diff --git a/tests/omp-path-contract.test.ts b/tests/omp-path-contract.test.ts
new file mode 100644
index 000000000..cc0e04fc5
--- /dev/null
+++ b/tests/omp-path-contract.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, test } from "bun:test";
+import { mkdtempSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { ompModelsConfigPath } from "../src/clients/config-export";
+
+function withTempHome(run: (home: string) => void): void {
+  const home = mkdtempSync(join(tmpdir(), "opencodex-omp-home-"));
+  try {
+    run(home);
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+}
+
+describe("OMP path contract regressions", () => {
+  test("PI_CONFIG_DIR remains home-relative for slash- and tilde-prefixed values", () => {
+    withTempHome(home => {
+      for (const value of ["/custom-omp", "~/.custom-omp"]) {
+        expect(ompModelsConfigPath({ PI_CONFIG_DIR: value } as NodeJS.ProcessEnv, home)).toBe(
+          join(home, value, "agent", "models.yml"),
+        );
+      }
+    });
+  });
+
+  test("a named profile ignores PI_CODING_AGENT_DIR", () => {
+    withTempHome(home => {
+      const configDir = "custom-omp";
+
+      expect(ompModelsConfigPath({
+        OMP_PROFILE: "work",
+        PI_CONFIG_DIR: configDir,
+        PI_CODING_AGENT_DIR: join(home, "wrong-agent"),
+      } as NodeJS.ProcessEnv, home)).toBe(
+        join(home, configDir, "profiles", "work", "agent", "models.yml"),
+      );
+    });
+  });
+});