## Why
Flowcharts with `<br>` tags in node labels previously fell back to source instead of rendering as terminal diagrams.
## What changed
Render `<br>`, `<br/>`, and `<br />` as line breaks in quoted and unquoted flowchart node labels. Apply the 40-display-cell label limit per line and keep the decision marker on the first line. Continue rejecting other HTML, break tags in edge labels, and labels containing only breaks or whitespace.
## Testing
Extend rendering snapshots across all four flowchart directions and cover per-line width limits and unsupported markup. Update TUI streaming tests to cover multiline rendering, resizing, source fallback, and preservation of the original source for copying.
GitOrigin-RevId: 61f2a84c8bb161ac4a1c26ddaa0569f52bfea749
## Why
Flowcharts containing stadium nodes such as `A([Start])` currently fall back to source text instead of rendering in the TUI.
## What changed
Parse stadium declarations and render them with rounded box corners in every supported flowchart direction. Track node shapes explicitly so repeated declarations must agree on both label and shape. Document the supported `([label])` syntax.
## Testing
Add parser and snapshot coverage for repeated references, conflicting declarations, malformed syntax, Unicode labels, mixed shapes, and width limits across all four directions. Add a TUI snapshot for a stadium flowchart and verify source fallback when the diagram is too wide or malformed.
GitOrigin-RevId: 5ebd8babfd25ab4429b3e6c408cb7be8d7f1bb8e
## What changed
- Render completed `mermaid` fences with `codex-mermaid`, using syntax-theme colors for nodes and edges.
- Keep source visible for unclosed, invalid, unsupported, or oversized diagrams, and preserve the original Mermaid for copying and raw mode.
- Keep streamed diagrams mutable until the next top-level block so closing fences and terminal resizing can update their display. Preserve scrollback progress across width and render-mode changes.
## Testing
Add renderer and streaming tests covering supported diagram families, nested fences, Unicode, theme colors, source fallbacks, resizing, raw-mode transitions, and original-source preservation. Verify that node connection ports retain node styling in all four flowchart directions.
GitOrigin-RevId: 9a759248110e6730d629d653061ff7e2ec5dc2c0
## What changed
Add `codex-mermaid`, a standalone crate that renders supported subsets of flowchart, sequence, state, class, and ER diagrams as Unicode text. Expose `render` for plain text and `render_spans` for semantic node, edge, and text spans that callers can style.
Enforce source, diagram, canvas, and display-width limits. Return errors for unsupported input or exceeded limits without producing partial diagrams, leaving source fallback to callers. Include documentation and a stdin rendering example.
## Testing
Add snapshots for each diagram family, checks for relationship endpoints, Unicode labels, semantic spans, truncated input, and size limits, plus edge reconstruction for all 512 directed three-node graphs in all four layout directions.
GitOrigin-RevId: 5b4e65d9152abce5d833e4e6b12113a5a21f700e
Eric Traut