Add interactive choice-picker menus for finite-choice slash commands

Slash commands with a finite set of options (/reasoning, /fast, ...) now
render a tappable card with buttons (2 per row, ✓ on the current value)
instead of a plain text status card. The mechanism is generic: any command
that calls the adapter's send_choice_picker() gets a picker automatically.

Wire protocol (docs/04, frames.schema.json):
- picker.choice (server→app): {picker_id, title, choices[]}
- picker.select (app→server): {picker_id, value}
- pickers capability flag now True in server_caps

gateway-plugin:
- protocol.py: picker.choice/picker.select frame types + picker_choice()
- dispatch.py: route picker.select → adapter.on_picker_select
- adapter.py: send_choice_picker() (fails cleanly with no live device so
  hermes falls back to text), on_picker_select(), in-memory pending pickers
  (gateway restart expires them; stale select is a no-op), pickers=True

app (KMP):
- Protocol.kt: PickerChoice/PickerChoicePayload + pickerSelectFrame()
- ChatStore.kt: PickerItem + onPickerChoice (idempotent) + resolvePicker
  (optimistic, one-shot)
- ChatDb.kt: persist PickerItem in the messages table (polymorphic decode)
- IrisController.kt: picker.choice routing + selectPicker() action
- ChatScreen.kt: PickerCard composable (locks after selection)

Tests:
- python: 3 picker tests (roundtrip, no-device fallback, stale-select noop)
- kotlin: ChatStorePickerTest (add/idempotent/resolve/one-shot/noop/serialize)
- fixture fix: clear leaked IRIS_HTTP_PORT/IRIS_WS_HOST env so the adapter
  binds the ephemeral port (a prior test's interactive_setup() polluted the
  process env, colliding with a live gateway on 8791)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gateway-plugin/tests/test_android.py

@@ -97,6 +97,13 @@ def plugin():
 def adapter(plugin, monkeypatch):
     """A live IrisAdapter with an isolated HERMES_HOME (conftest)."""
     monkeypatch.setenv("IRIS_TOKEN", TOKEN)
+    # Clear any IRIS transport overrides leaked into the process env by earlier
+    # tests (e.g. test_interactive_setup_prints_qr runs the real
+    # interactive_setup(), which save_env_value()s IRIS_HTTP_PORT/IRIS_WS_HOST).
+    # Without this, a later adapter would bind the leaked port (8791) instead of
+    # the ephemeral 0 below, colliding with a live gateway on that port.
+    monkeypatch.delenv("IRIS_HTTP_PORT", raising=False)
+    monkeypatch.delenv("IRIS_WS_HOST", raising=False)
     from gateway.platform_registry import PlatformEntry, platform_registry
 
     # Platform("iris") resolves only once the platform is registered
@@ -2397,4 +2404,88 @@ async def test_commands_catalog_frame_roundtrip(plugin, adapter, ws_client):
     for c in commands:
         assert c["name"].startswith("/")
         assert "description" in c and "args_hint" in c and "category" in c
-        assert isinstance(c["aliases"], list)
+        assert isinstance(c["aliases"], list)
+
+# ── Interactive pickers (picker.choice / picker.select) ───────────────────
+
+
+@pytest.mark.asyncio
+async def test_choice_picker_roundtrip(plugin, adapter, ws_client):
+    """send_choice_picker emits a picker.choice frame; a picker.select from
+    the app runs the selection callback and delivers its reply as a normal
+    final message. The picker is consumed (a second select is a no-op)."""
+    ws, _ = ws_client
+    picked: list = []
+
+    async def on_choice(chat_id, value):
+        picked.append((chat_id, value))
+        return f"picked {value}"
+
+    res = await adapter.send_choice_picker(
+        "default",
+        "Pick one",
+        [
+            {"value": "a", "label": "A", "is_current": False},
+            {"value": "b", "label": "B", "is_current": True},
+        ],
+        "sess",
+        on_choice,
+    )
+    assert res.success
+    frames = await recv_until(ws, lambda f: f.get("type") == "picker.choice")
+    pc = frames[-1]
+    assert pc["chat_id"] == "default"
+    pid = pc["payload"]["picker_id"]
+    assert pid == res.message_id
+    assert pc["payload"]["title"] == "Pick one"
+    assert pc["payload"]["choices"][1]["is_current"] is True
+
+    # The app taps a button -> picker.select.
+    await ws.send(
+        json.dumps(
+            {"type": "picker.select", "id": 1, "payload": {"picker_id": pid, "value": "b"}}
+        )
+    )
+    assert picked == [("default", "b")]
+    # The callback's reply arrives as a normal final assistant message.
+    frames2 = await recv_until(
+        ws, lambda f: f.get("type") == "message" and f["payload"].get("text") == "picked b"
+    )
+    assert frames2[-1]["payload"]["role"] == "assistant"
+    # The picker is consumed: a second select for the same id is a no-op.
+    await ws.send(
+        json.dumps(
+            {"type": "picker.select", "id": 2, "payload": {"picker_id": pid, "value": "a"}}
+        )
+    )
+    await asyncio.sleep(0.2)
+    assert picked == [("default", "b")]
+
+
+@pytest.mark.asyncio
+async def test_choice_picker_requires_live_device(adapter):
+    """With no live device the picker could never be answered, so the adapter
+    reports failure and hermes falls back to the text status card."""
+    res = await adapter.send_choice_picker(
+        "default",
+        "t",
+        [{"value": "a", "label": "A"}],
+        "s",
+        lambda c, v: "x",
+    )
+    assert not res.success
+    assert not adapter._pending_pickers
+
+
+@pytest.mark.asyncio
+async def test_picker_select_unknown_id_is_noop(plugin, adapter, ws_client):
+    """A stale picker.select (gateway restart expired the pending state) is
+    ignored without error."""
+    ws, _ = ws_client
+    await ws.send(
+        json.dumps(
+            {"type": "picker.select", "id": 1, "payload": {"picker_id": "pc_nope", "value": "a"}}
+        )
+    )
+    await asyncio.sleep(0.2)
+    assert not adapter._pending_pickers