access-engine/workplans/FLEX-WP-0035-per-identity-application-readback.md

id	type	title	domain	repo	status	owner	topic_slug	created	updated	related	state_hub_workstream_id
FLEX-WP-0035	workplan	Per-identity application access readback and readable protected-system registry for user-engine	infotech	access-engine	active	claude	netkingdom	2026-10-09	2026-10-09	USER-WP-0026 USER-WP-0028	cb9755fa-6824-5288-81c4-3aa2fbff1a9f

user-engine (message f1637c32, 2026-10-09, routed by net-kingdom 19a0cbcd) needs to show a signed-in person which applications they can use. Its USER-WP-0026-T03 and USER-WP-0028-T02 are blocked_on access-engine. The PEP stance is already fail-closed: no decision renders unavailable, and allow is never inferred from membership, platform role, registration, or a missing record.

What exists today (2026-10-09 review)

• POST /v1/batch_check takes several resources in one call and returns one decision per resource, each with a lifetime (expires_at) per the decision envelope. Shape-wise this is close to request (1).
• Caller auth authorizes the caller token against every resource.system in the batch (cmd/flex-auth/main.go, /v1/batch_check). The flex-auth-user-engine caller is bound to its own protected system, so a readback across other systems is a 403 today. That is correct behaviour for enforcement, and the reason this needs design rather than a config change.
• There is no generic "may use this application" action. Each package has its own action vocabulary, so "access to system X" has no defined meaning yet.
• There is no registry read endpoint. The protected-system registry is loaded from files and never served.

Define the readback contract

id: FLEX-WP-0035-T01
status: done
priority: high
state_hub_task_id: "0585a684-d462-5caa-937f-b1730efddbd8"

Decide the action that a readback evaluates per system: a declared application.access action each consumer package must opt into, versus a per-system mapping held in the registry. A system that declares nothing is returned as not_applicable, never allow. State per input class the revocation-visibility deadline the readback carries (§9.7). Decide whether the readback is a decision for audit purposes (decision record, emission) or an explicitly non-enforcing advisory read. A displayed allow must not be usable as a PEP decision by another system.

Gate: written contract in docs/ plus an ADR or decision record; reviewed with user-engine before code.

2026-10-09: user-engine accepted the contract (message f54df082) with three amendments, now folded in: the /v1/check subject shape with tenant, the rendering table, and a separate USER_ENGINE_READBACK_TOKEN_FILE. Also added: a realm-level-claims-only rule. FLEX-DEC-2026-019 is accepted.

2026-10-09: activated by the founder. Draft contract docs/application-access-readback.md and FLEX-DEC-2026-019 (proposed). Key finding: each pin loads one consumer's package, so no existing pin can answer across applications. The draft proposes a dedicated readback pin with multi-package mode, a purpose: "readback" binding that keeps decisions non-transferable, and a new optional client_binding manifest field. Sent to user-engine with four review questions. The gate closes on their reply.

Caller authorization for cross-system readback

id: FLEX-WP-0035-T02
status: done
priority: high
depends_on: [FLEX-WP-0035-T01]
state_hub_task_id: "eb0b6a91-7750-553b-b87f-c4262eb9df07"

Add a distinct caller capability (readback scope) instead of widening the flex-auth-user-engine binding to other systems' check rights. The readback caller must not be able to obtain a decision that another system's PEP would accept, and its decisions must say so in the binding.

Gate: tests prove a readback-scoped token gets 403 on /v1/check for a foreign system and is admitted only on the readback route.

2026-10-09 done. flex-auth serve-readback is a separate subcommand that mounts no /v1/check or /v1/batch_check (404 there). --readback-caller is bound under the non-system key application-readback. CheckRequest.purpose is hashed into request_digest, submitted_request_digest and approval_binding_digest, but only when set, so enforcement digests are unchanged. /v1/check refuses a request that carries it. Tests: cmd/flex-auth/readback_test.go (TestReadbackPrincipalCannotCheckOnEnforcementPin, TestReadbackHTTPCallerAndRequestShape, TestReadbackWithholdsUncommittedAllow) and pkg/api/purpose_test.go.

Readable protected-system registry

id: FLEX-WP-0035-T03
status: done
priority: medium
depends_on: [FLEX-WP-0035-T01]
state_hub_task_id: "5dbb3280-8490-58a5-a0bb-f3883e568f58"

Serve a read-only projection: system id, display name, key-cape client binding. Include the registry-snapshot digest so the catalogue is tied to the same snapshot that decisions record (G1, FLEX-WP-0019). Grants and revocations stay inside access-engine; user-domain admins get no grant surface from this work.

Gate: endpoint plus schema, admitted only for the readback caller, tests.

2026-10-09 done. GET /v1/readback/systems; optional client_binding on protected_system_manifest. Schemas readback_request, readback_response and readback_systems are checked against live service output (TestReadbackShapesMatchSchemas). schemaguard gained maxItems for this.

informed-decision declares application.access

id: FLEX-WP-0035-T05
status: wait
priority: high
blocked_on: message-from:informed-decision
blocking_reason: "Source side done; informed-decision must agree to lifecycle v2 (its own lifecycle pin will run the same digest at the next rollout)."
state_hub_task_id: "701cbd99-1a84-5290-8f66-15fa7f407d3b"

informed-decision is the first participant. Its informed-decision.lifecycle package reads authentication_audience, which the readback must not use (contract §3). Add an application.access rule over realm-level claims only, as a new package version with fixtures. Coordinate the version bump with informed-decision, because its own pin must run the same digest. Add client_binding to its registry entry.

Gate: package valid with allow/deny fixtures, informed-decision agrees, and the rule reads no audience, authorized-party or client-scoped claim.

2026-10-09 source done. informed-decision.lifecycle is now v2 (sha256:da01e045…, pin.json updated). It adds application.access, which requires purpose == "readback" and the existing human bar: net-kingdom-admins, KeyCape AAL2 pwd+otp within 12h, platform tenant. It has no workload path and reads no audience or client-scoped claim. v1's twelve operations are unchanged. Eight Go cases cover it, plus a fixture showing that it denies without the readback purpose. The catalogue examples/application-readback/ binds informed-decision to https://kc.coulomb.social / informed-decision-approver. TestReadbackInformedDecisionCatalogue proves the readback over the shipped files. The live lifecycle pin still runs v1 (image bdac62bc) until the T04 rollout. Waiting on informed-decision's agreement.

Deploy the readback pin

id: FLEX-WP-0035-T04
status: wait
needs_human: true
depends_on: [FLEX-WP-0035-T05]
blocking_reason: "Live pin change on railiance01 needs founder go."
priority: medium
state_hub_task_id: "82a8a7e6-54e9-5262-a271-24ce2f161362"

Add values/flex-auth-application-readback.yaml (or a deploy manifest) for a dedicated flex-auth-application-readback pin, plus a test asserting that its package paths match each participant's own pin values (digest-equality, §4). Add the user-engine ingress rule, then get the founder's go for the rollout.

Promised to user-engine (reply to d7e02758, 2026-10-10), so the values file must match: URL http://flex-auth-application-readback.flex-auth.svc.cluster.local.:8080 (trailing dot, in-cluster only), caller token audience flex-auth (serve-readback --caller-audience default), readback caller system:serviceaccount:user-engine:user-engine. The pin ships with the image that contains serve-readback. Hand user-engine the evidence that unblocks USER-WP-0026-T03.