Closes #15

changelog.md

@@ -6,6 +6,27 @@ existing Git tag; subsequent changes are listed as unreleased.
 
 ## Unreleased
 
+### 2026-10-13
+
+#### Added
+
+- `FrameDecodeStatus` distinguishes unknown frames, insufficient payloads,
+  signal errors, and successful decoding; frame `valid` still means matched.
+- `SignalDecodeStatus::PhysicalConversionFailed` reports NaN/Inf results,
+  retaining exact raw values and the non-finite physical result.
+- Regression tests for payload-length policy, partial results, invalid runtime
+  metadata, physical overflow/non-finite parameters, and raw branch selection
+  when selector physical conversion fails.
+
+#### Changed
+
+- Short payloads decode available signals without padding; longer payloads
+  ignore bytes beyond the declared DLC. Short frame status takes precedence
+  over signal errors, with per-signal causes retained in definition order.
+- Runtime signal validation checks enum values and bit layouts against declared
+  DLC using overflow-safe coordinates. Extra bytes cannot rescue invalid layouts.
+- Documented frame/signal status meanings, value availability, and payload policy.
+
 ### 2026-10-11
 
 #### Added