Optimize word of day fallback to single Swift invocation

[Copilot]

The fallback mechanism was invoking Swift 5 times in a loop (once per fallback word), incurring startup overhead of 100-300ms per invocation—up to 1.5s in worst case.

Changes:

• Consolidated fallback word lookup into single Swift invocation that iterates internally
• Swift returns first successful match with both word and definition
• Reduced worst-case overhead from 1-2s to ~100-300ms (5x improvement)

Implementation:

// Before: Shell loop with 5 separate Swift invocations
for fallback in "ephemeral" "serendipity" "eloquent" "resilient" "catalyst"; do
  definition=$(swift -e '...' -- "$fallback")
  [[ -n "$definition" ]] && word="$fallback" && break
done

// After: Single Swift invocation with internal iteration
fallback_result=$(swift -e '
let fallbackWords = ["ephemeral", "serendipity", "eloquent", "resilient", "catalyst"]
for word in fallbackWords {
    if let def = DCSCopyTextDefinition(...) {
        print(word)
        print("<<<DEFINITION_DELIMITER>>>")
        print(def)
        break
    }
}
')

Shell parsing uses delimiter-based awk patterns with explicit state tracking for robustness.

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.