FFI driver

Engineering TagSource enum has no ffi. Runtime snapshot / CompiledSource JSON:

json

{ "protocol": "ffi", "libraryPath": "C:\\path\\driver.dll" }

(host may be a backward-compatible alias for the path.)

ABI

Frozen C header: crates/driver-sdk / include/mdv_driver_v1.h
MDV_DRIVER_ABI_VERSION 1
drivers/ffi-bridge: libloading → mdv_driver_create_v1, configure/start/poll, stop+unload on Drop
Example: drivers/ffi-bridge/examples/example_driver.c (single f64 = 21.5)
Helper: ffi-host binary

Write (operate) is not supported. Empty path / missing symbol → tag bad quality; HTTP does not crash.

Field drivers today are Rust and do not use this ABI.