refactor: extract shared patch helpers

[benvinegar]

Summary

• Extract patch normalization, Git-format patch handling, git-log stripping, chunking, and DiffFile construction into focused shared helpers.
• Reuse the shared helpers from the app loader, pager detection, Git VCS placeholders, and public OpenTUI model API.
• Keep Git untracked-file patch header rewriting at the Git loader boundary and add OpenTUI coverage for noprefix patch normalization.

Verification

• bun run typecheck
• bun run format:check
• bun run lint
• bun test src/core/patch/gitLog.test.ts src/core/loaders.test.ts src/opentui/HunkDiffView.test.tsx src/core/pager.test.ts src/core/vcs/git.test.ts
• bun test (543 pass, 9 skipped)

This PR description was generated by Pi using OpenAI GPT-5.1

[greptile-apps]

Greptile Summary

This PR extracts five focused helper modules (diffFile.ts, patch/chunks.ts, patch/gitFormat.ts, patch/gitLog.ts, patch/normalize.ts) from the monolithic loaders.ts, and rewires the app loader, pager, Git VCS adapter, and public OpenTUI API to share them. As a side-effect, createHunkDiffFilesFromPatch now runs the full normalization pipeline (CRLF, terminal control, git-log stripping, noprefix rewriting) before parsing — a genuine behavioral improvement covered by a new test.

• ~490 lines are removed from loaders.ts by delegating to the new shared helpers; no logic was changed during the move.
• createSkippedLargeMetadata in vcs/git.ts now accepts an explicit type parameter, and countHunkDiffStats in model.ts is re-exported as an alias to the shared countDiffStats.
• A new HunkDiffView test confirms that noprefix diff --git headers are correctly normalized through the public createHunkDiffFilesFromPatch API.

Confidence Score: 5/5

Safe to merge — pure refactoring with identical logic in all moved functions, full test suite passing, and one net-new test for the noprefix normalization improvement.

Every extracted function is a byte-for-byte move of existing logic. The only intentional behavioral change — running normalizePatchText in createHunkDiffFilesFromPatch — is additive and directly covered by the new OpenTUI test. The findPatchChunk used by model.ts now uses slightly more robust matching from chunks.ts, which is strictly a superset of the old direct-path matching.

No files require special attention; the most structurally significant changes are src/core/loaders.ts (large deletion) and src/opentui/model.ts (behavioral improvement), both of which look correct.

Important Files Changed

Filename	Overview
src/core/diffFile.ts	New shared helper file exporting countDiffStats, buildDiffFile, and createSkippedLargeMetadata; clean extraction from loaders.ts with identical logic
src/core/patch/normalize.ts	New thin orchestration module combining stripTerminalControl, stripGitLogMetadata, and normalizeGitPatchPrefixes into normalizePatchText; correct pipeline order matches original loaders.ts implementation
src/core/patch/gitFormat.ts	Wholesale move of normalizeGitPatchPrefixes and all supporting helpers from loaders.ts; logic is identical, function is now exported for broader reuse
src/core/patch/chunks.ts	splitPatchIntoFileChunks and findPatchChunk moved from loaders.ts; the shared findPatchChunk uses stripPrefixes + a/b prefix search which is slightly more robust than the old model.ts version it replaces
src/core/git.ts	normalizeUntrackedPatchHeaders and escapeUntrackedPatchPath moved from loaders.ts and made exported; behavior is identical to the original private functions
src/core/loaders.ts	~490 lines removed by delegating to new shared helpers; normalizePatchChangeset now calls normalizePatchText instead of the inline chain
src/core/vcs/git.ts	Removes its own createSkippedLargeMetadata and uses the shared version from diffFile.ts; call site correctly passes 'change' as the explicit type argument
src/opentui/model.ts	createHunkDiffFilesFromPatch now applies normalizePatchText before chunking/parsing, giving the public API noprefix and CRLF handling; countHunkDiffStats re-exported as alias to countDiffStats

_{Reviews (1): Last reviewed commit: "refactor: extract shared patch helpers" | Re-trigger Greptile}