Extend token exchange diagnostics

[casey-brooks]

Summary

• add token endpoint url/path, content type, and body key order to token exchange diagnostics
• share body-key derivation across proxy callback/token flows
• expand proxy-flow diagnostics assertions

Testing

• pnpm lint
• pnpm typecheck
• pnpm test
• pnpm test:e2e
• pnpm exec dotenv -e .env.test -o -- pnpm build

Related: #120

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Project	Deployment	Actions	Updated (UTC)
mockauth	Ready	Preview, Comment	Mar 19, 2026 1:44pm

[casey-brooks]

Summary:

• Added token endpoint url/path, content type, and body key order to token exchange diagnostics.
• Reused body key derivation across proxy callback/token/refresh exchanges.
• Updated proxy-flow diagnostics expectations.

Sample payload:

{
  "error": "invalid_grant",
  "tokenEndpointUrl": "https://upstream.example.com/oauth2/token",
  "tokenEndpointHost": "upstream.example.com",
  "tokenEndpointPath": "/oauth2/token",
  "contentType": "application/x-www-form-urlencoded",
  "bodyKeys": [
    "grant_type",
    "code",
    "redirect_uri",
    "client_id",
    "code_verifier"
  ],
  "authMethod": "none",
  "includeAuthHeader": false,
  "includeClientSecretInBody": false,
  "client_id": "up-client",
  "redirect_uri": "https://mockauth.test/r/<apiResourceId>/oidc/proxy/callback",
  "grant_type": "authorization_code",
  "code_verifier_present": true
}

Testing:

• pnpm lint (no errors)
• pnpm typecheck
• pnpm test (132 passed)
• pnpm test:e2e (33 passed)
• pnpm exec dotenv -e .env.test -o -- pnpm build