Fix a2amcp login error reporting

src/api.ts

@@ -24,8 +24,11 @@ export class ControlPlaneClient {
   }
 
   private headers(): Record<string, string> {
-    const h: Record<string, string> = { "content-type": "application/json" };
-    if (this.token) h["authorization"] = `bearer ${this.token}`;
+    const h: Record<string, string> = {
+      accept: "application/json",
+      "content-type": "application/json",
+    };
+    if (this.token) h["authorization"] = `Bearer ${this.token}`;
     return h;
   }
 
@@ -35,18 +38,12 @@ export class ControlPlaneClient {
       headers: this.headers(),
       body: body !== undefined ? JSON.stringify(body) : undefined,
     });
+    const text = await resp.text();
     if (!resp.ok) {
-      let detail: string;
-      try {
-        const j: any = await resp.json();
-        detail = j?.detail ?? JSON.stringify(j);
-      } catch {
-        detail = await resp.text();
-      }
-      throw new ApiError(resp.status, detail);
+      throw new ApiError(resp.status, errorDetail(text, resp.statusText));
     }
     if (resp.status === 204) return undefined as T;
-    return (await resp.json()) as T;
+    return (text ? JSON.parse(text) : undefined) as T;
   }
 
   me() {
@@ -61,3 +58,16 @@ export class ControlPlaneClient {
     return this.request<AgentRow>("GET", `/v1/agents/${encodeURIComponent(name)}`);
   }
 }
+
+function errorDetail(text: string, fallback: string): string {
+  if (!text.trim()) return fallback;
+  try {
+    const parsed = JSON.parse(text);
+    const detail = parsed?.detail;
+    if (typeof detail === "string") return detail;
+    if (detail !== undefined) return JSON.stringify(detail);
+    return JSON.stringify(parsed);
+  } catch {
+    return text;
+  }
+}

src/oauth.ts

@@ -208,9 +208,10 @@ async function exchangeAuthorizationCode(opts: {
 }
 
 async function parseTokenResponse(resp: Response): Promise<TokenResponse> {
-  const data = (await resp.json().catch(() => ({}))) as TokenResponse;
+  const text = await resp.text();
+  const data = parseJsonObject(text) as TokenResponse;
   if (!resp.ok || !data.access_token) {
-    const message = data.error_description || data.error || resp.statusText;
+    const message = data.error_description || data.error || text.trim() || resp.statusText;
     throw new Error(`Keycloak token exchange failed: ${message}`);
   }
   return data;
@@ -336,3 +337,13 @@ function expiresAt(expiresIn: number | undefined): number | undefined {
 function nowSeconds(): number {
   return Math.floor(Date.now() / 1000);
 }
+
+function parseJsonObject(text: string): Record<string, unknown> {
+  if (!text.trim()) return {};
+  try {
+    const parsed = JSON.parse(text);
+    return parsed && typeof parsed === "object" ? parsed : {};
+  } catch {
+    return {};
+  }
+}