Message stream appends are accepted on read-only Waterline v1 projections #769

Published Server 2.11.1 accepts a message stream append to a read-only Waterline v1 projection.

Behavior. POST /api/workflows/{workflowId}/message-streams/{streamName}/messages (MessageStreamController::append, MessageStreamService::append) never checks whether the instance's current run is a Waterline v1 projection (import_source = waterline_v1_projection). For a projection in an open status (pending, running or waiting), a valid append:

• creates the inbound stream and item;
• delivers a signal with its command and history event;
• creates a workflow task for a run whose execution is owned by the v1 runtime.

An invalid body still records malformed-input state on the projection's stream.

Why it matters. Every other run operation refuses a projection with v1_projection_read_only before reading its body (WorkflowController::rejectProjectedV1Operation / projectedV1OperationResponse: signal, query, update, cancel, terminate, repair, archive, redrive). The append path breaks the projection's read-only, no-tasks contract, and gives workers an execution path into a v1-owned run.

Expected. The append is refused with 409 v1_projection_read_only before the body is parsed. The service also checks under its lock, so a direct call cannot write any stream, item, signal, command, history, task or summary state. Malformed input is not counted against a projection.

Native. Server #768 (Rust #325) adds that refusal at the route and the service, plus a locked check in the store transaction. Its tests show valid and invalid appends, a direct service call and a direct store call change no rows. That will differ from published 2.11.1 until PHP is fixed.

Found by Security's review of #768. Handed to the General owner for the PHP fix.