# th3ist: Free OpenAI-compatible gateway for t3.chat

`th3ist` is a zero-dependency, standalone Go proxy gateway that exposes an OpenAI-compatible HTTP interface (`/v1/chat/completions` and `/v1/models`) backed by the `t3.chat` API.

## Features

- **Standard OpenAI interface**: Serves `/v1/chat/completions` and `/v1/models` (with `/chat/completions` and `/models` aliases).
- **Dual-engine architecture (Browser Bridge enabled by default)**:
  - **Browser bridge (`-auto-capture`, default: true)**: Routes upstream requests directly through a private, stealth offscreen Chromium session over CDP with automatic virtual X server (`Xvfb`) isolation. This ensures a 100% genuine Chrome TLS handshake (JA3/JA4), completely bypassing Vercel Security Checkpoints and WAF blocks out of the box.
  - **Direct HTTP client (`-direct` / `-no-bridge`)**: Fallback mode for high-throughput environments where valid Vercel clearance cookies and tokens are supplied directly.
- **Real-time per-token streaming**: Streams tokens in real time over CDP via `Runtime.addBinding` and `ReadableStreamDefaultReader`, passing token chunks immediately through stateful thinking and tool call filters without buffering.
- **Automated hardware fingerprint rotation & 429 auto-recovery**: Dynamically discovers FingerprintJS entropy modules (or generates high-entropy synthetic fallbacks) and auto-rotates visitor identities upon encountering `HTTP 429` / rate limits, retrying immediately (up to 4 attempts) without dropping client connections.
- **Private & anti-fingerprinting stealth**:
  - **100% isolated session**: Launches in `--incognito` mode with a temporary ephemeral user profile and `--disable-extensions`, completely segregated from any existing Chromium/Chrome windows, history, extensions, or sessions.
  - **Auto-managed virtual display (`-xvfb`, default: true)**: Spawns an isolated Xvfb display to completely isolate Chromium from tiling window managers (i3, bspwm, sway, dwm).
  - **Zero port collisions**: Binds to a dynamically allocated ephemeral loopback port for CDP commands.
  - **Stealth & anti-detection**:
    - Disables Blink automation features (`--disable-blink-features=AutomationControlled`).
    - Masks `navigator.webdriver` to `undefined` via `Page.addScriptToEvaluateOnNewDocument`.
    - Normalizes `window.chrome`, `navigator.languages`, and `navigator.plugins`.
    - Sets desktop viewport (`--window-size=1920,1080`) and custom User-Agent.
    - Strips telemetry, domain reliability, crash reporting, and sync.
- **Dynamic token ingestion API**: Provides `GET /v1/token` and `POST /v1/token` to inspect or hot-reload single-use hCaptcha tokens and cookies on the fly without restarting the server.
- **Fast fail & clear error propagation**: Non-transient errors (such as `captcha_failed` or `invalid_params`) return immediately (<300ms) without wasting time in exponential backoff retry loops.
- **Reasoning content separation**: Parses `<think>...</think>` tags and upstream reasoning chunks into `reasoning_content` deltas / message fields.
- **Function / tool calling translation**: Injects tool schemas into system instructions, maps multi-turn tool calling history, and parses model tool invocations into standard OpenAI `tool_calls`.
- **Zero external dependencies**: Implemented using pure Go standard library.

## Installation

```bash
go install code.luxferre.top/luxferre/th3ist@latest
```

### Building from source

```bash
make build
```

Binary will be produced at `bin/th3ist`.

## Running

```bash
# Run with default settings (Browser Bridge and isolated Xvfb active)
./bin/th3ist

# Run on a custom port with static defaults
./bin/th3ist -port 9000 -default-model gemini-3.5-flash-lite

# Run in direct HTTP client mode (bypasses browser bridge)
./bin/th3ist -direct
```

### CLI flags

| Flag | Description | Default |
|------|-------------|---------|
| `-auto-capture` | Enable private browser bridge (bypasses Vercel TLS & mints fresh tokens) | `true` |
| `-direct` / `-no-bridge` | Disable browser bridge and run in direct HTTP mode | `false` |
| `-xvfb` / `-Xvfb` | Automatically spawn and manage an isolated virtual X server (`Xvfb`) for complete isolation from tiling window managers | `true` |
| `-no-xvfb` | Disable automatic virtual X server (uses active `$DISPLAY`) | `false` |
| `-display` | Custom X11 DISPLAY to attach Chromium to (e.g. `:99` for an existing Xvfb / Xephyr / Xnest session) | *(auto / `$DISPLAY`)* |
| `-headless` | Force strict headless mode `--headless=new` (defaults to offscreen window when display is present) | `false` |
| `-browser-bin` | Custom path to Chromium/Google Chrome binary | *(auto-detected)* |
| `-port` | Port to listen on | `8080` |
| `-endpoint` | Upstream T3 chat endpoint | `https://t3.chat/api/chat` |
| `-default-model` | Default model identifier | `gemini-3.5-flash-lite` |
| `-cookie` | Cookie string to pass upstream | `""` |
| `-hcaptcha-token` | hCaptcha token to pass upstream | `""` |
| `-deployment-id` | `x-deployment-id` header value | `""` |
| `-client-context` | `x-client-context` header value | `""` |
| `-user-agent` / `-ua` | User-Agent string sent upstream | `Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36` |

### Tiled window managers & virtual display isolation

On tiling window managers (e.g., i3, bspwm, sway, dwm, awesome, hyprland, xmonad), `th3ist` defaults to managing an isolated virtual X server (`-xvfb`) so that no Chromium windows appear on your desktop workspace:

1. **Option A: Auto-managed Xvfb (Default)**:
   Install `xorg-server-xvfb` (or `Xfbdev`):
   - **Void Linux**: `sudo xbps-install -S xorg-server-xvfb`
   - **Debian / Ubuntu**: `sudo apt install xvfb`
   - **Arch Linux**: `sudo pacman -S xorg-server-xvfb`

   `th3ist` will automatically allocate an isolated virtual display (e.g. `:99`), launch `Xvfb`, attach Chromium to it, and cleanly terminate `Xvfb` on exit.

2. **Option B: Manual virtual X server (`Xvfb`, `Xephyr`, or `Xnest`)**:
   ```bash
   # Start virtual framebuffer in background
   Xvfb :99 -screen 0 1280x800x24 -ac &

   # Run th3ist attached to display :99
   ./bin/th3ist -display :99 -port 9000
   ```

3. **Option C: Tiling window manager rules (`--class=th3ist_hidden`)**:
   Chromium is launched with `--class=th3ist_hidden` and `--app=https://t3.chat`. You can add a floating/hidden rule to your window manager config:
   - **i3/sway**: `for_window [class="th3ist_hidden"] floating enable, move scratchpad`
   - **bspwm**: `bspc rule -a th3ist_hidden state=floating hidden=on`

### Token ingestion API

`t3.chat` protects `/api/chat` with single-use hCaptcha tokens. You can inspect or hot-reload tokens live:

- **Inspect current credentials**:
  ```bash
  curl http://localhost:8080/v1/token
  ```
- **Push fresh hCaptcha token**:
  ```bash
  curl -X POST http://localhost:8080/v1/token \
    -H "Content-Type: application/json" \
    -d '{
      "hcaptchaToken": "<new-unconsumed-hcaptcha-token>",
      "cookie": "<optional-new-cookie-string>"
    }'
  ```

### Per-request header overrides

You can also override credentials per request:
- `X-Hcaptcha-Token`: supply a fresh hCaptcha token for a single request.
- `X-Cookie` / `Cookie` / `Authorization: Bearer <cookie-string>`: override upstream cookies.
- `X-Deployment-Id`: override `x-deployment-id`.
- `X-Client-Context`: override `x-client-context`.
- `X-User-Agent`: override upstream User-Agent.

## Usage examples

### 1. List models

```bash
curl http://localhost:8080/v1/models
```

### 2. Chat completion (non-streaming)

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3.5-flash-lite",
    "messages": [
      {"role": "user", "content": "Hello, how are you?"}
    ]
  }'
```

### 3. Chat completion (streaming)

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3.5-flash-lite",
    "messages": [
      {"role": "user", "content": "Tell me a short joke."}
    ],
    "stream": true
  }'
```

### 4. Tool / function calling

```bash
curl http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3.5-flash-lite",
    "messages": [
      {"role": "user", "content": "What is the weather in Tokyo?"}
    ],
    "tools": [
      {
        "type": "function",
        "function": {
          "name": "get_weather",
          "description": "Get current weather for a city",
          "parameters": {
            "type": "object",
            "properties": {
              "location": {"type": "string", "description": "City name"}
            },
            "required": ["location"]
          }
        }
      }
    ]
  }'
```

### 5. Using with official OpenAI Python SDK

```python
from openai import OpenAI

client = OpenAI(
  base_url="http://localhost:8080/v1",
  api_key="not-needed"
)

response = client.chat.completions.create(
  model="gemini-3.5-flash-lite",
  messages=[
    {"role": "user", "content": "Write a quick hello world in Go"}
  ],
  stream=True
)

for chunk in response:
  if chunk.choices[0].delta.content:
    print(chunk.choices[0].delta.content, end="", flush=True)
print()
```

## Credits

Created by Luxferre in 2026, released into the public domain with no warranties.