diff --git a/packages/gittensory-engine/README.md b/packages/gittensory-engine/README.md
index 363f8d1a10..a4124aeb0c 100644
--- a/packages/gittensory-engine/README.md
+++ b/packages/gittensory-engine/README.md
@@ -11,6 +11,11 @@ The logic is extracted from the app's `src/` in follow-up issues; this skeleton
 the meantime. The root `package.json` already globs `packages/*` in its `workspaces` field, so `npm ci`
 discovers this package with no additional wiring.
 
+## Version pin
+
+`ENGINE_VERSION` mirrors `package.json`'s `version` field and is exported from the package barrel so consumers can
+log or assert which engine build produced a deterministic result.
+
 ## Build
 
 ```
diff --git a/packages/gittensory-engine/src/index.ts b/packages/gittensory-engine/src/index.ts
index 3fe4e1f595..5d52e13836 100644
--- a/packages/gittensory-engine/src/index.ts
+++ b/packages/gittensory-engine/src/index.ts
@@ -4,6 +4,7 @@
 // backend and the gittensory-miner (scoring preview/model, predicted-gate types, reward-risk, slop signals,
 // focus-manifest parse/compile core, duplicate-winner adjudication, and their engine-parity fixtures).
 // More modules land in follow-up issues.
+export { ENGINE_VERSION } from "./version.js";
 export {
   pickTopRankedOpportunities,
   rankOpportunityScore,
diff --git a/packages/gittensory-engine/src/version.ts b/packages/gittensory-engine/src/version.ts
new file mode 100644
index 0000000000..be6f0b62b7
--- /dev/null
+++ b/packages/gittensory-engine/src/version.ts
@@ -0,0 +1,5 @@
+/**
+ * Published semver of `@jsonbored/gittensory-engine`. Keep in lockstep with `package.json` `version`
+ * (enforced by `test/unit/engine-version.test.ts`).
+ */
+export const ENGINE_VERSION = "0.1.0";
diff --git a/test/unit/engine-version.test.ts b/test/unit/engine-version.test.ts
new file mode 100644
index 0000000000..43f9381b3f
--- /dev/null
+++ b/test/unit/engine-version.test.ts
@@ -0,0 +1,21 @@
+import { readFileSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+import { ENGINE_VERSION } from "../../packages/gittensory-engine/src/version";
+
+const pkgPath = join(dirname(fileURLToPath(import.meta.url)), "../../packages/gittensory-engine/package.json");
+
+describe("ENGINE_VERSION", () => {
+  it("matches packages/gittensory-engine/package.json version", () => {
+    const pkg = JSON.parse(readFileSync(pkgPath, "utf8")) as { version: string };
+    expect(ENGINE_VERSION).toBe(pkg.version);
+  });
+
+  it("is exported from the package barrel", async () => {
+    const barrel = await import("../../packages/gittensory-engine/src/index");
+    expect(barrel.ENGINE_VERSION).toBe(ENGINE_VERSION);
+    expect(barrel.ENGINE_VERSION.length).toBeGreaterThan(0);
+  });
+});