chore: import upstream snapshot with attribution

apps/sim/app/llms.txt/route.ts

@@ -0,0 +1,68 @@
+import { getBaseUrl } from '@/lib/core/utils/urls'
+
+export function GET() {
+  const baseUrl = getBaseUrl()
+
+  const content = `# Sim
+
+> Sim is the open-source AI workspace where teams build, deploy, and manage AI agents. Connect 1,000+ integrations and every major LLM to create agents that automate real work.
+
+Sim lets teams create agents visually with the workflow builder, conversationally through Chat, or programmatically with the API. The workspace includes knowledge bases, tables, files, and full observability.
+
+## Preferred URLs
+
+- [Homepage](${baseUrl}): Product overview and primary entry point
+- [Integrations directory](${baseUrl}/integrations): Public catalog of integrations and automation capabilities
+- [Models directory](${baseUrl}/models): Public catalog of AI models, pricing, context windows, and capabilities
+- [Blog](${baseUrl}/blog): Announcements, guides, and product context
+- [Changelog](${baseUrl}/changelog): Product updates and release notes
+
+## Documentation
+
+- [Documentation](https://docs.sim.ai): Product guides and technical reference
+- [Quickstart](https://docs.sim.ai/getting-started): Fastest path to getting started
+- [API Reference](https://docs.sim.ai/api-reference): API documentation
+
+## Key Concepts
+
+- **Workspace**: The AI workspace — container for agents, workflows, data sources, and runs
+- **Workflow**: Visual builder — directed graph of blocks defining agent logic
+- **Block**: Individual step such as an LLM call, tool call, HTTP request, or code execution
+- **Trigger**: Event or schedule that initiates a workflow run
+- **Execution**: A single run of a workflow with logs and outputs
+- **Knowledge Base**: Document store used for retrieval-augmented generation
+
+## Capabilities
+
+- AI workspace for teams
+- AI agent creation and deployment
+- Integrations across business tools, databases, and communication platforms
+- Multi-model LLM orchestration
+- Knowledge bases and retrieval-augmented generation
+- Table creation and management
+- Document creation and processing
+- Scheduled and webhook-triggered runs
+
+## Use Cases
+
+- AI agent deployment and orchestration
+- Knowledge bases and RAG pipelines
+- Customer support automation
+- Internal operations workflows across sales, marketing, legal, and finance
+
+## Additional Links
+
+- [GitHub Repository](https://github.com/simstudioai/sim): Open-source codebase
+- [Docs](https://docs.sim.ai): Canonical documentation source
+- [Terms of Service](${baseUrl}/terms): Legal terms
+- [Privacy Policy](${baseUrl}/privacy): Data handling practices
+- [Sitemap](${baseUrl}/sitemap.xml): Public URL inventory
+`
+
+  return new Response(content, {
+    headers: {
+      'Content-Type': 'text/markdown; charset=utf-8',
+      'Cache-Control': 'public, max-age=86400, s-maxage=86400',
+    },
+  })
+}