[FEATURE] Add preswald export --format markdown CLI Command for Generating Markdown Reports

[amrutha97]

Enable users to export the current Preswald app's rendered state into a well-formatted Markdown report via the CLI. This makes it easy to generate lightweight, version-controllable, and GitHub/GitLab-friendly snapshots of an app’s output.

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Motivation

Markdown exports are useful for:

• Creating reproducible, readable analysis logs
• Sharing results via GitHub, Notion, or static documentation sites
• Archiving outputs alongside source code
• Enhancing developer workflows with Markdown-based reporting

This feature simplifies app-to-doc workflows without requiring frontend interaction or custom tooling.

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Acceptance Criteria

• Add CLI command:

  preswald export --format markdown --output report.md

• Run app in headless mode (like preswald run, but silent)

• Capture the rendered state of all static and interactive components

• Generate a structured .md file that includes:

  • Markdown headers from text()
  • Data tables from table()
  • Inline callouts from alert()
  • Markdown-renderable forms of progress, checkbox, selectbox, etc.
  • Chart references or alt text from plotly() (optional PNG if --include-images is used)

• Default output path: exports/app.md if --output is not provided

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Implementation Plan

• Extend preswald/cli.py with export --format markdown
• Add MarkdownExporter class in preswald/utils/exporter.py
• Hook into component registry to collect component render calls (reuse internal service from run)
• Implement serialization logic for each supported component type
• Optional: Use Plotly's to_image() for embedding static PNGs of charts (if --include-images is enabled)

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Testing Plan

Run:

preswald run
preswald export --format markdown --output output/report.md

Validate:

• report.md is created and readable in VS Code / GitHub preview
• Markdown syntax is valid and renders cleanly
• Components show up in correct order, with all user-visible state

Example snapshot:

# My Dashboard

> ✅ Model Training Complete

## Accuracy Chart  
![Accuracy over time](charts/fig1.png)

## Config  
- Region: North America  
- Slider value: 70

## Data Preview  
| Name | Score |  
|------|-------|  
| Alice | 88.4 |  
| Bob   | 92.1 |

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Related Files

• preswald/cli.py
• preswald/service.py
• preswald/utils/exporter.py
• (optional) Add plotly[kaleido] to extras for chart export

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Extra

• --include-code to append the Python source file
• --include-images to embed static charts
• --format html for rich HTML export
• Add GitHub Action for CI-based report generation

[curious-companion]

Hey @amrutha97, hope you're doing well!

I noticed that cli.py already includes an export command supporting pdf and html formats.
I'm thinking of adding support for exporting in Markdown (.md) format as well.

Just wanted to confirm — would it be okay to add the Markdown export logic as an additional option under the existing export command using --format md?

Happy to take this up if it aligns with the project direction!