docs(agents): fix dangling xref and sweep conventions.md Wake injection

Review fixes for #4879 (argus):
- mcp.md: the 'Waking the agent' cross-ref pointed at Core tools, which
  never mentions UpsertTodo/HIVE_AGENT_SOCKET. Point it at
  docs/tools/bash.md's 'Completion as a todo (loose-ends v2)' section,
  which documents the actual upsert/signal/clear mechanism.
- conventions.md 'Wake injection': still framed AgentRequest::Wake (a
  type that no longer exists) as the live wake surface with matrix/forge
  as callers. hive_core_agent_sock::Request::Wake has exactly one
  non-test reference on origin/main (the handler at
  socket_server/mod.rs:307) and no client; matrix/bash/forge all moved
  to the in-agent todo socket. Rewritten to match, linking mcp.md's
  'Waking the agent' section instead of duplicating it.

docs/tools/matrix.md:136-137 has the same stale AgentRequest::Wake claim
(and contradicts its own :159-165) but is out of scope (#4136) — noted
as a follow-up in the PR body instead of edited.

docs/process/conventions.md

@@ -60,15 +60,18 @@ hive-c0re owns the host admin socket.
 
 ### Wake injection
 
-`AgentRequest::Wake { from, body }` (and the manager-flavour mirror)
-is the wake-event-injection surface. Recipient is implicit — the
-agent the socket belongs to — and `from` is caller-chosen so the
-wake prompt can label the source verbatim (`"matrix: new message in
-#general"`, `"forge: PR #42 opened"`, etc.). <!-- lint:allow: example strings, not real tags -->
-Typical caller: an
-in-container background task (the matrix daemon, a scraper, the
-forge-notify webhook subscriber) that needs to signal "external work
-has arrived" without going through the broker as a peer agent.
+`hive_core_agent_sock::Request::Wake { from, body }` is the
+wake-event-injection surface on the host-served per-agent socket.
+Recipient is implicit — the agent the socket belongs to — and `from`
+is caller-chosen so the wake prompt can label the source verbatim
+(`"matrix: new message in #general"`, `"forge: PR #42 opened"`, etc.). <!-- lint:allow: example strings, not real tags -->
+`hive-c0re` still handles it, but no built-in
+in-container producer calls it today — matrix, bash and forge
+notifications all upsert a todo on the harness's in-agent socket
+(`HIVE_AGENT_SOCKET`) instead, which signals the same turn loop without
+a hive-c0re round-trip. See
+[`docs/turn-loop/mcp.md` § Waking the agent from inside the
+container](../turn-loop/mcp.md#waking-the-agent-from-inside-the-container).
 
 Identity = socket means anything that can connect to
 `/run/hive/mcp.sock` is implicitly trusted to inject wakes. That's

docs/turn-loop/mcp.md

@@ -180,11 +180,14 @@ hive_name?, swarm_name?, matrix_accounts? }`. `matrix_accounts` is a
 
 The built-in producers (matrix, bash, forge) no longer dial a direct
 wake — all three now upsert a todo on the harness's in-agent socket
-(`HIVE_AGENT_SOCKET`, `UpsertTodo`, see [Inbox](#core-tools-always-available)
-above): a new or changed summary makes the harness signal its own turn
-loop, with no hive-c0re round-trip. An external MCP server (or any
-other in-container process) can push its own todo the same way —
-`subsystem` is a plain string, not a closed set.
+(`HIVE_AGENT_SOCKET`, `UpsertTodo` — see
+[`docs/tools/bash.md` § Completion as a todo
+(loose-ends v2)](../tools/bash.md#completion-as-a-todo-loose-ends-v2)
+for the full upsert/signal/clear mechanism): a new or changed summary
+makes the harness signal its own turn loop, with no hive-c0re
+round-trip. An external MCP server (or any other in-container process)
+can push its own todo the same way — `subsystem` is a plain string,
+not a closed set.
 
 The host-served per-agent socket at `/run/hive/mcp.sock` still carries
 a lower-level `Wake` request (`hive_core_agent_sock::Request::Wake {