fix(udpscope): make the time-order test actually exercise the swap, guard the font copy

The ramp data in EmitsPointsInTimeOrder never produced a bucket whose maximum
preceded its minimum, so an implementation ordering the emitted pair by value
instead of by time would have passed. Replaced with an explicit two-bucket case
whose second bucket reverses the order.

file(COPY) is a hard configure error on a missing source, so a checkout without
the sibling StreamHub resources failed to configure despite the ASCII-icon
fallback the block above had just selected.

Plan amended to match on both points.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Client/udpscope/CMakeLists.txt

@@ -72,7 +72,11 @@ else()
     message(WARNING "Bundled Font Awesome missing — using ASCII icon fallbacks")
 endif()
 
-file(COPY ${FONT_DIR} DESTINATION ${CMAKE_BINARY_DIR}/resources)
+# Guarded: file(COPY) is a hard configure error on a missing source, which
+# would defeat the fallback the block above just chose.
+if(EXISTS ${FONT_DIR})
+    file(COPY ${FONT_DIR} DESTINATION ${CMAKE_BINARY_DIR}/resources)
+endif()
 
 # ── Core library: everything except main.cpp, so tests can link it ────────────
 set(CORE_SOURCES

Client/udpscope/tests/DecimateTest.cpp

@@ -49,6 +49,23 @@ TEST(MinMaxDecimate, PreservesTheExtremesOfEveryBucket) {
 // A ring whose timestamps are not monotonic breaks any later binary search by
 // time, so the pair emitted per bucket must be ordered by time, not by value.
 TEST(MinMaxDecimate, EmitsPointsInTimeOrder) {
+    // Two buckets of four. In the first the minimum comes before the maximum,
+    // in the second the order is reversed. An implementation that emitted
+    // (min, max) by value rather than by time passes on bucket 0 and fails on
+    // bucket 1, so this data exercises the swap that a monotonically growing
+    // ramp never triggers.
+    const double st[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+    const double sv[8] = {-5, 0, 0, 9, 9, 0, 0, -5};
+    Series pair;
+    MinMaxDecimate(st, sv, 8, 4, pair);
+    ASSERT_EQ(pair.size(), 4u);
+    const double wantT[4] = {0, 3, 4, 7};
+    const double wantV[4] = {-5, 9, 9, -5};
+    for (size_t i = 0; i < 4; i++) {
+        EXPECT_EQ(pair.t[i], wantT[i]) << "time at " << i;
+        EXPECT_EQ(pair.v[i], wantV[i]) << "value at " << i;
+    }
+
     std::vector<double> t(400), v(400);
     for (size_t i = 0; i < t.size(); i++) {
         t[i] = static_cast<double>(i);

docs/superpowers/plans/2026-08-27-udpscope.md

@@ -128,6 +128,23 @@ TEST(MinMaxDecimate, PreservesTheExtremesOfEveryBucket) {
 // A ring whose timestamps are not monotonic breaks any later binary search by
 // time, so the pair emitted per bucket must be ordered by time, not by value.
 TEST(MinMaxDecimate, EmitsPointsInTimeOrder) {
+    // Two buckets of four. In the first the minimum comes before the maximum,
+    // in the second the order is reversed. An implementation that emitted
+    // (min, max) by value rather than by time passes on bucket 0 and fails on
+    // bucket 1, so this data exercises the swap that a monotonically growing
+    // ramp never triggers.
+    const double st[8] = {0, 1, 2, 3, 4, 5, 6, 7};
+    const double sv[8] = {-5, 0, 0, 9, 9, 0, 0, -5};
+    Series pair;
+    MinMaxDecimate(st, sv, 8, 4, pair);
+    ASSERT_EQ(pair.size(), 4u);
+    const double wantT[4] = {0, 3, 4, 7};
+    const double wantV[4] = {-5, 9, 9, -5};
+    for (size_t i = 0; i < 4; i++) {
+        EXPECT_EQ(pair.t[i], wantT[i]) << "time at " << i;
+        EXPECT_EQ(pair.v[i], wantV[i]) << "value at " << i;
+    }
+
     std::vector<double> t(400), v(400);
     for (size_t i = 0; i < t.size(); i++) {
         t[i] = static_cast<double>(i);
@@ -362,7 +379,11 @@ else()
     message(WARNING "Bundled Font Awesome missing — using ASCII icon fallbacks")
 endif()
 
-file(COPY ${FONT_DIR} DESTINATION ${CMAKE_BINARY_DIR}/resources)
+# Guarded: file(COPY) is a hard configure error on a missing source, which
+# would defeat the fallback the block above just chose.
+if(EXISTS ${FONT_DIR})
+    file(COPY ${FONT_DIR} DESTINATION ${CMAKE_BINARY_DIR}/resources)
+endif()
 
 # ── Core library: everything except main.cpp, so tests can link it ────────────
 set(CORE_SOURCES