An exact provider counter is an implementation of ContextCounter whose CountContext result has CountQualityExactProvider. The interface does not prescribe a provider endpoint or wire shape; the adapter owns those details.

Adapter

type providerCounter struct {
	capability contextcount.CounterCapability
}

func (c providerCounter) CountContext(ctx context.Context, req inference.Request) (contextcount.ContextCount, error) {
	// Send the provider's complete count request and normalize its response.
	return contextcount.ContextCount{
		Model: req.Model.Key(), Quality: contextcount.CountQualityExactProvider,
		InputTokens: 123,
	}, nil
}

func (c providerCounter) CounterCapability() contextcount.CounterCapability { return c.capability }

The placeholder value above is a shape example only; a real adapter must map the provider response and return its actual count. ContextCounterFunc can wrap the function and enforce model and quality consistency.

Trust

Declare whether counting uses the same endpoint or a separate endpoint, the provider identity, security identity, retention posture, tokenizer revision, and exact quality. CompatibleCounter rejects provider, identity, transport, or retention downgrades before policy uses the result.

Source and proof

Run go test ./contextcount.