diff --git a/apps/x/apps/renderer/src/components/chart-renderer.test.ts b/apps/x/apps/renderer/src/components/chart-renderer.test.ts
new file mode 100644
index 00000000..22c9273b
--- /dev/null
+++ b/apps/x/apps/renderer/src/components/chart-renderer.test.ts
@@ -0,0 +1,52 @@
+import { describe, expect, it } from 'vitest'
+import { parseChartSource } from './chart-renderer'
+
+const valid = {
+  chart: 'line',
+  x: 'day',
+  y: 'pct',
+  data: [{ day: 'Mon', pct: 0.1 }],
+}
+
+describe('parseChartSource', () => {
+  it('parses a valid config', () => {
+    const { config, invalid } = parseChartSource(JSON.stringify(valid))
+    expect(invalid).toBe(false)
+    expect(config?.chart).toBe('line')
+  })
+
+  it('treats incomplete JSON as streaming, not invalid', () => {
+    const partial = JSON.stringify(valid).slice(0, 25)
+    expect(parseChartSource(partial)).toEqual({ config: null, invalid: false })
+  })
+
+  it('flags complete-but-schema-invalid JSON as invalid', () => {
+    const { config, invalid } = parseChartSource(
+      JSON.stringify({ chart: 'line', data: [] }),
+    )
+    expect(config).toBeNull()
+    expect(invalid).toBe(true)
+  })
+
+  it('maps the label/value pie aliases to x/y', () => {
+    // Seen live: models emit pie configs with label/value field names.
+    const { config, invalid } = parseChartSource(
+      JSON.stringify({
+        chart: 'pie',
+        label: 'index',
+        value: 'drop',
+        data: [{ index: 'Nasdaq', drop: 2.4 }],
+      }),
+    )
+    expect(invalid).toBe(false)
+    expect(config?.x).toBe('index')
+    expect(config?.y).toBe('drop')
+  })
+
+  it('accepts a y array for multi-series charts', () => {
+    const { config } = parseChartSource(
+      JSON.stringify({ ...valid, y: ['a', 'b'] }),
+    )
+    expect(config?.y).toEqual(['a', 'b'])
+  })
+})
diff --git a/apps/x/apps/renderer/src/components/chart-renderer.tsx b/apps/x/apps/renderer/src/components/chart-renderer.tsx
index 7ecc217a..81095fbb 100644
--- a/apps/x/apps/renderer/src/components/chart-renderer.tsx
+++ b/apps/x/apps/renderer/src/components/chart-renderer.tsx
@@ -21,6 +21,33 @@ interface ChartRendererProps {
   source: string
 }
 
+/**
+ * Parse a chart fence body. Distinguishes the three states the renderer
+ * shows: `streaming` (JSON incomplete — the model is still writing),
+ * `invalid` (complete JSON that fails the schema), and a parsed config.
+ * Models occasionally reach for pie-flavored field names despite the
+ * skill's schema; the predictable label/value aliases map to x/y.
+ */
+export function parseChartSource(
+  source: string,
+): { config: blocks.ChartBlock | null; invalid: boolean } {
+  let parsed: unknown
+  try {
+    parsed = JSON.parse(source)
+  } catch {
+    return { config: null, invalid: false }
+  }
+  if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
+    const obj = parsed as Record<string, unknown>
+    if (obj.x === undefined && typeof obj.label === 'string') obj.x = obj.label
+    if (obj.y === undefined && typeof obj.value === 'string') obj.y = obj.value
+  }
+  const result = blocks.ChartBlockSchema.safeParse(parsed)
+  return result.success
+    ? { config: result.data, invalid: false }
+    : { config: null, invalid: true }
+}
+
 /**
  * Inline chart for chat messages: renders a ```chart fenced block (same
  * ChartBlockSchema the notes chart block uses) via recharts. Invalid or
@@ -33,26 +60,7 @@ export function ChartRenderer({ source }: ChartRendererProps) {
   const gridStroke = resolvedTheme === 'dark' ? '#3a3a38' : '#e4e4e0'
   const textColor = resolvedTheme === 'dark' ? '#c3c2b7' : '#52514e'
 
-  const { config, invalid } = useMemo(() => {
-    let parsed: unknown
-    try {
-      parsed = JSON.parse(source)
-    } catch {
-      // Incomplete JSON — the fence body is still streaming in.
-      return { config: null, invalid: false }
-    }
-    // Models occasionally reach for pie-flavored field names despite the
-    // skill's schema; map the predictable aliases before validating.
-    if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
-      const obj = parsed as Record<string, unknown>
-      if (obj.x === undefined && typeof obj.label === 'string') obj.x = obj.label
-      if (obj.y === undefined && typeof obj.value === 'string') obj.y = obj.value
-    }
-    const result = blocks.ChartBlockSchema.safeParse(parsed)
-    return result.success
-      ? { config: result.data, invalid: false }
-      : { config: null, invalid: true }
-  }, [source])
+  const { config, invalid } = useMemo(() => parseChartSource(source), [source])
 
   // Complete JSON that fails the schema is a real error — say so instead of
   // showing the streaming placeholder forever.
diff --git a/apps/x/packages/core/src/runtime/assembly/skills/doc-collab/skill.ts b/apps/x/packages/core/src/runtime/assembly/skills/doc-collab/skill.ts
index 27c5dea5..9678df7d 100644
--- a/apps/x/packages/core/src/runtime/assembly/skills/doc-collab/skill.ts
+++ b/apps/x/packages/core/src/runtime/assembly/skills/doc-collab/skill.ts
@@ -224,7 +224,7 @@ Renders a chart from inline data.
 - \`data\` (optional): Array of objects with the data points
 - \`source\` (optional): Relative path to a JSON file containing the data array (alternative to inline data)
 - \`x\` (required): Key name for the x-axis / label field
-- \`y\` (required): Key name for the y-axis / value field
+- \`y\` (required): Key name for the y-axis / value field — or an array of key names to plot several series on one chart (each row then carries one key per series)
 
 ### Table Block
 Renders a styled table from structured data.