This is part 1 of a series on building production-ready infrastructure. Written in collaboration with Claude Code, who helped debug the very issue we're dissecting here.
I've been building serverless applications long enough to know that deployment failures come in many flavors. But last week, Claude and I encountered one of the most insidious types: the silent TypeScript compilation failure that breaks production while reporting success.
Here's what happened, how we debugged it, and why this particular failure mode is so dangerous in serverless environments.
The Setup: AI Agent APIs That Wouldn't Deploy
We were building comprehensive AI agent infrastructure for this blog—a capabilities discovery API, health monitoring, feedback systems, the works. Everything was committing cleanly, GitHub Actions were green, and new functions were deploying successfully.
But one critical endpoint was stuck in time.
## This worked perfectly
curl https://haasonsaas.com/api/health
## Fresh timestamp, all features working
## This was frozen in the past
curl https://haasonsaas.com/api/capabilities
## Timestamp from an hour ago, missing new features
New functions deployed fine. Modified functions were silently failing.
## The Misdirection: When Everything Looks Fine
The routing table showed our function was registered:
```json
{
"routePath": "/api/capabilities",
"mountPath": "/api",
"method": "",
"module": ["api/capabilities.ts:onRequest"]
}
GitHub Actions reported success. No error logs in Cloudflare. The function was there—it just wasn't updating.
This is where most debugging goes wrong. You start questioning your deployment pipeline, checking cache headers, wondering if Cloudflare has regional deployment lag.
## The Breakthrough: Testing TypeScript Compilation
Claude suggested something I should have tried immediately:
```bash
bun --bun tsc --noEmit functions/api/capabilities.ts
Boom:
functions/api/capabilities.ts(43,42): error TS2304: Cannot find name 'EventContext'.
functions/api/capabilities.ts(43,55): error TS2304: Cannot find name 'Env'.
**The function had TypeScript compilation errors that prevented deployment, but Cloudflare Pages was failing silently.**
## The Root Cause: Missing Interfaces
Looking at the problematic code:
```typescript
// This was missing entirely
interface Env {
[key: string]: unknown
}
// This was using an undefined type
export async function onRequest(
context: EventContext<Env, string, Record<string, unknown>>
): Promise<Response> {
// Function body...
}
The working functions all had proper `Env` interfaces and correct type definitions. This one was missing both.
In a traditional Node.js environment, this would fail fast with clear error messages. In Cloudflare's serverless environment, it fails silently while reporting deployment success.
## Why This Failure Mode Is So Dangerous
**1. False Confidence**
Your CI/CD pipeline shows green. Your deployment appears successful. You assume everything is working.
**2. Partial Failures**
New functions deploy correctly while modified functions silently fail. This creates inconsistent behavior that's hard to trace.
**3. No Error Visibility**
Unlike traditional servers where compilation errors are immediately visible, serverless platforms often abstract away the compilation step.
**4. Time-Delayed Discovery**
You might not notice the issue until users report problems, especially if the broken function isn't in your critical path.
## The Debugging Process That Actually Works
### Step 1: Test TypeScript Compilation Locally
Don't trust your deployment pipeline. Test compilation explicitly:
```bash
## Test individual functions
bun --bun tsc --noEmit functions/api/problematic-function.ts
## Test entire functions directory
bun --bun tsc --noEmit functions/**/*.ts
### Step 2: Compare Working vs Broken Functions
Look at functions that deploy successfully and compare their structure:
```typescript
// Working function structure
interface Env {
[key: string]: unknown
}
export async function onRequest(context: {
request: Request
env: Env
}): Promise<Response> {
// Implementation
}
### Step 3: Check Your Function Signatures
Cloudflare Pages Functions expect specific signatures. Using the wrong types can cause silent failures:
```typescript
// This works
context: {
request: Request
env: Env
}
// This might cause issues depending on your setup
context: EventContext<Env, string, Record<string, unknown>>
### Step 4: Validate with Fresh Timestamps
Use timestamp checks to verify actual deployment:
```typescript
const response = {
lastUpdated: new Date().toISOString(), // Should be fresh on every deploy
}
## The Deeper Problem: Serverless Abstraction Tax
This incident highlights a broader issue with serverless platforms. The abstraction that makes them powerful—automatic scaling, managed infrastructure, simplified deployment—also hides crucial feedback loops.
Traditional deployment gives you:
- Immediate compilation feedback
- Clear error messages
- Obvious failure points
Serverless deployment gives you:
- Opaque build processes
- Silent failures
- Success indicators that don't guarantee functionality
## Prevention Strategies
### 1. Local TypeScript Validation
Add this to your pre-commit hooks:
```bash
## .husky/pre-commit
bun --bun tsc --noEmit functions/**/*.ts
### 2. Deployment Health Checks
Build verification into your deployment process:
```bash
## Verify functions are actually updated
curl https://yoursite.com/api/health | jq '.timestamp'
### 3. Function Template Consistency
Standardize your function structure:
```typescript
// Standard template
interface Env {
[key: string]: unknown
}
export async function onRequest(context: {
request: Request
env: Env
}): Promise<Response> {
// Your logic here
}
### 4. Canary Testing
Test functions immediately after deployment:
```bash
## Basic smoke test
for endpoint in /api/capabilities /api/health /api/search; do
echo "Testing $endpoint..."
curl -f "https://yoursite.com$endpoint" || echo "FAILED"
done
## What This Teaches Us About Modern Development
This debugging session revealed something important about the current state of web development. We're building increasingly complex systems on top of abstractions that can fail in non-obvious ways.
The solution isn't to avoid serverless platforms—they're incredibly powerful. It's to understand their failure modes and build appropriate safeguards.
**Key takeaways:**
1. **Silent failures are the worst failures.** They give you false confidence while breaking user experience.
1. **Local validation saves production pain.** TypeScript compilation should be tested locally, not discovered in production.
1. **Serverless platforms need different debugging approaches.** Traditional server debugging techniques don't always apply.
1. **Human-AI collaboration excels at systematic debugging.** Claude's suggestion to test TypeScript compilation directly led to the breakthrough.
## The Fix and Moving Forward
The actual fix was straightforward once we identified the root cause:
```typescript
// Add missing interface
interface Env {
[key: string]: unknown
}
// Fix function signature
export async function onRequest(context: {
request: Request
env: Env
}): Promise<Response> {
// Function implementation
}
But the debugging process took over an hour because we were looking in the wrong places. The failure was silent, the symptoms were confusing, and the root cause was hidden behind serverless abstractions.
This is part of a larger trend I'm seeing: as our development tools become more sophisticated, the failure modes become more subtle. The challenge isn't just building features—it's building systems that fail loudly and obviously when they break.
---
*Next in this series: "[Building for Humans AND Machines: The Dual-Audience Problem](/posts/building-for-humans-and-machines-the-dual-audience-problem)" - exploring how designing for both human users and AI agents creates unique UX and architectural challenges.*
*This post was written in collaboration with Claude Code, whose systematic debugging approach helped solve the very problem we're analyzing. Human-AI collaboration isn't just useful for building features—it's transforming how we approach complex technical problems.*