shadow-web 0.2.1

Local-first Python SDK for AI agents: Shadow DOM flatten, Action Map compression, shadow_grep, self-healing selectors

Shadow Web: Shift-Left Web SDK & API for AI Agents

Shadow Web is an open-source Python SDK for LLM/AI agents. It flattens Shadow DOM and same-origin iframes (read-only), strips HTML bloat, builds a grouped Action Map, and supports local self-healing selectors — no cloud required for the core workflow.

Why Shadow Web?

1. Token savings: Measured 64–97% XML reduction vs raw HTML on benchmark pages (see table below).
2. Action Map + semantic groups: LLMs interact via short IDs and logical blocks (Login Form, Navigation).
3. Local-first: DOM capture + compression run on your machine. Optional local MCP server for Cursor/Claude.

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Benchmarks (measured)

Run locally:

pip install tiktoken           # optional: accurate token counts (cl100k_base)
python benchmarks/run.py       # live Playwright benchmarks (Hacker News, Wikipedia, GitHub)

Counting method: Defaults to chars/4 estimate. With tiktoken installed, counts use the cl100k_base encoder (GPT-4 / DeepSeek).

Page	Raw HTML (tokens)	Grouped XML (tokens)	Actions	Token Reduction
Hacker News	8,637	6,704	227	-22.4% (1.3x)
Wikipedia (Web Scraping)	99,343	16,462	501	-83.4% (6.0x)
GitHub Trending	167,875	37,833	1,290	-77.5% (4.4x)

Notes:

• Grouped XML — the structured action map (xml_map) sent to the LLM agent.
• Actions — number of interactive elements on the page.
• Benchmarks use dom_capture to flatten Shadow DOM and same-origin iframes live before compression.

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Installation

pip install shadow-web
playwright install chromium   # required for ShadowPage / MCP navigate tools

Extras:

pip install "shadow-web[mcp]"          # Cursor / Claude MCP server
pip install "shadow-web[server]"         # optional FastAPI heal API
pip install "shadow-web[browser-use]"  # browser-use integration deps
pip install "shadow-web[all]"            # everything

From source (development):

git clone https://github.com/ulinycoin/shadow-web.git
cd shadow-web
pip install -e ".[dev,server,mcp]"
playwright install chromium

Local MCP (Cursor / Claude Desktop)

{
  "mcpServers": {
    "shadow-web": {
      "command": "shadow-web-mcp"
    }
  }
}

Optional .env:

DEEPSEEK_API_KEY=...                    # for /v1/heal LLM fallback
SHADOW_WEB_HEAL_URL=http://127.0.0.1:8000/v1/heal

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Quick start

Compress HTML (no browser)

from shadow_web.compressor import process_html, generate_grouped_xml_map

raw_html = open("page.html").read()
clean_html, action_map, groups = process_html(raw_html)
xml_map = generate_grouped_xml_map("https://example.com", "Example", groups)
print(xml_map)

Playwright + Shadow DOM flatten

from playwright.sync_api import sync_playwright
from shadow_web.wrapper import ShadowPage

with sync_playwright() as p:
    page = p.chromium.launch(headless=True).new_page()
    page.goto("https://example.com")
    shadow = ShadowPage(page)
    clean_html, xml_map = shadow.refresh()
    print(shadow.capture_stats)  # shadow_hosts, iframes, etc.

shadow_grep — filter before LLM

Instead of sending the full Action Map (500+ elements on GitHub/Wikipedia), query relevant actions:

# After shadow.refresh()
result = shadow.query("intent:login")           # QueryResult
text = shadow.query("intent:login", fmt="terse")  # compact LLM text
subset = shadow.query("type:button; group:Checkout", fmt="xml")

print(text)
# # shadow_grep: intent:login (2/1290)
# @1 button Sign in [Login Form]
# @2 input[email] Email [Login Form]

Query syntax (AND semantics):

Filter	Example
Type	type:button, type:input
Group	group:Login Form
Intent preset	intent:login, intent:checkout, intent:buy
ID list	id:1,3,5
Label regex	label~/checkout/i
Placeholder	placeholder~email
Href	href:/cart
Free text	checkout (matches label/group/type)
Combined	type:button intent:login or type:button; intent:login

MCP: shadow_query(query="intent:login", format="terse") after navigate(url).

WebMCP Bridge (Chrome 145+ preview)

When a page exposes document.modelContext tools, Shadow Web switches to webmcp mode automatically — no DOM snapshot needed:

shadow = ShadowPage(page, prefer_webmcp=True)
clean_html, xml_map = shadow.refresh()

print(shadow.interaction_mode)  # "webmcp" or "action_map"
if shadow.webmcp.available:
    result = shadow.execute_tool("search_products", {"query": "dog toy"})
    # or by Action Map id:
    shadow.execute_tool_by_sid("1", {"query": "dog toy"})

MCP tools:

• webmcp_list_tools() — detect tools on current page
• webmcp_execute_tool(name, arguments='{"query":"x"}')

Fallback: if no WebMCP tools → normal Action Map + Shadow DOM flatten (unchanged).

Page diff — delta snapshots (opt-in)

After the first full snapshot, send only what changed — skeleton (url, title, group names) + appeared/changed/disappeared actions with breadcrumbs:

shadow.refresh()              # full Action Map XML (baseline)
shadow.click("3")
_, delta_xml = shadow.refresh(diff=True)  # delta only on same URL

print(shadow.diff_terse())
# # diff https://example.com
# groups: Login Form, Navigation
# ## appeared
# @4 Checkout > button[Buy now] (#4)

MCP: snapshot(diff=True) after navigate(url) — first call is always full; subsequent calls on the same URL return delta XML + diff_terse.

URL change resets baseline → next snapshot is full again.

Phase 2 — a11y dual mode + verified heal

Dual capture (capture_mode="auto" by default) — DOM flatten + CDP Accessibility tree supplement for closed Shadow DOM:

shadow = ShadowPage(page, capture_mode="auto")  # dom | a11y | dual | auto
shadow.refresh()
print(shadow.capture_stats)  # capture_source, a11y_supplement_nodes, shadow_hosts

• auto — a11y supplement when shadow hosts exist and AX tree exposes uncovered interactives
• dual — always merge uncovered a11y nodes
• a11y bindings click via CDP backendDOMNodeId (closed shadow safe)

Verified heal — selectors validated before cache (local + API):

shadow = ShadowPage(page, verify_heal=True, heal_api_url="http://127.0.0.1:8000/v1/heal")

Server /v1/heal loads context_html in headless Chromium; rejects unverified selectors (422).

Env: SHADOW_WEB_API_KEYS=key1,key2, SHADOW_WEB_RATE_LIMIT=100 (per key / 24h).

Self-healing (local → LLM)

shadow = ShadowPage(page, heal_api_url="http://127.0.0.1:8000/v1/heal")
shadow.click("3")  # binding → local fuzzy heal → LLM API fallback

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Folder structure

src/shadow_web/
  compressor.py      # DOM strip + Action Map + groups
  dom_capture.py     # Shadow DOM / iframe flatten (in-browser, read-only)
  grouping.py        # Semantic groups (forms, nav, modals)
  heal_local.py      # Local selector heal + ~/.shadow-web/heal_cache.json
  query.py           # shadow_grep (type:, intent:, label~, AND filters)
  webmcp.py          # WebMCP bridge (detect + executeTool)
  diff.py            # Page diff (skeleton + delta XML)
  a11y_capture.py    # CDP Accessibility dual capture (closed shadow)
  verified_heal.py   # Playwright selector verification
  wrapper.py         # ShadowPage (Playwright)
  mcp/server.py      # Local MCP tools
server/              # Optional FastAPI (/v1/compress, /v1/heal)
benchmarks/          # Token benchmarks + fixtures
tests/

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API server (optional, local)

uvicorn server.main:app --reload --port 8000
python3 -m unittest discover -s tests -p 'test_*.py' -v

curl -X POST http://localhost:8000/v1/compress \
  -H "Content-Type: application/json" \
  -d '{"html": "<html><body><button>Buy</button></body></html>"}'

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License

MIT License. Free for development and commercial use.