Ensemble diagrams — cheat sheet

One statement per line. Quote labels. Refer to ids, not to the words inside the quotes.

title Login flow
direction down

node start "Start" shape circle
node form "Enter login" shape parallelogram
node check "Valid?" shape diamond
node home "Dashboard" shape rounded color green
node db "Users DB" shape cylinder

edge start > form
edge form > check
edge check > home : "yes"
edge form -- db : "lookup"

title NAME
direction down|up|left|right
curve straight|curved|elbow

node ID "Label" shape SHAPE [color COLOR] [locked] [font PX] [bold] [italic] [underline]
edge ID > ID [: "label"] [curve straight|curved|elbow] [width PX] [head PX] [bend PX] [font PX] [bold]
edge ID --> ID [: "label"]     dashed arrow
edge ID -- ID                  line, no arrow
edge ID .. ID                  dashed line
edge ID <> ID                  arrows both ends
edge ID < ID                   arrow into the first id
edge FROM.e > TO.w             ports: n ne e se s sw w nw

group ID "Label" {
  node ...
}

text ID "Words you can drag" [font PX] [bold] [italic] [underline]

layout
  ID x y width height [locked]

Shapes: rectangle rounded diamond circle ellipse cylinder server triangle parallelogram document cloud actor hexagon note trapezoid queue subroutine browser delay.

Useful aliases: db = cylinder, decision = diamond, doc = document, person = actor, io = parallelogram, box = rectangle, kafka = queue, web = browser, wait = delay.

Two blocks have one line between them. A second line between the same two blocks is merged into the first (a reversed one makes it two-way, <>). Text sizes are 8–48 px; line width 0.5–8, head 6–40.

A bad line is skipped. A missing ) or : is kept, with a warning. An unknown shape becomes a rectangle. A name used only on an arrow becomes a rectangle, so declare blocks first.

A text that starts with flowchart or graph is read as Mermaid and then saved as the statements above.

Leave layout out of anything you write from scratch. The editor fills it in when someone moves a block or presses Reorganize. Reorganize lays each group out as its own frame, clear of the others. locked keeps that position on Reorganize, Fit vertically, and Fit horizontally.

curve defaults to straight. Set it once for the diagram, and again on a line only when that line should differ. elbow turns at right angles. Fit vertically writes direction down. Fit horizontally writes direction right.

Leave color off for the shape's own soft fill (blue for a step, amber for a decision, green for a start, teal for a database, and so on). color red or color "#336699" overrides it. The same name is lighter on a light canvas and deeper on a dark one.

Full rules and examples: docs/21_BLOCK_DIAGRAMS_DSL.md.