fix(kiro): route IdC auth to regional CodeWhisperer surface (#2297)

IAM Identity Center (authMethod=idc) tokens failed every request with 403
"bearer token invalid". Treat idc like api_key/external_idp:

- executors/kiro.js: route idc to *.amazonaws.com CodeWhisperer surface,
  region-aware from credentials.region instead of hardcoded us-east-1.
- openai-to-kiro.js / claude-to-kiro.js: send resolved profileArn or empty
  for idc/external_idp, never the shared builder-id placeholder ARN.

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/executors/kiro.js

@@ -64,9 +64,22 @@ export class KiroExecutor extends BaseExecutor {
   getOrderedBaseUrls(credentials) {
     const baseUrls = this.getBaseUrls();
     const authMethod = credentials?.providerSpecificData?.authMethod;
-    const isCodeWhispererSurface = authMethod === "api_key" || authMethod === "external_idp";
+    // IAM Identity Center (idc) tokens are AWS SSO access tokens — the same
+    // family as external_idp/api_key. The kiro.dev gateway rejects them with
+    // 403 "bearer token invalid", so they must hit the CodeWhisperer
+    // *.amazonaws.com surface, and in the region the token was minted in
+    // (the baseUrls are hardcoded us-east-1).
+    const isCodeWhispererSurface =
+      authMethod === "api_key" || authMethod === "external_idp" || authMethod === "idc";
     if (!isCodeWhispererSurface) return baseUrls;
-    const amazon = baseUrls.filter((u) => u.includes("amazonaws.com"));
+
+    const region = (credentials?.providerSpecificData?.region || "us-east-1").trim();
+    const regionalize = (u) =>
+      region && region !== "us-east-1" && u.includes("amazonaws.com")
+        ? u.replace(/([a-z]+)\.[a-z0-9-]+\.amazonaws\.com/, `$1.${region}.amazonaws.com`)
+        : u;
+
+    const amazon = baseUrls.filter((u) => u.includes("amazonaws.com")).map(regionalize);
     const others = baseUrls.filter((u) => !u.includes("amazonaws.com"));
     return amazon.length > 0 ? [...amazon, ...others] : baseUrls;
   }

open-sse/translator/request/claude-to-kiro.js

@@ -393,9 +393,12 @@ export function claudeToKiroRequest(model, body, stream, credentials) {
     reconcileOrphanedToolResults(history, currentMessage);
   }
 
-  // API-key auth must never use the shared default ARN (403); OAuth/social fall back to it.
+  // api_key / idc / external_idp must never use the shared default ARN (belongs
+  // to another account → 403 "bearer token invalid"); OAuth/social fall back to it.
   const authMethod = credentials?.providerSpecificData?.authMethod;
-  const profileArn = authMethod === "api_key"
+  const accountBoundAuth =
+    authMethod === "api_key" || authMethod === "idc" || authMethod === "external_idp";
+  const profileArn = accountBoundAuth
     ? (credentials?.providerSpecificData?.profileArn || "")
     : (credentials?.providerSpecificData?.profileArn || resolveDefaultProfileArn(authMethod));
 

open-sse/translator/request/openai-to-kiro.js

@@ -530,8 +530,15 @@ export function openaiToKiroRequest(model, body, stream, credentials) {
   // (the ARN doesn't belong to the key's account). So for api_key, only send a
   // profileArn that was actually resolved for this connection — never the default.
   // OAuth/social keep the default fallback (their tokens accept it).
+  // api_key / idc / external_idp carry an account-specific (or token-bound)
+  // profile. The shared builder-id/social default ARN belongs to a different
+  // account and triggers 403 "bearer token invalid", so never fall back to it —
+  // send the resolved ARN, or an empty string so CodeWhisperer uses the token's
+  // own default profile. Only OAuth/social keep the shared placeholder.
   const authMethod = credentials?.providerSpecificData?.authMethod;
-  const profileArn = authMethod === "api_key"
+  const accountBoundAuth =
+    authMethod === "api_key" || authMethod === "idc" || authMethod === "external_idp";
+  const profileArn = accountBoundAuth
     ? (credentials?.providerSpecificData?.profileArn || "")
     : (credentials?.providerSpecificData?.profileArn || resolveDefaultProfileArn(authMethod));