@supawatch/target-erd

The ER-diagram target for supawatch. Emits schema.erd.md: a Mermaid erDiagram inside a fenced block that GitHub renders natively, with PK and FK markers and relationship edges built from real foreign keys. Regenerated on every schema change, so the diagram stays correct instead of correct-once.

Configure it in supawatch.config.ts (the CLI loads this package by name):

targets: [{ kind: "erd" }]
// or, explicitly:
targets: [{ kind: "erd", attributes: "keys", maxTextSize: 50000 }]

A nullable foreign key renders as an optional relationship. Views appear as entities alongside tables. Database identifiers are free-form while Mermaid accepts only word-safe tokens, so entities carry a safe identifier plus the real name as a quoted display alias, and sanitized column names keep the original in the attribute comment.

Large schemas

Two Mermaid behaviors make big schemas render badly, and this target works around both by default, stating in a note whenever it trimmed something.

Mermaid refuses to render a diagram whose source passes maxTextSize (its own default is 50000 characters) and shows "Maximum text size in diagram exceeded" instead. So the target emits every column when that fits, otherwise key columns only, otherwise relationships only. Set attributes ("all" | "keys" | "none") to choose explicitly, and maxTextSize to match a renderer configured with a larger limit.

Mermaid also lays entities that have no relationships out in a single endless row, which stretches the canvas into an unreadable strip. Past maxIsolated (default 10) those tables are omitted and counted, and past maxEntities (default 60) the least connected go too. Every relationship between the entities that remain is always drawn. Set either to 0 to disable that cap.

MIT.