fix(workflow-executor): guard selectedTool lookup and resolve related collection schema

- Replace non-null assertion with explicit McpToolNotFoundError when AI
  selects a tool name that doesn't match any available tool
- Resolve related collection name from parent schema before looking up
  the related schema in cache, fixing cases where relation name differs
  from target collection name

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: matthv

packages/workflow-executor/src/adapters/agent-client-agent-port.ts

@@ -89,7 +89,10 @@ export default class AgentClientAgentPort implements AgentPort {
     user: StepUser,
   ): Promise<RecordData[]> {
     const client = this.createClient(user);
-    const relatedSchema = this.resolveSchema(relation);
+    const parentSchema = this.resolveSchema(collection);
+    const relationField = parentSchema.fields.find(f => f.fieldName === relation);
+    const relatedCollectionName = relationField?.relatedCollectionName ?? relation;
+    const relatedSchema = this.resolveSchema(relatedCollectionName);
 
     const records = await client
       .collection(collection)

packages/workflow-executor/src/executors/mcp-step-executor.ts

@@ -58,7 +58,8 @@ export default class McpStepExecutor extends BaseStepExecutor<McpStepDefinition>
     const tools = this.getFilteredTools();
     const { toolName, args } = await this.selectTool(tools);
     const selectedTool = tools.find(t => t.base.name === toolName);
-    const target: McpToolCall = { name: toolName, sourceId: selectedTool!.sourceId, input: args };
+    if (!selectedTool) throw new McpToolNotFoundError(toolName);
+    const target: McpToolCall = { name: toolName, sourceId: selectedTool.sourceId, input: args };
 
     if (this.context.stepDefinition.automaticExecution) {
       // Branch B -- direct execution