feat(sse,tui): bump spec pin to v0.29.0 + AwaitingLlmFirstToken (v0.14.0)

Spec pin moved da93ca7 (v0.28.0) → 562001a (v0.29.0); vendored
conversation-api-spec.md + conversation_api.contract.md re-snapshotted.
The only material delta is Worldtree #201's awaiting_llm_first_token
SSE heartbeat — a top-level event (NOT a worker_phase extension, per
INV-053's three-field stability) that fires at a configurable interval
(default 5s) during the BuildingPrompt → CallingLLM gap.

Wire layer (sse_client.py):
- New `AwaitingLlmFirstToken` dataclass: sse_id / turn_id /
  elapsed_ms_since_building_prompt (server-authoritative monotonic)
- Added to Event union + _envelope_for_type dispatch branch
- Without this, ratatoskr would crash on any slow-first-token turn
  from a v0.29.0 server (unknown SSE event type → ValueError)

TUI layer (tui.py):
- Audit pipeline: per-event debug-pane line with elapsed in seconds
- Live transcript indicator: first heartbeat mounts a Static
  ("awaiting first token · 5.0s"); subsequent heartbeats update it
  in place; any non-heartbeat event removes it (the gap closed)
- Turn-summary line now carries heartbeat count
- Indicator demoted via .awaiting-label CSS so it reads as ambient
  progress, not content

Tests: 2 wire-layer (single + monotonic sequence) + 3 presenter
(audit line shape, single-mount semantic, indicator removal on gap
close). Suite: 318 passing.

tests/test_sse_client.py

@@ -6,6 +6,7 @@ import respx
 
 from ratatoskr.sse_client import (
     AffectUpdate,
+    AwaitingLlmFirstToken,
     CancelAlreadyCompleted,
     Cancelled,
     CancelResult,
@@ -955,3 +956,87 @@ class TestAffectUpdate:
         assert affect.turn_id == 42
         assert affect.snapshot is None
         assert affect.sse_id == SseId(42, 2)
+
+
+class TestAwaitingLlmFirstToken:
+    """Worldtree #201 / v0.29.0 — `awaiting_llm_first_token` SSE heartbeat.
+
+    Top-level event (not a worker_phase extension) fired during the
+    BuildingPrompt → CallingLLM gap at the configured interval (default
+    5s). Server-authoritative elapsed_ms is time.monotonic()-based and
+    monotonically increasing across the heartbeat sequence.
+
+    See docs/conversation-api-spec.md § awaiting_llm_first_token.
+    """
+
+    @respx.mock
+    async def test_single_heartbeat_parsed(self) -> None:
+        """single_heartbeat_parsed [tracer]: type=awaiting_llm_first_token →
+        AwaitingLlmFirstToken(turn_id, elapsed_ms_since_building_prompt).
+        """
+        stream = _sse_chunk(
+            "42:1",
+            {
+                "type": "awaiting_llm_first_token",
+                "turn_id": 42,
+                "elapsed_ms_since_building_prompt": 5012.3,
+            },
+        ) + _sse_chunk("42:2", _DONE_42_6)
+        respx.post("https://w.example/sessions/s1/messages").mock(
+            return_value=httpx.Response(
+                200, headers={"content-type": "text/event-stream"}, content=stream
+            )
+        )
+        async with httpx.AsyncClient(base_url="https://w.example") as client:
+            events = [e async for e in stream_turn(client, "s1", "hi")]
+        beat = events[0]
+        assert isinstance(beat, AwaitingLlmFirstToken)
+        assert beat.turn_id == 42
+        assert beat.elapsed_ms_since_building_prompt == 5012.3
+        assert beat.sse_id == SseId(42, 1)
+
+    @respx.mock
+    async def test_heartbeat_sequence_monotonic(self) -> None:
+        """heartbeat_sequence_monotonic [scenario]: three consecutive heartbeats
+        in one turn — elapsed_ms_since_building_prompt monotonically increases,
+        all carry the same turn_id.
+        """
+        stream = (
+            _sse_chunk(
+                "42:1",
+                {
+                    "type": "awaiting_llm_first_token",
+                    "turn_id": 42,
+                    "elapsed_ms_since_building_prompt": 5000.0,
+                },
+            )
+            + _sse_chunk(
+                "42:2",
+                {
+                    "type": "awaiting_llm_first_token",
+                    "turn_id": 42,
+                    "elapsed_ms_since_building_prompt": 10005.4,
+                },
+            )
+            + _sse_chunk(
+                "42:3",
+                {
+                    "type": "awaiting_llm_first_token",
+                    "turn_id": 42,
+                    "elapsed_ms_since_building_prompt": 15011.8,
+                },
+            )
+            + _sse_chunk("42:4", _DONE_42_6)
+        )
+        respx.post("https://w.example/sessions/s1/messages").mock(
+            return_value=httpx.Response(
+                200, headers={"content-type": "text/event-stream"}, content=stream
+            )
+        )
+        async with httpx.AsyncClient(base_url="https://w.example") as client:
+            events = [e async for e in stream_turn(client, "s1", "hi")]
+        beats = [e for e in events if isinstance(e, AwaitingLlmFirstToken)]
+        assert len(beats) == 3
+        elapsed = [b.elapsed_ms_since_building_prompt for b in beats]
+        assert elapsed == sorted(elapsed)  # monotonically increasing
+        assert all(b.turn_id == 42 for b in beats)