Gateway: show subagent requests on the parent's card, and settle threads

docs/api.md

@@ -75,10 +75,17 @@ FeedItem {
   "phase": "waiting_for_approval",
   "updatedAt": "2026-11-01T09:41:00.000Z",
   "lastMessage": "Parser and tests are written. I want to run the suite.",
-  "request": PendingRequest | null
+  "request": PendingRequest | null,
+  "via": { "hostId": "...", "threadId": "...", "title": "Check Panama PATH" } | null
 }
 ```
 
+Threads an agent started for another thread (subagents and `delegate_task` children) do not get
+their own cards. When one waits on you, its request moves onto the card of the thread that started
+it. `via` names the subagent, `request` and `phase` are the subagent's, and the answer goes to the
+subagent: `POST /v1/threads/<via.hostId>/<via.threadId>/respond`. A subagent keeps its own card
+when the gateway cannot find its parent, or the parent already shows a request.
+
 `phase` is one of `starting`, `running`, `waiting_for_approval`, `waiting_for_input`, `completed`, or
 `failed`. `lastMessage` is the agent's latest message trimmed to about 280 characters. It can be null
 for a moment after a thread changes.
@@ -133,6 +140,16 @@ POST /v1/threads/:hostId/:threadId/stop
 202
 ```
 
+```
+POST /v1/threads/:hostId/:threadId/settle
+202
+```
+
+Settles a thread, as in T3. A settled thread that finished or failed leaves the feed. To settle all
+of Recent, settle each item.
+
+Thread detail fills `request` and `via` the same way as the feed when a subagent waits on you.
+
 ## Summary
 
 The counts behind the watch face complication. It reads no thread pages, so it is cheap to call.
@@ -170,7 +187,8 @@ The new thread uses the project's default model, or the host's, and the host's d
 
 The gateway pushes when a thread starts waiting for you, finishes, or fails. Each push has an
 `aps.category` and the custom keys `hostId`, `threadId` (absent on `host` pushes), and, for
-approvals and questions, `requestId`. A `test` push carries no custom keys.
+approvals and questions, `requestId`. A `test` push carries no custom keys. A subagent's push is titled with the thread that started it,
+its body starts with "Subagent <title>:", and its `hostId` and `threadId` are the subagent's.
 
 | Category | When | Actions the watch registers |
 | --- | --- | --- |