What causes "Incomplete PR diff: a file patch is missing" in Hmbown/CodeWhale?

Re-run with plain git diff options: `git diff --no-ext-diff --no-color base...head` and confirm every `diff --git` header has a following `index`/hunk body

Hmbown/CodeWhale · error

Incomplete PR diff: a file patch is missing

Error message

Incomplete PR diff: a file patch is missing

What it means

While scanning the diff, complete_file_set requires every `diff --git <a> <b>` file header to be followed by an actual patch body (a valid @@ hunk or binary metadata). When a new file header appears while the previous file (files > 0) never produced has_patch, the previous file's patch is missing entirely and the review aborts.

Solutions

Re-run with plain git diff options: `git diff --no-ext-diff --no-color base...head` and confirm every `diff --git` header has a following `index`/hunk body
Check that the file count in the error matches view.changed_files; if fewer, the fetch truncated and the diff must be re-fetched completely
Disable external diff/renames filters for the review path (the tool already passes --no-ext-diff; ensure no repo config overrides it via diff.external)

Example fix

// before: repo config with an external diff driver
git config diff.external /usr/bin/custom-diff
// after: unset it so --no-ext-diff has nothing to override
git config --unset diff.external

Defensive patterns

Strategy: validation

Validate before calling

// every 'diff --git' header must be followed by an 'index' line
let lines: Vec<&str> = diff.lines().collect();
for (i, l) in lines.iter().enumerate() {
    if l.starts_with("diff --git ") {
        assert!(lines.get(i + 1).map_or(false, |n| n.starts_with("index ")), "file patch missing after header at line {}");
    }
}

Try / catch

match diff_with(&view) {
    Err(e) if e.to_string().contains("file patch is missing") => eprintln!("refetch complete diff; check output limits and external diff drivers"),
    other => other?,
}

Prevention

Unset diff.external / diff.<driver>.command in the review checkout
Raise any output truncation limits used by the wrapping process
Verify fetched diff contains exactly view.changed_files 'diff --git' headers

When it happens

Trigger: A `diff --git` header is present but its body was dropped — e.g. truncation removed everything after the header, or `git diff` was run with flags limiting per-file output for a file that changed.

Common situations: Very large diffs clipped by output limits; renames/mode-only changes filtered out by diff options; external diff drivers suppressing output for specific file types; corrupted tool output pipelines.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/7157ff795ac91ddd. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/tools/review_pr.rs:197

                    remaining.1 -= 1;
                    additions += 1;
                }
                Some(b'-') if remaining.0 > 0 => {
                    remaining.0 -= 1;
                    deletions += 1;
                }
                Some(b' ') if remaining.0 > 0 && remaining.1 > 0 => {
                    remaining.0 -= 1;
                    remaining.1 -= 1;
                }
                Some(b'\\') => {}
                _ => bail!("Incomplete PR diff: a text hunk is truncated or malformed"),
            }
            continue;
        }
        if line.starts_with("diff --git ") {
            if files > 0 && !has_patch {
                bail!("Incomplete PR diff: a file patch is missing");
            }
            files += 1;
            has_patch = false;
            has_full_index = false;
        } else if line.starts_with("index ") {
            has_full_index = full_index_objects(line);
        } else if let Some((_, old, new)) = super::review_hunks::parse_hunk_header(line) {
            remaining = (old, new);
            has_patch = true;
        } else if line.starts_with("@@") {
            bail!("Incomplete PR diff: malformed hunk header");
        } else if [
            "new file mode ",
            "deleted file mode ",
            "old mode ",
            "new mode ",
            "rename from ",
            "rename to ",

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