diff --git a/docs/cli/acp.md b/docs/cli/acp.md
index 13a8090c4625..6aeda4fdeb20 100644
--- a/docs/cli/acp.md
+++ b/docs/cli/acp.md
@@ -63,7 +63,7 @@ Quick rule:
   fallback and do not reconstruct historic tool calls or system notices.
 - If multiple ACP clients share the same Gateway session key, event and cancel
   routing are best-effort rather than strictly isolated per client. Prefer the
-  default isolated `acp:<uuid>` sessions when you need clean editor-local
+  default isolated `acp-bridge:<uuid>` sessions when you need clean editor-local
   turns.
 - Gateway stop states are translated into ACP stop reasons, but that mapping is
   less expressive than a fully ACP-native runtime.
@@ -206,7 +206,7 @@ openclaw acp --session agent:qa:bug-123
 ```
 
 Each ACP session maps to a single Gateway session key. One agent can have many
-sessions; ACP defaults to an isolated `acp:<uuid>` session unless you override
+sessions; ACP defaults to an isolated `acp-bridge:<uuid>` session unless you override
 the key or label.
 
 Per-session `mcpServers` are not supported in bridge mode. If an ACP client
@@ -309,8 +309,10 @@ In Zed, open the Agent panel and select "OpenClaw ACP" to start a thread.
 
 ## Session mapping
 
-By default, ACP sessions get an isolated Gateway session key with an `acp:` prefix.
-To reuse a known session, pass a session key or label:
+By default, ACP bridge sessions get an isolated Gateway session key with an
+`acp-bridge:` prefix. These normal-model bridge sessions are synthetic and
+subject to stale-entry pruning and entry-count caps. To reuse a known session,
+pass a session key or label:
 
 - `--session <key>`: use a specific Gateway session key.
 - `--session-label <label>`: resolve an existing session by label.
diff --git a/src/acp/translator.session-setup.test.ts b/src/acp/translator.session-setup.test.ts
index 7f517cf02c92..1eb62a3265e2 100644
--- a/src/acp/translator.session-setup.test.ts
+++ b/src/acp/translator.session-setup.test.ts
@@ -2,6 +2,7 @@
 import { createInMemorySessionStore } from "@openclaw/acp-core/session";
 import { describe, expect, it, vi } from "vitest";
 import type { GatewayClient } from "../gateway/client.js";
+import { isAcpSessionKey } from "../sessions/session-key-utils.js";
 import {
   createNewSessionRequest,
   createLoadSessionRequest,
@@ -59,6 +60,21 @@ describe("acp unsupported bridge session setup", () => {
 });
 
 describe("acp session UX bridge behavior", () => {
+  it("uses a non-runtime namespace for generated bridge sessions", async () => {
+    const sessionStore = createInMemorySessionStore();
+    const agent = new AcpGatewayAgent(createAcpConnection(), createAcpGateway(), {
+      sessionStore,
+    });
+
+    const result = await agent.newSession(createNewSessionRequest());
+    const sessionKey = sessionStore.getSession(result.sessionId)?.sessionKey;
+
+    expect(sessionKey).toMatch(/^acp-bridge:/);
+    expect(isAcpSessionKey(sessionKey)).toBe(false);
+
+    sessionStore.clearAllSessionsForTest();
+  });
+
   it("returns initial modes and thought-level config options for new sessions", async () => {
     const sessionStore = createInMemorySessionStore();
     const agent = new AcpGatewayAgent(createAcpConnection(), createAcpGateway(), {
diff --git a/src/acp/translator.ts b/src/acp/translator.ts
index 786abfc40a39..720f08f22e98 100644
--- a/src/acp/translator.ts
+++ b/src/acp/translator.ts
@@ -374,7 +374,7 @@ export class AcpGatewayAgent implements Agent {
     const meta = parseSessionMeta(params["_meta"]);
     const sessionKey = await this.resolveSessionKeyFromMeta({
       meta,
-      fallbackKey: `acp:${sessionId}`,
+      fallbackKey: `acp-bridge:${sessionId}`,
     });
 
     const session = this.sessionStore.createSession({
diff --git a/src/config/sessions/store-maintenance.ts b/src/config/sessions/store-maintenance.ts
index ff259e93b972..1bdba1f6fa35 100644
--- a/src/config/sessions/store-maintenance.ts
+++ b/src/config/sessions/store-maintenance.ts
@@ -308,10 +308,12 @@ function getEntryUpdatedAt(entry?: SessionEntry): number {
 function isSyntheticSessionMaintenanceKey(sessionKey: string): boolean {
   const parsed = parseAgentSessionKey(sessionKey);
   const rest = normalizeLowercaseStringOrEmpty(parsed?.rest ?? sessionKey);
+  // ACP bridge sessions use normal model dispatch, but remain synthetic and disposable.
   return (
     isSubagentSessionKey(sessionKey) ||
     isAcpSessionKey(sessionKey) ||
     isCronSessionKey(sessionKey) ||
+    rest.startsWith("acp-bridge:") ||
     rest.startsWith("hook:") ||
     rest.startsWith("node:") ||
     rest === "heartbeat" ||
diff --git a/src/config/sessions/store.pruning.test.ts b/src/config/sessions/store.pruning.test.ts
index c2cc5bc8b76c..20899f6d74df 100644
--- a/src/config/sessions/store.pruning.test.ts
+++ b/src/config/sessions/store.pruning.test.ts
@@ -266,6 +266,15 @@ describe("capEntryCount", () => {
 });
 
 describe("isProtectedSessionMaintenanceEntry", () => {
+  it("treats generated ACP bridge sessions as disposable", () => {
+    expect(
+      isProtectedSessionMaintenanceEntry("agent:main:acp-bridge:session-1", {
+        ...makeEntry(Date.now()),
+        chatType: "group",
+      }),
+    ).toBe(false);
+  });
+
   it("does not protect synthetic sessions just because they carry group metadata", () => {
     expect(
       isProtectedSessionMaintenanceEntry("agent:main:subagent:worker", {