zap-mdns — mDNS auto-discovery for ZAP services

Replaces the hard-coded [9999..9995] port-probe in browser extensions and the lock-file dance in ~/.hanzo/extension/config.json with proper multicast DNS service discovery (_hanzo._tcp.local., canonical per HIP-0069).

Why

• ZAP currently fixed-ports collide between agents, hosts, and accidentally mature lqd-check test daemons.
• Lock-file registry is single-host and fragile (stale PIDs, race on finally-cleanup).
• mDNS works across the LAN, multi-MCP, multi-host. Bonjour/Avahi gives us service-type browsing for free on every modern OS.

Service definition

type:       _hanzo._tcp.local.
name:       <server_id>._hanzo._tcp.local.
port:       <bound port>
txt:
    server_id   = mcp-py-12345
    agent_label = osage-screenshot-test
    version     = 0.5.0
    capabilities = tabs,navigate,screenshot,evaluate,...
    proto       = zap/1

Layout

python/      Python publisher + browser via `zeroconf`
ts/          TypeScript publisher (Node) + browser shim
ext/         Browser-extension polyfill (native-messaging helper)
README.md    this file

Backwards compat

Existing port-probe path remains in the extension as a fallback. mDNS is attempted FIRST; if zero services found within 2s, fall through to the fixed-port probe. Once mDNS adoption is stable, port-probe is removed.

Install

pip install zap-mdns
# or
uv pip install zap-mdns

Status

Published on PyPI: https://pypi.org/project/zap-mdns/ — wired into ~/work/zap/ for cross-org reuse (hanzo / lux / zoo / liquidity all consume the same package).