Data Model: Extensible Activity Output Converters

Output Binding

Existing Output/Output<T> binding model with one new optional relationship:

Converter: zero or one Converter Configuration
Existing memory reference remains the destination identity
Native output type remains T or object for untyped outputs

Validation:

Converter configuration requires a resolvable destination.
No configuration preserves existing serialization and behavior.

Converter Configuration

Id: required non-empty Converter ID
Settings: optional JSON object, cloned when persisted or invoked

Serialization:

{
  "typeName": "String",
  "memoryReference": {
    "id": "resultVariable"
  },
  "converter": {
    "id": "sample.to-text",
    "settings": {
      "format": "compact"
    }
  }
}

Output Converter Registration

Descriptor: immutable Converter Descriptor
ServiceKey: exact Converter ID used for keyed DI resolution
ServiceLifetime: transient, scoped, or singleton registration lifetime

Uniqueness:

Exact ordinal IDs are unique.
IDs differing only by case are also prohibited.

Converter Descriptor

Id: stable semantic identity
SourceType: supported source CLR type
ResultType: declared result CLR type
DisplayName: discoverable display text
Description: optional discoverable description
SettingsSchema: optional cloned JSON Schema

API projection replaces CLR types with registered aliases or safe type names and omits service registration data.

Output Conversion Context

Value: non-null native Activity Output
SourceType: declared Activity Output type
DestinationType: resolved declared destination type
Settings: immutable/cloned JSON settings

The context has no workflow execution object or service provider.

Destination

Id: memory-reference or workflow-output identity
Type: resolved CLR type
AllowsNull: true for reference types and Nullable<T>, false for other value types
Kind: variable or workflow output

Definition resolution walks the nearest variable-container scope and then workflow outputs. Runtime resolution uses declared memory-block metadata.

Output Conversion Error

ConverterId
Stage: Resolution, SettingsValidation, SourceCompatibility, Invocation, or ResultValidation
ActivityId
ActivityType
OutputName
DestinationId
SourceTypeName
DestinationTypeName
InnerException: optional originating converter exception

Safe fields are copied to persisted exception metadata. Native values and settings are never included.

State transitions

Unconfigured Binding
  └─ assign native value using existing path

Configured Binding
  ├─ record native output
  ├─ native null → validate destination nullability → write null
  └─ non-null
      ├─ resolve registration and destination
      ├─ validate source, destination, and settings
      ├─ invoke converter
      ├─ validate result and nullability
      ├─ success → write Bound Value
      └─ failure → fault activity; destination unchanged

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