refactor(firmware): centralize configuration and diagnostics

firmware/libs/kaptan-mavlink/src/transmitter.rs

@@ -18,32 +18,10 @@ pub enum MavlinkTransmitFault<MemoryError, EngineError> {
     Engine(EngineError),
 }
 
-/// Transport-neutral class of a terminal link fault.
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
-pub enum TransmitFaultKind {
-    /// DMA-visible frame preparation failed.
-    Memory,
-    /// The UART DMA engine rejected a transfer start.
-    Engine,
-    /// An active DMA transfer ended with a terminal fault or halt.
-    Terminal,
-}
-
-impl<MemoryError, EngineError> MavlinkTransmitFault<MemoryError, EngineError> {
-    /// Returns the bounded category a platform may convert to a static log
-    /// message without exposing a generic HAL error value on the wire.
-    pub const fn kind(&self) -> TransmitFaultKind {
-        match self {
-            Self::Memory(_) => TransmitFaultKind::Memory,
-            Self::Engine(_) => TransmitFaultKind::Engine,
-        }
-    }
-}
-
 /// Combined bounded-admission and DMA-start outcome.
 ///
-/// The two outcomes stay distinct so a platform can account for a failed DMA
-/// start without falsely treating a queue-full source frame as retained.
+/// The outcomes stay distinct because admission decides whether the source may
+/// acknowledge its frame, while a failed start keeps reserved work for retry.
 #[must_use]
 pub struct AdmissionStart<MemoryError, EngineError> {
     /// Queue admission for the source frame.
@@ -94,10 +72,9 @@ where
     }
 
     /// Admits one frame and attempts one bounded DMA start while preserving
-    /// both outcomes. Platform policy uses this to account for a failed DMA
-    /// start without mistaking an admission rejection for a retained frame.
-    /// A start failure retains the selected frame in the queue reservation for
-    /// a later service-turn retry.
+    /// both outcomes. A start failure retains the selected frame in the queue
+    /// reservation for a later service-turn retry; it does not change whether
+    /// the newly submitted source frame was admitted.
     pub fn admit_and_start(
         &mut self,
         class: FrameClass,