Archify Diagram Viewer 0.1.0

VS Code extension that previews Archify diagrams from their JSON sources (live, as you type) and opens rendered Archify HTML in a viewer tab. Bundles the Archify 3.0.1 renderer and runs it on VS Code's Node runtime. Adds validation diagnostics, JSON schema help, source-link navigation, export saving, render-to-file and open-in-browser commands. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-30 12:40:55 +03:00
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+# Data Flow Renderer
+
+Render `diagram_type: "dataflow"` JSON files into the standard Archify HTML
+template.
+
+```bash
+node archify/renderers/dataflow/render-dataflow.mjs input.dataflow.json output.html
+```
+
+The renderer validates input against `archify/schemas/dataflow.schema.json`
+with the bundled standalone validator. No dependency installation is required.
+
+If `output.html` is omitted, the renderer uses the required `meta.output` value
+from the JSON file.
+
+## Input
+
+Data-flow JSON files must set:
+
+```json
+{
+  "schema_version": 1,
+  "diagram_type": "dataflow",
+  "meta": {
+    "title": "Product Analytics Data Flow",
+    "output": "product-analytics-dataflow.html",
+    "viewBox": [940, 720]
+  },
+  "stages": [],
+  "nodes": [],
+  "flows": [],
+  "cards": []
+}
+```
+
+A complete worked example lives at
+`archify/examples/product-analytics.dataflow.json`.
+
+The schema lives at:
+
+```text
+archify/schemas/dataflow.schema.json
+```
+
+## Legend
+
+The default visual legend derives kinds from `flows[].variant` (omitting
+`variant` means `default`) and adds `database` only when a database node exists.
+Supported `meta.legend.entries` keys, in stable order, are `emphasis`,
+`security`, `dashed`, `database`, and `default`. Flow variants remain
+visual-only because Archify has no compiled edge-kind facts in this slice. A
+present `database` entry is different: it comes from exact
+`nodes[].type: "database"` facts, so it publishes the normal Semantic Legend
+count, accessible name, and keyboard interaction. Forcing `database` visible
+without a database node keeps it visual-only.
+
+## Layout budget
+
+| Constant | Value |
+|----------|-------|
+| viewBox | default `[940, 720]`; schema minimum `[360, 360]` |
+| Stages (2–5) | centers at x = 100 + stage×215; stage band 168 wide, header at y 46 |
+| Row tops (`row` 0–4) | y = 128, 242, 356, 470, 584 (plus `yOffset`) |
+| Default node | 112×58 |
+| Node area | x within `[24, width − 24]`; y within `[104, height − 74]` |
+| Node spacing | ≥10px between any two nodes (checked across stages and rows) |
+| Flow length | ≥34px between endpoints |
+| Legend row | y = height − 36 |
+
+Route presets for flows: `straight`, `vertical-channel`, `bottom-channel`,
+`top-channel`, explicit `via` points, or the default `auto` (midpoint elbow).
+
+## Design Rules
+
+- Use stages for data lifecycle boundaries: source, ingest, process, store,
+  consume.
+- Place nodes by stage index and row index; do not hand-place raw SVG for the
+  common case.
+- Use flow labels to name the data asset, not the transport primitive:
+  `clickstream`, `identity map`, `normalized facts`, `feature vectors`.
+- Use `classification` for short sensitivity or governance context:
+  `PII touch`, `non-PII`, `approved only`, `batch`, `read-only`.
+- Use `security` for PII, policy, consent, access-control, or restricted joins.
+- Use `emphasis` for the primary data path and `dashed` for async or batch
+  derivations.
+- Keep labels short enough to fit in narrow previews.
+
+Schema violations exit non-zero with path-prefixed messages annotated with the
+element's id or label. The renderer additionally fails when it can detect
+layout problems, including missing stages, duplicate node IDs, nodes outside
+the readable diagram area, node overlap, labels colliding with nodes or other
+labels, labels wider than their node, unknown flow endpoints, missing flow
+labels, unreadably short flows, flows crossing unrelated nodes (2px Clean Flow
+clearance), or stages that exceed the viewBox. Stage frames remain intentional
+pass-through containers. Text width
+is estimated CJK-aware: fullwidth glyphs count as two units.
+
+Set `meta.quality_profile` to `showcase` for polished delivery. Unrelated proper
+X crossings then fail with `composition/proper-crossing`; default `standard`
+keeps them as artifact-receipt warnings. Collinear stage corridors are outside
+the proper-X rule, but a separate gate warns in `standard` and fails in
+`showcase` when unrelated flows overlap for at least 8px. Shared semantic
+endpoints, point touches, and shorter overlaps remain valid. Showcase also
+rejects any route segment below 8px and any interior turn segment below 16px;
+ordinary 8–15px endpoint stubs remain valid.
@@ -0,0 +1,544 @@
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { esc, renderDefinitions, renderSemanticSigil, textUnits } from '../shared/utils.mjs';
+import { animateAttr, focusEdgeAttrs, focusNodeAttrs, focusNodeTitle, loadDiagramWithBrandMarks, writeDiagram, svgAccessibleText, svgRootAttrs } from '../shared/cli.mjs';
+import { throwDiagnosticProblems } from '../shared/diagnostics.mjs';
+import { resolveLegend, renderLegend as renderResolvedLegend } from '../shared/legend.mjs';
+import { availableNodeTextWidth, fittedNodeFontSize, minimumNodeTextWidth, nodeLabelLayout } from '../shared/text-fit.mjs';
+import { brandLabelFitWidth, brandMarkFor, brandMetadataFor, brandTopRailProblem, renderBrandMark } from '../shared/brand-marks.mjs';
+import { translateMessage as i18nText } from '../shared/i18n.mjs';
+import {
+  asArray,
+  isFinitePoint,
+  rectsOverlap,
+  cleanEndpointSideProblems,
+  cleanFlowProblems,
+  cleanCrossingProblems,
+  cleanAmbiguousCorridorProblems,
+  cleanBorderRunProblems,
+  cleanRouteRhythmProblems,
+  cleanLabelRouteClearanceProblems,
+  cleanLabelCanvasContainmentProblems,
+  suggestLabelObstacleFix,
+  suggestLabelPairFix,
+  anchor,
+  automaticPortSpread,
+  legacyDefaultFromSide as defaultFromSide,
+  legacyDefaultToSide as defaultToSide,
+  chosenSide,
+  polylinePath,
+  routePointsValue,
+  authoredStraightRouteAttrs,
+  labelPoint,
+  componentFill,
+  componentText,
+  arrowClassMap,
+  edgeLabelAccent
+} from '../shared/geometry.mjs';
+
+const nodeTextFit = {
+  sublabelPreferred: 7,
+  sublabelMinimum: 6,
+  tagPreferred: 7,
+  tagMinimum: 6,
+};
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const { diagram: dataflow, template, outPath, sourceEvidence } = await loadDiagramWithBrandMarks({
+  rendererDir: __dirname,
+  diagramType: 'dataflow',
+  defaultExample: 'product-analytics.dataflow.json'
+});
+
+const viewBox = dataflow.meta?.viewBox || [940, 720];
+const layout = {
+  stageY: 46,
+  stageH: 36,
+  stageBottomPad: 74,
+  leftX: 100,
+  colGap: 215,
+  stageW: 168,
+  nodeW: 112,
+  nodeH: 58,
+  rowYs: [128, 242, 356, 470, 584],
+  labelH: 16
+};
+
+function flowLabelSize(flow) {
+  const longestLine = Math.max(textUnits(flow.label), textUnits(flow.classification || ''));
+  return {
+    width: Math.round(Math.max(34, longestLine * 4.9 + 12) * 10) / 10,
+    height: flow.classification ? 27 : layout.labelH,
+  };
+}
+
+function stageX(index) {
+  return layout.leftX + index * layout.colGap;
+}
+
+function stageFrame(stage, index) {
+  return {
+    id: index,
+    label: stage.label,
+    kind: 'stage',
+    x: stageX(index) - layout.stageW / 2,
+    y: layout.stageY,
+    width: layout.stageW,
+    height: viewBox[1] - layout.stageY - layout.stageBottomPad,
+    radius: 10,
+  };
+}
+
+const compositionFrames = asArray(dataflow.stages).map(stageFrame);
+
+function measureNode(node) {
+  const width = node.width || layout.nodeW;
+  const height = node.height || layout.nodeH;
+  const cx = stageX(node.stage);
+  const y = layout.rowYs[node.row] + (node.yOffset || 0);
+  return {
+    ...node,
+    width,
+    height,
+    cx,
+    cy: y + height / 2,
+    x: cx - width / 2,
+    y
+  };
+}
+
+const nodes = new Map(asArray(dataflow.nodes).map((node) => [node.id, measureNode(node)]));
+const nodeSteps = new Map();
+for (const [index, flow] of asArray(dataflow.flows).entries()) {
+  if (!nodeSteps.has(flow.from)) nodeSteps.set(flow.from, index);
+  if (!nodeSteps.has(flow.to)) nodeSteps.set(flow.to, index + 1);
+}
+for (const [index, node] of asArray(dataflow.nodes).entries()) {
+  if (!nodeSteps.has(node.id)) nodeSteps.set(node.id, index);
+}
+
+function validateDataflow() {
+  const problems = [];
+  if (nodes.size !== asArray(dataflow.nodes).length) problems.push('Node ids must be unique.');
+
+  const stageCount = asArray(dataflow.stages).length;
+  for (const node of nodes.values()) {
+    if (typeof node.stage !== 'number' || node.stage < 0 || node.stage >= stageCount) {
+      problems.push(`Node "${node.id}" uses invalid stage ${node.stage} — valid stages are 0..${stageCount - 1}.`);
+    }
+    if (typeof node.row !== 'number' || node.row < 0 || node.row >= layout.rowYs.length) {
+      problems.push(`Node "${node.id}" uses invalid row ${node.row} — valid rows are 0..${layout.rowYs.length - 1}.`);
+    }
+    if (!isFinitePoint(node.x, node.y, node.cx, node.cy)) {
+      problems.push(`Node "${node.id}" produced non-finite coordinates — check stage, row, width, height, and yOffset are numbers.`);
+      continue;
+    }
+    if (node.x < 24 || node.x + node.width > viewBox[0] - 24) {
+      problems.push(`Node "${node.id}" exceeds the horizontal bounds of the viewBox — reduce node.width or increase meta.viewBox[0].`);
+    }
+    if (node.y < layout.stageY + layout.stageH + 22 || node.y + node.height > viewBox[1] - layout.stageBottomPad) {
+      problems.push(`Node "${node.id}" exceeds the readable diagram area — keep y between ${layout.stageY + layout.stageH + 22} and ${viewBox[1] - layout.stageBottomPad} (adjust row/yOffset or increase meta.viewBox[1]).`);
+    }
+    const estLabelW = textUnits(node.label) * 6.2;
+    if (estLabelW > node.width + 6) {
+      problems.push(`Label "${node.label}" (~${Math.round(estLabelW)}px) is wider than node "${node.id}" (${node.width}px) — shorten the label or increase node.width.`);
+    }
+    const brandRailProblem = brandTopRailProblem(node, node.width, 8);
+    if (brandRailProblem) problems.push(brandRailProblem);
+    // sublabel and tag render as single unwrapped <text> elements; shrink-to-fit
+    // handles the ordinary case, this rejects what it cannot rescue.
+    const availableTextW = availableNodeTextWidth(node.width);
+    for (const [field, value, minimum] of [
+      ['Sublabel', node.sublabel, nodeTextFit.sublabelMinimum],
+      ['Tag', node.tag, nodeTextFit.tagMinimum],
+    ]) {
+      if (!value) continue;
+      const minimumW = minimumNodeTextWidth(value, minimum);
+      if (minimumW > availableTextW) {
+        problems.push(`${field} "${value}" needs ~${Math.ceil(minimumW)}px at the ${minimum}px legible minimum, but node "${node.id}" provides ${availableTextW}px — shorten the ${field.toLowerCase()} or increase node.width.`);
+      }
+    }
+  }
+
+  const nodeList = asArray(dataflow.nodes);
+  for (let i = 0; i < nodeList.length; i += 1) {
+    for (let j = i + 1; j < nodeList.length; j += 1) {
+      const a = nodes.get(nodeList[i].id);
+      const b = nodes.get(nodeList[j].id);
+      if (rectsOverlap(a, b, 10)) {
+        problems.push(`Nodes "${a.id}" and "${b.id}" are less than 10px apart — move one to another stage/row or adjust yOffset.`);
+      }
+    }
+  }
+
+  for (const flow of asArray(dataflow.flows)) {
+    if (!nodes.has(flow.from)) problems.push(`Flow "${flow.label || flow.from}" references unknown source "${flow.from}".`);
+    if (!nodes.has(flow.to)) problems.push(`Flow "${flow.label || flow.to}" references unknown target "${flow.to}".`);
+    if (!flow.label) problems.push(`Flow "${flow.from}" -> "${flow.to}" must include a short data label.`);
+    if (nodes.has(flow.from) && nodes.has(flow.to)) {
+      const routed = pathFor(flow);
+      const [start, end] = [routed.points[0], routed.points[routed.points.length - 1]];
+      const distance = Math.hypot(end[0] - start[0], end[1] - start[1]);
+      if (distance < 34) problems.push(`Flow "${flow.label}" is too short (${Math.round(distance)}px; minimum 34px) — route it through a channel or spread its nodes.`);
+      if (Array.isArray(flow.via)) {
+        for (let segmentIndex = 0; segmentIndex < routed.points.length - 1; segmentIndex += 1) {
+          const segmentStart = routed.points[segmentIndex];
+          const segmentEnd = routed.points[segmentIndex + 1];
+          const isDiagonal = Math.abs(segmentStart[0] - segmentEnd[0]) > 0.01
+            && Math.abs(segmentStart[1] - segmentEnd[1]) > 0.01;
+          if (!isDiagonal) continue;
+          const viaIndex = Math.min(segmentIndex, flow.via.length - 1);
+          problems.push(`Flow "${flow.label}" has a diagonal segment from (${segmentStart.join(', ')}) to (${segmentEnd.join(', ')}) — align via[${viaIndex}] with its adjacent point by sharing the same x or y coordinate.`);
+        }
+      }
+    }
+  }
+
+  problems.push(...cleanEndpointSideProblems({
+    relations: dataflow.flows,
+    endpointIds: new Set(nodes.keys()),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    fromSideFor: (flow) => flowSides(flow).fromSide,
+    toSideFor: (flow) => flowSides(flow).toSide,
+    routeHint: 'keep automatic routing, or choose fromSide/toSide and via points whose first and final segments cross node borders perpendicularly',
+  }));
+  problems.push(...cleanFlowProblems({
+    relations: dataflow.flows,
+    obstacles: nodes.values(),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    obstacleKind: 'node',
+    routeHint: 'adjust fromSide/toSide, set route/via or channelX/channelY, or move the node to another stage/row'
+  }));
+  problems.push(...cleanCrossingProblems({
+    relations: dataflow.flows,
+    endpointIds: new Set(nodes.keys()),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+    routeHint: 'adjust route/via or channelX/channelY so the flows use separate stage corridors'
+  }));
+  problems.push(...cleanAmbiguousCorridorProblems({
+    relations: dataflow.flows,
+    endpointIds: new Set(nodes.keys()),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+    routeHint: 'adjust route/via or channelX/channelY so unrelated flows do not visually merge'
+  }));
+  problems.push(...cleanBorderRunProblems({
+    relations: dataflow.flows,
+    endpointIds: new Set(nodes.keys()),
+    frames: compositionFrames,
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+    routeHint: 'adjust route/via or channelX/channelY so the flow crosses the stage perpendicularly instead of following its border'
+  }));
+  problems.push(...cleanRouteRhythmProblems({
+    relations: dataflow.flows,
+    endpointIds: new Set(nodes.keys()),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+    routeHint: 'adjust route/via or channelX/channelY so each turn uses a clear inter-stage corridor'
+  }));
+
+  const labelRects = [];
+  for (const [flowIndex, flow] of asArray(dataflow.flows).entries()) {
+    if (!flow.label || !nodes.has(flow.from) || !nodes.has(flow.to)) continue;
+    const [lx, ly] = labelPoint(flow, pathFor(flow).points);
+    const { width, height } = flowLabelSize(flow);
+    labelRects.push({ relation: flow, relationIndex: flowIndex, label: flow.label, x: lx - width / 2, y: ly - 11, width, height, lx, ly });
+  }
+  for (const rect of labelRects) {
+    for (const node of nodes.values()) {
+      if (rectsOverlap(rect, node, -2)) {
+        problems.push(`Label "${rect.label}" overlaps node "${node.id}" — adjust labelDx/labelDy/labelSegment or set labelAt.\n${suggestLabelObstacleFix(rect, rect.lx, rect.ly, node, 'node', viewBox, nodes.values())}`);
+      }
+    }
+  }
+  for (let i = 0; i < labelRects.length; i += 1) {
+    for (let j = i + 1; j < labelRects.length; j += 1) {
+      if (rectsOverlap(labelRects[i], labelRects[j], -2)) {
+        problems.push(`Labels "${labelRects[i].label}" and "${labelRects[j].label}" overlap — adjust labelDx/labelDy.\n${suggestLabelPairFix(labelRects[i], labelRects[j])}`);
+      }
+    }
+  }
+  problems.push(...cleanLabelRouteClearanceProblems({
+    relations: dataflow.flows,
+    labels: labelRects,
+    endpointIds: new Set(nodes.keys()),
+    pathFor,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+    routeHint: 'adjust labelAt, labelDx, labelDy, or labelSegment; otherwise adjust the other flow route/via/channelX/channelY'
+  }));
+  problems.push(...cleanLabelCanvasContainmentProblems({
+    labels: labelRects,
+    viewBox,
+    diagramType: 'dataflow',
+    relationCollection: 'flows',
+    profile: dataflow.meta?.quality_profile,
+  }));
+
+  const lastStageX = stageX(asArray(dataflow.stages).length - 1);
+  if (lastStageX + layout.stageW / 2 > viewBox[0] - 24) {
+    problems.push(`Stages exceed viewBox width — set meta.viewBox[0] to at least ${Math.ceil(lastStageX + layout.stageW / 2 + 24)}.`);
+  }
+
+  if (problems.length) {
+    throwDiagnosticProblems('Data-flow layout validation failed', problems, {
+      subject: { diagramType: 'dataflow' },
+    });
+  }
+}
+
+function routeVia(flow, from, to, start, end) {
+  if (flow.via) return flow.via;
+  switch (flow.route || 'auto') {
+    case 'straight':
+      return [];
+    case 'vertical-channel': {
+      const x = flow.channelX ?? start[0] + (end[0] > start[0] ? 44 : -44);
+      return [[x, start[1]], [x, end[1]]];
+    }
+    case 'bottom-channel': {
+      const y = flow.channelY ?? Math.max(from.y + from.height, to.y + to.height) + 26;
+      return [[start[0], y], [end[0], y]];
+    }
+    case 'top-channel': {
+      const y = flow.channelY ?? Math.min(from.y, to.y) - 24;
+      return [[start[0], y], [end[0], y]];
+    }
+    case 'auto':
+    default: {
+      if (Math.abs(start[1] - end[1]) < 4) return [];
+      const midX = start[0] + (end[0] - start[0]) / 2;
+      return [[midX, start[1]], [midX, end[1]]];
+    }
+  }
+}
+
+const pathCache = new Map();
+
+function flowSides(flow) {
+  const from = nodes.get(flow.from);
+  const to = nodes.get(flow.to);
+  return {
+    fromSide: chosenSide(flow.fromSide, defaultFromSide(from, to)),
+    toSide: chosenSide(flow.toSide, defaultToSide(from, to)),
+  };
+}
+
+const automaticPorts = automaticPortSpread(dataflow.flows, nodes, {
+  sideFor: (flow, endpoint) => flowSides(flow)[endpoint === 'source' ? 'fromSide' : 'toSide'],
+});
+
+function pathFor(flow) {
+  if (pathCache.has(flow)) return pathCache.get(flow);
+  const from = nodes.get(flow.from);
+  const to = nodes.get(flow.to);
+  const ports = automaticPorts.get(flow);
+  const { fromSide, toSide } = flowSides(flow);
+  const start = ports?.from || anchor(from, fromSide);
+  const end = ports?.to || anchor(to, toSide);
+  // Drop consecutive duplicate points so a purely vertical (or horizontal)
+  // auto-route never emits a zero-length final segment — SVG derives
+  // marker-end orientation from the last segment, and a degenerate segment
+  // leaves the arrowhead angle undefined (see #169).
+  const rawPoints = [start, ...routeVia(flow, from, to, start, end), end];
+  const points = [];
+  for (const p of rawPoints) {
+    const prev = points.at(-1);
+    if (!prev || Math.abs(p[0] - prev[0]) > 0.0001 || Math.abs(p[1] - prev[1]) > 0.0001) {
+      points.push(p);
+    }
+  }
+  // Guard against an all-degenerate route (e.g. start === end): keep both
+  // endpoints so the path is still well-formed even if the marker is hidden.
+  if (points.length < 2) points.push(end);
+  const routed = { d: polylinePath(points), points };
+  pathCache.set(flow, routed);
+  return routed;
+}
+
+// Header measurement follows 276970789's #257, including the ordinal.
+// Long titles wrap at the same legible floor instead of becoming invalid input.
+function stageHeaderText(stage, index) {
+  return `${String(index + 1).padStart(2, '0')} / ${stage.label}`;
+}
+
+function renderStageHeader(stage, index, cx) {
+  const text = stageHeaderText(stage, index);
+  const font = fittedNodeFontSize(text, layout.stageW, 9, 7);
+  const available = availableNodeTextWidth(layout.stageW);
+  const open = `<text x="${cx}" y="${layout.stageY + 22}" class="t-dim" font-size="${font}" font-weight="600" text-anchor="middle">`;
+  if (minimumNodeTextWidth(text, font) <= available) return `${open}${esc(text)}</text>`;
+  const lines = [];
+  let line = '';
+  // Prefer word boundaries; split oversized words and CJK by grapheme, without
+  // dropping whitespace or splitting a combining character/emoji sequence.
+  const segmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' });
+  for (const word of text.match(/\s+|\S+/gu) || []) {
+    if (line && minimumNodeTextWidth(line + word, font) > available) {
+      lines.push(line); line = '';
+    }
+    for (const { segment } of segmenter.segment(word)) {
+      if (line && minimumNodeTextWidth(line + segment, font) > available) {
+        lines.push(line); line = '';
+      }
+      line += segment;
+    }
+  }
+  if (line) lines.push(line);
+  // Explicit node geometry is authoritative. Do not turn an old horizontal
+  // overflow into a new collision with nodes when the header area is packed.
+  const firstNodeY = Math.min(...[...nodes.values()].filter(node => node.stage === index).map(node => node.y),
+    viewBox[1] - layout.stageBottomPad);
+  const lastLineBottom = layout.stageY + 22 + (lines.length - 1) * (font + 4) + font * 0.3;
+  if (lastLineBottom > firstNodeY - 4) return `${open}${esc(text)}</text>`;
+  const content = lines.length === 1 ? esc(text) : lines.map((line, i) =>
+    `<tspan x="${cx}" dy="${i ? font + 4 : 0}">${esc(line)}</tspan>`).join('');
+  return `${open}${content}</text>`;
+}
+
+function renderStage(stage, index) {
+  const frame = compositionFrames[index];
+  const cx = stageX(index);
+  return `        <rect data-graph-role="structural-frame" data-composition-frame-kind="stage" data-composition-frame-id="${index}" x="${frame.x}" y="${frame.y}" width="${frame.width}" height="${frame.height}" rx="${frame.radius}" class="c-lane" stroke-width="1"/>
+        ${renderStageHeader(stage, index, cx)}`;
+}
+
+function renderNode(node) {
+  const fill = componentFill[node.type] || 'c-external';
+  const accent = componentText[node.type] || 't-muted';
+  const hasSub = node.sublabel != null && node.sublabel !== '';
+  const labelFontSize = fittedNodeFontSize(node.label, brandLabelFitWidth(node, node.width), 10, 8);
+  const sublabelFontSize = fittedNodeFontSize(node.sublabel, node.width, nodeTextFit.sublabelPreferred, nodeTextFit.sublabelMinimum);
+  const tagFontSize = fittedNodeFontSize(node.tag, node.width, nodeTextFit.tagPreferred, nodeTextFit.tagMinimum);
+  const textRows = [{ text: node.label, font: labelFontSize, y: 21 }];
+  if (hasSub) textRows.push({ text: node.sublabel, font: sublabelFontSize, y: 37 });
+  if (node.tag) textRows.push({ text: node.tag, font: tagFontSize, y: node.height - 11 });
+  const labelLayout = nodeLabelLayout({ width: node.width, height: node.height, rows: textRows,
+    brand: Boolean(brandMarkFor(node)), source: Boolean(sourceEvidence?.nodes?.[node.id]?.length) });
+  const sub = hasSub
+    ? `\n          <text data-detail="context" x="${node.cx}" y="${node.y + labelLayout.ys[1]}" class="t-muted" font-size="${sublabelFontSize}" text-anchor="middle">${esc(node.sublabel)}</text>`
+    : '';
+  const tag = node.tag
+    ? `\n        <text data-detail="fine" x="${node.cx}" y="${node.y + labelLayout.ys[hasSub ? 2 : 1]}" class="${accent}" font-size="${tagFontSize}" text-anchor="middle">${esc(node.tag)}</text>`
+    : '';
+  const stage = asArray(dataflow.stages)[node.stage];
+  const context = stage
+    ? `${String(node.stage + 1).padStart(2, '0')} / ${stage.label}`
+    : i18nText(dataflow.meta.locale, 'node.context.dataflow');
+  const brand = renderBrandMark(node, { x: node.x + node.width - 22, y: node.y + 6 });
+  const passport = { kind: node.type, sublabel: node.sublabel, tag: node.tag, context, ...brandMetadataFor(node) };
+  return `        <g ${focusNodeAttrs(node.id, node.label, passport, dataflow.meta.locale)}>
+          ${focusNodeTitle(node.label, passport)}
+          <rect x="${node.x}" y="${node.y}" width="${node.width}" height="${node.height}" rx="6" class="c-mask"/>
+          <rect x="${node.x}" y="${node.y}" width="${node.width}" height="${node.height}" rx="6" class="${fill}"${animateAttr(dataflow.meta, 'node', nodeSteps.get(node.id))} stroke-width="1.5"/>
+          ${renderSemanticSigil(node.type, { icon: node.icon, x: node.x + 6, y: node.y + labelLayout.sigilY, size: labelLayout.sigilSize })}${brand ? `\n          ${brand}` : ''}
+          <text data-node-label=""${hasSub ? ' data-detail-anchor=""' : ''} x="${node.x + labelLayout.x}" y="${node.y + labelLayout.ys[0]}" class="t-primary" font-size="${labelFontSize}" font-weight="600" text-anchor="middle">${esc(node.label)}</text>${sub}${tag}
+        </g>`;
+}
+
+function renderFlowPath(flow, index) {
+  const [cls, marker] = arrowClassMap[flow.variant || 'default'] || arrowClassMap.default;
+  const routed = pathFor(flow);
+  const strokeWidth = flow.width || (flow.variant === 'emphasis' ? 1.8 : 1.4);
+  return `        <path ${focusEdgeAttrs(flow.from, flow.to, flow.label, index, flow.id)} data-composition-points="${routePointsValue(routed.points)}"${authoredStraightRouteAttrs(flow, routed.points)} d="${routed.d}" class="${cls}"${animateAttr(dataflow.meta, 'edge', index)} stroke-width="${strokeWidth}" marker-end="url(#${marker})"/>`;
+}
+
+function renderFlowLabel(flow, index) {
+  const routed = pathFor(flow);
+  const [lx, ly] = labelPoint(flow, routed.points);
+  const { width: labelW, height: labelH } = flowLabelSize(flow);
+  const classification = flow.classification
+    ? `\n        <text data-detail="fine" x="${lx}" y="${ly + 11}" class="t-dim" font-size="7" text-anchor="middle">${esc(flow.classification)}</text>`
+    : '';
+  return `        <g data-detail="context" ${focusEdgeAttrs(flow.from, flow.to, flow.label, index, flow.id)}>
+          <rect x="${lx - labelW / 2}" y="${ly - 11}" width="${labelW}" height="${labelH}" rx="4" class="c-mask"/>
+          <text x="${lx}" y="${ly}" class="${edgeLabelAccent(flow.variant)}" font-size="8" text-anchor="middle">${esc(flow.label)}</text>${classification}
+        </g>`;
+}
+
+const LEGEND_CATALOG = [
+  { kind: 'emphasis', className: 'a-emphasis', marker: 'arrowhead-emphasis', strokeWidth: 1.8, swatchWidth: 34, swatchGap: 9, interactive: false },
+  { kind: 'security', className: 'a-security', marker: 'arrowhead-security', swatchWidth: 34, swatchGap: 9, interactive: false },
+  { kind: 'dashed', className: 'a-dashed', marker: 'arrowhead-dashed', swatchWidth: 34, swatchGap: 9, interactive: false },
+  { kind: 'database' },
+  { kind: 'default', className: 'a-default', marker: 'arrowhead', swatchWidth: 34, swatchGap: 9, interactive: false },
+].map((entry) => ({
+  ...entry,
+  label: i18nText(dataflow.meta.locale, `legend.dataflow.${entry.kind}`),
+}));
+
+function renderLegend() {
+  const presentKinds = new Set(asArray(dataflow.flows).map((flow) => flow.variant || 'default'));
+  if ([...nodes.values()].some((node) => node.type === 'database')) presentKinds.add('database');
+  const entries = resolveLegend(dataflow.meta?.legend, LEGEND_CATALOG, presentKinds);
+  return renderResolvedLegend({
+    entries,
+    locale: dataflow.meta.locale,
+    layout: {
+      x: 40,
+      baselineY: viewBox[1] - 36,
+      width: viewBox[0] - 80,
+      minTitleY: viewBox[1] - 66,
+      unfit: dataflow.meta?.legend === undefined ? 'hide' : 'error',
+      diagramType: 'dataflow',
+    },
+    renderSwatch: (entry) => entry.kind === 'database'
+      ? `<rect x="${entry.x}" y="${entry.baseline - 8}" width="14" height="9" rx="2" class="c-database" stroke-width="1"/>`
+      : `<path d="M ${entry.x} ${entry.baseline - 3} L ${entry.x + 34} ${entry.baseline - 3}" class="${entry.className}" stroke-width="${entry.strokeWidth || 1.4}" marker-end="url(#${entry.marker})"/>`,
+  });
+}
+
+function renderSvg() {
+  // Same default-canvas contract as lifecycle: 940x720 is below the 1.55 wide
+  // ratio, so without intrinsic-height the desktop Reader can neither narrow
+  // nor scroll it and every default dataflow fails the browser gate.
+  const readerFit = dataflow.meta?.viewBox ? '' : ' data-reader-fit="intrinsic-height"';
+  return `      <svg viewBox="0 0 ${viewBox[0]} ${viewBox[1]}"${readerFit} ${svgRootAttrs(dataflow.meta)}>
+${svgAccessibleText(dataflow.meta, 'dataflow')}
+${renderDefinitions()}
+
+        <!-- Background Grid -->
+        <rect width="100%" height="100%" fill="url(#grid)" />
+
+        <!-- Data Stages -->
+${dataflow.stages.map(renderStage).join('\n\n')}
+
+        <!-- Flow paths -->
+${asArray(dataflow.flows).map(renderFlowPath).join('\n')}
+
+        <!-- Nodes -->
+${[...nodes.values()].map(renderNode).join('\n\n')}
+
+        <!-- Flow labels -->
+${asArray(dataflow.flows).map(renderFlowLabel).join('\n')}
+
+        <!-- Legend -->
+${renderLegend()}
+      </svg>`;
+}
+
+validateDataflow();
+writeDiagram({
+  outPath,
+  template,
+  diagramType: 'dataflow',
+  meta: dataflow.meta,
+  svg: renderSvg(),
+  cards: dataflow.cards,
+  sourceEvidence,
+});