fix(locale): prevent titlecase crash on missing session values

[Olusammytee]

Summary

• make Locale.titlecase safely handle undefined and
  ull values
• return an empty string for missing input instead of throwing at
  eplace
• prevent session loading/rendering crashes caused by legacy or incomplete message fields

Fixes Kilo-Org/kilocode#6319

[github-actions]

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[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (1 files)

• packages/opencode/src/util/locale.ts - Adds null/undefined safety to titlecase() with a falsy guard clause. Clean and correct defensive change.

[Copilot]

Pull request overview

This PR fixes a crash in the Kilo CLI when loading sessions with messages by making the Locale.titlecase function safely handle null and undefined values. The issue occurred when attempting to sync sessions between VS Code KiloCode and Kilo CLI, where legacy or incomplete message fields could cause the function to crash with a "str3.replace is not an object" error.

Changes:

• Modified the titlecase function signature to accept optional and nullable string parameters (string | null | undefined)
• Added a guard clause to return an empty string for falsy input values, preventing the crash when .replace() is called on null/undefined

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[Copilot]

The new null/undefined handling behavior for the titlecase function is not covered by tests. Consider adding test cases to verify the function correctly returns an empty string when passed undefined, null, or empty string values. This would prevent regression and document the intended behavior.