feat(shapes): a component file is a candidate shape in its own right (milestone 439 step 5)

A single-file component defines `.card`, `.title` and a `Props`, never
anything named after itself — so the ledger could not hold "StatusChip is
canon" and could not say a new card was built where one already existed.

- coverage.is_file_unit: a file that RENDERS (its markup names classes, or it
  opens a <script>/<template>/<style> block) and defines nothing named after
  its stem gets one `file` row. Structural, not a framework list: Svelte and
  Vue components qualify, a TSX component already has its function's row, a
  module is accounted for by its definitions. Emitting every file would have
  put every module of every project in the todo at once.
- No body fingerprint on file rows, so an edit never re-asks a judgment.
- `file` is its own form and family; derive grouping skips it (`index`,
  `+page` repeat by convention). Divergence buckets it on its own, so a new
  component where a component canon dominates is a fair question.
- mark_canonicals: a snippet recorded at a path with no symbol makes that
  file row canonical; it still covers no definition inside.
- The write hooks apply the same test before noting a new file for the
  end-of-turn question.

Plugin version minted.

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

src/scribe/services/shape_ledger.py

@@ -408,6 +408,11 @@ async def mark_canonicals(
     fall back to unclassified. Agent judgments are never overwritten.
     """
     usable = [(nid, p, s) for nid, p, s in recorded if (s or "").strip()]
+    # A location naming a FILE and no symbol is a whole-file record: it makes
+    # no claim about a definition inside (`location_covers`), but it is
+    # exactly the claim a `file` row asks about (milestone 439).
+    whole_files = {(p or "").strip(): nid for nid, p, s in recorded
+                   if (p or "").strip() and not (s or "").strip()}
     now = datetime.now(timezone.utc)
     async with async_session() as session:
         rows = (
@@ -426,6 +431,8 @@ async def mark_canonicals(
                 ),
                 None,
             )
+            if covering is None and row.kind == "file":
+                covering = whole_files.get(row.path)
             if covering is not None and row.status in _MECHANICAL_TODO:
                 await _judge(session, row, status="canonical", snippet_id=covering,
                              by="mechanical", reason=None, at=now)
@@ -991,6 +998,10 @@ def shape_form(signature: str, kind: str = "sym") -> str:
     """
     if kind == "css":
         return "css"
+    if kind == "file":
+        # A whole file (milestone 439): its own family, comparable only with
+        # other files — a component is never told to build from a helper.
+        return "file"
     sig = (signature or "").strip()
     if not sig:
         return FORM_UNKNOWN
@@ -1085,6 +1096,8 @@ def shape_family(form: str) -> str:
         return "value"
     if form == "css":
         return "css"
+    if form == "file":
+        return "file"
     return ""
 
 
@@ -2040,6 +2053,10 @@ async def apply_derive_groups(project_id: int) -> int:
                     CodeShape.status.in_(_MECHANICAL_TODO),
                     CodeShape.vanished_at.is_(None),
                     CodeShape.proposed_snippet_id.is_(None),
+                    # A file row is named by its stem, and `index`, `+page`
+                    # and `__init__` repeat by convention, not by copying —
+                    # a derive family of them would be pure noise.
+                    CodeShape.kind != "file",
                 )
             )
         ).scalars().all()