    for meta in (
-        "package.json",
-        "package-lock.json",
-        "tsconfig.json",
-        "tsconfig.build.json",
-    ):
-        mp = tui_dir / meta
-        if mp.exists() and mp.stat().st_mtime > dist_m:
-            return True
-    return False
-
-
-def _hermes_ink_bundle_stale(tui_dir: Path) -> bool:
-    ink_root = tui_dir / "packages" / "hermes-ink"
-    bundle = ink_root / "dist" / "ink-bundle.js"
-    if not bundle.exists():
-        return True
-    bm = bundle.stat().st_mtime
-    skip = frozenset({"node_modules", "dist"})
-    for dirpath, dirnames, filenames in os.walk(ink_root, topdown=True):
-        dirnames[:] = [d for d in dirnames if d not in skip]
-        for fn in filenames:
-            if fn.endswith((".ts", ".tsx")):
-                if os.path.getmtime(os.path.join(dirpath, fn)) > bm:
-                    return True
-    mp = ink_root / "package.json"
-    if mp.exists() and mp.stat().st_mtime > bm:
-        return True
-    return False
-
-
 def _ensure_tui_node() -> None:
     """Make sure `node` + `npm` are on PATH for the TUI.
 
@@ -1085,7 +1025,7 @@ def _ensure_tui_node() -> None:
 
 
 def _make_tui_argv(tui_dir: Path, tui_dev: bool) -> tuple[list[str], Path]:
-    """TUI: --dev → tsx src; else node dist (HERMES_TUI_DIR or ui-tui, build when stale)."""
+    """TUI: --dev → tsx src; else node dist (HERMES_TUI_DIR prebuilt or esbuild)."""
     _ensure_tui_node()
 
     def _node_bin(bin: str) -> str:
@@ -1099,23 +1039,31 @@ def _make_tui_argv(tui_dir: Path, tui_dev: bool) -> tuple[list[str], Path]:
             sys.exit(1)
         return path
 
-    # pre-built dist + node_modules (nix / full HERMES_TUI_DIR) skips npm.
+    # Footgun: --dev against a prebuilt bundle that has no source/node_modules.
+    ext_dir = os.environ.get("HERMES_TUI_DIR")
+    if tui_dev and ext_dir:
+        print(
+            f"Error: --dev is incompatible with HERMES_TUI_DIR={ext_dir}\n"
+            f"The prebuilt TUI has no source code to hot-reload.\n"
+            f"Unset HERMES_TUI_DIR (e.g. `unset HERMES_TUI_DIR`) to use --dev from a checkout.",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+    # 1. Prebuilt bundle (nix / packaged release): just run it.
     if not tui_dev:
-        ext_dir = os.environ.get("HERMES_TUI_DIR")
         if ext_dir:
             p = Path(ext_dir)
-            if (p / "dist" / "entry.js").exists() and not _tui_need_npm_install(p):
+            if (p / "dist" / "entry.js").is_file():
                 node = _node_bin("node")
                 return [node, str(p / "dist" / "entry.js")], p
 
-    npm = _node_bin("npm")
+    # 2. Normal flow: npm install if needed, always esbuild, then node dist/entry.js.
+    #    --dev flow: npm install if needed, then tsx src/entry.tsx (no build).
     if _tui_need_npm_install(tui_dir):
+        npm = _node_bin("npm")
         if not os.environ.get("HERMES_QUIET"):
             print("Installing TUI dependencies…")
-        # Capture stdout as well as stderr — some npm errors (notably EACCES on a
-        # root-owned node_modules in containers) are emitted on stdout, and a
-        # bare "npm install failed." with no preview defeats debugging.  We keep
-        # the failure-only print path so a successful install stays silent.
         result = subprocess.run(
             [npm, "install", "--silent", "--no-fund", "--no-audit", "--progress=false"],
             cwd=str(tui_dir),
@@ -1133,47 +1081,30 @@ def _make_tui_argv(tui_dir: Path, tui_dev: bool) -> tuple[list[str], Path]:
             sys.exit(1)
 
     if tui_dev:
-        if _hermes_ink_bundle_stale(tui_dir):
-            result = subprocess.run(
-                [npm, "run", "build", "--prefix", "packages/hermes-ink"],
-                cwd=str(tui_dir),
-                capture_output=True,
-                text=True,
-            )
-            if result.returncode != 0:
-                combined = f"{result.stdout or ''}{result.stderr or ''}".strip()
-                preview = "\n".join(combined.splitlines()[-30:])
-                print("@hermes/ink build failed.")
-                if preview:
-                    print(preview)
-                sys.exit(1)
         tsx = tui_dir / "node_modules" / ".bin" / "tsx"
         if tsx.exists():
             return [str(tsx), "src/entry.tsx"], tui_dir
+        npm = _node_bin("npm")
         return [npm, "start"], tui_dir
 
-    if _tui_build_needed(tui_dir):
+    # Always rebuild — esbuild is fast and this avoids staleness-edge-case bugs.
-        result = subprocess.run(
+    npm = _node_bin("npm")
-            [npm, "run", "build"],
+    result = subprocess.run(
-            cwd=str(tui_dir),
+        [npm, "run", "build"],
-            capture_output=True,
+        cwd=str(tui_dir),
-            text=True,
+        capture_output=True,
-        )
+        text=True,
-        if result.returncode != 0:
+    )
-            combined = f"{result.stdout or ''}{result.stderr or ''}".strip()
+    if result.returncode != 0:
-            preview = "\n".join(combined.splitlines()[-30:])
+        combined = f"{result.stdout or ''}{result.stderr or ''}".strip()
-            print("TUI build failed.")
+        preview = "\n".join(combined.splitlines()[-30:])
-            if preview:
+        print("TUI build failed.")
-                print(preview)
+        if preview:
-            sys.exit(1)
+            print(preview)
-
-    root = _find_bundled_tui(tui_dir)
-    if not root:
-        print("TUI build did not produce dist/entry.js")
         sys.exit(1)
 
     node = _node_bin("node")
-    return [node, str(root / "dist" / "entry.js")], root
+    return [node, str(tui_dir / "dist" / "entry.js")], tui_dir
 
 
 def _normalize_tui_toolsets(toolsets: object) -> list[str]:
@@ -5503,7 +5434,6 @@ def _gateway_prompt(prompt_text: str, default: str = "", timeout: float = 300.0)
 def _web_ui_build_needed(web_dir: Path) -> bool:
     """Return True if the web UI dist is missing or stale.
 
-    Mirrors the staleness logic used by ``_tui_build_needed()`` for the TUI.
     The Vite build outputs to ``hermes_cli/web_dist/`` (per vite.config.ts
     outDir: "../hermes_cli/web_dist"), NOT to ``web/dist/``.  Uses the Vite
     manifest as the sentinel because it is written last and therefore has the

tests/hermes_cli/test_tui_npm_install.py

@@ -25,12 +25,6 @@ def _touch_tui_entry(root: Path) -> None:
     entry.write_text("console.log('tui')")
 
 
-def _touch_ink_bundle(root: Path) -> None:
-    bundle = root / "packages" / "hermes-ink" / "dist" / "ink-bundle.js"
-    bundle.parent.mkdir(parents=True, exist_ok=True)
-    bundle.write_text("export {}")
-
-
 def test_need_install_when_ink_missing(tmp_path: Path, main_mod) -> None:
     (tmp_path / "package-lock.json").write_text("{}")
     assert main_mod._tui_need_npm_install(tmp_path) is True
@@ -126,32 +120,3 @@ def test_no_install_prebuilt_bundle_mode(tmp_path: Path, main_mod) -> None:
     """dist/entry.js present and no package-lock.json → prebuilt bundle, skip npm install."""
     _touch_tui_entry(tmp_path)
     assert main_mod._tui_need_npm_install(tmp_path) is False
-
-
-def test_build_needed_when_source_newer_than_entry(tmp_path: Path, main_mod) -> None:
-    _touch_tui_entry(tmp_path)
-    _touch_ink(tmp_path)
-    src = tmp_path / "src" / "entry.tsx"
-    src.parent.mkdir(parents=True, exist_ok=True)
-    src.write_text("console.log('newer')")
-    os.utime(src, (200, 200))
-    os.utime(tmp_path / "dist" / "entry.js", (100, 100))
-
-    assert main_mod._tui_need_npm_install(tmp_path) is False
-    assert main_mod._tui_build_needed(tmp_path) is True
-
-
-def test_build_not_needed_when_entry_exists_and_sources_unchanged(tmp_path: Path, main_mod) -> None:
-    _touch_tui_entry(tmp_path)
-    _touch_ink(tmp_path)
-
-    assert main_mod._tui_need_npm_install(tmp_path) is False
-    assert main_mod._tui_build_needed(tmp_path) is False
-
-
-def test_build_not_needed_when_entry_and_ink_bundle_present(tmp_path: Path, main_mod) -> None:
-    _touch_tui_entry(tmp_path)
-    _touch_ink(tmp_path)
-    _touch_ink_bundle(tmp_path)
-
-    assert main_mod._tui_build_needed(tmp_path) is False