Cross-SDK Consistency Review ✅

This PR successfully adds the blob attachment type across all 4 SDK implementations with excellent consistency! The feature is implemented uniformly across Node.js, Python, Go, and .NET.

✅ What's great:

• ✅ Generated types updated in all 4 SDKs
• ✅ Manual type definitions added where needed (Node.js types.ts, Python types.py)
• ✅ Python properly exports BlobAttachment and all attachment types from __init__.py
• ✅ Comprehensive documentation with examples for all 4 languages
• ✅ API naming follows proper language conventions (camelCase vs PascalCase)
• ✅ All READMEs updated consistently

Minor suggestion:

There are a couple of documentation comments that could be updated for completeness (see inline comments), but these are non-blocking polish items. The actual implementation is solid and consistent across all SDKs.

Great work maintaining feature parity! 🎉

Generated by SDK Consistency Review Agent for issue #731 · ◷

SDK Consistency Review: Critical Issues Found ⚠️

Thank you for working on blob attachment support! However, I've identified cross-SDK consistency issues that need to be addressed before this PR can maintain feature parity across all four SDK implementations.

❌ Missing Implementation in Go SDK

The Go SDK's generated types in go/generated_session_events.go are missing blob support:

Current state:

type Attachment struct {
    DisplayName *string `json:"displayName,omitempty"`
    Path *string `json:"path,omitempty"`
    Type AttachmentType `json:"type"`
    FilePath *string `json:"filePath,omitempty"`
    // ... other fields for selection, github_reference
    // ❌ Missing: Data and MIMEType fields
}

const (
    Directory       AttachmentType = "directory"
    File            AttachmentType = "file"
    GithubReference AttachmentType = "github_reference"
    Selection       AttachmentType = "selection"
    // ❌ Missing: Blob constant
)

What's needed:

• Add Data *string and MIMEType *string fields to the Attachment struct
• Add Blob AttachmentType = "blob" constant

❌ Missing Implementation in .NET SDK

The .NET SDK's generated types in dotnet/src/Generated/SessionEvents.cs are missing blob support:

Current state:

[JsonPolymorphic(TypeDiscriminatorPropertyName = "type", ...)]
[JsonDerivedType(typeof(UserMessageDataAttachmentsItemFile), "file")]
[JsonDerivedType(typeof(UserMessageDataAttachmentsItemDirectory), "directory")]
[JsonDerivedType(typeof(UserMessageDataAttachmentsItemSelection), "selection")]
[JsonDerivedType(typeof(UserMessageDataAttachmentsItemGithubReference), "github_reference")]
// ❌ Missing: JsonDerivedType for blob
public partial class UserMessageDataAttachmentsItem { ... }

// ❌ Missing: UserMessageDataAttachmentsItemBlob class entirely

What's needed:

• Create UserMessageDataAttachmentsItemBlob class with Data, MimeType, and DisplayName properties
• Add [JsonDerivedType(typeof(UserMessageDataAttachmentsItemBlob), "blob")] attribute

⚠️ Incomplete Python Generated Types

While the Python SDK has a working implementation via the manual BlobAttachment TypedDict in types.py, the generated types in python/copilot/generated/session_events.py are incomplete:

class AttachmentType(Enum):
    DIRECTORY = "directory"
    FILE = "file"
    GITHUB_REFERENCE = "github_reference"
    SELECTION = "selection"
    # ❌ Missing: BLOB = "blob"

`@dataclass`
class Attachment:
    type: AttachmentType
    # ... existing fields
    # ❌ Missing: data and mime_type fields

🔧 Root Cause

The issue appears to be that the schema used for type generation (session-events.schema.json from @github/copilot) may not have been updated with the blob attachment variant yet, or the type generation script wasn't re-run after the schema update.

📋 Action Items

To bring all SDKs into alignment:

1. Verify schema is up-to-date: Ensure session-events.schema.json from @github/copilot (referenced in copilot-agent-runtime#4249) includes the blob attachment type
2. Re-run type generation: Execute npm run generate:session-types in the nodejs/ directory to regenerate all four language SDKs' types
3. Verify generated output: Confirm that:
   • Go's Attachment struct has Data and MIMEType fields + Blob constant
   • .NET's generated file has UserMessageDataAttachmentsItemBlob class and the corresponding JsonDerivedType
   • Python's generated Attachment dataclass has data and mime_type fields + BLOB enum value

📚 Documentation is Excellent

The documentation updates across all four SDK READMEs and docs/features/image-input.md are comprehensive and show proper examples for all languages—once the generated types are fixed, these examples will work perfectly! ✨

Recommendation: Please update the generated types for Go, .NET, and Python before merging. The manual types in Node.js and Python's types.py are good workarounds, but having consistent generated types across all SDKs is important for long-term maintainability.

Generated by SDK Consistency Review Agent for issue #731 · ◷

CI failures are expected until the runtime PR merges.

✅ Cross-SDK Consistency Review

I've reviewed PR #731 for cross-SDK consistency across all four language implementations (Node.js/TypeScript, Python, Go, and .NET).

Summary: Excellent consistency maintained ✨

This PR successfully adds the blob attachment type to all four SDKs with proper feature parity:

Type Definitions ✅

• Node.js/TypeScript: Manual type added to MessageOptions.attachments union in nodejs/src/types.ts + generated types updated
• Python: BlobAttachment TypedDict added to python/copilot/types.py and properly exported in __init__.py + generated types updated
• Go: Uses generated Attachment struct from generated_session_events.go with Blob AttachmentType constant
• .NET: UserMessageDataAttachmentsItemBlob class generated in dotnet/src/Generated/SessionEvents.cs

API Consistency ✅

All SDKs expose the same three required/optional fields with appropriate naming conventions:

Documentation ✅

• Comprehensive examples added to all four language READMEs
• Detailed feature documentation in docs/features/image-input.md with side-by-side examples
• Updated docs/features/streaming-events.md to mention blob attachments
• Test scenario documentation updated in test/scenarios/prompts/attachments/README.md

No consistency issues found 🎉

The implementation properly accounts for language idioms (camelCase in TS/Python dict keys, PascalCase in Go/C# public APIs) while maintaining semantic equivalence across all SDKs.

Generated by SDK Consistency Review Agent for issue #731 · ◷

✅ Cross-SDK Consistency Review: PASSED

I've completed a comprehensive review of this PR for cross-language SDK consistency. No issues found — this PR maintains excellent feature parity across all four SDK implementations.

Summary

This PR adds support for the blob attachment type (inline base64-encoded data) to complement the existing file attachment type. The implementation is consistent across all languages.

Verification Results

Field Naming Consistency

All SDKs expose the same three fields with language-appropriate naming conventions:

• Type discriminator: "blob" (or copilot.Blob constant in Go)
• Base64 data: data (camelCase) / Data (PascalCase)
• MIME type: mimeType (camelCase) / MIMEType / MimeType (PascalCase)
• Display name (optional): displayName (camelCase) / DisplayName (PascalCase)

Documentation Coverage

✅ All language READMEs updated with blob attachment examples
✅ Comprehensive examples in docs/features/image-input.md for all 4 languages
✅ Event documentation updated in docs/features/streaming-events.md
✅ Test scenario documentation updated

Notes

• As mentioned in the PR description, Go and .NET generated types were already updated via Update @github/copilot to 1.0.4 #796
• Python public API exports properly include all attachment types (BlobAttachment, FileAttachment, DirectoryAttachment, SelectionAttachment, Attachment)
• Examples correctly demonstrate language-specific pointer usage (Go) and type naming (.NET generated classes)

Recommendation: Approve — This PR maintains full cross-SDK feature parity with appropriate language idioms.

Generated by SDK Consistency Review Agent for issue #731 · ◷