chore: import upstream snapshot with attribution

tests/unit/db-case-mapping-split.test.ts

@@ -0,0 +1,70 @@
+// Characterization of the db/core.ts column-mapping split (god-file decomposition): the pure
+// snake_case ↔ camelCase row helpers moved into db/caseMapping.ts. Behavior-preserving move — these
+// locks pin the conversion semantics (boolean coercion for known flag columns, JSON parsing for
+// providerSpecificData + `_json` TEXT columns, null-stripping) and that core.ts still re-exports them
+// for the historical `from "./core"` import surface.
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+const M = await import("../../src/lib/db/caseMapping.ts");
+const CORE = await import("../../src/lib/db/core.ts");
+
+test("module exposes the five mapping helpers", () => {
+  for (const name of ["toSnakeCase", "toCamelCase", "objToSnake", "rowToCamel", "cleanNulls"]) {
+    assert.equal(typeof (M as Record<string, unknown>)[name], "function", `missing ${name}`);
+  }
+});
+
+test("core.ts re-exports the same helpers (historical surface preserved)", () => {
+  for (const name of ["toSnakeCase", "toCamelCase", "objToSnake", "rowToCamel", "cleanNulls"]) {
+    assert.equal((CORE as Record<string, unknown>)[name], (M as Record<string, unknown>)[name]);
+  }
+});
+
+test("toSnakeCase / toCamelCase round-trip column names", () => {
+  assert.equal(M.toSnakeCase("maxRequestsPerDay"), "max_requests_per_day");
+  assert.equal(M.toCamelCase("max_requests_per_day"), "maxRequestsPerDay");
+});
+
+test("objToSnake converts keys, passes non-objects through", () => {
+  assert.deepEqual(M.objToSnake({ providerId: "x", isActive: 1 }), {
+    provider_id: "x",
+    is_active: 1,
+  });
+  assert.equal(M.objToSnake(null), null);
+  assert.equal(M.objToSnake("str"), "str");
+});
+
+test("rowToCamel coerces known boolean flags from 0/1", () => {
+  const out = M.rowToCamel({ is_active: 1, proxy_enabled: 0, per_key_proxy_enabled: 1 });
+  assert.equal(out?.isActive, true);
+  assert.equal(out?.proxyEnabled, false);
+  assert.equal(out?.perKeyProxyEnabled, true);
+  assert.equal(M.rowToCamel(null), null);
+});
+
+test("rowToCamel parses providerSpecificData JSON string", () => {
+  const out = M.rowToCamel({ provider_specific_data: '{"a":1}' });
+  assert.deepEqual(out?.providerSpecificData, { a: 1 });
+  // invalid JSON falls back to the raw string
+  const bad = M.rowToCamel({ provider_specific_data: "not json" });
+  assert.equal(bad?.providerSpecificData, "not json");
+});
+
+test("rowToCamel unwraps `_json` columns to the base key", () => {
+  const out = M.rowToCamel({ quota_window_thresholds_json: '{"hi":80}' });
+  assert.deepEqual(out?.quotaWindowThresholds, { hi: 80 });
+  assert.equal("quotaWindowThresholdsJson" in (out ?? {}), false);
+  // NULL `_json` column normalizes the base key to null
+  const nul = M.rowToCamel({ quota_window_thresholds_json: null });
+  assert.equal(nul?.quotaWindowThresholds, null);
+});
+
+test("cleanNulls drops null/undefined, keeps falsy-but-present values", () => {
+  assert.deepEqual(M.cleanNulls({ a: 0, b: "", c: null, d: undefined, e: false }), {
+    a: 0,
+    b: "",
+    e: false,
+  });
+  assert.deepEqual(M.cleanNulls(null), {});
+});