Enforce task visibility across services, relationships and live updates #209
Description
Work
Apply the approved access matrix to task lists, reads, creation, patch/update, assignment, claim and completion. Visibility changes require explicit supplied fields, suitable authority and expected version. Omitted visibility in a patch preserves it. Existing write capabilities remain necessary even for public tasks.
Relationships
Children cannot be more public than ancestors; handle parent narrowing atomically or reject until conflicts are resolved. Assignments must not silently reveal a private task. Filter parent/subtask lists, backlink titles, blocker explanations, counts and readiness through task access. Live events and reloads must not leak hidden task data, including after revocation.
Acceptance
- Direct references cannot bypass visibility or project restrictions.
- Organization membership/project privacy changes affect access immediately.
- Public reads expose no hidden parent/child/assignee metadata.
- Unauthorized/partial conflicting visibility edits produce no changes.
Dependencies
#207, #208; integrate existing relations and planned ready-work behavior.