Mermaid flowcharts

Read Mermaid flowchart, graph and flowchart-elk source through moonrockz/diagrams-mermaid. Compatibility follows the pinned Mermaid 12.2.0 grammar and database semantics. Source processing and SVG output work without upstream JavaScript on wasm, wasm-gc, js and native.

The root read_diagram API returns ParsedDiagram::Flowchart. Its syntax tree reproduces every source code unit, including comments, front matter, directives, CRLF and malformed regions. The typed AST keeps the header and shared grammar statements. print_diagram writes typed values canonically; reading the result preserves the logical AST. Existing sequence-only read, print, ReadResult and to_sequence retain their types and behavior.

to_flowchart returns an immutable moonrockz/diagrams/flowchart model and conversion findings. A source such as this keeps Validation as an ordinary group, with no responsibility lane:

Implicit nodes, repeated declarations, grouped endpoints, parallel edges, subgraphs, local direction, shape metadata and edge markers follow pinned Mermaid rules. Top-level subgraphs remain groups. swimlane-beta still has its separate responsibility-lane policy. Diamond shape alone does not assign a process-execution role. Source bindings on converted node and connection occurrences identify their original statements.

render_svg dispatches flowchart source to the shared SVG renderer. The model also works directly with Diagram::Flowchart, public layout/legibility checks, shared adaptive/fixed themes and SVG scene bindings. It supports the pinned built-in vector shapes. Asset-dependent shapes retain their identity and return explicit rendering errors when unsupported. No image URL is fetched.

Class/style declarations, callbacks and renderer configuration survive source printing. Conversion reports unapplied presentation settings. URL click statements retain model links, subject to the shared renderer link policy. Callbacks never execute, and flowchart-elk does not load an external engine.

The usual animation API accepts the flowchart model. Its standalone player provides finite illustrative plans, caller-selected branch/loop repetitions, concurrent scenario groups, node visits, route/reachability inspection and keyboard-accessible playback controls. Reverse and bidirectional traversal follow edge markers. Unheaded edges require explicit undirected exploration; invisible layout edges and note attachments do not create routes. Collapsed descendants are outside the visible query scope. Results describe structure, not executable paths or evaluated conditions. The offline player respects reduced motion and hidden pages and downloads canonical static SVG.

Consumers that exhaustively match ParsedDiagram, DiagramTree, renderer Diagram or scene node-binding kinds must handle the new flowchart cases. No source-to-source conversion between Mermaid and PlantUML is provided.

Run mise run validate:flowchart-mermaid-corpus for frozen input/digest, documentation, grammar and portable embedding checks. Run mise run flowchart-mermaid-corpus:reference -- --check for the independent pinned Mermaid source/canonical oracle. The committed corpus covers all 114 flowchart documentation examples, the shared grammar and shapes, and 148 accepted graph fixtures plus three recorded upstream refusals. Normal tests use committed reference data without a browser or network.

Reader and printer nodes limits count AST node-declaration and group records; edges limits count AST link records. A repeated node spelling still has a separate declaration record. Conversion applies the same fields to normalized distinct elements and expanded connections. Thus a grouped edge can fit one AST link while exceeding its converted edge budget. Exhaustion preserves the source tree and returns no complete AST, model or printed output for the failed phase.