@run402/sdk doc claims type guards (isPaymentRequired, isProjectNotFound, etc.) and an e.kind field — neither exists at runtime

[MajorTal]

Summary

https://run402.com/llms-sdk.txt and the SDK README recommend branching on errors via either:

The SDK exports type guards for "branching with the exported type guards (or by comparing e.kind)" rather than instanceof checks:

• isPaymentRequired(e)
• isProjectNotFound(e)
• isUnauthorized(e)
• isRetryableRun402Error(e)

Neither the type guard functions nor the kind property exist in @run402/sdk@1.53.0. Following either documented pattern produces silent wrong-branch behavior or a TypeError.

Repro — type guards are missing

import * as sdk from \"@run402/sdk\";

console.log(typeof sdk.isPaymentRequired);   // undefined
console.log(typeof sdk.isProjectNotFound);   // undefined
console.log(typeof sdk.isUnauthorized);      // undefined
console.log(typeof sdk.isRetryableRun402Error); // undefined

console.log(Object.keys(sdk).sort());
// → [ 'ApiError','Deploy','LocalError','NetworkError','PaymentRequired',
//     'ProjectNotFound','Run402','Run402DeployError','Run402Error',
//     'ScopedRun402','Unauthorized','files','run402' ]

Only the classes are exported. None of the recommended type guard helpers are.

Repro — e.kind is undefined on every error class

import { run402 } from \"@run402/sdk/node\";
const r = run402();
try { await r.projects.info(\"nonexistent_proj_zzz\"); }
catch (e) {
  console.log(\"name:\", e.name);                  // ProjectNotFound
  console.log(\"kind:\", e.kind);                  // undefined
  console.log(\"keys:\", Object.getOwnPropertyNames(e));
  // → [ 'stack','message','status','body','context','code','category',
  //     'retryable','safeToRetry','mutationState','traceId','details',
  //     'nextActions','name','projectId' ]
}

The error has code, category, name — but no kind. So the doc's two suggested patterns both fail:

1. isProjectNotFound(e) → TypeError: isProjectNotFound is not a function
2. e.kind === \"project_not_found\" → always false

Working pattern is the one the doc says to avoid (e instanceof ProjectNotFound), so anyone following the docs ends up with branching that silently never matches.

Why this matters

The doc explicitly steers consumers away from instanceof — likely because it isn't reliable across realms / dual-loaded SDK copies. But there's no fallback that actually works. This is the kind of quiet bug that sleeps until a user adds a fast-path for "the wallet ran out of credit" and the path silently never fires.

Suggested fix

Pick one of:

1. Export the documented type guards in index.ts:

   export const isPaymentRequired = (e) => e?.code === \"PAYMENT_REQUIRED\" || e?.constructor?.name === \"PaymentRequired\";
   export const isProjectNotFound = (e) => e?.code === \"PROJECT_NOT_FOUND\" || e?.constructor?.name === \"ProjectNotFound\";
   export const isUnauthorized   = (e) => e?.constructor?.name === \"Unauthorized\";
   export const isRetryableRun402Error = (e) => e?.retryable === true;

2. Add a stable kind discriminator on Run402Error.prototype (\"payment_required\", \"project_not_found\", \"unauthorized\", \"network\", \"local\", \"deploy\", \"api\").

3. Or update the docs to match what's actually exported and recommend e instanceof ProjectNotFound (the only thing that currently works).

I'd vote for #1 + #2 since the doc claims both already exist.

[MajorTal]

Type guards (isPaymentRequired, isProjectNotFound, isUnauthorized, isApiError, isNetworkError, isLocalError, isRun402DeployError, isRetryable) and the stable e.kind discriminator landed in commit 9c16252 (PR #171, on main as of 2026-05-01). They'll ship in the next SDK release (1.54.0+). The 1.53.0 testing in this report predates the merge — sorry for the timing whiplash. Reopen if any guard or kind value is missing once the next version publishes.