Long-press message selection + delete (message.delete frame, outbox removal, all-device sync)

docs/04-wire-protocol.md

@@ -63,7 +63,17 @@ Streaming a bubble. `update` carries the **full** current text (app replaces).
 {"type":"message.start","chat_id":"…","payload":{"message_id":"m_9002","role":"assistant"}}
 {"type":"message.update","chat_id":"…","payload":{"message_id":"m_9002","text":"partial…"}}
 {"type":"message.stop","chat_id":"…","payload":{"message_id":"m_9002","final_text":"full…",
-   "reasoning":"…","model":"…","tokens":11}}
+    "reasoning":"…","model":"…","tokens":11}}
+```
+
+### `message.deleted`
+The given message(s) were deleted from a chat/thread. Response to a
+`message.delete` request (`id` set) **and** broadcast to every device so all of
+them drop the message(s) from their cache. Also outboxed, so a device that was
+offline learns of the deletion on its next `sync`.
+```json
+{"type":"message.deleted","id":30,"chat_id":"android:default","thread_id":null,
+ "payload":{"message_ids":["m_9001","m_9002"]}}
 ```
 
 ### `commentary`
@@ -300,6 +310,16 @@ Load a page of messages for a chat/thread (initial open, scroll-up pagination).
 `before_message_id` — return messages older than this (omit for newest page).
 `limit` — max messages (default 50, max 200).
 
+### `message.delete`
+Delete the given message(s) from a chat/thread. The server removes them from the
+outbox (so `history`/`sync` no longer return them) and broadcasts
+`message.deleted` to every device. Idempotent: a message already gone (pruned by
+retention) still yields a `message.deleted` broadcast so live caches drop it.
+```json
+{"type":"message.delete","id":30,"chat_id":"android:default","thread_id":null,
+ "payload":{"message_ids":["m_9001","m_9002"]}}
+```
+
 ### `commands.catalog`
 Fetch the full slash-command catalog (for the `Menü` bottom sheet).
 ```json
@@ -346,10 +366,11 @@ Keepalive. `{"type":"ping","payload":{"ts":1724000000000}}` → `pong`.
 
 - Frames are ordered per connection (TCP/WS). Streaming `message.update` frames
   for a `message_id` are monotonic; the app may coalesce to the latest.
-- Terminal frames (`message`, `message.stop`, `tool.end`, `notification`,
-  `picker.*`, `channel.*`, `agent.busy`, `agent.idle`, `history`,
-  `commands.catalog`, `commands.complete`) are **never dropped** under
-  backpressure; only intermediate `message.update`/`tool.progress` are coalesced.
+- Terminal frames (`message`, `message.stop`, `message.deleted`, `tool.end`,
+  `notification`, `picker.*`, `channel.*`, `agent.busy`, `agent.idle`,
+  `history`, `commands.catalog`, `commands.complete`) are **never dropped**
+  under backpressure; only intermediate `message.update`/`tool.progress` are
+  coalesced.
 - Anything not delivered live goes to the **outbox** and is replayed by `sync`.
 - **Broadcast:** channel directory events (`channel.*`) and read-receipts are
   pushed to **all** connected devices for that gateway (no subscribe step).