Replay source stacks from deterministic plans

[nishu-builder]

std/git-rebase-i reads rebase/plan inside a selected feature directory. pick applies one commit or a range’s net change, message supplies a message file, and branch saves a layer with an automatically assigned number.

Every invocation runs from the beginning using the plan’s fixed committer. On conflict it leaves rebase/work and Git’s report; edit the draft, replace the failed pick with the resolved range, and rerun. Completion replaces the numbered entries, preserves other files, and removes rebase/.

The same plan can combine tool-call history into a layer, so there is no separate layer-creation tool or special working-layer name.

[nishu-builder]

Parsimony review. Most of this PR's size comes from pause/resume: done/here records, tamper checks, and the conversation-history checkpoint walk. Because every step is a pure function of object ids, re-running the plan from onto on each call with a fixed committer gives the same result without any of that. The plan language can also drop drop and squash. Details inline and in the #278 review.

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Generated by Claude Code

[nishu-builder]

Closing as superseded: stacks went a different way on main. #293 (design/stacks.md), #291 (create-squashed-stack), and #296 (merge with an optional merge-base) cover building and restacking layers without a replay plan. The branch stays in place if any of this is needed later.

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Generated by Claude Code