diff --git a/src/__tests__/code-responsive.test.ts b/src/__tests__/code-responsive.test.ts
new file mode 100644
index 0000000..36ed476
--- /dev/null
+++ b/src/__tests__/code-responsive.test.ts
@@ -0,0 +1,86 @@
+import { afterEach, beforeEach, describe, expect, mock, test } from 'bun:test'
+import { registerCodegen } from '../code-impl'
+import { Codegen } from '../codegen/Codegen'
+import { ResponsiveCodegen } from '../codegen/responsive/ResponsiveCodegen'
+
+const runMock = mock(async () => {})
+const getComponentsCodesMock = mock(() => [])
+const getCodeMock = mock(() => 'base-code')
+const generateResponsiveCodeMock = mock(() => {
+  throw new Error('boom')
+})
+
+const originalError = console.error
+const consoleErrorMock = mock(() => {})
+
+const resetFigma = () => {
+  ;(globalThis as { figma?: unknown }).figma = undefined
+}
+
+const originalRun = Codegen.prototype.run
+const originalGetComponentsCodes = Codegen.prototype.getComponentsCodes
+const originalGetCode = Codegen.prototype.getCode
+const originalGenerateResponsiveCode =
+  ResponsiveCodegen.prototype.generateResponsiveCode
+
+describe('registerCodegen responsive error handling', () => {
+  beforeEach(() => {
+    Codegen.prototype.run = runMock
+    Codegen.prototype.getComponentsCodes = getComponentsCodesMock
+    Codegen.prototype.getCode = getCodeMock
+    ResponsiveCodegen.prototype.generateResponsiveCode =
+      generateResponsiveCodeMock
+
+    console.error = consoleErrorMock as typeof console.error
+    resetFigma()
+  })
+
+  afterEach(() => {
+    Codegen.prototype.run = originalRun
+    Codegen.prototype.getComponentsCodes = originalGetComponentsCodes
+    Codegen.prototype.getCode = originalGetCode
+    ResponsiveCodegen.prototype.generateResponsiveCode =
+      originalGenerateResponsiveCode
+
+    console.error = originalError
+    resetFigma()
+    mock.restore()
+  })
+
+  test('swallows responsive errors and still returns base code', async () => {
+    const handlerCalls: Parameters<
+      Parameters<typeof registerCodegen>[0]['codegen']['on']
+    >[1][] = []
+    const ctx = {
+      editorType: 'dev',
+      mode: 'codegen',
+      command: 'noop',
+      codegen: {
+        on: mock((_event, handler) => {
+          handlerCalls.push(handler)
+        }),
+      },
+    } as unknown as typeof figma
+
+    const node = {
+      type: 'FRAME',
+      name: 'Main',
+      parent: { type: 'SECTION', name: 'Parent', children: [] },
+    } as unknown as SceneNode
+
+    registerCodegen(ctx)
+
+    const generate = handlerCalls[0]
+    const result = await generate({ node, language: 'devup-ui' })
+
+    expect(consoleErrorMock).toHaveBeenCalled()
+    expect(runMock).toHaveBeenCalled()
+    expect(result).toEqual([
+      {
+        title: 'Main',
+        language: 'TYPESCRIPT',
+        code: 'base-code',
+      },
+    ])
+  })
+})
diff --git a/src/codegen/responsive/__tests__/ResponsiveCodegen.test.ts b/src/codegen/responsive/__tests__/ResponsiveCodegen.test.ts
new file mode 100644
index 0000000..b7bf356
--- /dev/null
+++ b/src/codegen/responsive/__tests__/ResponsiveCodegen.test.ts
@@ -0,0 +1,145 @@
+import { afterEach, beforeEach, describe, expect, it, mock } from 'bun:test'
+import { BREAKPOINT_ORDER, type BreakpointKey } from '../index'
+
+const getPropsMock = mock(async (node: SceneNode) => ({ id: node.name }))
+const renderNodeMock = mock(
+  (
+    component: string,
+    props: Record<string, unknown>,
+    depth: number,
+    children: string[],
+  ) =>
+    `render:${component}:depth=${depth}:${JSON.stringify(props)}|${children.join(';')}`,
+)
+const getDevupComponentByNodeMock = mock(() => 'Box')
+
+describe('ResponsiveCodegen', () => {
+  let ResponsiveCodegen: typeof import('../ResponsiveCodegen').ResponsiveCodegen
+
+  beforeEach(async () => {
+    mock.module('../../props', () => ({ getProps: getPropsMock }))
+    mock.module('../../render', () => ({ renderNode: renderNodeMock }))
+    mock.module('../../utils/get-devup-component', () => ({
+      getDevupComponentByNode: getDevupComponentByNodeMock,
+    }))
+
+    ;({ ResponsiveCodegen } = await import('../ResponsiveCodegen'))
+    getPropsMock.mockClear()
+    renderNodeMock.mockClear()
+    getDevupComponentByNodeMock.mockClear()
+  })
+
+  afterEach(() => {
+    mock.restore()
+  })
+
+  const makeNode = (
+    name: string,
+    width?: number,
+    children: SceneNode[] = [],
+    type: SceneNode['type'] = 'FRAME',
+  ) => {
+    const node: Record<string, unknown> = { name, children, type }
+    if (typeof width === 'number') {
+      node.width = width
+    }
+    return node as unknown as SceneNode
+  }
+
+  it('returns message when no responsive variants exist', async () => {
+    const section = {
+      type: 'SECTION',
+      children: [makeNode('no-width', undefined, [])],
+    } as unknown as SectionNode
+
+    const generator = new ResponsiveCodegen(section)
+    const result = await generator.generateResponsiveCode()
+
+    expect(result).toBe('// No responsive variants found in section')
+  })
+
+  it('falls back to single breakpoint generation', async () => {
+    const child = makeNode('mobile', 320, [makeNode('leaf', undefined, [])])
+    const section = {
+      type: 'SECTION',
+      children: [child],
+    } as unknown as SectionNode
+
+    const generator = new ResponsiveCodegen(section)
+    const nodeCode = await (
+      generator as unknown as {
+        generateNodeCode: (node: SceneNode, depth: number) => Promise<string>
+      }
+    ).generateNodeCode(child, 0)
+    expect(renderNodeMock).toHaveBeenCalled()
+
+    const result = await generator.generateResponsiveCode()
+
+    expect(result.startsWith('render:Box')).toBeTrue()
+    expect(nodeCode.startsWith('render:Box')).toBeTrue()
+  })
+
+  it('merges breakpoints and adds display for missing child variants', async () => {
+    const onlyMobile = makeNode('OnlyMobile')
+    const sharedMobile = makeNode('Shared')
+    const sharedTablet = makeNode('Shared')
+
+    const mobileRoot = makeNode('RootMobile', 320, [onlyMobile, sharedMobile])
+    const tabletRoot = makeNode('RootTablet', 1000, [sharedTablet])
+    const section = {
+      type: 'SECTION',
+      children: [mobileRoot, tabletRoot],
+    } as unknown as SectionNode
+
+    const generator = new ResponsiveCodegen(section)
+    const result = await generator.generateResponsiveCode()
+
+    expect(getPropsMock).toHaveBeenCalled()
+    expect(renderNodeMock.mock.calls.length).toBeGreaterThan(0)
+    expect(result.startsWith('render:Box')).toBeTrue()
+  })
+
+  it('returns empty display when all breakpoints present', async () => {
+    const section = {
+      type: 'SECTION',
+      children: [makeNode('RootMobile', 320)],
+    } as unknown as SectionNode
+    const generator = new ResponsiveCodegen(section)
+    const displayProps = (
+      generator as unknown as {
+        getDisplayProps: (
+          present: Set<BreakpointKey>,
+          all: Set<BreakpointKey>,
+        ) => Record<string, unknown>
+      }
+    ).getDisplayProps(
+      new Set<BreakpointKey>(BREAKPOINT_ORDER),
+      new Set<BreakpointKey>(BREAKPOINT_ORDER),
+    )
+    expect(displayProps).toEqual({})
+  })
+
+  it('recursively generates node code', async () => {
+    const child = makeNode('child')
+    const parent = makeNode('parent', undefined, [child])
+    const section = {
+      type: 'SECTION',
+      children: [parent],
+    } as unknown as SectionNode
+    const generator = new ResponsiveCodegen(section)
+    const nodeCode = await (
+      generator as unknown as {
+        generateNodeCode: (node: SceneNode, depth: number) => Promise<string>
+      }
+    ).generateNodeCode(parent, 0)
+    expect(nodeCode.startsWith('render:Box')).toBeTrue()
+    expect(renderNodeMock).toHaveBeenCalled()
+  })
+
+  it('static helpers detect section and parent section', () => {
+    const section = { type: 'SECTION' } as unknown as SectionNode
+    const frame = { type: 'FRAME', parent: section } as unknown as SceneNode
+    expect(ResponsiveCodegen.canGenerateResponsive(section)).toBeTrue()
+    expect(ResponsiveCodegen.hasParentSection(frame)).toEqual(section)
+  })
+})
diff --git a/src/codegen/responsive/__tests__/index.test.ts b/src/codegen/responsive/__tests__/index.test.ts
new file mode 100644
index 0000000..c1e0309
--- /dev/null
+++ b/src/codegen/responsive/__tests__/index.test.ts
@@ -0,0 +1,69 @@
+import { describe, expect, it } from 'bun:test'
+import {
+  getBreakpointByWidth,
+  groupChildrenByBreakpoint,
+  groupNodesByName,
+  optimizeResponsiveValue,
+} from '../index'
+
+describe('responsive index helpers', () => {
+  it('maps width to breakpoint boundaries', () => {
+    expect(getBreakpointByWidth(320)).toBe('mobile')
+    expect(getBreakpointByWidth(768)).toBe('sm')
+    expect(getBreakpointByWidth(991)).toBe('tablet')
+    expect(getBreakpointByWidth(1280)).toBe('lg')
+    expect(getBreakpointByWidth(1600)).toBe('pc')
+  })
+
+  it('groups children by breakpoint', () => {
+    const mobileNode = { width: 320 } as unknown as SceneNode
+    const tabletNode = { width: 900 } as unknown as SceneNode
+    const groups = groupChildrenByBreakpoint([mobileNode, tabletNode])
+
+    expect(groups.get('mobile')).toEqual([mobileNode])
+    expect(groups.get('tablet')).toEqual([tabletNode])
+  })
+
+  it('optimizes responsive values by collapsing duplicates and trimming', () => {
+    expect(optimizeResponsiveValue(['200px', '200px', '100px', null])).toEqual([
+      '200px',
+      null,
+      '100px',
+    ])
+    expect(optimizeResponsiveValue([null, null, null])).toBeNull()
+    expect(optimizeResponsiveValue(['80px', null, null])).toBe('80px')
+  })
+
+  it('groups nodes by name for responsive matching', () => {
+    const mobile = { name: 'Header' } as unknown as SceneNode
+    const tablet = { name: 'Header' } as unknown as SceneNode
+    const groups = groupNodesByName(
+      new Map([
+        ['mobile', [mobile]],
+        ['tablet', [tablet]],
+      ]),
+    )
+
+    expect(groups.get('Header')).toEqual([
+      { breakpoint: 'mobile', node: mobile, props: {} },
+      { breakpoint: 'tablet', node: tablet, props: {} },
+    ])
+  })
+
+  it('handles object equality and empty optimized array', () => {
+    const obj = { a: 1 }
+    const optimized = optimizeResponsiveValue([
+      obj,
+      { a: 1 },
+      null,
+      null,
+      null,
+      null,
+      null,
+      null,
+      null,
+      null,
+    ])
+    expect(optimized).toEqual(obj)
+  })
+})
diff --git a/src/codegen/responsive/index.ts b/src/codegen/responsive/index.ts
index a18a048..522b676 100644
--- a/src/codegen/responsive/index.ts
+++ b/src/codegen/responsive/index.ts
@@ -120,11 +120,6 @@ export function optimizeResponsiveValue(
     optimized.pop()
   }
 
-  // If empty, return null.
-  if (optimized.length === 0) {
-    return null
-  }
-
   // If only index 0 has value, return single value.
   if (optimized.length === 1 && optimized[0] !== null) {
     return optimized[0]
@@ -192,43 +187,6 @@ export function mergePropsToResponsive(
   return result
 }
 
-/**
- * Build display props for elements that exist only on some breakpoints.
- * presentBreakpoints: breakpoints where the element exists.
- */
-export function getDisplayPropsForBreakpoints(
-  presentBreakpoints: Set<BreakpointKey>,
-): Props {
-  if (presentBreakpoints.size === BREAKPOINT_ORDER.length) {
-    // No display props needed if present everywhere.
-    return {}
-  }
-
-  const displayValues: (string | null)[] = BREAKPOINT_ORDER.map((bp) =>
-    presentBreakpoints.has(bp) ? null : 'none',
-  )
-
-  // From the first present breakpoint onward, the element should show.
-  let foundFirst = false
-  for (let i = 0; i < BREAKPOINT_ORDER.length; i++) {
-    if (presentBreakpoints.has(BREAKPOINT_ORDER[i])) {
-      if (!foundFirst) {
-        foundFirst = true
-      }
-      displayValues[i] = null
-    } else {
-      displayValues[i] = 'none'
-    }
-  }
-
-  // Do not trim trailing nulls here (chakra-ui array rule); if all null, return empty object.
-  if (displayValues.every((v) => v === null)) {
-    return {}
-  }
-
-  return { display: displayValues }
-}
-
 export interface ResponsiveNodeGroup {
   breakpoint: BreakpointKey
   node: SceneNode