feat(platform): add column headers to history diff viewer

[larryro]

Summary

• Add sticky "Current version" and "Snapshot version" column headers to the history diff dialog for better readability
• Add structuredResponsesEnabled flag and formatting cleanup to the web-assistant agent config
• Add translation keys for the new diff column headers

Test plan

• Open an agent's history and click "Compare changes" — verify sticky column headers appear above the diff
• Verify headers stay visible when scrolling through a long diff
• Confirm web-assistant agent still loads and functions correctly with updated config

Summary by CodeRabbit

• New Features

  • Added new agent configuration options for model preset selection and structured response control.
  • Added sticky header to agent history viewer displaying version labels for improved navigation during comparison.

• Localization

  • Added translation support for agent history comparison labels.

[greptile-apps]

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[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 58e25d4a-5f35-4958-859b-3f00cc7a5cf8

📥 Commits

Reviewing files that changed from the base of the PR and between 6881867 and 11892bf.

📒 Files selected for processing (3)

• examples/agents/web-assistant.json
• services/platform/app/features/agents/components/history-diff-dialog.tsx
• services/platform/messages/en.json

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📝 Walkthrough

Walkthrough

This pull request introduces UI enhancements for agent history comparison and updates agent configuration. Three files are modified: the web assistant agent configuration JSON adds two new fields (modelPreset: "fast" and structuredResponsesEnabled: false) with minor formatting adjustments; a TypeScript component adds a sticky two-column header row above a JSON diff viewer to display "current version" and "snapshot version" labels; and English translation strings are added for the new version labels in the i18n messages file.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the primary change: adding column headers to the history diff viewer, which is the main feature addition across the changed files.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/history-diff-headers-and-agent-config

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