[process-gap](state-manager+story-writer): sprint-state.yaml vp_traces field has no documented owner; stale value propagates downstream

**Severity:** MEDIUM
**Agent owners:** state-manager + story-writer

## Evidence

- S-6.06 story v1.1 changelog explicitly dropped VP-048 from vp_traces (frontmatter: `vp_traces: []`). Reason: S-6.07 owns VP-048 row 4.
- sprint-state.yaml:454 still showed `vp_traces: [VP-048]`. The orchestrator's downstream dispatches propagated the stale value.
- Adversary Pass-1 lens-3 F-001 (CRITICAL) caught it.
- Neither state-manager's contract nor story-writer's contract scopes "if story vp_traces changes, propagate to sprint-state.yaml record."

## Recommendation

codify ownership: story-writer or state-manager must own bidirectional vp_traces sync. Add a property check (consistency-validator) confirming `story.frontmatter.vp_traces == sprint-state.stories[id].vp_traces` for every story.

Source: switchboard-blue Wave-5 S-6.06 Pass-1 lens-3 F-001