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Infrastructure advanced 40 min

Worker Service

Build a Cloudflare Worker that composes cleanly with other services.

Objectives

  • Design a clean service interface
  • Implement proper error handling
  • Use service bindings for composition
  • Follow gateway pattern principles

Beads Tasks

Create these tasks in Beads before starting. You learn Beads by using Beads.

bd create "Praxis: Build [service] Worker" --type=feature--labels=learn,infrastructure
bd create "Design service interface (inputs, outputs, errors)" --type=task--labels=learn
bd create "Implement core handler logic" --type=task--labels=learn
bd create "Add error handling with proper HTTP semantics" --type=task--labels=learn
bd create "Configure service bindings for composition" --type=task--labels=learn
bd create "Test end-to-end with wrangler dev" --type=task--labels=learn

Claude Code Prompt

Copy this prompt into Claude Code to build YOUR own version:

## Setup: Track this exercise with Beads

```bash
bd create "Praxis: Build [service] Worker" --type=feature --labels=learn,infrastructure
bd create "Design service interface (inputs, outputs, errors)" --type=task --labels=learn
bd create "Implement core handler logic" --type=task --labels=learn
bd create "Add error handling with proper HTTP semantics" --type=task --labels=learn
bd create "Configure service bindings for composition" --type=task --labels=learn
bd create "Test end-to-end with wrangler dev" --type=task --labels=learn
```

---

Help me build a Cloudflare Worker for [SERVICE_NAME] following MY service composition patterns.

I'm defining MY approach to edge services. For [SERVICE_NAME]:

1. **Design the service interface**:
   - What are the inputs (request shape, query params, headers)?
   - What are the outputs (response shape, status codes)?
   - What errors can occur and how are they represented?
   - Create a TypeScript interface for Request/Response

2. **Implement the handler**:
   - Parse and validate inputs
   - Execute core logic
   - Return structured responses
   - Use proper HTTP semantics (GET for reads, POST for mutations)

3. **Error handling strategy**:
   - Map internal errors to HTTP status codes
   - Return consistent error response shape
   - Log appropriately for observability

4. **Composition with bindings**:
   - What other services does this need? (D1, KV, R2, other Workers)
   - Configure wrangler.toml bindings
   - Use service bindings for Worker-to-Worker calls

5. **Document MY service patterns**:
   - Naming conventions for Workers
   - Standard response envelope shape
   - Error handling philosophy

Service to build: [YOUR_SERVICE_NAME]
Purpose: [WHAT_IT_DOES]
Bindings needed: [D1/KV/R2/OTHER_WORKERS]

Your Solution

Write code that addresses the objectives above. Apply the principles from the Infrastructure path.

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