🤖 feat: make compact model preference sticky globally

[ammar-agent]

Overview

Makes the /compact -m <model> preference sticky globally. When users specify a compaction model, it becomes their default for all future compactions across all workspaces and sessions.

Changes

• Storage: Added PREFERRED_COMPACTION_MODEL_KEY for localStorage persistence
• Utility: Created getEffectiveCompactionModel() to manage the sticky preference
  • Saves model to localStorage when -m flag is used
  • Retrieves saved preference when no model specified
  • Falls back to workspace model when no preference exists
• Integration: Updated prepareCompactionMessage() in ChatInput to use new utility
• Tests: Added 6 comprehensive test cases with localStorage mocking
• Docs: Updated docs/context-management.md with sticky behavior explanation

Usage Example

# Set preference to haiku - becomes default
/compact -m haiku

# Future compactions automatically use haiku
/compact
/compact -t 5000

# Change preference to opus
/compact -m opus

# Now opus is the new default
/compact

Testing

✅ 6 new tests for preference management
✅ 34 existing compact command tests passing
✅ 7 compaction options tests passing
✅ TypeScript checks passing

Design Notes

• Global scope: Preference applies across all workspaces (matches UX expectation)
• Frontend-only: Uses localStorage pattern, not backend config (per project guidelines)
• Testable: Logic extracted to pure utility function with comprehensive tests
• Backwards compatible: No model specified still works (uses workspace default)

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