[ENHANCEMENT] Show Total and Net lines of code added/removed per task and/or iteration

[raf202]

Problem (one or two sentences)

Users cannot quickly tell, at a glance, how many lines the agent changed on a given iteration or across the whole task. This makes it harder to do a fast sanity check for "too creative" or "too little" changes before a deeper code review.

Context (who is affected and when)

Developers and reviewers using Roo Code to iterate on tasks. Most useful right after an iteration completes and when scanning a task history, especially for experienced devs who can judge expected scope by lines added/removed. Compact view on header for quick glance and expanded header details could be a good solution.

Desired behavior (conceptual, not technical)

When an agent iteration runs, show a simple summary of lines changed: a) a compact total with plus/minus (e.g., +120 / -30) visible in the compact task header for a quick glance, and b) a detailed view in the expanded task header that lists net lines and per-task/per-file breakdowns so reviewers can inspect where the edits happened. The compact view should give immediate signal; the expanded view should allow drill down.

Constraints / preferences (optional)

Keep the compact summary unobtrusive ans visible.
Display must be fast; computing the metric should not noticeably delay UI updates.
Exclude binary files and generated build artifacts by default.
Normalize whitespace and formatting-only changes to avoid noisy line counts.
Allow opt-out or toggles for teams that prefer not to surface line counts.

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Roo Code Task Links (optional)

No response

Acceptance criteria (optional)

No response

Proposed approach (optional)

Compute diffs between the file tree state before the iteration and after the iteration, counting lines added and removed per file. Do not rely on git history as the single source, because agent edits may not map neatly to commits and git-based counting can be brittle for the agent workflow. Use a controlled diff of the workspace snapshot to get accurate per-iteration numbers.

Aggregate per-file counts into: total added, total removed, and net. Expose UI: compact header shows total added/removed; expanded header shows net plus per-file breakdown and more detail.

Trade-offs / risks (optional)

No response

[roomote]

I've analyzed this issue and here's my proposed implementation plan:

Summary

The codebase already has the infrastructure for tracking line changes per file operation - diffStats: { added: number; removed: number } is computed in all file editing tools (ApplyPatchTool, EditFileTool, WriteToFileTool, SearchReplaceTool, ApplyDiffTool) and stored in tool messages. The UI also displays these stats per-file in the CodeAccordian component. What's missing is the aggregation at the task level and display in the TaskHeader.

Implementation Plan

1. Create a utility to aggregate diff stats from clineMessages

Create a new hook/utility in webview-ui/src/hooks/ that:

• Iterates through clineMessages array
• Parses tool messages (message.ask === 'tool' or message.say === 'tool')
• Extracts diffStats from each tool that has file editing operations (editedExistingFile, appliedDiff, newFileCreated)
• Aggregates totals: { totalAdded: number, totalRemoved: number, net: number }
• Optionally tracks per-file breakdown for expanded view

2. Update TaskHeader compact view

In the collapsed state of TaskHeader, add the aggregated line count summary next to the cost display:

• Format: +120 / -30 with green/red styling (matching the existing CodeAccordian styling)
• Only show if there were actual file changes (totalAdded > 0 || totalRemoved > 0)

3. Update TaskHeader expanded view

Add a new row in the expanded details table:

• Label: "Lines Changed" (or similar, will need localization)
• Value: Show +N / -N totals with green/red colors
• Optional: Add a collapsible per-file breakdown showing which files were modified

4. Add localization keys

Add the necessary translation keys for:

• chat:task.linesChanged - Label for the expanded view
• chat:task.linesAdded - Tooltip text
• chat:task.linesRemoved - Tooltip text

5. Handle edge cases

• Exclude binary files (the existing diff infrastructure already handles this)
• Handle cases where diffStats is null/undefined
• Ensure calculation is memoized to avoid re-computation on every render

Files to Modify

1. New file: webview-ui/src/hooks/useDiffStats.ts - Utility hook for aggregating stats
2. Modify: webview-ui/src/components/chat/TaskHeader.tsx - Add display in both compact and expanded views
3. Modify: locales/*/translation.json - Add localization keys

Questions/Considerations

1. Per-file breakdown: The issue mentions showing per-file breakdown in the expanded view. Should this be:

   • A simple list of files with their individual +/- counts?
   • A collapsible/expandable section?
   • Clicking on a file navigates to that file?

2. Settings toggle: The issue mentions "Allow opt-out or toggles for teams that prefer not to surface line counts." Should this be:

   • A global setting in the settings view?
   • A per-task toggle?
   • Deferred to a follow-up issue?

Please mention @roomote in a comment saying that you approve this plan (or provide feedback on the questions above), and I'll proceed with the implementation.

[hannesrudolph]

@roomote deleete your plan and make a new one from scratch. I am not saying your plan is bad.. but I am saying we updated some things in your prompting to potentially improve it.

[roomote]

I've seen your comment and will start fresh with a new plan. I'll explore the codebase, put together a new implementation plan, and open a PR to share progress.

[roomote]

Opened a draft PR with my attempt at addressing this: #11244

The implementation adds a useDiffStats hook that aggregates diffStats from all file-editing tool messages in clineMessages, then surfaces the totals in both the compact (collapsed) and expanded TaskHeader views. All tests pass (14 hook unit tests + 6 new TaskHeader integration tests). Feedback welcome!