diff --git a/.changeset/beige-parents-lick.md b/.changeset/beige-parents-lick.md
new file mode 100644
index 0000000000..e2fd26d144
--- /dev/null
+++ b/.changeset/beige-parents-lick.md
@@ -0,0 +1,6 @@
+---
+'@hyperdx/app': patch
+'@hyperdx/common-utils': patch
+---
+
+fix: prevent false "data source not set" error on markdown dashboard tiles
diff --git a/packages/api/src/routers/external-api/v2/utils/__tests__/dashboards.test.ts b/packages/api/src/routers/external-api/v2/utils/__tests__/dashboards.test.ts
new file mode 100644
index 0000000000..46e40ee481
--- /dev/null
+++ b/packages/api/src/routers/external-api/v2/utils/__tests__/dashboards.test.ts
@@ -0,0 +1,77 @@
+import { isBuilderSavedChartConfig } from '@hyperdx/common-utils/dist/guards';
+import { DisplayType } from '@hyperdx/common-utils/dist/types';
+
+import { ConfigTile, convertToInternalTileConfig } from '../dashboards';
+
+function makeMarkdownTile(
+  markdown?: string,
+  overrides: Partial<ConfigTile> = {},
+): ConfigTile {
+  return {
+    id: 'test-id',
+    x: 0,
+    y: 0,
+    w: 12,
+    h: 4,
+    name: 'Text Tile',
+    config: { displayType: 'markdown', markdown },
+    ...overrides,
+  };
+}
+
+describe('convertToInternalTileConfig', () => {
+  describe('markdown tiles', () => {
+    it('sets displayType to Markdown', () => {
+      const result = convertToInternalTileConfig(makeMarkdownTile('# Hello'));
+      expect(result.config).toMatchObject({
+        displayType: DisplayType.Markdown,
+      });
+    });
+
+    it('preserves markdown content', () => {
+      const content = '## Guide\n\nSome instructions here.';
+      const result = convertToInternalTileConfig(makeMarkdownTile(content));
+      if (!isBuilderSavedChartConfig(result.config)) {
+        throw new Error('Expected BuilderSavedChartConfig for markdown tile');
+      }
+      expect(result.config.markdown).toBe(content);
+    });
+
+    it('handles missing markdown content', () => {
+      const result = convertToInternalTileConfig(makeMarkdownTile(undefined));
+      expect(result.config).toMatchObject({
+        displayType: DisplayType.Markdown,
+      });
+    });
+
+    it('preserves tile layout fields', () => {
+      const tile = makeMarkdownTile('Some text', {
+        x: 4,
+        y: 8,
+        w: 24,
+        h: 3,
+        name: 'How to Use',
+      });
+      const result = convertToInternalTileConfig(tile);
+      expect(result.x).toBe(4);
+      expect(result.y).toBe(8);
+      expect(result.w).toBe(24);
+      expect(result.h).toBe(3);
+      // name is picked by convertToInternalTileConfig but not part of the
+      // Tile type — verify it round-trips via the runtime object.
+      expect(result).toHaveProperty('name', 'How to Use');
+    });
+
+    it('does not set a real sourceId on the internal config', () => {
+      // Markdown tiles have source: '' in the internal format to satisfy the
+      // BuilderSavedChartConfig type. The frontend uses displayTypeRequiresSource()
+      // to exclude markdown tiles from "source unset" checks.
+      // See DBDashboardPage isSourceUnset and common-utils/src/guards.ts.
+      const result = convertToInternalTileConfig(makeMarkdownTile('# Hello'));
+      if (!isBuilderSavedChartConfig(result.config)) {
+        throw new Error('Expected BuilderSavedChartConfig for markdown tile');
+      }
+      expect(result.config.source).not.toMatch(/^[a-f0-9]{24}$/); // not a real ObjectId
+    });
+  });
+});
diff --git a/packages/app/src/DBDashboardPage.tsx b/packages/app/src/DBDashboardPage.tsx
index e955dba243..286a51e133 100644
--- a/packages/app/src/DBDashboardPage.tsx
+++ b/packages/app/src/DBDashboardPage.tsx
@@ -25,6 +25,7 @@ import {
   displayTypeSupportsRawSqlAlerts,
 } from '@hyperdx/common-utils/dist/core/utils';
 import {
+  displayTypeRequiresSource,
   isBuilderChartConfig,
   isBuilderSavedChartConfig,
   isRawSqlChartConfig,
@@ -397,6 +398,7 @@ const Tile = forwardRef(
     const isSourceUnset =
       !!chart.config &&
       isBuilderSavedChartConfig(chart.config) &&
+      displayTypeRequiresSource(chart.config.displayType) &&
       !chart.config.source;
 
     useEffect(() => {
diff --git a/packages/common-utils/src/__tests__/guards.test.ts b/packages/common-utils/src/__tests__/guards.test.ts
new file mode 100644
index 0000000000..166465aee1
--- /dev/null
+++ b/packages/common-utils/src/__tests__/guards.test.ts
@@ -0,0 +1,170 @@
+import {
+  displayTypeRequiresSource,
+  isBuilderSavedChartConfig,
+  isRawSqlSavedChartConfig,
+} from '@/guards';
+import { DisplayType } from '@/types';
+
+describe('isRawSqlSavedChartConfig', () => {
+  it('returns true when configType is "sql"', () => {
+    expect(
+      isRawSqlSavedChartConfig({
+        configType: 'sql',
+        displayType: DisplayType.Table,
+        connection: 'conn-id',
+        sqlTemplate: 'SELECT 1',
+      } as any),
+    ).toBe(true);
+  });
+
+  it('returns false for a builder config with no configType', () => {
+    expect(
+      isRawSqlSavedChartConfig({
+        displayType: DisplayType.Line,
+        source: 'src-id',
+        select: [],
+        where: '',
+      } as any),
+    ).toBe(false);
+  });
+
+  it('returns false for a markdown config', () => {
+    expect(
+      isRawSqlSavedChartConfig({
+        displayType: DisplayType.Markdown,
+        markdown: '# Hello',
+        source: '',
+        where: '',
+        select: [],
+      } as any),
+    ).toBe(false);
+  });
+});
+
+describe('isBuilderSavedChartConfig', () => {
+  it('returns true for a standard builder config', () => {
+    expect(
+      isBuilderSavedChartConfig({
+        displayType: DisplayType.Line,
+        source: 'src-id',
+        select: [],
+        where: '',
+      } as any),
+    ).toBe(true);
+  });
+
+  it('returns false for a raw SQL config', () => {
+    expect(
+      isBuilderSavedChartConfig({
+        configType: 'sql',
+        displayType: DisplayType.Table,
+        connection: 'conn-id',
+        sqlTemplate: 'SELECT 1',
+      } as any),
+    ).toBe(false);
+  });
+
+  it('returns true for a markdown tile config', () => {
+    // Markdown tiles are stored as BuilderSavedChartConfig with source: ''
+    // because the type requires a source field. displayTypeRequiresSource()
+    // is the canonical guard for excluding sourceless display types from the
+    // "source unset" check -- see DBDashboardPage isSourceUnset.
+    expect(
+      isBuilderSavedChartConfig({
+        displayType: DisplayType.Markdown,
+        markdown: '# Hello',
+        source: '',
+        where: '',
+        select: [],
+      } as any),
+    ).toBe(true);
+  });
+});
+
+describe('displayTypeRequiresSource', () => {
+  it('returns false for Markdown', () => {
+    expect(displayTypeRequiresSource(DisplayType.Markdown)).toBe(false);
+  });
+
+  it('returns true for Line', () => {
+    expect(displayTypeRequiresSource(DisplayType.Line)).toBe(true);
+  });
+
+  it('returns true for Table', () => {
+    expect(displayTypeRequiresSource(DisplayType.Table)).toBe(true);
+  });
+
+  it('returns true for Search', () => {
+    expect(displayTypeRequiresSource(DisplayType.Search)).toBe(true);
+  });
+
+  it('returns true for StackedBar', () => {
+    expect(displayTypeRequiresSource(DisplayType.StackedBar)).toBe(true);
+  });
+
+  it('returns true for Pie', () => {
+    expect(displayTypeRequiresSource(DisplayType.Pie)).toBe(true);
+  });
+
+  it('returns true for undefined', () => {
+    expect(displayTypeRequiresSource(undefined)).toBe(true);
+  });
+
+  describe('isSourceUnset pattern', () => {
+    // These tests exercise the production isSourceUnset condition used in
+    // DBDashboardPage via the real displayTypeRequiresSource export.
+    function isSourceUnset(config: any): boolean {
+      return (
+        !!config &&
+        isBuilderSavedChartConfig(config) &&
+        displayTypeRequiresSource(config.displayType) &&
+        !config.source
+      );
+    }
+
+    it('does not fire for markdown tiles with empty source', () => {
+      expect(
+        isSourceUnset({
+          displayType: DisplayType.Markdown,
+          markdown: '# Hello',
+          source: '', // stored as '' by convertToInternalTileConfig
+          where: '',
+          select: [],
+        }),
+      ).toBe(false);
+    });
+
+    it('fires for builder tiles with empty source', () => {
+      expect(
+        isSourceUnset({
+          displayType: DisplayType.Line,
+          source: '',
+          select: [],
+          where: '',
+        }),
+      ).toBe(true);
+    });
+
+    it('does not fire for builder tiles with a real source', () => {
+      expect(
+        isSourceUnset({
+          displayType: DisplayType.Line,
+          source: 'abc123',
+          select: [],
+          where: '',
+        }),
+      ).toBe(false);
+    });
+
+    it('does not fire for raw SQL tiles', () => {
+      expect(
+        isSourceUnset({
+          configType: 'sql',
+          displayType: DisplayType.Table,
+          connection: 'conn-id',
+          sqlTemplate: 'SELECT 1',
+        }),
+      ).toBe(false);
+    });
+  });
+});
diff --git a/packages/common-utils/src/guards.ts b/packages/common-utils/src/guards.ts
index 62621db5d0..8efc810923 100644
--- a/packages/common-utils/src/guards.ts
+++ b/packages/common-utils/src/guards.ts
@@ -3,6 +3,7 @@ import {
   BuilderSavedChartConfig,
   ChartConfig,
   ChartConfigWithOptDateRange,
+  DisplayType,
   RawSqlChartConfig,
   RawSqlSavedChartConfig,
   SavedChartConfig,
@@ -31,3 +32,15 @@ export function isBuilderSavedChartConfig(
 ): chartConfig is BuilderSavedChartConfig {
   return !isRawSqlSavedChartConfig(chartConfig);
 }
+
+/**
+ * Returns true when a display type semantically requires a data source to be
+ * configured. Currently Markdown is the only display type that does not need a
+ * source (it renders static content). Add any future sourceless display types
+ * here rather than scattering per-type checks across the codebase.
+ */
+export function displayTypeRequiresSource(
+  displayType: DisplayType | undefined,
+): boolean {
+  return displayType !== DisplayType.Markdown;
+}