mermaid-helper

# mermaid-helper — draw the right diagram in mermaid ## Pick the right diagram type | Want to show | Use | |--------------|-----| | Box-and-arrow architecture | `flowchart TD` | | Who calls whom across time | `sequenceDiagram` | | Step-by-step process | `flowchart LR` | | Entity relationships (DB schema) | `erDiagram` | | State transitions | `stateDiagram-v2` | | Class structure | `classDiagram` | | Gantt / project timeline | `gantt` | | Pie chart of percentages | `pie title …` | | Git branch flow | `gitGraph` | If unsure, default to `flowchart TD` (top-down) for static structure and `sequenceDiagram` for temporal interactions. ## Common gotchas - **Spaces in node names** must be quoted: `A["Order Service"]`, not `A[Order Service]` (the latter works but breaks if the label has punctuation). - **HTML in labels** needs `&` escapes: `A & B` → `A & B`. - **Edge labels**: `A -->|publishes event| B`, the pipes are required. - **Subgraphs** need explicit `end`: `subgraph X\n A\n B\nend`. - **classDef** for styling: `classDef warn fill:#fee,stroke:#900;` then `class A,B warn;`. - **Sequence diagrams**: use `participant A as Alice` to give friendly names; use `Note over A: text` for inline annotations. ## Validation checklist (before returning) - [ ] Every opening `[` `(` `{` has a matching close - [ ] Every `subgraph` has a corresponding `end` - [ ] Arrow syntax is consistent (`-->`, `---`, `==>`, `-.->`) - [ ] Quoted labels for anything with spaces, parentheses,...