Merge pull request #924 from 0xASTRA:fix/weights-readallbf16-missing-blob-size-assert

PiperOrigin-RevId: 925467040

Author: copybara-github

gemma/weights.cc

@@ -593,6 +593,10 @@ static void ReadAllToBF16(const std::vector<TensorToRead>& tensors,
                 GCPP_ZONE(ctx, thread, Zones::kStartupWeightsReadAllToBF16);
                 const TensorToRead& tensor = tensors[task];
                 MatPtr& mat = *tensor.mat;
+                // Validate blob size matches allocated buffer before any read.
+                // MapAll (line ~557) and MakeBatches (line ~645) both assert this;
+                // this path was the only one missing the check.
+                HWY_ASSERT_M(tensor.range.bytes == mat.PackedBytes(), mat.Name());
 
                 if (tensor.keep_type) {
                   HWY_ASSERT(reader.file().Read(