feat(adapters): conformance suite — profiles verified not asserted (WP-0007 T4)

run_conformance/assert_conformant verify declared profile == observed behaviour
(profile validates, READ round-trips to the right shard, unclaimed verbs raise
NotSupported); ConformanceReport gives a precise capability diff. FolderAdapter
passes; lying-read and dishonest-write stubs fail. 3 tests green. (TSD §A.2)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_conformance.py

@@ -0,0 +1,67 @@
+"""Tests for the adapter conformance suite (SHARD-WP-0007 T4)."""
+
+from collections.abc import Iterable
+
+import pytest
+
+from shard_wiki.adapters import (
+    ConformanceError,
+    FolderAdapter,
+    ShardAdapter,
+    assert_conformant,
+    run_conformance,
+)
+from shard_wiki.model import CapabilityProfile, Identity, Page
+from shard_wiki.provenance import ProvenanceEnvelope
+
+
+def test_folder_adapter_is_conformant(tmp_path):
+    (tmp_path / "Home.md").write_text("# Home", encoding="utf-8")
+    report = assert_conformant(FolderAdapter("shardA", tmp_path))
+    assert report.ok
+    assert report.diff() == "conformant"
+
+
+class _LyingReadAdapter(ShardAdapter):
+    """Claims READ but read() is broken — must fail conformance."""
+
+    def __init__(self, profile: CapabilityProfile) -> None:
+        self._profile = profile
+
+    @property
+    def shard_id(self) -> str:
+        return "liar"
+
+    def profile(self) -> CapabilityProfile:
+        return self._profile
+
+    def keys(self) -> Iterable[str]:
+        return ["Home"]
+
+    def read(self, key: str) -> Page:
+        # Returns a page attributed to the WRONG shard — a lie about its own content.
+        return Page(Identity("someone-else", key), "x", ProvenanceEnvelope(source_shard="x"))
+
+
+def test_lying_read_adapter_fails_with_precise_diff(tmp_path):
+    good = FolderAdapter("shardA", tmp_path).profile()  # a valid read-only profile
+    liar = _LyingReadAdapter(good)
+    report = run_conformance(liar)
+    assert not report.ok
+    assert "read-round-trips" in report.diff()
+    with pytest.raises(ConformanceError, match="read-round-trips"):
+        assert_conformant(liar)
+
+
+class _DishonestWriteAdapter(FolderAdapter):
+    """Declares no WRITE (inherits read-only folder profile) but write() silently succeeds."""
+
+    def write(self, key: str, body: str) -> Page:  # noqa: ARG002
+        return self.read(next(iter(self.keys())))
+
+
+def test_dishonest_absence_fails(tmp_path):
+    (tmp_path / "Home.md").write_text("x", encoding="utf-8")
+    report = run_conformance(_DishonestWriteAdapter("shardA", tmp_path))
+    assert not report.ok
+    assert "honest-absence:write" in report.diff()