fix(rules): the staleness signal must not wait for prior art to match (#3244)

CI caught two things, and the first is the feature not working rather than a
test being wrong.

THE SIGNAL WAS GATED ON A COINCIDENCE. build_write_path_hint returns early
when no prior art, stamp, divergence or derive matched, and that guard sat
ABOVE the new arm — so a session whose rules had changed was told only if the
file it happened to be editing also matched something else. A staleness
signal that fires on that coincidence is not a staleness signal. The arm now
runs above the guard, collecting into its own list that `lines` is seeded
from, and the guard accounts for it.

The standing-rule arm (milestone 307) is deliberately LEFT below that guard,
and this is a finding rather than a fix: it has the same gating and probably
should not, but it runs a SEMANTIC search, so lifting it would put an
embedding query on every write in every session. That is a cost decision, not
a bug fix, and not this task's to make.

THE MARKER MUST NOT BREAK THE PAYLOAD IT DECORATES. rules_etag is computed on
the SessionStart path, where `max()` raising costs the whole context payload
— every rule title, the project, all of it — to save a hint. A row with no
usable timestamp is now skipped and a set with none degrades to a count-only
marker, which still catches a rule added or deleted and only loses edits.
That is the right way round to lose information. CI found it because
build_session_context's tests pass MagicMock rules and `max()` over those
raises TypeError.

Also: list_always_on_rules on an install with no always-on rulebooks returns
`rules_etag: "empty|0"`. Its exact-dict test is updated rather than loosened
— the key being present on an empty install is the behaviour, not noise.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/scribe/mcp/tools/rulebooks.py

@@ -122,8 +122,9 @@ async def delete_rulebook(rulebook_id: int, confirmed: bool = False) -> dict:
             "confirmed_required": True,
         }
     batch = await trash_svc.delete(uid, "rulebook", rulebook_id)
-    return {"deleted": rulebook_id, "deleted_batch_id": batch,
-            "message": f"Moved to trash. Restore with restore('{batch}')."}
+    return {"deleted": rulebook_id, "title": rb.title, "deleted_batch_id": batch,
+            "message": f'Rulebook {rulebook_id} ("{rb.title}") moved to trash. '
+                       f"Restore with restore('{batch}')."}
 
 
 # ── Topic CRUD ─────────────────────────────────────────────────────────
@@ -192,8 +193,9 @@ async def delete_topic(topic_id: int, confirmed: bool = False) -> dict:
             "confirmed_required": True,
         }
     batch = await trash_svc.delete(uid, "topic", topic_id)
-    return {"deleted": topic_id, "deleted_batch_id": batch,
-            "message": f"Moved to trash. Restore with restore('{batch}')."}
+    return {"deleted": topic_id, "title": topic.title, "deleted_batch_id": batch,
+            "message": f'Topic {topic_id} ("{topic.title}") moved to trash. '
+                       f"Restore with restore('{batch}')."}
 
 
 # ── Rule CRUD ──────────────────────────────────────────────────────────
@@ -602,8 +604,10 @@ async def rule_history(rule_id: int, version_id: int = 0) -> dict:
     versions = await rulebooks_svc.list_rule_versions(rule_id, uid)
     if versions is None:
         raise ValueError(f"rule {rule_id} not found")
+    rule = await rulebooks_svc.get_rule(rule_id, uid)
     return {
         "rule_id": rule_id,
+        "title": rule.title if rule else "",
         "versions": [v.to_dict(include_text=False) for v in versions],
         "total": len(versions),
         # Said in-band because an empty list is the ordinary case and reads
@@ -632,8 +636,9 @@ async def delete_rule(rule_id: int, confirmed: bool = False) -> dict:
             "confirmed_required": True,
         }
     batch = await trash_svc.delete(uid, "rule", rule_id)
-    return {"deleted": rule_id, "deleted_batch_id": batch,
-            "message": f"Moved to trash. Restore with restore('{batch}')."}
+    return {"deleted": rule_id, "title": rule.title, "deleted_batch_id": batch,
+            "message": f'Rule {rule_id} ("{rule.title}") moved to trash. '
+                       f"Restore with restore('{batch}')."}
 
 
 # ── Subscriptions ──────────────────────────────────────────────────────