From 49bd7e078215f19ba37b54e86a3247a79c12a50d Mon Sep 17 00:00:00 2001
From: Danijel Martinek <danijel@fraqtal.xyz>
Date: Tue, 12 May 2026 22:43:15 +0200
Subject: [PATCH] feat(core-shared/conformance): ConformanceError class

---
 .../src/conformance/conformance-error.test.ts   | 17 +++++++++++++++++
 .../src/conformance/conformance-error.ts        | 13 +++++++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 packages/core-shared/src/conformance/conformance-error.test.ts
 create mode 100644 packages/core-shared/src/conformance/conformance-error.ts

diff --git a/packages/core-shared/src/conformance/conformance-error.test.ts b/packages/core-shared/src/conformance/conformance-error.test.ts
new file mode 100644
index 0000000..4d4eb46
--- /dev/null
+++ b/packages/core-shared/src/conformance/conformance-error.test.ts
@@ -0,0 +1,17 @@
+import { describe, it, expect } from "vitest";
+import { ConformanceError } from "@/conformance/conformance-error";
+
+describe("ConformanceError", () => {
+  it("extends Error with the standard shape", () => {
+    const err = new ConformanceError("auth.signIn: missing __instrumented brand");
+    expect(err).toBeInstanceOf(Error);
+    expect(err).toBeInstanceOf(ConformanceError);
+    expect(err.message).toBe("auth.signIn: missing __instrumented brand");
+    expect(err.name).toBe("ConformanceError");
+  });
+
+  it("preserves a stack trace", () => {
+    const err = new ConformanceError("test");
+    expect(typeof err.stack).toBe("string");
+  });
+});
diff --git a/packages/core-shared/src/conformance/conformance-error.ts b/packages/core-shared/src/conformance/conformance-error.ts
new file mode 100644
index 0000000..4683262
--- /dev/null
+++ b/packages/core-shared/src/conformance/conformance-error.ts
@@ -0,0 +1,13 @@
+/**
+ * Thrown by `assertFeatureConformance` when a binding does not match the
+ * manifest's declared shape. The boot assertion lets this propagate
+ * synchronously so `pnpm dev` refuses to start on drift.
+ */
+export class ConformanceError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "ConformanceError";
+    // Maintain a proper prototype chain across down-compilation.
+    Object.setPrototypeOf(this, ConformanceError.prototype);
+  }
+}