align(4909d): every rule arm that annotates reads one bar, kb_rule_threshold at 0.70

prompt_rule, pre_tool_rule and write_path_rule now share one settings key,
RULE_FLOOR_KEY = "kb_rule_threshold", default 0.70. The reply backstop keeps
its own 0.80, because there the floor is a stop bar. Moving the shared floor
through tune_retrieval or the Settings form records a tuning event on every
surface that reads it (set_dial, via retrieval_surfaces.sharing_floor), and
the result names the surfaces it carried as `moved_with`. Settings shows one
"Standing-rule confidence threshold" control where it showed three.

Operator ruling (2026-10-05): one shared bar for the rule arms, "especially
since we're only taking the first x number of them" -- the budget limits
what is shown; the bar only decides what is worth ranking. Kept a dial.

Why 0.70, from records read rather than percentiles:
- write_path_rule near-misses at 0.7199-0.72 were all false positives
  (rule 149 against a Lidarr comment, 157 against a retention Svelte file,
  121 against an Archives restore, 164 against a config test, 131 against a
  Go package), so the old 0.72 was not hiding real hits -- but the band does
  noise control on this arm, so dropping 0.02 costs little.
- prompt_rule: the operator set 0.70 by hand on 2026-09-18, after a 0.60
  experiment admitted junk and was reverted. 0.70 is the number with a human
  decision behind it.
- pre_tool_rule lines near 0.68 this session were mostly noise; rising to
  0.70 trims them, and the band still narrows what clears.

Retired keys: kb_promptrule_threshold, kb_toolrule_threshold and
kb_rulehint_threshold are no longer read. Rows an install stored under them
stay in the settings table, inert. On this instance the effective bars move
pre_tool_rule 0.68 -> 0.70, write_path_rule 0.72 -> 0.70, prompt_rule stays
0.70; record_release_defaults writes those per-surface release rows on boot,
so the telemetry shift has an event to explain it.

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

src/grimoire/services/retrieval_tuning.py

@@ -44,6 +44,7 @@ from grimoire.services.retrieval_surfaces import (
     budget_for,
     floor_for,
     get_surface,
+    sharing_floor,
     surface_names,
 )
 from grimoire.services.settings import set_setting
@@ -257,6 +258,10 @@ async def set_dial(
             "reason": text, "actor": actor, "unchanged": True,
         }
 
+    # A shared floor moves every surface that reads it, and each one's history
+    # has to show the move, or its telemetry changes with no event to explain it.
+    moved = sharing_floor(surface) if dial == "floor" else [surface]
+
     await set_setting(user_id, key, stored)
     async with async_session() as session:
         # Stamped with the space this number was chosen in. Read at
@@ -264,12 +269,13 @@ async def set_dial(
         # the caller recording it are the same call, so there is no window in
         # which they could disagree.
         stamp = calibration_stamp()
-        session.add(RetrievalTuningEvent(
-            user_id=user_id, surface=surface, dial=dial,
-            old_value=old, new_value=applied, actor=actor, reason=text,
-            embedding_model=stamp["embedding_model"],
-            shape_version=stamp["shape_version"],
-        ))
+        for name in moved:
+            session.add(RetrievalTuningEvent(
+                user_id=user_id, surface=name, dial=dial,
+                old_value=old, new_value=applied, actor=actor, reason=text,
+                embedding_model=stamp["embedding_model"],
+                shape_version=stamp["shape_version"],
+            ))
         await session.commit()
 
     return {
@@ -286,6 +292,9 @@ async def set_dial(
         # Always present, both ways round: a caller that has to test for the
         # key's absence to learn the answer will eventually forget to.
         "unchanged": False,
+        # The other surfaces this move carried with it: a shared floor is one
+        # number, and a caller tuning one rule arm has tuned them all.
+        "moved_with": [n for n in moved if n != surface],
     }