feat(ledger): write-path stamping — a pulled canon the session then instantiates lands as a hook instance row (#2791, milestone 294 step 5)

The prior-art hook now names the shapes being written (shapes=kind:name —
every definition in the payload, or the one enclosing an Edit found by
walking the file upward) and the server stamps them as instance rows when
the session PULLED a snippet inside PULL_WINDOW that the payload references
by symbol or that the semantic arm scored for this very payload.
classified_by=hook, evidence in reason; never overrides a judgment or a
canonical row, overridable by classify_shapes. Offered-but-unopened stamps
nothing. Pulled-and-already-seen snippets stay in the semantic query as
evidence without re-entering the deduped menu. A brand-new shape gets a
provisional row the next sync confirms or vanishes. Read-scoped keys get
the hint, never the stamp. Plugin 0.1.34.

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

src/scribe/mcp/tools/shapes.py

@@ -77,10 +77,17 @@ async def list_shapes(
         limit/offset: page through big ledgers (limit caps at 500).
 
     Returns {"shapes": [...], "total": N} — total counts every match, not
-    just this page. Classify what you can judge with classify_shapes; a
-    repeating shape with NO recorded canon is a derive-one-first moment
-    (consolidate onto a reference, create_snippet it, then classify the
-    rest against it), never N loose classifications.
+    just this page. 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
+    was stamped an instance with the evidence in `reason`. A hook row is
+    overridable by any classify_shapes call; it never overrides yours.
+
+    Classify what you can judge with classify_shapes; a repeating shape
+    with NO recorded canon is a derive-one-first moment (consolidate onto a
+    reference, create_snippet it, then classify the rest against it), never
+    N loose classifications.
     """
     uid = current_user_id()
     rows, total = await shape_ledger_svc.list_project_shapes(

src/scribe/routes/plugin.py

@@ -127,6 +127,15 @@ async def write_path_prior_art():
                              surfaced. A separate channel on purpose: a reuse
                              hint shown early must not suppress the record-sync
                              nudge when the recorded file is edited later.
+        shapes (opt)       — comma-separated `kind:name` definitions the hook
+                             found in (or enclosing) the payload, kind being
+                             css|sym. The shape ledger's write-path feed
+                             (#2791): when the session recently PULLED a
+                             snippet this payload references or resembles,
+                             these land as instance rows (classified_by=hook).
+                             Honoured only for a caller allowed to write — a
+                             read-scoped key still gets the hint, and never
+                             changes accounting on a GET.
     """
     path = (request.args.get("path") or "").strip()
     code = request.args.get("code") or ""
@@ -149,14 +158,40 @@ async def write_path_prior_art():
         int(p) for p in (request.args.get("exclude_sync_ids") or "").split(",")
         if p.strip().isdigit()
     ]
+    shapes = _parse_shapes(request.args.get("shapes") or "")
+    api_key = getattr(g, "api_key", None)
+    may_stamp = api_key is None or getattr(api_key, "scope", "") == "write"
 
     result = await plugin_ctx_svc.build_write_path_hint(
         g.user.id, path, code=code, project_id=project_id,
         exclude_ids=exclude_ids, exclude_sync_ids=exclude_sync_ids,
+        stamp_shapes=shapes if may_stamp else None,
+        repo_key=repo_bindings_svc.normalize_repo_key(repo) if repo else "",
     )
     return jsonify(result)
 
 
+# The hook names at most a dozen definitions per write; anything past that is
+# a generated file, not a shape being instantiated.
+_SHAPES_CAP = 12
+
+
+def _parse_shapes(raw: str) -> list[tuple[str, str]]:
+    """`css:btn-primary,sym:onTrash` → [("css", "btn-primary"), ("sym", "onTrash")].
+    Unknown kinds and empty names are dropped, duplicates collapse, and the
+    list is capped — the hook's own cap, re-applied so the contract holds
+    for any caller."""
+    out: list[tuple[str, str]] = []
+    for part in raw.split(","):
+        kind, _sep, name = part.strip().partition(":")
+        kind, name = kind.strip(), name.strip()
+        if kind in ("css", "sym") and name and (kind, name) not in out:
+            out.append((kind, name))
+        if len(out) >= _SHAPES_CAP:
+            break
+    return out
+
+
 @plugin_bp.get("/processes")
 @login_required
 async def process_manifest():

src/scribe/services/plugin_context.py

@@ -27,6 +27,7 @@ from scribe.services import knowledge as knowledge_svc
 from scribe.services import notes as notes_svc
 from scribe.services import projects as projects_svc
 from scribe.services import rulebooks as rulebooks_svc
+from scribe.services import shape_ledger as shape_ledger_svc
 from scribe.services import snippets as snippets_svc
 from scribe.services.access import label_shared_items, owner_names_for
 from scribe.services.embeddings import semantic_search_notes
@@ -703,6 +704,8 @@ async def build_write_path_hint(
     project_id: int = 0,
     exclude_ids: list[int] | None = None,
     exclude_sync_ids: list[int] | None = None,
+    stamp_shapes: list[tuple[str, str]] | None = None,
+    repo_key: str = "",
 ) -> dict:
     """Prior-art hint for the plugin's PreToolUse hook on Write/Edit.
 
@@ -749,9 +752,20 @@ async def build_write_path_hint(
     un-scored surfacing now has its own home: every arm emits note_usage_events,
     tagged 'write_path_sync' vs 'write_path_place' vs 'write_path_semantic', so
     each claim's pull-through rate is measurable on its own.
+
+    ``stamp_shapes`` turns the same request into the ledger's write-path feed
+    (#2791): the (kind, name) definitions the hook saw in — or enclosing —
+    the payload. When the session has PULLED a snippet recently and this
+    payload references or resembles it, those shapes land as `instance` rows
+    (classified_by=hook, see shape_ledger.stamp_write_path_instances) and
+    the result's ``stamped`` lists them. The route passes it only for a
+    caller allowed to write — a read-scoped key gets the hint, never the
+    stamp. ``repo_key`` (the hook's remote, normalised) homes a provisional
+    row for a shape the ledger has not synced yet.
     """
     cfg = await get_writepath_config(user_id)
-    empty = {"context": "", "note_ids": [], "sync_note_ids": [], "config": cfg}
+    empty = {"context": "", "note_ids": [], "sync_note_ids": [], "config": cfg,
+             "stamped": []}
     path = (path or "").strip()
     if not cfg["enabled"] or not path:
         return empty
@@ -800,6 +814,15 @@ async def build_write_path_hint(
         seen.add(nid)
         placed.append(("nearby", item))
 
+    # The stamping feed's "actually pulled it" half (#2791). Read once, before
+    # the semantic arm, because the arm's query doubles as the resemblance
+    # test: a pulled snippet this session already saw (so it sits in `seen`)
+    # must still be SCORED for this payload — it just isn't re-listed.
+    pulled: dict = {}
+    if stamp_shapes:
+        pulled = await shape_ledger_svc.recent_pulls(user_id)
+    resembles: dict[int, float] = {}
+
     # --- arm 2: by meaning ---
     scored: list[tuple[str, dict]] = []
     remaining = top_k - len(synced) - len(placed)
@@ -821,12 +844,15 @@ async def build_write_path_hint(
         query = concept_query(query) or query
     if remaining > 0 and query:
         t0 = time.perf_counter()
+        # Pulled-and-seen ids stay in the query (as evidence) but never in
+        # the menu — the dedup contract holds, the resemblance still lands.
+        pulled_seen = seen & set(pulled)
         hits = await semantic_search_notes(
             user_id, query,
-            limit=remaining,
+            limit=remaining + len(pulled_seen),
             threshold=cfg["threshold"],
             project_id=scope_project,
-            exclude_ids=seen,
+            exclude_ids=seen - pulled_seen,
             # Snippets AND recorded experience (#2246). This arm was
             # snippets-only, which is auto-inject's mistake inverted: an issue
             # saying "we tried this and it deadlocked", or a dev-log recording
@@ -845,6 +871,11 @@ async def build_write_path_hint(
             # the browse scope and never surfaces a one-to-one direct share.
             scope="browse",
         )
+        resembles = {
+            int(note.id): float(score) for score, note in hits
+            if int(note.id) in pulled
+        }
+        hits = [(s, n) for s, n in hits if int(n.id) not in seen][:remaining]
         record_retrieval(
             user_id=user_id, source="write_path", query=query,
             threshold=cfg["threshold"], limit=remaining,
@@ -879,7 +910,20 @@ async def build_write_path_hint(
                 ))
 
     menu = (placed + scored)[:max(0, top_k - len(synced))]
-    if not synced and not menu:
+
+    # The stamp runs whether or not anything is rendered — after dedup, the
+    # common case is a silent hint and a pulled canon being instantiated.
+    stamped: list[dict] = []
+    if stamp_shapes and pulled:
+        try:
+            stamped = await shape_ledger_svc.stamp_write_path_instances(
+                user_id, project_id, path=path, shapes=stamp_shapes,
+                code=code or "", pulled=pulled, resembles=resembles,
+                repo_key=repo_key,
+            )
+        except Exception:
+            logger.warning("Write-path ledger stamping failed", exc_info=True)
+    if not synced and not menu and not stamped:
         return empty
 
     owners = await owner_names_for({
@@ -943,6 +987,9 @@ async def build_write_path_hint(
         note_ids.append(int(item["id"]))
         lines.append(_prior_art_line(item, marker, owner, foreign_lang))
 
+    if stamped:
+        lines.append(_stamp_line(path, stamped))
+
     # Split by arm, which is the whole reason this table exists. The place arm
     # carries no score and so has no home in retrieval_logs; before #2085 a
     # snippet surfaced BY PLACE left no trace anywhere, making the arm that
@@ -964,9 +1011,29 @@ async def build_write_path_hint(
         "note_ids": note_ids,
         "sync_note_ids": sync_note_ids,
         "config": cfg,
+        "stamped": stamped,
     }
 
 
+def _stamp_line(path: str, stamped: list[dict]) -> str:
+    """One line saying what the ledger just recorded, so the session can
+    correct a wrong stamp in the moment rather than an audit finding it."""
+    by_snippet: dict[int, list[str]] = {}
+    for row in stamped:
+        label = f".{row['symbol']}" if row["kind"] == "css" else row["symbol"]
+        by_snippet.setdefault(int(row["snippet_id"]), []).append(f"`{label}`")
+    parts = [
+        f"{', '.join(names)} → instance of #{sid}"
+        for sid, names in by_snippet.items()
+    ]
+    return (
+        f"> Shape accounting: recorded at `{path}` — {'; '.join(parts)} "
+        "(classified_by=hook: you pulled that snippet this session and this "
+        "code references/resembles it). Not an instance? `classify_shapes` "
+        "overrides a hook stamp."
+    )
+
+
 async def _topic_titles(topic_ids: set[int]) -> dict[int, str]:
     """Map topic_id -> title for the given ids (live topics only)."""
     if not topic_ids:

src/scribe/services/shape_ledger.py

@@ -21,13 +21,17 @@ an extracted shape.
 """
 from __future__ import annotations
 
-from datetime import datetime, timezone
+import logging
+import re
+from datetime import datetime, timedelta, timezone
 
 from sqlalchemy import select
 
 from scribe.models import async_session
 from scribe.models.code_shape import CodeShape
 
+logger = logging.getLogger(__name__)
+
 # Statuses whose meaning requires a snippet target.
 _NEEDS_TARGET = ("canonical", "instance", "variant")
 
@@ -408,3 +412,187 @@ async def snippet_consumers(user_id: int, note_id: int) -> dict:
             _consumer_dict(row)
         )
     return out
+
+
+# --- write-path stamping (#2791): hook evidence lands as rows ----------------
+#
+# The write-path hook (plugin/hooks/scribe_prior_art.sh) fires on every
+# Write/Edit and already carries the two halves of a consumer-map row: the
+# file being written and the definitions in (or enclosing) the payload. What
+# it could not say on its own is WHICH canon the session is instantiating.
+# The pull stream answers that: a snippet the session opened in full
+# (get_snippet) and is now writing code that references or resembles is being
+# reused — and a reused canon's call site is an `instance` (note 2786).
+#
+# The rule, deliberately two-sided so it cannot fire on noise:
+#   PULLED   — a PULLED usage event by this user inside PULL_WINDOW. Offered-
+#              but-ignored (surfaced, never opened) stamps nothing.
+#   IN PLAY  — the payload references the snippet's symbol by name, or the
+#              semantic arm scored it above the write-path threshold for this
+#              very payload. Either is evidence; the pull alone is not.
+# Both hold → every shape the hook named at that path, of the snippet's kind,
+# becomes instance-of-N with classified_by="hook" and the evidence as reason.
+#
+# A hook row is EVIDENCE, not judgment: it only ever lands on rows nobody has
+# judged (unclassified) or rows an earlier hook stamped, never on a canonical
+# row or an agent/audit/import judgment. Re-judge with classify_shapes.
+
+# "The write path actually pulled it": a working session's reach. The
+# precision comes from the in-play test above, not from this window.
+PULL_WINDOW = timedelta(hours=6)
+
+def snippet_kind(symbol: str, language: str) -> str:
+    """The ledger kind a snippet's reference belongs to — "css" when its
+    symbol is a class selector (or it is a stylesheet with no symbol),
+    else "sym"."""
+    sym = (symbol or "").strip()
+    if sym.startswith("."):
+        return "css"
+    if not sym and (language or "").strip().lower() in ("css", "scss", "sass", "less"):
+        return "css"
+    return "sym"
+
+
+def references_symbol(code: str, symbol: str, kind: str) -> bool:
+    """Does this payload name the snippet's symbol? Word-bounded so `confirm`
+    never claims `confirmed`; a CSS class matches as `.btn` or inside a class
+    attribute (`btn btn-primary`), dashes counting as part of the name."""
+    sym = _norm_symbol(symbol or "")
+    if not sym or not code:
+        return False
+    if kind == "css":
+        pattern = rf"(?<![\w-]){re.escape(sym)}(?![\w-])"
+    else:
+        pattern = rf"(?<![\w$]){re.escape(sym)}(?![\w$])"
+    return re.search(pattern, code) is not None
+
+
+async def recent_pulls(user_id: int, *, window: timedelta = PULL_WINDOW) -> dict[int, datetime]:
+    """{note_id: last pulled at} for every note this user opened in full
+    inside ``window`` — the "actually pulled it" half of the stamping rule.
+    Reads the usage telemetry table; an unreadable table means no evidence."""
+    from sqlalchemy import func
+
+    from scribe.models.note_usage import PULLED, NoteUsageEvent
+
+    since = datetime.now(timezone.utc) - window
+    try:
+        async with async_session() as session:
+            rows = await session.execute(
+                select(NoteUsageEvent.note_id, func.max(NoteUsageEvent.created_at))
+                .where(
+                    NoteUsageEvent.user_id == user_id,
+                    NoteUsageEvent.event == PULLED,
+                    NoteUsageEvent.created_at >= since,
+                )
+                .group_by(NoteUsageEvent.note_id)
+            )
+            return {int(nid): ts for nid, ts in rows.all()}
+    except Exception:
+        logger.warning("recent_pulls read failed — no hook stamping this write", exc_info=True)
+        return {}
+
+
+async def stamp_write_path_instances(
+    user_id: int,
+    project_id: int,
+    *,
+    path: str,
+    shapes: list[tuple[str, str]],
+    code: str,
+    pulled: dict[int, datetime],
+    resembles: dict[int, float] | None = None,
+    repo_key: str = "",
+) -> list[dict]:
+    """Land hook evidence as `instance` rows for the shapes being written.
+
+    ``shapes`` is the hook's (kind, name) list for ``path``; ``pulled`` is
+    recent_pulls(); ``resembles`` maps snippet ids the semantic arm scored
+    for this payload to their score. Returns the rows stamped, each
+    {path, symbol, kind, snippet_id, reason} — empty in the common case.
+
+    A shape the ledger has no live row for yet (it is being written right
+    now) gets a PROVISIONAL row under ``repo_key`` — first/last-seen unset —
+    so the stamp is not lost to the next sync, which either confirms the
+    shape (sets its seen marker) or stamps it vanished. No repo key → only
+    existing rows are stamped.
+
+    When more than one pulled snippet is in play for a shape, a by-name
+    reference beats resemblance and the most recent pull breaks ties: a row
+    holds one canon (the known model limit logged on #2790).
+    """
+    from scribe.services import access
+    from scribe.services import snippets as snippets_svc
+    from scribe.services.snippets import snippet_fields
+
+    resembles = resembles or {}
+    path = (path or "").strip()
+    wanted = [(k, n.strip()) for k, n in shapes if k in ("css", "sym") and n.strip()]
+    if not project_id or not path or not wanted or not pulled:
+        return []
+    if not await access.can_write_project(user_id, project_id):
+        return []
+
+    # Which pulled canons are in play for this payload, by kind, ranked.
+    in_play: dict[str, list[tuple[int, datetime, int, str]]] = {}
+    for sid, pulled_at in pulled.items():
+        note = await snippets_svc.get_snippet(user_id, sid)
+        if note is None:
+            continue
+        fields = snippet_fields(note)
+        symbol = fields.get("symbol") or ""
+        kind = snippet_kind(symbol, fields.get("language") or "")
+        if references_symbol(code, symbol, kind):
+            rank, why = 2, f"hook: pulled #{sid}; payload references `{_norm_symbol(symbol)}`"
+        elif sid in resembles:
+            rank, why = 1, f"hook: pulled #{sid}; payload resembles it ({resembles[sid]:.2f})"
+        else:
+            continue
+        in_play.setdefault(kind, []).append((rank, pulled_at, sid, why))
+    if not in_play:
+        return []
+    for bucket in in_play.values():
+        bucket.sort(key=lambda t: (t[0], t[1]), reverse=True)
+
+    now = datetime.now(timezone.utc)
+    stamped: list[dict] = []
+    async with async_session() as session:
+        rows = (
+            await session.execute(
+                select(CodeShape).where(
+                    CodeShape.project_id == project_id,
+                    CodeShape.path == path,
+                    CodeShape.vanished_at.is_(None),
+                )
+            )
+        ).scalars().all()
+        by_key = {(r.symbol, r.kind): r for r in rows}
+        for kind, name in wanted:
+            bucket = in_play.get(kind)
+            if not bucket:
+                continue
+            _rank, _at, sid, why = bucket[0]
+            row = by_key.get((name, kind))
+            if row is None:
+                if not repo_key:
+                    continue
+                row = CodeShape(
+                    project_id=project_id, repo_key=repo_key,
+                    path=path, symbol=name, kind=kind,
+                )
+                session.add(row)
+                by_key[(name, kind)] = row
+            elif not (row.status == "unclassified" or row.classified_by == "hook"):
+                continue  # a judgment — or the canon itself — stands
+            row.status = "instance"
+            row.snippet_id = sid
+            row.reason = why
+            row.classified_by = "hook"
+            row.classified_at = now
+            stamped.append({
+                "path": path, "symbol": name, "kind": kind,
+                "snippet_id": sid, "reason": why,
+            })
+        if stamped:
+            await session.commit()
+    return stamped