diff --git a/infra/sandboxes/supervisor/src/index.test.ts b/infra/sandboxes/supervisor/src/index.test.ts
index 8bdb03d..fff3b4e 100644
--- a/infra/sandboxes/supervisor/src/index.test.ts
+++ b/infra/sandboxes/supervisor/src/index.test.ts
@@ -30,6 +30,7 @@ import {
   hasValidBearerToken,
   interactiveScreenCommand,
   isComputerControlUnavailable,
+  isMissingNetworkError,
   nextScreenIndex,
   normalizeWorkspaceRelative,
   parseObservation,
@@ -846,3 +847,17 @@ describe("docker exec stream demux", () => {
     });
   });
 });
+
+describe("isMissingNetworkError", () => {
+  it("recognizes Docker refusing to start a container whose network is gone", () => {
+    expect(
+      isMissingNetworkError(
+        new Error(
+          "(HTTP code 404) no such container - failed to set up container networking: network 065709cd6047a1b2 not found",
+        ),
+      ),
+    ).toBe(true);
+    expect(isMissingNetworkError(new Error("(HTTP code 404) no such container"))).toBe(false);
+    expect(isMissingNetworkError(new Error("image not found"))).toBe(false);
+  });
+});
diff --git a/infra/sandboxes/supervisor/src/index.ts b/infra/sandboxes/supervisor/src/index.ts
index 598efc2..e81e9a7 100644
--- a/infra/sandboxes/supervisor/src/index.ts
+++ b/infra/sandboxes/supervisor/src/index.ts
@@ -71,6 +71,7 @@ import {
   hasValidBearerToken,
   interactiveScreenCommand,
   isComputerControlUnavailable,
+  isMissingNetworkError,
   nextScreenIndex,
   normalizeWorkspaceRelative,
   parseObservation,
@@ -287,12 +288,24 @@ app.post("/computers", async (c) => {
           (!brokerSocketDir || githubBrokerSocketMounted(info.Mounts)) &&
           extraBindsMounted(info.Mounts, resolveExtraBinds())
         ) {
-          if (!info.State.Running) await existing.start();
-          return c.json({
-            id: existing.id,
-            image: COMPUTER_IMAGE,
-            resumed: true,
-          });
+          // A container whose network was removed (a stack restart or network prune)
+          // never starts again; recreate it below on a fresh network with the same home.
+          const running =
+            info.State.Running ||
+            (await existing.start().then(
+              () => true,
+              (error: unknown) => {
+                if (isMissingNetworkError(error)) return false;
+                throw error;
+              },
+            ));
+          if (running) {
+            return c.json({
+              id: existing.id,
+              image: COMPUTER_IMAGE,
+              resumed: true,
+            });
+          }
         }
       }
 
diff --git a/infra/sandboxes/supervisor/src/supervisor-logic.ts b/infra/sandboxes/supervisor/src/supervisor-logic.ts
index 58962b5..fa469e1 100644
--- a/infra/sandboxes/supervisor/src/supervisor-logic.ts
+++ b/infra/sandboxes/supervisor/src/supervisor-logic.ts
@@ -83,6 +83,11 @@ export async function preferComputerControl<T>(
   }
 }
 
+/** Docker cannot start a container whose network was removed underneath it. */
+export function isMissingNetworkError(error: unknown) {
+  return /network \S+ not found/i.test(error instanceof Error ? error.message : String(error));
+}
+
 export class ComputerControlUnavailableError extends Error {
   constructor(message = "computer control unavailable") {
     super(message);