Align conformance.toml note + visible 028 skip

From PR #95 review:

- Rewrite the conformance.toml convention block to acknowledge that
  feature PRs which bump the spec submodule pin update this file
  too, setting `since` to the upcoming release version (matches the
  v0.10.0 cycle's pattern in PR #85 / #88, and how this PR works).
- Emit warnings.warn for 028's deferred augment_metadata case so
  pytest's end-of-run summary surfaces the deferred coverage by
  name rather than silently passing.

Author: chris-colinsky

conformance.toml

@@ -22,10 +22,13 @@
 # between pinned-spec and spec-head is the consumer's job (e.g., the
 # spec docs site computes the difference and renders accordingly).
 #
-# Convention: this file is only updated as part of release PRs. Between
-# releases, the manifest reflects the most-recently-published version
-# so external readers never see a `since` referring to an unreleased
-# pre-tag commit.
+# Convention: this file is updated as part of release PRs AND as part
+# of feature PRs that bump the spec submodule pin (the manifest guard
+# requires entries for every Accepted proposal in the pinned spec, so
+# a submodule bump forces this file to update too). Such bump PRs set
+# `since` to the upcoming release version; between the bump PR and the
+# matching tag, external readers will see a `since` referring to the
+# upcoming, unreleased version.
 
 [manifest]
 implementation = "openarmature-python"

tests/conformance/test_observability.py

@@ -887,12 +887,21 @@ async def _run_fixture_028(spec: Mapping[str, Any]) -> None:
         # Cases using the `augment_metadata` directive exercise §3.4
         # mid-invocation rejection at set_invocation_metadata. The
         # augment_metadata harness primitive (per fixture 034) lands
-        # with proposal 0040 / task #22; skip until then.
+        # with proposal 0040 / task #22; surface the deferral via
+        # warnings.warn so pytest's end-of-run summary lists it (rather
+        # than silently passing) and continue to the other cases.
         nodes_check = cast("dict[str, Any]", case.get("nodes", {}))
         if any(
             isinstance(n, dict) and "augment_metadata" in cast("dict[str, Any]", n)
             for n in nodes_check.values()
         ):
+            import warnings  # noqa: PLC0415
+
+            warnings.warn(
+                f"028 case {case_name!r} deferred: augment_metadata harness primitive "
+                f"lands with proposal 0040 / #22",
+                stacklevel=2,
+            )
             continue
         try:
             # Build a minimal graph from the case's nodes/edges. The