M4: a before-interceptor returning #{ allowed: true, data: ... } rewrites the
value actually written (threaded through the chain; each hook sees the prior
transform), size-capped at MAX_JSON_MATERIALIZE_BYTES. Delete never transforms.
M3: an 'after' phase interceptor runs once the write has committed, with the
write's result in its payload. After-hooks observe/deny but CANNOT roll back —
a deny surfaces as an operation error while the write persists (documented at
the call site).
Adds phase authoring end to end: a [[interceptors]] entry gains phase =
before|after (default before), threaded through the plan wire, BundleInterceptor,
validate (phase in {before,after}), the reconcile diff/insert/prune key
(service/op/phase), and the repo (insert/delete/list_for_owner/list_on_app_chain,
+ the marker's phase). run_before now returns the transformed value; run_after is
new; both share one fail-closed per-entry runner. Pinned by two journeys: a
before-hook transforms the stored value, and an after-delete hook sees
result==true, denies, yet the key stays deleted.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>