Support Image Content Result

[KamToHung]

WIP

Summary by Sourcery

Add structured content support for tool responses, including images and audio, by introducing a Content interface and a chain of response handlers that produce unified CallToolResult objects instead of raw strings.

New Features:

• Introduce a Content interface with implementations for text, image, and audio content types
• Implement a ResponseHandlerChain with ImageHandler and TextHandler to process HTTP responses into CallToolResult
• Add NewTextContent, NewImageContent, and NewAudioContent constructors for creating content items

Enhancements:

• Change executeTool to return a CallToolResult and delegate response processing to the handler chain
• Update SSE and streamable handlers to send structured CallToolResult directly instead of wrapping raw text
• Define content type constants (text, image, audio) and implement GetType methods on content structs

[sourcery-ai]

Reviewer's Guide

This PR refactors the content model to support text, image, and audio results via a Content interface, integrates a response handler chain for HTTP responses, and updates tool execution and streaming endpoints to work with the new mcp.CallToolResult structure.

File-Level Changes

Change	Details	Files
Introduce Content interface and multiple content types	Define Content interface with GetType method Add TextContent, ImageContent, AudioContent structs Implement GetType for each struct Add content-type constants	pkg/mcp/types.go pkg/mcp/cnst.go
Refactor executeTool to return CallToolResult	Change signature to return *mcp.CallToolResult Replace processResponse with ResponseHandlerChain.Handle Adjust error return values	internal/core/tool.go
Streamline SSE and streaming endpoints to use CallToolResult directly	Remove manual wrapping of text result into CallToolResult Pass result directly to sendSuccessResponse	internal/core/sse.go internal/core/streamable.go
Implement response handler chain for HTTP responses	Add BaseHandler, ImageHandler, TextHandler implementations Chain handlers to select by Content-Type header Embed handlers to produce CallToolResult	internal/core/handler.go
Add helper constructors for content and tool results	Create NewTextContent, NewImageContent, NewAudioContent functions Add NewCallToolResult factory	pkg/mcp/tools.go

Possibly linked issues

• #0: The PR adds support for image and other non-text content types in tool results by introducing content interfaces and handlers.

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[sourcery-ai]

Hey @KamToHung - I've reviewed your changes - here's some feedback:

• In ImageHandler.Handle, populate ImageContent.MimeType using resp.Header.Get("Content-Type") so the client knows the actual MIME type instead of leaving it blank.
• Since you’ve defined AudioContent in the types, consider adding an AudioHandler in the ResponseHandlerChain to properly handle audio/* responses instead of falling back to the text handler.
• handler.go calls renderTemplate but never defines or imports it—either wire in the correct function from the template package (e.g., template.Render) or provide a local implementation.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Documentation: all looks good

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[KamToHung]

PTAL

[iFurySt]

PTAL

ready for review?

[KamToHung]

PTAL

ready for review?

Yes, please take a look if it meet the requirements

[iFurySt]

are these funcs currently unused?

[iFurySt]

@KamToHung I've just adjusted this PR a bit. feel free to take a look :)

[iFurySt]

everything else looks good to me. let me know if you're okay, I'll merge it.

[KamToHung]

everything else looks good to me. let me know if you're okay, I'll merge it.

I made some changes, please take a look~

[iFurySt]

everything else looks good to me. let me know if you're okay, I'll merge it.

I made some changes, please take a look~

LGTM! could you please resolve conflicts? i'll merge it after they're resolved.

[KamToHung]

everything else looks good to me. let me know if you're okay, I'll merge it.

I made some changes, please take a look~

LGTM! could you please resolve conflicts? i'll merge it after they're resolved.

PTAL

[iFurySt]

LGTM!Thanks!