Allow per-diagram legend labels and visibility

[hoangbn]

Problem

Archify hardcodes legend entries, so authors cannot make the legend match the diagram.

The data-flow legend always shows:

• primary data
• policy / PII
• async batch
• data store

These labels appear even when the diagram contains no PII, async processing, or data store.

The lifecycle legend always shows active, waiting, success, and failure. A diagram with no waiting state still shows waiting, while the valid start state has no legend entry.

waiting should remain a lifecycle concept. Authors should be able to hide it from diagrams where it does not apply.

The data store label is also misaligned because it uses y, while the adjacent labels use y + 3.

Repro

1. Default data flow shows all fixed labels

This source has one default flow between two backend nodes. It contains no PII, async batch, emphasis flow, or data store.

{
  "schema_version": 1,
  "diagram_type": "dataflow",
  "meta": { "title": "Default Flow Only" },
  "stages": [{ "label": "Input" }, { "label": "Output" }],
  "nodes": [
    { "id": "input", "type": "backend", "label": "Input", "stage": 0, "row": 0 },
    { "id": "output", "type": "backend", "label": "Output", "stage": 1, "row": 0 }
  ],
  "flows": [
    { "from": "input", "to": "output", "label": "request", "route": "straight" }
  ]
}

The rendered legend still shows primary data, policy / PII, async batch, and data store.

2. Lifecycle without waiting or failure still shows both

This source uses only start, active, and success.

{
  "schema_version": 1,
  "diagram_type": "lifecycle",
  "meta": { "title": "No Waiting or Failure", "viewBox": [720, 566] },
  "lanes": [{ "id": "main", "label": "Lifecycle" }],
  "states": [
    { "id": "started", "type": "start", "label": "Started", "lane": "main", "col": 0 },
    { "id": "running", "type": "active", "label": "Running", "lane": "main", "col": 1 },
    { "id": "completed", "type": "success", "label": "Completed", "lane": "main", "col": 2 }
  ],
  "transitions": [
    { "from": "started", "to": "running" },
    { "from": "running", "to": "completed" }
  ]
}

The legend shows zero-count waiting and failure / exit entries, but no start entry.

3. A legend override fails schema validation

Adding a legend property under meta:

"meta": {
  "title": "Attempted Legend Override",
  "legend": {
    "security": "restricted data",
    "dashed": "retry"
  }
}

fails with:

/meta must NOT have additional properties {"additionalProperty":"legend"}

Evidence

• Data-flow legend is hardcoded
• Data-flow schema has no legend configuration
• Lifecycle legend is hardcoded
• start and waiting are valid lifecycle state types
• data store uses a different text baseline

Expected behavior

Allow diagram authors to control which legend entries appear and what they are called.

The current legends can remain as defaults. Authors should be able to:

• Rename labels such as policy / PII and async batch.
• Hide entries that do not apply, such as waiting.
• Show entries the diagram needs, such as start.

All legend labels should use the same baseline.