diff --git a/CODE-AUDIT.md b/CODE-AUDIT.md
index bf2c262..adf1ce9 100644
--- a/CODE-AUDIT.md
+++ b/CODE-AUDIT.md
@@ -495,7 +495,7 @@ token system + shared primitives (UI/SIMP — high value, larger effort) · i18n
   hand-synced color constants (a "keep in sync" comment guards them).
 - [x] **L60 — `'external-url'` channel name lacks the `category:` prefix** every other IPC channel uses.
 - [x] **L61 — `taskbarProgress` is the lone `ipcMain.on`** (fire-and-forget) amid all-`invoke` channels.
-- [ ] **L62 — "Best available" synthetic format hardcodes `ext:'mp4'`/`hasAudio:true`** (probe.ts) —
+- [x] **L62 — "Best available" synthetic format hardcodes `ext:'mp4'`/`hasAudio:true`** (probe.ts) —
   mislabels when the chosen container is mkv/webm.
 - [x] **L63 — `audioQuality()` unknown label → silent `'0'` (best)** — the audio analog of H5.
 - [ ] **L64 — `ARIA2C_ARGS` connection params hardcoded** (`-x16 -s16 -k1M`), no user control.
diff --git a/src/main/probe.ts b/src/main/probe.ts
index 3bef06e..266ceb3 100644
--- a/src/main/probe.ts
+++ b/src/main/probe.ts
@@ -69,7 +69,10 @@ function buildVideoFormats(raw: RawFormat[]): FormatOption[] {
   const options = [...bestByHeight.values()]
     .sort((a, b) => (b.height ?? 0) - (a.height ?? 0))
     .map(toOption)
-  options.unshift({ id: BEST_FORMAT_ID, label: 'Best available', ext: 'mp4', hasAudio: true })
+  // No `ext`: the final container for the auto-best pick depends on the user's
+  // videoContainer setting (mp4/mkv/webm), unknown here -- claiming 'mp4' would
+  // mislabel mkv/webm outputs (L62). hasAudio is always true (best merges audio).
+  options.unshift({ id: BEST_FORMAT_ID, label: 'Best available', hasAudio: true })
   return options
 }