diff --git a/src/acp/control-plane/manager.core.ts b/src/acp/control-plane/manager.core.ts
index 58f74b72918..d92dd388f05 100644
--- a/src/acp/control-plane/manager.core.ts
+++ b/src/acp/control-plane/manager.core.ts
@@ -12,6 +12,7 @@ import {
   identityEquals,
   isSessionIdentityPending,
   mergeSessionIdentity,
+  resolveRuntimeResumeSessionId,
   resolveRuntimeHandleIdentifiersFromIdentity,
   resolveSessionIdentityFromMeta,
 } from "../runtime/session-identity.js";
@@ -972,20 +973,45 @@ export class AcpSessionManager {
 
     const backend = this.deps.requireRuntimeBackend(configuredBackend || undefined);
     const runtime = backend.runtime;
-    const ensured = await withAcpRuntimeErrorBoundary({
-      run: async () =>
-        await runtime.ensureSession({
-          sessionKey: params.sessionKey,
-          agent,
-          mode,
-          cwd,
-        }),
-      fallbackCode: "ACP_SESSION_INIT_FAILED",
-      fallbackMessage: "Could not initialize ACP session runtime.",
-    });
-
     const previousMeta = params.meta;
     const previousIdentity = resolveSessionIdentityFromMeta(previousMeta);
+    const persistedResumeSessionId =
+      mode === "persistent" ? resolveRuntimeResumeSessionId(previousIdentity) : undefined;
+    const ensureSession = async (resumeSessionId?: string) =>
+      await withAcpRuntimeErrorBoundary({
+        run: async () =>
+          await runtime.ensureSession({
+            sessionKey: params.sessionKey,
+            agent,
+            mode,
+            ...(resumeSessionId ? { resumeSessionId } : {}),
+            cwd,
+          }),
+        fallbackCode: "ACP_SESSION_INIT_FAILED",
+        fallbackMessage: "Could not initialize ACP session runtime.",
+      });
+    let ensured: AcpRuntimeHandle;
+    if (persistedResumeSessionId) {
+      try {
+        ensured = await ensureSession(persistedResumeSessionId);
+      } catch (error) {
+        const acpError = toAcpRuntimeError({
+          error,
+          fallbackCode: "ACP_SESSION_INIT_FAILED",
+          fallbackMessage: "Could not initialize ACP session runtime.",
+        });
+        if (acpError.code !== "ACP_SESSION_INIT_FAILED") {
+          throw acpError;
+        }
+        logVerbose(
+          `acp-manager: resume init failed for ${params.sessionKey}; retrying without persisted ACP session id: ${acpError.message}`,
+        );
+        ensured = await ensureSession();
+      }
+    } else {
+      ensured = await ensureSession();
+    }
+
     const now = Date.now();
     const effectiveCwd = normalizeText(ensured.cwd) ?? cwd;
     const nextRuntimeOptions = normalizeRuntimeOptions({
diff --git a/src/acp/control-plane/manager.test.ts b/src/acp/control-plane/manager.test.ts
index 7229e34914d..4f5d316c393 100644
--- a/src/acp/control-plane/manager.test.ts
+++ b/src/acp/control-plane/manager.test.ts
@@ -432,6 +432,186 @@ describe("AcpSessionManager", () => {
     expect(runtimeState.ensureSession).toHaveBeenCalledTimes(2);
   });
 
+  it("passes persisted ACP backend session identity back into ensureSession for configured bindings after restart", async () => {
+    const runtimeState = createRuntime();
+    hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
+      id: "acpx",
+      runtime: runtimeState.runtime,
+    });
+    const sessionKey = "agent:codex:acp:binding:discord:default:deadbeef";
+    hoisted.readAcpSessionEntryMock.mockImplementation((paramsUnknown: unknown) => {
+      const key = (paramsUnknown as { sessionKey?: string }).sessionKey ?? sessionKey;
+      return {
+        sessionKey: key,
+        storeSessionKey: key,
+        acp: {
+          ...readySessionMeta(),
+          runtimeSessionName: key,
+          identity: {
+            state: "resolved",
+            source: "status",
+            acpxSessionId: "acpx-sid-1",
+            lastUpdatedAt: Date.now(),
+          },
+        },
+      };
+    });
+
+    const manager = new AcpSessionManager();
+    await manager.runTurn({
+      cfg: baseCfg,
+      sessionKey,
+      text: "after restart",
+      mode: "prompt",
+      requestId: "r-binding-restart",
+    });
+
+    expect(runtimeState.ensureSession).toHaveBeenCalledWith(
+      expect.objectContaining({
+        sessionKey,
+        agent: "codex",
+        resumeSessionId: "acpx-sid-1",
+      }),
+    );
+  });
+
+  it("does not resume persisted ACP identity for oneshot sessions after restart", async () => {
+    const runtimeState = createRuntime();
+    hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
+      id: "acpx",
+      runtime: runtimeState.runtime,
+    });
+    const sessionKey = "agent:codex:acp:binding:discord:default:oneshot";
+    hoisted.readAcpSessionEntryMock.mockImplementation((paramsUnknown: unknown) => {
+      const key = (paramsUnknown as { sessionKey?: string }).sessionKey ?? sessionKey;
+      return {
+        sessionKey: key,
+        storeSessionKey: key,
+        acp: {
+          ...readySessionMeta(),
+          runtimeSessionName: key,
+          mode: "oneshot",
+          identity: {
+            state: "resolved",
+            source: "status",
+            acpxSessionId: "acpx-sid-oneshot",
+            lastUpdatedAt: Date.now(),
+          },
+        },
+      };
+    });
+
+    const manager = new AcpSessionManager();
+    await manager.runTurn({
+      cfg: baseCfg,
+      sessionKey,
+      text: "after restart",
+      mode: "prompt",
+      requestId: "r-binding-oneshot",
+    });
+
+    expect(runtimeState.ensureSession).toHaveBeenCalledTimes(1);
+    const ensureInput = runtimeState.ensureSession.mock.calls[0]?.[0] as
+      | { resumeSessionId?: string; mode?: string }
+      | undefined;
+    expect(ensureInput).toMatchObject({
+      sessionKey,
+      agent: "codex",
+      mode: "oneshot",
+    });
+    expect(ensureInput?.resumeSessionId).toBeUndefined();
+  });
+
+  it("falls back to a fresh ensure when reopening a persisted ACP backend session id fails", async () => {
+    const runtimeState = createRuntime();
+    runtimeState.ensureSession.mockImplementation(async (inputUnknown: unknown) => {
+      const input = inputUnknown as {
+        sessionKey: string;
+        agent: string;
+        mode: "persistent" | "oneshot";
+        resumeSessionId?: string;
+      };
+      if (input.resumeSessionId) {
+        throw new AcpRuntimeError(
+          "ACP_SESSION_INIT_FAILED",
+          "failed to resume persisted ACP session",
+        );
+      }
+      return {
+        sessionKey: input.sessionKey,
+        backend: "acpx",
+        runtimeSessionName: `${input.sessionKey}:${input.mode}:runtime`,
+        backendSessionId: "acpx-sid-fresh",
+      };
+    });
+    runtimeState.getStatus.mockResolvedValue({
+      summary: "status=alive",
+      backendSessionId: "acpx-sid-fresh",
+      details: { status: "alive" },
+    });
+    hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
+      id: "acpx",
+      runtime: runtimeState.runtime,
+    });
+    const sessionKey = "agent:codex:acp:binding:discord:default:retry-fresh";
+    let currentMeta: SessionAcpMeta = {
+      ...readySessionMeta(),
+      runtimeSessionName: sessionKey,
+      identity: {
+        state: "resolved",
+        source: "status",
+        acpxSessionId: "acpx-sid-stale",
+        lastUpdatedAt: Date.now(),
+      },
+    };
+    hoisted.readAcpSessionEntryMock.mockImplementation((paramsUnknown: unknown) => {
+      const key = (paramsUnknown as { sessionKey?: string }).sessionKey ?? sessionKey;
+      return {
+        sessionKey: key,
+        storeSessionKey: key,
+        acp: currentMeta,
+      };
+    });
+    hoisted.upsertAcpSessionMetaMock.mockImplementation(async (paramsUnknown: unknown) => {
+      const params = paramsUnknown as {
+        mutate: (
+          current: SessionAcpMeta | undefined,
+          entry: { acp?: SessionAcpMeta } | undefined,
+        ) => SessionAcpMeta | null | undefined;
+      };
+      const next = params.mutate(currentMeta, { acp: currentMeta });
+      if (next) {
+        currentMeta = next;
+      }
+      return {
+        sessionId: "session-1",
+        updatedAt: Date.now(),
+        acp: currentMeta,
+      };
+    });
+
+    const manager = new AcpSessionManager();
+    await manager.runTurn({
+      cfg: baseCfg,
+      sessionKey,
+      text: "after restart",
+      mode: "prompt",
+      requestId: "r-binding-retry-fresh",
+    });
+
+    expect(runtimeState.ensureSession).toHaveBeenCalledTimes(2);
+    expect(runtimeState.ensureSession.mock.calls[0]?.[0]).toMatchObject({
+      sessionKey,
+      agent: "codex",
+      resumeSessionId: "acpx-sid-stale",
+    });
+    const retryInput = runtimeState.ensureSession.mock.calls[1]?.[0] as
+      | { resumeSessionId?: string }
+      | undefined;
+    expect(retryInput?.resumeSessionId).toBeUndefined();
+    expect(currentMeta.identity?.acpxSessionId).toBe("acpx-sid-fresh");
+  });
+
   it("enforces acp.maxConcurrentSessions when opening new runtime handles", async () => {
     const runtimeState = createRuntime();
     hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
diff --git a/src/acp/runtime/session-identity.ts b/src/acp/runtime/session-identity.ts
index 066a3cb71e5..1ff808bd28c 100644
--- a/src/acp/runtime/session-identity.ts
+++ b/src/acp/runtime/session-identity.ts
@@ -71,6 +71,15 @@ export function identityHasStableSessionId(identity: SessionAcpIdentity | undefi
   return Boolean(identity?.acpxSessionId || identity?.agentSessionId);
 }
 
+export function resolveRuntimeResumeSessionId(
+  identity: SessionAcpIdentity | undefined,
+): string | undefined {
+  if (!identity) {
+    return undefined;
+  }
+  return normalizeText(identity.acpxSessionId) ?? normalizeText(identity.agentSessionId);
+}
+
 export function isSessionIdentityPending(identity: SessionAcpIdentity | undefined): boolean {
   if (!identity) {
     return true;