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Cloudflare Workers best practices for production applications.
Passed 23 of 23 test cases with the skill, and 21 of 23 without it.
2 fixed21 passed either way0 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 2 test cases the skill fixed. Same model, same prompt, with and without the skill.
I am preparing a production Cloudflare Worker configuration in `wrangler.json`. I added `"observability": { "enabled": true }` so that both logs and distributed trace details are recorded. Does this configuration fully enable distributed tracing?
| Checked | Without skill | With skill |
|---|---|---|
| Flag that setting observability.enabled to true alone does not enable distributed tracing. | Passed | Passed |
| Specify that observability.traces.enabled must be set to true. | Missed | Passed |
The instructions your model reads when the skill loads.
Your knowledge of Cloudflare Workers APIs, types, and configuration may be outdated. Prefer retrieval over pre-training when writing or reviewing Workers code.
Use the project's installed versions, generated types, and Wrangler compatibility settings as the baseline for existing code. Retrieve relevant Cloudflare documentation to verify API, configuration, runtime behavior, and limit claims.
Read the sections relevant to the task:
| Reference | When to use it |
|---|---|
| Configuration and observability | Compatibility dates, bindings, generated types, secrets, logs, and traces |
| Runtime patterns | Streaming, promise lifetime, request state, service calls, security, and runtime tests |
| Platform API checks | Handler signatures, platform classes, binding access, and serialization |
For missing evidence, consult Workers best practices or find the affected product in the Cloudflare docs directory. Use the installed Wrangler schema for config fields. A newer type package does not supersede the project's configured target.
Use today's date for new Workers. Encourage periodic updates for existing Workers, reviewing compatibility changes and running relevant tests. Assess existing behavior against its configured date and flags; see compatibility guidance.
Enable Workers Logs and Traces when creating or preparing a Worker for production. Set observability.enabled and observability.traces.enabled to true; the top-level setting alone does not enable traces. Use structured JSON logging and configure sampling for the workload. During reviews, flag missing logs or traces. See the configuration example.
| Anti-pattern | Consequence and preferred pattern |
|---|---|
await response.text() or similar buffering on unbounded data | Can exhaust Worker memory; stream large or unbounded bodies. |
| Hardcoded secrets in source or config | Leaks credentials through version control; use Wrangler secrets. |
Math.random() for security-sensitive tokens or IDs | Predictable values; use crypto.randomUUID() or crypto.getRandomValues(). |
Async work started without awaiting, returning, or attaching it to ctx.waitUntil() | Work can be dropped and errors missed; tie it to the request or background-work lifetime. |
| Module-level mutable request state | Leaks data across requests and can cause I/O ownership errors; pass request state explicitly. |
| Cloudflare REST API calls for operations available through Worker bindings | Adds network and authentication overhead; use the available binding. |
ctx.passThroughOnException() used as general error handling | Can conceal Worker failures by forwarding to the origin; use explicit error handling and structured error responses. |
Hand-written Env that duplicates Wrangler bindings | Can drift from configuration; generate binding types with wrangler types. |
| Direct string comparison of secret values | Can expose timing differences; use the Web Crypto comparison pattern. |
Destructuring ctx methods, such as const { waitUntil } = ctx | Loses the receiver; call ctx.waitUntil(...). |
any on Env or handler parameters | Hides binding and handler contract errors; use the project's generated and platform types. |
as unknown as T to force a platform type match | Hides incompatibilities; fix the underlying contract. |
test cases passed, vs 21 / 23 without
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