feat: Pass through data URLs directly and gracefully handle unknown U…

[yxshee]

Summary

Fixes #12547

Error: TypeError: The URL must be of scheme file (ERR_INVALID_URL_SCHEME)

Root Cause

In prompt.ts, the switch statement at line 946 handles URL protocols:

• case "data:" only processes text/plain mime types, then breaks
• For clipboard images (image/png), the condition fails and falls through to case "file:"
• fileURLToPath() is called on a data: URL → crash

Changes

packages/opencode/src/session/prompt.ts

• Added proper handling for non-text data: URLs (images, PDFs) - returns them as-is for the model
• Added default case to prevent silent fall-through for unknown protocols

Why This Happens on Windows

Windows clipboard paste encodes images as data:image/png;base64,... URLs via FileReader.readAsDataURL(). The server-side switch statement wasn't handling this case properly.

Testing

• Paste image from clipboard on Windows 11 - no crash, image attaches correctly
• File drop still works
• File picker still works
• Paste text still works

Checklist

• Minimal fix addressing root cause
• No try-catch band-aids
• Follows existing code patterns

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate Found

PR #12549: fix(desktop): windows clipboard images come thru as data not file
#12549

This PR is directly related to the current PR #12592. Both address the same issue: handling clipboard images on Windows that come through as data: URLs instead of file URLs. PR #12549 appears to be a prior fix for the same problem, so you should check if it's already merged or if it needs to be superseded/combined with PR #12592.

[Copilot]

Pull request overview

Fixes a crash when handling clipboard-pasted images (e.g., Windows 11 data:image/png;base64,...) by preventing data: URLs from falling through to file: handling and by adding a safe fallback for previously-unhandled URL protocols in SessionPrompt.

Changes:

• Pass through non-text/plain data: URL file parts (e.g., images/PDFs) without attempting fileURLToPath().
• Add a default branch in the URL protocol switch to avoid unhandled protocols causing failures/dropped parts.
• Add warning log for unknown protocols (with URL prefix logging).

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[Copilot]

The default-case log includes a prefix of the full URL (part.url.slice(0, 100)), which can leak sensitive user data (e.g., signed URLs/tokens in query strings). Consider logging only the protocol plus a redacted/sanitized identifier (e.g., hostname for http(s), or just url.protocol/mime/length), and avoid logging the URL itself at warn level.

Suggested change

	log.warn("unsupported URL protocol", { protocol: url.protocol, url: part.url.slice(0, 100) })
	log.warn("unsupported URL protocol", {
	protocol: url.protocol,
	mime: part.mime,
	filename: part.filename,
	})

[Copilot]

The default branch labels any non-data:/file: URL as "unsupported" and emits a warn. The codebase can create http: URLs for image parts (see packages/opencode/src/acp/agent.ts where part.uri.startsWith("http:") becomes a file part), and those may be valid to pass through to providers. Consider adding explicit case "http:":/"https:": to pass through without warning, or change the log message/level to reflect "unhandled" rather than "unsupported" to avoid noisy/misleading logs.

[Copilot]

This change introduces new behavior for non-text data: URLs and unknown protocols. There are existing SessionPrompt tests under packages/opencode/test/session/; please add coverage for (1) data:image/png;base64,... parts to ensure they no longer crash/are preserved, and (2) a non-file:/data: URL (e.g., http:) to ensure it’s handled consistently (and not dropped).