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>

plugin/skills/shape-accounting/SKILL.md

@@ -34,6 +34,23 @@ row carries a status:
    nothing. Rows, never prose — a consumer list in a note or verification
    detail cannot be sorted, queried, or diffed.
 
+## Rows that arrive on their own
+
+Two feeds keep the ledger current between your batches, so most shapes never
+need a hand judgment:
+
+- **The sync** stamps a snippet's own reference location `canonical`
+  (`classified_by: mechanical`).
+- **The write path** stamps instances as you work: when you `get_snippet` a
+  canon and then Write/Edit code that references or resembles it, the
+  definitions being written land as `instance` rows (`classified_by: hook`,
+  the evidence in `reason`), and the prior-art hook tells you what landed
+  ("Shape accounting: recorded at … → instance of #N"). Offered-but-unopened
+  snippets stamp nothing — so *pull the canon you are instantiating*; that
+  pull is what turns your reuse into accounting. A hook row is evidence, not
+  judgment: it never overrides a classification you made, and a
+  `classify_shapes` call overrides it.
+
 ## The derive-first rule
 
 N same-shaped occurrences matching **no** recorded canon is never N loose