diff --git a/packages/core-eslint/rules/_usecase-name.js b/packages/core-eslint/rules/_usecase-name.js
new file mode 100644
index 0000000..c8299b8
--- /dev/null
+++ b/packages/core-eslint/rules/_usecase-name.js
@@ -0,0 +1,17 @@
+/**
+ * Derive the manifest use-case key from a use-case file path.
+ *
+ * Convention: `packages/<feature>/src/application/use-cases/<kebab-slug>.use-case.ts`
+ * → manifest.useCases.<camelCaseSlug>
+ *
+ * Returns null for non-use-case files.
+ */
+export function useCaseNameFromFile(filepath) {
+  if (!filepath.endsWith(".use-case.ts")) return null;
+  if (!filepath.includes("/application/use-cases/") && !filepath.includes("\\application\\use-cases\\")) {
+    return null;
+  }
+  const base = filepath.split(/[\\/]/).pop();
+  const slug = base.replace(/\.use-case\.ts$/, "");
+  return slug.split("-").map((part, i) => i === 0 ? part : part[0].toUpperCase() + part.slice(1)).join("");
+}
diff --git a/packages/core-eslint/rules/_usecase-name.test.js b/packages/core-eslint/rules/_usecase-name.test.js
new file mode 100644
index 0000000..3cfcc63
--- /dev/null
+++ b/packages/core-eslint/rules/_usecase-name.test.js
@@ -0,0 +1,19 @@
+import { describe, it, expect } from "vitest";
+import { useCaseNameFromFile } from "./_usecase-name.js";
+
+describe("useCaseNameFromFile", () => {
+  it("converts kebab-case slug to camelCase", () => {
+    expect(useCaseNameFromFile("/repo/packages/auth/src/application/use-cases/sign-in.use-case.ts")).toBe("signIn");
+    expect(useCaseNameFromFile("/repo/packages/auth/src/application/use-cases/sign-up.use-case.ts")).toBe("signUp");
+    expect(useCaseNameFromFile("/repo/packages/blog/src/application/use-cases/get-article-by-slug.use-case.ts")).toBe("getArticleBySlug");
+  });
+
+  it("handles single-word slugs", () => {
+    expect(useCaseNameFromFile("/repo/packages/x/src/application/use-cases/login.use-case.ts")).toBe("login");
+  });
+
+  it("returns null for non-use-case files", () => {
+    expect(useCaseNameFromFile("/repo/packages/auth/src/index.ts")).toBeNull();
+    expect(useCaseNameFromFile("/repo/packages/auth/src/feature.manifest.ts")).toBeNull();
+  });
+});