Flowchart values

moonrockz/diagrams/flowchart provides immutable flowchart models without a syntax reader, renderer, host adapter or UI dependency. Mermaid flowcharts and both PlantUML activity dialects convert to this model. Callers can also construct it directly. Constructors copy caller-owned mutable collections.

///|
test "construct an immutable flowchart with ordinary groups" {
  let nodes = [
    @flowchart.Node::new("Read", label="Read request", groups=["Work"]),
    @flowchart.Node::new("Save", label="Save", groups=["Work"]),
  ]
  let view = @flowchart.Flowchart::new(
    "request",
    nodes[:],
    [@flowchart.Connection::new("save", "Read", "Save")],
    direction=LR,
    groups=[@flowchart.Group::new("Work")],
    notes=[
      @flowchart.Note::new("Detail", "Source text", targets=["Read"], groups=[
        "Work",
      ]),
    ],
  )
  nodes[0] = @flowchart.Node::new("Changed")
  assert_eq(view.nodes[0].id, "Read")
  assert_eq(view.lanes.length(), 0)
  assert_eq(view.groups[0].id, "Work")
  assert_eq(view.connections[0].source, "Read")
  assert_eq(@flowchart.validate(view), [])
}

Nodes keep stable IDs, label kinds, vector shape identity, metadata, group paths, explicit lane ownership, typed roles, region membership and source bindings. Shape identity and control role are separate. A generic Mermaid diamond remains Generic; PlantUML conversion can supply Decision, Merge, Fork, Join, Start, ActivityFinal, FlowFinal, Connector or Action explicitly.

Connections retain IDs, declared source/target, labels, line style, markers at both ends, length/direction hints, typed role and origin. Equal labels never merge separate occurrences. Global TB, BT, LR and RL affect placement without reversing stored endpoints. Source conversion accepts TD as TB.

///|
test "control role and source identity are explicit values" {
  let origin = @flowchart.SourceBinding::new("caller", "actions/0")
  let action = @flowchart.Node::new("Review", role=Action, origin~)
  let view = @flowchart.Flowchart::new("review", [action], [])
  assert_eq(view.nodes[0].role, Action)
  assert_eq(view.nodes[0].origin.unwrap().path, "actions/0")
  assert_eq(view.nodes[0].origin.unwrap().span, None)
  assert_eq(@flowchart.validate(view), [])
  assert_true(!@flowchart.validate(view, work_limit=1).is_empty())
}

Groups retain their parent, label, optional local direction and expanded state. Ordinary subgraphs stay groups. Lanes represent explicit responsibility declarations and keep declared order. A PlantUML partition can span lane changes without changing a node's semantic group path. Notes retain node and connection attachments, text, placement and ownership. Note attachments are descriptive and never become control-flow route edges.

Structured regions retain ordered branch and loop/parallel membership, conditions, entry/exit references and join specifications. These values describe source structure. The model never evaluates conditions, executes actions or implements token or synchronization semantics.

validate uses explicit node, edge, depth and work limits. It reports duplicate identities, missing endpoints/note targets, ownership cycles, invalid group paths and inconsistent region references without repairing them. Source bindings use the shared half-open UTF-16 span contract when a source position exists. Construction, validation and transformations are deterministic on wasm, wasm-gc, js and native.

Pass Diagram::Flowchart(view) to the shared SVG or animated renderer. Geometry, scene bindings, finite plans, structural routes and reachability are separate packages. See flowcharts and animation and run mise run test:flowchart-consumer for fresh model-only, native-reader and SVG/player consumers on all four targets.