Reasoning
Surface the agent's thinking chain in the chat — default or fully custom.
This feature (agentic-chat-reasoning) hasn't been tagged in any Langroid cell yet. Try LangGraph (Python) instead, or browse the framework-agnostic version.
What is this?
Some models (OpenAI's o1, o3, and o4-mini, Anthropic's thinking
variants) emit reasoning tokens — internal chain-of-thought traces that
explain how the model is working toward its answer. CopilotKit surfaces
these as first-class messages: when a REASONING_MESSAGE_* event arrives
from the agent, the chat renders it inline so the user can follow the
agent's thinking.
Reasoning isn't a custom-renderer plumb-in — it's a dedicated message type
on the chat view. You can either accept the built-in rendering or override
the reasoningMessage slot with your own component.
When should I use this?
Expose reasoning in the UI when you want to:
- Give users real-time insight into the agent's thought process
- Show progress on long or multi-step problems
- Debug prompt behavior during development
- Brand the reasoning card to match the rest of your product
Default reasoning rendering (zero-config)
Out of the box, reasoning events render inside CopilotKit's built-in
CopilotChatReasoningMessage card:
- A "Thinking…" label with a pulsing indicator while the model reasons.
- Auto-expanded content so users can follow the chain of thought live.
- Collapses to "Thought for X seconds" once reasoning finishes, with a chevron to re-expand.
- Reasoning text rendered as Markdown.
No configuration is needed — if your model emits reasoning tokens, the card appears automatically:
langroid::reasoning-default-render. Known demos are bundled from manifest demos[i]; check the cell id and framework slug.Custom reasoning rendering
For full control over the reasoning card, pass a component to the
reasoningMessage slot on messageView. Your component receives the
ReasoningMessage object (.content holds the streaming text), the full
messages list, and isRunning — enough to decide whether this block is
still streaming and whether it's the active trailing message:
langroid::agentic-chat-reasoning. Known demos are bundled from manifest demos[i]; check the cell id and framework slug.The showcase's ReasoningBlock (imported above) renders the reasoning as
an amber-tagged inline banner — intentionally louder than the default card
so the thinking chain is the focal UI of the demo. Swap in your own
component to match your product's tone.
The messageView.reasoningMessage slot accepts either a full component
(as shown) or a sub-slot object like
{ header, contentView, toggle } if you just want to tweak parts of the
default card. See the reference docs for sub-slot props.