Event Handling: Engineering for Vibe Coders
Many vibe-coded prototypes work fine when everything happens in a straight line. A user clicks a button, the app responds, and life is good. But real applications are event-driven. Users click, APIs respond late, models finish processing, timers fire, and messages arrive out of order.
Event handling is about designing how your system reacts when something happens. Planning this early prevents fragile logic, missed updates, and confusing bugs once your prototype becomes interactive or asynchronous.
1. What is an event?
An event is a signal that something has happened in your system.
Common examples:
- A user clicks a button
- An API call returns
- A background job finishes
- A message arrives from a queue
- A timer or scheduled task fires
Events trigger logic, update state, or start new work. Without a clear plan, event-driven code quickly turns into tangled conditionals and unexpected side effects.
🟢 Pre-prototype habit:
List the events your prototype must respond to. Focus on actions, not features. Write them as “When X happens, then Y should occur.”
2. Event-driven vs sequential thinking
Many non-developers think in linear steps:
- Do this
- Then do that
- Then return a result
Event-driven systems do not behave this way. Events can:
- Arrive out of order
- Fire multiple times
- Trigger other events
- Occur while other work is still running
This is especially common in AI apps with async calls, streaming responses, or background processing.
🟢 Pre-prototype habit:
Draw a simple flow showing which events can happen independently and which must wait for others. Do not assume everything happens in sequence.
3. Handling events safely
Poor event handling often causes:
- Duplicate actions
- Lost updates
- Inconsistent state
- UI that gets out of sync with data
Good event handling practices include:
- Making event handlers small and focused
- Avoiding side effects scattered across the app
- Ensuring repeated events are safe to process
- Clearly defining what state an event is allowed to modify
🟢 Pre-prototype habit:
For each event, write down what data it can read and what data it can change. If this feels unclear, the design probably is.
4. Events, state, and idempotency
Events rarely exist alone. They interact closely with state and idempotency.
Key considerations:
- Events often update shared state
- The same event may fire more than once
- Event handling should be safe to retry
- State updates should be predictable and repeatable
Without these rules, event-driven prototypes behave differently depending on timing and load.
🟢 Pre-prototype habit:
Decide whether handling the same event twice should change the outcome. If not, plan idempotent handling from the start.
5. Lightweight event handling for prototypes
You do not need complex frameworks to start. For early prototypes:
- Use clear event names and handlers
- Keep handlers small and testable
- Log when events occur and how they are handled
- Avoid deeply nested event chains
Many AI frameworks already use event-based patterns internally. Understanding the basics helps you use them correctly.
🟢 Pre-prototype habit:
Name your events explicitly and sketch which component handles each one. Avoid “magic” behavior that is hard to trace later.
6. Quick pre-prototype checklist
| Checklist Item | Why It Matters |
|---|---|
| Identify all key events | Prevents missing important triggers |
| Separate events from sequential logic | Avoids fragile assumptions |
| Define event responsibilities | Prevents side effects |
| Plan idempotent event handling | Makes retries safe |
| Log event flow | Makes debugging possible |
Closing note
Event handling is one of the biggest shifts from simple scripts to real applications. AI prototypes that ignore events often break as soon as they become interactive, asynchronous, or multi-user.
🟢 Pre-prototype habit:
Before writing code, list your events, define what they can change, and plan how they interact with state. Clear event design early keeps your prototype stable, understandable, and ready to grow.
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