diff --git a/packages/core/src/scheduler/policy.test.ts b/packages/core/src/scheduler/policy.test.ts
index c228ead10d..1618db0701 100644
--- a/packages/core/src/scheduler/policy.test.ts
+++ b/packages/core/src/scheduler/policy.test.ts
@@ -766,6 +766,33 @@ describe('policy.ts', () => {
         }),
       );
     });
+
+    it('should map ProceedAlways to ProceedOnce in Plan Mode', async () => {
+      const mockConfig = {
+        getApprovalMode: vi.fn().mockReturnValue(ApprovalMode.PLAN),
+        setApprovalMode: vi.fn(),
+        getSessionId: vi.fn().mockReturnValue('test-session-id'),
+      } as unknown as Mocked<Config>;
+      (mockConfig as unknown as { config: Config }).config =
+        mockConfig as Config;
+      const mockMessageBus = {
+        publish: vi.fn(),
+      } as unknown as Mocked<MessageBus>;
+      (mockConfig as unknown as { messageBus: MessageBus }).messageBus =
+        mockMessageBus;
+      const tool = { name: 'replace' } as AnyDeclarativeTool;
+
+      await updatePolicy(
+        tool,
+        ToolConfirmationOutcome.ProceedAlways,
+        undefined,
+        mockConfig,
+        mockMessageBus,
+      );
+
+      expect(mockConfig.setApprovalMode).not.toHaveBeenCalled();
+      expect(mockMessageBus.publish).not.toHaveBeenCalled();
+    });
   });
 
   describe('getPolicyDenialError', () => {
diff --git a/packages/core/src/scheduler/policy.ts b/packages/core/src/scheduler/policy.ts
index 69e2a69e6c..c99b5e2998 100644
--- a/packages/core/src/scheduler/policy.ts
+++ b/packages/core/src/scheduler/policy.ts
@@ -119,6 +119,17 @@ export async function updatePolicy(
   messageBus: MessageBus,
   toolInvocation?: AnyToolInvocation,
 ): Promise<void> {
+  const currentMode = context.config.getApprovalMode();
+
+  // If in Plan Mode, map 'Proceed Always' (Allow for this session) to 'Proceed Once' (Allow once)
+  // to prevent transitioning to AUTO_EDIT mode and updating policy.
+  if (
+    currentMode === ApprovalMode.PLAN &&
+    outcome === ToolConfirmationOutcome.ProceedAlways
+  ) {
+    outcome = ToolConfirmationOutcome.ProceedOnce;
+  }
+
   // Mode Transitions (AUTO_EDIT)
   if (isAutoEditTransition(tool, outcome)) {
     context.config.setApprovalMode(ApprovalMode.AUTO_EDIT);
@@ -128,7 +139,6 @@ export async function updatePolicy(
   // Determine persist scope if we are persisting.
   let persistScope: 'workspace' | 'user' | undefined;
   let modes: ApprovalMode[] | undefined;
-  const currentMode = context.config.getApprovalMode();
 
   // If this is an 'Always Allow' selection, we restrict it to the current mode
   // and more permissive modes.