feat(HAI-002): add maxWorktrees setting to limit total git worktrees

- Add maxWorktrees field to Settings interface with default of 4
- Enforce worktree limit in Scheduler.schedule() alongside maxConcurrent
- Wire setting through dashboard startup from persisted settings
- Include maxWorktrees in /api/config response
- Add Max Worktrees input to Settings Modal UI
- Backward compatible: existing configs without maxWorktrees use default

packages/cli/src/commands/dashboard.ts

@@ -49,8 +49,11 @@ export async function runDashboard(port: number, opts: { engine?: boolean; open?
       onError: (t, e) => console.log(`[engine] ✗ ${t.id}: ${e.message}`),
     });
 
+    const settings = await store.getSettings();
+
     const scheduler = new Scheduler(store, {
-      maxConcurrent: 2,
+      maxConcurrent: settings.maxConcurrent,
+      maxWorktrees: settings.maxWorktrees,
       onSchedule: (t) => console.log(`[engine] Scheduled ${t.id}`),
       onBlocked: (t, deps) => console.log(`[engine] ${t.id} blocked by ${deps.join(", ")}`),
     });

packages/core/src/types.ts

@@ -43,11 +43,13 @@ export interface TaskCreateInput {
 
 export interface Settings {
   maxConcurrent: number;
+  maxWorktrees: number;
   pollIntervalMs: number;
 }
 
 export const DEFAULT_SETTINGS: Settings = {
   maxConcurrent: 2,
+  maxWorktrees: 4,
   pollIntervalMs: 15000,
 };
 

packages/dashboard/app/components/SettingsModal.tsx

@@ -9,7 +9,7 @@ interface SettingsModalProps {
 }
 
 export function SettingsModal({ onClose, addToast }: SettingsModalProps) {
-  const [form, setForm] = useState<Settings>({ maxConcurrent: 2, pollIntervalMs: 15000 });
+  const [form, setForm] = useState<Settings>({ maxConcurrent: 2, maxWorktrees: 4, pollIntervalMs: 15000 });
   const [loading, setLoading] = useState(true);
 
   useEffect(() => {
@@ -75,6 +75,20 @@ export function SettingsModal({ onClose, addToast }: SettingsModalProps) {
                 }
               />
             </div>
+            <div className="form-group">
+              <label htmlFor="maxWorktrees">Max Worktrees</label>
+              <input
+                id="maxWorktrees"
+                type="number"
+                min={1}
+                max={20}
+                value={form.maxWorktrees}
+                onChange={(e) =>
+                  setForm((f) => ({ ...f, maxWorktrees: Number(e.target.value) }))
+                }
+              />
+              <small>Limits total git worktrees including in-review tasks</small>
+            </div>
             <div className="form-group">
               <label htmlFor="pollIntervalMs">Poll Interval (ms)</label>
               <input

packages/dashboard/src/routes.ts

@@ -10,9 +10,12 @@ export function createApiRoutes(store: TaskStore, options?: ServerOptions): Rout
   router.get("/config", async (_req, res) => {
     try {
       const settings = await store.getSettings();
-      res.json({ maxConcurrent: settings.maxConcurrent ?? options?.maxConcurrent ?? 2 });
+      res.json({
+        maxConcurrent: settings.maxConcurrent ?? options?.maxConcurrent ?? 2,
+        maxWorktrees: settings.maxWorktrees ?? 4,
+      });
     } catch {
-      res.json({ maxConcurrent: options?.maxConcurrent ?? 2 });
+      res.json({ maxConcurrent: options?.maxConcurrent ?? 2, maxWorktrees: 4 });
     }
   });
 

packages/engine/src/scheduler.ts

@@ -3,6 +3,8 @@ import { resolveDependencyOrder, type TaskStore, type Task } from "@hai/core";
 export interface SchedulerOptions {
   /** Max concurrent in-progress tasks. Default: 2 */
   maxConcurrent?: number;
+  /** Max total worktrees (in-progress + in-review with worktree). Default: 4 */
+  maxWorktrees?: number;
   /** Milliseconds between scheduling polls. Default: 15000 */
   pollIntervalMs?: number;
   /** Called when scheduler starts a task */
@@ -36,7 +38,7 @@ export class Scheduler {
     this.pollInterval = setInterval(() => this.schedule(), interval);
     this.schedule();
     console.log(
-      `[scheduler] Started (max concurrent: ${this.options.maxConcurrent ?? 2})`,
+      `[scheduler] Started (max concurrent: ${this.options.maxConcurrent ?? 2}, max worktrees: ${this.options.maxWorktrees ?? 4})`,
     );
   }
 
@@ -56,9 +58,27 @@ export class Scheduler {
     try {
       const tasks = await this.store.listTasks();
       const maxConcurrent = this.options.maxConcurrent ?? 2;
+      const maxWorktrees = this.options.maxWorktrees ?? 4;
+
+      // Count all tasks with active worktrees (in-progress or in-review with worktree set)
+      const activeWorktrees = tasks.filter(
+        (t) =>
+          t.column === "in-progress" ||
+          (t.column === "in-review" && t.worktree),
+      ).length;
+
+      if (activeWorktrees >= maxWorktrees) {
+        console.log(
+          `[scheduler] Worktree limit reached (${activeWorktrees}/${maxWorktrees})`,
+        );
+        return;
+      }
 
       const inProgress = tasks.filter((t) => t.column === "in-progress");
-      const available = maxConcurrent - inProgress.length;
+      const available = Math.min(
+        maxConcurrent - inProgress.length,
+        maxWorktrees - activeWorktrees,
+      );
       if (available <= 0) return;
 
       const todo = tasks.filter((t) => t.column === "todo");