fix: add --no-ext-diff to git diff commands to support external diff tools#318
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tomasz-tomczyk merged 2 commits intotomasz-tomczyk:mainfrom Apr 20, 2026
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The --numstat call in DiffNumstatDir can also be affected by external diff tools. Add the flag for consistency with the other diff commands. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Problem
When a user has an external diff tool configured (e.g. difftastic, delta, or any tool set via
GIT_EXTERNAL_DIFFordiff.externalin gitconfig),git diffoutputs in the tool's custom format rather than standard unified diff. Crit'sParseUnifiedDiffcannot parse these formats, so it returns 0 hunks — causing the diff view to appear completely blank even though the file is correctly detected as modified.This is a silent failure: the file appears in the file list with a modified status icon, but clicking it shows no content. There is no error message to indicate why.
Example
With difftastic configured,
git diff AGENTS.mdoutputs:ParseUnifiedDiffexpects lines starting with+,-,@@hunk headers — none of which appear in this output. Result: 0 hunks, blank UI.Why detection still worked
The file list detection uses
git diff --name-status, which only outputs filenames and status letters (M,A,D). External diff drivers are not invoked for--name-statusoutput, so detection correctly identifies the file as modified. Only the content diff fetch is broken.Fix
Add
--no-ext-diffto allgit diffinvocations that produce diff content for parsing:fileDiffUnified— default diff (vs HEAD or merge base)fileDiffUnifiedCtx— same, with context cancellation for lazy loadingFileDiffScoped— branch/staged/unstaged scope diffsFileDiffForCommit— per-commit diffs in the commit selector sidebar--no-ext-difftells git to always use its built-in unified diff driver, regardless of any external diff configuration. This is the correct approach for programmatic diff consumption — external diff tools are designed for human-readable terminal output, not machine parsing.The
--name-statusdetection commands are unchanged since they are unaffected by external diff drivers.Testing
All 12 existing
TestFileDiff*tests pass. These tests run against real git repos and cover all modified code paths.Screenshots
Before
After
(Actual diff cutt off here, to hide sensitive info)
