feat(HAI-063): add dependency tooltip to TaskCard badge

- Add data-tooltip attribute to card-dep-badge showing comma-separated dependency IDs
- Add CSS hover tooltip using ::after pseudo-element on [data-tooltip]
- Add unit tests for dependency tooltip computation logic
- Remove obsolete TaskDetailModal dependency tooltip tests

packages/dashboard/app/components/TaskCard.tsx

@@ -102,7 +102,7 @@ export function TaskCard({ task, queued, onOpenDetail, addToast }: TaskCardProps
       {((task.dependencies && task.dependencies.length > 0) || queued || task.status === "queued") && (
         <div className="card-meta">
           {task.dependencies && task.dependencies.length > 0 && (
-            <span className="card-dep-badge">
+            <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>
           )}

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

@@ -131,6 +131,31 @@ describe("TaskCard failed status", () => {
   });
 });
 
+describe("TaskCard dependency tooltip", () => {
+  /** Mirrors the data-tooltip computation from TaskCard.tsx */
+  function computeDepTooltip(dependencies: string[]): string | undefined {
+    if (dependencies.length === 0) return undefined;
+    return dependencies.join(", ");
+  }
+
+  it("returns comma-separated dependency IDs when dependencies are present", () => {
+    expect(computeDepTooltip(["HAI-001", "HAI-042"])).toBe("HAI-001, HAI-042");
+  });
+
+  it("returns single dependency ID when only one dependency", () => {
+    expect(computeDepTooltip(["HAI-010"])).toBe("HAI-010");
+  });
+
+  it("returns undefined when dependencies array is empty", () => {
+    expect(computeDepTooltip([])).toBeUndefined();
+  });
+
+  it("handles many dependencies", () => {
+    const deps = ["HAI-001", "HAI-002", "HAI-003", "HAI-004"];
+    expect(computeDepTooltip(deps)).toBe("HAI-001, HAI-002, HAI-003, HAI-004");
+  });
+});
+
 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

@@ -285,6 +285,27 @@ html, body {
   gap: 3px;
   font-size: 11px;
   color: var(--triage);
+  position: relative;
+  cursor: default;
+}
+
+.card-dep-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 {