feat: Add Ultra (32k token) thinking budget option

[YishenTu]

Adds a new xhigh/Ultra thinking budget tier with 32k tokens for extended thinking workflows.

This expands the thinking budget options from off/low/medium/high to off/low/medium/high/xhigh, providing users with maximum extended thinking capacity when needed.

The new option is automatically available in the UI via THINKING_BUDGETS without requiring additional component changes.

[claude]

PR Review: Add Ultra (32k token) thinking budget option

Summary

This PR adds a new xhigh thinking budget tier with 32k tokens, expanding the available options from off/low/medium/high to off/low/medium/high/xhigh. The changes are minimal, focused, and well-implemented.

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✅ Code Quality & Best Practices

Strengths:

• Minimal, focused changes: Only touches the necessary files (type definition and documentation)
• Consistent naming: Uses xhigh for the value and Ultra for the UI label, following the existing pattern
• No breaking changes: Purely additive - existing configurations remain valid
• Self-documenting: The THINKING_BUDGETS constant automatically populates UI components without requiring additional changes
• Documentation updated: CLAUDE.md correctly reflects the new option

Adherence to project patterns:

• Follows the established pattern in THINKING_BUDGETS array
• Type-safe with TypeScript union type extension
• Aligns with the project's modular architecture

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🐛 Potential Issues

None identified - The implementation is straightforward and correct.

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⚡ Performance Considerations

Minimal impact:

• No runtime performance impact - just adds a new option to a static array
• The 32k token budget itself will have cost/latency implications for users who select it, but this is expected behavior

Consideration:

• Users selecting xhigh should be aware of increased API costs and potential latency. Consider adding a warning or tooltip in the UI (future enhancement, not blocking for this PR).

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🔒 Security Concerns

None - This change doesn't introduce any security risks. It's a configuration option that affects token budget allocation, which is handled by the Claude Agent SDK.

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🧪 Test Coverage

Current state:

• The existing test suite in tests/unit/core/types/types.test.ts validates the ThinkingBudget type
• Tests at lines 93, 122, 150 use various budget values (off, medium, high)
• No tests specifically validate the xhigh option yet

Recommendation:
Consider adding test cases to validate the new xhigh option and verify the THINKING_BUDGETS array includes it correctly with 32000 tokens.

Note: These test additions are suggestions for improved coverage but not blockers for merging.

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📋 Additional Observations

Integration points verified:

• ✅ InputToolbar.ts iterates over THINKING_BUDGETS - new option will appear automatically
• ✅ ClaudianService.ts finds budget config via .find() - will handle new option correctly
• ✅ InstructionRefineService.ts and InlineEditService.ts use the same pattern - compatible
• ✅ Type system enforces valid values - TypeScript will catch any misuse

Documentation alignment:

• ✅ CLAUDE.md updated correctly in the Settings section (line 181)
• ✅ Token counts clearly documented: 0 | 4k | 8k | 16k | 32k tokens

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🎯 Verdict

✅ APPROVED - This is a clean, well-implemented feature addition that follows project conventions and requires no changes before merging.

Optional follow-ups (can be addressed in future PRs):

1. Add test coverage for the xhigh option
2. Consider adding UI tooltips explaining cost/latency implications of higher budgets
3. Update the "Models & Thinking" table in CLAUDE.md to mention the new Ultra option (currently only documents off/low/medium)

Great work! 🚀