feat: add auto_collapse parameter to Step

[Br1an67]

What

Add auto_collapse parameter to Step that automatically collapses the step accordion when it finishes.

Closes #2081

Why

Long tool steps stream lots of tokens. After completion, developers want to signal "done" and reduce UI clutter by collapsing the step automatically.

Changes

• backend/chainlit/step.py: Add auto_collapse: Optional[bool] = False to StepDict and Step class, include in to_dict()
• libs/react-client/src/types/step.ts: Add autoCollapse?: boolean to IStep
• frontend/src/components/chat/Messages/Message/Step.tsx: Switch accordion from uncontrolled to controlled mode, auto-collapse via useEffect when step finishes and autoCollapse is set

Usage

async with cl.Step(name="web_search", default_open=True, auto_collapse=True) as step:
    step.output = "Searching..."
    await step.update()
    # ... do work ...
    step.output = result
# Step auto-collapses when context exits

Testing

• Steps without auto_collapse behave identically (backward compatible)
• Accordion remains user-interactive: users can expand/collapse after auto-collapse
• defaultOpen still respected for initial state

---

Summary by cubic

Add auto-collapse to steps so finished steps automatically fold to reduce UI clutter. Keeps manual control and default open behavior; step() decorator now forwards the flag; no breaking changes.

• New Features
  • Added auto_collapse (Python) / autoCollapse (TS) to Step, serialization, and step() decorator forwarding.
  • Switched the step accordion to controlled mode and collapse on finish when autoCollapse is true.
  • Backward compatible: defaultOpen still sets initial state, and users can toggle after auto-collapse.

^{Written for commit a1158f3. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="backend/chainlit/step.py">

<violation number="1" location="backend/chainlit/step.py:203">
P2: auto_collapse is added to Step but the step() decorator does not accept or forward it, so decorated steps cannot opt into auto-collapse.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}