Change the way that uploaded images are shown; remove base64 strings (Gray Screen Fix)

[daniel-lxs]

Problem

Webview URIs in frontend caused memory efficiency, but broke image visibility for OpenRouter and other providers.

Solution

Store base64 data URLs directly in backend messages when first received from frontend:

• Frontend: webview URIs (memory efficient) ✅
• Backend: base64 in messages (instant API calls) ✅
• Conversion: One-time only when storing ✅

Key Changes

• Add normalizeImageRefsToDataUrls() for webview URI → base64 conversion
• Update Task.ts to store base64 directly in backend messages
• Security: Fix ReDoS and host injection vulnerabilities
• Tests: Complete coverage with 5/5 unit tests

Performance

• Before: Convert webview URI → base64 on every API call
• After: Use pre-stored base64 (zero conversion overhead)

Fixes image visibility while maintaining webview memory efficiency goals.

---

Important

This PR optimizes image handling by storing base64 data URLs in backend messages, improving performance and security, and includes comprehensive tests.

• Behavior:
  • Store base64 data URLs in backend messages for images, improving API call efficiency.
  • Convert webview URIs to base64 once during storage using normalizeImageRefsToDataUrls().
  • Handle pasted and dropped images by saving them as temporary files and converting to webview URIs.
• Security:
  • Fix ReDoS and host injection vulnerabilities.
  • Filter out base64 data URIs from rendering in Thumbnails.
• Performance:
  • Avoid repeated conversions by caching base64 data URLs in image-cache.ts.
  • Reduce memory usage by not storing base64 in frontend state.
• Components:
  • Update ChatTextArea.tsx and ChatView.tsx to handle image uploads and conversions.
  • Modify Thumbnails.tsx to exclude base64 images from rendering.
• Tests:
  • Add tests for image handling in image-handler.spec.ts and imageDataUrl.spec.ts.
  • Ensure Thumbnails component only renders safe image URIs in Thumbnails.spec.tsx.

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[hannesrudolph]

Images included with a message sent to the chatview are not showing up in the chatview. There was an image attached to this message that is not showing.

[roomote]

Critical Issue Found

This PR introduces a critical bug that breaks image display in the chat view:

Issue: Images stored in backend messages are converted to base64 data URLs (via normalizeImageRefsToDataUrls() in Task.ts), but the frontend's Thumbnails component filters out all base64 data URIs. This causes images attached to messages to never render.

Root cause: The PR's approach stores base64 in ClineMessage.images[] for API calls, but doesn't convert them back to webview URIs when the frontend needs to display them. The Thumbnails component (line 40) explicitly filters !i.startsWith("data:"), so all base64 images are rejected.

Impact: This matches the exact bug reported by @hannesrudolph - images included with messages are not showing up in the chatview.

TODO

• Fix image display: Backend needs to store BOTH base64 (for API) AND webview URI (for frontend display) in messages, OR provide a conversion mechanism to regenerate webview URIs from stored file paths when displaying messages

_{Mention @roomote in a comment to trigger your PR Fixer agent and make changes to this pull request.}

[roomote]

Critical bug: Images stored in ClineMessage.images[] are now base64 data URLs (after normalizeImageRefsToDataUrls conversion), but the frontend's Thumbnails component filters out all base64 data URIs (line 40 of Thumbnails.tsx). This means images attached to messages will never render in the chat view. The PR converts webview URIs to base64 for backend storage but doesn't provide a mechanism to convert them back to webview URIs when displaying messages in the frontend. This breaks the core functionality described in the user's report: "Images included with a message sent to the chatview are not showing up."

[roomote]

The comment states "No caching is implemented" but line 98 still calls setImageBase64ForPath(filePath, dataUrl) which caches the reverse mapping. The comment should be updated to clarify that while forward caching (base64ToFilePathCache) was removed, reverse caching for image-cache lookups is still performed.