fix: extract and serialize JSON Schema from AI SDK v6 tools correctly

THE BREAKTHROUGH: AI SDK v6 tools use jsonSchema() which wraps plain JSON Schema objects, NOT Zod schemas. JSON Schema is fully serializable.

Changes:
1. Railway server: Extract raw JSON Schema from toolModule.inputSchema?.schema
2. Playground loader: Wrap received JSON Schema with { type: 'json_schema', schema: ... }
3. This matches AI SDK v6 format exactly - no Zod serialization needed

How it works:
- Tools define inputSchema: jsonSchema({ type: 'object', properties: {...} })
- AI SDK stores it as { type: 'json_schema', schema: {...} }
- Railway extracts the plain JSON Schema (.schema property)
- Sends it as plain JSON (fully serializable)
- Playground wraps it back in AI SDK format
- OpenAI receives valid JSON Schema for function calling

This fixes both errors:
✅ No more "def.shape is not a function" (not using Zod)
✅ No more "Invalid schema type None" (proper JSON Schema provided)

Note: Tools using Zod instead of jsonSchema() will need to migrate.
TPMJS standard: All tools MUST use jsonSchema() with plain JSON Schema.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/playground/src/lib/dynamic-tool-loader.ts

@@ -67,10 +67,12 @@ export async function loadToolDynamically(
     console.log(`📋 Description: ${data.tool.description}`);
 
     // Create a tool wrapper that executes remotely
-    // Note: We don't include inputSchema because Zod schemas can't be serialized over HTTP
-    // The AI SDK will infer parameters from the description
+    // Railway returns plain JSON Schema - wrap it in the AI SDK jsonSchema format
     const tool = {
       description: data.tool.description,
+      inputSchema: data.tool.inputSchema
+        ? { type: 'json_schema' as const, schema: data.tool.inputSchema }
+        : undefined,
       // biome-ignore lint/suspicious/noExplicitAny: Tool params are dynamic
       execute: async (params: any) => {
         console.log(`🚀 Executing ${packageName}/${exportName} remotely with params:`, params);

apps/railway-executor/server.ts

@@ -76,15 +76,16 @@ async function loadAndDescribe(req: Request): Promise<Response> {
     }
 
     // Extract tool definition
-    // Note: We don't send inputSchema because Zod schemas can't be serialized over JSON
-    // The playground will use the actual tool's inputSchema when creating the wrapper
+    // AI SDK v6 tools use jsonSchema() which wraps a plain JSON Schema object
+    // Extract the raw JSON Schema from toolModule.inputSchema.schema
+    const rawJsonSchema = toolModule.inputSchema?.schema ?? null;
+
     return Response.json({
       success: true,
       tool: {
         exportName,
         description: toolModule.description,
-        // Store reference that inputSchema exists (for validation)
-        hasInputSchema: !!toolModule.inputSchema,
+        inputSchema: rawJsonSchema, // Plain JSON Schema - fully serializable
       },
     });
   } catch (error) {