fix(ChatDisplay/index.tsx): users are only able to download a protocol (

#17015)

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# Overview
Previously, when users clicked the download button, it created a Python
file even for an empty string.
Now, the system downloads only valid protocols that are not single-line
and must include `def run(`.

Closes AUTH-1064
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## Test Plan and Hands on Testing
- Go to OpentronsAI.
- Generate a protocol and download it. You should see a Python file
containing the protocol.
- Simulate the protocol and get feedback.
- Click Download again, but this time, you should not be able to
download the file if the protocol is invalid.
<!--
Describe your testing of the PR. Emphasize testing not reflected in the
code. Attach protocols, logs, screenshots and any other assets that
support your testing.
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## Changelog
- Modified the functionality of the Download button to ensure only valid
protocols can be downloaded.

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end user. Give careful thought and clear documentation to breaking
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## Review requests
Look at the section `Test Plan and Hands on Testing`
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## Risk assessment
Low
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opentrons-ai-client/src/molecules/ChatDisplay/__tests__/ChatDisplay.test.tsx

@@ -93,6 +93,12 @@ describe('ChatDisplay', () => {
   })
 
   it('should call trackEvent when download button is clicked', () => {
+    props.chat = {
+      ...props.chat,
+      role: 'assistant',
+      reply:
+        '```python\ndef run(protocol):\n    print("hello")\n print("protocol")\n return True\n```',
+    }
     URL.createObjectURL = vi.fn()
     window.URL.revokeObjectURL = vi.fn()
     HTMLAnchorElement.prototype.click = vi.fn()
@@ -110,6 +116,24 @@ describe('ChatDisplay', () => {
     })
   })
 
+  it('should not call trackEvent when download button is clicked', () => {
+    URL.createObjectURL = vi.fn()
+    window.URL.revokeObjectURL = vi.fn()
+    HTMLAnchorElement.prototype.click = vi.fn()
+
+    render(props)
+    // eslint-disable-next-line testing-library/no-node-access, @typescript-eslint/non-nullable-type-assertion-style
+    const downloadPath = document.querySelector(
+      '[aria-roledescription="download"]'
+    ) as Element
+    fireEvent.click(downloadPath)
+
+    expect(mockUseTrackEvent).not.toHaveBeenCalledWith({
+      name: 'download-protocol',
+      properties: {},
+    })
+  })
+
   it('should call trackEvent when copy button is clicked', async () => {
     Object.defineProperty(navigator, 'clipboard', {
       value: {

opentrons-ai-client/src/molecules/ChatDisplay/index.tsx

@@ -106,7 +106,18 @@ export function ChatDisplay({ chat, chatId }: ChatDisplayProps): JSX.Element {
 
   const handleFileDownload = (): void => {
     const lastCodeBlock = document.querySelector(`#${chatId}`)
-    const code = lastCodeBlock?.textContent ?? ''
+    const code = lastCodeBlock?.textContent?.trim() ?? ''
+    // Don't proceed if code is empty, no need to download as a python file
+    if (!code) {
+      return
+    }
+    // Make sure python protocol is valid
+    const hasRunFunction = code.includes('def run(')
+    const numberOfLines = code.split('\n').length
+    if (!hasRunFunction || numberOfLines <= 3) {
+      return
+    }
+
     const blobParts: BlobPart[] = [code]
 
     const file = new File(blobParts, 'OpentronsAI.py', { type: 'text/python' })