huggr-typescript

name	huggr-typescript
description	Define and run huglets in TypeScript or JavaScript through the huggr-agents WASM runtime, with Node or browser storage, callable tools, streaming events, feedback, and cross-language trace verification. Use when building a Node agent, a browser-hosted agent, or a custom TypeScript host around huggr-core.

Build Huggr agents with TypeScript

Use the root package for platform-neutral types and in-memory stores. Use huggr-agents/node for filesystem-backed Node agents and huggr-agents/browser for IndexedDB-backed browser agents. Read Define an agent in TypeScript for the complete surface.

Build the package

cd bindings/typescript
npm install
npm run build:wasm
npm run build

build:wasm requires Rust, the wasm32-unknown-unknown target, and wasm-bindgen. Node usage requires Node 18 or newer.

Define a Node agent

import { createAgent } from "huggr-agents/node";

const agent = createAgent({
  name: "policy-helper",
  system: "Use lookup_policy and return a JSON object.",
  models: { default: "balanced" },
  tools: [{
    name: "lookup_policy",
    description: "Search policy text by keyword.",
    schema: {
      type: "object",
      properties: { query: { type: "string" } },
      required: ["query"],
    },
    invoke: async (args) => ({ matches: await searchPolicyText((args as { query: string }).query) }),
  }],
});

const answer = await agent.ask("Can I expense a train ticket?");
await agent.verify(answer.trace_id);

Tool functions are trusted host code. Registration limits what the model can invoke but does not sandbox the implementation body. An exception from invoke becomes a semantic tool error returned to the model.

Stream and resume

for await (const event of agent.run("What receipt is needed?", { traceId: answer.trace_id })) {
  if (event.type === "text_delta") process.stdout.write(event.text);
  if (event.type === "answer_ready") console.log(event.answer);
}

Model text deltas are yielded as the provider stream delivers them; other events retain their order.

Pass extra for trace metadata and an AbortSignal as signal for cancellation. A resumed ask restores the parent trace's recorded policy, writes a new trace with depends_on, and never mutates the parent.

Choose Node or browser storage

Node resolves HUGGR_AGENT_HOME, then HUGGR_HOME/<name>, then ~/.huggr/<name>, and writes portable trace/feedback files. Browser agents use createAgent from huggr-agents/browser, load WASM over fetch, and persist through IndexedDB.

Browser trace writes use atomic IndexedDB add claims. Concurrent content-id collisions allocate -N suffixes instead of overwriting or surfacing ConstraintError.

The runtime resolves the fixed fast, balanced, powerful, and max tiers from its built-in catalog. The built-in catalog leaves max unset, so it falls back to powerful. Pass modelCatalog in the optional runtime object to override providers, model ids, and prices. Hugging Face Inference Providers lists provider and model combinations for the built-in hf provider. For another OpenAI-compatible service, give it a separate provider alias with its own base_url API URL and credential configuration. Browsers have no environment variables, so put api_key on the runtime provider from a user-controlled settings store and never bake a production secret into a published bundle. Supply custom TraceStore and FeedbackStore implementations through the runtime when the built-in fs, IndexedDB, or memory stores do not fit.

Provider-reported usage cost is authoritative for answer metadata and max_cost_micro_usd; configured token prices are the fallback when the provider reports no cost.

The OpenAI-compatible adapter retries transport failures and 429/5xx responses before streaming begins. Mid-stream failures are final.

Context policy

Pass context using manifest-shaped keys:

context: {
  compaction: "truncate",
  budget_tokens: 64000,
  trigger_tokens: 56000,
  keep_recent_tokens: 8000,
  max_block_tokens: 2000,
  keep_last_per_tool: { page_snapshot: 1 },
}

Compaction runs inside the WASM brain. Do not add unrecorded summarizer or request-pruning calls in the host adapter.

Validate and troubleshoot

cd bindings/typescript
npm test

• Missing pkg/: run npm run build:wasm before npm test or browser packaging.
• Missing target: run rustup target add wasm32-unknown-unknown.
• wasm-bindgen schema mismatch: install the version required by the repository build script.
• Provider auth in Node: set the variable named by the resolved provider's api_key_env (HF_TOKEN for the built-in catalog); in browsers, inject api_key through a runtime modelCatalog from a user-controlled settings store.
• Trace drift: call agent.verify(id). Use $huggr-debug-traces or the Rust CLI when a matching manifest-defined agent resolves to the same Node trace store.