M3: channels/threads + cron delivery + search + outbox sync

Gateway plugin:
- ChannelDirectory (SQLite): channels + threads, friendly-name resolution
- FTS5 search bridge over state.db (scope all/chat, LIKE fallback)
- Outbox (monotonic cursor, 72h retention) for reconnect catch-up
- adapter: channel.* handlers, search, sync, cron target parsing
- ws_server: M3 frame routing + hello.ack sync cursor

App (KMP):
- ChannelStore (directory cache) + lane-aware ChatStore (per chat/thread)
- GatewayClient.sendFrame; IrisController channel/search/nav actions
- ChatScreen: channel drawer, thread toggle, topic switcher, search overlay

gateway-plugin/protocol.py

@@ -17,7 +17,7 @@ Milestone M5: notification, fcm.register, read.receipt.
 
 import json
 from dataclasses import dataclass, field
-from typing import Any, Dict, Optional
+from typing import Any, Dict, List, Optional
 
 PROTOCOL_VERSION = 1
 
@@ -50,6 +50,24 @@ TYPE_TOOL_END = "tool.end"
 # Intermediate assistant beat (M2)
 TYPE_COMMENTARY = "commentary"
 
+# Channels / threads (M3)
+TYPE_CHANNEL_CREATE = "channel.create"
+TYPE_CHANNEL_RENAME = "channel.rename"
+TYPE_CHANNEL_SET_DEFAULT = "channel.set_default"
+TYPE_CHANNEL_DELETE = "channel.delete"
+TYPE_CHANNEL_CREATED = "channel.created"
+TYPE_CHANNEL_RENAMED = "channel.renamed"
+TYPE_CHANNEL_DELETED = "channel.deleted"
+TYPE_CHANNEL_LIST = "channel.list"
+
+# Search (M3)
+TYPE_SEARCH = "search"
+TYPE_SEARCH_RESULTS = "search.results"
+
+# Reconnect catch-up (M3 outbox; extended by M5 push)
+TYPE_SYNC = "sync"
+TYPE_SYNC_DONE = "sync.done"
+
 # ---------------------------------------------------------------------------
 # Error codes (``error`` frame payload.code)
 # ---------------------------------------------------------------------------
@@ -352,6 +370,80 @@ def commentary(
     )
 
 
+# ---------------------------------------------------------------------------
+# Channel directory frames (M3)
+# ---------------------------------------------------------------------------
+
+def _channel_payload(entry: Dict[str, Any]) -> Dict[str, Any]:
+    """Project a directory entry onto the wire shape."""
+    payload: Dict[str, Any] = {
+        "chat_id": entry.get("chat_id"),
+        "name": entry.get("name"),
+        "kind": entry.get("kind", "channel"),
+    }
+    if entry.get("parent_chat_id") is not None:
+        payload["parent_chat_id"] = entry["parent_chat_id"]
+    if entry.get("is_default"):
+        payload["is_default"] = True
+    if entry.get("archived"):
+        payload["archived"] = True
+    return payload
+
+
+def channel_created(entry: Dict[str, Any]) -> Frame:
+    """Broadcast: a channel/thread was created."""
+    return Frame(type=TYPE_CHANNEL_CREATED, payload=_channel_payload(entry))
+
+
+def channel_renamed(entry: Dict[str, Any]) -> Frame:
+    """Broadcast: a channel/thread was renamed."""
+    return Frame(type=TYPE_CHANNEL_RENAMED, payload=_channel_payload(entry))
+
+
+def channel_deleted(chat_id: str) -> Frame:
+    """Broadcast: a channel was archived (soft-deleted)."""
+    return Frame(type=TYPE_CHANNEL_DELETED, payload={"chat_id": chat_id})
+
+
+def channel_list(channels: List[Dict[str, Any]]) -> Frame:
+    """Full directory (response to a ``channel.list`` request)."""
+    return Frame(
+        type=TYPE_CHANNEL_LIST,
+        payload={"channels": [_channel_payload(c) for c in channels]},
+    )
+
+
+# ---------------------------------------------------------------------------
+# Search frames (M3)
+# ---------------------------------------------------------------------------
+
+def search_results(
+    query: str,
+    scope: str,
+    hits: List[Dict[str, Any]],
+    *,
+    id: Optional[int] = None,
+) -> Frame:
+    """Response to a ``search`` request.
+
+    Each hit: ``{message_id, chat_id, thread_id, role, snippet, ts}``.
+    """
+    return Frame(
+        type=TYPE_SEARCH_RESULTS,
+        id=id,
+        payload={"query": query, "scope": scope, "hits": hits},
+    )
+
+
+# ---------------------------------------------------------------------------
+# Sync frames (M3 outbox)
+# ---------------------------------------------------------------------------
+
+def sync_done(cursor: int, *, id: Optional[int] = None) -> Frame:
+    """Terminal frame of a ``sync`` replay: the new cursor to persist."""
+    return Frame(type=TYPE_SYNC_DONE, id=id, payload={"cursor": cursor})
+
+
 def error(code: str, message: str, *, id: Optional[int] = None) -> Frame:
     return Frame(type=TYPE_ERROR, id=id, payload={"code": code, "message": message})