fix(restack): track parent_revision to prevent false conflicts after squash-merge

[dubscode]

Summary

• Adds parent_revision field to Branch state tracking the parent's tip SHA at fork/rebase time
• Restack uses stored SHA as oldBase instead of getMergeBase(), which resolves to wrong ancestors after squash-merge reparenting
• Updates parent_revision across create, restack, sync, submit, and post-merge flows
• Falls back to getMergeBase() when parent_revision is absent (backward compat for existing stacks)
• Adds CI test coverage reporting with artifact upload

Test plan

• E2E test: squash-merge-then-restack produces zero false conflicts
• Backward compat: restack works when parent_revision absent
• Normal restack updates parent_revision after rebasing
• parent_revision preserved during post-merge reparenting
• All 338 tests pass, typecheck clean, lint clean

[Copilot]

Pull request overview

Adds parent_revision tracking to DubStack branch state so restack can use a stable “old base” SHA (instead of git merge-base) and avoid false conflicts/duplicate commits after squash-merge + reparent workflows. Also introduces Vitest coverage reporting in CI and adds bd (beads) repo integration files.

Changes:

• Add optional parent_revision field to persisted branch state and propagate it through create/restack/sync/submit flows.
• Update restack to prefer parent_revision for parentOldTip, with fallback to getMergeBase() for backward compatibility; add tests for squash-merge scenarios and state roundtrips.
• Add Vitest coverage configuration + CI artifact upload; add bd (beads) configuration/hooks and related ignores/docs.

Reviewed changes

Copilot reviewed 26 out of 30 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
vitest.config.ts	Enables V8 coverage reporting and configures include/exclude/reporters.
src/lib/state.ts	Adds parent_revision to Branch and allows addBranchToStack to store it.
src/lib/state.test.ts	Adds roundtrip + addBranchToStack tests for parent_revision.
src/commands/sync.ts	Updates sync bookkeeping to write parent_revision during markBranchSynced.
src/commands/sync.test.ts	Adds tests covering preservation/update behavior for parent_revision during sync flows.
src/commands/submit.ts	Sets parent_revision when recording submit baseline metadata.
src/commands/submit.test.ts	Adds test asserting submit sets parent_revision to base SHA.
src/commands/restack.ts	Uses parent_revision as parentOldTip and updates it after rebases / continue.
src/commands/restack.test.ts	Adds coverage for parent_revision behavior and squash-merge-then-restack regression tests.
src/commands/post-merge.test.ts	Adds test asserting reparenting preserves parent_revision.
src/commands/create.ts	Captures parent tip SHA and stores it as parent_revision on branch creation.
src/commands/create.test.ts	Adds test asserting create sets parent_revision to parent tip.
pnpm-lock.yaml	Adds lockfile entries for Vitest coverage provider and transitive deps.
package.json	Adds test:coverage script and @vitest/coverage-v8 dev dependency.
CLAUDE.md	Adds Claude-specific pointer file.
AGENTS.md	Adds bd (beads) issue tracking + “landing the plane” workflow documentation.
.gitignore	Ignores coverage output and Dolt/DB artifacts.
.github/workflows/ci.yml	Runs pnpm test:coverage and uploads coverage/ artifact.
.claude/settings.json	Configures Claude hooks to run bd prime.
.beads/metadata.json	Adds beads metadata for Dolt-backed tracking.
.beads/interactions.jsonl	Adds beads interactions log file.
.beads/hooks/prepare-commit-msg	Adds beads-managed git hook wrapper.
.beads/hooks/pre-push	Adds beads-managed git hook wrapper.
.beads/hooks/pre-commit	Adds beads-managed git hook wrapper.
.beads/hooks/post-merge	Adds beads-managed git hook wrapper.
.beads/hooks/post-checkout	Adds beads-managed git hook wrapper.
.beads/dolt-monitor.pid.lock	Adds beads runtime lock file.
.beads/config.yaml	Adds beads configuration template.
.beads/README.md	Adds beads usage documentation for the repo.
.beads/.gitignore	Ignores beads/Dolt runtime and local-only artifacts within .beads/.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

Comments suppressed due to low confidence (1)

src/commands/restack.ts:175

• executeRestackSteps mutates state (via updateParentRevision) as branches are successfully rebased, but if a later step conflicts you return without persisting those updates. On --continue, the earlier steps are already marked done so their parent_revision updates will never be written, leaving state stale. Consider writing state after each successful rebase, or at least persisting state before returning { status: 'conflict', ... }.

      await rebaseOnto(parentNewTip, step.parentOldTip, step.branch, cwd);
      step.status = 'done';
      rebased.push(step.branch);
      updateParentRevision(state, step.branch, parentNewTip);
      await writeProgress(progress, cwd);
    } catch (error) {
      if (error instanceof DubError && error.message.includes('Conflict')) {
        step.status = 'conflicted';
        await writeProgress(progress, cwd);
        return { status: 'conflict', rebased, conflictBranch: step.branch };
      }

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