[liugedragon]

Formatting a parsed Git binary diff currently drops its isBinary flag on the next parse. The formatted output contains only the diff --git line and any mode/rename headers, so consumers lose the indication that the file content needs separate handling.

Emit a Binary files ... differ summary for Git patches marked isBinary, using the existing filename quoting and /dev/null for creations/deletions. Document that this preserves the marker rather than binary file data.

Seven regressions cover modifications, creations, deletions, renames, copies, quoted filenames, and mixed text/binary multi-file patches. All seven fail before the fix and pass afterward. Actual git diff --no-index output for synthetic binary modification/creation/deletion cases also retains its flag after the round trip.

Validation on Windows / Node 22.18.0:

• yarn build: passed, including lint, CJS/ESM generation, type checks, and bundles (one existing TODO warning).
• yarn mocha 'test/patch/**/*.js': 194 passing.
• yarn test: 323 passing, with the same two async timing failures present on the unchanged baseline (316 passing): should not wait for a timer between iterations in async mode and does not starve timers while it runs. No test timeouts or async implementation were changed.
• Coverage: 99.20% lines, 96.82% branches, 100% functions.
• Independent Git 2.34.1 corpus: 40 real binary modification/creation/deletion/rename/copy diffs, each mixed with a text change, passed through CJS and ESM (80 round trips). Filenames include spaces, quotes, tabs, newlines, backslashes, and non-ASCII characters; all parsed metadata and text application results were preserved.
• git diff --check: passed.

Additional validation on Ubuntu 22.04 (WSL x86_64), Node 22.18.0 and Yarn 4.18.1: a clean source export with yarn install --immutable and the full yarn test command passed, including build, type checks, bundles, coverage and all 325 tests. The unchanged upstream base passed all 318 tests in the same environment.