added capture time for every sweep

data_acq_and_processing/common_cpp/ipc/include/shared_types.hpp

@@ -38,6 +38,13 @@ struct SweepTraceBlock {
     std::vector<Complex32> s11{};
     // Complex S21 samples for matching frequency points.
     std::vector<Complex32> s21{};
+    // Monotonic window in which THIS trace's sweep was measured, excluding the
+    // switch drive and settling that preceded it. In a switched matrix the
+    // collection is assembled combo by combo over many milliseconds, so the
+    // collection-level window says nothing about when an individual combo was
+    // measured. Zero on both is a valid "unmeasured" sentinel.
+    std::uint64_t capture_start_ns = 0;
+    std::uint64_t capture_end_ns = 0;
 };
 
 struct RawSweepCollection {

data_acq_and_processing/common_cpp/ipc/src/shared_types.cpp

@@ -172,6 +172,10 @@ void require_count_fits(std::uint32_t count, std::size_t min_bytes_each, BinaryR
     return trace;
 }
 
+// The capture windows live in a TRAILER after the trace blocks rather than inside
+// them, so a reader built before they existed still decodes every trace and simply
+// stops early. The trailer grows the same way: collection window first, then the
+// per-trace window table (one pair per trace, in trace order).
 void write_trace_collection(BinaryWriter& writer, std::uint32_t magic, const RawSweepCollection& collection) {
     writer.write(magic);
     writer.write(collection.collection_id);
@@ -184,6 +188,12 @@ void write_trace_collection(BinaryWriter& writer, std::uint32_t magic, const Raw
 
     writer.write(collection.capture_start_ns);
     writer.write(collection.capture_end_ns);
+
+    writer.write(checked_count_to_u32(collection.traces.size(), "Trace capture window count"));
+    for (const auto& trace : collection.traces) {
+        writer.write(trace.capture_start_ns);
+        writer.write(trace.capture_end_ns);
+    }
 }
 
 [[nodiscard]] auto read_trace_collection(BinaryReader& reader, std::uint32_t expected_magic) -> RawSweepCollection {
@@ -204,16 +214,31 @@ void write_trace_collection(BinaryWriter& writer, std::uint32_t magic, const Raw
         collection.traces.push_back(read_trace_block(reader));
     }
 
+    // Each trailer stage is optional: a payload from an older producer stops after
+    // the trace blocks (or after the collection window) and leaves the rest zeroed.
     if (reader.remaining_bytes() == 0U) {
         return collection;
     }
-    if (reader.remaining_bytes() != (sizeof(std::uint64_t) * 2U)) {
-        throw std::runtime_error("Unexpected trailing bytes in trace collection");
+    if (reader.remaining_bytes() < (sizeof(std::uint64_t) * 2U)) {
+        throw std::runtime_error("Truncated capture window in trace collection");
     }
 
     collection.capture_start_ns = reader.read<std::uint64_t>();
     collection.capture_end_ns = reader.read<std::uint64_t>();
 
+    if (reader.remaining_bytes() == 0U) {
+        return collection;
+    }
+
+    const auto trace_time_count = reader.read<std::uint32_t>();
+    if (trace_time_count != collection.traces.size()) {
+        throw std::runtime_error("Per-trace capture window count does not match trace count");
+    }
+    for (auto& trace : collection.traces) {
+        trace.capture_start_ns = reader.read<std::uint64_t>();
+        trace.capture_end_ns = reader.read<std::uint64_t>();
+    }
+
     return collection;
 }