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@kindgi/adapter-model-anthropic

npm install @kindgi/adapter-model-anthropic · source

Anthropic ModelProvider for @kindgi/capabilities. Wraps the official @anthropic-ai/sdk client behind the framework's provider-neutral interface and calls the Anthropic Messages API. One provider exposes every model listed in its metadata.models[]; ModelCallInput.model picks the model per call.

Purpose

Section titled “Purpose”

Translate between the framework's ModelCallInput / ModelCallResult and a non-streaming messages.create call:

  • system messages are lifted into the top-level system parameter (several are joined with a blank line). tool messages become tool_result blocks folded into user turns, and assistant toolCalls become tool_use blocks.
  • Tool names are encoded . → __ on send and decoded on receive, because the Messages API rejects dots in tool names (acme.orders.lookup ↔ acme__orders__lookup). Tool ids must not contain a literal __.
  • max_tokens is always sent, since Anthropic requires it: input.maxOutputTokens, else the model's ModelInfo.maxOutputTokens, else 4096. temperature is sent when set, and abortSignal is passed to the request.
  • stop_reason maps end_turn / stop_sequence / pause_turn → stop, max_tokens → length, tool_use → tool-use, refusal → content-filter, anything else → stop.
  • Cost accounting that includes prompt caching. Anthropic reports four counters (input_tokens, output_tokens, cache_creation_input_tokens, cache_read_input_tokens), and costUsd bills each at its own rate: (input × rate + cacheCreation × rate × creationMultiplier + cacheRead × rate × readMultiplier + output × outputRate) / 1000. The multiplier defaults match the 5-minute cache tier (creation 1.25, read 0.1); set promptCacheCreationMultiplier: 2 in a model's cost for the 1-hour tier. usage.promptTokens includes cache writes and reads; usage.cachedTokens reports the cache reads when there are any.

Exports

Section titled “Exports”
  • createAnthropicProvider(options) — returns a ModelProvider whose metadata is options.metadata. invoke() throws when input.model is not one of metadata.models[].name.
  • AnthropicProviderOptions:
    • apiKey: string | (() => string | Promise<string>) — a static key, or a resolver called on every invoke(). The SDK client is cached and rebuilt only when the resolved key changes, so a rotated secret takes effect on the next call. A per-tenant registry can register one provider per tenant whose resolver reads that tenant's secret.
    • metadata — ProviderMetadata whose models[] are AnthropicModelInfo. Caller-supplied, because the API does not report pricing, context windows or features.
    • baseURL? — override the API host (proxy, gateway, region routing).
    • clientOptions? — other @anthropic-ai/sdk client options (timeout, maxRetries, defaultHeaders, fetch, …); apiKey and baseURL are excluded.
    • client? — an injected SDK client, used as-is; apiKey, baseURL and clientOptions are then ignored. Useful in tests.
  • AnthropicModelInfo — ModelInfo whose cost also accepts promptCacheCreationMultiplier? and promptCacheReadMultiplier?.
  • Cost helpers — computeCostUsd(usage, rates), toFrameworkUsage(usage), CostRates, DEFAULT_CACHE_CREATION_MULTIPLIER_5MIN (1.25), DEFAULT_CACHE_READ_MULTIPLIER (0.1).
  • Translation helpers — toAnthropicMessages(messages), toAnthropicTools(tools), fromAnthropicResponse(response), mapStopReason(reason).
  • ModelProvider — type re-export from @kindgi/capabilities.

Example

Section titled “Example”
import { createProviderRegistry } from '@kindgi/capabilities';
import { createAnthropicProvider } from '@kindgi/adapter-model-anthropic';


const anthropic = createAnthropicProvider({
  // Resolved on every call; `readTenantSecret` stands for your secret store lookup.
  apiKey: () => readTenantSecret(tenantId, 'anthropic-api-key'),
  metadata: {
    id: 'anthropic',
    region: 'us-east-1',
    models: [
      {
        name: 'claude-opus-4-7',
        contextWindow: 200_000,
        features: ['tool-use'],
        maxOutputTokens: 8_192,
        // Rates from the provider's published pricing; cache multipliers default to the 5-minute tier.
        cost: { promptUsdPer1kTokens: 0.005, completionUsdPer1kTokens: 0.025 },
      },
    ],
  },
});


const { registry } = createProviderRegistry();
registry.register(tenantId, anthropic);


const result = await anthropic.invoke({
  model: 'claude-opus-4-7',
  messages: [
    { role: 'system', content: 'You are the acme support assistant.' },
    { role: 'user', content: 'Summarise order 1042 in one sentence.' },
  ],
  maxOutputTokens: 256,
});
console.log(result.message.content, result.usage, result.costUsd);

A single-key deployment passes apiKey: process.env.ANTHROPIC_API_KEY (checked for undefined first) instead of a resolver.

Non-goals

Section titled “Non-goals”
  • Streaming. invoke() resolves with the complete response; streaming would need a different ModelProvider interface.
  • Extended thinking. ModelMessage has no thinking field; thinking blocks in responses are dropped.
  • Image inputs. ModelMessage content is text only.
  • Structured output. structuredOutput on ModelCallInput is ignored.
  • Retry logic in the adapter. Retries and timeouts are the SDK client's (clientOptions.maxRetries, clientOptions.timeout).
Section titled “Related”