fix: restore readable Knowledge Graph design tokens

frontend/src/KnowledgeGraph.css

@@ -20,9 +20,9 @@
 .knowledge-graph-controls button {
   align-items: center;
   background: var(--surface);
-  border: 1px solid var(--line-strong);
+  border: 1px solid var(--border);
   border-radius: 0.45rem;
-  color: var(--ink);
+  color: var(--text-h);
   display: inline-flex;
   font: inherit;
   justify-content: center;
@@ -44,7 +44,7 @@
 }
 
 .knowledge-graph-controls span {
-  color: var(--muted);
+  color: var(--text-muted);
   font-variant-numeric: tabular-nums;
   min-width: 3.25rem;
   text-align: center;
@@ -55,14 +55,14 @@
 }
 
 .knowledge-graph-description {
-  color: var(--muted);
+  color: var(--text-muted);
   margin: 0.2rem 0 0;
 }
 
 .knowledge-graph-viewport {
   cursor: grab;
   overflow: hidden;
-  border: 1px solid var(--line);
+  border: 1px solid var(--border);
   border-radius: 0.75rem;
   background: var(--surface);
   touch-action: none;
@@ -78,19 +78,19 @@
 }
 
 .knowledge-graph-arrow {
-  fill: var(--muted);
+  fill: var(--text-muted);
 }
 
 .knowledge-graph-edge path {
   fill: none;
   marker-end: inherit;
-  stroke: var(--line-strong);
+  stroke: var(--border);
   stroke-width: 1.3;
 }
 
 .knowledge-graph-node rect {
   fill: var(--surface);
-  stroke: var(--line-strong);
+  stroke: var(--border);
   stroke-width: 1.5;
 }
 
@@ -101,8 +101,8 @@
 }
 
 .knowledge-graph-node.evidence rect {
-  fill: color-mix(in srgb, var(--warning) 10%, var(--surface));
-  stroke: var(--warning);
+  fill: color-mix(in srgb, var(--color-accent-orange) 10%, var(--surface));
+  stroke: var(--color-accent-orange);
   stroke-dasharray: 4 3;
 }
 
@@ -122,18 +122,18 @@
 }
 
 .knowledge-graph-node-label {
-  fill: var(--ink);
+  fill: var(--text-h);
   font-size: 12px;
   font-weight: 650;
 }
 
 .knowledge-graph-node-type {
-  fill: var(--muted);
+  fill: var(--text-muted);
   font-size: 9px;
 }
 
 .knowledge-graph-evidence {
-  border-top: 1px solid var(--line);
+  border-top: 1px solid var(--border);
   padding-top: 0.7rem;
 }
 

frontend/src/KnowledgeGraph.css.test.ts

@@ -0,0 +1,15 @@
+/// <reference types="node" />
+import { readFileSync } from "node:fs";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const here = dirname(fileURLToPath(import.meta.url));
+const css = readFileSync(join(here, "KnowledgeGraph.css"), "utf-8");
+
+describe("Knowledge Graph CSS contract", () => {
+  it("uses only defined shared tokens for graph colors", () => {
+    expect(css).not.toMatch(/var\(\s*--(?:ink|muted|line|line-strong|warning)\b/);
+    expect(css).toContain("var(--color-accent-orange)");
+  });
+});

frontend/src/KnowledgeGraph.stories.tsx

@@ -0,0 +1,82 @@
+import type { Meta, StoryObj } from "@storybook/react-vite";
+import { KnowledgeGraphView } from "./KnowledgeGraph";
+import type { KnowledgeGraph } from "./api";
+
+const mixedStateGraph: KnowledgeGraph = {
+  post_id: "post-1",
+  nodes: [
+    {
+      id: "post-1",
+      node_type_code: "node_post",
+      node_id: "post-1",
+      label: "Case introduction meeting",
+      is_focus: true,
+    },
+    {
+      id: "team-1",
+      node_type_code: "node_team",
+      node_id: "team-1",
+      label: "Case design team",
+      ontology_label: "Team",
+      is_focus: false,
+      is_evidence_text_node: false,
+    },
+    {
+      id: "organization-1",
+      node_type_code: "node_corporate_entity",
+      node_id: "organization-1",
+      label: "Case main contractor",
+      ontology_label: "Organization",
+      is_focus: false,
+      is_evidence_text_node: true,
+    },
+    {
+      id: "project-1",
+      node_type_code: "node_project",
+      node_id: "project-1",
+      label: "Case grid project",
+      ontology_label: "Project",
+      is_focus: false,
+      is_evidence_text_node: true,
+    },
+  ],
+  edges: [
+    {
+      source: "post-1",
+      target: "team-1",
+      edge_type_code: "edge_mention",
+      ontology_label: "Mentioned in post",
+      confidence: 0.9,
+      evidence_post_ids: ["post-1"],
+    },
+    {
+      source: "organization-1",
+      target: "project-1",
+      edge_type_code: "edge_responsible_for",
+      ontology_label: "Responsible for",
+      confidence: 0.82,
+      evidence_text: "Main contract evidence",
+      evidence_post_ids: ["post-1"],
+    },
+  ],
+};
+
+const meta = {
+  title: "Evidence/KnowledgeGraph",
+  component: KnowledgeGraphView,
+  parameters: { layout: "padded" },
+} satisfies Meta<typeof KnowledgeGraphView>;
+
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+export const MixedNodeStates: Story = {
+  args: { graph: mixedStateGraph, onSelectPost: () => undefined },
+};
+
+export const EmptyState: Story = {
+  args: {
+    graph: { post_id: "post-1", nodes: [], edges: [] },
+    onSelectPost: () => undefined,
+  },
+};