fix(6477): a body uses a canon by name only when the name can resolve to it

The proposer's reference basis, and every uses edge it writes, counted any
word-bounded mention of a canon's symbol. Three holes made that wrong at
scale (snippet #5448, symbol `file`, held 2,161 uses edges):

- Go, Rust, Kotlin, Swift, Dart, C, C#, Ruby and PHP were outside the
  language-family maps, so their canons read as "unknown, no gate" and were
  matched in every Python, TS and CSS body.
- Canons in other projects were matched by name, though one repo never
  calls a function defined in another's.
- A plain word (`file`, `seen`) or a module's own helper (`_run`) matched
  wherever it appeared.

names_canon is now the one by-name test, used by match_canon,
reference_canons and the write-path hint: same project, not a name the file
defines itself (unless the canon is recorded there), no generic verb with or
without a leading underscore, and a bare lowercase word only where it is
called. The write path keeps the payload's own names in play, since a
redefinition of a pulled canon is the copy it exists to flag.

Repair: record_uses only adds, so replace_reference_uses now makes a row's
machine-written reference edges exactly what the current rule finds,
leaving judged and hook edges alone. _PROPOSER_VERSION 7 re-reads every row
on its project's next refresh. Migration 0125 deletes the cross-project
reference edges already stored.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_integration_shape_classify.py

@@ -294,6 +294,43 @@ async def test_get_snippet_carries_the_structured_consumer_map(seeded):
     assert consumers == {"instances": [], "variants": [], "uses": []}
 
 
+@pytest.mark.integration
+async def test_a_reread_takes_back_the_reference_edges_a_looser_rule_wrote(seeded):
+    """record_uses only adds; a tightened by-name rule must also remove what
+    the old rule wrote. A judged edge on the same row survives."""
+    from grimoire.services import snippets as snippets_svc
+    from grimoire.services.shape_ledger import record_uses, replace_reference_uses
+
+    owner, pid, sid = seeded["owner"], seeded["pid"], seeded["snippet"]
+    helper = await snippets_svc.create_snippet(
+        owner, name="cls_reread_helper", code="def hash_token(raw):\n    return raw\n",
+        language="python", repo="Widget", path="src/hash.py", symbol="hash_token",
+        project_id=pid,
+    )
+    hid = int(helper.id)
+
+    async def make_app_row(s):
+        return (await s.execute(select(CodeShape).where(
+            CodeShape.project_id == pid, CodeShape.symbol == "make_app",
+        ))).scalar_one()
+
+    async with async_session() as s:
+        await record_uses(s, await make_app_row(s), [sid, hid], basis="reference")
+        await s.commit()
+    await classify_shapes(owner, pid, [
+        {"path": "src/app.py", "symbol": "make_app", "status": "exempt",
+         "reason": "its own thing", "uses": [hid]},
+    ], via="audit")
+
+    async with async_session() as s:
+        await replace_reference_uses(s, await make_app_row(s), [])
+        await s.commit()
+    _, n_sid = await list_project_shapes(owner, pid, uses=sid)
+    rows_hid, n_hid = await list_project_shapes(owner, pid, uses=hid)
+    assert n_sid == 0
+    assert n_hid == 1 and rows_hid[0].symbol == "make_app"
+
+
 @pytest.mark.integration
 async def test_sync_refiles_rows_whose_snippet_was_purged(seeded):
     """The SET NULL companion: a judgment whose target is hard-deleted