flex-auth/docs/decision-record-contract.md

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# Decision-record contract
Status: published
Contract: `flex-auth.decision-record.v1`
Schema: [`../schemas/decision_envelope.schema.json`](../schemas/decision_envelope.schema.json)
Date: 2026-09-02
This is flex-auth's output artifact under the NetKingdom Security Layer Model
v0.7 §17. Taxonomy holds only the shared field vocabulary. Consumers may rely
on this schema.
A decision record is a `DecisionEnvelope` returned by `POST /v1/check` and the
CLI `check` / `batch-check` / `list-allowed` commands. Standalone evaluation
and every delegated adapter (Topaz, relationship, rule, Keycloak) emit the
same shape.
## Required fields
| Field | Meaning |
| --- | --- |
| `id` | Deterministic decision identifier |
| `effect` | `allow`, `deny`, `redact`, `audit_only`, or `not_applicable` |
| `subject` / `resource` | Normalized refs the evaluator used |
| `provenance` | Who evaluated, over which policy and facts |
## Contract fields consumers may rely on
| Field | Meaning |
| --- | --- |
| `contract_version` | `flex-auth.decision-record.v1` |
| `binding` | Structured subject, action, resource, context, and `request_digest` |
Publish approval_binding_digest: a claim cannot name the request carrying it secrets-engine confirmed T03, and re-verifying against the regenerated destroy fixture found something neither repository can fix alone: a pdp_digest recorded at issue time can never equal the request_digest of a request that carries the claim in its context, because the claim is part of the context that is hashed. Embedding the claim changes the very digest the claim would need to name. Not fixture staleness. It holds for every dual-control request whose claim travels in context -- the shape GH-DEC-2026-008 had just ruled mandatory. Left unresolved that ruling was unimplementable for exactly the case it was written for, and destroy would have been permanently un-allowable in production, failing closed forever on a check that could never pass. flex-auth owns the canonical request digest, so the fix is ours. binding.approval_binding_digest is the same material with context.approval removed, emitted only when a claim was carried. An approval issued against a claim-free Check records that Check's request_digest; the claim-bearing request reproduces it here. DELIBERATELY ADDITIVE, and the reason matters. The tempting fix is to drop context.approval from request_digest entirely. That is wrong: request_digest is the replay identity, and two requests differing only in which approval was presented must not share one, because their decisions differ -- one allows, the other denies dual_control_required. Collapsing them would let an allow obtained with a valid claim be replayed against a request carrying none. So request_digest still covers the claim and still moves; approval_binding_digest deliberately does not, and is documented as not a replay identity. The tests assert the two functions DISAGREE on a claim-bearing request, which is approval-engine's formulation of how to defend a distinction that looks like duplication. The fixture now demonstrates the property rather than asserting it: its claim's pdp_digest equals the envelope's approval_binding_digest with pdp_path true, and changing the claim's contents moved request_digest while leaving approval_binding_digest untouched. Two files a consumer can diff. Also picked up approval-engine's new required binding.pdp_path via the cross-repo schema test added yesterday -- which is the test doing exactly what it was built for, one day later. T03 is done. secrets-engine's own digest-material defect, which our two real envelopes caught, is recorded in the workplan. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JTbVXpEiXA7mNJVpDnEPcB Assistant: claude-code Assistant-Model: opus Assistant-Process: 412054@bnt-lap001 Assistant-Session: 3968fae1-8d59-4209-9bd6-c22594b8ab19
2026-09-06 14:52:33 +02:00
| `binding.approval_binding_digest` | Present only when the request carried `context.approval`. The digest an approval's `pdp_digest` must equal — see [`canonical-request-digest.md`](canonical-request-digest.md). Not a replay identity |
| `lifetime` | **Required on every allow.** A TTL with `not_before` and `expires_at` |
| `provenance.policy_package` / `policy_version` | Named package pin |
| `provenance.policy_package_digest` | SHA-256 of package metadata plus compiled Rego |
| `provenance.registry_snapshot_digest` | SHA-256 of the canonical registry snapshot |
| `provenance.directory_etag` | Directory consistency token when a delegated directory was joined |
| `provenance.input_claim_digests` | SHA-256 per request-time claim class (`context`, `caring_context`) |
| `provenance.decision_time` | UTC timestamp used to compute `lifetime` |
`reason`, `diagnostics`, and CARING prose are not an authorization contract.
## Allow lifetime
Every allow carries `lifetime.kind = ttl`. The duration comes from the policy
package `allow_ttl` field, or from the engine default of `15m` when the package
omits it. A package that declares `allow_ttl: none` (or `0s`) produces a deny
with reason `allow_lifetime_unstated` instead of a standing grant.
Replay is permitted only while `lifetime.expires_at` is still in the future.
See [`canonical-request-digest.md`](canonical-request-digest.md) and
[`decision-input-freshness.md`](decision-input-freshness.md).
## Versioning
This is contract version 1. Additive optional fields may appear. Removing or
redefining a required field requires a new `contract_version` value and a new
schema id.