Declare participant I/O policy capability and realization support (API-407)

[Brad-Edwards]

Requirements

• API-407

Bounded outcome

Extend the governed participant-runtime feature-support surface so processors and backends declare participant-control policy features, guarantee strength, limitations, disclosure references, and conformance evidence.

Non-goals

• Implementing RUN-319 in a backend.
• Inferring support from method presence or adding capability booleans.
• Treating a declaration as realization evidence.

Dependencies

• Assess and design formal participant I/O control with information-flow and bisimulation semantics #794
• API-423 — Participant Crossing Policy And Evidence Contracts #798 (API-423 crossing contracts)

Acceptance criteria

• Governed feature identifiers cover ingress admission, egress projection, declassification, transformation, intervention, and participant-directed inject delivery.
• Feature-support entries use the existing strength/disclosure pattern and reject contradictions or missing required evidence.
• Target admission fails closed when a required semantic feature is unsupported; policy-authorized downgrade is explicit and cannot retain the stronger claim.
• Existing backend profiles and capability-gap diagnostics are updated without a second manifest surface.
• Update the participant section of docs/explain/sdl/lineage.md with this issue's adopted intellectual lineage, exact ACES artifact mappings, delivery status, evidence links, and explicit nonclaims; update contracts/provenance/sdl-lineage-ledger-v1.json and its source audit only when normative derivation or compatibility claims change.

Required assurance evidence

• Valid/invalid manifest fixtures.
• Capability-gap and target-admission tests.
• BackendConformanceReport cases with finite scope and explicit nonclaims.

Parent program: #794.

[Brad-Edwards]

🛠️ Picked up by /implement - branch 801-declare-participant-policy, 2026-07-17T03:30:47.606Z.

[Brad-Edwards]

gc workflow phase recorded: preflight (issue #801). Posted by the MCP server to enforce ordering between workflow steps (issue #794 MVP-2). Do not edit or delete — used by downstream tools to gate phase prerequisites.

[Brad-Edwards]

⛔ /implement paused at architecture preflight. Dependency #798 (API-423) is still open, and dev does not yet contain the published participant crossing-policy/evidence contracts or canonical contract identifiers required by #801. The preflight forbids placeholder contract IDs, temporary policy DTOs, and free-form downgrade records. Resume /implement 801 after #798 merges into dev; the isolated worktree currently contains only the generated, uncommitted preflight design note.

[Brad-Edwards]

Where appropriate, must update lineage and other documentation. Must assess prior art external to RAES to identify full/partial solves for the problem to adopt rather than re-invent.

[Brad-Edwards]

gc workflow phase recorded: preflight (issue #801). Posted by the MCP server to enforce ordering between workflow steps (issue #794 MVP-2). Do not edit or delete — used by downstream tools to gate phase prerequisites.