docs(kernel): correct the audit-write failure report granularity to once per cause

[os-try-charles]

Fixes #17451

What this changes

One bullet on content/docs/kernel/runtime-services/audit-service.mdx (the ## Typical Errors
section, lines 76-79 before this change). It described the failed ledger insert of
recordAuthEvent as reported at error level once per process, with every later failure
dropping to debug. That sentence is false on origin/main today, and the page it sits on is the
audit service's own contract documentation.

The bullet now states the granularity the runtime actually has: once per cause, a cause being
the error code plus the object the row is about. A repeat of an already-reported cause still
degrades to debug; a new cause gets its own error line, once.

Where the behaviour actually lives

Measured in this worktree at 24d622b94 (the branch point), re-read rather than inherited from the
card:

• The paragraph's subject is recordAuthEvent, whose implementation is
  packages/plugins/plugin-audit/src/auth-event-audit.ts:282 — the same file the page already
  names as its Canonical source (:7).
• The dedupe there is cause-keyed, not a process-wide boolean:
  auth-event-audit.ts:211 declares reportedAuthEventFailureCauses as a Set of cause keys (a
  Set parameterised by the string type — spelled out here rather than written literally), filled
  at :229 and read at :221. The key is built at :220 by
  auditFailureCauseKey(SESSION_OBJECT, err), with SESSION_OBJECT = 'sys_session' at :152.
• The shared key is packages/plugins/plugin-audit/src/audit-writers.ts:739
export function auditFailureCauseKey(object: string, err: unknown): string — the error's code
  when it is a string or a number, and the single bucket (no code) otherwise, joined with the
  object name.
• The runtime message this seam prints already says the same thing in words
  (auth-event-audit.ts:239-240): "this CAUSE is reported ONCE … a DIFFERENT cause gets its own
  error line". The page was the last place still describing the old unit.

⚠️ The card attributes the falsification to PR #17450 / card #15166, which re-keyed
audit-writers.ts. That is the wrong file for this paragraph: audit-writers.ts backs the CRUD
audit writers, not recordAuthEvent. The second, independent copy of the process-wide boolean —
the one this page documents — lived in auth-event-audit.ts and was re-keyed separately. The
card's conclusion holds; only its citation is corrected here.

Scope

• One file, one bullet. git diff --stat on this branch: 1 file changed, 7 insertions(+), 4 deletions(-).
• ⛔ No code changed anywhere under packages/**.
• Verified before editing: once per process occurs 1 time in this page's 114 lines (:76).
  Positive control for the query: the same phrase returns 3 further hits elsewhere under
  content/docs/ — so that 1 is a reading, not a broken pattern.

Changeset

No changeset, skip-changeset label applied. Measured rather than assumed: content/docs/ is
consumed by apps/docs, whose manifest is "private": true, and no published package in the
workspace lists a content- or docs-shaped entry in its files[]. Positive control for that
scan: published packages with a files[] array are found and printed (@objectstack/hono,
@objectstack/cli, @objectstack/client-react, …), all of them shipping dist / README.md /
CHANGELOG.md only. This diff therefore publishes nothing.

Tests

node scripts/pm/dispatch-gates.mjs --commands --repo objectstack-ai/objectstack derived 40
commands for this path; all 40 were run. See the PR's Acceptance notes below for the four that
first reported PREREQUISITE NOT MET against unbuilt workspace packages and were re-run after
building them.

Acceptance notes

• Noted, not filed here: content/docs/permissions/record-view-auditing.mdx:221 carries the
  same phrase for a different surface. It is deliberately untouched by this PR — the card fences it
  and so does the domain:services seat. It is neither excluded-because-verified nor cleared; it is
  simply out of this PR's surface, and is reported to the PM for separate triage.

---

Generated by Claude Code