feat(dashboard): add sensitive data toggle to flow chart

Add an eye toggle in the flow section header that masks sensitive node
labels (users, tokens, nodes, groups, channels) in the Sankey while keeping
model names visible. Masking only rewrites display text; nodes stay distinct
via their key so graph structure, links, and highlighting are unaffected.

web/default/src/features/dashboard/lib/flow.ts

@@ -77,6 +77,7 @@ type FlowGraphOptions = {
   otherNodeLabel?: (kind: FlowNodeKind) => string
   activeNode?: FlowNodeFilter
   activeLink?: FlowLinkSelection
+  maskSensitive?: boolean
 }
 
 type FlowHighlightSets = {
@@ -127,6 +128,18 @@ const DEFAULT_OTHER_FLOW_NODE_LABELS: Record<FlowNodeKind, string> = {
   channel: 'Other channels',
 }
 
+// Kinds whose labels can leak identity (people, keys, infra, business setup).
+// Model names are public, so they stay visible even when masking is on.
+const SENSITIVE_FLOW_KINDS = new Set<FlowNodeKind>([
+  'user',
+  'node',
+  'token',
+  'group',
+  'channel',
+])
+
+const OTHER_FLOW_NODE_ID_SET = new Set<string>(Object.values(OTHER_FLOW_NODE_IDS))
+
 function numberValue(value: unknown): number {
   const n = Number(value)
   return Number.isFinite(n) ? n : 0
@@ -663,6 +676,40 @@ function buildFlowHighlightSets(
   }
 }
 
+// Fully masks a label. Nodes stay distinct because the Sankey identifies them
+// by `key` (the node id), not by this display text, so identical masked labels
+// never merge.
+const FLOW_MASK_TEXT = '\u2022\u2022\u2022\u2022'
+
+function maskFlowLabel(label: string): string {
+  if (label.length === 0) return label
+  return FLOW_MASK_TEXT
+}
+
+// Masks sensitive node/link labels in place. Node identity (`id`) is untouched,
+// so links, highlighting, and layout stay exactly the same; only the rendered
+// text changes.
+function maskFlowGraphLabels(
+  nodes: Map<string, DashboardFlowNode>,
+  links: Map<string, DashboardFlowLink>
+): void {
+  const maskedById = new Map<string, string>()
+  for (const node of nodes.values()) {
+    if (!SENSITIVE_FLOW_KINDS.has(node.kind)) continue
+    if (OTHER_FLOW_NODE_ID_SET.has(node.id)) continue
+    const masked = maskFlowLabel(node.label)
+    node.label = masked
+    maskedById.set(node.id, masked)
+  }
+  if (maskedById.size === 0) return
+  for (const link of links.values()) {
+    const sourceMasked = maskedById.get(link.source)
+    if (sourceMasked !== undefined) link.sourceLabel = sourceMasked
+    const targetMasked = maskedById.get(link.target)
+    if (targetMasked !== undefined) link.targetLabel = targetMasked
+  }
+}
+
 function applyFlowHighlights(
   nodes: Iterable<DashboardFlowNode>,
   links: Iterable<DashboardFlowLink>,
@@ -738,6 +785,9 @@ function buildFlowGraph(
       addLink(links, source, target, metrics, metric, color, root.id)
     }
   }
+  if (options.maskSensitive) {
+    maskFlowGraphLabels(nodes, links)
+  }
   applyFlowHighlights(
     nodes.values(),
     links.values(),
@@ -948,6 +998,7 @@ export function buildDashboardFlowData(
         otherNodeLabel: options.otherNodeLabel,
         activeNode: options.activeNode,
         activeLink: options.activeLink,
+        maskSensitive: options.maskSensitive,
       }
     ),
     filterOptions: {