[Bug]: PNG files in PR Code tab expand to blank content #33909

Before submitting

• I searched existing issues and did not find an exact duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/web / apps/desktop — pull request Code tab

Steps to reproduce

1. Open a GitHub PR containing newly added PNG images alongside text changes.
2. Open its Code tab in T3 Code.
3. Expand an image file row.

Observed with a four-file PR containing two added PNGs and two modified text files. Both PNG rows show the expanded chevron, but no image or explanatory message appears. The expand animation plays.

Expected behaviour

Expanding an image change should show a preview, or at least an explicit unsupported/binary-file message with a way to view the image. It should not silently present an empty expanded file.

Actual behaviour

Image file headers expand to blank content. The animation runs, but waiting does not reveal an image. Text file changes have normal line counts.

Screenshot

Both PNG rows are expanded, but no image content is shown. Personal details have been blurred.

Impact

Minor bug or occasional failure: image changes cannot be inspected from the PR Code tab, and the blank state gives no explanation.

Environment

Observed in T3 Code (Beta) desktop version 0.18 on macOS (version confirmed by the reporter). Source investigation used checkout fa2f4ff; this does not establish the installed desktop build's SHA.

Investigation

The affected PR's GitHub files API returned both PNGs as added files with zero additions/deletions and no patch. The whole-diff endpoint returned ordinary binary entries, for example:

diff --git a/figures/example.png b/figures/example.png
new file mode 100644
index 0000000..e7f9ad7
Binary files /dev/null and b/figures/example.png differ

Replaying this shape through the installed @pierre/diffs/utils/parsePatchFiles produces a file entry with type: "new", hunks: [], zero split/unified line counts, and empty addition/deletion arrays.

PullRequestCodeTab.tsx feeds parsed files into StyledDiffCodeView; no image-rendering branch was found on this path. apps/web/src/lib/diffFileContents.ts supplies text contents for diff context expansion, and the GitHub adapter's file-content reader rejects binary content. This explains the header-only result at the data/parser boundary. The Mac UI was not independently reproduced during this investigation; the visible symptom and animation were reported by the user.

Related reports

• [Bug]: PR Code tab shows empty file diffs when GitHub omits patches on large API pages #31404 has a similar empty-expansion symptom, but concerns missing text patches on large GitHub API pages. This reproduction is a small PR with genuine binary PNG entries.
• feat(diffs): preview locally cached Git LFS images #27145 proposed previews for locally cached Git LFS images and was closed without merging; these PNGs are ordinary binary entries.

Workaround

View the changed images on GitHub.

Report prepared with GPT-6.1 Sol through the Codex harness.