diff --git a/package-lock.json b/package-lock.json
index f547cdc8..ee13047a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6378,7 +6378,6 @@
       "version": "2.3.2",
       "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
       "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
-      "dev": true,
       "hasInstallScript": true,
       "license": "MIT",
       "optional": true,
diff --git a/src/app/api/metrics/repo-health/route.ts b/src/app/api/metrics/repo-health/route.ts
index 5a8ee0f6..ba8bc8dc 100644
--- a/src/app/api/metrics/repo-health/route.ts
+++ b/src/app/api/metrics/repo-health/route.ts
@@ -76,7 +76,11 @@ export async function GET(req: NextRequest) {
         try {
           const signals = await fetchSignalsForRepo(session.accessToken!, repo.name, days);
           scores.push(computeHealthScore(repo.name, signals));
-        } catch {}
+        } catch (err) {
+          console.error(`Failed to fetch signals for repo ${repo}:`, err);
+          // Continue with remaining repos
+          continue;
+        }
       }
       return { repos: scores };
     });
diff --git a/test/resolve-user.test.ts b/test/resolve-user.test.ts
new file mode 100644
index 00000000..d279f84f
--- /dev/null
+++ b/test/resolve-user.test.ts
@@ -0,0 +1,98 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const fromMock = vi.fn();
+const supabaseAdmin = {
+  from: fromMock,
+};
+
+vi.mock("../src/lib/supabase", () => ({
+  supabaseAdmin,
+}));
+
+const { resolveAppUser } = await import("../src/lib/resolve-user");
+
+function createExistingChain(result: unknown) {
+  const single = vi.fn(async () => result);
+  const eq = vi.fn(() => ({ single }));
+  const select = vi.fn(() => ({ eq }));
+  return { select, eq, single };
+}
+
+function createUpsertChain(result: unknown) {
+  const single = vi.fn(async () => result);
+  const select = vi.fn(() => ({ single }));
+  const upsert = vi.fn(() => ({ select }));
+  return { upsert, select, single };
+}
+
+describe("resolveAppUser", () => {
+  beforeEach(() => {
+    fromMock.mockReset();
+  });
+
+  it("returns null when user not found and githubLogin is null", async () => {
+    const existingChain = createExistingChain({ data: null });
+    const upsertChain = createUpsertChain({ data: null });
+
+    fromMock
+      .mockImplementationOnce(() => existingChain)
+      .mockImplementationOnce(() => upsertChain);
+
+    const result = await resolveAppUser("github-id", null as unknown as string);
+
+    expect(result).toBeNull();
+    expect(fromMock).toHaveBeenCalledTimes(2);
+    expect(existingChain.select).toHaveBeenCalledWith("id");
+    expect(upsertChain.upsert).toHaveBeenCalledTimes(1);
+  });
+
+  it("upserts new user when githubLogin is provided", async () => {
+    const existingChain = createExistingChain({ data: null });
+    const upsertChain = createUpsertChain({ data: { id: "new-user-id" } });
+
+    fromMock
+      .mockImplementationOnce(() => existingChain)
+      .mockImplementationOnce(() => upsertChain);
+
+    const result = await resolveAppUser("github-id", "github-login");
+
+    expect(result).toEqual({ id: "new-user-id" });
+    expect(fromMock).toHaveBeenCalledTimes(2);
+    expect(existingChain.select).toHaveBeenCalledWith("id");
+    expect(upsertChain.upsert).toHaveBeenCalledTimes(1);
+
+    const upsertPayload = upsertChain.upsert.mock.calls[0][0];
+    expect(upsertPayload).toEqual(
+      expect.objectContaining({
+        github_id: "github-id",
+        github_login: "github-login",
+      })
+    );
+    expect(typeof upsertPayload.updated_at).toBe("string");
+  });
+
+  it("returns existing user data when found", async () => {
+    const existingChain = createExistingChain({ data: { id: "existing-id" } });
+
+    fromMock.mockImplementationOnce(() => existingChain);
+
+    const result = await resolveAppUser("github-id", "ignored-login");
+
+    expect(result).toEqual({ id: "existing-id" });
+    expect(fromMock).toHaveBeenCalledTimes(1);
+  });
+
+  it("handles database errors gracefully", async () => {
+    const existingChain = createExistingChain({ data: null, error: new Error("database failure") });
+    const upsertChain = createUpsertChain({ data: null, error: new Error("insert failure") });
+
+    fromMock
+      .mockImplementationOnce(() => existingChain)
+      .mockImplementationOnce(() => upsertChain);
+
+    const result = await resolveAppUser("github-id", "github-login");
+
+    expect(result).toBeNull();
+    expect(fromMock).toHaveBeenCalledTimes(2);
+  });
+});
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 00000000..5c0ab798
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,16 @@
+import { defineConfig } from "vitest/config";
+import { fileURLToPath } from "node:url";
+import { dirname, resolve } from "node:path";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+export default defineConfig({
+  resolve: {
+    alias: [
+      {
+        find: "@",
+        replacement: resolve(__dirname, "src"),
+      },
+    ],
+  },
+});