diff --git a/.osc/plans/backlog/178-active-open-questions-e9b7cdc8b3.md b/.osc/plans/backlog/178-active-open-questions-e9b7cdc8b3.md
new file mode 100644
index 00000000..8e95f7d7
--- /dev/null
+++ b/.osc/plans/backlog/178-active-open-questions-e9b7cdc8b3.md
@@ -0,0 +1,58 @@
+# Plan: .osc portfolio gap active-open-questions-e9b7cdc8b3
+
+<!-- osc-portfolio-gap: active-open-questions-e9b7cdc8b3 -->
+
+## Status
+
+backlog
+
+## Context
+
+The `.osc` portfolio steward detected an `active_open_questions` gap against the parent active plan text.
+
+Current source truth is narrower than the parent plan's original open-question list: amendment 1 already adds the minimal-checklist control arm, chooses the Claude-first execution lane, and defers the judge-model choice to preregistration review. This follow-up should reconcile that parent-plan/amendment drift or reject the steward finding as a stale-text false positive, not reopen all original questions as unresolved work.
+
+Source evidence:
+
+- Parent active plan: `.osc/plans/active/163-proof-harness-v2.md`
+- Amendment source truth: `.osc/plans/active/163-proof-harness-v2-amendment-1.md`
+- Resolved by amendment: minimal-checklist control arm is in; execution lane is Claude-first.
+- Deferred by amendment: Codex/OMX lane is not the first proof arm; judge-model choice is a preregistration-review decision before any scored run.
+- Narrowed gap: reconcile the parent plan's stale `## Open questions` text with amendment 1, or record that the steward gap is a false positive against current source truth.
+
+GitHub intake: #252
+
+## Goal
+
+Resolve the narrowed parent-plan/amendment drift with a small, source-grounded follow-up that keeps the public roadmap and `.osc` work record coherent.
+
+## Constraints / Out of scope
+
+- Do not merge, publish, release, dispatch workflows, change repository settings, or touch secrets from this plan alone.
+- Keep public wording owner-neutral and avoid local/private machine context.
+- Do not overclaim proof, compliance, or runtime authority.
+- If the gap is a false positive, close this plan with evidence rather than forcing implementation.
+
+## Files to touch
+
+- `ROADMAP.md` or relevant docs only if the gap requires wording/priority clarification.
+- `.osc/plans/active/*` or `.osc/plans/backlog/*` only through normal plan/amendment flow.
+- Source/test files only if a later accepted issue narrows implementation scope.
+
+## Acceptance criteria
+
+- [ ] The gap is confirmed against current `ROADMAP.md` and `.osc/plans` source truth.
+- [ ] The chosen outcome is one of: create/update a real follow-up plan, mark the older backlog entry superseded/done with evidence, amend the active plan, or reject the steward finding as a false positive.
+- [ ] Any public issue/PR comments use compact Status / Evidence / Next wording.
+- [ ] Verification commands appropriate to touched files pass before closeout.
+
+## Verification steps
+
+1. Re-run the portfolio steward dry-run and confirm this gap no longer appears, or document why it remains intentionally open.
+2. Run the repository's configured verification for any touched code/docs.
+3. Run `git diff --check`.
+
+## Open questions
+
+- Should this gap become implementation work, roadmap clarification, backlog cleanup, or a rejected false-positive record?
+- If implementation is needed, which existing active/backlog plan should own it?
diff --git a/tests/section-parser.test.ts b/tests/section-parser.test.ts
index 6df92beb..359a3b62 100644
--- a/tests/section-parser.test.ts
+++ b/tests/section-parser.test.ts
@@ -255,7 +255,8 @@ This sample must not count as the real section.
     // 174 release closeout: added evidence-battery package-sync plan to done.
     // 175 release prep: added ambient capture trust package-sync plan.
     // 176 release prep: added 0.35.0 package release-sync plan.
-    expect(hash(planIssueSnapshot)).toBe('d8d8777986758ddf5d505cfd732dcfbe62ef93b326358c375b3e551ac7bb5c9c');
+    // 178 portfolio follow-up: added active-open-questions-e9b7cdc8b3 backlog gap plan.
+    expect(hash(planIssueSnapshot)).toBe('3affef87e5b44e36c1c14a212ce5ba8078cfe86d88beaa8f81a67fbbec3f803b');
     expect(scaffold.failures).toEqual([]);
     // 168: evidence note 2026-06-12-168-dollar-verb-retirement.md added to .osc/releases.
     // 170 review hardening: evidence note refreshed with PR URL, final test count, and Codex-reported total_tokens.