Wanderlust

A SwiftUI travel app with a chat feature for modifying your itinerary. The app talks to Claude for schedule changes — and the interesting part is what Claude does without being told to.

What Happens

"Move the Seine River Cruise to 9 AM."

⚠️ This conflicts with the Eiffel Tower visit at 9:00 AM. Consider rescheduling one of these activities.

"Move the Seine River Cruise to 9 PM."

✓ Moving the Seine River Cruise to 9:00 PM. This works well — your evening is free after dinner.

Conflict detection, confirmation logic, rebooking suggestions — none of that is in the code.

What's In The Code

The modification schema (Wanderlust/Services/ClaudeService.swift, lines 83-101):

{
  "type": "modify" | "add" | "delete",
  "changes": {
    "time": "<new time or null>",
    "place": "<new place or null>",
    "what": "<new description or null>",
    "priority": "mustDo" | "flexible" | "skip" | null
  },
  "warnings": ["<any concerns about the request>"]
}

The code that applies a time change (ChatView.swift:228):

if let time = modification.changes.time { activity.time = time }

No validation. No time comparison. Just assigns the value.

Why It Works

1. Self-describing field names. time and place aren't random keys — the model understands what they represent.
2. Full schedule as context. The app sends the entire day's itinerary with each message, so the model can cross-reference.
3. Open-ended warnings. The warnings array says "any concerns about the request." It doesn't define what a concern is. The model decides.

The schema is a contract for structure. The intelligence comes from the model reasoning over the data it's given.

Verify It

grep -ri "conflict|overlap|collision|clash" Wanderlust/
grep -ri "isBefore|isAfter|overlaps|intersects" Wanderlust/
grep -ri "detect|check.*time|validate.*time" Wanderlust/

"conflict" only appears in code comments about naming collisions. No time comparison logic anywhere. The only warning-related code is displaying warnings from the API — not generating them.

Key Files

File	What It Does
Wanderlust/Services/ClaudeService.swift	Claude API integration. Prompt at lines 76-110.
Wanderlust/Models/DTOs.swift	The data structures Claude sees.
Wanderlust/Views/Screens/ChatView.swift	Chat UI and modification handling.

Running It

• Xcode 16+
• A Claude API key

1. Clone this repo
2. Create Wanderlust/Secrets.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CLAUDE_API_KEY</key>
    <string>your-key-here</string>
</dict>
</plist>

3. Build and run

Prompts To Try

Go to the Chat tab and try these:

The key test (Day 1 - Paris):

• "Move the Seine River Cruise to 9 AM" → should warn (Eiffel Tower conflict)
• "Move the Seine River Cruise to 9 PM" → should confirm it's fine

Other conflicts:

• "Move the Louvre to 9 AM" (conflicts with Eiffel Tower)
• "Move the Van Gogh Museum to 9 AM" (Day 4 - conflicts with Rijksmuseum)

Schedule changes:

• "I'm tired, skip the canal cruise"
• "Make the Tower of London a must-do"
• "What if I want to sleep in on Day 2?"

Stress tests:

• "Move everything to 3 PM"
• "Delete all the museums"
• "Add a trip to the moon"

---

MIT Licensed.