wip(394): steps 6+7 — backend path and instruction surfaces

src/scribe/services/embeddings.py

@@ -817,7 +817,6 @@ async def semantic_search_rules(
     query: str,
     limit: int = 5,
     threshold: float = _SIMILARITY_THRESHOLD,
-    tier: str | None = None,
     kind: str | None = None,
     report: dict | None = None,
 ) -> list[tuple[float, "Rule"]]:
@@ -844,17 +843,13 @@ async def semantic_search_rules(
     is the surfacing question, and it has its own machinery
     (get_applicable_rules) rather than a second, subtly different copy here.
 
-    `tier` narrows to one tier, and NONE is the ordinary case. The write-path
-    and pre-tool hints deliberately pass nothing: an always-on rule is already
-    in the session, but being in a list from turn zero is not the same as being
-    in front of the reader when the action it governs is taken, and filtering
-    on tier made a whole class of rules permanently ineligible for the one
-    mechanism that surfaces a rule AT the moment. Relevance is the threshold's
-    job; see the block above RULEHINT_LIMIT in services/plugin_context.py for
-    the argument and for what the resulting scores are being read against.
-
-    Pass a tier when a caller genuinely wants one class — a listing, an audit,
-    a UI that renders the tiers apart. Not to approximate relevance.
+    THERE IS NO TIER TO NARROW BY ANY MORE (milestone 394). This carried a
+    `tier` parameter, and the arms deliberately passed nothing: filtering on it
+    made a whole class of rules permanently ineligible for the one mechanism
+    that surfaces a rule AT the moment it applies. The tier is now gone
+    entirely, so every rule is eligible for every arm and relevance is the
+    threshold's job alone — see the block above RULEHINT_LIMIT in
+    services/plugin_context.py for what those scores are read against.
 
     `kind` narrows to `rule` or `preference`, and NONE is likewise the ordinary
     case: a caller asking "what governs this" wants both, because the reader
@@ -905,7 +900,6 @@ async def semantic_search_rules(
                         Rulebook.owner_user_id == user_id,
                         Project.user_id == user_id,
                     ),
-                    *( [Rule.tier == tier] if tier else [] ),
                     *( [Rule.kind == kind] if kind else [] ),
                 )
                 # Overfetch so collapsing chunks to their best row still fills