fix: silent pipeline log and server indexing progress

Three issues caused the Logs view to appear blank during a real pipeline run:

1. `from run import step_fetch, step_link` was outside the worker's
   try/except/finally. An import failure silently killed the thread,
   leaving _pipeline_done uncalled and the Run button stuck disabled
   forever. Now wrapped in its own try/except that posts the error to
   the log and resets the UI.

2. `build_server_index` makes N sequential HTTP requests (one per mod
   folder's meta.cpp) with no output during the scan. Added an optional
   `progress_fn(current, total, name)` callback; step_fetch wires it to
   print progress every 25 folders so the log never goes silent.

3. No immediate feedback after clicking Start — the log was blank until
   the worker thread started printing. Now posts a "Pipeline started"
   banner from the main thread before the worker launches.

CLAUDE.md

@@ -112,6 +112,10 @@ Pass 2 builds `ok_disk_names` — the set of disk names that already match the s
 
 **GUI threading model:** Every network or long-running operation runs in a `threading.Thread(daemon=True)` so the Tkinter event loop is never blocked. The only safe way to update widgets from a background thread is `self.after(0, callback)` — never touch widgets directly from a worker thread. `_poll_log` drains the entire log queue in one `after(80, ...)` tick and does a single batched `CTkTextbox.insert()` call rather than one per log entry, keeping the UI smooth even when `tqdm` emits many rapid updates during downloads. The wizard's "Test Connection" button follows the same pattern: `requests.get` runs in a daemon thread; the result is posted back via `self.after(0, ...)` with widget references captured *before* the thread starts, so stale references cannot update the wrong widgets if the user navigates away mid-request.
 
+**`run_pipeline` worker — import guard:** `from run import step_fetch, step_link` is performed inside its own `try/except` *before* stdout is redirected. If this import fails for any reason the exception is posted to the log via `self.after(0, ...)` and `_pipeline_done` is called so the UI resets cleanly. Previously an import failure would silently kill the worker thread and leave the pipeline button disabled forever.
+
+**`build_server_index` progress callback:** Accepts an optional `progress_fn(current, total, name)` callback. `step_fetch` in `run.py` uses this to print `Indexing N/M: @FolderName` every 25 folders so the log never goes silent during the server scan phase. The library itself never calls `print` — the caller owns the I/O.
+
 ### GUI localization (`gui/locales.py`)
 
 All user-facing strings are centralised in `gui/locales.py`. Two languages are supported: English (`"en"`) and Vietnamese (`"vi"`).

arma_modlist_tools/fetcher.py

@@ -81,7 +81,11 @@ def make_session(auth: tuple[str, str]) -> requests.Session:
     return s
 
 
-def build_server_index(base_url: str, auth: tuple[str, str]) -> dict:
+def build_server_index(
+    base_url: str,
+    auth: tuple[str, str],
+    progress_fn: "Callable[[int, int, str], None] | None" = None,
+) -> dict:
     """
     Scan the root of the file server and build mod lookup maps.
 
@@ -90,6 +94,9 @@ def build_server_index(base_url: str, auth: tuple[str, str]) -> dict:
 
     :param base_url: Root URL of the Caddy file server (trailing slash optional).
     :param auth: ``(username, password)`` tuple for HTTP Basic Auth.
+    :param progress_fn: Optional callback called as ``progress_fn(current, total, name)``
+                        after each folder is processed.  Use it to report progress without
+                        coupling the library to ``print`` or any specific I/O sink.
     :returns: Dict with keys:
 
               - ``by_steam_id`` — ``{steam_id: folder_url}``
@@ -100,11 +107,12 @@ def build_server_index(base_url: str, auth: tuple[str, str]) -> dict:
     root = base_url.rstrip("/") + "/"
     items = _list_dir(root, session)
     folders = [it for it in items if it.get("is_dir")]
+    total = len(folders)
 
     by_steam_id: dict[str, str] = {}
     by_name: dict[str, str] = {}
 
-    for folder in folders:
+    for i, folder in enumerate(folders, 1):
         name = folder["name"].strip("/")
         url = _folder_url(root, name)
         by_name[_normalize_name(name)] = url
@@ -118,6 +126,9 @@ def build_server_index(base_url: str, auth: tuple[str, str]) -> dict:
         except requests.RequestException:
             pass  # meta.cpp missing or unreachable — name-based fallback still works
 
+        if progress_fn is not None:
+            progress_fn(i, total, name)
+
     return {"by_steam_id": by_steam_id, "by_name": by_name, "folders": folders}
 
 

gui/app.py

@@ -143,11 +143,22 @@ class ArmaModManagerApp(ctk.CTk):
         self._pipeline_running = True
         self._get_dashboard().set_pipeline_ui(running=True)
         self.navigate_to("Logs")
+        # Post an immediate banner so the log is never blank after clicking Start.
+        _sep = "=" * 50
+        self.post_log(f"\n{_sep}\n  {t('pipeline.starting')}\n{_sep}\n\n")
 
         def worker() -> None:
             # run.py calls fix_console_encoding() at import time, which needs
             # the real sys.stdout.buffer. Import it before we redirect stdout.
-            from run import step_fetch, step_link
+            try:
+                from run import step_fetch, step_link
+            except Exception as _import_err:
+                self.after(0, lambda: self.post_log(
+                    f"\n✗  Failed to load pipeline: {_import_err}\n"
+                ))
+                self.after(0, self._pipeline_done)
+                return
+
             self._redirect_output()
             try:
                 from arma_modlist_tools.parser  import parse_modlist_html

gui/locales.py

@@ -26,6 +26,7 @@ _EN: dict[str, str] = {
     "nav.settings":                  "Settings",
 
     # ── Pipeline step headers (printed to log) ───────────────────────────────
+    "pipeline.starting":             "Pipeline started",
     "pipeline.step1_name":           "Parse presets",
     "pipeline.step2_name":           "Compare presets",
     "pipeline.step3_name":           "Download mods",
@@ -266,6 +267,7 @@ _VI: dict[str, str] = {
     "nav.settings":                  "Cài đặt",
 
     # ── Pipeline step headers ────────────────────────────────────────────────
+    "pipeline.starting":             "Pipeline đã bắt đầu",
     "pipeline.step1_name":           "Phân tích preset",
     "pipeline.step2_name":           "So sánh preset",
     "pipeline.step3_name":           "Tải mod",

run.py

@@ -91,9 +91,14 @@ def step_fetch(cfg) -> None:
         for mod in data["mods"]:
             queue.append((mod, preset_name))
 
+    def _index_progress(current: int, total: int, name: str) -> None:
+        if current == 1 or current % 25 == 0 or current == total:
+            print(f"  Indexing {current}/{total}: {name}")
+
     print(f"  Building server index...")
-    index = build_server_index(cfg.server_url, cfg.server_auth)
-    print(f"  Indexed {len(index['by_steam_id'])} mods\n")
+    index = build_server_index(cfg.server_url, cfg.server_auth, progress_fn=_index_progress)
+    print(f"  Indexed {len(index['by_steam_id'])} mods by steam_id, "
+          f"{len(index['by_name'])} by name\n")
 
     session  = make_session(cfg.server_auth)
     resolved = []