diff --git a/infra/base-images/base-builder/indexer/dwarf_info_diff.py b/infra/base-images/base-builder/indexer/dwarf_info_diff.py
deleted file mode 100644
index 8e3e492f7cfb..000000000000
--- a/infra/base-images/base-builder/indexer/dwarf_info_diff.py
+++ /dev/null
@@ -1,78 +0,0 @@
-#!/usr/bin/env python3
-# Copyright 2026 Google LLC.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""Diffs compile commands generated via DWARF info and compilation databases."""
-
-import collections
-from collections.abc import Sequence
-import json
-import pathlib
-from absl import app
-from absl import flags
-from absl import logging
-import dwarf_info
-
-_BINARY_PATH = flags.DEFINE_string(
-    "binary_path", None, "Path to the binary file.", required=True
-)
-
-_COMPILE_COMMANDS_PATH = flags.DEFINE_string(
-    "compile_commands_path",
-    None,
-    "Path to the compile commands file.",
-    required=True,
-)
-
-
-def main(argv: Sequence[str]) -> None:
-  if len(argv) > 1:
-    raise app.UsageError("Too many command-line arguments.")
-
-  binary_path = pathlib.Path(_BINARY_PATH.value)
-  compilation_units = dwarf_info.get_all_compilation_units(binary_path)
-  logging.info("Found %d compilation units.", len(compilation_units))
-
-  # Question 1: Do we have repeated CU names in the binary?
-  cu_files = collections.Counter([cu.name for cu in compilation_units])
-  logging.info("Most Common CU names: %s", cu_files.most_common(1))
-
-  libs = binary_path.parent / "lib"
-  for lib in libs.iterdir():
-    new_cus = dwarf_info.get_all_compilation_units(lib)
-    logging.info("Found %d compilation units in %s", len(new_cus), lib)
-    compilation_units.extend(new_cus)
-
-  with open(_COMPILE_COMMANDS_PATH.value, "r") as f:
-    compile_commands = json.load(f)
-
-  # Question 2: Do we have repeated files in the compile commands?
-  cc_files = collections.Counter([cc["file"] for cc in compile_commands])
-  logging.info("Most Common commands files: %s", cc_files.most_common(1))
-
-  cc_files = set(cc_files)
-  cu_files = set(cu_files)
-
-  for file in cc_files - cu_files:
-    logging.info("File not found in CU: %s", file)
-
-  for file in cu_files - cc_files:
-    logging.info("File not found in CC: %s", file)
-
-  for file in cu_files.intersection(cc_files):
-    logging.info("File found in both: %s", file)
-
-
-if __name__ == "__main__":
-  app.run(main)
diff --git a/projects/s2geometry/build.sh b/projects/s2geometry/build.sh
index 2d8f6efa251a..cfdc54f15961 100755
--- a/projects/s2geometry/build.sh
+++ b/projects/s2geometry/build.sh
@@ -18,7 +18,13 @@
 cp $SRC/s2_fuzzer.cc $SRC/s2geometry/src/
 
 cd $SRC/
-git clone --depth=1 --branch 20260107.1 https://github.com/abseil/abseil-cpp
+# Keep this tag in sync with the abseil version s2geometry itself pins in its
+# CMakeLists.txt FETCH_ABSEIL block, which is what upstream CI builds against.
+# s2geometry now includes "absl/base/throw_delegate.h" (via
+# src/s2/util/gtl/compact_array.h), a header that only exists from abseil
+# 20260526.0 onwards -- with the older 20260107.1 pin every s2 translation unit
+# failed with "'absl/base/throw_delegate.h' file not found".
+git clone --depth=1 --branch 20260526.0 https://github.com/abseil/abseil-cpp
 cd abseil-cpp
 mkdir build && cd build
 cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON ../  && make && make install
diff --git a/projects/tinyusb/build.sh b/projects/tinyusb/build.sh
index 3bc62310fd17..3f72f1f62e5e 100755
--- a/projects/tinyusb/build.sh
+++ b/projects/tinyusb/build.sh
@@ -26,12 +26,49 @@ for f in test/fuzz/device/*/Makefile; do
   sed -i '/^[[:space:]]\+src[[:space:]]/s|src|$(abspath src)|' "$f"
 done
 
+# test/fuzz/make.mk bakes a fixed instrumentation choice into CFLAGS:
+#   COVERAGE_FLAGS  ?= -fsanitize-coverage=trace-pc-guard
+#   SANITIZER_FLAGS ?= -fsanitize=fuzzer -fsanitize=address
+# Those are the right defaults for a developer running the harnesses by hand,
+# but under OSS-Fuzz the engine and the sanitizer are chosen for us and are
+# already present in $CFLAGS/$LIB_FUZZING_ENGINE. Both are "?=", so clearing
+# them in the environment hands that choice back to OSS-Fuzz and stops, for
+# example, an msan build from also being asked for -fsanitize=address.
+export COVERAGE_FLAGS=""
+export SANITIZER_FLAGS=""
+
 fuzz_harness=$(ls -d test/fuzz/device/*/)
 for h in $fuzz_harness
 do
+  name=$(basename $h)
   make -C $h get-deps
-  make -C $h all
-  cp $h/_build/$(basename $h) $OUT/
+
+  if [ "$name" = "net_ncm" ]; then
+    # net_ncm is the one harness that does not include the shared
+    # make.mk/rules.mk. It is a standalone single-file harness whose Makefile
+    # sets its own flags outright:
+    #   CFLAGS += $(addprefix -I,$(INC)) -g -O1 -fsanitize=address
+    #   FUZZ_FLAGS := -fsanitize=fuzzer
+    # so it never consults $LIB_FUZZING_ENGINE and linked libFuzzer's main() no
+    # matter which engine was requested. Under centipede the resulting binary
+    # cannot dump a PC table, so check_build reported net_ncm as a broken target
+    # ("Could not get PCTable") and failed the whole project; the hardcoded
+    # -fsanitize=address would likewise collide with an msan build.
+    #
+    # Override both on the command line, which takes precedence over the "+="
+    # and ":=" in the Makefile, and re-supply the two include paths that the
+    # overridden CFLAGS line would otherwise have contributed ($(TOP)/src and
+    # the harness directory, which holds tusb_config.h). -lc++ is needed because
+    # this harness links with $CC rather than $CXX while the engine archive is
+    # C++.
+    make -C $h all \
+      CFLAGS="$CFLAGS -I$SRC/tinyusb/src -I." \
+      FUZZ_FLAGS="$LIB_FUZZING_ENGINE -lc++"
+  else
+    make -C $h all
+  fi
+
+  cp $h/_build/$name $OUT/
   corpus=$h/$(basename $h)_seed_corpus.zip
   if test -f $corpus; then
     cp $corpus $OUT/