fix: gate login result text on error state (#1103)

## Summary
- Fixes #1092 by treating `Please run /login` in a `success` result as
auth-required only when the result is actually error-shaped.
- Applies the same error-state guard to goal-command failure detection
so quoted login text in a normal answer does not roll back the active
goal.
- Adds a regression test for a successful model answer that mentions
`/login` without publishing a session failure.

## Test Plan
- [x] `npm run test:run -- src/tests/acp-agent.test.ts -t
'login|auth_required'`
- [x] `npm run build`
- [x] `npm run check`
- [ ] `npm run test:run` (blocked locally by pre-existing root
permission-mode assertions: `resolvePermissionMode("bypassPermissions")`
and `resolvePermissionMode("bypass")` resolve to `default` when running
as root)

Signed-off-by: Emre K <110906681+kocaemre@users.noreply.github.com>

src/acp-agent.ts

@@ -5042,7 +5042,9 @@ export class ClaudeAcpAgent {
                   const goalCommandFailed =
                     message.is_error ||
                     message.stop_reason === "refusal" ||
-                    ("result" in message && message.result.includes("Please run /login"));
+                    ("result" in message &&
+                      message.is_error &&
+                      message.result.includes("Please run /login"));
                   if (goalCommandFailed) {
                     await this.publishGoal(params.sessionId, pendingGoalUpdate.previous ?? null);
                   }
@@ -5406,7 +5408,7 @@ export class ClaudeAcpAgent {
 
               switch (message.subtype) {
                 case "success": {
-                  if (message.result.includes("Please run /login")) {
+                  if (message.is_error && message.result.includes("Please run /login")) {
                     await failActiveWithSessionFailure(
                       "auth_required",
                       RequestError.authRequired(),

src/tests/acp-agent.test.ts

@@ -7439,6 +7439,35 @@ describe("stop reason propagation", () => {
     expect(logged.join("\n")).not.toContain("cannot fail active turn");
   });
 
+  it("does not treat a successful answer mentioning /login as auth_required", async () => {
+    const updates: SessionNotification[] = [];
+    const agent = new ClaudeAcpAgent(
+      {
+        sessionUpdate: async (update: SessionNotification) => {
+          updates.push(update);
+        },
+      } as unknown as AcpClient,
+      { log: () => {}, error: () => {} },
+    );
+    (agent as any).clientCapabilities = airSessionFailureCapabilities;
+    const answer = "A normal answer can quote: Please run /login.";
+    injectSession(agent, [
+      createAssistantError(undefined, answer),
+      createResultMessage({
+        subtype: "success",
+        stop_reason: "end_turn",
+        is_error: false,
+        result: answer,
+      }),
+      { type: "system", subtype: "session_state_changed", state: "idle" },
+    ]);
+
+    await expect(
+      agent.prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "test" }] }),
+    ).resolves.toMatchObject({ stopReason: "end_turn" });
+    expect(sessionFailuresFromUpdates(updates)).toEqual([]);
+  });
+
   it("republishes the signed-out state after a real model answer cleared the last one", async () => {
     const updates: SessionNotification[] = [];
     const agent = new ClaudeAcpAgent(