Deliver validated compact capsules on provider handoff

[gioabreu]

Outcome

Make the app-owned successor task receive the deterministic repository capsule and unsynchronized delta without replaying raw transcripts.

Acceptance criteria

• Safely load and validate the approved repositorys .continuity package
• Reject oversize, secret-bearing, transcript-bearing, traversal, and unsafe-symlink inputs
• Show the capsule digest and bounded preflight before handoff
• Supply the capsule only to the first destination turn and keep source identity immutable
• Label provider output advisory and prevent it from expanding authorization
• Add deterministic and live read-only handoff evidence

Linear: OU-136
Continuity idempotency key: cross-tool-continuity:WS-005:github

[gioabreu]

Implementation progress is available in PR #7: deterministic capsule validation, bounded Git checkpoints, immutable boundary revalidation, first-turn read-only enforcement, and one-time compact handoff delivery. This issue remains open for its unchecked acceptance criteria.

[gioabreu]

Implementation is complete through deterministic integration and independent review in PR #7 at commit 56437a6. Static and runtime gates now cover package validation, 32 KiB capsule bounds, secret/transcript/path rejection, immutable provider identity, exact-boundary revalidation, one-time first-turn delivery, read-only reviewer enforcement, and advisory provider output. Verification: 134 tests passed (1 opt-in live smoke skipped), release build passed, and public CI passed. The final unchecked criterion is intentionally shared with #3: a full live app-owned successor/reviewer run, beyond the already-passing direct provider transport smoke.