Remediate the MEDIUM backend correctness/perf findings from the 2026-07-11 audit.
B1 — a group cron template toggled disabled→enabled no longer re-fires every
descendant's cron. Materialization now KEEPS a disabled cron template's copies
(syncing `enabled` in place) instead of delete+recreate, preserving
`last_fired_at`; the scheduler already skips disabled copies, so keeping them is
inert. Queue/email arms still delete-on-disable (freeing the one-consumer slot).
B2 — `rematerialize_stateful_templates` warnings are now logged at the
app-create/delete and group-reparent chokepoints (were silently dropped); only
the `Err` arm was handled before.
B3 — the group KV/docs byte-quota check skips the O(rows) `SUM(octet_length(..))`
scan when a cheap upper bound (`rows_after * max_value_bytes`) is already under
the cap, so the full aggregate only runs near-cap. Every row is validated
≤ max_value_bytes, so the bound is sound (never lets an over-quota write through).
B6 — the in-process SSE broadcaster caps live channels per map
(`PICLOUD_REALTIME_MAX_CHANNELS`, default 100k); a subscribe that would open a
NEW channel past the cap is refused with 503 + `Retry-After: 1` rather than
growing the (app,topic)/(group,topic) maps unboundedly. Check+insert is atomic
under the map mutex (no TOCTOU); an existing-channel subscribe is exempt.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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