fix: derive observability-cloud SDK_VERSION from package.json at build time

The hardcoded constant had already drifted (0.0.1 vs manifest 0.0.2), failing
the package's own version-match test — and changesets-automated bumps would
re-break it on every release. tsdown now injects the manifest version via
define, with vitest.config.ts mirroring it for tests; the existing test stays
as the guard.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: 2 people

.changeset/observability-cloud-sdk-version.md

@@ -0,0 +1,7 @@
+---
+"@openuidev/observability-cloud": patch
+---
+
+`SDK_VERSION` is now derived from package.json at build time instead of a
+hardcoded constant that had drifted (wire envelopes previously reported
+`0.0.1` regardless of the released version).

packages/observability-cloud/src/core/wire.ts

@@ -1,8 +1,10 @@
 import type { ObservabilityLevel } from "@openuidev/observability";
 import type { StreamWireEvent } from "../events/stream";
 
-/** Must be kept in sync with packages/observability-cloud/package.json on release. */
-export const SDK_VERSION = "0.0.1";
+declare const __SDK_VERSION__: string;
+
+/** Injected from package.json at build time (tsdown define; vitest.config.ts mirrors it for tests). */
+export const SDK_VERSION = __SDK_VERSION__;
 
 export interface WireEventBase {
   id: string;

packages/observability-cloud/tsdown.config.ts

@@ -1,7 +1,15 @@
+import { readFileSync } from "node:fs";
 import { defineConfig } from "tsdown";
 
+const { version } = JSON.parse(readFileSync(new URL("./package.json", import.meta.url), "utf8")) as {
+  version: string;
+};
+
 export default defineConfig({
   entry: ["src/index.ts"],
+  define: {
+    __SDK_VERSION__: JSON.stringify(version),
+  },
   format: ["esm", "cjs"],
   dts: true,
   sourcemap: true,

packages/observability-cloud/vitest.config.ts

@@ -0,0 +1,13 @@
+import { readFileSync } from "node:fs";
+import { defineConfig } from "vitest/config";
+
+const { version } = JSON.parse(readFileSync(new URL("./package.json", import.meta.url), "utf8")) as {
+  version: string;
+};
+
+export default defineConfig({
+  define: {
+    // Mirrors the tsdown define so src imports resolve SDK_VERSION in tests.
+    __SDK_VERSION__: JSON.stringify(version),
+  },
+});