diff --git a/plugins/provider-claude-code/src/bridge/bridge.ts b/plugins/provider-claude-code/src/bridge/bridge.ts
index ed894c471..ffcd8cb9e 100644
--- a/plugins/provider-claude-code/src/bridge/bridge.ts
+++ b/plugins/provider-claude-code/src/bridge/bridge.ts
@@ -2196,6 +2196,17 @@ async function runTurnStart(
       params.threadId,
       withTurnLiveSessionSettings(threadSession.liveSettings, params),
     );
+    // `/plan` on an already-loaded session: the runtime never rebuilds a
+    // bridge session for an option change, so the mode has to be applied to
+    // the live SDK session here (#2019). Leaving plan mode is owned by
+    // restoreApprovedPlanPermissionMode once the plan is approved.
+    if (
+      params.claudeCodePermissionMode === "plan" &&
+      threadSession.permissionMode !== "plan"
+    ) {
+      await threadSession.session.setPermissionMode("plan");
+      threadSession.permissionMode = "plan";
+    }
   } catch (error) {
     const message = error instanceof Error ? error.message : String(error);
     sendError(id, -32000, message);
diff --git a/plugins/provider-claude-code/src/bridge/commands.ts b/plugins/provider-claude-code/src/bridge/commands.ts
index d049024b8..01c44b635 100644
--- a/plugins/provider-claude-code/src/bridge/commands.ts
+++ b/plugins/provider-claude-code/src/bridge/commands.ts
@@ -85,6 +85,7 @@ export const claudeTurnStartParamsSchema = z.object({
   threadId: z.string(),
   providerThreadId: z.string().nullable(),
   input: z.array(z.unknown()),
+  claudeCodePermissionMode: z.literal("plan").optional(),
   model: z.string().optional(),
   reasoningLevel: bridgeReasoningLevelSchema.optional(),
   workflowsEnabled: z.boolean().optional(),
diff --git a/plugins/provider-claude-code/src/session-params.ts b/plugins/provider-claude-code/src/session-params.ts
index 6b2f95b7d..bd2362e8e 100644
--- a/plugins/provider-claude-code/src/session-params.ts
+++ b/plugins/provider-claude-code/src/session-params.ts
@@ -319,6 +319,9 @@ export function buildClaudeTurnParams(
       input: args.input,
       claudeCodePermissionMode: providerOptions.claudeCodePermissionMode,
     }),
+    ...(providerOptions.claudeCodePermissionMode !== undefined
+      ? { claudeCodePermissionMode: providerOptions.claudeCodePermissionMode }
+      : {}),
     ...(args.options.model ? { model: args.options.model } : {}),
     ...(args.options.reasoningLevel
       ? { reasoningLevel: args.options.reasoningLevel }