Debug

Stack Debugging

Troubleshoot @outfitter/* package issues.

Result Issues

Always Getting Error

Symptom: Result is err when it should be ok.

Check validation:

const inputResult = validateInput(rawInput);
if (inputResult.isErr()) {
  console.log("Validation failed:", inputResult.error.context);
  return inputResult;
}

Check async:

// BAD: Missing await
const result = getUser(id); // Promise, not Result!

// GOOD
const result = await getUser(id);

Type Narrowing Broken

Symptom: TypeScript doesn't know type after isOk().

// BAD: Reassigning breaks narrowing
let result = await getUser(id);
if (result.isOk()) {
  result = await updateUser(result.value); // Breaks!
}

// GOOD: Separate variables
const getResult = await getUser(id);
if (getResult.isErr()) return getResult;
const updateResult = await updateUser(getResult.value);

Error Type Lost

Use _tag for narrowing:

if (result.isErr()) {
  switch (result.error._tag) {
    case "ValidationError":
      console.log(result.error.context);
      break;
    case "NotFoundError":
      console.log(result.error.resourceId);
      break;
  }
}

MCP Issues

Tool Not Appearing

1. Register before start():

   server.registerTool(myTool);
   server.start(); // After registration!
   

2. Check schema is valid Zod with .describe():

   const schema = z.object({
     query: z.string().describe("Required for AI"),
   });
   

Tool Invocation Failing

1. Verify handler is async:

   handler: async (input) => {
     // Not sync!
     return Result.ok(data);
   };
   

2. Return Result, not raw value:

   // BAD
   return { data: "value" };
   
   // GOOD
   return Result.ok({ data: "value" });
   

CLI Output Issues

JSON Not Printing

1. Force mode:

   await output(data, { mode: "json" });
   

2. Check environment:

   OUTFITTER_JSON=1 myapp list
   OUTFITTER_JSON=0 myapp list --json  # Forces human!
   

3. Await output:

   // BAD
   output(data);
   process.exit(0); // May exit before output!
   
   // GOOD
   await output(data);
   

Wrong Exit Code

1. Use exitWithError:

   // BAD
   process.exit(1);
   
   // GOOD
   exitWithError(result.error);
   

2. Exit code table:

   Category	Exit
   validation	1
   not_found	2
   conflict	3
   permission	4
   timeout	5
   rate_limit	6
   network	7
   internal	8
   auth	9
   cancelled	130

Logging Issues

Redaction Not Working

const logger = createLogger({
  redaction: { enabled: true }, // Must be true!
});

// Custom patterns
const logger = createLogger({
  redaction: {
    enabled: true,
    patterns: ["password", "apiKey", "myCustomSecret"],
  },
});

Missing Context

import { createChildLogger } from "@outfitter/logging";

const requestLogger = createChildLogger(ctx.logger, {
  requestId: ctx.requestId,
  handler: "myHandler",
});

requestLogger.info("Processing", { data }); // Includes requestId

Wrong Level

const logger = createLogger({
  level: process.env.LOG_LEVEL || "info",
});

// Hierarchy: trace < debug < info < warn < error < fatal
// "info" hides trace and debug

Debugging Tools

Trace Result Chain

function traceResult<T, E>(name: string, result: Result<T, E>): Result<T, E> {
  console.log(
    `[${name}]`,
    result.isOk() ? "OK:" : "ERR:",
    result.isOk() ? result.value : result.error
  );
  return result;
}

const result = traceResult("getUser", await getUser(id));

Inspect Context

console.log("Context:", {
  requestId: ctx.requestId,
  hasLogger: !!ctx.logger,
  hasConfig: !!ctx.config,
  hasSignal: !!ctx.signal,
  cwd: ctx.cwd,
});

Validate Zod Schema

const parseResult = schema.safeParse(rawInput);
if (!parseResult.success) {
  console.log("Zod errors:", parseResult.error.issues);
}

Related Skills

• stack:patterns — Correct patterns
• stack:review — Systematic audit
• stack:outfitter-testing — Prevent regressions