diff --git a/apps/server/scripts/acp-mock-agent.ts b/apps/server/scripts/acp-mock-agent.ts
index 44011bc7f2d4b..d53d0eaccc2f7 100644
--- a/apps/server/scripts/acp-mock-agent.ts
+++ b/apps/server/scripts/acp-mock-agent.ts
@@ -1,5 +1,6 @@
 #!/usr/bin/env node
 // @effect-diagnostics nodeBuiltinImport:off
+import * as NodeChildProcess from "node:child_process";
 import * as NodeFS from "node:fs";
 
 import * as Effect from "effect/Effect";
@@ -56,6 +57,10 @@ const emitTrackedToolCallKindThenHang = process.env.T3_ACP_EMIT_TRACKED_TOOL_CAL
 const clientFsProbePath = process.env.T3_ACP_CLIENT_FS_PROBE_PATH;
 const clientFsProbeLogPath = process.env.T3_ACP_CLIENT_FS_PROBE_LOG_PATH;
 const encodeJson = Schema.encodeSync(Schema.fromJsonString(Schema.Unknown));
+// "hang" keeps the prompt running after the command starts; "end_turn" answers while it runs.
+const emitRunningCommand = process.env.T3_ACP_EMIT_RUNNING_COMMAND;
+const runningCommandPidPath = process.env.T3_ACP_RUNNING_COMMAND_PID_PATH;
+const agentPidPath = process.env.T3_ACP_AGENT_PID_PATH;
 const emitEmptySuccessfulBash = process.env.T3_ACP_EMIT_EMPTY_SUCCESSFUL_BASH === "1";
 const emitEmptySuccessfulBashThenHang =
   process.env.T3_ACP_EMIT_EMPTY_SUCCESSFUL_BASH_THEN_HANG === "1";
@@ -1351,6 +1356,39 @@ const program = Effect.gen(function* () {
         return yield* AcpError.AcpRequestError.internalError("Mock prompt failure");
       }
 
+      if (emitRunningCommand !== undefined) {
+        // The command is a long-lived Node child so the scenario runs on every platform.
+        const command = NodeChildProcess.spawn(
+          process.execPath,
+          ["-e", "setInterval(() => {}, 1 << 30)"],
+          { stdio: "ignore" },
+        );
+        yield* Effect.callback<void>((resume) => {
+          command.once("spawn", () => resume(Effect.void));
+          command.once("error", (error) => resume(Effect.die(error)));
+        });
+        if (runningCommandPidPath !== undefined) {
+          NodeFS.writeFileSync(runningCommandPidPath, String(command.pid));
+        }
+        if (agentPidPath !== undefined) {
+          NodeFS.writeFileSync(agentPidPath, String(process.pid));
+        }
+        yield* agent.client.sessionUpdate({
+          sessionId: requestedSessionId,
+          update: {
+            sessionUpdate: "tool_call_update",
+            toolCallId: "running-command",
+            title: "run_command",
+            kind: "execute",
+            status: "in_progress",
+            rawInput: { command: "npm run dev" },
+          },
+        });
+        if (emitRunningCommand === "end_turn")
+          return yield* finishPrompt(requestedSessionId, "end_turn");
+        return yield* Effect.never;
+      }
+
       if (emitTrackedToolCallKindThenHang !== undefined) {
         yield* agent.client.sessionUpdate({
           sessionId: requestedSessionId,
diff --git a/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.test.ts b/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.test.ts
index 0945a282cee2c..744c72668a8f7 100644
--- a/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.test.ts
+++ b/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.test.ts
@@ -22,6 +22,7 @@ import * as Exit from "effect/Exit";
 import * as FileSystem from "effect/FileSystem";
 import * as Layer from "effect/Layer";
 import * as Path from "effect/Path";
+import * as Queue from "effect/Queue";
 import * as Stream from "effect/Stream";
 import { ChildProcessSpawner } from "effect/process";
 import type * as EffectAcpSchema from "effect-acp/compat";
@@ -1243,3 +1244,219 @@ describe("AntigravityAdapterV2 session system prompt", () => {
       }).pipe(Effect.provide(layerSession), Effect.scoped),
   );
 });
+
+describe("AntigravityAdapterV2 commands started during a turn", () => {
+  const pidIsRunning = (pid: number) => {
+    try {
+      process.kill(pid, 0);
+      return true;
+    } catch {
+      return false;
+    }
+  };
+
+  const openMockSession = (label: string, runningCommand: "hang" | "end_turn") =>
+    Effect.gen(function* () {
+      const childProcessSpawner = yield* ChildProcessSpawner.ChildProcessSpawner;
+      const fileSystem = yield* FileSystem.FileSystem;
+      const path = yield* Path.Path;
+      const crypto = yield* SecureRandom.SecureRandom;
+      const mockAgentPath = yield* path.fromFileUrl(
+        new URL("../../../scripts/acp-mock-agent.ts", import.meta.url),
+      );
+      const workspace = yield* fileSystem.makeTempDirectoryScoped({ prefix: `t3-ag-${label}-` });
+      const commandPidPath = path.join(workspace, "command.pid");
+      const agentPidPath = path.join(workspace, "agent.pid");
+      const commandPids: Array<number> = [];
+      yield* Effect.addFinalizer(() =>
+        Effect.sync(() => {
+          for (const pid of commandPids) if (pidIsRunning(pid)) process.kill(pid, "SIGKILL");
+        }),
+      );
+      // The mock publishes the PID once the command has spawned, before it reports the command.
+      const readCommandPid = Effect.gen(function* () {
+        const pid = Number(yield* fileSystem.readFileString(commandPidPath));
+        commandPids.push(pid);
+        return pid;
+      });
+      const instanceId = ProviderInstanceId.make(`antigravity-${label}`);
+      const adapter = yield* makeAntigravityAdapterV2({
+        instanceId,
+        selfInvocation: yield* resolveSelfInvocation(),
+        makeRuntime: (input) =>
+          makeAntigravityAcpRuntime({
+            ...input,
+            childProcessSpawner,
+            spawn: {
+              command: process.execPath,
+              args: [mockAgentPath],
+              cwd: input.cwd,
+              env: {
+                T3_ACP_ANTIGRAVITY: "1",
+                T3_ACP_RUNNING_COMMAND_PID_PATH: commandPidPath,
+                T3_ACP_AGENT_PID_PATH: agentPidPath,
+                T3_ACP_EMIT_RUNNING_COMMAND: runningCommand,
+              },
+            },
+          }).pipe(Effect.provideService(SecureRandom.SecureRandom, crypto)),
+        withProcess: (_stop, task) => task,
+        defaultModel: Effect.undefined,
+      });
+      const threadId = ThreadId.make(`thread-antigravity-${label}`);
+      const runtimePolicy = ProviderAdapter.ProviderAdapterV2RuntimePolicy.make({
+        runtimeMode: "full-access",
+        interactionMode: "default",
+        cwd: workspace,
+      });
+      const modelSelection = { instanceId, model: "gemini-test-low" } as const;
+      const session = yield* adapter.openSession({
+        threadId,
+        providerSessionId: ProviderSessionId.make(`provider-session-antigravity-${label}`),
+        modelSelection,
+        runtimePolicy,
+      });
+      const providerThread = yield* session.ensureThread({
+        threadId,
+        modelSelection,
+        runtimePolicy,
+      });
+      const events = yield* Queue.unbounded<ProviderAdapter.ProviderAdapterV2Event>();
+      yield* session.events.pipe(
+        Stream.runForEach((event) => Queue.offer(events, event)),
+        Effect.forkScoped({ startImmediately: true }),
+      );
+      const seen: Array<ProviderAdapter.ProviderAdapterV2Event> = [];
+      const waitFor = (predicate: (event: ProviderAdapter.ProviderAdapterV2Event) => boolean) =>
+        Queue.take(events).pipe(
+          Effect.tap((event) => Effect.sync(() => seen.push(event))),
+          Effect.repeat({ until: predicate }),
+        );
+      const waitForCommand = waitFor(
+        (event) =>
+          event.type === "turn_item.updated" &&
+          event.turnItem.type === "command_execution" &&
+          event.turnItem.nativeItemRef?.nativeId?.includes("running-command") === true,
+      );
+      const waitForTerminal = waitFor((event) => event.type === "turn.terminal").pipe(
+        Effect.map((event) => (event.type === "turn.terminal" ? event.status : undefined)),
+      );
+      const commandItem = (toolCallId: string) => {
+        const command = seen.findLast(
+          (event) =>
+            event.type === "turn_item.updated" &&
+            event.turnItem.type === "command_execution" &&
+            event.turnItem.nativeItemRef?.nativeId?.includes(toolCallId) === true,
+        );
+        return command?.type === "turn_item.updated" ? command.turnItem : undefined;
+      };
+
+      const startTurn = (ordinal: number) =>
+        Effect.gen(function* () {
+          const now = yield* DateTime.now;
+          yield* session.startTurn({
+            appThread: {
+              createdBy: "user",
+              creationSource: "web",
+              id: threadId,
+              projectId: ProjectId.make(`project-antigravity-${label}`),
+              title: `Antigravity ${label}`,
+              providerInstanceId: instanceId,
+              modelSelection,
+              runtimeMode: "full-access",
+              interactionMode: "default",
+              branch: null,
+              worktreePath: workspace,
+              activeProviderThreadId: providerThread.id,
+              lineage: { parentThreadId: null, relationshipToParent: null, rootThreadId: threadId },
+              forkedFrom: null,
+              createdAt: now,
+              updatedAt: now,
+              archivedAt: null,
+              settledOverride: null,
+              settledAt: null,
+              lastVisitedAt: null,
+              deletedAt: null,
+            },
+            threadId,
+            runId: RunId.make(`run-antigravity-${label}-${ordinal}`),
+            runOrdinal: ordinal,
+            providerTurnOrdinal: ordinal,
+            attemptId: RunAttemptId.make(`attempt-antigravity-${label}-${ordinal}`),
+            rootNodeId: NodeId.make(`node-antigravity-${label}-${ordinal}`),
+            providerThread,
+            message: {
+              createdBy: "user",
+              creationSource: "web",
+              messageId: MessageId.make(`message-antigravity-${label}-${ordinal}`),
+              text: "start a long command",
+              attachments: [],
+            },
+            modelSelection,
+            runtimePolicy,
+          });
+        });
+
+      return {
+        session,
+        providerThread,
+        startTurn,
+        waitForCommand,
+        waitForTerminal,
+        readCommandPid,
+        readAgentPid: fileSystem.readFileString(agentPidPath).pipe(Effect.map(Number)),
+        commandItem,
+      };
+    });
+
+  it.effect("keeps a command running past end_turn reachable by Stop", () =>
+    Effect.gen(function* () {
+      const mock = yield* openMockSession("command-outlives-turn", "end_turn");
+      yield* mock.startTurn(1);
+      assert.equal(yield* mock.waitForTerminal, "completed");
+      const commandPid = yield* mock.readCommandPid;
+      assert.isTrue(pidIsRunning(commandPid));
+      const command = mock.commandItem("running-command");
+      assert.equal(command?.status, "running");
+      if (command?.providerTurnId == null) return yield* Effect.die("missing command item");
+
+      yield* mock.session.interruptTurn({
+        providerThread: mock.providerThread,
+        providerTurnId: command.providerTurnId,
+        requestRuntimeRestart: true,
+      });
+      assert.isFalse(pidIsRunning(commandPid), "Stop ends the command");
+    }).pipe(Effect.provide(layerSession), Effect.scoped),
+  );
+
+  it.effect.each(["Stop", "fallback restart"])(
+    "lets %s end the running command and respawns the agent for the next turn",
+    (action) =>
+      Effect.gen(function* () {
+        const mock = yield* openMockSession("command-stopped", "hang");
+        yield* mock.startTurn(1);
+        yield* mock.waitForCommand;
+        const commandPid = yield* mock.readCommandPid;
+        assert.isTrue(pidIsRunning(commandPid));
+        const agentPid = yield* mock.readAgentPid;
+        assert.isTrue(pidIsRunning(agentPid));
+        const providerTurnId = mock.commandItem("running-command")?.providerTurnId;
+        if (providerTurnId == null) return yield* Effect.die("missing command item");
+
+        yield* mock.session.interruptTurn({
+          providerThread: mock.providerThread,
+          providerTurnId,
+          ...(action === "Stop" ? { requestRuntimeRestart: true } : {}),
+        });
+        assert.equal(yield* mock.waitForTerminal, "interrupted");
+        assert.isFalse(pidIsRunning(commandPid), `${action} ends the command`);
+        assert.isFalse(pidIsRunning(agentPid), `${action} ends the ACP agent`);
+
+        yield* mock.startTurn(2);
+        yield* mock.waitForCommand;
+        assert.isTrue(pidIsRunning(yield* mock.readCommandPid), "turn 2 starts a command");
+        const nextAgentPid = yield* mock.readAgentPid;
+        assert.notEqual(nextAgentPid, agentPid, "turn 2 respawns the ACP agent");
+        assert.isTrue(pidIsRunning(nextAgentPid));
+      }).pipe(Effect.provide(layerSession), Effect.scoped),
+  );
+});
diff --git a/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.ts b/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.ts
index 1490140c1e6e2..9d927e168634e 100644
--- a/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.ts
+++ b/apps/server/src/orchestration-v2/Adapters/AntigravityAdapterV2.ts
@@ -6,6 +6,7 @@ import {
   type ProviderSetupError,
 } from "@t3tools/contracts";
 import type { SelfInvocation } from "@t3tools/shared/nodeRuntime";
+import * as HostProcess from "@t3tools/shared/HostProcess";
 import * as SecureRandom from "effect/crypto/SecureRandom";
 import * as Effect from "effect/Effect";
 import * as FileSystem from "effect/FileSystem";
@@ -139,6 +140,7 @@ export function makeAntigravityAcpAdapterFlavor(
   const makeRuntime = Effect.fn("AntigravityAdapterV2.makeRuntime")(
     function* (input: AcpAdapterV2RuntimeInput) {
       const scope = yield* Scope.fork(yield* Effect.scope);
+      const platform = yield* HostProcess.Platform;
       const runtime = yield* options
         .withProcess(
           Scope.close(scope, Exit.void),
@@ -146,6 +148,9 @@ export function makeAntigravityAcpAdapterFlavor(
             ...input,
             clientFileReads: true,
             sessionSystemPromptAppend: PULL_REQUEST_LINKING_INSTRUCTIONS,
+            ownDetachedProcessGroup: true,
+            ownDescendantProcessGroups: platform === "linux",
+            processGroupPlatform: platform,
             additionalDirectories: [options.host.paths.attachmentsDir],
           }),
         )
@@ -233,6 +238,14 @@ export function makeAntigravityAcpAdapterFlavor(
       ),
     // Loading history replays tool calls; resume avoids replay.
     subagentsIdleOnTurnCompletion: true,
+    restartRuntimeOnEveryInterrupt: true,
+    terminateRuntimeProcessGroupOnInterrupt: true,
+    // A started command can outlive end_turn. Its item stays running after the turn
+    // completes so Stop can still reach it; the turn itself does not wait for it.
+    extractBackgroundTaskId: (toolCall) =>
+      toolCall.kind === "execute" && toolCall.status !== undefined && toolCall.status !== "pending"
+        ? toolCall.toolCallId
+        : undefined,
     ...(options.onSessionEvent === undefined ? {} : { onSessionEvent: options.onSessionEvent }),
     applyModelSelection: Effect.fn("AntigravityAdapterV2.applyModelSelection")(function* ({
       runtime,