docs: correct plan 20A issue scope

docs/execution/approved-issue-plans-ledger.md

@@ -52,7 +52,7 @@ state changes are outside scope.
 | 17 list/skill pagination | #2751, #3040 | blocked corrective work; diagnostic-ready | audit `task_1c6582ccdeae` | `codex-audit-rendering-12-19` | `7a98f6662` → no source change | renderer owner shared with 13/14/18 | merged ordered-marker/wrap/level-gap fixes present; current residual not reproduced | audit focused PDF suites, typecheck, boundaries, build passed | — | retain controls; add fix only from exact failing list/skill fixture | #2751 source absent; #3040 current fixture no longer proves residual clipping |
 | 18 preview/export geometry | #2683 | blocked corrective work; diagnostic-ready | audit `task_1c6582ccdeae` | `codex-audit-rendering-12-19` | `7a98f6662` → no source change | share output-boundary harness with 12; viewer owner exclusion | current viewport/page-size/margin baselines pass; video alone cannot locate cause | audit page/preview tests, affected typechecks, boundaries, build passed | — | compare identical preview/download bytes, MediaBoxes, ink bounds, viewport, DPR | exact JSON/PDF/browser/DPR/zoom/page settings absent |
 | 19 literal rich-text whitespace | #3397 | pending after 16 | unassigned | planned `codex/issue-3397-literal-whitespace` | `7a98f6662` → — | stack/rebase after 16; coordinate DOCX/PDF/editor with 31 | verified current marked-policy gap; approved marker contract and four-space tabs remain implementation-ready | audit whitespace/indentation suites, affected typechecks, boundaries, build passed | — | implement web/PDF/DOCX atomically after table seam stabilizes | no product blocker; serialized file ownership only |
-| 20 section restoration | #3378, #3265, #2921 | 20A implementing; residuals split | `task_4237c974827a` / `ctx_00770ded7b0d` | `codex/issue-3378-hidden-section-recovery` | `7a98f6662` → work active | 20A before 21/31; placement semantics before 29 | 20A hidden recovery ready and executing; 20B defensive unplaced recovery waits for helper contract; reporter causes remain unproved | audit focused web/resume tests, affected typechecks, boundaries passed; implementation tests running | — | complete and independently review 20A; then separately assess 20B | #3378/#3265 need version/action/sanitized JSON; defensive fix cannot close them |
+| 20 section restoration | #3378, #3265, #2921 | 20A implementing for #2921; residuals split | `task_4237c974827a` / `ctx_00770ded7b0d` | `codex/issue-2921-hidden-section-recovery` | `7a98f6662` → work active | 20A before 21/31; placement semantics before 29 | compact hidden-section recovery for verified #2921 executing; 20B defensive unplaced recovery waits for helper contract; #3378/#3265 causes remain unproved | audit focused web/resume tests, affected typechecks, boundaries passed; implementation tests running | — | complete and independently review #2921-only 20A; then separately assess 20B | #3378/#3265 need version/action/sanitized JSON; defensive fix cannot close them |
 | 21 section heading visibility | #3060 | pending after 20A | audit `task_47ed7eb02d48` | `codex-audit-builder-20-34` | `7a98f6662` → no source change | 20A → 21 → 31 | runtime PDF seam exists; persisted schema/menu/DOCX/accessibility contract absent; Q1–Q3 make unit ready | audit schema/web/PDF/DOCX/resume suites and typechecks/boundaries passed | — | add migration-safe flag, menu, PDF/DOCX visual behavior, retained semantic label | serialize shared section/schema files |
 | 22 skill keyword presentation | #2785 | pending implementation | audit `task_47ed7eb02d48` | `codex-audit-builder-20-34` | `7a98f6662` → no source change | must precede/serialize 34 | array currently comma-joined; inline/list contract ready for built-in and custom Skills | audit schema/web/PDF/DOCX suites and typechecks/boundaries passed | — | select explicit Skills-specific schema trait; implement inline compatibility and semantic list mode | exact schema owner chosen during implementation; no product gate |
 | 23 pagination controls | #3350, #3090 | pending 23A/23B; 23C blocked | audit `task_47ed7eb02d48` | `codex-audit-builder-20-34` | `7a98f6662` → no source change | 23B → possible 23C | 23A authored-vs-physical page guidance ready; renderer clips oversized `wrap=false` section; item policy unproved | audit focused PDF/web suites and typechecks/boundaries passed | — | publish 23A; build short/boundary/oversized matrix in 23B before item control | safe oversized-item fallback and widow/orphan UI remain unresolved |
@@ -120,7 +120,7 @@ state changes are outside scope.
 | Plan 16 implementation | `task_f3d05a6ebb86` / `ctx_686ba93fc8af` | `codex/issue-3196-editable-tables` | complete; worker released | commit `83aca184e`; atomic editable supported tables, lossless unsupported fallback, PDF border geometry, persistence/E2E |
 | Plan 16 independent review | `task_e52d01cff964` / `ctx_63c00e7abb56` | same Plan 16 worktree | complete; changes required; worker released | P1 unsupported descendant markup can normalize destructively; P2 conversion is still HTML and E2E does not prove unrelated save persistence; orchestration report accepted by brief |
 | Plan 16 review fix | `task_7b7368639ff8` / `ctx_ba9ed045764f` | same Plan 16 worktree | implementing | fail-closed unsupported grammar, removal of out-of-scope conversion UX, and persisted unrelated-edit E2E proof via TDD |
-| Plan 20A implementation | `task_4237c974827a` / `ctx_00770ded7b0d` | `codex/issue-3378-hidden-section-recovery` | implementing | hidden-section recovery unit from current `origin/main`; test, commit, and report without publication |
+| Plan 20A implementation | `task_4237c974827a` / `ctx_00770ded7b0d` | `codex/issue-2921-hidden-section-recovery` in worktree `issue-3378-hidden-section-recovery` | implementing | #2921-only hidden-section recovery unit from current `origin/main`; test, commit, and report without publication |
 | Plan 10 implementation | `task_fd191afc86ba` / `ctx_5100e7419c11` | `codex/issue-2836-retired-link-notices` | implementing | prospective 90-day owner-only retired-link attempt notices with migration, privacy limits, and E2E |
 
 ## Existing PR and residual accounting