Address PR 143 review

Tighten three stale comments that still referred to a sentinel
"pair" on the failure path. The provider now emits only a single
sentinel completed event on failure (no started counterpart);
the comments in langfuse/observer.py (dispatch site + handler
docstring) and openai.py (failure-emission site) didn't catch up
with the v0.13.0 emission change in the same PR.

Author: chris-colinsky

src/openarmature/llm/providers/openai.py

@@ -461,12 +461,12 @@ async def complete(
                 # Failure path: the sentinel NodeEvent carries the
                 # error fields per llm-provider §7. LlmCompletionEvent
                 # is success-only per proposal 0049 §3 alternative 3,
-                # so failures continue to surface through the sentinel
-                # pair until the spec extends the typed event with
-                # error semantics. Only ``completed`` is emitted on
-                # failure — no started counterpart, since both bundled
-                # observers' handlers ignore sentinel-started after the
-                # v0.13.0 migration.
+                # so failures continue to surface through a sentinel
+                # ``completed`` event until the spec extends the typed
+                # event with error semantics. Only ``completed`` fires
+                # — no started counterpart, since both bundled
+                # observers' handlers ignore sentinel-started after
+                # the v0.13.0 migration.
                 dispatch(
                     _make_llm_event(
                         "completed",

src/openarmature/observability/langfuse/observer.py

@@ -369,7 +369,8 @@ async def __call__(
         # Proposal 0049 typed LlmCompletionEvent (success path). Drives
         # the §5.5 Generation observation lifecycle for successful
         # provider calls. Failures don't emit this variant; they flow
-        # through the sentinel-pair error path below.
+        # through the sentinel error path below (a single sentinel
+        # ``completed`` event — no started counterpart in v0.13.0+).
         if isinstance(event, LlmCompletionEvent):
             if not self.disable_llm_spans:
                 self._handle_typed_llm_completion(event)
@@ -1325,11 +1326,13 @@ def _observation_metadata(self, event: NodeEvent, correlation_id: str | None) ->
     # one shot at typed-event arrival, with start_time back-dated by
     # latency_ms so the observation's duration reflects the adapter-
     # boundary measurement rather than dispatcher queue delay. Failure
-    # path keeps the sentinel NodeEvent pair (LlmCompletionEvent is
-    # success-only per proposal 0049 §3 alternative 3). The provider
-    # also dropped sentinel-pair emission on the success path in this
-    # release, so on success the typed event is the only signal the
-    # Generation observation has to fire from.
+    # path keeps a single sentinel NodeEvent (``completed`` phase
+    # carrying error fields on its LlmEventPayload — LlmCompletionEvent
+    # is success-only per proposal 0049 §3 alternative 3). The provider
+    # dropped success-path sentinel emission entirely in this release,
+    # so on success the typed event is the only signal the Generation
+    # observation has to fire from; the failure path's sentinel
+    # ``started`` was also dropped, leaving only ``completed``.
     def _handle_typed_llm_completion(self, event: LlmCompletionEvent) -> None:
         """Open + close the Generation observation from the typed
         LlmCompletionEvent (success path)."""