Covers the 9 scenarios from the §6.3 plan brief, mapped to the harness's
sessionless reality:
- client propose refuses without a session and does not write fields
- rescheduleCardAction refuses a Done card with 'Card is done'
- foreign-client propose path: PocketBase read rule denies the cross-tenant
lookup (anti-enumeration per access.ts:57-59)
- accept/dismiss/returnToScheduled refuse without a session and are no-ops
- buildActivityRows collapses same-date patches into zero rows and emits one
row when the date actually changes
HARNESS-LIMIT: the actions that need an owner session (accept, dismiss,
returnToScheduled) cannot be driven successfully in vitest. They are
covered by the manual smoke checklist at the workspace path. The
sessionless refuse path proves the gate fires for every call; the
positive path is exercised by the live smoke run.
Test file: tests/integration/plan-puzzle.test.ts (single new file)
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