PR #TBD — Native Sessions Can Prove Cross-Harness Review Provenance

The goalpost we inherited

The previous provenance recovery work kept synlynk pr check fail-closed when a dispatched implementation lost its cost row. The remaining gap was a legitimate implementation authored directly from an interactive home session, where no dispatch job exists to identify the implementer.

The problem this PR addresses

The cross-harness review gate only knew how to resolve implementation identity through dispatch jobs: capability ratings, linked issues, or a dispatch branch. Native sessions therefore failed the gate even when the PR had a recorded cost entry and a valid cross-harness review.

What shipped

• cost_entries now records an optional pr_number, with additive migration support for existing databases.
• synlynk cost log --pr <pr-number> --harness <harness> records native implementation provenance without reusing the categorical dispatch_context field.
• synlynk pr check uses the newest matching native cost entry only after all existing job-based paths fail, while preserving the same identity and incomplete-provenance checks.
• The missing-provenance hint and CLAUDE.md now distinguish native --pr logging from dispatched --job-id logging.

Verification

The focused database, CLI, and cost-ledger suites pass: 310 tests passed and 1 was skipped before the final persistence assertion was added. Coverage includes matching native provenance, mismatched PR numbers failing closed, and all three existing job-based recovery paths remaining green.

New goalpost

Interactive home sessions can now participate in the same measured, cross-harness review gate as dispatched work, without weakening fail-closed behavior for unrecorded or incomplete provenance.