[mmporong]

Summary

repo:// repository content resources returned every application/* response as text, so binary files served as application/octet-stream (PDFs, archives, etc.) came back as corrupted text. This PR returns only text-based types as text and everything else as a blob.

Why

No existing issue. In RepositoryResourceContentsHandler the response type switch is case strings.HasPrefix(mimeType, "text"), strings.HasPrefix(mimeType, "application"):. raw.githubusercontent.com serves binary files with Content-Type: application/octet-stream (checked with curl -sI on a PDF in mozilla/pdf.js and a .tar.xz in python/cpython), while text files come back as text/plain; charset=utf-8. So repo://owner/repo/contents/file.pdf returned the bytes in Text. Invalid UTF-8 is replaced with U+FFFD when the result is JSON-encoded, so the original file cannot be recovered. get_file_contents already classifies content with an allow-list of text types.

What changed

• pkg/github/repository_resource.go: add isTextMIMEType. text/* stays text. Under application/, only application/json, application/xml, application/javascript, application/*+json and application/*+xml are text (the same set get_file_contents uses, plus application/javascript); other application/* types such as application/octet-stream, application/pdf and application/zip are returned as Blob. Other top-level types keep their previous handling (e.g. image/svg+xml stays a blob). A Content-Type with a malformed parameter (e.g. text/plain; charset) is still classified by its media type, as before.
• pkg/github/repository_resource_test.go: add Test_repositoryResourceContentsHandler_ApplicationTypes with eight cases: octet-stream, pdf and zip come back as blobs; application/json; charset=utf-8, application/xml, application/vnd.api+json and text/plain; charset come back as text; image/svg+xml stays a blob. On main the three binary cases fail (Should be empty, but was %PDF-1.4...) and the other five pass; with this change all eight pass.

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

No tool changes; the repo:// resource read behavior changed: binary application/* files are returned in blob instead of text.

Prompts tested (tool changes only)

• Not applicable (no tool changes); covered by the unit tests above.

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test

Lint: ran the same checks as script/lint directly rather than the script itself: gofmt -l is clean and golangci-lint run ./... with v2.14.0 (the version pinned in script/lint) reports 0 issues. Tests: go test ./pkg/github/ and go vet ./pkg/github/ pass with Go 1.27.3; the full ./script/test (go test -race ./...) was not run.

Docs

• Not needed
• Updated (README / docs / examples)

AI assistance: this change was prepared with Claude (claude-opus-5-5), which found the bug, wrote the fix and tests, ran the checks, and drafted this description.