Jacob Alber 59b6e1f6e0 feat: introduce OutputTag, Futures, and tag-aware WorkflowBuilder API ...

Phase 2 of the .NET Workflows outputs overhaul. Additive code change
only - no observable runtime behavior change. The runner still uses the
legacy bypass for AgentResponse / AgentResponseUpdate payloads, and the
new `Futures.EnableAgentResponseOutputTaggingAndFiltering` flag defaults
to false. Phase 3 will wire the flag into the runner; this commit only
introduces the types and the builder API.

New public surface:
* `OutputTag` (readonly struct): wraps a string Value with ordinal
  equality (IEquatable, GetHashCode, == / !=) so it can participate as a
  HashSet element. Internal ctor closes the set. One public singleton:
  `OutputTag.Intermediate`. Terminal / regular outputs carry no tag
  (empty Tags set). JSON-serialized as a bare string via
  [JsonConverter(typeof(OutputTagJsonConverter))], with the converter
  rehydrating to the well-known singleton on read.
* `Futures` (static class): hosts opt-in pre-GA behavior switches.
  First flag is `EnableAgentResponseOutputTaggingAndFiltering`; XML doc
  captures the v2.0.0 obsoletion / v3.0.0 removal lifecycle.
* `WorkflowOutputEvent.Tags`: `HashSet<OutputTag>` exposed directly
  (concrete collection, matches the JSON-serialization convention used
  for `WorkflowInfo.OutputExecutorIds`). Never null; empty for legacy /
  terminal events. New ctors take a single `OutputTag` or
  `IEnumerable<OutputTag>?`; the existing (data, executorId) ctor
  remains and produces an untagged event. `HasTag(OutputTag)` helper.
  `AgentResponseEvent` and `AgentResponseUpdateEvent` gain matching
  tag-accepting ctors forwarding to the base.
* `WorkflowOutputEventExtensions.IsIntermediate(this WorkflowOutputEvent)`:
  extension method returning `evt.HasTag(OutputTag.Intermediate)`. The
  preferred way to ask "is this an intermediate output?" without
  reaching into the Tags set.
* `WorkflowBuilder.WithOutputFrom(IEnumerable<ExecutorBinding>, OutputTag)`
  and `WorkflowBuilder.WithOutputFrom(ExecutorBinding, OutputTag)`:
  forward-looking tagged overloads. The IEnumerable form is the primary
  tagged surface; the single-executor form is a convenience for the
  common one-executor case. Currently usable for the
  `OutputTag.Intermediate` singleton; will become the primary surface
  once the `OutputTag` constructor is opened to user-defined tags in
  a future release. Callers in this release should prefer the
  intent-specific `WithIntermediateOutputFrom` extension for the
  intermediate case. Tags accumulate across repeated calls; same tag
  repeated dedupes via the HashSet.
* `WorkflowBuilderExtensions.WithIntermediateOutputFrom(this WorkflowBuilder, IEnumerable<ExecutorBinding>)`:
  helper that forwards to `WithOutputFrom(executors, OutputTag.Intermediate)`.
  Takes an IEnumerable (matching the tagged WithOutputFrom shape) -
  callers pass collection literals: `builder.WithIntermediateOutputFrom([a, b])`.
  XML doc remarks call out the Futures-flag interaction and the
  AIAgent-payload forwarding contract.

Internal shape changes:
* `WorkflowBuilder._outputExecutors`: HashSet<string> -> Dictionary<
  string, HashSet<OutputTag>>. The value set is empty for executors
  designated only via the untagged WithOutputFrom; contains Intermediate
  (and possibly future tags) otherwise.
* `Workflow.OutputExecutors`: HashSet<string> -> Dictionary<string,
  HashSet<OutputTag>>.
* `OutputFilter.CanOutput`: `Contains(id)` -> `ContainsKey(id)`.
* `WorkflowInfo.OutputExecutorIds`: HashSet<string> -> Dictionary<
  string, HashSet<OutputTag>>, with a custom JsonConverter that reads
  both the new map shape (`{id: ["intermediate", ...]}`) and the legacy
  array shape (`[id1, id2]`, where each id is treated as an untagged
  output). Always writes the map shape. IsMatch updated to compare
  per-id tag sets.

Tests landing in this commit (per the test-with-feature principle):
* `OutputTagTests.cs` (6 tests): KnownValues, EqualityIsOrdinalOnValue,
  DefaultStructValueIsDistinct (default(OutputTag) does not collide
  with the Intermediate singleton in a HashSet),
  GetHashCodeMatchesEquals, JsonConverter_RoundtripsValueAsString,
  ConstructorIsInternal (reflection-based assertion that the (string)
  ctor is `internal`).
* `WorkflowBuilderTests.cs` adds 7 new tests pinning the builder
  API contract: RegistersWithEmptyTagSet, AddsIntermediateTag,
  MultipleExecutorsAllUntagged, ThenIntermediate_AccumulatesTags,
  RepeatedDedupes, OnlyRegistersWithoutPriorWithOutputFrom,
  TracksExecutorBinding.
* `BackwardsCompatibility/JsonCheckpointSerializationTests.cs`
  (new folder + file, 5 tests): event-level ctor contract tests
  (single-tag, no-tag, multi-tag — the last with a custom tag);
  IsIntermediate() asserted; load-bearing JSON BC tests for
  `WorkflowInfo.OutputExecutorIds` -
  `WorkflowOutputExecutorsReadsLegacyArrayShape` (legacy ids map to
  empty tag sets) and `WorkflowOutputExecutorsWritesMapShape`.

The plan's three JSON round-trip tests for `WorkflowOutputEvent.Tags`
were dropped: `WorkflowEvent` is not currently a serialized checkpoint
shape (see the comment in WorkflowsJsonUtilities.cs about events not
being persisted), so there is no real back-compat surface to pin
through JSON. They are substituted with in-process ctor/property
round-trip tests that exercise the `Tags` / `HasTag` / `IsIntermediate`
contract.

Validation: full `Microsoft.Agents.AI.Workflows.UnitTests` suite runs
green on net10.0 (565 passing, 0 failing). Core library builds clean
on net472, netstandard2.0, net8.0, net9.0, and net10.0. Test project
builds clean on net472 + net10.0.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

59b6e1f6e0 · 2026-05-28 16:44:08 -04:00

History

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JsonCheckpointSerializationTests.cs

feat: introduce OutputTag, Futures, and tag-aware WorkflowBuilder API

2026-05-28 16:44:08 -04:00