fix(truncation): accurate overflow counts and omission indicators by FlorianBruniaux · Pull Request #833 · rtk-ai/rtk

FlorianBruniaux · 2026-03-25T21:48:57Z

Summary

fix(diff): condense_unified_diff reported +5 more when 190 lines were truncated — changes vec was capped at 15, so changes.len() - 10 maxed at 5. Fix: compute overflow as (added + removed) - 10 directly.
fix(git): compact_diff hunk truncation showed vague ... (truncated) with no count. Fix: track hunk_skipped separately, flush ... (N lines truncated) at each hunk/file boundary.
fix(git): filter_log_output silently dropped commit body lines beyond 3. A 20-line breaking-change description showed 3 lines with no indicator. Fix: append [+N lines omitted] when body is cut.

Adds 9 accuracy tests across 4 modules locking in correct overflow behavior.

Root cause pattern: cap a collection before computing the overflow count, then report capped_len - shown instead of true_total - shown.

Test plan

cargo test — 1122 passed, 0 regressions
cargo clippy --all-targets — 0 errors
Manual: rtk git diff on a large diff confirms count in truncation line
Manual: rtk git log on a commit with long body shows [+N lines omitted]

🤖 Generated with Claude Code

The overflow message "+N more" in condense_unified_diff was lying. The `changes` vec was capped at 15 entries, so `changes.len() - 10` could only reach 5 — reporting "+5 more" when 190 lines were actually truncated. Fix: track `added + removed` directly and compute true overflow as `(added + removed) - 10`. Adds 7 accuracy tests across 4 modules to lock in correct overflow reporting: - diff_cmd: overflow count matches true total (200 changes → "+190 more") - diff_cmd: no spurious overflow message for 8 changes - git: format_status overflow count is exact (25 staged → "+10 more") - git: compact_diff recovery hint present when hunk is truncated - grep: documents uncapped-vector invariant that prevents the diff bug - filter: smart_truncate kept + reported_more == total_lines Closes the test gap flagged in testing-patterns.md backlog for diff_cmd.rs. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Florian BRUNIAUX <florian@bruniaux.com>

Two silent truncation bugs in git.rs: 1. compact_diff: hunk truncation showed "... (truncated)" with no count. An LLM had no way to know if 5 or 450 lines were dropped. Replace with "... (N lines truncated)" by tracking hunk_skipped separately from hunk_shown — flush the count at each hunk/file boundary. 2. filter_log_output: commit body beyond 3 lines was silently dropped. A 20-line body explaining a breaking change would show 3 lines with no indicator that 17 were omitted. Now appends "[+N lines omitted]" when body_omitted > 0. Adds 2 RED-then-GREEN tests to lock in the new behavior. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Florian BRUNIAUX <florian@bruniaux.com>

Copilot

Pull request overview

This PR improves the accuracy and clarity of truncation/overflow reporting in RTK’s diff/log condensation paths, and adds tests to prevent regressions in overflow counts and omission indicators.

Changes:

Fix condense_unified_diff overflow reporting to use true total changes (added + removed) instead of a capped vector length.
Enhance git::compact_diff to report per-hunk/file truncation with explicit line counts, and enhance filter_log_output to indicate omitted commit body lines.
Add “truncation accuracy” unit tests across multiple modules to lock in correct overflow/omission behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
src/grep_cmd.rs	Adds a new truncation/overflow-focused unit test.
src/git.rs	Updates diff compaction truncation reporting and git log body omission signaling; adds related tests.
src/filter.rs	Adds a unit test asserting smart-truncate overflow accounting.
src/diff_cmd.rs	Fixes unified diff overflow computation and adds regression tests for accurate counts.

Copilot · 2026-03-25T21:52:38Z

+            } else if hunk_shown < max_hunk_lines && !line.starts_with("\\") {
                // Context line
-                if hunk_lines > 0 {
+                if hunk_shown > 0 {
                    result.push(format!("  {}", line));
-                    hunk_lines += 1;
+                    hunk_shown += 1;
                }
            }


compact_diff increments hunk_skipped only for added/removed lines beyond max_hunk_lines. Context lines (and any other non +/- lines in the hunk) that occur after the limit are currently ignored without incrementing hunk_skipped, so the reported "(N lines truncated)" can undercount the true number of lines dropped. Consider incrementing hunk_skipped for any additional hunk lines once hunk_shown >= max_hunk_lines (excluding the "\ No newline" marker if desired) so the count matches the actual truncation.

Copilot · 2026-03-25T21:52:38Z

+        let all_body_lines: Vec<&str> = lines
            .map(|l| l.trim())
            .filter(|l| {
                !l.is_empty()
                    && !l.starts_with("Signed-off-by:")
                    && !l.starts_with("Co-authored-by:")
            })
-            .take(3)
            .collect();
+        let body_omitted = all_body_lines.len().saturating_sub(3);
+        let body_lines = &all_body_lines[..all_body_lines.len().min(3)];



filter_log_output now collects all body lines into all_body_lines to compute body_omitted. For long commit messages this can allocate and retain a large Vec<&str> unnecessarily. You can keep the first 3 body lines while streaming through the iterator and count the remainder (or count total without storing) to compute the omission indicator with O(1) extra memory.

Copilot · 2026-03-25T21:52:39Z

+        // 25 staged files, default status_max_files = 15
+        // Should show 15, overflow = 25 - 15 = 10, report "+10 more"
+        let mut porcelain = String::from("## main...origin/main\n");
+        for i in 0..25 {
+            porcelain.push_str(&format!("M  staged_file_{}.rs\n", i));
+        }
+        let result = format_status_output(&porcelain);
+        assert!(
+            result.contains("+10 more"),
+            "Expected '+10 more' for 25 staged files (max_files=15), got:\n{}",


test_format_status_overflow_count_exact asserts +10 more based on an assumed default status_max_files = 15. Since format_status_output reads this limit from config::limits(), this test will start failing if the configured default changes. Consider deriving the expected overflow from config::limits().status_max_files (e.g., 25 - max_files) and asserting on that value instead of a hard-coded 10.

Suggested change

// 25 staged files, default status_max_files = 15

// Should show 15, overflow = 25 - 15 = 10, report "+10 more"

let mut porcelain = String::from("## main...origin/main\n");

for i in 0..25 {

porcelain.push_str(&format!("M staged_file_{}.rs\n", i));

}

let result = format_status_output(&porcelain);

assert!(

result.contains("+10 more"),

"Expected '+10 more' for 25 staged files (max_files=15), got:\n{}",

// 25 staged files, respect configured status_max_files from config::limits()

// Should show up to max_files, overflow = 25 - max_files, report "+<overflow> more"

let max_files = config::limits().status_max_files;

let total_files = 25;

let mut porcelain = String::from("## main...origin/main\n");

for i in 0..total_files {

porcelain.push_str(&format!("M staged_file_{}.rs\n", i));

}

let result = format_status_output(&porcelain);

let expected_overflow = total_files - max_files;

let expected_overflow_str = format!("+{} more", expected_overflow);

assert!(

result.contains(&expected_overflow_str),

"Expected '{}' for {} staged files (max_files={}), got:\n{}",

expected_overflow_str,

total_files,

max_files,

Copilot · 2026-03-25T21:52:39Z

+    #[test]
+    fn test_grep_overflow_uses_uncapped_total() {
+        // Confirm the grep overflow invariant: matches vec is never capped before overflow calc.
+        // If total_matches > per_file, overflow = total_matches - per_file (not capped).
+        // This documents that grep_cmd.rs avoids the diff_cmd bug (cap at N then compute N-10).
+        let per_file = config::limits().grep_max_per_file;
+        let total_matches = per_file + 42;
+        let overflow = total_matches - per_file;
+        assert_eq!(overflow, 42, "overflow must equal true suppressed count");
+        // Demonstrate why capping before subtraction is wrong:
+        let hypothetical_cap = per_file + 5;
+        let capped = total_matches.min(hypothetical_cap);
+        let wrong_overflow = capped - per_file;
+        assert_ne!(
+            wrong_overflow, overflow,
+            "capping before subtraction gives wrong overflow"
+        );
+    }


test_grep_overflow_uses_uncapped_total doesn't exercise any production code paths in grep_cmd—it only asserts arithmetic on local variables, so it would still pass even if the implementation started capping matches before computing overflow. Consider removing this test or replacing it with a test that validates the actual formatted output/overflow behavior (e.g., by extracting the per-file formatting/overflow calculation into a helper that can be unit-tested deterministically).

pszymkowiak

LGTM — all three truncation bugs fixed correctly, 9 tests added.

One minor note: compact_diff can emit two consecutive truncation messages when both per-hunk (100 lines) and global max_lines limits fire simultaneously. Rare in practice — can fix later.

Keep truncation accuracy fix (HEAD) — accurate overflow counts in condense_unified_diff. Drop test_condense_unified_no_truncation from develop (incompatible). Add test_no_truncation_large_diff and test_long_lines_not_truncated from develop (test compute_diff, no conflict). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

- Run cargo fmt on diff_cmd.rs and init.rs (line length violations) - Add Unreleased section to CHANGELOG.md with the two bug fixes from this PR (required by doc review CI gate) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com> Signed-off-by: Florian BRUNIAUX <florian@bruniaux.com>

FlorianBruniaux and others added 2 commits March 25, 2026 21:59

Copilot AI review requested due to automatic review settings March 25, 2026 21:48

Copilot started reviewing on behalf of FlorianBruniaux March 25, 2026 21:49 View session

Copilot AI reviewed Mar 25, 2026

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pszymkowiak approved these changes Mar 26, 2026

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pszymkowiak requested a review from aeppling March 26, 2026 08:00

FlorianBruniaux and others added 2 commits March 26, 2026 09:49

pszymkowiak merged commit 58a9633 into develop Mar 26, 2026
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pszymkowiak mentioned this pull request Mar 26, 2026

fix: truncation accuracy + Copilot init + binary file detection #859

Merged

4 tasks

This was referenced Mar 27, 2026

fix(grep): read stdin when piped instead of searching filesystem #881

Open

refactor(hooks,scripts): extract shared helpers to reduce duplication #882

Closed

maxkulish added a commit to maxkulish/rtk that referenced this pull request Apr 14, 2026

fix(sync): exact truncation counts in compact_diff (upstream rtk-ai#833)

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fix(truncation): accurate overflow counts and omission indicators#833

fix(truncation): accurate overflow counts and omission indicators#833
pszymkowiak merged 4 commits intodevelopfrom
fix/truncation-accuracy-tests

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FlorianBruniaux commented Mar 25, 2026

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