From 542ba4f9a491e26d4546656e4ba81eb46de2e23e Mon Sep 17 00:00:00 2001
From: Brad Groux <3053586+BradGroux@users.noreply.github.com>
Date: Sun, 30 Aug 2026 07:19:29 -0500
Subject: [PATCH] fix: contain ACP teardown write failures

---
 .../src/__tests__/acp-json-rpc-peer.test.ts   | 36 +++++++++++++++++++
 shared/src/utils/acp-json-rpc-peer.ts         | 20 ++++++-----
 2 files changed, 48 insertions(+), 8 deletions(-)
 create mode 100644 server/src/__tests__/acp-json-rpc-peer.test.ts

diff --git a/server/src/__tests__/acp-json-rpc-peer.test.ts b/server/src/__tests__/acp-json-rpc-peer.test.ts
new file mode 100644
index 00000000..11c4cee7
--- /dev/null
+++ b/server/src/__tests__/acp-json-rpc-peer.test.ts
@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest';
+import { AcpJsonRpcPeer } from '@veritas-kanban/shared';
+
+describe('ACP JSON-RPC peer writes', () => {
+  it('contains transport teardown failures for detached request replies', async () => {
+    const unhandled: unknown[] = [];
+    const onUnhandled = (reason: unknown) => unhandled.push(reason);
+    process.on('unhandledRejection', onUnhandled);
+
+    try {
+      const peer = new AcpJsonRpcPeer({
+        write: async () => {
+          throw new Error('stream destroyed');
+        },
+        onRequest: async () => ({}),
+      });
+
+      peer.acceptChunk('{"jsonrpc":"2.0","id":1,"method":"session/request_permission"}\n');
+      await new Promise<void>((resolve) => setImmediate(resolve));
+
+      expect(unhandled).toEqual([]);
+    } finally {
+      process.off('unhandledRejection', onUnhandled);
+    }
+  });
+
+  it('keeps caller-awaited write failures observable', async () => {
+    const peer = new AcpJsonRpcPeer({
+      write: async () => {
+        throw new Error('stream destroyed');
+      },
+    });
+
+    await expect(peer.notify('session/cancel', {})).rejects.toThrow('stream destroyed');
+  });
+});
diff --git a/shared/src/utils/acp-json-rpc-peer.ts b/shared/src/utils/acp-json-rpc-peer.ts
index 509dd55f..30c6270d 100644
--- a/shared/src/utils/acp-json-rpc-peer.ts
+++ b/shared/src/utils/acp-json-rpc-peer.ts
@@ -76,7 +76,7 @@ export class AcpJsonRpcPeer {
       try {
         record = JSON.parse(line);
       } catch {
-        void this.send(jsonRpcError(null, -32700, 'Parse error'));
+        this.sendDetached(jsonRpcError(null, -32700, 'Parse error'));
         continue;
       }
       this.acceptRecord(record);
@@ -117,7 +117,7 @@ export class AcpJsonRpcPeer {
     }
 
     if (typeof value.method !== 'string' || !value.method.trim()) {
-      if (id !== undefined) void this.send(jsonRpcError(id, -32600, 'Invalid Request'));
+      if (id !== undefined) this.sendDetached(jsonRpcError(id, -32600, 'Invalid Request'));
       return;
     }
     if (id === undefined) {
@@ -127,14 +127,18 @@ export class AcpJsonRpcPeer {
       return;
     }
     if (!this.options.onRequest) {
-      void this.send(jsonRpcError(id, -32601, 'Method not found'));
+      this.sendDetached(jsonRpcError(id, -32601, 'Method not found'));
       return;
     }
-    void Promise.resolve(this.options.onRequest(value.method, value.params, id))
-      .then((result) => this.send({ jsonrpc: '2.0', id, result: result ?? {} }))
-      .catch((error) =>
-        this.send(jsonRpcError(id, -32603, boundedMessage(error, 'Internal error')))
-      );
+    void Promise.resolve(this.options.onRequest(value.method, value.params, id)).then(
+      (result) => this.sendDetached({ jsonrpc: '2.0', id, result: result ?? {} }),
+      (error) =>
+        this.sendDetached(jsonRpcError(id, -32603, boundedMessage(error, 'Internal error')))
+    );
+  }
+
+  private sendDetached(record: AcpJsonRpcMessage): void {
+    void this.send(record).catch(() => undefined);
   }
 
   private send(record: AcpJsonRpcMessage): Promise<void> {