fix: close Θ-W7-T1 round-2 leftovers — NaN guard placement, comment attribution, CLAUDE.md export

Moves the NaN/Inf finiteness check to addSegment where the UB-causing cast actually happens, makes strokeBounds reject an interior non-finite point instead of swallowing it, corrects a LICE_GetPixel misattribution, and documents rasterRowOffset.

tests/test_stroke_aa.cpp

@@ -289,6 +289,31 @@ static void testCoverageOutsideTheValidSpanReadsZero() {
     CHECK(c.coverageAt(1000, 1000) == 0.0f);
 }
 
+// --- non-finite input rejection ------------------------------------------------
+
+static void testInteriorNonFiniteCoordinateRejectsTheWholeStroke() {
+    // Only pts[0] going non-finite used to propagate through strokeBounds's min/max reduction:
+    // std::min/max against NaN silently returns the OTHER, finite, operand, so a NaN anywhere
+    // else in the polyline vanished from the reduction instead of rejecting it. pts[1] here is
+    // the case that check missed.
+    const StrokePoint pts[3] = {{10.0f, 10.0f}, {NAN, 50.0f}, {90.0f, 10.0f}};
+    CHECK(strokeBounds(pts, 3, 1.5f, kBig).empty());
+
+    StrokeCanvas c;
+    strokePolyline(c, pts, 3, 1.5f, kBig);
+    CHECK(c.bounds().empty());
+}
+
+static void testAddSegmentRejectsNonFiniteInputsDirectly() {
+    // addSegment casts a pieces-count derived from len2 to int; a NaN/Inf endpoint must be
+    // caught before that cast, not one call layer down in addPiece where it's already too late.
+    StrokeCanvas c;
+    c.reset(kBig);
+    c.addSegment(10.0f, 10.0f, NAN, 50.0f, 1.5f);
+    c.addSegment(10.0f, 10.0f, INFINITY, 50.0f, 1.5f);
+    CHECK(peakCoverage(c) == 0.0f);
+}
+
 // --- raster row addressing ----------------------------------------------------
 
 static void testRasterRowOffsetMatchesUnflippedAndFlippedLayouts() {
@@ -296,8 +321,8 @@ static void testRasterRowOffsetMatchesUnflippedAndFlippedLayouts() {
     CHECK(rasterRowOffset(0, 100, 240, false) == 0u);
     CHECK(rasterRowOffset(5, 100, 240, false) == 5u * 240u);
     CHECK(rasterRowOffset(99, 100, 240, false) == 99u * 240u);
-    // Flipped (bottom-up DIBs): row y is (height-1-y)*rowSpan — LICE_SysBitmap's own pixel
-    // accessor, `(h-1-y)*rowspan + x` (lice.cpp:2262).
+    // Flipped (bottom-up DIBs): row y is (height-1-y)*rowSpan — matches the free function
+    // LICE_GetPixel's own row math, `(h-1-y)*rowspan + x` (lice.cpp:2262).
     CHECK(rasterRowOffset(0, 100, 240, true) == 99u * 240u);
     CHECK(rasterRowOffset(99, 100, 240, true) == 0u);
     CHECK(rasterRowOffset(40, 100, 240, true) == 59u * 240u);
@@ -441,6 +466,8 @@ int main() {
     testBoundsClipToTheClipRectAndCoverTheReach();
     testStrokeEntirelyOutsideTheClipDrawsNothing();
     testCoverageOutsideTheValidSpanReadsZero();
+    testInteriorNonFiniteCoordinateRejectsTheWholeStroke();
+    testAddSegmentRejectsNonFiniteInputsDirectly();
     testRasterRowOffsetMatchesUnflippedAndFlippedLayouts();
     testSubdivisionDoesNotChangeTheRenderedStroke();
     testArcPointsLieOnTheCircleAndRespectTheFlatness();