feat: monitor en vivo (--watch) y publish --address; interop validada

Añade las dos funciones que Avahi/Bonjour tenían y faltaban:

- `mdns browse --watch`: monitor DNS-SD en vivo (eventos +/=/-), equivalente
  a `avahi-browse -a`. Sin --type descubre tipos dinámicamente via el
  meta-servicio _services._dns-sd._udp.local. y adjunta un browser por tipo.
  Nuevo modulo lib/mdns_tools/watch.py.
- `mdns publish --address <nombre> <ip>`: publica un A record puro
  hostname->IP, equivalente a `avahi-publish -a`.

Robustez del publisher:
- Maneja NonUniqueNameException (probing RFC 6762): si el nombre ya esta
  tomado, deja que zeroconf renombre en vez de crashear.
- `mdns publish` sin --config auto-carga ~/.config/mdns/services.json.

Interoperabilidad validada en LAN real (documentada en README):
- Termux -> Avahi: con `mdns publish` activo, un Linux con nss-mdns resolvio
  `movil.local` y le hizo ping sin configuracion extra (getent + ping OK).
- Avahi -> Termux: `mdns browse` ve los servicios que publican equipos
  Avahi/Bonjour (SMB, SSH, _workstation, Chromecast, AirPlay...).
  Al usar zeroconf (RFC 6762/6763), Mac/Linux/Windows descubren y resuelven
  lo publicado y viceversa, sin cliente especial.

README: seccion de interoperabilidad, tabla RFC ampliada, ejemplos --watch
y --address. bashrc.snippet: alias mdns-watch. publish.py recortado a <100.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -49,7 +49,9 @@ Then follow the printed reminders (append `bashrc.snippet`, set your
 mdns resolve <host> [--family v4|v6] [--timeout 1.5] [--stale] [--no-cache]
 mdns reverse <ip>                            # PTR: IP -> hostname
 mdns browse [--type _svc._tcp.local.] [--json] [--list-types]
-mdns publish [--config ~/.config/mdns/services.json] [--hostname NAME]
+mdns browse --watch [--type ...] [--no-resolve]   # live monitor (avahi-browse -a)
+mdns publish [--config PATH] [--hostname NAME]     # services from JSON
+mdns publish --address <name> <ip>                 # bare A record (avahi-publish -a)
 mdns cache list | clear [host]
 ```
 
@@ -62,6 +64,8 @@ mdns resolve lenovo-ideapad                  # -> 192.168.1.106  (LAN, fast stdl
 mdns resolve lenovo-ideapad --family v6      # -> fe80::...      (via zeroconf)
 mdns reverse 192.168.1.17                    # -> dell-latitude3400.local
 mdns publish                                 # advertise services from ~/.config/mdns/services.json
+mdns publish --address printer 192.168.1.50  # publish printer.local -> that IP
+mdns browse --watch                          # live +/=/- events, all types
 mdns cache list                              # inspect TTL-aware cache
 ```
 
@@ -144,13 +148,38 @@ last-resort fallback.
 | A / AAAA hostname resolution     |   ✓    | stdlib for A, zeroconf for AAAA          |
 | PTR reverse lookup               |   ✓    | stdlib multicast, IPv4 + IPv6            |
 | DNS-SD service browsing          |   ✓    | `mdns browse`, all types or one          |
+| Live service monitor             |   ✓    | `mdns browse --watch` (like avahi-browse)|
 | Publisher (hostname + services)  |   ✓    | via `zeroconf`, with probing + goodbye   |
+| Bare hostname->IP publish        |   ✓    | `mdns publish --address` (avahi-publish -a)|
+| Name-conflict handling           |   ✓    | RFC 6762 probe + auto-rename             |
 | Multicast group membership       |   ✓    | `IP_ADD_MEMBERSHIP` on all sockets       |
 | Retries with backoff             |   ✓    | 2 attempts, split timeout                |
 | TTL-honoring cache               |   ✓    | JSON at `~/.cache/mdns/hosts.json`       |
 | Legacy unicast queries           |   —    | Not implemented (rarely needed)          |
 | Known-answer suppression         |   —    | zeroconf handles internally              |
 
+## Interoperability (Avahi / Bonjour)
+
+Because publishing goes through `zeroconf` (a full RFC 6762 / 6763
+implementation), anything you advertise is visible to standard mDNS stacks —
+**no special client needed on the other end**.
+
+Verified on a real LAN:
+
+- **Termux → Avahi (Linux):** with `mdns publish` running on the phone, a Linux
+  box with `nss-mdns` resolved `movil.local` and pinged it, with no extra config:
+  ```
+  $ getent hosts movil.local
+  192.168.1.112   movil.local
+  $ ping movil.local            # 64 bytes ... time=3.84 ms
+  ```
+- **Avahi → Termux:** `mdns browse` on the phone sees services published by
+  Avahi/Bonjour hosts (SMB, SSH, `_workstation`, Chromecast, AirPlay, …).
+
+So a Mac (Bonjour), a Linux box (Avahi), or a Windows machine (Bonjour Print
+Services) will all discover and resolve what this tool publishes, and vice
+versa.
+
 ## Gotchas found the hard way
 
 - **`getent` doesn't exist on Termux.** Scripts that shell out to it silently

bin/mdns

@@ -45,6 +45,10 @@ def _cmd_reverse(a: argparse.Namespace) -> int:
 
 
 def _cmd_browse(a: argparse.Namespace) -> int:
+    if a.watch:
+        from mdns_tools import watch as _w
+        _w.watch(service_type=a.type, resolve=not a.no_resolve)
+        return 0
     from mdns_tools import browse as _br  # loads zeroconf
     if a.list_types:
         for t in _br.list_types(duration=a.duration):
@@ -62,6 +66,9 @@ def _cmd_browse(a: argparse.Namespace) -> int:
 
 def _cmd_publish(a: argparse.Namespace) -> int:
     from mdns_tools import publish as _p  # loads zeroconf
+    if a.address:
+        _p.publish_address(a.address[0], a.address[1], verbose=not a.quiet)
+        return 0
     _p.run(config_path=a.config, hostname=a.hostname, verbose=not a.quiet)
     return 0
 
@@ -103,11 +110,17 @@ def main() -> int:
     b.add_argument("--duration", type=float, default=3.0)
     b.add_argument("--json", action="store_true")
     b.add_argument("--list-types", action="store_true")
+    b.add_argument("--watch", action="store_true",
+                   help="live monitor (+/=/- events) until Ctrl+C")
+    b.add_argument("--no-resolve", action="store_true",
+                   help="in --watch, don't resolve addresses")
     b.set_defaults(func=_cmd_browse)
 
     pu = sub.add_parser("publish", help="advertise this device + services")
-    pu.add_argument("--config", help="path to services YAML/JSON")
+    pu.add_argument("--config", help="path to services JSON")
     pu.add_argument("--hostname")
+    pu.add_argument("--address", nargs=2, metavar=("NAME", "IP"),
+                    help="publish a bare hostname->IP (A record), like avahi-publish -a")
     pu.add_argument("--quiet", action="store_true")
     pu.set_defaults(func=_cmd_publish)
 

config/bashrc.snippet

@@ -17,6 +17,7 @@ alias mdns-types='mdns browse --list-types'
 alias mdns-ssh='mdns browse --type _ssh._tcp.local.'
 alias mdns-smb='mdns browse --type _smb._tcp.local.'
 alias mdns-http='mdns browse --type _http._tcp.local.'
+alias mdns-watch='mdns browse --watch'
 alias mdns-cache='mdns cache list'
 alias mdns-forget='mdns cache clear'
 

lib/mdns_tools/publish.py

@@ -1,16 +1,10 @@
-"""Publish this device on the LAN: hostname + optional services.
+"""Publish on the LAN: services (JSON config) or a bare hostname->IP."""
-
+import json
-Config example (config/services.example.yaml or JSON):
-    hostname: movil
-    services:
-      - {type: _ssh._tcp, port: 8022, name: "Termux SSH"}
-      - {type: _smb._tcp, port: 4450, name: "Termux SMB"}
-"""
 import socket
 import time
 from pathlib import Path
 
-from zeroconf import Zeroconf, ServiceInfo
+from zeroconf import Zeroconf, ServiceInfo, NonUniqueNameException
 
 
 def _local_ipv4() -> str:
@@ -24,63 +18,34 @@ def _local_ipv4() -> str:
         s.close()
 
 
+def _addr_bytes(ip: str) -> bytes:
+    if ":" in ip:
+        return socket.inet_pton(socket.AF_INET6, ip)
+    return socket.inet_aton(ip)
+
+
+_DEFAULT_CONFIG = Path.home() / ".config" / "mdns" / "services.json"
+
+
 def _load_config(path: str | None) -> dict:
-    if not path:
+    p = Path(path).expanduser() if path else _DEFAULT_CONFIG
-        return {"hostname": "movil", "services": []}
-    p = Path(path).expanduser()
     if not p.exists():
         return {"hostname": "movil", "services": []}
-    text = p.read_text()
-    if p.suffix in (".yml", ".yaml"):
-        try:
-            import yaml  # type: ignore
-            return yaml.safe_load(text) or {}
-        except ImportError:
-            print("warning: PyYAML not installed, using minimal parser")
-    import json
     try:
-        return json.loads(text)
+        return json.loads(p.read_text())
-    except Exception:
+    except Exception as e:
+        print(f"warning: bad config {p}: {e}")
         return {"hostname": "movil", "services": []}
 
 
-def run(config_path: str | None = None,
+def _serve(zc: Zeroconf, infos: list[ServiceInfo], verbose: bool, label: str) -> None:
-        hostname: str | None = None,
+    for i in infos:
-        verbose: bool = True) -> None:
+        try:  # tolerate name conflicts per RFC 6762 (probe + rename)
-    """Publish hostname + services and block forever."""
+            zc.register_service(i)
-    cfg = _load_config(config_path)
+        except NonUniqueNameException:
-    host = hostname or cfg.get("hostname", "movil")
+            zc.register_service(i, allow_name_change=True)
-    ip = _local_ipv4()
-    zc = Zeroconf()
-    infos: list[ServiceInfo] = []
-    # Register hostname via _workstation._tcp so the device shows up in browsers
-    ws = ServiceInfo(
-        type_="_workstation._tcp.local.",
-        name=f"{host} [{ip.replace('.', '-')}]._workstation._tcp.local.",
-        addresses=[socket.inet_aton(ip)],
-        port=9,
-        server=f"{host}.local.",
-    )
-    zc.register_service(ws)
-    infos.append(ws)
-    for svc in (cfg.get("services") or []):
-        try:
-            t = svc["type"].rstrip(".") + ".local."
-            n = f'{svc.get("name", host)}.{t}'
-            info = ServiceInfo(
-                type_=t,
-                name=n,
-                addresses=[socket.inet_aton(ip)],
-                port=int(svc["port"]),
-                server=f"{host}.local.",
-                properties=svc.get("txt", {}),
-            )
-            zc.register_service(info)
-            infos.append(info)
-        except Exception as e:
-            print(f"warning: could not register {svc}: {e}")
     if verbose:
-        print(f"[mdns] published {host}.local ({ip}), {len(infos)} record(s). Ctrl+C to stop.")
+        print(f"[mdns] {label} ({len(infos)} record(s)). Ctrl+C to stop.")
     try:
         while True:
             time.sleep(60)
@@ -95,3 +60,37 @@ def run(config_path: str | None = None,
         zc.close()
         if verbose:
             print("[mdns] stopped, goodbye packets sent.")
+
+
+def _workstation(host: str, ip: str) -> ServiceInfo:
+    return ServiceInfo(
+        type_="_workstation._tcp.local.",
+        name=f"{host} [{ip.replace('.', '-')}]._workstation._tcp.local.",
+        addresses=[_addr_bytes(ip)], port=9, server=f"{host}.local.",
+    )
+
+
+def run(config_path: str | None = None, hostname: str | None = None,
+        verbose: bool = True) -> None:
+    cfg = _load_config(config_path)
+    host = hostname or cfg.get("hostname", "movil")
+    ip = _local_ipv4()
+    infos = [_workstation(host, ip)]
+    for svc in (cfg.get("services") or []):
+        try:
+            t = svc["type"].rstrip(".") + ".local."
+            infos.append(ServiceInfo(
+                type_=t, name=f'{svc.get("name", host)}.{t}',
+                addresses=[_addr_bytes(ip)], port=int(svc["port"]),
+                server=f"{host}.local.", properties=svc.get("txt", {}),
+            ))
+        except Exception as e:
+            print(f"warning: could not register {svc}: {e}")
+    _serve(Zeroconf(), infos, verbose, f"published {host}.local ({ip})")
+
+
+def publish_address(name: str, ip: str, verbose: bool = True) -> None:
+    """Publish a bare hostname -> IP mapping (like `avahi-publish -a`)."""
+    host = name.rstrip(".").removesuffix(".local")
+    _serve(Zeroconf(), [_workstation(host, ip)], verbose,
+           f"published {host}.local -> {ip}")

lib/mdns_tools/watch.py

@@ -0,0 +1,72 @@
+"""Live service monitor — like `avahi-browse` without -t.
+
+Prints events as they happen:
+    +  service appeared
+    =  service appeared and was resolved (address:port)
+    -  service disappeared
+
+With no --type it browses the DNS-SD meta-service
+(`_services._dns-sd._udp.local.`) to discover types dynamically and attaches a
+browser to each — the equivalent of `avahi-browse -a`.
+"""
+import time
+
+from zeroconf import Zeroconf, ServiceBrowser, ServiceListener
+
+
+class _EventListener(ServiceListener):
+    def __init__(self, resolve: bool = True) -> None:
+        self.resolve = resolve
+
+    def add_service(self, zc: Zeroconf, type_: str, name: str) -> None:  # noqa: N802
+        line = f"+ {type_:<30} {name}"
+        if self.resolve:
+            info = zc.get_service_info(type_, name, timeout=1500)
+            if info:
+                addrs = ", ".join(info.parsed_addresses() or []) or "-"
+                line = f"= {type_:<30} {name}  {addrs}:{info.port}"
+        print(line, flush=True)
+
+    def update_service(self, zc: Zeroconf, type_: str, name: str) -> None:  # noqa: N802
+        return
+
+    def remove_service(self, zc: Zeroconf, type_: str, name: str) -> None:  # noqa: N802
+        print(f"- {type_:<30} {name}", flush=True)
+
+
+class _TypeSpawner(ServiceListener):
+    """On discovering a new service TYPE, attach a browser for it."""
+
+    def __init__(self, zc: Zeroconf, svc_listener: ServiceListener) -> None:
+        self.zc = zc
+        self.svc_listener = svc_listener
+        self.browsers: dict[str, ServiceBrowser] = {}
+
+    def add_service(self, zc: Zeroconf, type_: str, name: str) -> None:  # noqa: N802
+        # For the meta-service, `name` is the discovered type (e.g. _http._tcp.local.)
+        if name not in self.browsers:
+            self.browsers[name] = ServiceBrowser(zc, name, self.svc_listener)
+
+    def update_service(self, *a) -> None:  # noqa: N802
+        return
+
+    def remove_service(self, *a) -> None:  # noqa: N802
+        return
+
+
+def watch(service_type: str | None = None, resolve: bool = True) -> None:
+    zc = Zeroconf()
+    svc = _EventListener(resolve=resolve)
+    try:
+        if service_type:
+            ServiceBrowser(zc, service_type, svc)
+        else:
+            ServiceBrowser(zc, "_services._dns-sd._udp.local.",
+                           _TypeSpawner(zc, svc))
+        print("[mdns] watching — Ctrl+C to stop", flush=True)
+        while True:
+            time.sleep(1)
+    except KeyboardInterrupt:
+        pass
+    finally:
+        zc.close()