⚡ TERX

Memory layer for browser agents.

Your agent logs into Salesforce 50 times a day. TERX makes runs 2–50 cost zero tokens.

pip install terx

No Playwright. No Selenium. Raw CDP. Works with Agent VCR.

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The Problem

Every browser agent today is amnesiac.

Run your agent 50 times on the same login flow. It re-discovers the login button all 50 times. Burns LLM tokens re-discovering the login button all 50 times.

Run 1:  LLM finds login button → clicks → succeeds   [$0.008 · 2,100 tokens · 3.2s]
Run 2:  LLM finds login button → clicks → succeeds   [$0.008 · 2,100 tokens · 3.1s]
Run 3:  LLM finds login button → clicks → succeeds   [$0.008 · 2,100 tokens · 3.3s]
...
Run 50: LLM finds login button → clicks → succeeds   [$0.008 · 2,100 tokens · 3.0s]

Total: $0.40 · 105,000 tokens · 2.6 minutes — for the SAME task repeated 50 times

With TERX:

Run 1:  Agent runs normally → TERX records CDP commands    [$0.008 · 2,100 tokens]
Run 2:  TERX replays → done                                [$0.000 ·     0 tokens · 40ms]
Run 3:  TERX replays → done                                [$0.000 ·     0 tokens · 38ms]
...
Run 50: TERX replays → done                                [$0.000 ·     0 tokens · 41ms]

Total: $0.008 · 2,100 tokens — 98% cost reduction

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How It Works

Three components:

1. CDP Bridge — raw asyncio WebSocket to Chrome. No Playwright. No browser testing framework overhead. Single-digit ms execution.

2. DOM Extractor — reads the accessibility tree (not raw HTML). Assigns stable numeric IDs to interactable elements. Computes a fuzzy structural hash that survives minor CSS changes.

3. Muscle Memory Cache — SQLite-backed. On successful task completion, stores the CDP command sequence keyed by (domain, dom_hash). On future runs, replays directly. Writes .vcr files.

4. Self-Healing Replay & SSIM Audits — If the DOM drifts, TERX evaluates the new state via LLM to heal the parameters without dropping back to a full agent evaluation. Every replay takes a snapshot and computes the Structural Similarity Index (SSIM) to warn agents of silent visual UI drift.

---

Quick Start

1. Start Chrome with debugging enabled

google-chrome --remote-debugging-port=9222 --no-first-run
# or for headless:
google-chrome --remote-debugging-port=9222 --headless=new

2. Connect TERX

import asyncio
from terx.cdp.session import BrowserSession
from terx.cache.cache import MuscleMemorycache, session_for

cache = MuscleMemorycache()

async def run_task():
    async with BrowserSession() as session:
        bridge = session.bridge()

        async with session_for(cache, bridge, "login to salesforce") as ctx:
            if ctx.hit:
                # Run 2+: zero LLM tokens, 40ms
                await ctx.replay()
            else:
                # Run 1: your agent runs normally
                # Transparent CDP Proxy auto-records all commands!
                await your_agent.run("login to salesforce")

        print(ctx.ledger)
        # 💾 Cache HIT · 12 commands · 41ms · ~12 LLM calls saved · run #3

asyncio.run(run_task())

3. Or use the MCP server (connect any AI agent)

terx-server

Add to Claude Desktop / Cursor mcp.json:

{
  "mcpServers": {
    "terx": {
      "command": "terx-server"
    }
  }
}

Available MCP tools:

Tool	What it does
browser_get_state	AXTree snapshot — elements with stable IDs
browser_navigate	Navigate to URL
browser_click	Click element by ID
browser_type	Type into input (React/Vue safe)
browser_screenshot	Returns hash ref, NOT base64 blob
browser_scroll	Scroll up/down
browser_new_tab	Open new tab
cache_stats	Hit rate, savings, domains
cache_invalidate	Clear cache for a domain

---

Works with Agent VCR

TERX writes browser sessions in .vcr format — the same format used by Agent VCR.

# Every TERX session writes a .vcr file automatically
# .vcr/browser_salesforce_1234567890.vcr

# Load it in Agent VCR for time-travel debugging:
from agent_vcr import VCRPlayer

player = VCRPlayer.load(".vcr/browser_salesforce_1234567890.vcr")

# See exactly what happened at each step
print(player.goto_frame(3))
# {'cdp_method': 'Input.dispatchMouseEvent', 'cdp_params': {...}, ...}

# See what the cache hit rate was
print(player.get_total_cost())  # 0.0 on replay runs

Agent VCR → undo filesystem damage from coding agents. TERX → zero-token memory for browser agents. Same .vcr format. Same VCRPlayer. Different problems.

---

Why Not Playwright?

Playwright is a testing framework. TERX is an execution layer.

	Playwright	TERX
Purpose	Browser testing	AI agent execution
Protocol	CDP (wrapped)	CDP (raw)
Overhead	~120MB RAM per subprocess	~2MB
Startup	800ms–2s	<50ms
Memory across runs	None	Muscle memory cache
MCP integration	External wrapper needed	Built-in
.vcr output	❌	✅

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The .vcr File Format

Plain JSONL. Human-readable. Git-diffable. Agent VCR compatible.

{"type": "session", "data": {"session_id": "browser_salesforce_...", "agent_type": "browser", "tool": "terx", "task": "login to salesforce", "domain": "salesforce.com", "cache_hit": true}}
{"type": "frame", "data": {"node_name": "page_navigate", "input_state": {"cdp_method": "Page.navigate", "cdp_params": {"url": "https://salesforce.com/login"}}, "output_state": {"cdp_result": {...}}, "metadata": {"latency_ms": 145, "cache_hit": true}}}
{"type": "frame", "data": {"node_name": "input_dispatchmouseevent", "input_state": {"cdp_method": "Input.dispatchMouseEvent", ...}, "metadata": {"latency_ms": 8, "cache_hit": true}}}

---

Security

TERX applies scheme-first URL validation before any navigation:

# Blocked automatically:
browser_navigate("data:text/html,<script>...")    # data: bypass → blocked
browser_navigate("javascript:alert(1)")           # JS injection → blocked
browser_navigate("file:///etc/passwd")            # local file → blocked

# Allowed:
browser_navigate("https://salesforce.com")        # ✅
browser_navigate("http://localhost:3000")          # ✅

Screenshots return hash references, not raw base64 blobs — preventing context poisoning where large images consume your entire LLM context window.

---

Benchmarks

Coming in v0.2: 100-task benchmark vs browser-use baseline.
Preliminary numbers from manual testing:

Task                    | Run 1 (cold)  | Run 2+ (cached) | Savings
─────────────────────────────────────────────────────────────────────
Login (12 CDP commands) | 3.2s · $0.008 | 41ms · $0.000   | 99%
Form fill (8 commands)  | 2.1s · $0.005 | 28ms · $0.000   | 99%
Search + click (6 cmds) | 1.8s · $0.004 | 21ms · $0.000   | 99%

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Roadmap

• Raw CDP bridge (no Playwright)
• Accessibility tree extractor
• Fuzzy DOM structural hasher
• Muscle memory cache (SQLite)
• .vcr output (Agent VCR compatible)
• FastMCP Server with 10 tools
• Framework-adaptive input (React/Vue safe)
• Screenshot hash refs (no context poisoning)
• Self-healing replay (fallback to LLM on DOM drift, auto-update cache)
• Visual Audits via SSIM (Structural Similarity Index)
• Transparent CDP Recording Proxy (zero manual setup)
• MutationObserver cache invalidation
• Local embedding-based element lookup (sentence-transformers)
• browser-use integration wrapper
• Benchmark suite (100 tasks, published results)

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Install

# Core (CDP bridge + cache + MCP server)
pip install terx

# With local embeddings for semantic element lookup
pip install "terx[embeddings]"

# With visual SSIM auditing and LLM-powered self-healing
pip install "terx[vision,healing]"

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Contributing

git clone https://github.com/ixchio/terx
cd terx
pip install -e ".[dev]"
pytest tests/ -v

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License

MIT

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⚡

Run 1 costs tokens. Run 2 costs nothing.

pip install terx

Works with Agent VCR — time-travel debugging for AI agents.

_{Built by ixchio · MIT License}