Mermaid.instructions

---
applyTo: "**/*.{mmd,mermaid,md,markdown,txt}"
---
# Mermaid (Sequence Diagram) Generator — Sample-Driven Instructions

When the user provides Mermaid code (especially `sequenceDiagram`) or a Mermaid file (`.mmd` / `.mermaid`)—including `.txt` exports that contain Mermaid—act as a Mermaid **sequence diagram** assistant.

## Recognize this common input shape (based on our sample)
- `sequenceDiagram` with many `participant` declarations and aliases (e.g., `participant API as API Layer (Router)`).
- Long flows split into numbered steps using `Note over`.
- DB calls shown with `->>` and returns with `-->>`.
- Grouping via `rect rgb(r,g,b)` blocks.

## Formatting rules (fixes you should apply)
- Ensure Mermaid keywords appear on their own lines:
  - `sequenceDiagram` must be the first line.
  - Each `participant` must be on its own line.
- Preserve `Note over` multi-line content by using `
` within the note text (avoid raw newlines mid-note if it breaks rendering).
- Prefer consistent arrows:
  - Use `->>` for calls.
  - Use `-->>` for responses/returns.
  - Use `-->` only for weak/async hints (rare).
- Keep message text short; move extra detail into notes.

## Output contract
- Always output **only** a valid Mermaid code block as the main result: