feat(log): add bounded diagnostic transport

libs/kaptan-log-mavlink/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "kaptan-log-mavlink"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+rust-version.workspace = true
+version.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+kaptan-log = { path = "../kaptan-log" }
+kaptan-mavlink = { path = "../kaptan-mavlink", default-features = false, features = ["dialect-kaptan"] }
+
+[dev-dependencies]
+kaptan-log = { path = "../kaptan-log", features = ["facade"] }
+mavlink = { version = "0.18", default-features = false, features = ["embedded"] }

libs/kaptan-log-mavlink/src/lib.rs

@@ -0,0 +1,195 @@
+//! MAVLink projection for bounded Kaptan diagnostics.
+//!
+//! This adapter creates generated payload data only. A platform-owned link is
+//! solely responsible for MAVLink header sequence, bounded admission, DMA, and
+//! retry policy.
+
+#![no_std]
+
+#[cfg(test)]
+extern crate std;
+
+use kaptan_log::{LogRecord, RecordChannel, ShutdownReason, ShutdownReport};
+use kaptan_mavlink::message::kaptan::{
+    KAPTAN_ERROR_DATA, KAPTAN_LOG_DATA, KAPTAN_SHUTDOWN_DATA, KaptanErrorFlags, KaptanLogFlags,
+    KaptanShutdownReason,
+};
+
+/// Exact capacity of the fixed text field in [`KAPTAN_LOG_DATA`].
+pub const LOG_MESSAGE_BYTES: usize = 160;
+
+/// One generated diagnostic payload. A platform-owned link remains the sole
+/// MAVLink framing, admission, DMA, and retry owner.
+#[derive(Clone, Debug, PartialEq)]
+pub enum DiagnosticPayload {
+    /// Ordinary severity-and-text record.
+    Log(KAPTAN_LOG_DATA),
+    /// Error-only bounded display identity.
+    Error(KAPTAN_ERROR_DATA),
+}
+
+/// Encodes one bounded diagnostic record.
+///
+/// The adapter produces payload data only; it neither frames nor transmits
+/// MAVLink. `RecordChannel` is the only routing decision: ordinary records
+/// become `KAPTAN_LOG`, while error-or-higher records become `KAPTAN_ERROR`.
+pub fn encode_diagnostic(record: &LogRecord) -> DiagnosticPayload {
+    let message = record.message();
+    debug_assert!(usize::from(message.len()) <= LOG_MESSAGE_BYTES);
+    match record.channel() {
+        RecordChannel::Log => DiagnosticPayload::Log(KAPTAN_LOG_DATA {
+            level: record.severity() as u8,
+            flags: KaptanLogFlags::from_bits_retain(record.flags().bits()),
+            message_length: message.len(),
+            message: *message.bytes(),
+        }),
+        RecordChannel::Error => DiagnosticPayload::Error(KAPTAN_ERROR_DATA {
+            flags: KaptanErrorFlags::from_bits_retain(record.flags().error_bits()),
+            message_length: message.len(),
+            message: *message.bytes(),
+        }),
+    }
+}
+
+/// Encodes one typed shutdown event. The caller owns when a shutdown is safe
+/// to report; this pure adapter cannot run a shutdown state machine.
+pub const fn encode_shutdown(report: ShutdownReport) -> KAPTAN_SHUTDOWN_DATA {
+    KAPTAN_SHUTDOWN_DATA {
+        reason: match report.reason() {
+            ShutdownReason::Operator => KaptanShutdownReason::KAPTAN_SHUTDOWN_REASON_OPERATOR,
+            ShutdownReason::Safety => KaptanShutdownReason::KAPTAN_SHUTDOWN_REASON_SAFETY,
+        },
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Once;
+
+    use super::{DiagnosticPayload, LOG_MESSAGE_BYTES, encode_diagnostic, encode_shutdown};
+    use kaptan_log::{
+        EventHub, FacadeIngress, GlobalLogger, LogFilter, LogFlags, LogRecord, LogText, Severity,
+        ShutdownReason, ShutdownReport,
+    };
+    use kaptan_mavlink::{
+        encoder::MavlinkEncoder,
+        message::{
+            Message,
+            kaptan::{KAPTAN_ERROR_DATA, KAPTAN_LOG_DATA, KAPTAN_SHUTDOWN_DATA, MavMessage},
+        },
+    };
+
+    static ERROR_INGRESS: FacadeIngress<1> = FacadeIngress::new(LogFilter::new(Severity::Info));
+    static ERROR_LOGGER: GlobalLogger<1> = GlobalLogger::new(&ERROR_INGRESS, never_forbidden);
+    static INSTALL_ERROR_LOGGER: Once = Once::new();
+
+    const fn never_forbidden() -> bool {
+        false
+    }
+
+    #[test]
+    fn ordinary_record_preserves_level_flags_and_bounded_text() {
+        let record = LogRecord::new(
+            Severity::Info,
+            LogFlags::TRUNCATED,
+            LogText::from_message("imu unavailable"),
+        );
+        let DiagnosticPayload::Log(data) = encode_diagnostic(&record) else {
+            panic!("info record must use KAPTAN_LOG");
+        };
+        assert_eq!(data.level, Severity::Info as u8);
+        assert_eq!(data.message_length, 15);
+        assert_eq!(&data.message[..15], b"imu unavailable");
+        assert!(data.message[15..].iter().all(|byte| *byte == 0));
+        assert_eq!(data.flags.bits(), LogFlags::TRUNCATED.bits());
+        assert_eq!(KAPTAN_LOG_DATA::ENCODED_LEN, 163);
+    }
+
+    #[test]
+    fn standard_error_macro_reaches_error_channel_after_optional_ingress_is_full() {
+        INSTALL_ERROR_LOGGER.call_once(|| {
+            ERROR_LOGGER
+                .install()
+                .expect("the test owns the process-global log facade");
+        });
+
+        kaptan_log::log::info!("optional ingress is occupied");
+        kaptan_log::log::error!("critical error survives");
+
+        let mut hub = EventHub::<1, 1>::new(LogFilter::default());
+        assert!(ERROR_INGRESS.drain_one_into(&mut hub).is_some());
+        let record = hub.peek().expect("critical macro record retained");
+        let DiagnosticPayload::Error(payload) = encode_diagnostic(&record) else {
+            panic!("log::error! must not produce KAPTAN_LOG");
+        };
+        assert!(
+            payload.message[..usize::from(payload.message_length)]
+                .ends_with(b"critical error survives")
+        );
+    }
+
+    #[test]
+    fn generated_log_and_error_messages_round_trip_through_the_sole_encoder() {
+        let record = LogRecord::new(
+            Severity::Info,
+            LogFlags::NONE,
+            LogText::from_message(&"x".repeat(LOG_MESSAGE_BYTES)),
+        );
+        let DiagnosticPayload::Log(data) = encode_diagnostic(&record) else {
+            panic!("info record must use KAPTAN_LOG");
+        };
+        let mut encoder = MavlinkEncoder::new(1, 1);
+        let frame = encoder.custom(&data);
+        assert!(frame.has_valid_crc::<MavMessage>());
+        assert_eq!(frame.message_id(), 51_020);
+        assert_eq!(frame.raw_bytes().len(), 175);
+        match MavMessage::parse(
+            mavlink::MavlinkVersion::V2,
+            frame.message_id(),
+            frame.payload(),
+        ) {
+            Ok(MavMessage::KAPTAN_LOG(decoded)) => assert_eq!(decoded, data),
+            other => panic!("unexpected decoded KAPTAN_LOG payload: {other:?}"),
+        }
+        assert_eq!(data.message.len(), LOG_MESSAGE_BYTES);
+
+        let error = LogRecord::new(
+            Severity::Error,
+            LogFlags::TRACE.with(LogFlags::COALESCED),
+            LogText::from_message("driver::Error::Transfer"),
+        );
+        let DiagnosticPayload::Error(error_data) = encode_diagnostic(&error) else {
+            panic!("error record must use KAPTAN_ERROR");
+        };
+        assert_eq!(error_data.flags.bits(), LogFlags::COALESCED.bits());
+        assert_eq!(error_data.message_length, 23);
+        assert_eq!(KAPTAN_ERROR_DATA::ENCODED_LEN, 162);
+        let error_frame = encoder.custom(&error_data);
+        assert_eq!(error_frame.message_id(), 51_021);
+        assert!(matches!(
+            MavMessage::parse(
+                mavlink::MavlinkVersion::V2,
+                error_frame.message_id(),
+                error_frame.payload(),
+            ),
+            Ok(MavMessage::KAPTAN_ERROR(decoded)) if decoded == error_data
+        ));
+    }
+
+    #[test]
+    fn typed_shutdown_maps_to_its_sole_generated_message() {
+        let data = encode_shutdown(ShutdownReport::new(ShutdownReason::Safety));
+        assert_eq!(KAPTAN_SHUTDOWN_DATA::ENCODED_LEN, 1);
+        let mut encoder = MavlinkEncoder::new(1, 1);
+        let frame = encoder.custom(&data);
+        assert_eq!(frame.message_id(), 51_022);
+        assert!(matches!(
+            MavMessage::parse(
+                mavlink::MavlinkVersion::V2,
+                frame.message_id(),
+                frame.payload(),
+            ),
+            Ok(MavMessage::KAPTAN_SHUTDOWN(decoded)) if decoded == data
+        ));
+    }
+}