WebSocket Protocol

Jenny exposes a WebSocket server channel used by the Android WebView UI and any compatible client — this page documents the wire protocol for integrators writing their own client.

On the Android device, this is not optional

Everything below describes the general-purpose channel as configured through config.json’s websocket object. On the shipped Android app, the runtime overrides several of these fields at startup regardless of what config.json says:

The gateway always binds host 127.0.0.1 and a single port, 18790, shared by both the WebSocket upgrade and the HTTP /api/ and /webui/ routes — one origin for the WebView to talk to. This overrides gateway.port / websocket.port from config every time the app starts.
websocket.enabled ends up true in practice: the auto-generated config.json created on first run writes "websocket": {"enabled": true, ...} explicitly, and the startup path additionally fills in enabled: true if the key is ever missing. The schema-level default of enabled: false (documented below) only applies when the gateway is run detached from the Android runtime — e.g. invoking run_gateway(...) yourself for local testing, where you own config.json and nothing forces it on.

So: the enabled: false default, the 8765 default port, and a custom host/path are all real and correct for off-device use of this channel (running the gateway standalone on a workstation), but not for the Android APK, which always ends up on ws://127.0.0.1:18790/.

Features

Bidirectional real-time communication over WebSocket
Streaming support — receive agent responses token by token
Secret-based authentication (single shared secret for WebSocket and HTTP APIs)
Single shared chat — every connection joins the unified conversation (chat_id always "default")
TLS/SSL support (WSS) with enforced TLSv1.2 minimum
Client allow-list via allowFrom
Auto-cleanup of dead connections

Quick Start (off-device / standalone gateway)

1. Configure

Add to config.json under the top-level websocket object:

{
  "websocket": {
  "enabled": true,
  "host": "127.0.0.1",
  "port": 8765,
  "path": "/",
  "websocketRequiresToken": false,
  "allowFrom": ["*"],
  "streaming": true
  }
}

The default host: 127.0.0.1 is intended for loopback use. External connections can be allowed by setting host to "0.0.0.0" and configuring allowFrom carefully.

2. Start the gateway

Use the same entry point the Android runtime uses:

from jenny.android_entry import run_gateway
run_gateway("/path/to/data_dir")

Note the argument is a data directory, not the workspace itself — the gateway creates and uses <data_dir>/workspace. Passing a path that already ends in workspace produces a nested workspace/workspace.

You should see:

WebSocket server listening on ws://127.0.0.1:8765/

(On the Android device this line always reads ws://127.0.0.1:18790/ instead, per the note above.)

3. Connect a client

Connect to ws://{host}:{port}{path}?client_id={id}&token={secret} from the Android WebView or another WebSocket client. The wire protocol is described below.

Connection URL

ws://{host}:{port}{path}?client_id={id}&token={secret}

Parameter	Required	Description
`client_id`	No	Identifier for `allowFrom` authorization. Auto-generated as `anon-xxxxxxxxxxxx` if omitted. Truncated to 128 chars.
`token`	Conditional	The `token_issue_secret` value. Required when `websocketRequiresToken` is `true` (the default).

Wire Protocol

All frames are JSON text. Each message has an event field.

Server → Client

ready — sent immediately after connection is established:

{
  "event": "ready",
  "chat_id": "default",
  "client_id": "alice"
}

message — full agent response:

{
  "event": "message",
  "chat_id": "default",
  "text": "Hello! How can I help?",
  "media": ["/tmp/image.png"],
  "reply_to": "msg-id"
}

media and reply_to are only present when applicable.

delta — streaming text chunk (only when streaming: true):

{
  "event": "delta",
  "chat_id": "default",
  "text": "Hello",
  "stream_id": "s1"
}

stream_end — signals the end of a streaming segment:

{
  "event": "stream_end",
  "chat_id": "default",
  "stream_id": "s1"
}

reasoning_delta — incremental model reasoning / thinking chunk for the active assistant turn. Mirrors delta but targets the reasoning bubble above the answer rather than the answer body:

{
  "event": "reasoning_delta",
  "chat_id": "default",
  "text": "Let me decompose ",
  "stream_id": "r1"
}

reasoning_end — close marker for the active reasoning stream. WebUI uses this to lock the in-place bubble and switch from the shimmer header to a static collapsed state:

{
  "event": "reasoning_end",
  "chat_id": "default",
  "stream_id": "r1"
}

Reasoning frames only flow when the channel’s showReasoning is true (default) and the model returns reasoning content (DeepSeek-R1 / Kimi / MiMo / OpenAI reasoning models, Anthropic extended thinking, or inline <think> / <thought> tags). Models without reasoning produce zero reasoning_delta frames.

runtime_model_updated — broadcast when the gateway runtime model changes, for example after /model <preset>:

{
  "event": "runtime_model_updated",
  "model_name": "openai/gpt-4.1-mini",
  "model_preset": "fast"
}

model_preset is omitted when no named preset is active. WebUI clients use this event to keep the displayed model badge in sync across slash commands, config reloads, and settings changes.

attached — confirmation for attach inbound envelopes (see The shared chat):

{"event": "attached", "chat_id": "default"}

error — soft error for malformed inbound envelopes. The connection stays open:

{"event": "error", "detail": "invalid chat_id"}

Client → Server

Legacy (default chat): send a plain string, or a JSON object with a recognized text field:

"Hello Jenny!"

{"content": "Hello Jenny!"}

Recognized fields: content, text, message (checked in that order). Invalid JSON is treated as plain text. These frames route to the shared chat (default, announced in ready).

Typed envelopes: any JSON object with a string type field is a typed envelope:

`type`	Fields	Effect
`attach`	—	(Re)subscribe to the shared chat, e.g. after a reconnect. Replies with `attached`. Any `chat_id` field is ignored.
`message`	`content`	Send `content` on the shared chat. Any `chat_id` field is ignored.

See The shared chat for the full flow.

Configuration Reference

All fields go under the top-level websocket object in config.json. These are the schema-level defaults — remember that on the Android device enabled, host, and port are overridden at startup as described above, regardless of what is written here.

Connection

Field	Type	Default	Description
`enabled`	bool	`false`	Enable the WebSocket server. Effectively always `true` on the Android device (see above).
`host`	string	`"127.0.0.1"`	Bind address. Use `"0.0.0.0"` to accept external connections. Forced to `127.0.0.1` on Android.
`port`	int	`8765`	Listen port. Forced to `18790` (shared with HTTP) on Android.
`path`	string	`"/"`	WebSocket upgrade path. Trailing slashes are normalized (root `/` is preserved).
`maxMessageBytes`	int	`37748736`	Maximum inbound message size in bytes (1 KB – 40 MB). Default (36 MB) is sized to accept up to 4 base64-encoded image attachments at 8 MB each; lower it if the channel only carries text.

Authentication

Field	Type	Default	Description
`websocketRequiresToken`	bool	`true`	When `true`, clients must present `token_issue_secret` as `?token=...` during the WebSocket handshake. Set to `false` to allow unauthenticated connections (only safe for local/trusted networks).
`tokenIssueSecret`	string	`""`	Shared secret for WebSocket and HTTP API authentication. If empty, the bootstrap endpoint falls back to localhost-only on `127.0.0.1`/`::1`, and HTTP API routes reject all requests. Must be set for non-loopback deployments. On Android this is auto-generated per install (see Security Notes) and should never be edited out.

Access Control

Field	Type	Default	Description
`allowFrom`	list of string	`["*"]`	Allowed `client_id` values. `"*"` allows all; `[]` denies all.

Streaming

Field	Type	Default	Description
`streaming`	bool	`true`	Enable streaming mode. The agent sends `delta` + `stream_end` frames instead of a single `message`.

Keep-alive

Field	Type	Default	Description
`pingIntervalS`	float	`20.0`	WebSocket ping interval in seconds (5 – 300).
`pingTimeoutS`	float	`20.0`	Time to wait for a pong before closing the connection (5 – 300).

TLS/SSL

Field	Type	Default	Description
`sslCertfile`	string	`""`	Path to the TLS certificate file (PEM). Both `sslCertfile` and `sslKeyfile` must be set to enable WSS.
`sslKeyfile`	string	`""`	Path to the TLS private key file (PEM). Minimum TLS version is enforced as TLSv1.2.

Authentication Flow

For production deployments where websocketRequiresToken: true (the default, and the effective state on Android), clients authenticate with the shared tokenIssueSecret directly.

How it works

The legitimate client (e.g. the Android WebView) reads token_issue_secret from the private workspace config.json.
The client calls GET /webui/bootstrap with Authorization: Bearer <secret> or X-Jenny-Auth: <secret> to receive connection metadata (WebSocket URL, model name, etc.).
The client opens the WebSocket with ?token=<secret>&client_id=....
The same secret is used for all subsequent HTTP API requests via Authorization: Bearer <secret>.

On the Android app specifically, Kotlin reads the secret from config.json and hands it to the WebView as a URL fragment (#bs=...), never as a query parameter, so it never ends up in logs or server-side request records; the WebView’s JavaScript exchanges it at /webui/bootstrap for the actual WebSocket URL.

Example setup

{
  "websocket": {
  "enabled": true,
  "port": 8765,
  "path": "/ws",
  "tokenIssueSecret": "your-secret-here",
  "websocketRequiresToken": true,
  "allowFrom": ["*"],
  "streaming": true
  }
}

Client flow:

Read websocket.token_issue_secret from the app’s private workspace.
Call GET /webui/bootstrap with X-Jenny-Auth: your-secret-here.
Connect to the WebSocket with ?client_id=alice&token=your-secret-here.
Call HTTP APIs with Authorization: Bearer your-secret-here.

The shared chat

Every connection participates in the single unified conversation: the server forces chat_id to "default" on all envelopes and fans outbound events out to every connected client (e.g. multiple Android activities or desktop browser tabs during local testing). There is no per-connection or per-user chat — any client presenting a valid credential sees and shares the same conversation.

Typical flow

client                                server
  | --- connect -------------------->  |
  | <-- {"event":"ready",              |
  |      "chat_id":"default"}          |
  |                                     |
  | --- {"type":"message",              |
  |      "content":"hi"} ------------>  |
  | <-- {"event":"delta", ...}          |
  | <-- {"event":"stream_end", ...}     |
  |                                     |
  | --- {"type":"attach"} ----------->  |  # after page reload
  | <-- {"event":"attached",            |
  |      "chat_id":"default"}           |

Rules

Every outbound event carries chat_id, always "default".
Client-supplied chat_id fields are ignored: everything routes to the shared chat.
Errors (invalid envelope, unknown type, missing content) are soft: the server replies with {"event":"error","detail":"..."} and keeps the connection open.

Backward compatibility

Legacy clients that only send plain text or {"content": ...} keep working unchanged: those frames route to the shared chat. No config flag is needed.

Security boundary

Anyone holding a valid WebSocket auth credential joins the shared conversation and sees its output. This is safe for Jenny’s local, single-user model; auth on the handshake is the single line of defense.

Security Notes

Timing-safe comparison: Secret validation uses hmac.compare_digest to prevent timing attacks.
Defense in depth: allowFrom is checked at both the HTTP handshake level and the message level.
Shared chat: see The shared chat. Auth on the WebSocket handshake is the single line of defense; callers who pass it join the unified conversation.
TLS enforcement: When SSL is enabled, TLSv1.2 is the minimum allowed version.
Default-secure: websocketRequiresToken defaults to true. Explicitly set it to false only on trusted networks.
Per-install secret on Android: the app generates token_issue_secret once at first boot (secrets.token_urlsafe(32)) and writes it into config.json with permissions restricted to 0600. If you strip it out by hand, it is silently regenerated on the next start (unless a token field is already set, which is left untouched). It is never transmitted anywhere except between the WebView and the local gateway.

Media Files

Outbound message events may include a media field containing local filesystem paths. Remote clients cannot access these files directly — they need either:

A shared filesystem mount, or
An HTTP file server serving the Jenny media directory

Common Patterns

These are off-device / standalone-gateway patterns — they do not apply to the Android app, which always forces host: 127.0.0.1, port: 18790, enabled: true.

Trusted local network (no auth)

{
  "websocket": {
  "enabled": true,
  "host": "0.0.0.0",
  "port": 8765,
  "websocketRequiresToken": false,
  "allowFrom": ["*"],
  "streaming": true
  }
}

Shared secret (simple auth)

{
  "websocket": {
  "enabled": true,
  "tokenIssueSecret": "my-shared-secret",
  "allowFrom": ["alice", "bob"]
  }
}

Clients connect with ?token=my-shared-secret&client_id=alice and send HTTP APIs with Authorization: Bearer my-shared-secret.

Public endpoint with authentication

{
  "websocket": {
  "enabled": true,
  "host": "0.0.0.0",
  "port": 8765,
  "path": "/ws",
  "tokenIssueSecret": "production-secret",
  "websocketRequiresToken": true,
  "sslCertfile": "/etc/ssl/certs/server.pem",
  "sslKeyfile": "/etc/ssl/private/server-key.pem",
  "allowFrom": ["*"]
  }
}

Custom path

{
  "websocket": {
  "enabled": true,
  "path": "/chat/ws",
  "allowFrom": ["*"]
  }
}

Clients connect to ws://127.0.0.1:8765/chat/ws?client_id=.... Trailing slashes are normalized, so /chat/ws/ works the same.