Deferred review findings from PR #9466: refactor: anchor rewind mapping to stable prompt identity

Verified review findings from PR #9466 by yiliang114 whose fixes lie outside that PR's footprint, deferred by the autofix loop for follow-up. cc @yiliang114. Each rc: item links back to its original review comment. A maintainer or the PR author can turn any item into its own issue/PR and apply the ready-for-agent flow to that issue — nothing here is scheduled automatically.

• ic:5582642849 packages/cli/src/nonInteractive/session.ts: Verified real: the headless -p session starts promptIdCounter at 0 per process (session.ts:80,146-147), so a headless resume chain persists duplicate promptIds and identity lookup fails closed to the positional walk (consequence eliminated: the walk answers identically on both arms, no new refusal). The fix (seeding the counter from persisted ids) lives in a file this PR's diff does not touch (0 lines, verified via git diff origin/main...HEAD), and the PR deliberately withdrew three earlier se