Prevent implicit global remediation tasks when scope identity is missing

[witbrock]

Merge decision: ready — a namespaced critique with no user or organisation identity can no longer silently create a globally visible remediation task.

User outcome

Retain the critique and report a recoverable routing failure when missing identity would otherwise produce an unscoped task. The investigation found a real remediation task created with null identity fields and empty publication scope edges, linked to a namespaced critique with null user/org components.

Material changes

Add a narrow check immediately before new task creation. Reuse the existing failure receipt with remediation_task_scope_identity_missing; normal routing can retry when explicit identity is supplied. Namespace text is not converted into authority. This restriction addresses the demonstrated publication leak: read-back after global publication cannot reliably undo exposure, while retaining the critique preserves recovery.

Native assignment: #V#task_agent_9bea2c2283720d92f37b0ca4047f53f5. Target-specific evidence and controller correction instructions are retained in the worker result, outside the public repository.

Evidence

pdm run pytest tests/backend/test_episode_critique_routing_service.py -q — 4 passed. The nearest faithful routing service path verifies missing identity causes no creation, the reason is persisted, explicit identity restores scoped task creation inputs, existing task/Jira reuse works, and memory-only outcomes remain available. git diff --check passed.

Ship boundary

• Minimum ship criteria: prevent the observed implicit global creation and preserve routing recovery and existing scoped behaviour; required CI passes.
• Stop-ship conditions: missing identity still creates a task, or normal identity-bearing routing regresses.
• Non-blocking observations: the historical producer revision was not retained. This does not establish where identity was first lost. Existing task scope correction requires the controller's governed preview, fingerprint, authority checks and canonical read-back; the worker cannot perform canonical mutations.
• Non-goals: infer identity from namespace, bulk backfill, change publication semantics, repair adjacent Jira routing, or deploy this revision.