* feat: add trace-level input/output to Langfuse observability
- Add @langfuse/client and @langfuse/tracing dependencies
- Wrap POST handler with observe() for proper tracing
- Use updateActiveTrace() to set trace input, output, sessionId, userId
- Filter Next.js HTTP spans in shouldExportSpan so AI SDK spans become root traces
- Enable recordInputs/recordOutputs in experimental_telemetry
* refactor: extract Langfuse logic to separate lib/langfuse.ts module
- Switch from Geist to Plus Jakarta Sans (body) and JetBrains Mono (code)
- Add visual diff display for edit_diagram tool showing search/replace pairs
- Update color palette to clean modern OKLCH-based scheme
- Improve chat message display with better styling and animations
- Add syntax-highlighted code blocks for XML/JSON output
- Improve scrollbar and shadow utilities
- Install @ai-sdk/deepseek package
- Add DeepSeek provider support to lib/ai-providers.ts
- Add DeepSeek configuration to env.example
- Update README.md with DeepSeek in provider list
- Support both default and custom base URL for DeepSeek
* fix: correct anthropic beta header config for fine-grained tool streaming
- Use bedrock.anthropicBeta for Bedrock provider (not additionalModelRequestFields)
- Use top-level headers for direct Anthropic API
- Update @ai-sdk/amazon-bedrock to 3.0.62
- Add headers support to ModelConfig interface
* fix: update @ai-sdk/amazon-bedrock to 3.0.62 for tool streaming support
- Add OpenRouter provider support with @openrouter/ai-sdk-provider
- Fix input not disabling during 'submitted' state for fast providers
- Apply disable logic to all interactive elements (textarea, buttons, handlers)
- Clean up env.example by removing model examples and separator blocks
- Upgrade zod to v4.1.12 for compatibility with ollama-ai-provider-v2
- Add debug logging for status changes in chat components
- Integrate `xml_guide.md` into the system prompt to improve diagram generation by providing detailed XML formatting rules.
- Change the default AI model for chat completions to `openai("gpt-4.1")`.
- Update AI SDK packages (`@ai-sdk/amazon-bedrock`, `@ai-sdk/google`, `ai`) and other dependencies.
- Add `bun.lock` to the repository.
