[danielss-dev]

Summary

First slice of DAN-92: Amend staged changes into this commit on a graph commit, as one operation.

• Creates a fixup! commit, then replays an explicit oid plan (pick each commit in the range, fixup the new oid immediately after the target). Does not use --autosquash, so two commits that share a subject stay distinct.
• Autostashes unstaged work for this path only.
• Confirmation lists every commit the rewrite will replay, marks the target, refuses when the range contains a merge commit, and warns when the target is already on @{upstream} (a force push will be needed).
• Abort of a conflicted rewrite soft-resets back to the pre-fixup tip (.git/strand-amend-into). Continue uses the existing sequencer.
• Entry points: graph context menu, commit-detail more menu, command palette (amend-into). Hunk and line moves are out of this slice and were not filed.

Proof

cargo test -p strand-core --lib history::tests::amend_into -- --nocapture — 7 passed, 0 failed.

• Fold C1..C3. Staged edit to a.txt (touched in C1) plus an unstaged edit to c.txt. After the action, subjects stay c1, c2, c3; C1's blob is a\nplus; C2/C3 blobs are unchanged; the worktree still has c\nlocal; the index for c.txt is still c; no fixup! remains. Rewritten oids: 414d34e9…, b88d1ad5…, 901dd48d….
• Oid plan, duplicate subjects. Two commits both subject same. The chosen oid's diff contains +plus; the later same-subject commit's diff for that file is empty.
• Root target. --root rebase; file becomes a\nplus; subjects stay root, c2.
• Conflict → Abort. Rebase pauses with the marker present. Abort restores the original tip (fee6453d…), puts staged back in the index, keeps unstaged g\nlocal, and leaves no fixup! commit.
• Conflict → Continue. Resolving the pauses finishes the rewrite. C1's blob is staged; subjects stay c1, c2, c3; unstaged g.txt is preserved; the marker is gone.
• Merge in range. Plan lists feature, main, Merge branch 'feature', after and sets has_merge. The operation errors with this range contains a merge commit — Strand won't rewrite it. HEAD and the staged diff are unchanged.
• Already on upstream. C1 reachable from @{upstream} → pushed=true. A newer local-only commit → pushed=false. HEAD and origin/main stay put.

Local gates before push: cargo test for the CI packages, cargo clippy -p strand-core -p strand-tauri -p strand-ops -p strand-headless -p strand-azdo-protocol -p strand-azdo -- -D warnings, pnpm --filter ./ui test (105 files, 626 tests), and pnpm --filter ./ui exec tsc --noEmit all exited 0.

CI

Native agent review (Windows) failed twice in pull_requests::pages::tests::cancellation_terminates_an_active_read before the WebView2 step: PowerShell did not create the ready file within 10s (child did not reach its cancellation checkpoint). That startup budget is now 30s. The cancel-latency check is still under 5s.

Test plan

• CI, including Native agent review (Windows)
• Graph commit with staged changes → confirm dialog lists the rewrite range → history folds the change into that commit
• Unstaged edits survive; abort of a conflict restores the original tip
• Merge in the range is refused; a pushed target shows the force-push warning

Review fixes

• Abort only undoes amend-into when the abort was the amend's own rebase and HEAD is still the fixup commit. The marker now records the original and fixup IDs. A stale marker is dropped on any other abort.
• Continue checks for an autostash that failed to re-apply (git ls-files --unmerged), names the stash, and returns an error instead of a silent success. The direct path does the same.
• New tests:
  • a merge commit as the target is refused without rewriting;
  • a stale marker doesn't reset an unrelated abort;
  • Continue surfaces a conflicting autostash.
• Reverted ee9e881, the 30s Windows startup wait (febb96b). The empty ci: commits stay, because removing them would need a force push.

Merge order 157 → 153 → 155 → 154 → 156 → 158: this PR must adapt to #155 (new rebase / interactive_rebase signatures, and passing update_refs). #156 must wrap amend_into in its journal.