Function: createCapability()#

function createCapability<TValue>(): <TName>(name) => Capability<TValue, TName>;

Defined in: packages/ai/src/activities/chat/middleware/capabilities.ts:114

Create a capability. Returns a hybrid handle that destructures to [get, provide] and is itself the identity for requires/provides.

Curried so the value type is supplied explicitly while the name literal is INFERRED from the argument: createCapability<T>()('name'). (A single call createCapability<T>('name') cannot work — supplying T explicitly stops TypeScript inferring the name, collapsing it to string and defeating the compile-time coverage check that keys on the literal name.)

Type Parameters#

TValue#

TValue = unknown

Returns#

<TName>(name): Capability<TValue, TName>;

Type Parameters#

TName#

TName extends string

Parameters#

name#

TName

Returns#

Capability<TValue, TName>

Example#

const counterCapability = createCapability<{ value: number }>()('counter')
const [getCounter, provideCounter] = counterCapability

const withCounter = defineChatMiddleware({
  name: 'counter',
  provides: [counterCapability],
  setup(ctx) { provideCounter(ctx, { value: 0 }) },
})

const readsCounter = defineChatMiddleware({
  name: 'reads-counter',
  requires: [counterCapability],
  onChunk(ctx) { getCounter(ctx).value++ },
})

chat({ adapter, messages, middleware: [withCounter, readsCounter] })

Remarks#

Capability names must be unique across your app: compile-time coverage tracking keys on the name literal (runtime keys on reference).