CapabilityHost

Collects capabilities and exposes a unified interface for any LLM backend.

Usage:

const host = new CapabilityHost()
  .use(new ExtractionCapability({ ... }))
  .use(new ExtractionCapability({ schema }))
  .use(new GuardrailCapability(policies));

// For Gemini Live:
const tools = toGeminiDeclarations(host.getAllTools());
const prompt = host.getSystemPrompt(basePrompt);

// For AI SDK:
const tools = toAISDKTools(host.getAllTools());
streamText({ system: prompt, tools });

Constructors

Constructor

new CapabilityHost(): CapabilityHost;

Returns

CapabilityHost

Accessors

capabilityCount

Get Signature

get capabilityCount(): number;

Number of registered capabilities.

Returns

number

needsReconfigure

Get Signature

get needsReconfigure(): boolean;

True if tools or prompt changed since last markConfigured() call.

Returns

boolean

Methods

addTools()

addTools(tools): this;

Add regular tools not managed by any capability.

Parameters

Parameter	Type
`tools`	`ToolDeclaration`<`unknown`, `unknown`>[]

Returns

this

getAllTools()

getAllTools(): ToolDeclaration<unknown, unknown>[];

Collect all tools from all capabilities + regular tools.

Deduplicates by name — capability-provided tools take priority over regular (agent-level) tools. This prevents duplicate function declarations that providers like Gemini Live reject.

Returns

ToolDeclaration<unknown, unknown>[]

getSystemPrompt()

getSystemPrompt(basePrompt?): string;

Build complete system prompt from base prompt + all capability sections. Sections are ordered by role priority.

Parameters

Parameter	Type
`basePrompt?`	`string`

Returns

string

markConfigured()

markConfigured(): void;

Mark the current state as “seen” for reconfigure detection.

Returns

void

notifyChanged()

notifyChanged(): void;

Bump version to signal that tools or prompt have changed.

Returns

void

processToolResult()

processToolResult(
   toolName,
   args,
   result): CapabilityAction;

Route a tool result through capabilities. First capability to claim it wins. If no capability claims it, returns { type: 'continue' } (regular tool).

Parameters

Parameter	Type
`toolName`	`string`
`args`	`unknown`
`result`	`unknown`

Returns

CapabilityAction

use()

use(capability): this;

Add a capability (flow, triage, extraction, etc.).

Parameters

Parameter	Type
`capability`	`Capability`

Returns

this