diff --git a/CHANGELOG.md b/CHANGELOG.md
index 58ff8ba7495..93d91b3a140 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -120,6 +120,7 @@ Docs: https://docs.openclaw.ai
 - Dependencies: refresh workspace dependencies except the pinned Carbon package, and harden ACP session-config writes against non-string SDK values so newer ACP clients fail fast instead of tripping type/runtime mismatches.
 - Gateway/config errors: surface up to three validation issues in top-level `config.set`, `config.patch`, and `config.apply` error messages while preserving structured issue details. (#42664) Thanks @huntharo.
 - Hooks/plugin context parity followup: pass `trigger` and `channelId` through embedded `llm_input`, `agent_end`, and `llm_output` hook contexts so plugins receive the same agent metadata across hook phases. (#42362) Thanks @zhoulf1006.
+- ACP/main session aliases: canonicalize `main` before ACP session lookup so restarted ACP main sessions rehydrate instead of failing closed with `Session is not ACP-enabled: main`. Fixes #25692.
 
 ## 2026.3.8
 
diff --git a/src/acp/control-plane/manager.core.ts b/src/acp/control-plane/manager.core.ts
index 558e1ca24a8..b15aa3bd72e 100644
--- a/src/acp/control-plane/manager.core.ts
+++ b/src/acp/control-plane/manager.core.ts
@@ -44,11 +44,11 @@ import {
   type TurnLatencyStats,
 } from "./manager.types.js";
 import {
+  canonicalizeAcpSessionKey,
   createUnsupportedControlError,
   hasLegacyAcpIdentityProjection,
   normalizeAcpErrorCode,
   normalizeActorKey,
-  normalizeSessionKey,
   requireReadySessionMeta,
   resolveAcpAgentFromSessionKey,
   resolveAcpSessionResolutionError,
@@ -87,7 +87,7 @@ export class AcpSessionManager {
   constructor(private readonly deps: AcpSessionManagerDeps = DEFAULT_DEPS) {}
 
   resolveSession(params: { cfg: OpenClawConfig; sessionKey: string }): AcpSessionResolution {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       return {
         kind: "none",
@@ -213,7 +213,10 @@ export class AcpSessionManager {
     handle: AcpRuntimeHandle;
     meta: SessionAcpMeta;
   }> {
-    const sessionKey = normalizeSessionKey(input.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey({
+      cfg: input.cfg,
+      sessionKey: input.sessionKey,
+    });
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -321,7 +324,7 @@ export class AcpSessionManager {
     sessionKey: string;
     signal?: AbortSignal;
   }): Promise<AcpSessionStatus> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -397,7 +400,7 @@ export class AcpSessionManager {
     sessionKey: string;
     runtimeMode: string;
   }): Promise<AcpSessionRuntimeOptions> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -452,7 +455,7 @@ export class AcpSessionManager {
     key: string;
     value: string;
   }): Promise<AcpSessionRuntimeOptions> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -525,7 +528,7 @@ export class AcpSessionManager {
     sessionKey: string;
     patch: Partial<AcpSessionRuntimeOptions>;
   }): Promise<AcpSessionRuntimeOptions> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     const validatedPatch = validateRuntimeOptionPatch(params.patch);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
@@ -555,7 +558,7 @@ export class AcpSessionManager {
     cfg: OpenClawConfig;
     sessionKey: string;
   }): Promise<AcpSessionRuntimeOptions> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -591,7 +594,10 @@ export class AcpSessionManager {
   }
 
   async runTurn(input: AcpRunTurnInput): Promise<void> {
-    const sessionKey = normalizeSessionKey(input.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey({
+      cfg: input.cfg,
+      sessionKey: input.sessionKey,
+    });
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -738,7 +744,7 @@ export class AcpSessionManager {
     sessionKey: string;
     reason?: string;
   }): Promise<void> {
-    const sessionKey = normalizeSessionKey(params.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey(params);
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
@@ -806,7 +812,10 @@ export class AcpSessionManager {
   }
 
   async closeSession(input: AcpCloseSessionInput): Promise<AcpCloseSessionResult> {
-    const sessionKey = normalizeSessionKey(input.sessionKey);
+    const sessionKey = canonicalizeAcpSessionKey({
+      cfg: input.cfg,
+      sessionKey: input.sessionKey,
+    });
     if (!sessionKey) {
       throw new AcpRuntimeError("ACP_SESSION_INIT_FAILED", "ACP session key is required.");
     }
diff --git a/src/acp/control-plane/manager.test.ts b/src/acp/control-plane/manager.test.ts
index ebdf356ca9f..68d9cb2f875 100644
--- a/src/acp/control-plane/manager.test.ts
+++ b/src/acp/control-plane/manager.test.ts
@@ -170,6 +170,52 @@ describe("AcpSessionManager", () => {
     expect(resolved.error.message).toContain("ACP metadata is missing");
   });
 
+  it("canonicalizes the main alias before ACP rehydrate after restart", async () => {
+    const runtimeState = createRuntime();
+    hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
+      id: "acpx",
+      runtime: runtimeState.runtime,
+    });
+    hoisted.readAcpSessionEntryMock.mockImplementation((paramsUnknown: unknown) => {
+      const sessionKey = (paramsUnknown as { sessionKey?: string }).sessionKey;
+      if (sessionKey !== "agent:main:main") {
+        return null;
+      }
+      return {
+        sessionKey,
+        storeSessionKey: sessionKey,
+        acp: readySessionMeta(),
+      };
+    });
+
+    const manager = new AcpSessionManager();
+    const cfg = {
+      ...baseCfg,
+      session: { mainKey: "main" },
+      agents: { list: [{ id: "main", default: true }] },
+    } as OpenClawConfig;
+
+    await manager.runTurn({
+      cfg,
+      sessionKey: "main",
+      text: "after restart",
+      mode: "prompt",
+      requestId: "r-main",
+    });
+
+    expect(hoisted.readAcpSessionEntryMock).toHaveBeenCalledWith(
+      expect.objectContaining({
+        cfg,
+        sessionKey: "agent:main:main",
+      }),
+    );
+    expect(runtimeState.ensureSession).toHaveBeenCalledWith(
+      expect.objectContaining({
+        sessionKey: "agent:main:main",
+      }),
+    );
+  });
+
   it("serializes concurrent turns for the same ACP session", async () => {
     const runtimeState = createRuntime();
     hoisted.requireAcpRuntimeBackendMock.mockReturnValue({
diff --git a/src/acp/control-plane/manager.utils.ts b/src/acp/control-plane/manager.utils.ts
index 17729c6c2fc..90f7c516538 100644
--- a/src/acp/control-plane/manager.utils.ts
+++ b/src/acp/control-plane/manager.utils.ts
@@ -1,6 +1,14 @@
 import type { OpenClawConfig } from "../../config/config.js";
+import {
+  canonicalizeMainSessionAlias,
+  resolveMainSessionKey,
+} from "../../config/sessions/main-session.js";
 import type { SessionAcpMeta } from "../../config/sessions/types.js";
-import { normalizeAgentId, parseAgentSessionKey } from "../../routing/session-key.js";
+import {
+  normalizeAgentId,
+  normalizeMainKey,
+  parseAgentSessionKey,
+} from "../../routing/session-key.js";
 import { ACP_ERROR_CODES, AcpRuntimeError } from "../runtime/errors.js";
 import type { AcpSessionResolution } from "./manager.types.js";
 
@@ -42,6 +50,33 @@ export function normalizeSessionKey(sessionKey: string): string {
   return sessionKey.trim();
 }
 
+export function canonicalizeAcpSessionKey(params: {
+  cfg: OpenClawConfig;
+  sessionKey: string;
+}): string {
+  const normalized = normalizeSessionKey(params.sessionKey);
+  if (!normalized) {
+    return "";
+  }
+  const lowered = normalized.toLowerCase();
+  if (lowered === "global" || lowered === "unknown") {
+    return lowered;
+  }
+  const parsed = parseAgentSessionKey(lowered);
+  if (parsed) {
+    return canonicalizeMainSessionAlias({
+      cfg: params.cfg,
+      agentId: parsed.agentId,
+      sessionKey: lowered,
+    });
+  }
+  const mainKey = normalizeMainKey(params.cfg.session?.mainKey);
+  if (lowered === "main" || lowered === mainKey) {
+    return resolveMainSessionKey(params.cfg);
+  }
+  return lowered;
+}
+
 export function normalizeActorKey(sessionKey: string): string {
   return sessionKey.trim().toLowerCase();
 }