docs: file #358 — Ctrl+M mute chord never fires from the dispatcher

Deferred by user direction. The mute mechanism (2cf94dbc) is fine; the
chord never fires: 101 [input] actions logged in the session, zero for
AcdreamToggleAudioMute. Hypotheses ranked in the issue — merged-binding
absence (the suspicious stable '152 bindings' count), dispatcher modifier
matching, retained-UI Ctrl-chord consumption.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -37,6 +37,44 @@ null-guard with `CanExecuteLiveMovement` (the exact lifecycle set the throw
 helper accepts); cursor restore still runs unconditionally, and
 published-controller behaviour is unchanged.
 
+## #358 — Ctrl+M mute keybind never fires from the dispatcher
+
+**Status:** OPEN — filed 2026-08-08, deferred by user direction ("we can carry
+that on for later"). The mute mechanism itself is implemented and untested
+only for want of a working trigger.
+
+**Symptom:** pressing Ctrl+M in a live session does nothing. The downstream
+chain is NOT the problem — evidence from the session log:
+
+- `[input]` action logging was live (101 fired actions: movement, selection,
+  UseSelected) and recorded **zero** events for `AcdreamToggleAudioMute` —
+  the chord never fired from `InputDispatcher`, so the
+  `GameplayInputCommandController` switch case and the engine's `Muted`
+  property (verified paths, commit `2cf94dbc`) were never reached.
+- `KeyBindings.LoadOrDefault`'s merge-over-defaults was read and looks
+  correct (an action with defaults but absent from the saved file picks up
+  the default binding), so a stale `keybinds.json` SHOULD have gained the
+  new binding. Unverified whether it actually did: the client logged
+  "loaded 152 bindings" both before AND after the binding was added, which
+  is suspicious — either the pre-change default count was 151 (then 152 is
+  right) or the merge did not add it (then the count should have grown).
+  Nobody has printed the default count or dumped the merged set yet.
+
+**Hypotheses, in order:** (1) the merged set genuinely lacks the binding
+(count question above — cheapest to check first: log `RetailDefaults().Count`
+or grep the saved json after a save); (2) the dispatcher's modifier matching
+does not fire a Ctrl+M chord — e.g. exact-vs-subset modifier semantics, or
+the bare `M` binding (`SelectionNextFellow`, no modifiers) shadowing it; note
+the log shows no `SelectionNextFellow` firing on the press either, which
+leans against simple shadowing and toward the chord matching nothing at all;
+(3) the retained UI consuming Ctrl-chords before the dispatcher.
+
+**The mechanism behind the key** (already landed, `2cf94dbc`): engine
+`Muted` sets the AL listener gain 0/1 — unused since A2 moved mixing to the
+CPU, so it silences already-playing voices instantly without touching the
+retail mixing math or persisted volumes. Once the trigger works, no further
+audio-side work is needed.
+
 ## #357 — Login stalls: reveal reaches ready=True but the player is never placed; UI + sky render, world never opens
 
 **Status:** CLOSED 2026-08-08 — root-caused and fixed same session (see the