Port Abstractions behaviors and structured output

[Quim Muntal (qmuntal)]

Summary

• Port meaningful stable .NET Abstractions behaviors and tests for agents, context and history providers, sessions, responses, messages, and compaction. Expose in-memory history helpers and support concurrent session operations after initialization using a per-session lock.
• Support typed non-object structured output with a shared JSON-format wrapper and decoder across OpenAI Chat and Responses (including Foundry), Anthropic, and Gemini, in streaming and non-streaming runs. Keep ForType and explicit response-format semantics unchanged.
• Reconcile API assessments and one-to-one .NET test pairings in the symbol catalog.
• Address review feedback: preserve JSON marshaling of Session values, reject blank compaction state keys at construction, and avoid the AG-UI initialization lock on the existing-ID path.

Validation

• go test -shuffle=on -count=1 ./... (Go 1.26.1, Windows ARM64)
• go vet ./...
• go run github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.14.0 run --new-from-rev=origin/main (0 issues)
• go -C _catalog run ./cmd/symbolmap reconcile -summary -check
• go -C _catalog run ./cmd/symbolmap tests -summary -check

[Copilot]

🟡 Changes recommended

Session serialization compatibility, delayed state-key panics, and global AG-UI lock contention remain unresolved.

3 open findings

• Preserve value-form Session JSON serialization · New
• Validate compaction provider keys at construction · New
• Avoid global mutex on established AG-UI sessions · New

What changed in this PR

Ports stable abstractions behavior, adds concurrency-safe session state, and supports typed non-object structured output across providers.

Changes:

• Adds synchronized session/history and compaction behavior.
• Wraps and decodes non-object structured output consistently.
• Expands behavioral tests and .NET symbol mappings.

File	Description
provider/​openaiprovider/​strict_schema_test.go	Tests explicit schema rejection.
provider/​openaiprovider/​responses.go	Adds wrapped structured output.
provider/​openaiprovider/​chat.go	Adds wrapped structured output.
provider/​openaiprovider/​chat_test.go	Tests structured output end-to-end.
provider/​geminiprovider/​agent.go	Adds wrapped structured output.
provider/​geminiprovider/​agent_test.go	Tests non-object output.
provider/​anthropicprovider/​agent.go	Adds wrapped structured output.
provider/​anthropicprovider/​agent_test.go	Tests non-object output.
provider/​aguiprovider/​agui.go	Synchronizes thread-ID initialization.
provider/​aguiprovider/​agui_test.go	Tests concurrent thread IDs.
message/​message_test.go	Expands source-cloning tests.
examples/​02-agents/​agents/​step18_compaction_pipeline/​main.go	Displays history size.
agent/​value.go	Synchronizes lazy state values.
agent/​structuredoutput_test.go	Tests custom provider formats.
agent/​session.go	Makes session state concurrent.
agent/​session_test.go	Expands state and concurrency tests.
agent/​response_test.go	Ports response behavior tests.
agent/​options.go	Documents structured wrapping.
agent/​history.go	Exposes in-memory history helpers.
agent/​history_test.go	Tests history APIs and behavior.
agent/​harness/​todo/​todo.go	Clones todo snapshots.
agent/​harness/​todo/​todo_test.go	Tests stable todo snapshots.
agent/​format/​jsonformat/​structuredoutput.go	Implements schema wrapping and decoding.
agent/​format/​jsonformat/​encoding_test.go	Tests wrapper constraints and decoding.
agent/​context_test.go	Ports context-provider tests.
agent/​compaction/​provider.go	Serializes per-session compaction.
agent/​compaction/​historyprovider.go	Validates history state keys.
agent/​compaction/​historyprovider_test.go	Expands reducer tests.
agent/​compaction/​compaction_test.go	Tests concurrent compaction.
agent/​agent.go	Clarifies format documentation.
agent/​agent_test.go	Ports agent metadata/invocation tests.
_catalog/​dotnet-go-sdk-symbol-mapping.json	Reconciles APIs and test pairs.

🧠 Review effort: Balanced

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[github-actions]

API consistency review

Result	Scope
aligned	public API / user-visible behavior / examples

Changed Go contract

• agent.Session gained an internal lock (sessionState with sync.RWMutex) so Get/Set/Delete/ServiceID/SetServiceID/marshal/unmarshal are safe for concurrent use after initialization; Session.Get/Set/Delete now panic on blank keys.
• New exported Session.InMemoryHistory(stateKey string) ([]*message.Message, error) and Session.SetInMemoryHistory(stateKey string, messages []*message.Message) error.
• compaction.NewHistoryProvider / compaction.NewContextProvider / agent.NewInMemoryHistoryProvider now panic on blank StateKey; contextProvider gained a per-session mutex around compaction.
• New jsonformat.WrapNonObjectSchema and Format.UnmarshalStructuredOutput, wired into openaiprovider (chat + responses), anthropicprovider, and geminiprovider formatOf/unmarshal so non-object structured-output schemas are transparently wrapped in an object "data" property on the wire and unwrapped on decode; agent.WithStructuredOutput doc updated accordingly.
• aguiprovider.getOrCreateThreadID adds a package-level mutex guarding first-time thread-ID initialization and a nil-session fallback.
• examples/02-agents/agents/step18_compaction_pipeline updated to print in-memory history length using the new Session.InMemoryHistory accessor.

Upstream evidence reviewed

Implementation	Source	Contract checked
.NET	AgentSessionStateBag.cs	Session state bag is explicitly documented and implemented as thread-safe (ConcurrentDictionary), matching Go's new per-session sync.RWMutex guarding Session state.
.NET	AgentSessionExtensions.cs	TryGetInMemoryChatHistory/SetInMemoryChatHistory extension methods are the direct analog of Go's new Session.InMemoryHistory/SetInMemoryHistory; semantics (replace-on-set, state-key default, nil/missing-state handling) line up modulo idiomatic error-return vs. out/exception differences.
.NET	AIAgentStructuredOutput.cs	RunAsync<T> calls StructuredOutputSchemaUtilities.WrapNonObjectSchema on the generated ChatResponseFormat before dispatch and tracks IsWrappedInObject for unwrapping on decode — the same object-wrapping-for-non-object-schema behavior Go now implements via jsonformat.WrapNonObjectSchema/UnmarshalStructuredOutput, applied consistently across providers.

Assessment

The PR is a faithful, well-evidenced port of stable .NET Abstractions behavior: session thread-safety matches the documented ConcurrentDictionary-backed AgentSessionStateBag contract, the new in-memory history accessors mirror AgentSessionExtensions, and the non-object structured-output wrapping mirrors AIAgentStructuredOutput's WrapNonObjectSchema/IsWrappedInObject round trip, applied uniformly across OpenAI (chat + responses), Anthropic, and Gemini providers — consistent with ForType unwrapped local validation being preserved as stated in WithStructuredOutput's updated doc. The new blank-StateKey panics and aguiprovider thread-ID init-lock are internal hardening with no divergent upstream default. No actionable parity issues found; go build ./... succeeds on the PR branch.

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