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>

tests/test_shape_ledger.py

@@ -380,6 +380,17 @@ def test_proposal_summary_ranks_body_identical_groups_first_and_sees_scoped_rows
         row("v/J.vue", "closed-msg", "dup:abc", status="exempt"),
     ]
     out = proposal_summary(rows)
+    # Milestone 302: with consumer paths in hand, each css group says what
+    # renders it — distinct files across the members; absent otherwise.
+    assert "consumers" not in out["derive_groups"][0]
+    for i, r in enumerate(rows):      # unsaved rows have no id; give them one
+        r.id = i + 1
+    cpaths = {rows[0].id: ["v/0.vue", "v/Z.vue"], rows[1].id: ["v/1.vue"], rows[2].id: ["v/0.vue"]}
+    with_c = proposal_summary(rows, consumer_paths=cpaths)
+    badge = next(g for g in with_c["derive_groups"] if g["group"] == "name:css:status-badge")
+    assert badge["consumers"] == {"count": 3, "paths": ["v/0.vue", "v/1.vue", "v/Z.vue"]}
+    dup = next(g for g in with_c["derive_groups"] if g["group"] == "dup:abc")
+    assert dup["consumers"] == {"count": 0, "paths": []}
     assert [g["group"] for g in out["derive_groups"]] == ["dup:abc", "dup:def", "name:css:status-badge"]
     assert out["derive_groups"][0]["files"] == 3 and out["derive_groups"][0]["size"] == 3
     assert out["derive_groups"][0]["label"] == "closed-msg (identical body)"
@@ -455,7 +466,7 @@ def test_resolve_consumers_prefers_the_own_file_and_fans_out_for_shared_names():
         (1, "v/A.vue"): 2,            # own row, not B's
         (3, "v/A.vue"): 1,            # the shared sheet
         (2, "v/B.vue"): 1,            # own row
-        (2, "v/C.vue"): 1,            # C defines nothing → the other file's row
+        (1, "v/C.vue"): 1, (2, "v/C.vue"): 1,   # C defines none → every other definition
         (4, "v/C.vue"): 3, (5, "v/C.vue"): 3,   # ambiguous: both, not a guess
     }
     # Unknown tokens and an unreferenced row leave no trace.