feat(HAI-065): add file-scope overlap detection with blockedBy tracking

- Add blockedBy field to Task type and core store
- Update scheduler to set blockedBy when deferring tasks due to file-scope overlap
- Render file-scope overlap badge on TaskCard in dashboard
- Add tests for blockedBy store logic, scheduler deferral, and TaskCard badge
- Simplify and refactor existing executor, triage, and CLI command code

packages/dashboard/app/components/TaskCard.tsx

@@ -1,5 +1,5 @@
 import { useCallback, useState } from "react";
-import { Link, Clock } from "lucide-react";
+import { Link, Clock, Layers } from "lucide-react";
 import type { Task, TaskDetail, Column } from "@hai/core";
 import { fetchTaskDetail, uploadAttachment } from "../api";
 import type { ToastType } from "../hooks/useToast";
@@ -139,13 +139,18 @@ export function TaskCard({ task, queued, onOpenDetail, addToast }: TaskCardProps
           </div>
         );
       })()}
-      {((task.dependencies && task.dependencies.length > 0) || queued || task.status === "queued") && (
+      {((task.dependencies && task.dependencies.length > 0) || queued || task.status === "queued" || task.blockedBy) && (
         <div className="card-meta">
           {task.dependencies && task.dependencies.length > 0 && (
             <span className="card-dep-badge" data-tooltip={task.dependencies.join(", ")}>
               <Link size={12} style={{ verticalAlign: 'middle' }} /> {task.dependencies.length} dep{task.dependencies.length > 1 ? "s" : ""}
             </span>
           )}
+          {task.blockedBy && (
+            <span className="card-scope-badge" data-tooltip={`Blocked by ${task.blockedBy} (file overlap)`}>
+              <Layers size={12} style={{ verticalAlign: 'middle' }} /> {task.blockedBy}
+            </span>
+          )}
           {(queued || task.status === "queued") && <span className="queued-badge"><Clock size={12} style={{ verticalAlign: 'middle' }} /> Queued</span>}
         </div>
       )}

packages/dashboard/app/components/__tests__/TaskCard.test.tsx

@@ -166,6 +166,44 @@ describe("TaskCard dependency tooltip", () => {
   });
 });
 
+describe("TaskCard file-scope overlap badge logic", () => {
+  /** Mirrors the card-meta visibility condition from TaskCard.tsx */
+  function shouldShowCardMeta(opts: { dependencies?: string[]; queued?: boolean; status?: string | null; blockedBy?: string }): boolean {
+    const deps = opts.dependencies || [];
+    return deps.length > 0 || !!opts.queued || opts.status === "queued" || !!opts.blockedBy;
+  }
+
+  /** Mirrors the card-scope-badge visibility condition from TaskCard.tsx */
+  function shouldShowScopeBadge(blockedBy?: string): boolean {
+    return !!blockedBy;
+  }
+
+  it("shows scope badge when blockedBy is set", () => {
+    expect(shouldShowScopeBadge("HAI-003")).toBe(true);
+  });
+
+  it("does NOT show scope badge when blockedBy is undefined", () => {
+    expect(shouldShowScopeBadge(undefined)).toBe(false);
+  });
+
+  it("shows card-meta when blockedBy is set even with no deps or queued status", () => {
+    expect(shouldShowCardMeta({ blockedBy: "HAI-003" })).toBe(true);
+  });
+
+  it("does NOT show card-meta when no deps, not queued, and no blockedBy", () => {
+    expect(shouldShowCardMeta({})).toBe(false);
+  });
+
+  /** Mirrors tooltip computation from TaskCard.tsx */
+  function computeScopeTooltip(blockedBy: string): string {
+    return `Blocked by ${blockedBy} (file overlap)`;
+  }
+
+  it("generates correct tooltip text", () => {
+    expect(computeScopeTooltip("HAI-005")).toBe("Blocked by HAI-005 (file overlap)");
+  });
+});
+
 describe("TaskCard queued badge logic", () => {
   /** Mirrors the card-status-badge visibility condition from TaskCard.tsx */
   function shouldShowStatusBadge(status?: string | null): boolean {

packages/dashboard/app/styles.css

@@ -315,6 +315,35 @@ html, body {
   box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
 }
 
+.card-scope-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 3px;
+  font-size: 11px;
+  color: var(--in-progress);
+  position: relative;
+  cursor: default;
+}
+
+.card-scope-badge[data-tooltip]:hover::after {
+  content: attr(data-tooltip);
+  position: absolute;
+  bottom: 100%;
+  left: 50%;
+  transform: translateX(-50%);
+  background: var(--bg-card);
+  color: var(--text);
+  border: 1px solid var(--border);
+  border-radius: 6px;
+  padding: 4px 8px;
+  font-size: 11px;
+  white-space: nowrap;
+  z-index: 10;
+  pointer-events: none;
+  margin-bottom: 4px;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
+}
+
 .card-progress {
   display: flex;
   align-items: center;