Runtime footer: app-controlled model/context/cwd/latency/cost under replies

Hermes can append a text "runtime footer" (model, context %, workdir,
latency, cost) to final replies, but only when display.runtime_footer is
enabled in the hermes config. We want the same info but controlled by the
APP, not the gateway config. So the gateway now ALWAYS sends the data as a
structured `runtime` object on final assistant messages, and the app decides
whether/what to show.

Gateway (gateway-plugin/):
- protocol.py: new runtime_footer() helper + `runtime` field on the
  message / message.stop frames. Keys (all optional, absent when the data
  is unavailable — e.g. no cost for local models): model (vendor prefix
  dropped), context_pct (0-100), cwd (home-relative), latency (seconds),
  cost (USD).
- adapter.py: a post_api_request plugin hook captures the turn's model +
  prompt tokens + start time (platform-filtered to android so other
  platforms don't pollute the buffer). _build_runtime_footer() resolves the
  model's context window (cached, best-effort, off the event loop via
  asyncio.to_thread with a timeout) and computes context_pct. The runtime
  object is attached on every final send (streaming message.stop and
  non-streaming message, plus the fallback paths).
- outbox.py: `runtime` preserved in history reconstruction so the footer
  survives a restart / first open.

App (app/shared/):
- Protocol.kt: RuntimeMeta data class + `runtime` on MessagePayload /
  MessageStopPayload / HistoryMessage.
- ChatStore.kt: `runtime` on MessageItem, wired through live + history
  reconciliation.
- SecureStore.kt (+ Android/Desktop actuals): runtimeFooterEnabled +
  runtimeFooterFields (persisted per device).
- IrisController.kt: StateFlows + toggleRuntimeFooter() /
  toggleRuntimeField(); RUNTIME_FIELD_KEYS / default set / parser.
- SettingsScreen.kt: "Runtime footer" switch; when on, an expandable chip
  menu (Model · Context % · Workdir · Latency · Cost) to pick fields.
- ChatScreen.kt: footer rendered on the SAME line as the timestamp (footer
  left, time right, Telegram-style), only for final non-streaming assistant
  answers; Inspector pane now shows the runtime fields too.

Docs: 04-wire-protocol.md + frames.schema.json document the `runtime`
object.

Verified end-to-end on device: final replies carry
`qwen3.8-27B-exl3-4.5bpw · 53% · ~ · 38s` with the time right-aligned on
the same line; 69/69 gateway tests pass, Kotlin builds + tests pass.

docs/protocol/frames.schema.json

@@ -38,12 +38,13 @@
           "reply_to": { "type": "string" },
           "model": { "type": "string" },
           "tokens": { "type": "integer" },
+          "runtime": { "$ref": "#/definitions/runtime" },
           "ts": { "type": "integer", "description": "epoch millis" }
         }
       },
       "message.start": { "payload": { "message_id": { "type": "string" }, "role": { "type": "string" } } },
       "message.update": { "payload": { "message_id": { "type": "string" }, "text": { "type": "string", "description": "Full current text (app replaces)." } } },
-      "message.stop": { "payload": { "message_id": { "type": "string" }, "final_text": { "type": "string" }, "reasoning": { "type": "string" }, "model": { "type": "string" }, "tokens": { "type": "integer" }, "ts": { "type": "integer" } } },
+      "message.stop": { "payload": { "message_id": { "type": "string" }, "final_text": { "type": "string" }, "reasoning": { "type": "string" }, "model": { "type": "string" }, "tokens": { "type": "integer" }, "runtime": { "$ref": "#/definitions/runtime" }, "ts": { "type": "integer" } } },
       "message.deleted": { "description": "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 drop them from their cache; also outboxed so an offline device learns of the deletion on its next sync.", "payload": { "message_ids": { "type": "array", "items": { "type": "string" } } } },
       "commentary": { "description": "Intermediate assistant beat.", "payload": { "message_id": { "type": "string" }, "text": { "type": "string" } } },
       "tool.start": { "payload": { "index": { "type": "integer" }, "name": { "type": "string" }, "preview": { "type": "string" }, "args": { "type": "object" } } },
@@ -62,7 +63,7 @@
       "error": { "payload": { "code": { "type": "string", "enum": ["auth", "not_found", "rate_limited", "media_too_large", "unsupported", "internal"] }, "message": { "type": "string" } } },
       "pong": { "payload": { "ts": { "type": "integer" } } },
       "sync.done": { "payload": { "cursor": { "type": "integer" } } },
-      "history": { "description": "Paged full message history for a chat/thread (response to a history request). Reconstructed from the outbox log; used to populate the view on first open / after a process death, since sync only replays the outbox delta.", "payload": { "messages": { "type": "array", "items": { "type": "object", "properties": { "message_id": {"type":"string"}, "role": {"type":"string","enum":["user","assistant"]}, "text": {"type":"string"}, "reasoning": {"type":"string"}, "model": {"type":"string"}, "tokens": {"type":"integer"}, "ts": {"type":"integer"}, "media": {"type":"array","items":{"$ref":"#/definitions/media_ref"}} } } }, "has_more": { "type": "boolean", "description": "True when older pages exist." }, "oldest_message_id": { "type": "string", "description": "before_message_id for the next (older) page." } } },
+      "history": { "description": "Paged full message history for a chat/thread (response to a history request). Reconstructed from the outbox log; used to populate the view on first open / after a process death, since sync only replays the outbox delta.", "payload": { "messages": { "type": "array", "items": { "type": "object", "properties": { "message_id": {"type":"string"}, "role": {"type":"string","enum":["user","assistant"]}, "text": {"type":"string"}, "reasoning": {"type":"string"}, "model": {"type":"string"}, "tokens": {"type":"integer"}, "runtime": {"$ref":"#/definitions/runtime"}, "ts": {"type":"integer"}, "media": {"type":"array","items":{"$ref":"#/definitions/media_ref"}} } } }, "has_more": { "type": "boolean", "description": "True when older pages exist." }, "oldest_message_id": { "type": "string", "description": "before_message_id for the next (older) page." } } },
       "media.pull.end": { "payload": { "ok": { "type": "boolean" } } },
       "media.upload.ack": { "description": "Response to media.upload.end; ref is cached and usable in message.send media_refs.", "payload": { "ok": { "type": "boolean" }, "media_ref": { "type": "string" } } },
       "commands.catalog": { "description": "Response to a commands.catalog request: the gateway's slash-command catalog for the app's '/' drawer. Derived from hermes' COMMAND_REGISTRY (gateway-available subset) plus plugin-registered commands. The app fuzzy-matches the typed prefix client-side.", "payload": { "commands": { "type": "array", "items": { "type": "object", "properties": { "name": { "type": "string", "description": "Canonical command with leading slash, e.g. \"/new\"." }, "description": { "type": "string" }, "args_hint": { "type": "string", "description": "Argument placeholder, e.g. \"[name]\"; empty when none." }, "category": { "type": "string", "description": "Registry category (Session, Configuration, Tools & Skills, Info, Exit, Plugin)." }, "aliases": { "type": "array", "items": { "type": "string" }, "description": "Alternative names with leading slash, e.g. [\"/reset\"] for /new." } } } } } }
@@ -93,7 +94,8 @@
   "definitions": {
     "kind": { "type": "string", "enum": ["image", "audio", "video", "document", "voice"] },
     "channel": { "type": "object", "properties": { "chat_id": {"type":"string"}, "name": {"type":"string"}, "kind": {"type":"string","enum":["default","channel","thread"]}, "parent_chat_id": {"type":["string","null"]}, "is_default": {"type":"boolean"}, "archived": {"type":"boolean"}, "auto": {"type":"boolean","description":"Optional; true on channel.created for a gateway-minted auto-thread."}, "favorite": {"type":"boolean","description":"Optional; cosmetic favorite flag (sorts to the top of the list)."}, "icon": {"type":["string","null"],"description":"Optional; cosmetic icon, a base64-encoded image (PNG/JPEG). Absent/null = auto-generated letter avatar."}, "color": {"type":["string","null"],"description":"Optional; cosmetic avatar color override (#RRGGBB). Absent/null = auto-generated name-hash color."}, "automation": {"type":"boolean","description":"Optional; true when the channel is an automation channel (read-only for the user; only receives gateway-originated output such as cron jobs and webhooks). The app hides the composer and the gateway rejects message.send into it. Never set on the default channel."} } },
-    "media_ref": { "type": "object", "properties": { "media_id": {"type":"string"}, "kind": { "$ref": "#/definitions/kind" }, "mime": {"type":"string"}, "size": {"type":"integer"}, "filename": {"type":"string"}, "message_id": {"type":"string","description":"Optional; set on media.offer to associate the offer with the assistant message it belongs to."} } }
+    "media_ref": { "type": "object", "properties": { "media_id": {"type":"string"}, "kind": { "$ref": "#/definitions/kind" }, "mime": {"type":"string"}, "size": {"type":"integer"}, "filename": {"type":"string"}, "message_id": {"type":"string","description":"Optional; set on media.offer to associate the offer with the assistant message it belongs to."} } },
+    "runtime": { "type": "object", "description": "Structured runtime-metadata footer (app-controlled display). The gateway ALWAYS sends it on final assistant messages; whether/what is shown is a per-app setting (Settings -> Runtime footer), NOT a hermes config. All keys optional; absent when the data is unavailable (e.g. local models have no cost).", "properties": { "model": {"type":"string","description":"Bare model id, vendor prefix dropped (gpt-5.4)."}, "context_pct": {"type":"integer","description":"Last-call context occupancy, 0-100."}, "cwd": {"type":"string","description":"Home-relative working dir (~)."}, "latency": {"type":"number","description":"Wall-clock turn duration, seconds."}, "cost": {"type":"number","description":"Turn cost, USD."} } }
   },
   "x-planned-frames": [
     { "name": "picker.model", "direction": "server_to_app", "note": "Model/provider picker prompt. Planned, not implemented." },