@ljoukov/llm

Unified TypeScript wrapper over:

OpenAI Responses API (openai)
Google Gemini via Vertex AI (@google/genai)
Fireworks chat-completions models (kimi-k2.5, glm-5, minimax-m2.1, gpt-oss-120b)
ChatGPT subscription models via chatgpt-* model ids (reuses Codex auth store, or a token provider)
Agentic orchestration with subagents via runAgentLoop() + built-in delegation control tools

Designed around a single streaming API that yields:

response text deltas
thought (reasoning summary) deltas
usage token counts + estimated USD cost

Install

npm i @ljoukov/llm

Environment variables

This package optionally loads a .env.local file from process.cwd() (Node.js) on first use (dotenv-style KEY=value syntax) and does not override already-set process.env values. It always falls back to plain environment variables.

See Node.js docs on environment variables and dotenv files: https://nodejs.org/api/environment_variables.html#dotenv

OpenAI

OPENAI_API_KEY
OPENAI_RESPONSES_WEBSOCKET_MODE (auto | off | only, default: auto)
OPENAI_BASE_URL (optional; defaults to https://api.openai.com/v1)

Gemini (Vertex AI)

GOOGLE_SERVICE_ACCOUNT_JSON (the contents of a service account JSON key file, not a file path)

Get a service account key JSON

You need a Google service account key JSON for your Firebase / GCP project (this is what you put into GOOGLE_SERVICE_ACCOUNT_JSON).

Firebase Console: your project -> Project settings -> Service accounts -> Generate new private key
Google Cloud Console: IAM & Admin -> Service Accounts -> select/create an account -> Keys -> Add key -> Create new key -> JSON

Either path is enough. Both produce the same kind of service account key .json file.

Official docs: https://docs.cloud.google.com/iam/docs/keys-create-delete

Store the JSON on one line (recommended):

jq -c . < path/to/service-account.json

Set it for local dev:

export GOOGLE_SERVICE_ACCOUNT_JSON="$(jq -c . < path/to/service-account.json)"

If deploying to Cloudflare Workers/Pages:

jq -c . < path/to/service-account.json | wrangler secret put GOOGLE_SERVICE_ACCOUNT_JSON

Fireworks

FIREWORKS_TOKEN (or FIREWORKS_API_KEY)

ChatGPT subscription models

By default, chatgpt-* models reuse the ChatGPT OAuth tokens stored by the Codex CLI:

${CODEX_HOME:-~/.codex}/auth.json

If you deploy to multiple environments (Vercel, GCP, local dev, etc.), use a centralized HTTPS token provider that owns refresh-token rotation and serves short-lived access tokens.

CHATGPT_AUTH_TOKEN_PROVIDER_URL (example: https://chatgpt-auth.<your-domain>)
CHATGPT_AUTH_API_KEY (shared secret; sent as Authorization: Bearer ... and x-chatgpt-auth: ...)
CHATGPT_AUTH_TOKEN_PROVIDER_STORE (kv or d1, defaults to kv)
CHATGPT_RESPONSES_WEBSOCKET_MODE (auto | off | only, default: auto)

This repo includes a Cloudflare Workers token provider implementation in workers/chatgpt-auth/.

If CHATGPT_AUTH_TOKEN_PROVIDER_URL + CHATGPT_AUTH_API_KEY are set, chatgpt-* models will fetch tokens from the token provider and will not read the local Codex auth store.

Responses transport

For OpenAI and chatgpt-* model paths, this library now tries Responses WebSocket transport first and falls back to HTTP/SSE automatically when needed.

auto (default): try WebSocket first, then fall back to SSE
off: use SSE only
only: require WebSocket (no fallback)

When fallback is triggered by an unsupported WebSocket upgrade response (for example 426), the library keeps using SSE for the rest of the process to avoid repeated failing upgrade attempts.

Adaptive per-model concurrency

Provider calls use adaptive, overload-aware concurrency (with retry/backoff where supported). Configure hard caps in code (clamped to 1..64):

import { configureModelConcurrency } from "@ljoukov/llm";

configureModelConcurrency({
  globalCap: 8,
  providerCaps: {
    openai: 16,
    google: 3,
    fireworks: 8,
  },
  modelCaps: {
    "gpt-5.2": 24,
  },
  providerModelCaps: {
    google: {
      "gemini-3.1-pro-preview": 2,
    },
  },
});

Default caps (without configuration):

OpenAI: 12
Google preview models (*preview*): 2
Other Google models: 4
Fireworks: 6

Usage

Use OpenAI-style request fields:

input: string or message array
instructions: optional top-level system instructions
message roles: developer, system, user, assistant

Basic (non-streaming)

import { generateText } from "@ljoukov/llm";

const result = await generateText({
  model: "gpt-5.2",
  input: "Write one sentence about TypeScript.",
});

console.log(result.text);
console.log(result.usage, result.costUsd);

Streaming (response + thoughts + usage)

import { streamText } from "@ljoukov/llm";

const call = streamText({
  model: "gpt-5.2",
  input: "Explain what a hash function is in one paragraph.",
});

for await (const event of call.events) {
  if (event.type === "delta" && event.channel === "thought") {
    process.stderr.write(event.text);
  }
  if (event.type === "delta" && event.channel === "response") {
    process.stdout.write(event.text);
  }
  if (event.type === "usage") {
    console.log("\n\nusage:", event.usage, "costUsd:", event.costUsd);
  }
}

const result = await call.result;
console.log("\nmodelVersion:", result.modelVersion);

Full conversation (multi-turn)

Pass a full message array via input.

import { generateText, type LlmInputMessage } from "@ljoukov/llm";

const input: LlmInputMessage[] = [
  {
    role: "system",
    content: "You are a concise assistant.",
  },
  {
    role: "user",
    content: "Summarize: Rust is a systems programming language.",
  },
  {
    role: "assistant",
    content: "Rust is a fast, memory-safe systems language.",
  },
  {
    role: "user",
    content: "Now rewrite it in 1 sentence.",
  },
];

const result = await generateText({ model: "gpt-5.2", input });
console.log(result.text);

Attachments (files / images)

Use inlineData parts to attach base64-encoded bytes (intermixed with text). inlineData.data is base64 (not a data URL).

Note: inlineData is mapped based on mimeType.

image/* -> image input (input_image)
otherwise -> file input (input_file, e.g. application/pdf)

import fs from "node:fs";
import { generateText, type LlmInputMessage } from "@ljoukov/llm";

const imageB64 = fs.readFileSync("image.png").toString("base64");

const input: LlmInputMessage[] = [
  {
    role: "user",
    content: [
      { type: "text", text: "Describe this image in 1 paragraph." },
      { type: "inlineData", mimeType: "image/png", data: imageB64 },
    ],
  },
];

const result = await generateText({ model: "gpt-5.2", input });
console.log(result.text);

PDF attachment example:

import fs from "node:fs";
import { generateText, type LlmInputMessage } from "@ljoukov/llm";

const pdfB64 = fs.readFileSync("doc.pdf").toString("base64");

const input: LlmInputMessage[] = [
  {
    role: "user",
    content: [
      { type: "text", text: "Summarize this PDF in 5 bullet points." },
      { type: "inlineData", mimeType: "application/pdf", data: pdfB64 },
    ],
  },
];

const result = await generateText({ model: "gpt-5.2", input });
console.log(result.text);

Intermixed text + multiple images (e.g. compare two images):

import fs from "node:fs";
import { generateText, type LlmInputMessage } from "@ljoukov/llm";

const a = fs.readFileSync("a.png").toString("base64");
const b = fs.readFileSync("b.png").toString("base64");

const input: LlmInputMessage[] = [
  {
    role: "user",
    content: [
      { type: "text", text: "Compare the two images. List the important differences." },
      { type: "text", text: "Image A:" },
      { type: "inlineData", mimeType: "image/png", data: a },
      { type: "text", text: "Image B:" },
      { type: "inlineData", mimeType: "image/png", data: b },
    ],
  },
];

const result = await generateText({ model: "gpt-5.2", input });
console.log(result.text);

Gemini

import { generateText } from "@ljoukov/llm";

const result = await generateText({
  model: "gemini-2.5-pro",
  input: "Return exactly: OK",
});

console.log(result.text);

Fireworks

Use Fireworks model ids directly (for example kimi-k2.5, glm-5, minimax-m2.1, gpt-oss-120b):

import { generateText } from "@ljoukov/llm";

const result = await generateText({
  model: "kimi-k2.5",
  input: "Return exactly: OK",
});

console.log(result.text);

ChatGPT subscription models

Use a chatgpt- prefix:

import { generateText } from "@ljoukov/llm";

const result = await generateText({
  model: "chatgpt-gpt-5.1-codex-mini",
  input: "Return exactly: OK",
});

console.log(result.text);

JSON outputs

generateJson() validates the output with Zod and returns the parsed value.

OpenAI API models use structured outputs (json_schema) when possible.
Gemini uses responseJsonSchema.
chatgpt-* models try to use structured outputs too; if the endpoint/account/model rejects json_schema, the call retries with best-effort JSON parsing.

import { generateJson } from "@ljoukov/llm";
import { z } from "zod";

const schema = z.object({
  ok: z.boolean(),
  message: z.string(),
});

const { value } = await generateJson({
  model: "gpt-5.2",
  input: "Return a JSON object with ok=true and message='hello'.",
  schema,
});

console.log(value.ok, value.message);

Streaming JSON outputs

Use streamJson() to stream thought deltas and get best-effort partial JSON snapshots while the model is still generating.

import { streamJson } from "@ljoukov/llm";
import { z } from "zod";

const schema = z.object({
  ok: z.boolean(),
  message: z.string(),
});

const call = streamJson({
  model: "gpt-5.2",
  input: "Return a JSON object with ok=true and message='hello'.",
  schema,
});

for await (const event of call.events) {
  if (event.type === "delta" && event.channel === "thought") {
    process.stdout.write(event.text);
  }
  if (event.type === "json" && event.stage === "partial") {
    console.log("partial:", event.value);
  }
}

const { value } = await call.result;
console.log("final:", value);

If you only want thought deltas (no partial JSON), set streamMode: "final".

const call = streamJson({
  model: "gpt-5.2",
  input: "Return a JSON object with ok=true and message='hello'.",
  schema,
  streamMode: "final",
});

If you want to keep generateJson() but still stream thoughts, pass an onEvent callback.

const { value } = await generateJson({
  model: "gpt-5.2",
  input: "Return a JSON object with ok=true and message='hello'.",
  schema,
  onEvent: (event) => {
    if (event.type === "delta" && event.channel === "thought") {
      process.stdout.write(event.text);
    }
  },
});

Tools

There are three tool-enabled call patterns:

generateText() for provider-native/server-side tools (for example web search).
runToolLoop() for your runtime JS/TS tools (function tools executed in your process).
runAgentLoop() for full agentic loops (a convenience wrapper around runToolLoop() with built-in subagent orchestration and optional filesystem tools).

Architecture note:

Built-in filesystem tools are not a separate execution system.
runAgentLoop() can construct a filesystem toolset, merges your optional custom tools, and calls the same runToolLoop() engine.
This behavior is model-agnostic at API level; profile selection only adapts tool shape for model compatibility.

Provider-Native Tools (`generateText()`)

Use this when the model provider executes the tool remotely (for example search/code-exec style tools).

import { generateText } from "@ljoukov/llm";

const result = await generateText({
  model: "gpt-5.2",
  input: "Find 3 relevant sources about X and summarize them.",
  tools: [{ type: "web-search", mode: "live" }, { type: "code-execution" }],
});

console.log(result.text);

Runtime Tools (`runToolLoop()`)

Use this when the model should call your local runtime functions.

import { runToolLoop, tool } from "@ljoukov/llm";
import { z } from "zod";

const result = await runToolLoop({
  model: "gpt-5.2",
  input: "What is 12 * 9? Use the tool.",
  tools: {
    multiply: tool({
      description: "Multiply two integers.",
      inputSchema: z.object({ a: z.number(), b: z.number() }),
      execute: ({ a, b }) => ({ value: a * b }),
    }),
  },
});

console.log(result.text);

Use customTool() only when you need freeform/non-JSON tool input grammar.

Mid-Run Steering (Queued Input)

You can queue user steering while a tool loop is already running. Steering is applied on the next model step (it does not interrupt the current generation/tool execution).

import { streamToolLoop, tool } from "@ljoukov/llm";
import { z } from "zod";

const call = streamToolLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Start implementing the feature.",
  tools: {
    echo: tool({
      inputSchema: z.object({ text: z.string() }),
      execute: ({ text }) => ({ text }),
    }),
  },
});

// Append steering while run is active.
call.append("Focus on tests first, then refactor.");

const result = await call.result;
console.log(result.text);

If you already manage your own run lifecycle, you can create and pass a steering channel directly:

import { createToolLoopSteeringChannel, runAgentLoop } from "@ljoukov/llm";

const steering = createToolLoopSteeringChannel();
const run = runAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Implement the task.",
  filesystemTool: true,
  steering,
});

steering.append("Do not interrupt; apply this guidance on the next turn.");
const result = await run;

Agentic Loop (`runAgentLoop()`)

runAgentLoop() is the high-level agentic API. It supports:

optional filesystem workspace tools,
built-in subagent orchestration (delegate work across spawned agents),
your own custom runtime tools.

For interactive runs where you want to stream events and inject steering mid-run, use streamAgentLoop():

import { streamAgentLoop } from "@ljoukov/llm";

const call = streamAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Start implementation.",
  filesystemTool: true,
});

call.append("Prioritize a minimal diff and update tests.");
const result = await call.result;
console.log(result.text);

1) Filesystem agent loop

For read/search/write tasks in a workspace, enable filesystemTool. The library auto-selects a tool profile by model when profile: "auto":

Codex-like models: Codex-compatible filesystem tool shape.
Gemini models: Gemini-compatible filesystem tool shape.
Other models: model-agnostic profile (currently Gemini-style).

Confinement/policy is set through filesystemTool.options:

cwd: workspace root for path resolution.
fs: backend (createNodeAgentFilesystem() or createInMemoryAgentFilesystem()).
checkAccess: hook for allow/deny policy + audit.
allowOutsideCwd: opt-out confinement (default is false).

Detailed reference: docs/agent-filesystem-tools.md.

Filesystem-only example:

import { createInMemoryAgentFilesystem, runAgentLoop } from "@ljoukov/llm";

const fs = createInMemoryAgentFilesystem({
  "/repo/src/a.ts": "export const value = 1;\n",
});

const result = await runAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Change value from 1 to 2 using filesystem tools.",
  filesystemTool: {
    profile: "auto",
    options: {
      cwd: "/repo",
      fs,
    },
  },
});

console.log(result.text);

2) Add subagent orchestration

Enable subagentTool to allow delegation via Codex-style control tools:

spawn_agent, send_input, resume_agent, wait, close_agent
optional limits: maxAgents, maxDepth, wait timeouts
spawn_agent.agent_type supports built-ins aligned with codex-rs-style roles: default, researcher, worker, reviewer

import { runAgentLoop } from "@ljoukov/llm";

const result = await runAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Plan the work, delegate in parallel where useful, and return a final merged result.",
  subagentTool: {
    enabled: true,
    maxAgents: 4,
    maxDepth: 2,
  },
});

console.log(result.text);

3) Combine filesystem + subagents

import { createInMemoryAgentFilesystem, runAgentLoop } from "@ljoukov/llm";

const fs = createInMemoryAgentFilesystem({
  "/repo/src/a.ts": "export const value = 1;\n",
});

const result = await runAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Change value from 1 to 2 using filesystem tools.",
  filesystemTool: {
    profile: "auto",
    options: {
      cwd: "/repo",
      fs,
    },
  },
  subagentTool: {
    enabled: true,
    maxAgents: 4,
    maxDepth: 2,
  },
});

console.log(result.text);

Agent Telemetry (Pluggable Backends)

runAgentLoop() supports optional telemetry hooks that keep default behavior unchanged. You can attach any backend by implementing a sink with emit(event) and optional flush().

import { runAgentLoop } from "@ljoukov/llm";

const result = await runAgentLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Summarize the report and update output JSON files.",
  filesystemTool: true,
  telemetry: {
    includeLlmStreamEvents: false, // enable only if you need token/delta event fan-out
    sink: {
      emit: (event) => {
        // Forward to your backend (Cloud Logging, OpenTelemetry, Datadog, etc.)
        // event.type: "agent.run.started" | "agent.run.stream" | "agent.run.completed"
        // event carries runId, parentRunId, depth, model, timestamp + payload
      },
      flush: async () => {
        // Optional: flush buffered telemetry on run completion.
      },
    },
  },
});

Telemetry emits parent/child run correlation (runId + parentRunId) for subagents. See docs/agent-telemetry.md for event schema, design rationale, and backend adapter guidance.

If you need exact control over tool definitions, build the filesystem toolset yourself and call runToolLoop() directly.

import {
  createFilesystemToolSetForModel,
  createInMemoryAgentFilesystem,
  runToolLoop,
} from "@ljoukov/llm";

const fs = createInMemoryAgentFilesystem({ "/repo/a.ts": "export const n = 1;\n" });
const tools = createFilesystemToolSetForModel("chatgpt-gpt-5.3-codex", {
  cwd: "/repo",
  fs,
});

const result = await runToolLoop({
  model: "chatgpt-gpt-5.3-codex",
  input: "Update n to 2.",
  tools,
});

Agent benchmark (filesystem extraction)

For filesystem extraction/summarization evaluation across Codex, Fireworks, and Gemini models:

npm run bench:agent

Standard full refresh (all tasks, auto-write LATEST_RESULTS.md, refresh traces/latest, prune old traces):

npm run bench:agent:latest

Estimate-only:

npm run bench:agent:estimate

See benchmarks/agent/README.md for options and output format.

Examples

Interactive CLI chat with mid-run steering, thought streaming, filesystem tools rooted at the current directory, subagents enabled, and Esc interrupt support:

npm run example:cli-chat

License

MIT

Name		Name	Last commit message	Last commit date
Latest commit History 77 Commits
.github/workflows		.github/workflows
benchmarks		benchmarks
docs		docs
examples		examples
src		src
test		test
workers/chatgpt-auth		workers/chatgpt-auth
.gitignore		.gitignore
AGENTS.md		AGENTS.md
LICENSE		LICENSE
README.md		README.md
biome.json		biome.json
package-lock.json		package-lock.json
package.json		package.json
tsconfig.json		tsconfig.json
tsup.config.ts		tsup.config.ts
vitest.integration.config.ts		vitest.integration.config.ts
vitest.unit.config.ts		vitest.unit.config.ts

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@ljoukov/llm

Install

Environment variables

OpenAI

Gemini (Vertex AI)

Get a service account key JSON

Fireworks

ChatGPT subscription models

Responses transport

Adaptive per-model concurrency

Usage

Basic (non-streaming)

Streaming (response + thoughts + usage)

Full conversation (multi-turn)

Attachments (files / images)

Gemini

Fireworks

ChatGPT subscription models

JSON outputs

Streaming JSON outputs

Tools

Provider-Native Tools (generateText())

Runtime Tools (runToolLoop())

Mid-Run Steering (Queued Input)

Agentic Loop (runAgentLoop())

1) Filesystem agent loop

2) Add subagent orchestration

3) Combine filesystem + subagents

Agent Telemetry (Pluggable Backends)

Agent benchmark (filesystem extraction)

Examples

License

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Provider-Native Tools (`generateText()`)

Runtime Tools (`runToolLoop()`)

Agentic Loop (`runAgentLoop()`)

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