rtk-ai/rtk

rtk git diff/show --max-lines may inflate savings same way as #1045

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#1561 opened on Apr 27, 2026

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bugeffort-smallfilter-qualitygood first issue

Description

Context

Follow-up flagged by @pszymkowiak in PR #1076 review.

#1045 was about rtk read counting user-requested line truncation as RTK token savings. The same pattern likely exists in:

  • src/cmds/git/git.rs:200 — git diff tracking
  • src/cmds/git/git.rs:314 — git show tracking

Both currently track against the compacted output. compact_diff itself is real RTK compression so that part is legitimate — but when a user passes --max-lines N to rtk git diff / rtk git show, the truncated portion gets counted as savings same as the original bug.

Reproduce (likely)

rtk git diff --max-lines 5  # large diff
rtk gain --history          # check if the saved-tokens row for this command is suspiciously high

Suggested fix

Apply the same pattern as #1076:

  1. Extract a pick_tracking_output(pre_truncation: Option<&str>, rtk_output: &str) -> &str helper (already lives in src/cmds/system/read.rs after #1076 merges — could be promoted to src/core/utils.rs).
  2. Capture the post-compact / pre-truncation content via std::mem::take when --max-lines is active.
  3. Pass the pre-truncation slice to timer.track() instead of the windowed output.

Out of scope here

  • Polluted historical data (separate concern — needs server-side cap or one-off migration, also flagged in #1076 review).

cc @pszymkowiak — opening as you suggested.

Contributor guide

Tech stack
rust
Domain
clideveloper experiencetooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Basic RustUnderstanding of rtk git commands
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue is a follow up to #1045 and builds on the fix in PR #1076. The main task is to apply the same `pick tracking output` helper pattern to `src/cmds/git/git.rs` at lines 200 and 314. First, ensure the helper from `src/cmds/system/read.rs` is promoted to `src/core/utils.rs` after #1076 merges. Then, capture the pre truncation content using `std::mem::take` when ` max lines` is active, and pass it to `timer.track()` instead of the windowed output. Testing should involve running `rtk git diff max lines 5` on a large diff and checking `rtk gain history` for inflated savings. No existing PRs or assignees are present, so the issue is open for contribution.