From 8cd86541ca8b9a2f59a884a5ec0d112de95319b6 Mon Sep 17 00:00:00 2001
From: Alessandro Pogliaghi <alessandro@posthog.com>
Date: Thu, 2 Apr 2026 10:52:31 +0100
Subject: [PATCH] fix(cloud): avoid recursive SSE failures

---
 packages/agent/src/server/agent-server.ts     | 23 ++++---
 .../agent/src/server/question-relay.test.ts   | 65 +++++++++++++++++++
 2 files changed, 80 insertions(+), 8 deletions(-)

diff --git a/packages/agent/src/server/agent-server.ts b/packages/agent/src/server/agent-server.ts
index 76f537fe6..bafd1fdf1 100644
--- a/packages/agent/src/server/agent-server.ts
+++ b/packages/agent/src/server/agent-server.ts
@@ -169,6 +169,12 @@ export class AgentServer {
   private initializationPromise: Promise<void> | null = null;
   private pendingEvents: Record<string, unknown>[] = [];
 
+  private detachSseController(controller: SseController): void {
+    if (this.session?.sseController === controller) {
+      this.session.sseController = null;
+    }
+  }
+
   private emitConsoleLog = (
     level: LogLevel,
     _scope: string,
@@ -250,18 +256,15 @@ export class AgentServer {
                 controller.enqueue(
                   new TextEncoder().encode(`data: ${JSON.stringify(data)}\n\n`),
                 );
-              } catch (error) {
-                this.logger.debug(
-                  "SSE send failed (stream may be closed)",
-                  error,
-                );
+              } catch {
+                this.detachSseController(sseController);
               }
             },
             close: () => {
               try {
                 controller.close();
-              } catch (error) {
-                this.logger.debug("SSE close failed (already closed)", error);
+              } catch {
+                this.detachSseController(sseController);
               }
             },
           };
@@ -1577,6 +1580,10 @@ Important:
   }
 
   private sendSseEvent(controller: SseController, data: unknown): void {
-    controller.send(data);
+    try {
+      controller.send(data);
+    } catch {
+      this.detachSseController(controller);
+    }
   }
 }
diff --git a/packages/agent/src/server/question-relay.test.ts b/packages/agent/src/server/question-relay.test.ts
index b4d95dfc4..bdac3891f 100644
--- a/packages/agent/src/server/question-relay.test.ts
+++ b/packages/agent/src/server/question-relay.test.ts
@@ -235,6 +235,71 @@ describe("Question relay", () => {
 
         expect(result.outcome.outcome).toBe("selected");
       });
+
+      it("keeps auto-approving permissions after SSE send failures", async () => {
+        const appendRawLine = vi.fn();
+        const brokenSseController = {
+          send: vi.fn(() => {
+            throw new Error("stream closed");
+          }),
+          close: vi.fn(),
+        };
+
+        const cloudPermissionServer = server as TestableAgentServer & {
+          emitConsoleLog: (
+            level: "debug" | "info" | "warn" | "error",
+            scope: string,
+            message: string,
+            data?: unknown,
+          ) => void;
+          logger: { debug: (message: string, data?: unknown) => void };
+          session: {
+            payload: typeof TEST_PAYLOAD;
+            sseController: typeof brokenSseController | null;
+            logWriter: {
+              appendRawLine: (runId: string, line: string) => void;
+            };
+          };
+        };
+
+        cloudPermissionServer.session = {
+          payload: TEST_PAYLOAD,
+          sseController: brokenSseController,
+          logWriter: {
+            appendRawLine,
+          },
+        };
+        cloudPermissionServer.logger = {
+          debug: (message: string, data?: unknown) => {
+            cloudPermissionServer.emitConsoleLog(
+              "debug",
+              "agent",
+              message,
+              data,
+            );
+          },
+        };
+
+        const client = cloudPermissionServer.createCloudClient(TEST_PAYLOAD);
+
+        const firstResult = await client.requestPermission({
+          options: ALLOW_OPTIONS,
+          toolCall: { _meta: { codeToolKind: "bash" } },
+        });
+
+        expect(firstResult.outcome.outcome).toBe("selected");
+        expect(brokenSseController.send).toHaveBeenCalledTimes(1);
+        expect(cloudPermissionServer.session.sseController).toBeNull();
+
+        const secondResult = await client.requestPermission({
+          options: ALLOW_OPTIONS,
+          toolCall: { _meta: { codeToolKind: "bash" } },
+        });
+
+        expect(secondResult.outcome.outcome).toBe("selected");
+        expect(brokenSseController.send).toHaveBeenCalledTimes(1);
+        expect(appendRawLine).toHaveBeenCalledTimes(2);
+      });
     });
   });