diff --git a/apps/frontend/src/main/ipc-handlers/task/worktree-handlers.ts b/apps/frontend/src/main/ipc-handlers/task/worktree-handlers.ts
index f159983b..f6f1d289 100644
--- a/apps/frontend/src/main/ipc-handlers/task/worktree-handlers.ts
+++ b/apps/frontend/src/main/ipc-handlers/task/worktree-handlers.ts
@@ -554,23 +554,37 @@ export function registerWorktreeHandlers(
               }
 
               // Persist the status change to implementation_plan.json
-              const planPath = path.join(specDir, AUTO_BUILD_PATHS.IMPLEMENTATION_PLAN);
-              try {
-                if (existsSync(planPath)) {
-                  const { readFileSync, writeFileSync } = require('fs');
-                  const planContent = readFileSync(planPath, 'utf-8');
-                  const plan = JSON.parse(planContent);
-                  plan.status = newStatus;
-                  plan.planStatus = planStatus;
-                  plan.updated_at = new Date().toISOString();
-                  if (staged) {
-                    plan.stagedAt = new Date().toISOString();
-                    plan.stagedInMainProject = true;
+              // Issue #243: We must update BOTH the main project's plan AND the worktree's plan (if it exists)
+              // because ProjectStore prefers the worktree version when deduplicating tasks.
+              const planPaths = [
+                path.join(specDir, AUTO_BUILD_PATHS.IMPLEMENTATION_PLAN), // Main project
+                path.join(worktreePath, AUTO_BUILD_PATHS.IMPLEMENTATION_PLAN) // Worktree
+              ];
+
+              const { readFileSync, writeFileSync } = require('fs');
+
+              for (const planPath of planPaths) {
+                try {
+                  if (existsSync(planPath)) {
+                    const planContent = readFileSync(planPath, 'utf-8');
+                    const plan = JSON.parse(planContent);
+                    plan.status = newStatus;
+                    plan.planStatus = planStatus;
+                    plan.updated_at = new Date().toISOString();
+                    if (staged) {
+                      plan.stagedAt = new Date().toISOString();
+                      plan.stagedInMainProject = true;
+                    }
+                    writeFileSync(planPath, JSON.stringify(plan, null, 2));
+                  }
+                } catch (persistError) {
+                  // Only log error if main plan fails; worktree plan might legitimately be missing or read-only
+                  if (planPath.includes(specDir)) {
+                    console.error('Failed to persist task status to main plan:', persistError);
+                  } else {
+                    debug('Failed to persist task status to worktree plan (non-critical):', persistError);
                   }
-                  writeFileSync(planPath, JSON.stringify(plan, null, 2));
                 }
-              } catch (persistError) {
-                console.error('Failed to persist task status:', persistError);
               }
 
               const mainWindow = getMainWindow();