Port .NET skill and workflow fixes

[Quim Muntal (qmuntal)]

Summary

• Port .NET: Fix YAML block scalar parsing for file skills agent-framework#5610: parse YAML block scalar values in file skill frontmatter.
• Port .NET: feat: Implement message filtering to exclude non-portable content typ… agent-framework#5410: filter hosted-agent response messages before forwarding them through workflows.
• Strip message-level raw provider representations while preserving portable content and content-level raw data.

Validation

• go test ./agent/skills/fsskills
• go test ./agent/skills
• go test ./agent/hosting/workflowhosting -run 'TestHostedAgent_(FiltersNonPortableContentFromForwardedResponseMessages|StripsRawRepresentationFromForwardedResponseMessages|PreservesForwardableContentInMixedForwardedResponseMessages|DropsResponseMessagesWithOnlyNonPortableContent)$' -count=1 -timeout=30s -v
• go test ./agent/hosting/workflowhosting -count=1 -timeout=60s

[Copilot]

Pull request overview

This PR ports upstream fixes into the Go agent framework to improve (1) file-skill frontmatter parsing for YAML block scalars and (2) hosted-agent message forwarding through workflows by filtering out non-portable/provider-artifact content and stripping message-level raw provider representations.

Changes:

• Extend fsskills frontmatter parsing to support YAML block scalar values (|, >) including basic chomping indicators.
• Filter hosted-agent response messages before forwarding through workflows, keeping only forwardable content types and removing Message.RawRepresentation.
• Add targeted unit tests covering block-scalar parsing and workflow-forwarding filtering behavior.

Show a summary per file

File	Description
agent/skills/fsskills/source.go	Adds block-scalar parsing support for YAML frontmatter values.
agent/skills/fsskills/source_test.go	Adds tests validating multiline block scalar parsing and chomping indicators.
agent/hosting/workflowhosting/workflow.go	Filters forwarded response messages to avoid non-portable/provider-artifact content and strips message-level raw representations.
agent/hosting/workflowhosting/workflow_test.go	Adds tests ensuring forwarded messages are filtered/stripped as intended.

Copilot's findings

Tip

Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

• Files reviewed: 4/4 changed files
• Comments generated: 1

[github-actions]

Cross-repo parity review

Reviewer: API Consistency Agent | Upstream ref: microsoft/agent-framework @ f25e81701

---

✅ Message forwarding filter (agent/hosting/workflowhosting/workflow.go)

The Go filterForwardableMessages / filterForwardableContents implementation is semantically aligned with the upstream .NET AIAgentHostExecutor.FilterForwardableMessages in dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/AIAgentHostExecutor.cs:

Aspect	.NET	Go
Allowlisted content types	TextContent, DataContent, UriContent, FunctionCallContent, FunctionResultContent, ToolApprovalRequest/ResponseContent, HostedFileContent, ErrorContent	Same nine types (mapped to Go equivalents)
Message-level RawRepresentation	Stripped (new object constructed without it)	Stripped (Clone() then nil)
Content-level RawRepresentation	Preserved (content items are shared refs)	Preserved (same, confirmed by TestHostedAgent_StripsRawRepresentation...)
Messages with zero forwardable content	Dropped entirely	Dropped entirely

No parity concern here.

---

⚠️ Folded YAML scalar paragraph-break handling (agent/skills/fsskills/source.go)

The upstream .NET ParseYamlScalarValue in AgentFileSkillsSource.cs handles the folded style (>) as:

string.Join(" ", normalizedLines.Where(line => line.Length > 0))

Blank lines are silently discarded — the output is a single space-joined string with no paragraph breaks.

The Go foldYamlLines does something different: blank lines between non-blank lines are converted to \n characters in the output, so this input:

description: >
  First paragraph line one
  line two

  Second paragraph.

produces "First paragraph line one line two\nSecond paragraph." in Go, but would produce "First paragraph line one line two Second paragraph." in .NET.

TestFileSource_FoldedScalarDescription_PreservesParagraphBreaks exercises and documents this divergence.

Note: The Go behaviour is arguably more correct per the YAML 1.2 specification (blank lines in folded blocks should become literal newlines). However, this is a real cross-SDK behavioural difference: a skill whose description uses multi-paragraph folded syntax will produce different values in Go vs. .NET, which could affect how the description appears in system prompts.

Suggestion: Please check whether upstream microsoft/agent-framework#5610 intended to add paragraph-break support for the folded style, or whether the .NET implementation intentionally simplified it. If the .NET behaviour is intentional (e.g., to keep descriptions as a single sentence regardless of author formatting), the Go implementation should align. If the Go behaviour is considered the correct fix, upstream .NET (AgentFileSkillsSource.cs) should receive the same fix for consistency.

Generated by Go API Consistency Review Agent for issue #126 · ● 1.2M · ◷