Support nested `wg` maddrs

Teach discovery to preserve WireGuard bearer and identity metadata
around a bindable TCP overlay.

Deats,
- encode `wg(8)` keys as strict 32-byte multibase values
- peel nested stacks with `Multiaddr.decapsulate_code()` and compose
  them with `.encapsulate()` instead of splitting strings
- integrate wrappers with `parse_maddr()`, `mk_maddr()`,
  `wrap_address()` and `parse_endpoints()`
- pin the unreleased py-multiaddr#108 codec in package metadata
- cover exact round trips, nesting, bad grammar and missing codecs

Prompt-IO: ai/prompt-io/opencode/20260818T075031Z_dd02c7c0_prompt_io.md

(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))

ai/prompt-io/opencode/20260818T075031Z_dd02c7c0_prompt_io.md

@@ -0,0 +1,50 @@
+---
+model: gpt-5.6-sol
+service: opencode
+session: tractor-addr-unpacking-followup
+timestamp: 2026-08-18T07:50:31Z
+git_ref: dd02c7c0
+scope: code
+substantive: true
+raw_file: 20260818T075031Z_dd02c7c0_prompt_io.raw.md
+---
+
+## Prompt
+
+The human requested the complete tunnelled-maddr parsing/composition
+slice as an unattended batch, with every numbered requirement finished
+and atomic commit plans prepared at the end. Existing human decisions
+required native `multiaddr` encapsulation APIs, no hand-written peeler,
+and preservation of tractor's future bindspace lifecycle ownership.
+
+## Response summary
+
+Implemented strict WG key codecs and native single/nested tunnel maddr
+parsing and composition, integrated them into discovery APIs, migrated
+the multihost example off its duplicate parser, corrected package
+dependency metadata, and added focused and end-to-end parser
+regressions. Verified the complete tractor suite and built both package
+artifacts.
+
+## Files changed
+
+- `tractor/discovery/` - WG codecs, parser/composer, wrapper typing,
+  public exports, and discovery dispatch.
+- `tests/discovery/` - key, grammar, nesting, round-trip, and public
+  boundary regressions.
+- `examples/multihost/wg_lan/` - production parser migration and
+  updated usage documentation.
+- `pyproject.toml`, `uv.lock` - reproducible WG codec and multibase
+  dependencies for checkout and package installs.
+- `ai/tpt-backends/03_wg_tunnel_bindspace.md` - current layer-A state
+  and future bindspace ownership.
+
+## Human edits
+
+The human selected the five-step scope and batch execution model,
+required delegation to `multiaddr`'s encapsulation APIs, rejected
+transport-shaped listener placeholders in the prerequisite commit, and
+clarified that tractor will eventually provision the kernel-owned
+bearer through its bindspace layer. The agent implemented and tested
+those decisions; no direct manual source edits were observed during
+this batch.

ai/prompt-io/opencode/20260818T075031Z_dd02c7c0_prompt_io.raw.md

@@ -0,0 +1,61 @@
+---
+model: gpt-5.6-sol
+service: opencode
+timestamp: 2026-08-18T07:50:31Z
+git_ref: dd02c7c0
+diff_cmd: git diff HEAD~1..HEAD
+---
+
+# Raw output - native WireGuard maddr integration
+
+The human requested completion of the five-step tunnelled-maddr slice:
+port the proven WireGuard parser, delegate to `py-multiaddr`'s native
+tunnel APIs, integrate public parse and composition entry points, add
+regressions, and return atomic commit plans after completing the batch.
+
+## Generated code
+
+> `git diff HEAD~1..HEAD -- tractor/discovery/_tunnel.py tractor/discovery/_multiaddr.py tractor/discovery/_addr.py tractor/discovery/__init__.py`
+
+Added strict WireGuard standard-base64/multibase key codecs and native
+WG maddr parsing/composition. Nested stacks peel the last `/wg/`
+repeatedly with `.decapsulate_code()`, isolate segments through
+`.split()`/`.join()`, and compose recursively with `.encapsulate()`.
+Public discovery parsing, wrapping, endpoint-table parsing, and maddr
+composition now preserve `TunnelledAddress` metadata locally.
+
+> `git diff HEAD~1..HEAD -- pyproject.toml uv.lock`
+
+Declared `py-multibase` directly and pinned the unreleased
+py-multiaddr#108 WG codec revision in distribution metadata. Enabled
+Hatch direct-reference metadata so editable, wheel, and sdist builds
+use the same dependency contract.
+
+> `git diff HEAD~1..HEAD -- tests/discovery/test_multiaddr.py tests/discovery/test_tunnelled_addr.py`
+
+Added key-codec, single/nested WG round-trip, malformed key, invalid
+bearer/overlay, missing codec, missing bearer, `wrap_address()`, and
+`parse_endpoints()` coverage while retaining plain TCP/UDS regressions.
+
+> `git diff HEAD~1..HEAD -- examples/multihost/wg_lan ai/tpt-backends/03_wg_tunnel_bindspace.md`
+
+Removed the duplicate example parser, migrated callers to production
+`TunnelledAddress`, retained only explicit `wg(8)` verification, and
+updated dependency and future bindspace ownership documentation.
+
+## Verification
+
+- focused discovery files: `45 passed`
+- discovery and IPC suites: `81 passed, 2 xpassed`
+- full suite: `443 passed, 9 skipped, 7 xfailed, 4 xpassed`
+- collection: `462 tests`
+- Ruff: clean
+- sdist and wheel builds: successful
+
+## Review corrections
+
+A review caught that `[tool.uv.sources]` alone would not constrain
+built-package consumers to a WG-capable py-multiaddr revision. The
+dependency was moved into PEP 621 metadata and the parser now converts
+missing-codec failures into an actionable tractor error without
+misclassifying Unix paths containing a `wg` directory.

pyproject.toml

@@ -48,7 +48,10 @@ dependencies = [
   # typed IPC msging
   "msgspec>=0.20.0",
   "bidict>=0.23.1",
-  "multiaddr>=0.2.0",
+  # unreleased `/wg/` codec from py-multiaddr#108
+  "multiaddr @ git+https://github.com/multiformats/py-multiaddr.git@f86519daaa21699023d0037c58cdff600313dd09",
+  # encode/decode `wg` pubkeys carried by multiaddrs
+  "py-multibase>=2.0.0,<3",
   "platformdirs>=4.4.0",
   # per-actor `argv[0]` proc-title for OS-level diag tools
   # (`ps`, `top`, `psutil`-backed tooling like `acli.pytree`).
@@ -166,17 +169,6 @@ sync_pause = {requires-python = ">=3.13, <3.14"}
 # linux kernel networking
 # 'pyroute2
 
-# XXX TEMP, the `/wg/u<key>` maddr proto is MERGED upstream (in
-# py-multiaddr#108, 2026-07-28) but is in NO release yet; the
-# latest `0.2.0` (2026-03-17) predates the merge by ~4 months.
-# Pinned by `rev` (not `branch`) so CI stays reproducible.
-#
-# Drop this pin (and bump the `multiaddr` dep floor above) the
-# moment a release carries the `wg` codec; the only consumer is
-# `examples/multihost/wg_lan/`.
-# |_https://github.com/multiformats/py-multiaddr/pull/108
-multiaddr = { git = 'https://github.com/multiformats/py-multiaddr.git', rev = 'f86519daaa21699023d0037c58cdff600313dd09' }
-
 # ------ tool.uv.sources ------
 
 [tool.uv]
@@ -191,6 +183,9 @@ python-preference = 'system'
 
 # ------ tool.uv ------
 
+[tool.hatch.metadata]
+allow-direct-references = true
+
 [tool.hatch.build.targets.sdist]
 include = ["tractor"]
 

tests/discovery/test_multiaddr.py

@@ -10,6 +10,14 @@ from types import SimpleNamespace
 import pytest
 from multiaddr import Multiaddr
 
+from tractor.discovery import (
+    TunnelledAddress,
+    WGTunnelSpec,
+    mb_pubkey,
+    mk_wg_maddr,
+    parse_wg_maddr,
+    tunnels_of,
+)
 from tractor.ipc._tcp import TCPAddress
 from tractor.ipc._uds import UDSAddress
 from tractor.discovery._multiaddr import (
@@ -22,6 +30,19 @@ from tractor.discovery._multiaddr import (
 from tractor.discovery._addr import wrap_address
 
 
+_WG_PUBKEY: str = (
+    'g3x7z0AdV1rM6UQU22CC7IL3/ivn4DzrE7ikDhCZ/Dc='
+)
+_WG_PUBKEY_2: str = (
+    'AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8='
+)
+_WG_MADDR: str = (
+    f'/ip4/192.168.1.50/udp/51820'
+    f'/wg/{mb_pubkey(_WG_PUBKEY)}'
+    f'/ip4/10.0.11.1/tcp/1616'
+)
+
+
 def test_tpt_proto_to_maddr_mapping():
     '''
     `_tpt_proto_to_maddr` maps all supported `proto_key`
@@ -210,6 +231,181 @@ def test_parse_maddr_unsupported():
         parse_maddr('/ip4/127.0.0.1/udp/1234')
 
 
+def test_parse_wg_maddr():
+    '''
+    `parse_maddr()` previously rejected the canonical infix `/wg/`
+    grammar even though `py-multiaddr` parsed it. Feed a bearer,
+    identity, and TCP overlay through both the WG-specific and public
+    parsers, then prove they produce the same local-only tunnel
+    annotation without changing the bindable overlay.
+
+    '''
+    parsed = parse_wg_maddr(_WG_MADDR)
+
+    assert parse_maddr(_WG_MADDR) == parsed
+    assert isinstance(parsed, TunnelledAddress)
+    assert parsed.tunnel == WGTunnelSpec(
+        peer_pubkey=_WG_PUBKEY,
+        bearer=('192.168.1.50', 51820),
+    )
+    assert isinstance(parsed.overlay, TCPAddress)
+    assert parsed.overlay.unwrap() == ('10.0.11.1', 1616)
+
+
+def test_mk_wg_maddr_roundtrip():
+    '''
+    `mk_maddr()` previously saw only the wrapper's delegated TCP
+    proto-key and silently dropped all tunnel metadata. Parse the
+    canonical maddr, compose it through both public entry points, and
+    prove bearer, key, and overlay survive byte-for-byte.
+
+    '''
+    parsed = parse_wg_maddr(_WG_MADDR)
+
+    assert str(mk_wg_maddr(parsed)) == _WG_MADDR
+    assert str(mk_maddr(parsed)) == _WG_MADDR
+
+
+def test_nested_wg_maddr_roundtrip():
+    '''
+    A single first-match lookup confuses nested WG keys and bearers.
+    Arrange an IPv4 outer bearer around an IPv6 inner bearer, parse
+    from the last `/wg/` outward, and assert tunnel ordering plus an
+    exact re-composition of the original stack.
+
+    '''
+    nested_maddr: str = (
+        f'/ip4/192.168.1.50/udp/51820'
+        f'/wg/{mb_pubkey(_WG_PUBKEY)}'
+        f'/ip6/2001:db8::2/udp/51821'
+        f'/wg/{mb_pubkey(_WG_PUBKEY_2)}'
+        f'/ip4/10.0.11.1/tcp/1616'
+    )
+
+    parsed = parse_maddr(nested_maddr)
+    specs = tunnels_of(parsed)
+
+    assert len(specs) == 2
+    assert specs[0].peer_pubkey == _WG_PUBKEY
+    assert specs[0].bearer == ('192.168.1.50', 51820)
+    assert specs[1].peer_pubkey == _WG_PUBKEY_2
+    assert specs[1].bearer == ('2001:db8::2', 51821)
+    assert str(mk_maddr(parsed)) == nested_maddr
+
+
+@pytest.mark.parametrize(
+    'maddr, match',
+    [
+        pytest.param(
+            (
+                f'/ip4/192.168.1.50/tcp/51820'
+                f'/wg/{mb_pubkey(_WG_PUBKEY)}'
+                f'/ip4/10.0.11.1/tcp/1616'
+            ),
+            'Bad `wg` bearer',
+            id='non-udp-bearer',
+        ),
+        pytest.param(
+            (
+                f'/ip4/192.168.1.50/udp/51820'
+                f'/wg/{mb_pubkey(_WG_PUBKEY)}'
+            ),
+            'no overlay endpoint',
+            id='missing-overlay',
+        ),
+        pytest.param(
+            (
+                f'/ip4/192.168.1.50/udp/51820'
+                f'/wg/{mb_pubkey(_WG_PUBKEY)}'
+                f'/ip4/10.0.11.1/udp/1616'
+            ),
+            'Unsupported `wg` overlay',
+            id='non-tcp-overlay',
+        ),
+    ],
+)
+def test_parse_wg_maddr_rejects_bad_grammar(
+    maddr: str,
+    match: str,
+):
+    '''
+    Accepting an invalid bearer or overlay assigns an endpoint to the
+    wrong runtime owner. Exercise parseable but unsupported protocol
+    combinations and prove each fails before constructing a wrapper,
+    with an error identifying the violated WG grammar boundary.
+
+    '''
+    with pytest.raises(ValueError, match=match):
+        parse_maddr(maddr)
+
+
+def test_parse_wg_maddr_rejects_malformed_key():
+    '''
+    A truncated multibase key used to be vulnerable to silent
+    identity corruption in hand-written parsers. Give the upstream
+    `/wg/` codec a short key and prove `Multiaddr()` rejects it
+    before tractor's wrapper parser runs.
+
+    '''
+    maddr: str = (
+        '/ip4/192.168.1.50/udp/51820'
+        '/wg/udG9vIHNob3J0'
+        '/ip4/10.0.11.1/tcp/1616'
+    )
+    with pytest.raises(ValueError):
+        parse_maddr(maddr)
+
+
+def test_parse_wg_maddr_reports_missing_codec(
+    monkeypatch,
+):
+    '''
+    Released `multiaddr==0.2.0` does not know `/wg/` and emits an
+    opaque unknown-protocol parse error. Simulate that registry and
+    prove an actual WG stack reports the dependency action while a
+    Unix path containing a `wg` directory remains ordinary UDS data.
+
+    '''
+    from multiaddr.exceptions import ProtocolNotFoundError
+    from tractor.discovery import _tunnel
+
+    def no_wg_proto(name: str):
+        raise ProtocolNotFoundError(name)
+
+    monkeypatch.setattr(
+        _tunnel,
+        'protocol_with_name',
+        no_wg_proto,
+    )
+    uds = parse_maddr('/unix/tmp/wg/service.sock')
+    assert isinstance(uds, UDSAddress)
+
+    with pytest.raises(
+        RuntimeError,
+        match='py-multiaddr#108',
+    ):
+        parse_maddr(_WG_MADDR)
+
+
+def test_mk_wg_maddr_requires_bearer():
+    '''
+    A key-only tunnel spec relies on local configuration and cannot
+    be reconstructed as the canonical bearer-first maddr. Build that
+    incomplete annotation and prove composition raises instead of
+    emitting a misleading overlay-only address.
+
+    '''
+    addr = TunnelledAddress(
+        overlay=TCPAddress('10.0.11.1', 1616),
+        tunnel=WGTunnelSpec(peer_pubkey=_WG_PUBKEY),
+    )
+    with pytest.raises(
+        ValueError,
+        match='without a bearer',
+    ):
+        mk_maddr(addr)
+
+
 @pytest.mark.parametrize(
     'addr',
     [
@@ -252,6 +448,21 @@ def test_wrap_address_maddr_str():
     assert result.unwrap() == ('127.0.0.1', 9999)
 
 
+def test_wrap_address_wg_maddr_str():
+    '''
+    `wrap_address()` delegates slash-prefixed strings to
+    `parse_maddr()`. Pass a canonical WG maddr through that public
+    boundary and prove it preserves the tunnel annotation rather than
+    rejecting the protocol stack or returning only its TCP overlay.
+
+    '''
+    result = wrap_address(_WG_MADDR)
+
+    assert isinstance(result, TunnelledAddress)
+    assert result.tunnel.peer_pubkey == _WG_PUBKEY
+    assert result.overlay.unwrap() == ('10.0.11.1', 1616)
+
+
 # ------ parse_endpoints() tests ------
 
 def test_parse_endpoints_tcp_only():
@@ -302,6 +513,30 @@ def test_parse_endpoints_mixed_tpts():
     assert str(filedir) == '/tmp/tractor'
 
 
+def test_parse_endpoints_wg_maddr():
+    '''
+    Service endpoint tables previously rejected WG protocol stacks.
+    Put a tunnelled maddr beside a plain TCP address and prove
+    `parse_endpoints()` retains input order while delivering the
+    wrapper needed by the future bindspace lifecycle.
+
+    '''
+    table = {
+        'registry': [
+            _WG_MADDR,
+            '/ip4/127.0.0.1/tcp/1616',
+        ],
+    }
+    addrs = parse_endpoints(table)['registry']
+
+    assert isinstance(addrs[0], TunnelledAddress)
+    assert addrs[0].tunnel.bearer == (
+        '192.168.1.50',
+        51820,
+    )
+    assert isinstance(addrs[1], TCPAddress)
+
+
 def test_parse_endpoints_unwrapped_tuples():
     '''
     `parse_endpoints()` accept raw `(host, port)` tuples

tests/discovery/test_tunnelled_addr.py

@@ -17,8 +17,10 @@ import pytest
 from tractor.discovery import (
     TunnelledAddress,
     WGTunnelSpec,
+    mb_pubkey,
     strip_tunnels,
     tunnels_of,
+    wg8_pubkey,
 )
 from tractor.discovery._addr import (
     is_wrapped_addr,
@@ -52,6 +54,54 @@ def tunnelled(
     return TunnelledAddress(overlay=overlay, tunnel=spec)
 
 
+def test_wg_pubkey_codec_roundtrip():
+    '''
+    Standard `wg(8)` base64 keys can contain `/`, which cannot be
+    embedded unchanged in a slash-delimited maddr. Prove the helper
+    emits `u`-prefixed multibase base64url without `/` and decodes
+    it back to the exact original 32-byte key.
+
+    '''
+    mb_key: str = mb_pubkey(_PUBKEY)
+
+    assert mb_key.startswith('u')
+    assert '/' not in mb_key
+    assert wg8_pubkey(mb_key) == _PUBKEY
+
+
+@pytest.mark.parametrize(
+    'key, converter',
+    [
+        pytest.param(
+            'dG9vIHNob3J0',
+            mb_pubkey,
+            id='wg8-base64',
+        ),
+        pytest.param(
+            'udG9vIHNob3J0',
+            wg8_pubkey,
+            id='multibase',
+        ),
+    ],
+)
+def test_wg_pubkey_codec_rejects_wrong_size(
+    key: str,
+    converter,
+):
+    '''
+    WireGuard silently-corrupt key handling would let an invalid
+    identity reach peer verification. Exercise both input encodings
+    with a short payload and prove conversion rejects it before a
+    tunnel spec or maddr can be constructed.
+
+    '''
+    with pytest.raises(
+        ValueError,
+        match='must decode to 32 bytes',
+    ):
+        converter(key)
+
+
 def test_proto_key_delegates(
     tunnelled: TunnelledAddress,
     overlay: TCPAddress,

tractor/discovery/__init__.py

@@ -33,6 +33,10 @@ from ._tunnel import (
     TunnelledAddress as TunnelledAddress,
     TunnelSpec as TunnelSpec,
     WGTunnelSpec as WGTunnelSpec,
+    mb_pubkey as mb_pubkey,
+    mk_wg_maddr as mk_wg_maddr,
+    parse_wg_maddr as parse_wg_maddr,
     strip_tunnels as strip_tunnels,
     tunnels_of as tunnels_of,
+    wg8_pubkey as wg8_pubkey,
 )

tractor/discovery/_addr.py

@@ -35,6 +35,7 @@ from ..ipc._tcp import TCPAddress
 from ..ipc._uds import UDSAddress
 
 if TYPE_CHECKING:
+    from ._tunnel import TunnelledAddress
     from ..runtime._runtime import Actor
 
 log = get_logger()
@@ -215,8 +216,8 @@ def mk_uuid() -> str:
 
 
 def wrap_address(
-    addr: UnwrappedAddress|str,
+    addr: UnwrappedAddress|str|Address|TunnelledAddress,
-) -> Address:
+) -> Address|TunnelledAddress:
     '''
     Wrap an `UnwrappedAddress` as an `Address`-type based
     on matching builtin python data-structures which we adhoc

tractor/discovery/_multiaddr.py

@@ -32,6 +32,7 @@ from multiaddr import Multiaddr
 
 if TYPE_CHECKING:
     from tractor.discovery._addr import Address
+    from tractor.discovery._tunnel import TunnelledAddress
 
 # map from tractor-internal `proto_key` identifiers
 # to the standard multiaddr protocol name strings.
@@ -48,7 +49,7 @@ _maddr_to_tpt_proto: dict[str, str] = {
 
 
 def mk_maddr(
-    addr: 'Address',
+    addr: 'Address|TunnelledAddress',
 ) -> Multiaddr:
     '''
     Construct a `Multiaddr` from a tractor `Address` instance,
@@ -56,6 +57,13 @@ def mk_maddr(
     multiaddr-spec-compliant protocol path.
 
     '''
+    from ._tunnel import (
+        TunnelledAddress,
+        mk_wg_maddr,
+    )
+    if isinstance(addr, TunnelledAddress):
+        return mk_wg_maddr(addr)
+
     proto_key: str = addr.proto_key
     maddr_proto: str|None = _tpt_proto_to_maddr.get(proto_key)
     if maddr_proto is None:
@@ -90,7 +98,7 @@ def mk_maddr(
 
 def parse_maddr(
     maddr_str: str,
-) -> 'Address':
+) -> 'Address|TunnelledAddress':
     '''
     Parse a multiaddr string into a tractor `Address`.
 
@@ -101,7 +109,16 @@ def parse_maddr(
     from tractor.ipc._tcp import TCPAddress
     from tractor.ipc._uds import UDSAddress
 
-    maddr = Multiaddr(maddr_str)
+    try:
+        maddr = Multiaddr(maddr_str)
+    except ValueError:
+        # Diagnose an unavailable WG codec after upstream parsing
+        # fails. Pre-checking the raw string would misclassify valid
+        # values such as `/unix/tmp/wg/service.sock`.
+        if '/wg/' in maddr_str:
+            from ._tunnel import _wg_proto_code
+            _wg_proto_code()
+        raise
     proto_names: list[str] = [
         p.name for p in maddr.protocols()
     ]
@@ -124,6 +141,10 @@ def parse_maddr(
                 filename=sockpath.name,
             )
 
+        case _ if 'wg' in proto_names:
+            from ._tunnel import parse_wg_maddr
+            return parse_wg_maddr(maddr)
+
         case _:
             raise ValueError(
                 f'Unsupported multiaddr protocol combo: '
@@ -142,11 +163,11 @@ EndpointsTable = dict[
     list[str|tuple],        # maddr strs or UnwrappedAddress
 ]
 
-# output table: actor/service name -> list of wrapped
+# output table: actor/service name -> list of wrapped address
-# `Address` instances ready for transport binding.
+# declarations ready for bindspace handling.
 ParsedEndpoints = dict[
     str,                    # actor/service name
-    list['Address'],
+    list['Address|TunnelledAddress'],
 ]
 
 
@@ -155,7 +176,7 @@ def parse_endpoints(
 ) -> ParsedEndpoints:
     '''
     Parse a service-endpoint config table into wrapped
-    `Address` instances suitable for transport binding.
+    address declarations suitable for bindspace handling.
 
     Each key is an actor/service name and each value is
     a list of addresses in any format accepted by
@@ -167,6 +188,8 @@ def parse_endpoints(
       ``/uds/`` proto_key)
     - raw unwrapped tuples: ``('127.0.0.1', 1616)``
     - pre-wrapped `Address` objects (passed through)
+    - `wg` maddrs, returned as `TunnelledAddress` wrappers which
+      must be peeled at the eventual bind/dial boundary
 
     Returns a new `dict` with the same keys, where each
     value list contains the corresponding `Address`

tractor/discovery/_tunnel.py

@@ -67,12 +67,18 @@ Unwrap at the parse or bindspace boundary; see `.overlay` and
 
 '''
 from __future__ import annotations
+import base64
+import ipaddress
 from typing import (
     ClassVar,
     TYPE_CHECKING,
 )
 
 import msgspec
+import multibase
+from multiaddr import Multiaddr
+from multiaddr.exceptions import ProtocolNotFoundError
+from multiaddr.protocols import protocol_with_name
 
 if TYPE_CHECKING:
     from ._addr import (
@@ -120,6 +126,68 @@ class WGTunnelSpec(
 TunnelSpec = WGTunnelSpec
 
 
+def mb_pubkey(
+    wg8_key: str,
+) -> str:
+    '''
+    Encode a `wg(8)` public key as multibase base64url.
+
+    WireGuard public keys are exactly 32 bytes. Enforce that here
+    before handing the `u`-prefixed result to `py-multiaddr`'s
+    `/wg/` codec.
+
+    '''
+    raw: bytes = base64.b64decode(
+        wg8_key,
+        validate=True,
+    )
+    if (nbytes := len(raw)) != 32:
+        raise ValueError(
+            f'A `wg` public key must decode to 32 bytes, '
+            f'not {nbytes}!'
+        )
+
+    return multibase.encode(
+        'base64url',
+        raw,
+    ).decode('ascii')
+
+
+def wg8_pubkey(
+    mb_key: str,
+) -> str:
+    '''
+    Decode a multibase public key to `wg(8)` standard base64.
+
+    '''
+    raw: bytes = multibase.decode(mb_key)
+    if (nbytes := len(raw)) != 32:
+        raise ValueError(
+            f'A `wg` public key must decode to 32 bytes, '
+            f'not {nbytes}!'
+        )
+
+    return base64.b64encode(raw).decode('ascii')
+
+
+def _wg_proto_code() -> int:
+    '''
+    Deliver the installed `py-multiaddr` `/wg/` protocol code.
+
+    `wg` support is merged upstream but not yet in a release, so
+    fail clearly when tractor was installed without the pinned rev.
+
+    '''
+    try:
+        return protocol_with_name('wg').code
+    except ProtocolNotFoundError as exc:
+        raise RuntimeError(
+            'Installed `py-multiaddr` has no `/wg/` protocol!\n'
+            'Install py-multiaddr#108 or use tractor\'s pinned '
+            'dependency revision.\n'
+        ) from exc
+
+
 class TunnelledAddress(
     msgspec.Struct,
     frozen=True,
@@ -128,14 +196,14 @@ class TunnelledAddress(
     An `Address` annotated with the tunnel it must be reached
     *through*.
 
-    Everything addressy delegates to `.overlay`, so every
+    Address-level properties delegate to `.overlay`, so proto-key
-    existing table lookup (`_addr_to_transport`, the
+    guards and `.unwrap()` retain their existing meaning and
-    `enable_transports` guard, `transport_from_addr()`) keeps
+    **nothing new crosses the wire**. Transport boundaries which
-    working untouched, and `.unwrap()` delegating means **nothing
+    dispatch on exact type or declaring module must first call
-    new crosses the wire**.
+    `strip_tunnels()`.
 
     '''
-    overlay: Address
+    overlay: Address|TunnelledAddress
     tunnel: TunnelSpec
 
     # ---- delegated, so the runtime can't tell the difference ----
@@ -205,6 +273,188 @@ class TunnelledAddress(
         )
 
 
+def _wg_bearer(
+    bearer_ma: Multiaddr,
+    source_ma: Multiaddr,
+) -> tuple[str, int]:
+    '''
+    Parse one kernel-owned `wg` bearer endpoint.
+
+    '''
+    proto_names: list[str] = [
+        proto.name
+        for proto in bearer_ma.protocols()
+    ]
+    match proto_names:
+        case [('ip4' | 'ip6') as ip_proto, 'udp']:
+            return (
+                bearer_ma.value_for_protocol(ip_proto),
+                int(bearer_ma.value_for_protocol('udp')),
+            )
+
+        case _:
+            raise ValueError(
+                f'Bad `wg` bearer, expected '
+                f'`/ip4|ip6/<host>/udp/<port>`\n'
+                f'got: {bearer_ma}\n'
+                f'from maddr: {source_ma}\n'
+            )
+
+
+def parse_wg_maddr(
+    maddr: str|Multiaddr,
+) -> TunnelledAddress:
+    '''
+    Parse a `wg` maddr stack into nested tunnel annotations.
+
+    Pure: every segment operation delegates to `py-multiaddr`.
+    Repeated `.decapsulate_code()` calls peel the last `/wg/`
+    first, while `.split()` and `.join()` isolate that tunnel's
+    bearer without parsing slash-delimited strings ourselves.
+
+    '''
+    ma: Multiaddr = (
+        maddr
+        if isinstance(maddr, Multiaddr)
+        else Multiaddr(maddr)
+    )
+    wg_code: int = _wg_proto_code()
+    segs: list[Multiaddr] = ma.split()
+    proto_names: list[str] = [
+        proto.name
+        for seg in segs
+        for proto in seg.protocols()
+    ]
+    if 'wg' not in proto_names:
+        raise ValueError(
+            f'Not a `wg`-tunnelled maddr; no `/wg/` segment!\n'
+            f'maddr: {ma}\n'
+        )
+
+    final_wg_i: int = len(proto_names) - 1
+    final_wg_i -= proto_names[::-1].index('wg')
+    overlay_ma: Multiaddr = Multiaddr.join(
+        *segs[final_wg_i + 1:]
+    )
+    overlay_names: list[str] = [
+        proto.name
+        for proto in overlay_ma.protocols()
+    ]
+    match overlay_names:
+        case [('ip4' | 'ip6'), 'tcp']:
+            from ._multiaddr import parse_maddr
+            overlay: Address|TunnelledAddress = parse_maddr(
+                str(overlay_ma)
+            )
+
+        case []:
+            raise ValueError(
+                f'`wg` maddr declares no overlay endpoint!\n'
+                f'Append the endpoint tractor should bind.\n'
+                f'maddr: {ma}\n'
+            )
+
+        case _:
+            raise ValueError(
+                f'Unsupported `wg` overlay protocol combo: '
+                f'{overlay_names!r}\n'
+                f'overlay: {overlay_ma}\n'
+                f'from maddr: {ma}\n'
+            )
+
+    cursor: Multiaddr = ma
+    while any(
+        proto.name == 'wg'
+        for proto in cursor.protocols()
+    ):
+        cursor_segs: list[Multiaddr] = cursor.split()
+        cursor_names: list[str] = [
+            proto.name
+            for seg in cursor_segs
+            for proto in seg.protocols()
+        ]
+        wg_i: int = len(cursor_names) - 1
+        wg_i -= cursor_names[::-1].index('wg')
+        mb_key: str = cursor_segs[wg_i].value_for_protocol('wg')
+
+        bearer_prefix: Multiaddr = cursor.decapsulate_code(
+            wg_code
+        )
+        prefix_segs: list[Multiaddr] = bearer_prefix.split()
+        prefix_names: list[str] = [
+            proto.name
+            for seg in prefix_segs
+            for proto in seg.protocols()
+        ]
+        prior_wg_i: int = (
+            len(prefix_names) - 1
+            - prefix_names[::-1].index('wg')
+            if 'wg' in prefix_names
+            else -1
+        )
+        bearer_ma: Multiaddr = Multiaddr.join(
+            *prefix_segs[prior_wg_i + 1:]
+        )
+        overlay = TunnelledAddress(
+            overlay=overlay,
+            tunnel=WGTunnelSpec(
+                peer_pubkey=wg8_pubkey(mb_key),
+                bearer=_wg_bearer(bearer_ma, ma),
+            ),
+        )
+        cursor = bearer_prefix
+
+    return overlay
+
+
+def mk_wg_maddr(
+    addr: TunnelledAddress,
+) -> Multiaddr:
+    '''
+    Compose nested tunnel annotations as a canonical `wg` maddr.
+
+    Only the peer key and bearer have maddr representations. Local
+    interface, namespace, and allowed-IP config remains local.
+
+    '''
+    _wg_proto_code()
+    if (bearer := addr.tunnel.bearer) is None:
+        raise ValueError(
+            f'Can not compose a `wg` maddr without a bearer!\n'
+            f'tunnel: {addr.tunnel!r}\n'
+        )
+
+    bindable: Address = strip_tunnels(addr)
+    if bindable.proto_key != 'tcp':
+        raise ValueError(
+            f'Unsupported `wg` overlay proto-key: '
+            f'{bindable.proto_key!r}\n'
+            f'overlay: {bindable!r}\n'
+        )
+
+    host, port = bearer
+    ip = ipaddress.ip_address(host)
+    ip_proto: str = (
+        'ip4'
+        if ip.version == 4
+        else 'ip6'
+    )
+    bearer_ma = Multiaddr(
+        f'/{ip_proto}/{host}/udp/{port}'
+    )
+    key_ma = Multiaddr(
+        f'/wg/{mb_pubkey(addr.tunnel.peer_pubkey)}'
+    )
+
+    from ._multiaddr import mk_maddr
+    overlay_ma: Multiaddr = mk_maddr(addr.overlay)
+    return (
+        bearer_ma
+        .encapsulate(key_ma)
+        .encapsulate(overlay_ma)
+    )
+
+
 def strip_tunnels(
     addr: Address|TunnelledAddress,
 ) -> Address:

uv.lock

@@ -1113,6 +1113,7 @@ dependencies = [
     { name = "multiaddr" },
     { name = "pdbp" },
     { name = "platformdirs" },
+    { name = "py-multibase" },
     { name = "setproctitle" },
     { name = "tricycle" },
     { name = "trio" },
@@ -1177,6 +1178,7 @@ requires-dist = [
     { name = "multiaddr", git = "https://github.com/multiformats/py-multiaddr.git?rev=f86519daaa21699023d0037c58cdff600313dd09" },
     { name = "pdbp", specifier = ">=1.8.2,<2" },
     { name = "platformdirs", specifier = ">=4.4.0" },
+    { name = "py-multibase", specifier = ">=2.0.0,<3" },
     { name = "setproctitle", specifier = ">=1.3,<2" },
     { name = "tricycle", specifier = ">=0.4.1,<0.5" },
     { name = "trio", specifier = ">0.27" },