[ENHANCEMENT] Add a final "view diff" upon finishing a task

[Yasand123]

Problem (one or two sentences)

I think it's good QoL change to have a final "view diff" when the task finishes that shows the diff of the final result vs the initial state.

Context (who is affected and when)

After the task is finished you want to check what changed in an easy way.

Desired behavior (conceptual, not technical)

Add a "view diff" button when a task is finished. It will compare the final code vs the initial code.

Constraints / preferences (optional)

No response

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)

No response

Trade-offs / risks (optional)

No response

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

Summary

Add a "View Diff" button to the task actions that shows all file changes made since the task started. This leverages the existing checkpoint system which already supports a "full" diff mode.

Implementation Plan

1. Modify webview-ui/src/components/chat/TaskActions.tsx

Add a "View Diff" button that:

• Is only visible when checkpoints are enabled AND at least one checkpoint exists
• Uses the existing checkpointDiff message with mode: "full" to show changes from the first checkpoint to the current state
• Gets the first checkpoint hash from clineMessages (filtering for say === "checkpoint_saved" messages)

2. Add translation strings

Add i18n keys for the new button label and tooltip in the translation files.

3. Changes required

Files to modify:

• webview-ui/src/components/chat/TaskActions.tsx - Add the "View Diff" button
• webview-ui/src/i18n/locales/en/chat.json (and other locales) - Add translation string

No backend changes needed - The checkpoint diff functionality already exists and the "full" mode is already implemented in src/core/checkpoints/index.ts.

Technical Details

The button will:

1. Access clineMessages and enableCheckpoints from useExtensionState()
2. Find the first checkpoint hash: clineMessages.find(m => m.say === "checkpoint_saved")?.text
3. On click, send: vscode.postMessage({ type: "checkpointDiff", payload: { commitHash: firstCheckpointHash, mode: "full" } })
4. This triggers the existing checkpointDiff handler which uses VS Code's native diff viewer

Benefits

• Minimal code changes by reusing existing infrastructure
• Consistent with existing checkpoint diff UI patterns
• Works for any task that has checkpoints enabled
• Available both during and after task completion

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.

[virtushda]

@roomote I approve!

I've seen the approval and will proceed with implementing the "View Diff" button for finished tasks. I'll open a draft PR to share progress shortly.

Opened a draft PR with my attempt at addressing this: #12149

The PR adds a "View Diff" button to the task actions toolbar that shows all file changes since the task started, reusing the existing checkpoint diff infrastructure. Feedback welcome!