audit-core/workplans/AUDIT-WP-0009-evidence-role-conformance.md

id	type	title	domain	repo	status	owner	topic_slug	created	updated	depends_on	state_hub_workstream_id
AUDIT-WP-0009	workplan	Evidence-role conformance under Security Layer Model v0.7	infotech	audit-core	ready	claude	railiance	2026-08-29	2026-08-29	AUDIT-WP-0007	46a96b03-bc08-53b5-9c93-4071adabf734

AUDIT-WP-0009 — Evidence-role conformance under Security Layer Model v0.7

Goal

Make audit-core dischargeable as the estate's Evidence engine under NetKingdom Security Layer Model v0.7 (accepted), and stop it claiming a property its own contract does not permit.

Two things drive this workplan.

First, a live overclaim. audit_core/postgres_backend.py returns tamper_evidence=True as a constant, while docs/integrity.md permits that claim only when a live external chain-head attestation exists. The one attestation on record is 2026-08-16 and nothing renews it. Audit Core is currently telling every sender it has a property whose precondition is unverified — the §9.6 defect it twice corrected in gate-house's doctrine, turned inward.

Second, an obligation audit-core argued for and cannot yet support. v0.7 §9.6 makes a declared emission cadence a MUST for load-bearing sources, with reconciliation or a heartbeat as the required form for low-volume classes. audit-core raised both, moving cadence from SHOULD to MUST. A source cannot declare a cadence to a system with nowhere to put it. Having won the obligation, audit-core owes the surface.

Full assessment: history/2026-08-29-v0.7-alignment-and-scope-assessment.md. Standard: net-kingdom/canon/standards/security-layer-model_v0.7.md, companion net-kingdom/SECURITY-COMPANION.md.

Non-goals

Fixed by the statute; not deferred, not ours:

• No authorization decision surface, and no approval-validity query (§6, §9.4).
• No operative approval state (§9.4).
• No WORM, object lock, or ITC-CAP data.archive — §16 ruled the stronger-custody gap closed, a different store with a different owner.
• Emission atomicity at the source, which is the emitter's obligation (§9.6).

Tasks

id: AUDIT-WP-0009-T01
status: done
priority: high
state_hub_task_id: "f545b0e4-8c99-5186-affd-ce9a41209ed7"

Make tamper_evidence conditional on live attestation state. Derive the flag rather than hard-coding it: the backend reports True only when a chain-head attestation exists, verifies against the live chain, and is within a declared freshness window. Stale or absent attestation degrades the claim — it does not leave it standing. Assert the degradation with a test, and state the freshness window in docs/integrity.md alongside the two existing preconditions, which today are documented but unenforced.

Done 2026-09-06. evaluate_tamper_evidence in audit_core/integrity.py derives the claim from a ChainReport and the mounted attestation; PostgresAuditBackend reads it per retention_policy call through tamper_evidence_state(), briefly cached because /readyz probes it. Seven degradation reasons are distinguished and asserted — no_attestation, attestation_stale, attestation_mismatch, attestation_undated, chain_break, chain_unreadable, against attested. Unreadable is treated as absent deliberately: a malformed file must not hold up a claim a missing file would drop. The freshness window is 168h against an intended daily cadence, declared in docs/integrity.md with the reasoning that the window is seven cadences so missed runs degrade rather than flap. Twelve tests in tests/test_integrity.py; docs/audit-backend-contract.md now states the field is derived rather than declared.

Consequence to state plainly: production /readyz will report tamper_evidence: false until T02 mounts a renewed attestation. The 2026-08-16 attestation is 21 days old against a 7-day window. That is the overclaim being removed, not a regression — the claim was false before and now says so.

id: AUDIT-WP-0009-T02
status: todo
priority: high
state_hub_task_id: "6de9945f-4dd1-57dd-898a-f59c35b1df6c"

Schedule chain-head attestation so the precondition T01 enforces is normally met. attest-chain exists and is operator-run; deploy/ has no job. Add one, write the attestation to the logical-offsite path already used by RESOURCE-WP-0002-T06 (rapp-postgres / Nextcloud + age) and not the Barman prefix, per docs/integrity.md — that copy is restored with the table and proves nothing. Record the cadence in docs/integrity.md.

id: AUDIT-WP-0009-T03
status: todo
priority: high
state_hub_task_id: "acae6085-ada7-51b2-8dc0-4abac7f7e7b3"

Represent the §9.6 evidence kind per source. Add evidence_kind (load-bearing | attributive) to SenderIdentity and the sender registration schema, defaulting to attributive — a source that has not declared is not silently treated as load-bearing. Where a source declares attributive and has deliberately traded away atomicity, carry the declared trade with it, because §9.6 requires the trade be declared where the trail is documented. Prerequisite for T04–T06.

id: AUDIT-WP-0009-T04
status: todo
priority: high
state_hub_task_id: "f36470af-4019-54b2-96d7-e049d867c7db"

Heartbeat ingestion and missing-heartbeat findings. The required form for low-volume load-bearing classes, and the only control covering adversarial omission for exactly the rare negative events — revocation, denial, containment — where suppression is most valuable and least visible. Accept a signed nothing to report assertion per source and class; raise a finding when an expected heartbeat does not arrive. The point is a positive claim that can itself go missing, which rate monitoring can never produce.

id: AUDIT-WP-0009-T05
status: wait
priority: medium
state_hub_task_id: "382575ca-1801-5a32-a93d-90a8b9c8adbf"

Accept and evaluate a declared emission cadence per source, and raise a finding when the stream falls below it. Waiting on the §17 emission-cadence declaration schema, which kings-guard is drafting and Taxonomy will own; do not invent a competing shape. Cadence covers high-volume streams; T04 covers the low-volume load-bearing case, and the two are complementary rather than alternatives.

id: AUDIT-WP-0009-T06
status: todo
priority: medium
state_hub_task_id: "0a8d6eed-75dd-5aaa-bf86-60be9dadca03"

Reconciliation surface: per-source, per-class event counts over a bounded window, readable by the source itself, so an emitter can compare audit-core's count against its own state transitions and treat divergence as a finding. GH-WP-0002-T04 is the reference instance on the approval-engine side; this is its counterpart here. Respect the existing read model — may_read, tenant scoping, and no payloads in a counts response.

id: AUDIT-WP-0009-T07
status: todo
priority: medium
state_hub_task_id: "f572dfeb-0d1b-58d6-be83-405125189028"

Give stream-completeness findings a home. /v1/dead-letters and /v1/secret-findings exist; a cadence miss (T05) and a missing heartbeat (T04) have nowhere to surface. INTENT principle 10 already says a degraded audit stream is itself an audit and operations event — the principle is in place and the mechanism is not. Follow the existing findings-surface conventions rather than adding a new shape.

id: AUDIT-WP-0009-T08
status: done
priority: medium
state_hub_task_id: "f7b513ee-af48-5c5a-a34e-3e9922d29b76"

Assert the §9.4 approval-validity prohibition with a negative test. It is currently honoured by absence, which is not the estate's idiom: §6.4 obligation 3 requires a PEP's published stance map equal shipped behaviour asserted by test. A prohibition worth stating in INTENT.md, SCOPE.md, and layer.yaml is worth asserting in tests/.

id: AUDIT-WP-0009-T09
status: todo
priority: low
state_hub_task_id: "fd4a4ac3-e525-57c1-9179-e0fcd0226913"

Register approval-engine as a distinct source under §9.4 and AUDIT-IN-0001: sender registration, the four event classes (issuance, use, supersession, revocation), tenancy mapping, retention profile, secret_policy, and evidence_kind: load-bearing from T03. Onboarded under INTENT principle 4 — declared ownership, retention, access, export and evidence policy, not merely events arriving. Not blocking: approval-engine is not yet emitting.

id: AUDIT-WP-0009-T10
status: todo
priority: low
state_hub_task_id: "ac3464fd-3df9-51a1-b1f4-3bf3c60e4265"

Make the §5 conformance check total. layer.yaml declares tooling_contacts: [], true under §5 as written — audit-core is an Engine and holds no key-cape or OpenBao client. Companion §4 asks that uncatalogued infrastructure be listed anyway, and that carve-out sunsets within two review intervals for a store another layer reads, which platform-pg is. List it and the State Hub now. Add a conformance script and test in the shape ops-warden offered estate-wide.

Acceptance

• No custody claim is returned unconditionally where docs/integrity.md conditions it, and a stale attestation visibly degrades the claim.
• A source can declare its evidence kind, and a load-bearing source can discharge the §9.6 cadence MUST against a real audit-core surface.
• A suppressed low-volume load-bearing class produces a finding rather than silence.
• The approval-validity prohibition is asserted by test, not by absence.
• layer.yaml lists every infrastructure contact, catalogued or not, and a test checks it.

Notes

T01 and T02 are separable and T01 is the one that matters: scheduling attestation without making the claim conditional would leave the overclaim in place whenever the job fails, which is precisely the case the claim is supposed to cover.

T05's dependency is real and should not be worked around. audit-core argued the cadence obligation up to a MUST; inventing a local cadence shape ahead of the Taxonomy schema would fragment the very interface it asked for.