feat(ledger): the consumer map surfaces — every css row carries used_by on list_shapes, flag="unused-css" (the map's negative space, surfaced never deleted), derive groups and the write-path family carry consumers, the derive line says "used by N template(s)", coverage payload unused_css + the standing block; docs, SKILL, plugin 0.1.44; the two step-2 tests expected 5 edges where fan-out makes 6 (milestone 302 step 3, #2936)

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

src/scribe/mcp/tools/shapes.py

@@ -116,10 +116,17 @@ async def list_shapes(
             classify it: instance if it should use the canon, variant with
             the why if deliberate); "recheck": judged instances/variants
             whose body changed since judged (the judgment stands; confirm
-            it again with classify_shapes, or re-judge).
+            it again with classify_shapes, or re-judge); "unused-css"
+            (milestone 302): live css rules no file's markup names — a
+            deletion candidate to look at, never auto-deleted (the map reads
+            templates only; a class built at runtime is invisible to it).
 
     Returns {"shapes": [...], "total": N} — total counts every match, not
-    just this page. Each row's `classified_by` says who judged: agent /
+    just this page. Every css row carries `used_by` {count, paths} — the
+    files whose markup names its class (milestone 302, the CSS consumer
+    map: a scoped rule is used by its own template; a shared recipe by
+    many; a count of 0 is "no template names it"). Each row's
+    `classified_by` says who judged: agent /
     audit / import are judgments; `mechanical` is the canonical stamp the
     sync applies; `hook` is write-path EVIDENCE (#2791) — the session pulled
     a snippet and then wrote code referencing/resembling it, so the shape
@@ -145,10 +152,12 @@ async def list_shapes(
         include_vanished=include_vanished, limit=limit, offset=offset,
         proposal=proposal, flag=flag, uses=uses,
     )
-    return {
-        "shapes": [r.to_compact() if compact else r.to_dict() for r in rows],
-        "total": total,
-    }
+    shapes = [r.to_compact() if compact else r.to_dict() for r in rows]
+    used_by = await shape_ledger_svc.used_by_map(rows)
+    for row, out in zip(rows, shapes):
+        if row.id in used_by:
+            out["used_by"] = used_by[row.id]
+    return {"shapes": shapes, "total": total}
 
 
 async def classify_shapes_by_rule(
@@ -295,7 +304,10 @@ async def refresh_pattern_coverage(project_id: int) -> dict:
     Returns the accounting payload — total, accounted, counts by status,
     unclassified, repos, largest_gaps, `proposed` (canon proposals awaiting
     confirmation), `derive_groups` (the biggest repeats-with-no-canon
-    families), `derive_new` (copies that joined a family since the previous
+    families, each css one with `consumers` — the files whose markup
+    render it, milestone 302), `unused_css` (css rules no template names;
+    None where the map has no evidence of templates), `derive_new` (copies
+    that joined a family since the previous
     refresh — the drift to act on now: derive the canon, don't queue an
     audit), `proposer` (what this refresh examined) — plus
     `pattern_coverage`, the same one-line summary enter_project carries.