fix(core): suppress stale WORKFLOW_VERCEL_* env var warning outside serverless runtime (vercel#1345)

The warning about WORKFLOW_VERCEL_* env vars having no effect at runtime
was incorrectly shown when the Workflow CLI or web observability app was
running. These tools intentionally set those env vars. Gate the warning
on VERCEL=1 so it only fires inside Vercel serverless functions where the
env vars are truly unnecessary.

Author: TooTallNate

.changeset/funny-doors-allow.md

@@ -0,0 +1,5 @@
+---
+"@workflow/core": patch
+---
+
+Suppress stale `WORKFLOW_VERCEL_*` env var warning when running outside Vercel serverless (e.g. CLI, web observability app)

packages/core/src/runtime/world.ts

@@ -34,16 +34,18 @@ export const createWorld = (): World => {
   const targetWorld = resolveWorkflowTargetWorld();
 
   if (isVercelWorldTarget(targetWorld)) {
-    // Warn if WORKFLOW_VERCEL_* env vars are set — they have no effect at
-    // runtime and likely indicate a misconfiguration (user manually added
-    // them as Vercel project env vars, which is not needed).
+    // Warn if WORKFLOW_VERCEL_* env vars are set inside a Vercel serverless
+    // function (VERCEL=1) — they have no effect at runtime and likely indicate
+    // a misconfiguration (user manually added them as Vercel project env vars,
+    // which is not needed). We gate on VERCEL=1 so the warning does not fire
+    // when the CLI or web observability app sets these env vars intentionally.
     const staleEnvVars = [
       'WORKFLOW_VERCEL_PROJECT',
       'WORKFLOW_VERCEL_TEAM',
       'WORKFLOW_VERCEL_AUTH_TOKEN',
       'WORKFLOW_VERCEL_ENV',
     ].filter((key) => process.env[key]);
-    if (staleEnvVars.length > 0) {
+    if (staleEnvVars.length > 0 && process.env.VERCEL === '1') {
       console.warn(
         `[workflow] Warning: ${staleEnvVars.join(', ')} env var(s) ` +
           'are set but have no effect at runtime. These are only used by the Workflow CLI. ' +