Save notice from a sandboxed hook or a flow: hook context and flow node set the write answer's notice #28251

domain:spec#2 · os-tesla · session_01L9qibx5r5nhDMwpRs4SL6D

Filing gate: ③ the server half of #28000, whose contract half lands in PR #28247 (claim 6528694653; os-dev-report 6531067088; contract review 6531609713 PASS). ⛔ Not a claim. Triage sets the lane and grade.
Reach: HotCRM sends a deal for approval on save and shows a record:alert banner as the workaround (#27380 row 3). Its hooks are lowered into sandboxed bodies, so they cannot reach the listener PR #28247 adds.

Observed (once PR #28247 is on main)

• CreateDataResponseSchema / UpdateDataResponseSchema carry notice (one non-empty string, info, last call wins, never stored), set through WriteObservabilityOptions.onNotice(message) on ctx.input.options. Only a code handler holding the write's options can call it.
• No hook-context spelling a sandboxed body can call, and no flow node sets it. Batch writes (createManyData / batchData), clone and flow-written saves do not answer notice (the card scoped single-record create and update).

Wanted

• A hook-context member a sandboxed body (and a handler the build lowers into one) can call to set the notice. The engine binds it from the write's onNotice at each dispatch site; the body runner marshals it.
• A flow node that sets the notice on the running record-triggered write.
• Contract review should-fix (a): the surface will want a translatable message (a message id plus params, or a catalog key) rather than only a plain string. Decide it here, and widen the answer key compatibly if needed.

Dedupe words: hook save notice, ctx notice, flow notice on save, sandboxed hook notice.

Links back: #28000, PR #28247, #27380.

Blocked-by: #28247