docs(plan): paused 2026-10-31; the two checkpointed worktrees and how to resume

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

plan/HANDOFF.md

@@ -18,7 +18,7 @@ You are the engineering manager (EM) of a team implementing the remaining work o
 
 - `main` is `bfd453b6`. Landed since the hand-off: U0a, U0b, U0c, P7, P9a, P13 steps 1-3, P4b S4.1, S4.2, S4.3 (2026-10-26 to 2026-10-27), then S4.4, S5, S6, S7 and P6 (2026-10-29, merged from the paused branches by the planning session). Live on the owner's books: P0 to P3, Projects, P4b S1 (`document_standing`); everything behind `documents_v2` waits for the owner's upgrade (Q-5).
 - Nothing is built and unmerged. Branch `ci-fixes` (`76285434`, a fuzz target's renamed path and a regression test) is the one branch left to merge.
-- Landed 2026-10-29 by this session's subagents in three waves: U0d, U0e, S4.5, P4, P5, P8, P10 (the runbook), P11a steps 0-4 plus the unsigned macOS bundle job, P11b, P13 steps 4-6 (the spec lives at `git.swaits.com/swaits/bookspec`). Building: P11c (branch `P11c`, proven by the portable CI jobs). Left: P11a steps 5-7 (signing deferred, D-64), P12, the owner's re-audit.
+- Landed 2026-10-29 to 2026-10-31 by this session's subagents in four waves: U0d, U0e, S4.5, P4, P5, P8, P10 (the runbook), P11a steps 0-4 plus the unsigned macOS bundle job, P11b, P11c (the Windows port; `main` gates on Linux, macOS and Windows), P13 steps 4-6 (the spec lives at `git.swaits.com/swaits/bookspec`). **Paused 2026-10-31** with two checkpointed worktrees, `../wb-P12` (P12 step 1) and `../wb-P11a` (the in-app update accept, the Windows installer job, translocation): see `plan/STATUS.md` "Paused" for what each holds and how to resume. Left after them: P12 step 2 (the run), P11a steps 5 and 7 (signing deferred, D-64), the owner's re-audit and trials.
 - The plan's section 8 was rewritten on 2026-10-26 for this hand-off and revised on 2026-10-28 (section 0, "What changed on 2026-10-28"; `plan/2026-10-28_DRIFT_REPORT.md`). Sections 1 to 7 are the older design and carry strike-throughs (`~~text~~ → D-n`) and "As built" notes where the build or a decision departed; where section 8 and an earlier section disagree, section 8 is right.
 - Mutation testing is paused until unit P12 (decision D-33). Workers never run `cargo mutants`; each unit writes a "For P12" paragraph in `docs/testing.md` instead (recipe R-G).
 - The owner's live books are never touched by anyone on this team. The only books a worker uses are test fixtures and throwaway books made by `wanderbooks setup` in a scratch root. A unit's new writes are refused on the owner's books until the owner's format upgrade; merging never waits for that.