diff --git a/package.json b/package.json
index 2d5812b..569186b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "workflow-observer",
-  "version": "0.9.5",
+  "version": "0.9.6",
   "private": false,
   "type": "module",
   "scripts": {
diff --git a/src/build.ts b/src/build.ts
index 0ae3ac1..4811de5 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -38,6 +38,8 @@ console.log(`Built server, CLI and ${files.length} browser assets.`);
 
 const pkg = await Bun.file(join(root, "package.json")).json();
 const hash = createHash("sha256");
+// A version-only release must not reuse an older runtime's package metadata.
+hash.update(JSON.stringify([pkg.name, pkg.version]));
 for (const file of ["cli.js", "server.js", ...files.sort().map((f) => "client" + f)])
   hash.update(
     await Bun.file(join(out, file))
diff --git a/tests/build-release.test.ts b/tests/build-release.test.ts
new file mode 100644
index 0000000..8abffaa
--- /dev/null
+++ b/tests/build-release.test.ts
@@ -0,0 +1,44 @@
+import { expect, test } from "bun:test";
+import { cp, mkdir, mkdtemp, rm } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { prepareRuntime, releaseInfo } from "../src/companion/install";
+
+test("version-only releases get distinct immutable runtime snapshots", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "observer-release-"));
+  const root = join(dir, "package");
+  try {
+    await mkdir(join(root, "src", "client"), { recursive: true });
+    await mkdir(join(root, "public"));
+    await cp(join(import.meta.dir, "../src/build.ts"), join(root, "src", "build.ts"));
+    for (const file of ["cli.ts", "server.ts", "client/main.tsx"])
+      await Bun.write(join(root, "src", file), 'console.log("same application");');
+    await Bun.write(join(root, "public", "index.html"), "<!doctype html><title>Observer</title>");
+    const build = async (version: string) => {
+      await Bun.write(
+        join(root, "package.json"),
+        JSON.stringify({ name: "workflow-observer", version }),
+      );
+      const child = Bun.spawn([process.execPath, "src/build.ts"], {
+        cwd: root,
+        stdout: "ignore",
+        stderr: "pipe",
+      });
+      const error = await new Response(child.stderr).text();
+      if ((await child.exited) !== 0) throw new Error(error);
+      return releaseInfo(root);
+    };
+    const before = await build("0.1.0");
+    const first = await prepareRuntime(root, join(dir, "data"));
+    const after = await build("0.1.1");
+    expect(after.build).not.toBe(before.build);
+    const second = await prepareRuntime(root, join(dir, "data"));
+    expect(second).not.toBe(first);
+    expect((await releaseInfo(first)).version).toBe("0.1.0");
+    expect((await releaseInfo(second)).version).toBe("0.1.1");
+    expect((await build("0.1.1")).build).toBe(after.build);
+    expect(await prepareRuntime(root, join(dir, "data"))).toBe(second);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});