diff --git a/scripts/lib/tmux-worktree-orchestrator.js b/scripts/lib/tmux-worktree-orchestrator.js
index 8eb947c8..4c9cfa92 100644
--- a/scripts/lib/tmux-worktree-orchestrator.js
+++ b/scripts/lib/tmux-worktree-orchestrator.js
@@ -190,6 +190,7 @@ function buildOrchestrationPlan(config = {}) {
     throw new Error('buildOrchestrationPlan requires at least one worker');
   }
 
+  const seenSlugs = new Set();
   const workerPlans = workers.map((worker, index) => {
     if (!worker || typeof worker.task !== 'string' || worker.task.trim().length === 0) {
       throw new Error(`Worker ${index + 1} is missing a task`);
@@ -197,6 +198,12 @@ function buildOrchestrationPlan(config = {}) {
 
     const workerName = worker.name || `worker-${index + 1}`;
     const workerSlug = slugify(workerName, `worker-${index + 1}`);
+
+    if (seenSlugs.has(workerSlug)) {
+      throw new Error(`Workers must have unique slugs — duplicate: ${workerSlug}`);
+    }
+    seenSlugs.add(workerSlug);
+
     const branchName = `orchestrator-${sessionName}-${workerSlug}`;
     const worktreePath = path.join(worktreeRoot, `${repoName}-${sessionName}-${workerSlug}`);
     const workerCoordinationDir = path.join(coordinationDir, workerSlug);
@@ -206,7 +213,7 @@ function buildOrchestrationPlan(config = {}) {
     const launcherCommand = worker.launcherCommand || defaultLauncher;
     const workerSeedPaths = normalizeSeedPaths(worker.seedPaths, repoRoot);
     const seedPaths = normalizeSeedPaths([...globalSeedPaths, ...workerSeedPaths], repoRoot);
-    const templateVariables = {
+    const templateVariables = buildTemplateVariables({
       branch_name: branchName,
       handoff_file: handoffFilePath,
       repo_root: repoRoot,
@@ -216,7 +223,7 @@ function buildOrchestrationPlan(config = {}) {
       worker_name: workerName,
       worker_slug: workerSlug,
       worktree_path: worktreePath
-    };
+    });
 
     if (!launcherCommand) {
       throw new Error(`Worker ${workerName} is missing a launcherCommand`);