diff --git a/packages/adapter-utils/src/acpx-engine/startup-timing.test.ts b/packages/adapter-utils/src/acpx-engine/startup-timing.test.ts
index 91255745d8..fa07faff41 100644
--- a/packages/adapter-utils/src/acpx-engine/startup-timing.test.ts
+++ b/packages/adapter-utils/src/acpx-engine/startup-timing.test.ts
@@ -7,6 +7,7 @@ import {
   getActiveStepContext,
   measureStartupStep,
   normalizeProviderFamily,
+  runWithoutActiveStep,
   SANDBOX_STARTUP_SPAN_ATTR_PREFIX,
   SANDBOX_STARTUP_SPAN_ATTRS,
   setSandboxRootSpanAttributes,
@@ -495,6 +496,86 @@ describe("getActiveStepContext", () => {
     }, { criticalPath: false });
     expect(seen!.criticalPath).toBe(false);
   });
+
+  it("keeps the ended step store in a timer scheduled inside the step body", async () => {
+    // Node snapshots the active store on each async resource at creation time.
+    // A timer scheduled inside a measured step body keeps that step store, even
+    // after the step span ends. A later run-time exec then reads the ended step
+    // and parents its `sandbox.exec` span to a dead startup step. This test locks
+    // that leak, so the fix and its guard test stay honest.
+    let storeInTimer: ReturnType<typeof getActiveStepContext> = null;
+    let fireTimer!: () => void;
+    const timerRan = new Promise<void>((resolve) => {
+      fireTimer = resolve;
+    });
+
+    await measureStartupStep(
+      { onEvent: vi.fn(async () => {}) },
+      () => 0,
+      "bridge.process-session",
+      async () => {
+        setTimeout(() => {
+          storeInTimer = getActiveStepContext();
+          fireTimer();
+        }, 0);
+        return "started";
+      },
+      { criticalPath: false },
+    );
+
+    // The step span already ended, so the main line reads no active step.
+    expect(getActiveStepContext()).toBeNull();
+
+    await timerRan;
+
+    // Yet the timer callback still reads the ended step context. This is the
+    // store leak the bridge boundary fix removes.
+    expect(storeInTimer).not.toBeNull();
+    expect(storeInTimer!.criticalPath).toBe(false);
+  });
+
+  it("clears the active step for a continuation wrapped in runWithoutActiveStep", async () => {
+    // The bridge boundary wraps its long-lived poll timer in `runWithoutActiveStep`.
+    // A timer scheduled inside that empty store scope reads no active step, so a
+    // later run-time exec opens an unparented span instead of one under the ended
+    // startup step.
+    let storeInTimer: ReturnType<typeof getActiveStepContext> = null;
+    let sawTimer = false;
+    let fireTimer!: () => void;
+    const timerRan = new Promise<void>((resolve) => {
+      fireTimer = resolve;
+    });
+
+    await measureStartupStep(
+      { onEvent: vi.fn(async () => {}) },
+      () => 0,
+      "bridge.process-session",
+      async () => {
+        runWithoutActiveStep(() => {
+          setTimeout(() => {
+            storeInTimer = getActiveStepContext();
+            sawTimer = true;
+            fireTimer();
+          }, 0);
+        });
+        return "started";
+      },
+      { criticalPath: false },
+    );
+
+    await timerRan;
+
+    expect(sawTimer).toBe(true);
+    expect(storeInTimer).toBeNull();
+  });
+
+  it("returns the work result and restores the previous active step", async () => {
+    // Outside any measured step the previous store is empty, so the helper both
+    // returns the work value and leaves the store empty afterward.
+    const value = runWithoutActiveStep(() => "value");
+    expect(value).toBe("value");
+    expect(getActiveStepContext()).toBeNull();
+  });
 });
 
 describe("clampSpanLabel", () => {
diff --git a/packages/adapter-utils/src/acpx-engine/startup-timing.ts b/packages/adapter-utils/src/acpx-engine/startup-timing.ts
index 1de2ceeb88..d13ba73659 100644
--- a/packages/adapter-utils/src/acpx-engine/startup-timing.ts
+++ b/packages/adapter-utils/src/acpx-engine/startup-timing.ts
@@ -332,7 +332,7 @@ export interface ActiveStepContext {
  * a module-level singleton, so the value propagates across `await` boundaries
  * and across package boundaries that share this module.
  */
-const activeStepContextStorage = new AsyncLocalStorage<ActiveStepContext>();
+const activeStepContextStorage = new AsyncLocalStorage<ActiveStepContext | undefined>();
 
 /**
  * Return the active step context, or `null` when no measured step is running.
@@ -344,6 +344,26 @@ export function getActiveStepContext(): ActiveStepContext | null {
   return activeStepContextStorage.getStore() ?? null;
 }
 
+/**
+ * Run `work` with no active step context, then restore the previous store. A
+ * bridge boundary uses this to start its long-lived poll timer and socket
+ * handlers outside the measured step store.
+ *
+ * Node snapshots the active store on each async resource at creation time. So a
+ * timer or a handler scheduled inside a measured step body keeps that step store
+ * after the step span ends. A later run-time exec then reads the ended step and
+ * parents its `sandbox.exec` span to a dead startup step, and it copies the
+ * step's `criticalPath` flag. This helper resets the store for the wrapped work,
+ * so each continuation reads an empty store. Each run-time exec then opens an
+ * unparented span with no stale `criticalPath` flag.
+ *
+ * The helper forwards only the opaque store, so this package stays free of
+ * `@opentelemetry/api`. It needs no Node version gate.
+ */
+export function runWithoutActiveStep<T>(work: () => T): T {
+  return activeStepContextStorage.run(undefined, work);
+}
+
 /**
  * Set a numeric span attribute only when the value is a finite number. A reader
  * that returns `undefined` (the counter is unavailable) yields no attribute,
diff --git a/packages/adapter-utils/src/execution-target.ts b/packages/adapter-utils/src/execution-target.ts
index d1d878d7c2..2ee9c0f049 100644
--- a/packages/adapter-utils/src/execution-target.ts
+++ b/packages/adapter-utils/src/execution-target.ts
@@ -46,6 +46,7 @@ import {
 } from "./server-utils.js";
 import { sanitizeRemoteExecutionEnv } from "./remote-execution-env.js";
 import { preferredShellForSandbox, shellCommandArgs } from "./sandbox-shell.js";
+import { runWithoutActiveStep } from "./acpx-engine/startup-timing.js";
 import type { RuntimeProgressSink, RuntimeStatusSink } from "./runtime-progress.js";
 import type { LocalProcessSandboxOptions } from "./local-process-sandbox.js";
 
@@ -1488,7 +1489,10 @@ export async function startAdapterExecutionTargetProcessSessionBridge(input: {
   };
 
   const liveSockets = new Set<net.Socket>();
-  const server = net.createServer((nextSocket) => {
+  // Register the per-connection socket handlers outside the measured bridge step
+  // store. A stdin write from a socket handler is a run-time exec, not startup
+  // work, so its `sandbox.exec` span must not parent to the ended bridge step.
+  const server = net.createServer((nextSocket) => runWithoutActiveStep(() => {
     liveSockets.add(nextSocket);
     nextSocket.setEncoding("utf8");
     nextSocket.on("error", () => undefined);
@@ -1547,7 +1551,7 @@ export async function startAdapterExecutionTargetProcessSessionBridge(input: {
         });
       }
     });
-  });
+  }));
 
   const poll = async () => {
     if (stopping) return;
@@ -1572,16 +1576,24 @@ export async function startAdapterExecutionTargetProcessSessionBridge(input: {
       return;
     } finally {
       if (!stopping) {
-        pollTimer = setTimeout(() => void poll(), 100);
-        pollTimer.unref?.();
+        schedulePoll();
       }
     }
   };
 
+  // Schedule the long-lived poll timer outside the measured bridge step store.
+  // The poll loop reads remote event files with run-time execs, not startup
+  // work, so a poll `sandbox.exec` span must not parent to the ended bridge step.
+  // `runWithoutActiveStep` also empties the store for the re-arm timer that the
+  // poll body schedules, so every later tick stays unparented too.
+  const schedulePoll = () => {
+    pollTimer = setTimeout(() => runWithoutActiveStep(() => void poll()), 100);
+    pollTimer.unref?.();
+  };
+
   const port = await waitForLocalServerListen(server);
   const agentCommand = await writeProcessSessionProxyScript(proxyDir, port, token);
-  pollTimer = setTimeout(() => void poll(), 100);
-  pollTimer.unref?.();
+  schedulePoll();
 
   return {
     agentCommand,
@@ -1787,6 +1799,11 @@ export async function startAdapterExecutionTargetPaperclipBridge(input: {
     // this flag is enabled. Only intended for active debugging in trusted
     // environments.
     const bridgeDebugEnabled = isBridgeDebugEnabled(process.env);
+    // `startSandboxCallbackBridgeWorker` keeps its awaited queue-directory
+    // setup on the active `bridge.paperclip` step, and resets the store only
+    // for its long-lived poll loop (see `runWithoutActiveStep` inside that
+    // function). So the startup `mkdir` execs stay parented and every later
+    // loop `sandbox.exec` span stays unparented with no stale `criticalPath`.
     worker = await startSandboxCallbackBridgeWorker({
       client,
       queueDir,
diff --git a/packages/adapter-utils/src/sandbox-callback-bridge.test.ts b/packages/adapter-utils/src/sandbox-callback-bridge.test.ts
index 73fc3b472a..f36f63bbef 100644
--- a/packages/adapter-utils/src/sandbox-callback-bridge.test.ts
+++ b/packages/adapter-utils/src/sandbox-callback-bridge.test.ts
@@ -5,6 +5,7 @@ import path from "node:path";
 import { promisify } from "node:util";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
+import { getActiveStepContext, measureStartupStep } from "./acpx-engine/startup-timing.js";
 import { prepareCommandManagedRuntime } from "./command-managed-runtime.js";
 import {
   authorizeSandboxCallbackBridgeRequestWithRoutes,
@@ -471,6 +472,73 @@ describe("sandbox callback bridge", () => {
     }
   });
 
+  it("keeps the queue-directory setup on the startup step but resets the poll loop store", async () => {
+    // The worker starts inside the measured `bridge.paperclip` step. Its awaited
+    // queue-directory setup is startup work, so a `makeDir` `sandbox.exec` span
+    // must keep the active step and its `criticalPath` flag. The long-lived poll
+    // loop runs run-time execs for the whole run, so a loop `sandbox.exec` span
+    // must open unparented with no stale flag. This test reads the active step in
+    // both places and proves the boundary sits at the loop, not the whole worker.
+    let setupStep: ReturnType<typeof getActiveStepContext> | "unset" = "unset";
+    let loopStep: ReturnType<typeof getActiveStepContext> | "unset" = "unset";
+    let resolveFirstPoll: () => void = () => {};
+    const firstPoll = new Promise<void>((resolve) => {
+      resolveFirstPoll = resolve;
+    });
+
+    const rootDir = await mkdtemp(path.join(os.tmpdir(), "paperclip-bridge-step-store-"));
+    cleanupDirs.push(rootDir);
+    const queueDir = path.posix.join(rootDir, "queue");
+
+    const worker = await measureStartupStep(
+      {},
+      () => 0,
+      "bridge.paperclip",
+      () =>
+        startSandboxCallbackBridgeWorker({
+          client: {
+            makeDir: async () => {
+              setupStep = getActiveStepContext();
+            },
+            makeDirs: async () => {
+              setupStep = getActiveStepContext();
+            },
+            listJsonFiles: async () => {
+              loopStep = getActiveStepContext();
+              resolveFirstPoll();
+              return [];
+            },
+            readTextFile: async () => {
+              throw new Error("unexpected readTextFile");
+            },
+            writeTextFile: async () => {
+              throw new Error("unexpected writeTextFile");
+            },
+            rename: async () => {
+              throw new Error("unexpected rename");
+            },
+            remove: async () => {},
+          },
+          queueDir,
+          authorizeRequest: async () => null,
+          handleRequest: async () => ({ status: 200, body: "ok" }),
+        }),
+      { criticalPath: false },
+    );
+
+    await firstPoll;
+    await worker.stop();
+
+    // The setup ran on the active step, so its exec span parents to the step.
+    expect(setupStep).not.toBe("unset");
+    expect(setupStep).not.toBeNull();
+    expect((setupStep as { criticalPath?: boolean }).criticalPath).toBe(false);
+
+    // The loop ran outside that store, so its exec span opens unparented with no
+    // stale `criticalPath` flag.
+    expect(loopStep).toBeNull();
+  });
+
   it("serializes remote response writes so stop does not recreate a late orphaned response", async () => {
     const rootDir = await mkdtemp(path.join(os.tmpdir(), "paperclip-bridge-response-lock-"));
     cleanupDirs.push(rootDir);
diff --git a/packages/adapter-utils/src/sandbox-callback-bridge.ts b/packages/adapter-utils/src/sandbox-callback-bridge.ts
index d990adbef3..b21d8a1874 100644
--- a/packages/adapter-utils/src/sandbox-callback-bridge.ts
+++ b/packages/adapter-utils/src/sandbox-callback-bridge.ts
@@ -3,6 +3,7 @@ import { promises as fs } from "node:fs";
 import os from "node:os";
 import path from "node:path";
 
+import { runWithoutActiveStep } from "./acpx-engine/startup-timing.js";
 import type { CommandManagedRuntimeRunner } from "./command-managed-runtime.js";
 import { preferredShellForSandbox, shellCommandArgs } from "./sandbox-shell.js";
 import type { RunProcessResult } from "./server-utils.js";
@@ -745,7 +746,13 @@ export async function startSandboxCallbackBridgeWorker(input: {
     }
   };
 
-  const loop = (async () => {
+  // Start the long-lived poll loop outside the measured startup-step store.
+  // The `makeDir` calls above are startup work and must keep the active
+  // `bridge.paperclip` step. The loop runs run-time execs for the whole run,
+  // so each loop `sandbox.exec` span must not parent to the ended step or copy
+  // its `criticalPath` flag. `runWithoutActiveStep` empties the store for the
+  // loop only; Node keeps the empty store on every later poll continuation.
+  const loop = runWithoutActiveStep(() => (async () => {
     try {
       while (true) {
         const fileNames = await input.client.listJsonFiles(directories.requestsDir);
@@ -785,7 +792,7 @@ export async function startSandboxCallbackBridgeWorker(input: {
         settleResolve();
       }
     }
-  })();
+  })());
 
   void loop;
 
diff --git a/server/src/__tests__/environment-execution-target.test.ts b/server/src/__tests__/environment-execution-target.test.ts
index e59e6022e7..c49557dc71 100644
--- a/server/src/__tests__/environment-execution-target.test.ts
+++ b/server/src/__tests__/environment-execution-target.test.ts
@@ -10,6 +10,7 @@ vi.mock("../services/environment-config.js", () => ({
 
 import {
   measureStartupStep,
+  runWithoutActiveStep,
   SANDBOX_STARTUP_SPAN_ATTRS,
 } from "@paperclipai/adapter-utils/acpx-engine/startup-timing";
 import {
@@ -847,4 +848,116 @@ describe("resolveEnvironmentExecutionTarget", () => {
     // The seam reached the log callback exactly once (the stdout delivery).
     expect(onLog).toHaveBeenCalledTimes(1);
   });
+
+  // Fire one run-time exec from a bridge continuation that runs after the step
+  // span ended. Each bridge step (`bridge.paperclip`, `bridge.process-session`)
+  // starts long-lived work with `criticalPath: false`. The bridge boundary wraps
+  // that long-lived work in `runWithoutActiveStep`, exactly as modeled here, so
+  // the continuation reads an empty active step. Return the recorded exec span.
+  async function runContinuationExec(step: string, options: { wrap: boolean }) {
+    const { tracer, contextWithSpan, spans } = createRecordingTrace();
+    const runner = await runnerFor({
+      provider: "daytona",
+      execResult: { exitCode: 0, signal: null, timedOut: false, stdout: "", stderr: "" },
+      tracer,
+    });
+
+    let resolveExec!: () => void;
+    const execDone = new Promise<void>((resolve) => {
+      resolveExec = resolve;
+    });
+
+    // Schedule the exec from a timer inside the step body, so it fires after the
+    // step span ends. The `wrap` flag models the fix: when true, the boundary
+    // wraps the long-lived work in `runWithoutActiveStep`; when false, it models
+    // the pre-fix leak.
+    const scheduleContinuation = () => {
+      setTimeout(() => {
+        void runner.execute({ command: "echo" }).then(() => resolveExec());
+      }, 0);
+    };
+
+    await measureStartupStep(
+      {},
+      () => 0,
+      step,
+      async () => {
+        if (options.wrap) {
+          runWithoutActiveStep(scheduleContinuation);
+        } else {
+          scheduleContinuation();
+        }
+        return "started";
+      },
+      { tracer, contextWithSpan, criticalPath: false },
+    );
+
+    await execDone;
+    return spans.find((span) => span.name === "sandbox.exec");
+  }
+
+  it("opens an unparented exec span for a process-session bridge continuation", async () => {
+    const execSpan = await runContinuationExec("bridge.process-session", { wrap: true });
+    expect(execSpan).toBeTruthy();
+    // The step span ended and the boundary emptied the store, so the continuation
+    // exec opens a root span, not one under the dead bridge step.
+    expect(execSpan!.parent).toBeNull();
+  });
+
+  it("opens an unparented exec span for a paperclip bridge continuation", async () => {
+    const execSpan = await runContinuationExec("bridge.paperclip", { wrap: true });
+    expect(execSpan).toBeTruthy();
+    expect(execSpan!.parent).toBeNull();
+  });
+
+  it("does not copy the stale criticalPath = false flag onto a continuation exec", async () => {
+    const execSpan = await runContinuationExec("bridge.process-session", { wrap: true });
+    expect(execSpan).toBeTruthy();
+    // The bridge step set `criticalPath: false`. The continuation reads an empty
+    // store, so the exec span records the default `true`, never the stale `false`.
+    expect(execSpan!.attributes[A.execCriticalPath]).toBe(true);
+    expect(execSpan!.attributes[A.execCriticalPath]).not.toBe(false);
+  });
+
+  it("leaks the ended step onto a continuation exec without the boundary wrap", async () => {
+    // The mechanism guard: an unwrapped continuation keeps the ended bridge step
+    // store, so the exec span parents to the dead step and copies its
+    // `criticalPath: false`. The boundary wrap in the two tests above removes both
+    // defects, so this suite fails if a future edit drops the wrap.
+    const { tracer, contextWithSpan, spans } = createRecordingTrace();
+    const runner = await runnerFor({
+      provider: "daytona",
+      execResult: { exitCode: 0, signal: null, timedOut: false, stdout: "", stderr: "" },
+      tracer,
+    });
+
+    let resolveExec!: () => void;
+    const execDone = new Promise<void>((resolve) => {
+      resolveExec = resolve;
+    });
+
+    await measureStartupStep(
+      {},
+      () => 0,
+      "bridge.process-session",
+      async () => {
+        setTimeout(() => {
+          void runner.execute({ command: "echo" }).then(() => resolveExec());
+        }, 0);
+        return "started";
+      },
+      { tracer, contextWithSpan, criticalPath: false },
+    );
+
+    await execDone;
+
+    const stepSpan = spans.find((span) => span.name === "bridge.process-session");
+    const execSpan = spans.find((span) => span.name === "sandbox.exec");
+    expect(stepSpan).toBeTruthy();
+    expect(execSpan).toBeTruthy();
+    // The unwrapped continuation parents the exec span to the ended step and
+    // copies the stale flag.
+    expect(execSpan!.parent).toBe(stepSpan);
+    expect(execSpan!.attributes[A.execCriticalPath]).toBe(false);
+  });
 });