fix(tests): gate on firmware capability, not host bindings or source text - #52

Two gates checked something other than what they claimed, and both went green on a branch where the thing they gate is absent.

requires_message() can never fail

It asks whether python-keepkey's own bindings define a message. That is a property of the pinned submodule, not of the firmware under test — so it passes on every branch regardless of what the device implements.

The structured EIP-712 suite relied on it. On feat/passkeys-7.16, which has no eip712_stream.c at all, four tests failed as though the feature were broken rather than absent.

Replaced with requires_structured_eip712(), which probes the device. Firmware without the walk answers the opening message with Failure_UnexpectedMessage.

Deliberately, any other Failure does not skip — the test runs and reports. "Present but misbehaving" must never be mistaken for "absent"; that is how a skipped test becomes a silent pass, which has already cost us once.

test_burned_versions_have_no_reader asserted the wrong thing

It asserted the absence of a case StorageVersion_18: label, on the theory that falling through to the default is what sends a burned format to the wipe path.

There is no default. storage_fromFlash omits one deliberately so that -Werror=switch names any version we forget. So an unlisted version does not fall anywhere — it breaks the ARM build, which is exactly what happened on the passkey branch.

The labels must exist. What must not exist is a reader behind them. The test now asserts that real property: 18 and 19 are dispatched, and what they dispatch to is SUS_Invalid with no storage_readVxx call in the arm.

Verified not vacuous — injecting storage_readV17 behind the burned labels makes it fail:

E             return SUS_Updated;
test_storage_version_gate.py:494: AssertionError
FAILED test_storage_version_gate.py::TestStorageVersionGateSource::test_burned_versions_are_dispatched_to_the_wipe_path

Verification

test_storage_version_gate.py: 5 passed, 4 skipped, run locally. The EIP-712 gate needs a device and is exercised by firmware CI.