Clarify 0087 directive-order harness comments

Address CoPilot review on #225 (both threads resolved there but the
edits landed after the squash-merge).

- test_observability.py: reword the 135 support-comment from "key
  order" to "document (dict insertion) order", matching the loader
  guard-comment and removing the sorted-by-key ambiguity.
- test_fixture_parsing.py: correct the 135 parse-deferral reason. It
  read "not implemented", but 0087 is implemented -- only the parse
  shape is deferred, because 135 reuses the augment/capture directive
  shapes the cross-cap parser does not model (as siblings 043-046),
  runtime-driven in test_observability.

Comment-only; no behavior change.

Author: chris-colinsky

tests/conformance/test_fixture_parsing.py

@@ -628,8 +628,13 @@ def _id(case: tuple[str, Path]) -> str:
         "Proposal 0084 nested-fan-out span lineage; not implemented"
     ),
     # Proposal 0087 (within-node directive execution order, v0.82.0).
+    # 135 reuses the augment_metadata / capture_invocation_metadata_into
+    # directive shapes (as 043-046 above) the cross-cap parser does not
+    # model; runtime-driven via test_observability, so parse stays deferred.
     "observability/135-within-node-directive-execution-order": (
-        "Proposal 0087 within-node directive execution order; not implemented"
+        "Proposal 0087 implemented; reuses the 043-046 augment/capture "
+        "directive shapes the cross-cap parser does not model, "
+        "runtime-driven in test_observability"
     ),
     # Proposal 0086 (PromptManager default cache_ttl_seconds, v0.79.0) -- the
     # manager default-cache-ttl directive shape.

tests/conformance/test_observability.py

@@ -105,8 +105,8 @@ def _reset_otel_global_tracer_provider(restore_to: object) -> None:
         # metadata_into in opposite document order across two cases; the
         # captured snapshot diverges only if a node's sibling directives
         # run in fixture order. Reuses the 043/045 metadata driver, which
-        # iterates node directives in key order -- see
-        # _apply_metadata_directives.
+        # iterates node directives in document (dict insertion) order --
+        # see _apply_metadata_directives.
         "135-within-node-directive-execution-order",
         "001-otel-basic-trace",
         "002-otel-subgraph-hierarchy",