adapt error classification and email state to the lex session core

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/lib/__tests__/lex-error-test.ts

@@ -0,0 +1,54 @@
+import {XrpcResponseError} from '@atproto/lex-client'
+import {LexAuthFactorError} from '@atproto/lex-password-session'
+import {describe, expect, it} from '@jest/globals'
+
+import {getErrorName} from '../lex-error'
+
+/**
+ * A stand-in for the method schema an `XrpcResponseError` is built against.
+ * The generated lexicons are not available yet, and `XrpcResponseError` only
+ * reads `method` back out for `matchesSchemaErrors()`, which these tests never
+ * call - so a minimal object is enough.
+ */
+const method = {
+  nsid: 'com.atproto.server.createSession',
+  type: 'procedure',
+  errors: ['AuthFactorTokenRequired'],
+} as unknown as ConstructorParameters<typeof XrpcResponseError>[0]
+
+/** An error as the lex client builds one from a JSON error response body. */
+function xrpcResponseError(error: string, message: string) {
+  return new XrpcResponseError(method, new Response(null, {status: 400}), {
+    encoding: 'application/json',
+    body: {error, message},
+  })
+}
+
+describe('getErrorName', () => {
+  it('returns the lexicon error code of an XRPC response error', () => {
+    const e = xrpcResponseError('InvalidToken', 'Bad token scope')
+    expect(getErrorName(e)).toBe('InvalidToken')
+  })
+
+  it('returns AuthFactorTokenRequired for a LexAuthFactorError', () => {
+    /*
+     * The 2FA case: `PasswordSession.login` throws this, and it extends
+     * `LexError` WITHOUT being an `XrpcError` - the reason `getErrorName` is
+     * gated on `LexError`.
+     */
+    const cause = xrpcResponseError(
+      'AuthFactorTokenRequired',
+      'A sign in code has been sent to your email address',
+    )
+    expect(getErrorName(new LexAuthFactorError(cause))).toBe(
+      'AuthFactorTokenRequired',
+    )
+  })
+
+  it('returns undefined for non-lex errors', () => {
+    expect(getErrorName(new Error('InvalidToken'))).toBeUndefined()
+    expect(getErrorName('InvalidToken')).toBeUndefined()
+    expect(getErrorName(null)).toBeUndefined()
+    expect(getErrorName(undefined)).toBeUndefined()
+  })
+})

src/lib/lex-error.ts

@@ -0,0 +1,13 @@
+import {LexError} from '@atproto/lex-client'
+
+/**
+ * The lexicon error code (`err.error`). Gated on `LexError` (the base of the
+ * lex error hierarchy) rather than `XrpcError` so sibling `LexError` subclasses
+ * that are NOT `XrpcError` also surface their `.error` - notably
+ * `LexAuthFactorError` (`'AuthFactorTokenRequired'`), which `PasswordSession`
+ * throws for email-2FA logins. Every `XrpcError` is a `LexError`, so gating on
+ * the base covers server error responses too.
+ */
+export function getErrorName(e: unknown): string | undefined {
+  return e instanceof LexError ? e.error : undefined
+}