[Techsynx]

Fixes #3805

In examples/snippets/servers/images.py, the create_thumbnail tool previously returned Image(data=img.tobytes(), format="png"). Pillow's tobytes() produces raw uncompressed RGB pixel bytes lacking PNG file headers, chunks, and compression, causing downstream clients that attempt to decode the data URL (data:image/png;base64,...) to fail with UnidentifiedImageError or invalid image decode errors.

This PR encodes the resized image into a valid in-memory PNG stream via io.BytesIO() and img.save(buffer, format="PNG"), returning true PNG bytes. An integration test has also been added in tests/server/mcpserver/test_integration.py to verify valid PNG container headers and correct thumbnail dimensions.

Motivation and Context

Fixes #3805. Clients calling create_thumbnail expect valid PNG encoded bytes as indicated by format="png".

How Has This Been Tested?

• Added test_images_thumbnail to tests/server/mcpserver/test_integration.py.
• Tested locally with uv run pytest tests/server/mcpserver/test_integration.py -v (11 passed).
• Formatted and linted with uv run ruff check and uv run ruff format.

Breaking Changes

No breaking changes. Only fixes erroneous encoding in the example snippet.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I am assigned to the linked issue (or it is labeled help wanted, or I'm a maintainer)
• I have disclosed any AI assistance and can explain the change in my own words
• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

Awaiting issue assignment on #3805 to pass intake gate verification.

[github-actions]

This PR has been closed automatically. This repo only keeps pull requests open when they come from a maintainer, or from a contributor a maintainer has assigned to the linked issue, and you aren't currently assigned to #3805.

If a maintainer assigns you to #3805, this PR reopens on its own and there's nothing more you need to do here. Assignment is a maintainer call based on capacity; comments that only ask to be assigned don't factor in. What does help is engaging on the issue itself by confirming the repro, explaining why it matters for your use case, or describing the approach you'd take.

You're welcome to keep pushing commits here (just avoid force-pushing, since GitHub can't reopen a rewritten branch), but that on its own won't get the PR reviewed or the issue assigned, and realistically most auto-closed PRs stay closed. There's no need to open a new PR either way.

CONTRIBUTING.md has the full reasoning, but in short:

• We're a small team with very little capacity to review community PRs right now.
• Many recent PRs are AI-generated with little human review, and reviewing one carefully still costs a maintainer as much time as it ever did. A well-described issue is usually more useful to us than the code.

Maintainers: reopen, remove missing-issue-link, or add bypass-issue-check to override.