fix(client): reject oversized relay messages without disconnecting

Check the encrypted wire size synchronously before submission, so a frame below the direct limit cannot close the relay and leave workspace creation resubmitting forever. Keep the relay limit shared with the existing checkout diff budget.

packages/client/src/daemon-client-relay-e2ee-transport.ts

@@ -1,3 +1,4 @@
+import { MAX_RELAY_WEBSOCKET_MESSAGE_BYTES } from "@getpaseo/protocol/websocket-message-limit";
 import {
   createClientChannel,
   type EncryptedChannel,
@@ -8,7 +9,11 @@ import type {
   DaemonTransportFactory,
   TransportLogger,
 } from "./daemon-client-transport-types.js";
-import { extractRelayMessage, normalizeTransportPayload } from "./daemon-client-transport-utils.js";
+import {
+  extractRelayMessage,
+  normalizeTransportPayload,
+  messageTooLargeError,
+} from "./daemon-client-transport-utils.js";
 
 type OpenHandler = () => void;
 type CloseHandler = (event?: unknown) => void;
@@ -137,7 +142,13 @@ export function createEncryptedTransport(
       if (!channel) {
         throw new Error("Encrypted channel not ready");
       }
-      void channel.send(normalizeTransportPayload(data)).catch((error) => {
+      const payload = normalizeTransportPayload(data);
+      // Reject synchronously so the requesting operation fails without closing the transport.
+      const wireBytes = channel.outboundWireByteLength(payload);
+      if (wireBytes > MAX_RELAY_WEBSOCKET_MESSAGE_BYTES) {
+        throw messageTooLargeError(wireBytes, MAX_RELAY_WEBSOCKET_MESSAGE_BYTES);
+      }
+      void channel.send(payload).catch((error) => {
         emitError(error);
       });
     },

packages/client/src/daemon-client-transport-utils.ts

@@ -133,3 +133,10 @@ export function encodeUtf8String(value: string): Uint8Array {
   }
   return out;
 }
+
+export function messageTooLargeError(size: number, limit: number): Error {
+  const toMiB = (bytes: number) => (bytes / (1024 * 1024)).toFixed(1);
+  return new Error(
+    `Message is too large to send (${toMiB(size)} MiB). The limit is ${toMiB(limit)} MiB, so send fewer or smaller attachments.`,
+  );
+}

packages/client/src/daemon-client.ts

@@ -1,3 +1,4 @@
+import { messageTooLargeError } from "./daemon-client-transport-utils.js";
 import { legacyUsageIcon } from "./legacy-usage-icons.js";
 import { subscribeTimeline, type TimelineMessage } from "./timeline-subscription/index.js";
 import { ProviderSnapshotUpdates } from "./provider-snapshots/index.js";
@@ -1136,20 +1137,14 @@ function getTransportFrameSize(frame: string | Uint8Array | ArrayBuffer): number
 function assertTransportFrameFits(frame: string | Uint8Array | ArrayBuffer): void {
   if (typeof frame !== "string") {
     if (frame.byteLength > MAX_WEBSOCKET_MESSAGE_BYTES)
-      throw messageTooLargeError(frame.byteLength);
+      throw messageTooLargeError(frame.byteLength, MAX_WEBSOCKET_MESSAGE_BYTES);
     return;
   }
   // UTF-8 needs at most three bytes per UTF-16 unit, so only a string near the limit is measured.
   if (frame.length * 3 <= MAX_WEBSOCKET_MESSAGE_BYTES) return;
   const size = new TextEncoder().encode(frame).byteLength;
-  if (size > MAX_WEBSOCKET_MESSAGE_BYTES) throw messageTooLargeError(size);
-}
-
-function messageTooLargeError(size: number): Error {
-  const toMiB = (bytes: number) => (bytes / (1024 * 1024)).toFixed(1);
-  return new Error(
-    `Message is too large to send (${toMiB(size)} MiB). The limit is ${toMiB(MAX_WEBSOCKET_MESSAGE_BYTES)} MiB, so send fewer or smaller attachments.`,
-  );
+  if (size > MAX_WEBSOCKET_MESSAGE_BYTES)
+    throw messageTooLargeError(size, MAX_WEBSOCKET_MESSAGE_BYTES);
 }
 
 function describeInboundTransportFrame(

packages/protocol/src/websocket-message-limit.ts

@@ -1,2 +1,5 @@
 /** Largest WebSocket message the daemon accepts. A bigger one closes the connection with 1009. */
 export const MAX_WEBSOCKET_MESSAGE_BYTES = 100 * 1024 * 1024;
+
+/** Largest encrypted frame the relay accepts. */
+export const MAX_RELAY_WEBSOCKET_MESSAGE_BYTES = 32 * 1024 * 1024;

packages/server/package.json

@@ -89,7 +89,7 @@
     "speech:transcribe:local": "tsx scripts/transcribe-local-wav.ts",
     "test": "npm run test:unit && npm run test:integration",
     "test:unit": "vitest run --fileParallelism --exclude \"**/*.e2e.test.ts\"",
-    "test:integration": "vitest run --maxWorkers=1 src/server/daemon-e2e/filesystem.e2e.test.ts src/server/daemon-e2e/file-download.e2e.test.ts src/server/daemon-e2e/cli-logs-follow.e2e.test.ts src/server/creation/creation.e2e.test.ts src/server/daemon-e2e/terminal-workspace-sdk.e2e.test.ts src/server/daemon-e2e/models.e2e.test.ts src/server/daemon-e2e/live-preferences.e2e.test.ts src/server/daemon-e2e/oversized-message.e2e.test.ts src/server/agent/model-catalog.e2e.test.ts src/server/plugins/plugin-paseo-api.e2e.test.ts && vitest run --maxWorkers=1 src/server/daemon-e2e/git-operations.e2e.test.ts -t \"merges into\" && vitest run --maxWorkers=1 src/server/session.create-agent-worktree-autoarchive.e2e.test.ts -t \"creates a worktree and auto-archives both\" && vitest run --maxWorkers=1 src/server/agent/providers/opencode-bridge.local.e2e.test.ts -t \"versioned runtime\"",
+    "test:integration": "vitest run --maxWorkers=1 src/server/daemon-e2e/filesystem.e2e.test.ts src/server/daemon-e2e/file-download.e2e.test.ts src/server/daemon-e2e/cli-logs-follow.e2e.test.ts src/server/creation/creation.e2e.test.ts src/server/daemon-e2e/terminal-workspace-sdk.e2e.test.ts src/server/daemon-e2e/models.e2e.test.ts src/server/daemon-e2e/live-preferences.e2e.test.ts src/server/daemon-e2e/oversized-message.e2e.test.ts src/server/agent/model-catalog.e2e.test.ts src/server/plugins/plugin-paseo-api.e2e.test.ts && vitest run --maxWorkers=1 src/server/daemon-e2e/git-operations.e2e.test.ts -t \"merges into\" && vitest run --maxWorkers=1 src/server/session.create-agent-worktree-autoarchive.e2e.test.ts -t \"creates a worktree and auto-archives both\" && vitest run --maxWorkers=1 src/server/agent/providers/opencode-bridge.local.e2e.test.ts -t \"versioned runtime\" && vitest run --maxWorkers=1 src/server/daemon-e2e/relay-transport.e2e.test.ts -t \"oversized attachments\"",
     "test:hub-cli-contract": "vitest run --maxWorkers=1 src/server/hub/hub-cli-contract.test.ts",
     "test:integration:all": "npm run test:e2e",
     "test:integration:real": "vitest run real.e2e.test.ts",

packages/server/src/server/daemon-e2e/relay-transport.e2e.test.ts

@@ -1,4 +1,6 @@
 import { describe, expect, test } from "vitest";
+import { withTimeout } from "../../utils/promise-timeout.js";
+import { DaemonClient } from "../test-utils/daemon-client.js";
 import { WebSocket } from "ws";
 import pino from "pino";
 import { Writable } from "node:stream";
@@ -202,12 +204,20 @@ async function waitForCapturedLog(
     if (options.useLocalRelay) {
       relayArgs.push("--var", "PASEO_RELAY_UPSTREAM:");
     }
-    relayProcess = spawn("npx", relayArgs, {
-      cwd: relayDir,
-      env: { ...process.env },
-      stdio: ["ignore", "pipe", "pipe"],
-      detached: false,
-    });
+    relayProcess = spawn(
+      process.execPath,
+      [
+        "--experimental-vm-modules",
+        path.resolve(relayDir, "../../node_modules/wrangler/wrangler-dist/cli.js"),
+        ...relayArgs.slice(1),
+      ],
+      {
+        cwd: relayDir,
+        env: { ...process.env },
+        stdio: ["ignore", "pipe", "pipe"],
+        detached: false,
+      },
+    );
 
     relayProcess.stdout?.on("data", (data: Buffer) => {
       const lines = data
@@ -241,6 +251,73 @@ async function waitForCapturedLog(
     relayProcess = null;
   };
 
+  test("oversized attachments fail without disconnecting or resubmitting over the relay", async () => {
+    await startRelay({ useLocalRelay: true });
+    const daemon = await createTestPaseoDaemon({
+      relayEnabled: true,
+      relayEndpoint: `127.0.0.1:${relayPort}`,
+      relayUseTls: false,
+      relayPublicUseTls: false,
+    });
+    let client: DaemonClient | null = null;
+    try {
+      const offerUrl = await getPairingOfferUrl({
+        paseoHome: daemon.paseoHome,
+        relayEnabled: true,
+        relayEndpoint: daemon.config.relayEndpoint,
+      });
+      const { serverId, daemonPublicKeyB64 } = decodeOfferFromFragmentUrl(offerUrl);
+      client = new DaemonClient({
+        url: buildRelayWebSocketUrl({
+          endpoint: `127.0.0.1:${relayPort}`,
+          useTls: false,
+          serverId,
+          role: "client",
+        }),
+        e2ee: { enabled: true, daemonPublicKeyB64 },
+        reconnect: { baseDelayMs: 100, maxDelayMs: 100 },
+      });
+      await client.connect();
+      const statuses: string[] = [];
+      client.subscribeConnectionStatus((state) => statuses.push(state.status));
+      for (const imageMiB of [30, 61]) {
+        // Attachments are base64 in the JSON, then E2EE base64 expands the frame again.
+        const images = [
+          { data: "A".repeat(4 * Math.ceil((imageMiB * 1024 * 1024) / 3)), mimeType: "image/png" },
+        ];
+        await expect(
+          withTimeout(
+            client.createWorkspace({
+              source: { kind: "directory", path: daemon.staticDir },
+              agent: {
+                provider: "claude",
+                cwd: daemon.staticDir,
+                initialPrompt: "Describe these screens.",
+                images,
+              },
+            }),
+            10000,
+            "Workspace creation did not settle",
+          ),
+        ).rejects.toThrow(/too large.*32\.0 MiB/);
+        expect((await client.fetchAgents()).entries).toEqual([]);
+      }
+      const agent = await client.createAgent({ provider: "claude", cwd: daemon.staticDir });
+      await expect(
+        client.sendMessage(agent.id, "Describe these screens.", {
+          images: [{ data: "A".repeat(40 * 1024 * 1024), mimeType: "image/png" }],
+        }),
+      ).rejects.toThrow(/too large.*32\.0 MiB/);
+      await client.sendMessage(agent.id, "A small follow-up still works.");
+      expect((await client.fetchAgents()).entries).toHaveLength(1);
+      expect(statuses).toEqual(["connected"]);
+    } finally {
+      await client?.close();
+      await daemon.close();
+      await stopRelay();
+    }
+  }, 60000);
+
   test("daemon connects to relay and client ping/pong works through relay", async () => {
     process.env.PASEO_PRIMARY_LAN_IP = "192.168.1.12";
 

packages/server/src/utils/checkout-git.ts

@@ -1,3 +1,4 @@
+import { MAX_RELAY_WEBSOCKET_MESSAGE_BYTES } from "@getpaseo/protocol/websocket-message-limit";
 import { resolve, dirname, basename } from "path";
 import { existsSync, realpathSync } from "fs";
 import { open as openFile, readFile, stat as statFile } from "fs/promises";
@@ -2152,13 +2153,13 @@ export async function getCheckoutSnapshotFacts(
 
 const PER_FILE_DIFF_MAX_BYTES = 1024 * 1024; // 1MB
 const TOTAL_DIFF_MAX_BYTES = 2 * 1024 * 1024; // 2MB
-const RELAY_MAX_FRAME_BYTES = 32 * 1024 * 1024;
 const CHECKOUT_DIFF_FRAME_HEADROOM_BYTES = 1024 * 1024;
 // Temporary until diffs load lazily per file. The Paseo relay's 32 MiB frame limit is
 // binding: string frames are encrypted and base64-encoded. Reserve 1 MiB plaintext for
 // the surrounding WebSocket JSON envelope after inverting that exact wire expansion.
 export const CHECKOUT_DIFF_MAX_STRUCTURED_BYTES =
-  maxBase64EncryptedPlaintextByteLength(RELAY_MAX_FRAME_BYTES) - CHECKOUT_DIFF_FRAME_HEADROOM_BYTES;
+  maxBase64EncryptedPlaintextByteLength(MAX_RELAY_WEBSOCKET_MESSAGE_BYTES) -
+  CHECKOUT_DIFF_FRAME_HEADROOM_BYTES;
 
 interface StructuredDiffAccumulator {
   files: ParsedDiffFile[];