Why: The approved U5 scope needs the action half of the loop: an
idempotent ledger (migration v24), a single-choke SubmitAction (plugin
activation, current-revision, action whitelist, params-hash
idempotency), dispatch through the command bus so DangerHigh lands on
the existing inline confirm card with no Confirmed passthrough (the
endpoint does not even bind the field), the button-only
generative-ui.submit storing form data in the plugin KV ledger, and
catalog discipline rejecting unknown action ids at present time.
Evidence: go build/vet clean; full go test ./... green; surfacesvc/
genui/store suites also green under AGENT_PG_TEST_DSN; red matrix
covers disabled/stale-revision/cross-owner/unknown-action/idempotent
same-and-different-params/danger-high-await-confirm and the endpoint
forged-confirmed case.
Impact: Additive migration v24 + new endpoint/command; existing
endpoints and command semantics untouched (B-class whitelist starts
empty per the approved scope).
Refs: U5 action-scope r2 (approved, Documents #71); UI #46/#47;
Frontend #56; Dev task feature/generative-ui-u5
Why: Generative UI proposal U2 needs the host side of the contract:
owner-isolated surface storage with revision CAS, an execution-level
enable/disable ledger (default-off, epoch bumped on every transition so
in-flight submits after a disable are rejected), a single-choke-point
service that validates specs (strict decode + catalog rules) before
saving, event publish with pending recovery, the optional SurfaceHost
extension capability, and direct API endpoints that share the same
guard (no bypass by entrance).
Evidence: go build/vet clean; full go test ./... passes (SQLite);
surface store tests also pass under AGENT_PG_TEST_DSN (PostgreSQL);
surface.txt regenerated via the AST snapshot test.
Impact: Additive migration v22 (new tables only); existing endpoints and
plugin_grants semantics untouched; old consumers unaffected. U3+ (data
binding, actions, frontend) deliberately out of scope.
Refs: Documents proposal 2026-10-10-generative-ui-plugin.md (r2 U2);
Core PR #25; Dev task feature/generative-ui-u2