MCP Time Server Node

# Verified Behavior: resolveTimezone Utility **Decision Date:** 2025-01-31 15:45 EST ## Purpose Standardize timezone resolution across all tools following the project's critical convention. ## Verified Behavior The `resolveTimezone` utility implements the following behavior: ### Core Logic ```typescript function resolveTimezone(timezone: string | undefined, defaultTimezone: string): string { if (timezone === '') return 'UTC'; return timezone ?? defaultTimezone; } ``` ### Input/Output Mapping | Input | Output | Rationale | |-------|--------|-----------| | `undefined` | `defaultTimezone` (system local) | User didn't specify, use their system default | | `""` (empty string) | `"UTC"` | Explicit request for UTC | | `"America/New_York"` | `"America/New_York"` | Specific timezone requested | | `null` (edge case) | `defaultTimezone` | Treated as undefined (shouldn't occur in TypeScript) | ## Implementation Requirements 1. **Must use explicit empty string check**: `timezone === ''` not `!timezone` or `timezone || default` - Empty string is falsy but has special meaning (UTC) - Using `||` operator would incorrectly treat `""` as undefined 2. **Must use nullish coalescing**: `timezone ?? defaultTimezone` not `timezone || defaultTimezone` - Preserves empty string handling - Correctly handles undefined 3. **No validation in base utility**: Timezone validation happens elsewhere - Keep utility focused on single responsibility - Validation is handled by `parseTimeInput` or specific tools ## Current Duplication Research found this pattern duplicated across: - 7 tools using inline resolution - 4 tools with their own `resolveTimezone` functions (each slightly different) ## Benefits of Extraction 1. **Consistency**: Single source of truth for critical timezone convention 2. **Maintainability**: Change behavior in one place if needed 3. **Quality**: Reduce chance of implementation errors (like using `||` instead of `??`) 4. **Clarity**: Named function makes intent explicit ## Test Coverage The utility must be tested for: - `undefined` input → returns default timezone - Empty string input → returns "UTC" - Specific timezone string → returns that string unchanged - Type safety with TypeScript ## Migration Notes When applying to existing tools: 1. Remove inline resolution logic 2. Import `resolveTimezone` from utils 3. Replace with single function call 4. Ensure variable names remain consistent (some use `effectiveTimezone`)