diff --git a/src/orchestrator.start-mount.test.ts b/src/orchestrator.start-mount.test.ts
index b7f6fb1..53c7fbb 100644
--- a/src/orchestrator.start-mount.test.ts
+++ b/src/orchestrator.start-mount.test.ts
@@ -165,6 +165,72 @@ describe("startMount initial-sync idle budget", () => {
     );
   });
 
+  it("classifies a rejected initial-sync launch transport", async () => {
+    // The launch exec is the first long-lived call in startMount. Daytona's
+    // proxy read timeout is ~120s, so a rejection here is exactly what a
+    // wedged mount looks like from the outside — and while this call was
+    // unwrapped, the raw transport error matched none of the message prefixes
+    // callers classify on, so it fell through to their "unknown" bucket and
+    // the real cause was discarded. See AgentWorkforce/sandbox#45.
+    const cause = new Error("read ETIMEDOUT after 120000ms");
+    let calls = 0;
+    const orchestrator = new SandboxOrchestrator<{ id: string }>({
+      provision: async () => ({ id: "sbx" }),
+      uploadBundle: async () => {},
+      runScript: async () => {
+        calls += 1;
+        if (calls === 2) throw cause;
+        return { output: "ok", exitCode: 0 };
+      },
+      teardown: async () => {},
+    });
+
+    await assert.rejects(
+      orchestrator.startMount({ id: "sbx" }, MOUNT),
+      (error: unknown) => {
+        assert.ok(error instanceof Error);
+        assert.match(
+          error.message,
+          /Failed to launch relayfile initial sync: read ETIMEDOUT after 120000ms/u,
+        );
+        assert.equal(error.cause, cause);
+        return true;
+      },
+    );
+    assert.equal(calls, 2);
+  });
+
+  it("classifies a rejected daemon-start transport", async () => {
+    // The other formerly-unwrapped exec. Reached only after the initial sync
+    // reports a clean exit, so it needs the full happy path in front of it.
+    const cause = new Error("read ETIMEDOUT after 120000ms");
+    const orchestrator = new SandboxOrchestrator<{ id: string }>({
+      provision: async () => ({ id: "sbx" }),
+      uploadBundle: async () => {},
+      runScript: async (_handle, options) => {
+        if (options.command.includes("nohup relayfile-mount")) throw cause;
+        if (options.command.includes("relayfile-initial-sync-exit:")) {
+          return { output: "relayfile-initial-sync-exit:0", exitCode: 0 };
+        }
+        return { output: "ok", exitCode: 0 };
+      },
+      teardown: async () => {},
+    });
+
+    await assert.rejects(
+      orchestrator.startMount({ id: "sbx" }, MOUNT),
+      (error: unknown) => {
+        assert.ok(error instanceof Error);
+        assert.match(
+          error.message,
+          /Failed to start relayfile mount: read ETIMEDOUT after 120000ms/u,
+        );
+        assert.equal(error.cause, cause);
+        return true;
+      },
+    );
+  });
+
   it("requests a complete readiness traversal with bounded foreground concurrency", async () => {
     const { orchestrator, commands } = recordingRuntime();
     await orchestrator.startMount({ id: "sbx" }, MOUNT);
diff --git a/src/orchestrator.ts b/src/orchestrator.ts
index 76159a1..28a04ea 100644
--- a/src/orchestrator.ts
+++ b/src/orchestrator.ts
@@ -252,21 +252,30 @@ export class SandboxOrchestrator<Handle> {
     // mount lease, and the exit sentinel is written only after the one-shot
     // supervisor has exited and released that lease.
     const initialSyncRun = { runId: relayfileInitialSyncRunId() };
-    const launch = await this.runtime.runScript(handle, {
-      command: withRelayfileInitialSyncEnvironment(
-        buildRelayfileMountInitialSyncBackgroundShell(
-          {
-            ...config,
-            idleTimeoutSeconds: initialSyncIdleTimeoutSeconds,
-          },
-          initialSyncRun,
+    let launch: SandboxCommandResult;
+    try {
+      launch = await this.runtime.runScript(handle, {
+        command: withRelayfileInitialSyncEnvironment(
+          buildRelayfileMountInitialSyncBackgroundShell(
+            {
+              ...config,
+              idleTimeoutSeconds: initialSyncIdleTimeoutSeconds,
+            },
+            initialSyncRun,
+          ),
+          initialSyncIdleTimeoutSeconds,
+          initialSyncReadConcurrency,
+          initialSyncMaxFilesPerCycle,
         ),
-        initialSyncIdleTimeoutSeconds,
-        initialSyncReadConcurrency,
-        initialSyncMaxFilesPerCycle,
-      ),
-      cwd,
-    });
+        cwd,
+      });
+    } catch (error) {
+      const detail = error instanceof Error ? error.message : String(error);
+      throw new Error(
+        `Failed to launch relayfile initial sync: ${detail}`,
+        { cause: error },
+      );
+    }
     if (launch.exitCode !== 0) {
       throw new Error(`Failed to launch relayfile initial sync: ${launch.output}`);
     }
@@ -338,13 +347,22 @@ export class SandboxOrchestrator<Handle> {
       await sleepMs(pollIntervalMs);
     }
 
-    const start = await this.runtime.runScript(handle, {
-      command: withRelayfileBootstrapIdleTimeout(
-        buildRelayfileMountStartShell(config),
-        initialSyncIdleTimeoutSeconds,
-      ),
-      cwd,
-    });
+    let start: SandboxCommandResult;
+    try {
+      start = await this.runtime.runScript(handle, {
+        command: withRelayfileBootstrapIdleTimeout(
+          buildRelayfileMountStartShell(config),
+          initialSyncIdleTimeoutSeconds,
+        ),
+        cwd,
+      });
+    } catch (error) {
+      const detail = error instanceof Error ? error.message : String(error);
+      throw new Error(
+        `Failed to start relayfile mount: ${detail}`,
+        { cause: error },
+      );
+    }
     if (start.exitCode !== 0) {
       throw new Error(`Failed to start relayfile mount: ${start.output}`);
     }