fix(node): make ice_interfaces match adapters on Windows (W9)

`ice_interfaces` compared the operator's entry against ifaddr's
`adapter.name` only -- the kernel name on Linux (`wlp3s0f0`), but the adapter
GUID on Windows (`{846EE342-...}`). A setting written on Linux, or copied
into a Windows node's node.toml, matched no adapter at all.

The failure was silent and total rather than partial: aioice binds one socket
per host address, so an empty list means no sockets, no host candidates, and
an SDP offering only a reflexive address. The settings field is free text
with no picker, and on Windows the operator sees neither the GUID nor the
description -- `ipconfig` shows the connection name -- so an entry now
matches the adapter name, the device description, or one of the adapter's own
IPv4 addresses, case-insensitively. An address is the one identifier visible
on every platform.

A filter that matches nothing now falls back to the unfiltered list with a
warning. Losing the 5 s timeout saving is a regression; being silently
unconnectable is a defect.

Also fixes IPv4/IPv6 discrimination in the same loop: the two were told apart
by falling through to an `elif` that index-probed `ip.ip[0]` and `ip.ip[2]`,
which on an IPv4 str yields characters that compared unequal by luck rather
than by design. Now discriminated by isinstance.

WINDOWS-PORT.md claimed Transport had "no platform dependency"; it does.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DtfG7z6wHWj8RKHCvxQtY1

2 files changed, 104 insertions, 19 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/config.py b/packages/meshbay-node/src/meshbay_node/config.py
index 7be68a4..a5220cd 100644
--- a/packages/meshbay-node/src/meshbay_node/config.py
+++ b/packages/meshbay-node/src/meshbay_node/config.py
@@ -66,8 +66,12 @@ transcode_incompatible_video = true
 # ICE candidate gathering. By default, virtual/VPN interfaces (Tailscale,
 # libvirt, Docker) are auto-excluded — a STUN request that can't reach the
 # server holds the WebRTC answer for 5 seconds.  Set this to restrict
-# gathering to specific interfaces (by OS adapter name).
-# ice_interfaces = ["wlp0s20f3", "eth0"]
+# gathering to specific interfaces.  An entry matches the OS adapter name, the
+# device description, or one of the adapter's own IPv4 addresses, so a Windows
+# host can be named by description or address rather than by its GUID.  An
+# entry that matches nothing is ignored with a warning rather than leaving the
+# node with no candidates at all.
+# ice_interfaces = ["wlp0s20f3", "eth0", "192.168.1.22"]
 
 # STUN servers for WebRTC ICE candidate gathering (NAT traversal). By default
 # four public servers are used; set this to override. Every server in the list
diff --git a/packages/meshbay-node/src/meshbay_node/transport/ice_filter.py b/packages/meshbay-node/src/meshbay_node/transport/ice_filter.py
index a91724e..f0f369e 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/ice_filter.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/ice_filter.py
@@ -15,6 +15,24 @@ the interfaces the operator actually wants.  Two modes:
 
 Auto-excluded adapter name patterns: tailscale*, wt*, virbr*, docker*,
 veth*, br-*, podman*, cni*.
+
+Matching is "by adapter name", but an adapter does not have one name.  ifaddr
+reports `adapter.name` as the kernel name on Linux (`eth0`) and as a GUID on
+Windows (`{846EE342-7039-11DE-9D20-806E6F6E6963}`), while `adapter.nice_name`
+repeats the kernel name on Linux and carries the device *description* on
+Windows.  Neither is the connection name a Windows operator reads off
+`ipconfig` ("Ethernet", "Wi-Fi").  So an include-list entry is compared, case
+-insensitively, against the adapter's name, its nice_name, and its own IPv4
+addresses — an address is the one identifier visible on every platform, and
+the settings field is free text, so operators write whichever they can see.
+
+A filter that matches nothing is worse than no filter: aioice binds one socket
+per host address, so zero addresses means zero sockets, zero host candidates,
+and an ICE session that can only ever offer a server-reflexive address.  Behind
+two layers of NAT that address is unreachable for a peer on the intermediate
+LAN, so the connection cannot succeed at all — the failure looks like a network
+problem and is silent.  A filter that would return nothing therefore falls back
+to the unfiltered list and logs a warning: slow beats unreachable.
 """
 
 import ipaddress
@@ -42,41 +60,104 @@ def _is_cgnat(addr: str) -> bool:
         return False
 
 
+def _names(adapter) -> list[str]:
+    """Both identifiers ifaddr exposes; the same string twice on Linux."""
+    return [n for n in (adapter.name, adapter.nice_name) if isinstance(n, str)]
+
+
+def _ipv4s(adapter) -> list[str]:
+    return [ip.ip for ip in adapter.ips if isinstance(ip.ip, str)]
+
+
+def _is_virtual(adapter) -> bool:
+    return any(_VIRTUAL_ADAPTER_RE.match(n) for n in _names(adapter))
+
+
+def _matches(adapter, include_set: set[str]) -> bool:
+    """True if the operator named this adapter, however they spelled it."""
+    return any(
+        value.casefold() in include_set
+        for value in _names(adapter) + _ipv4s(adapter)
+    )
+
+
+def _addresses_of(adapter, use_ipv4: bool, use_ipv6: bool, *,
+                  drop_cgnat: bool) -> list[str]:
+    """
+    The usable addresses of one adapter.  ifaddr gives IPv4 as a str and IPv6
+    as an (address, flowinfo, scope_id) tuple, so the two are told apart by
+    type rather than by indexing — indexing a str yields characters, which
+    silently compare unequal to anything useful.
+    """
+    out: list[str] = []
+    for ip in adapter.ips:
+        if isinstance(ip.ip, str):
+            if not use_ipv4 or ip.ip == "127.0.0.1":
+                continue
+            if drop_cgnat and _is_cgnat(ip.ip):
+                continue
+            out.append(ip.ip)
+        elif isinstance(ip.ip, tuple) and len(ip.ip) >= 3:
+            # scope_id 0 == global; link-local needs a scope aioice has no use for
+            if use_ipv6 and ip.ip[0] != "::1" and ip.ip[2] == 0:
+                out.append(ip.ip[0])
+    return out
+
+
 def install(include: list[str] | None = None) -> None:
     """Monkey-patch aioice.ice.get_host_addresses with a filtered version."""
     import ifaddr
 
-    include_set = set(include) if include else None
+    include_set = {s.casefold() for s in include} if include else None
 
     def filtered_get_host_addresses(
         use_ipv4: bool = True, use_ipv6: bool = True,
     ) -> list[str]:
+        adapters = ifaddr.get_adapters()
         addresses: list[str] = []
-        for adapter in ifaddr.get_adapters():
+
+        for adapter in adapters:
             if include_set is not None:
-                if adapter.name not in include_set:
+                if not _matches(adapter, include_set):
                     continue
-            elif _VIRTUAL_ADAPTER_RE.match(adapter.name):
-                continue
+                # An explicitly named adapter is kept whatever its address range.
+                drop_cgnat = False
+            else:
+                if _is_virtual(adapter):
+                    continue
+                drop_cgnat = True
+            addresses.extend(
+                _addresses_of(adapter, use_ipv4, use_ipv6, drop_cgnat=drop_cgnat))
+
+        if addresses:
+            return addresses
 
-            for ip in adapter.ips:
-                if isinstance(ip.ip, str) and use_ipv4 and ip.ip != "127.0.0.1":
-                    if include_set is None and _is_cgnat(ip.ip):
-                        continue
-                    addresses.append(ip.ip)
-                elif use_ipv6 and ip.ip[0] != "::1" and ip.ip[2] == 0:
-                    addresses.append(ip.ip[0])
-        return addresses
+        # Nothing matched. Rather than gather no candidates at all, fall back to
+        # the unfiltered set — the operator loses the timeout saving, not the
+        # ability to connect.
+        fallback: list[str] = []
+        for adapter in adapters:
+            fallback.extend(
+                _addresses_of(adapter, use_ipv4, use_ipv6, drop_cgnat=False))
+        if fallback:
+            log.warning(
+                "ICE interface filter (%s) matched no address on this host; "
+                "using every interface instead. Adapters seen: %s",
+                "ice_interfaces=" + ", ".join(sorted(include)) if include
+                else "auto-exclude",
+                ", ".join(sorted({n for a in adapters for n in _names(a)})),
+            )
+        return fallback
 
     aioice.ice.get_host_addresses = filtered_get_host_addresses
 
     if include_set:
-        log.info("ICE interfaces (explicit): %s", ", ".join(sorted(include_set)))
+        log.info("ICE interfaces (explicit): %s", ", ".join(sorted(include)))
     else:
-        all_adapters = [a.name for a in ifaddr.get_adapters()]
         excluded = [
-            n for n in all_adapters
-            if _VIRTUAL_ADAPTER_RE.match(n)
+            a.nice_name or a.name
+            for a in ifaddr.get_adapters()
+            if _is_virtual(a)
         ]
         if excluded:
             log.info("ICE auto-excluded interfaces: %s", ", ".join(excluded))