Auto-install imageio-ffmpeg when missing (fixes existing-venv users)

v0.12.6 added imageio-ffmpeg to ML_COMPONENTS.core, but users with venvs
created before v0.12.6 won't get it until they reinstall the ML
environment. They saw the very error message my own code prints:
  "ffmpeg not found. Install ffmpeg (e.g. brew install ffmpeg ...)
   or pip install imageio-ffmpeg for a bundled fallback"

Fix: have _resolve_ffmpeg() pip-install imageio-ffmpeg on demand the
first time it's needed. ~30 MB platform-specific wheel; cached for all
future runs. Same path serves any user (mac/win/linux) on a stale venv,
not just macOS.

Also extended env:check to include imageio_ffmpeg in the import probe so
a stale venv now triggers the setup wizard on app launch.

Author: nodeeeeee

downloader.py

@@ -901,18 +901,44 @@ def _resolve_ffmpeg() -> str | None:
       1. System ffmpeg in PATH (best — usually fastest, tracks user updates)
       2. imageio-ffmpeg's bundled binary (cross-platform fallback for macOS
          and any system without ffmpeg installed; pip-installable, no admin
-         rights needed)
+         rights needed). If imageio-ffmpeg isn't present (e.g. the user has
+         a venv from an older AutoNote release that pre-dates this fallback),
+         install it on demand — it's a single platform-specific wheel under
+         30 MB and the binary is cached for future runs.
     """
     from shutil import which
     sys_ff = which("ffmpeg")
     if sys_ff:
         return sys_ff
+
+    def _try_imageio() -> str | None:
+        try:
+            import imageio_ffmpeg
+            return imageio_ffmpeg.get_ffmpeg_exe()
+        except ImportError:
+            return None
+        except Exception as e:
+            tqdm.write(f"  [warn] imageio-ffmpeg get_ffmpeg_exe failed: {e}")
+            return None
+
+    ff = _try_imageio()
+    if ff:
+        return ff
+
+    # Auto-install on first need. Quiet, fast, idempotent.
+    tqdm.write("  ffmpeg not found locally — installing imageio-ffmpeg fallback…")
     try:
-        import imageio_ffmpeg
-        return imageio_ffmpeg.get_ffmpeg_exe()
-    except Exception:
+        import subprocess as _sp
+        _sp.run(
+            [sys.executable, "-m", "pip", "install", "--quiet", "--disable-pip-version-check", "imageio-ffmpeg"],
+            check=True, timeout=180,
+        )
+    except Exception as e:
+        tqdm.write(f"  [warn] auto-install imageio-ffmpeg failed: {e}")
         return None
 
+    return _try_imageio()
+
 
 def _run_ffmpeg_hls(stream_url: str, out_path: Path, progress_cb) -> None:
     """Download an HLS master.m3u8 stream to *out_path* via ffmpeg.

electron/main.js

@@ -996,7 +996,7 @@ function registerIpc() {
     if (hasPython) {
       try {
         const r = spawnSync(VENV_PYTHON,
-          ['-c', 'import tqdm, requests, openai, canvasapi, PIL, fitz, pptx; print("ok")'],
+          ['-c', 'import tqdm, requests, openai, canvasapi, PIL, fitz, pptx, imageio_ffmpeg; print("ok")'],
           { timeout: 10000, windowsHide: true });
         coreOk = (r.status === 0 && (r.stdout || '').toString().includes('ok'));
       } catch {}

electron/package.json

@@ -1,6 +1,6 @@
 {
   "name": "auto-note",
-  "version": "0.12.6",
+  "version": "0.12.7",
   "description": "AutoNote — lecture notes generator from Canvas recordings",
   "homepage": "https://github.com/nodeeeeee/Auto-Note",
   "author": {