Synheart Behavior

Overview

The Synheart Behavior Chrome Extension extends behavioral input to the desktop browser. It captures how you interact with Chrome — rhythm, attention, movement patterns — not what you read or type, and streams anonymized session events to your local Synheart Sensor Agent. It produces the same event shape as the mobile SDKs (Flutter, Kotlin, Swift), so the browser becomes another input source for the same downstream pipeline. As with the mobile SDKs, the extension is an input layer; higher-level metrics (focus, distraction, HSI fields) are derived downstream — see the Behavior overview. Distribution: Source-available. The repository is open for reading, auditing, and filing issues. Pull requests are not accepted — see the repo’s CONTRIBUTING.md. Security reports follow SECURITY.md.

Privacy posture

The extension records interaction timing and patterns only. It does not record URLs, page titles, passwords, or typed content. Tabs use anonymous labels (tab-1, tab-2). Sites are classified into generic categories only.

Captured	Never captured
Mouse movement patterns (not precise positions tied to page content)	URLs or page titles
Keystroke timing (categories: letter / digit / symbol — never which key)	Typed content, passwords, or search queries
Tab-switch timing with anonymized tab IDs	Clipboard, form values, or link destinations
Scroll patterns and reversals	Media URLs
Generic site categories	—

Site categories

Category	Examples
`search-engine`	Google, Bing, DuckDuckGo
`video-platform`	YouTube, Vimeo, Twitch
`code-repository`	GitHub, GitLab, Bitbucket
`developer-qa`	Stack Overflow, Stack Exchange
`social-media`	Facebook, X, LinkedIn
`forum`	Reddit
`e-commerce`	Amazon, eBay
`email`	Gmail, Outlook
`documentation`	Google Docs, Notion
`local-development`	localhost, 127.0.0.1
`website`	Default for other sites

Installation

From source

git clone https://github.com/synheart-ai/synheart-behavior-chrome.git
cd synheart-behavior-chrome
npm install
npm run build

Load the extension in Chrome:

Open chrome://extensions
Enable Developer mode
Click Load unpacked and select the dist folder

For iterative development, run npm run build -- --watch and use Reload on the extension card after each change.

Requirements

Chrome (Manifest V3)
A running Synheart Sensor Agent reachable on a configured host/port (typically 127.0.0.1)

Quick start

Start the sensor agent.
Open the extension popup, go to Sensor, set the port and auth token, choose Save, then Test Connection.
Toggle the main switch to ON to begin capture. Use Stats and HSI in the popup to verify flow.

There is no account in this repo — only your local configuration.

Tab	Purpose
Stats	Buffered events, session id, sensor-agent status.
Sensor	Port, auth token, test + save.
HSI	Latest human-state readouts when your agent returns them.

Behavioral metrics captured

Focus and attention

Metric	Description
Tab switch	Moves between tabs (anonymized IDs).
Tab hijacking	Rapid tab switches within a short window (e.g. 5 seconds).
Window focus / blur	Browser focus at the OS level.
Visibility change	Tab hidden / visible transitions.
Cursor parking	Where the cursor settles (e.g. by quadrant).

Micro-motor patterns

Metric	Description
Cursor path tortuosity	Movement efficiency (1.0 ≈ straight; higher ≈ more hesitant).
Click dwell	How long the mouse button is held.
Scroll events	Velocity, direction, ratchet vs linear.
Scroll reversals	Direction flips (re-reading–style signal).

Keystroke dynamics (timing only)

Metric	Description
Key hold time	By category (letter, digit, symbol) — never which key.
Flight time	Gap between releasing one key and pressing the next.
Backspace burst	Rapid backspace bursts (e.g. 3+ in 500ms).
Modifier combos	Ctrl / Alt / Shift / Meta usage patterns.

Metric	Description
Navigation events	Transition type (typed, link, reload, generated).
Anchor scanning	Link hover duration, internal vs external.
Form submit	GET vs POST (method only).

Session payload

The extension batches browser events into session payloads and POSTs them to the sensor agent.

{
  "session": {
    "session_id": "SESS-1768471200000",
    "device_id": "chrome-abc12345",
    "timezone": "America/New_York",
    "start_time": "2026-01-15T10:00:00.000Z",
    "end_time": "2026-01-15T10:05:00.000Z",
    "events": [
      {
        "timestamp": "2026-01-15T10:00:05.000Z",
        "event_type": "app_switch",
        "app_switch": {
          "from_app_id": "tab-1",
          "to_app_id": "tab-2",
          "site_category": "code-repository"
        }
      },
      {
        "timestamp": "2026-01-15T10:00:10.000Z",
        "event_type": "scroll",
        "scroll": {
          "velocity": 150,
          "direction": "down",
          "direction_reversal": false
        }
      },
      {
        "timestamp": "2026-01-15T10:00:15.000Z",
        "event_type": "typing",
        "typing": {
          "key_category": "letter",
          "hold_ms": 85,
          "flight_ms": 120
        }
      }
    ],
    "meta": {
      "source": "synheart-behavior-chrome",
      "version": "0.0.1",
      "event_count": 45
    }
  }
}

Event type mapping

Browser concept	`event_type`
Tab switch	`app_switch`
Scroll	`scroll`
Click dwell	`tap`
Cursor path	`swipe`
Keystroke timing	`typing`
Focus / blur	`focus`
Idle	`idle`
Navigation	`navigation`

Sensor agent endpoint

POST http://127.0.0.1:{port}/collect
Authorization: Bearer {token}
Content-Type: application/json

Body: { "session": { ... } } as produced by the extension. Response shape varies with agent version.

Repository layout

Repository root: LICENSE, README.md
synheart-behavior/ (extension package)
- manifest.json — Chrome MV3 manifest
- background.js — Service worker (batch + send)
- content.js — Behavioral capture
- popup.html
- src/popup.js, src/popup.css
- icons/

Testing

Validate manifest and JavaScript syntax:

node -e "JSON.parse(require('fs').readFileSync('synheart-behavior/manifest.json','utf8'))"
node --check synheart-behavior/background.js
node --check synheart-behavior/content.js
node --check synheart-behavior/src/popup.js

For manual verification, load unpacked from dist, open the Sensor tab, enable recording, and confirm events in your agent logs.

Resources

Repository: synheart-behavior-chrome
Sensor agent: Synheart Sensor Agent
Behavior concepts: Synheart Behavior overview, Metric definitions, Threat model

License

Licensed under the Apache License, Version 2.0.

Get Started

Setup

CLI

Platform

HSI

Synheart Wear

Synheart Auth

Synheart Core

Syni

Syni Spec

Synheart Session

RAMEN 🍜

Lab Mode

Privacy

Guides

Synheart Behavior - Chrome Extension

Overview

Privacy posture

Site categories

Installation

From source

Requirements

Quick start

Behavioral metrics captured

Focus and attention

Micro-motor patterns

Keystroke dynamics (timing only)

Navigation patterns

Session payload

Event type mapping

Sensor agent endpoint

Repository layout

Testing

Resources

License

​Overview

​Privacy posture

​Site categories

​Installation

​From source

​Requirements

​Quick start

​Popup tabs

​Behavioral metrics captured

​Focus and attention

​Micro-motor patterns

​Keystroke dynamics (timing only)

​Navigation patterns

​Session payload

​Event type mapping

​Sensor agent endpoint

​Repository layout

​Testing

​Resources

​License

Overview

Privacy posture

Site categories

Installation

From source

Requirements

Quick start

Popup tabs

Behavioral metrics captured

Focus and attention

Micro-motor patterns

Keystroke dynamics (timing only)

Navigation patterns

Session payload

Event type mapping

Sensor agent endpoint

Repository layout

Testing

Resources

License