fix(playground): address PR review findings

1. High: Fix SSR crash — move window.history.replaceState out of
   createResource fetcher into a client-only createEffect with
   isServer guard and useNavigate for URL updates.

2. Medium: Remove auth check from /update endpoint — the session
   UUID is the capability token. Both browser editor and MCP worker
   can update. Only /create requires PLAYGROUND_SECRET.

3. Medium: Add uniforms array to create_playground tool schema in
   both TOOLS and TOOLS_MCP_FORMAT so schema-driven MCP clients
   expose the parameter correctly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: devallibus

apps/web/src/routes/api/playground/$.ts

@@ -138,8 +138,9 @@ async function handlePlayground(request: Request): Promise<Response> {
   }
 
   // POST /api/playground/:sessionId/update
+  // No auth required — the session UUID is the capability token.
+  // Both the browser editor and the MCP worker can update.
   if (action === 'update' && request.method === 'POST') {
-    if (!isAuthorized(request)) return unauthorizedResponse()
     const session = getSession(sessionId)
     if (!session) return jsonResponse({ error: 'Session not found' }, 404)
 

apps/web/src/routes/playground.tsx

@@ -1,6 +1,7 @@
-import { createFileRoute, useSearch } from '@tanstack/solid-router'
+import { createFileRoute, useNavigate, useSearch } from '@tanstack/solid-router'
 import { createServerFn } from '@tanstack/solid-start'
-import { createResource, Show, Suspense } from 'solid-js'
+import { createEffect, createResource, on, Show, Suspense } from 'solid-js'
+import { isServer } from 'solid-js/web'
 import PlaygroundLayout from '../components/playground/PlaygroundLayout'
 import type { PlaygroundSession } from '../lib/playground-types'
 
@@ -28,21 +29,30 @@ export const Route = createFileRoute('/playground')({
 
 function PlaygroundPage() {
   const search = useSearch({ from: '/playground' })
+  const navigate = useNavigate()
 
   const [session] = createResource(
     () => search.session,
     async (sessionId) => {
       const result = await getOrCreateSession({ data: { sessionId } })
-      // Update URL with session ID if we created a new one
-      if (!sessionId && result?.id) {
-        const url = new URL(window.location.href)
-        url.searchParams.set('session', result.id)
-        window.history.replaceState({}, '', url.toString())
-      }
       return result as PlaygroundSession
     },
   )
 
+  // Update URL with session ID after hydration (client-only)
+  createEffect(
+    on(
+      () => session(),
+      (s) => {
+        if (isServer || !s) return
+        if (!search.session) {
+          navigate({ search: { session: s.id }, replace: true })
+        }
+      },
+      { defer: true },
+    ),
+  )
+
   return (
     <Suspense
       fallback={

packages/mcp/src/index.ts

@@ -117,6 +117,22 @@ const TOOLS = [
       properties: {
         vertexSource: { type: "string", description: "Initial vertex shader GLSL source." },
         fragmentSource: { type: "string", description: "Initial fragment shader GLSL source." },
+        uniforms: {
+          type: "array",
+          items: {
+            type: "object",
+            properties: {
+              name: { type: "string" },
+              type: { type: "string" },
+              defaultValue: {},
+              description: { type: "string" },
+              min: { type: "number" },
+              max: { type: "number" },
+            },
+            required: ["name", "type", "defaultValue"],
+          },
+          description: "Uniform definitions for the shader.",
+        },
         pipeline: { type: "string", description: "Rendering pipeline: 'surface', 'postprocessing', or 'geometry'." },
       },
       additionalProperties: false,
@@ -250,6 +266,22 @@ const TOOLS_MCP_FORMAT = [
           type: "string",
           description: "Initial fragment shader GLSL source (defaults to an animated color gradient)",
         },
+        uniforms: {
+          type: "array",
+          items: {
+            type: "object",
+            properties: {
+              name: { type: "string" },
+              type: { type: "string" },
+              defaultValue: {},
+              description: { type: "string" },
+              min: { type: "number" },
+              max: { type: "number" },
+            },
+            required: ["name", "type", "defaultValue"],
+          },
+          description: "Uniform definitions (name, type, defaultValue, optional min/max/description)",
+        },
         pipeline: {
           type: "string",
           description: "Rendering pipeline: 'surface' (default), 'postprocessing', or 'geometry'",