[ANIRUDDHA ADAK (aniruddhaadak80)]

What does this PR do, and why?

generateUnifiedDiff hard-coded a one-line hunk header, "@@ -1 +1 @@", regardless of how many lines the hunk actually contains.

Linked issue

small fix, no issue

How did you verify it?

cd backend/cli && bun test test/patch/patch.test.ts -t "hunk line counts"

Regression proof: reverted ONLY the source fix while keeping both new tests: both failed with the exact header mismatch. Restored, 26/26 pass.

cd backend/cli && bun test test/patch/patch.test.ts -> 26 pass, 0 fail (was 24 before this change)

I read #779 (computeReplacements, the input side) and #826 (the parser) first: neither touches generateUnifiedDiff, so there is no overlap. Trailing-empty-line and hasChanges === false -> "" behaviour is preserved. The ,N form is emitted even when N is 1, which is valid unified diff and matches the form the ACP test fixture already uses.

Not verified: no git apply end-to-end run (no git binary path exercised). The generator's known simplification of dropping empty lines is untouched. The apply_patch suites show flaky 5000 ms timeouts both at base and with this change.

Two pre-existing conditions in this checkout, reproduced on the untouched base commit and therefore not caused by this change: �un run typecheck (turbo) fails with sgo: command not found, and �un run format:check reports roughly 30 files. I ran sc --noEmit for �ackend/cli and prettier on the files I touched instead; neither appears in the base warning list.

Checklist

• �un run check is green (format, typecheck, backend + frontend/ui + SDK tests)
• �un run --cwd frontend/workspace build succeeds if I touched rontend/workspace or rontend/ui (not applicable - no frontend/workspace or frontend/ui file changed)
• ./tooling/repo/generate.ts was run and the ooling/sdk output committed if I changed �ackend/cli/src/server (not applicable - no �ackend/cli/src/server file changed)
• [[x]] CHANGELOG.md has an Unreleased entry if the change is user-visible
• The matching docs page under rontend/docs/src/content/openscience/ is updated if behavior changed (not applicable - no documented behavior changed)
• Screenshots or a short video are attached for UI changes (not applicable - no UI change)
• No version bumps (package.json versions and tags are written by the release workflow)
• install and rontend/landing/public/install are still byte-identical if I touched either (not applicable - neither was touched)

I left the first box unticked rather than claiming it: �un run check cannot pass in this checkout because turbo cannot find sgo, and that failure reproduces on the base commit.

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[Aayam Bansal (aayambansal)]

Incorporated, reviewed, and validated in #953, now merged into main. Closing this original PR as superseded by the consolidated change.