feat(v2): nostr-transport roster-resolver hook (#20 path-B)

Exposes `resolve(sender_pubkey_hex) -> RouteHit | None` and a
`register_with_lnbits()` helper that lazily-imports + soft-fails on
lnbits versions without `register_roster_resolver`. Wired into
`satmachineadmin_start()`.

The hook delivers the path-B outcome ("cash-out sats go to the
operator's wallet, not an auto-created machine wallet") once the
lnbits side ships its half. Shape contract `(operator_user_id,
wallet_id, source_extension)` frozen per coord-log 2026-05-31T15:25Z.
Branch held local until lnbits lands the registry — no behaviour
change on the current lnbits version, just the future-ready handoff
+ a benign INFO log on boot.

Boot-smoked in dev container: extension loads, registration logs the
documented soft-fail message, invoice listener + cassette consumer
unchanged. 6 new unit tests cover happy path, miss, bech32 +
uppercase canonicalisation, fail-closed on malformed input, and the
soft-fail register branch.

tests/test_roster_resolver.py

@@ -0,0 +1,163 @@
+"""
+Tests for `nostr_transport_roster.resolve` — the lookup function
+satmachineadmin hands lnbits' nostr-transport via
+`register_roster_resolver` (path-B wallet-routing fix, #20 /
+coord-log 2026-05-31T15:25Z).
+
+Verifies:
+  - Known ATM npub → RouteHit with operator_user_id + wallet_id from
+    the machine row
+  - Unknown sender → None (lnbits falls back to its other resolvers,
+    or fail-closed rejection per the env-gated posture)
+  - bech32 input is normalised to hex before lookup
+  - Uppercase hex input is normalised to lowercase before lookup
+  - Malformed input raises (fail-closed sub-case per lnbits 15:15Z ack)
+
+`register_with_lnbits` is also smoke-tested for the soft-fail branch
+that fires on lnbits versions without `register_roster_resolver`. The
+positive (lnbits hook present) branch needs a live lnbits import +
+will be covered once the lnbits-side PR lands.
+
+Coroutines driven via `asyncio.run` per project convention (no pytest-
+asyncio plugin in CI; see test_cassette_state_consumer.py header).
+"""
+
+import asyncio
+import sys
+from types import SimpleNamespace
+
+import coincurve
+import pytest
+from lnbits.utils.nostr import hex_to_npub
+
+from .. import nostr_transport_roster as roster
+from ..nostr_transport_roster import register_with_lnbits, resolve
+
+_ATM_SEC = "00" * 31 + "02"
+_ATM_PUB_HEX = (
+    coincurve.PrivateKey(bytes.fromhex(_ATM_SEC))
+    .public_key.format(compressed=True)[1:]
+    .hex()
+)
+_ATM_PUB_NPUB = hex_to_npub(_ATM_PUB_HEX)
+
+
+def _fake_machine(operator_user_id: str, wallet_id: str, npub_hex: str):
+    return SimpleNamespace(
+        operator_user_id=operator_user_id,
+        wallet_id=wallet_id,
+        machine_npub=npub_hex,
+    )
+
+
+def test_resolve_known_atm_returns_route_hit(monkeypatch):
+    captured: dict[str, str] = {}
+
+    async def _fake_lookup(pubkey_hex: str):
+        captured["pubkey_hex"] = pubkey_hex
+        return _fake_machine(
+            operator_user_id="op-123",
+            wallet_id="wallet-abc",
+            npub_hex=_ATM_PUB_HEX,
+        )
+
+    monkeypatch.setattr(roster, "get_machine_by_atm_pubkey_hex", _fake_lookup)
+
+    result = asyncio.run(resolve(_ATM_PUB_HEX))
+
+    # `_build_route_hit` prefers lnbits' canonical `RouteHit` when
+    # importable + falls back to our local class otherwise; assert on
+    # the frozen field-shape contract (coord-log 2026-05-31T15:25Z),
+    # not the specific class identity, so the test passes against
+    # both lnbits versions.
+    assert result is not None
+    assert result.operator_user_id == "op-123"
+    assert result.wallet_id == "wallet-abc"
+    assert result.source_extension == "satmachineadmin"
+    assert captured["pubkey_hex"] == _ATM_PUB_HEX
+
+
+def test_resolve_unknown_sender_returns_none(monkeypatch):
+    async def _no_match(pubkey_hex: str):
+        return None
+
+    monkeypatch.setattr(roster, "get_machine_by_atm_pubkey_hex", _no_match)
+
+    result = asyncio.run(resolve(_ATM_PUB_HEX))
+
+    assert result is None
+
+
+def test_resolve_canonicalises_bech32_to_hex(monkeypatch):
+    """Sender pubkeys arrive lowercase-hex from lnbits PR #4, but the
+    resolver is paranoid: a bech32 input must still hit the hex-keyed
+    crud lookup."""
+    captured: dict[str, str] = {}
+
+    async def _fake_lookup(pubkey_hex: str):
+        captured["pubkey_hex"] = pubkey_hex
+        return _fake_machine(
+            operator_user_id="op-bech32",
+            wallet_id="wallet-bech32",
+            npub_hex=_ATM_PUB_HEX,
+        )
+
+    monkeypatch.setattr(roster, "get_machine_by_atm_pubkey_hex", _fake_lookup)
+
+    result = asyncio.run(resolve(_ATM_PUB_NPUB))
+
+    assert result is not None
+    assert captured["pubkey_hex"] == _ATM_PUB_HEX
+
+
+def test_resolve_lowercases_uppercase_hex(monkeypatch):
+    captured: dict[str, str] = {}
+
+    async def _fake_lookup(pubkey_hex: str):
+        captured["pubkey_hex"] = pubkey_hex
+        return None
+
+    monkeypatch.setattr(roster, "get_machine_by_atm_pubkey_hex", _fake_lookup)
+
+    asyncio.run(resolve(_ATM_PUB_HEX.upper()))
+
+    assert captured["pubkey_hex"] == _ATM_PUB_HEX
+
+
+def test_resolve_raises_on_malformed_input(monkeypatch):
+    """Fail-closed sub-case per lnbits 15:15Z ack item 2: resolver
+    raising an exception surfaces to lnbits as a reject + ERROR log,
+    NOT a silent fall-through to auto-account creation."""
+
+    async def _unreachable(pubkey_hex: str):
+        raise AssertionError("crud must not be reached for malformed input")
+
+    monkeypatch.setattr(roster, "get_machine_by_atm_pubkey_hex", _unreachable)
+
+    with pytest.raises((ValueError, AssertionError)):
+        asyncio.run(resolve("not-a-pubkey"))
+
+
+def test_register_with_lnbits_soft_fails_without_hook(monkeypatch):
+    """Until the lnbits-side path-B PR lands, the registration call
+    must soft-fail cleanly (returns False, no exception) so
+    satmachineadmin keeps booting on every lnbits version."""
+    real_import = (
+        __builtins__["__import__"]
+        if isinstance(__builtins__, dict)
+        else __builtins__.__import__
+    )
+
+    def _faulty_import(name, *args, **kwargs):
+        if name == "lnbits.core.services.nostr_transport":
+            raise ImportError("simulated: pre-path-B lnbits")
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr("builtins.__import__", _faulty_import)
+    # Drop any cached import so the lazy `from … import …` inside
+    # register_with_lnbits re-triggers the import statement.
+    monkeypatch.delitem(
+        sys.modules, "lnbits.core.services.nostr_transport", raising=False
+    )
+
+    assert register_with_lnbits() is False