@overeng/tui-react: support --output md

Context

Some CLIs built on @overeng/tui-react already support output selection via --output ..., but there is no built-in markdown mode.

For agent and automation workflows, --output md would be useful as a first-class final-render format: readable by humans, easy to paste into GitHub / Discord / docs, and more structured than plain text while staying simpler than JSON.

Current behavior

tui-react supports existing output modes such as json, ndjson, and pipe, but not markdown.

That means CLIs that want markdown output currently need to:

• implement custom post-processing themselves, or
• render text that only approximates markdown, or
• force consumers to convert from JSON / plain text afterward.

Desired behavior

Add support for:

--output md

with a documented contract for markdown output.

A good initial shape would be:

• final-output only (not streaming by default)
• optimized for copy/paste into GitHub issues, PR comments, Discord, docs, and agent handoffs
• deterministic enough that CLIs can rely on it for automation

Depending on the architecture, this could be either:

• a shared markdown renderer / output mode in @overeng/tui-react, or
• a standard interface that apps can implement so md is consistently supported across CLIs.

Why this is useful

Markdown is a strong middle ground between machine and human output:

• easier to read than JSON
• more structured than plain text
• portable across tools Johannes uses heavily (GitHub, Discord, docs, notes)
• especially useful for agent workflows where the result is often meant for both humans and further processing

Workaround

Current workaround is command-specific manual formatting after the fact, or using another output mode and converting it externally.

Filed by an AI assistant on behalf of @schickling

Start by locating the @overeng/tui-react output-mode implementation and reviewing how json, ndjson, and pipe are rendered. Define and document the deterministic final-output contract for --output md, then verify that a CLI can select it and that the result is suitable for the listed copy-and-paste workflows.