feat(drill): DrillableCell — hover-reveal button wrapper

src/components/drill/DrillableCell.test.tsx

@@ -0,0 +1,37 @@
+// @vitest-environment happy-dom
+(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+import { afterEach, describe, it, expect, vi } from "vitest";
+import { cleanup, render, screen, fireEvent } from "@testing-library/react";
+import { DrillableCell } from "@/components/drill/DrillableCell";
+
+// happy-dom keeps `document.body` between tests; without cleanup,
+// `screen.getByRole("button")` finds buttons from earlier renders.
+afterEach(() => cleanup());
+
+describe("DrillableCell", () => {
+  it("renders children, applies hover affordance classes, calls onClick", () => {
+    const onClick = vi.fn();
+    render(
+      <DrillableCell onClick={onClick}>
+        <span>CLM-114</span>
+      </DrillableCell>,
+    );
+    const btn = screen.getByRole("button") as HTMLButtonElement;
+    expect(btn.classList.contains("drillable")).toBe(true);
+    fireEvent.click(btn);
+    expect(onClick).toHaveBeenCalledOnce();
+  });
+
+  it("disabled state hides affordance and blocks click", () => {
+    const onClick = vi.fn();
+    render(
+      <DrillableCell onClick={onClick} disabled>
+        <span>unavailable</span>
+      </DrillableCell>,
+    );
+    const btn = screen.getByRole("button") as HTMLButtonElement;
+    expect(btn.disabled).toBe(true);
+    expect(btn.classList.contains("drillable")).toBe(false);
+  });
+});

src/components/drill/DrillableCell.tsx

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+import type { ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+interface Props {
+  children: ReactNode;
+  onClick: () => void;
+  disabled?: boolean;
+  /** Optional aria-label; defaults to the visible text content. */
+  ariaLabel?: string;
+}
+
+/**
+ * Wrap any clickable cell with hover-reveal affordance:
+ *   cursor: pointer + accent background tint + trailing "›" chevron,
+ *   applied via the `drillable` class on hover (see `src/index.css`
+ *   in Task 1.4).
+ *
+ * Renders as a <button> (disabled when `disabled`) so it gets keyboard
+ * activation (Enter/Space) and the standard disabled-button semantics.
+ * The `drillable` affordance class is omitted when disabled.
+ */
+export function DrillableCell({ children, onClick, disabled, ariaLabel }: Props) {
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      disabled={disabled}
+      aria-label={ariaLabel}
+      className={cn(
+        !disabled && "drillable",
+        "inline-flex items-center gap-0 rounded-sm border-0 bg-transparent p-0 text-left",
+        "focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-1",
+        disabled && "text-muted-foreground cursor-not-allowed",
+      )}
+    >
+      {children}
+    </button>
+  );
+}