From f53c6ae5b347bf68ca05d69937d5936ee420f3d0 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 00:31:18 +0700
Subject: [PATCH 01/18] ci: collect Windows code-size evidence

---
 .github/workflows/code_size_windows.yml | 76 +++++++++++++++++++++++++
 tools/ci_select.py                      |  2 +-
 2 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 .github/workflows/code_size_windows.yml

diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
new file mode 100644
index 0000000000..957ff82fbe
--- /dev/null
+++ b/.github/workflows/code_size_windows.yml
@@ -0,0 +1,76 @@
+name: Code size on Windows
+
+on:
+  workflow_dispatch:
+  push:
+    branches: [ claude/code-size-windows ]
+
+permissions:
+  contents: read
+
+jobs:
+  evidence:
+    runs-on: windows-latest
+    steps:
+      - name: Checkout TinyUSB
+        uses: actions/checkout@v6
+
+      - name: Setup Toolchain
+        uses: ./.github/actions/setup_toolchain
+        with:
+          toolchain: 'arm-gcc-windows-latest'
+
+      - name: Get Dependencies
+        uses: ./.github/actions/get_deps
+        with:
+          arg: '-b stm32f407disco'
+
+      - name: Install membrowse
+        run: 'python -m pip install --only-binary :all: membrowse==1.2.12'
+        shell: bash
+
+      - name: Build one example as code_size.py does
+        run: |
+          cmake -B evidence -G Ninja -DBOARD=stm32f407disco -DCMAKE_BUILD_TYPE=MinSizeRel examples
+          ninja -C evidence cdc_msc
+        shell: bash
+
+      - name: Dump link command and membrowse source paths
+        run: |
+          mkdir -p evidence-out
+          find evidence -name 'cdc_msc.elf' | tee evidence-out/elf.txt
+          ninja -C evidence -t commands -s device/cdc_msc/cdc_msc.elf > evidence-out/link-fwd.txt 2>&1 || true
+          ninja -C evidence -t commands -s 'device\cdc_msc\cdc_msc.elf' > evidence-out/link-back.txt 2>&1 || true
+          tail -c 4000 evidence-out/link-fwd.txt
+          python -X utf8 - <<'EOF' > evidence-out/membrowse-paths.txt 2>&1 || true
+          import json, os, subprocess, sys
+          sys.path.insert(0, 'tools')
+          from membrowse_cli import extract_ld_scripts, extract_defsyms, link_command, report_inputs
+          elf = os.path.join('evidence', 'device', 'cdc_msc', 'cdc_msc.elf')
+          commands = link_command('ninja', 'evidence', elf)
+          print('ld scripts:', extract_ld_scripts(commands))
+          print('defsyms:', extract_defsyms(commands))
+          cmd = ['membrowse', 'report'] + report_inputs(elf, extract_ld_scripts(commands), extract_defsyms(commands)) + ['--json', '--all-symbols']
+          print('cmd:', cmd)
+          r = subprocess.run(cmd, capture_output=True, text=True, encoding='utf-8', errors='replace')
+          print('rc', r.returncode, r.stderr[-2000:])
+          if r.returncode == 0:
+              data = json.loads(r.stdout)
+              files = sorted({f"{s.get('object_file')} | {s.get('source_file')}" for s in data.get('symbols', [])})
+              print('source files:', len(files))
+              print('\n'.join(files[:80]))
+          EOF
+          cat evidence-out/membrowse-paths.txt
+        shell: bash
+
+      - name: Probe the unchanged CLI (expected to fail)
+        continue-on-error: true
+        run: python -X utf8 tools/code_size.py report -b stm32f407disco -e device/cdc_msc 2>&1 | tee evidence-out/probe.txt
+        shell: bash
+
+      - name: Upload evidence
+        if: always()
+        uses: actions/upload-artifact@v7
+        with:
+          name: code-size-windows-evidence
+          path: evidence-out/
diff --git a/tools/ci_select.py b/tools/ci_select.py
index e7e989e27a..e140663629 100755
--- a/tools/ci_select.py
+++ b/tools/ci_select.py
@@ -122,7 +122,7 @@ def _read(path: str) -> str:
     # .github, minus the build machinery named in _FULL_RE and _CI_BOARDS_RE
     r'\.github/(FUNDING\.yml$|labeler\.yml$|'
     r'ISSUE_TEMPLATE/|scripts/code_size_ci\.py$|'
-    r'workflows/(cifuzz|claude|claude-code-review|labeler|'
+    r'workflows/(cifuzz|claude|claude-code-review|code_size_windows|labeler|'
     r'pr_comment|pre-commit|static_analysis|trigger)\.yml$)|'
     # tools/ scripts no build invokes (tools/build*.py and local tooling are handled separately)
     r'tools/(check_example_pids|file2carray|iar_gen|mksunxi|pcapng_to_corpus)\.py$|'

From 207be943a5af21d8e8e201b608368bbabdddce8f Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 00:43:46 +0700
Subject: [PATCH 02/18] code_size: run report and diff on Windows

---
 .github/workflows/code_size_windows.yml | 93 +++++++++++++------------
 test/hil/test/test_code_size.py         | 37 ++++++++++
 test/hil/test/test_membrowse_cli.py     |  9 +++
 tools/code_size.py                      | 39 ++++++++---
 tools/membrowse_cli.py                  |  3 +
 5 files changed, 130 insertions(+), 51 deletions(-)

diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
index 957ff82fbe..e62a67f14e 100644
--- a/.github/workflows/code_size_windows.yml
+++ b/.github/workflows/code_size_windows.yml
@@ -2,18 +2,48 @@ name: Code size on Windows
 
 on:
   workflow_dispatch:
+  pull_request:
+    paths: &code_size_paths
+      - 'tools/code_size.py'
+      - 'tools/membrowse_cli.py'
+      - 'tools/build_utils.py'
+      - 'test/hil/test/test_code_size*.py'
+      - 'test/hil/test/test_membrowse_cli.py'
+      - '.github/scripts/code_size_ci.py'
+      - '.github/workflows/code_size_windows.yml'
   push:
-    branches: [ claude/code-size-windows ]
+    branches: [ master, claude/code-size-windows ]
+    paths: *code_size_paths
 
 permissions:
   contents: read
+  actions: read
+
+env:
+  PYTHONUTF8: '1'
 
 jobs:
-  evidence:
+  unit-test:
     runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v6
+      - run: python -m pip install pytest
+      - run: python -m pytest -q test/hil/test/test_code_size.py test/hil/test/test_code_size_ci.py test/hil/test/test_membrowse_cli.py
+
+  smoke:
+    runs-on: windows-latest
+    env:
+      BOARD: stm32f407disco
+      EXAMPLE: device/cdc_msc
+      GH_TOKEN: ${{ github.token }}
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: Checkout TinyUSB
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
 
       - name: Setup Toolchain
         uses: ./.github/actions/setup_toolchain
@@ -27,50 +57,27 @@ jobs:
 
       - name: Install membrowse
         run: 'python -m pip install --only-binary :all: membrowse==1.2.12'
-        shell: bash
 
-      - name: Build one example as code_size.py does
+      - name: Report
         run: |
-          cmake -B evidence -G Ninja -DBOARD=stm32f407disco -DCMAKE_BUILD_TYPE=MinSizeRel examples
-          ninja -C evidence cdc_msc
-        shell: bash
+          python tools/code_size.py report -b $BOARD -e $EXAMPLE --json
+          python - <<'EOF'
+          import json
+          data = json.load(open('cmake-code-size/stm32f407disco/report_device_cdc_msc.json'))
+          files = {f for e in data['elfs'] for f in e['sizes']['files']}
+          print(data['status'], sorted(files))
+          assert data['status'] == 'complete' and any(f.endswith('usbd.c') for f in files), 'no TinyUSB files'
+          EOF
 
-      - name: Dump link command and membrowse source paths
+      - name: Diff against a local base
         run: |
-          mkdir -p evidence-out
-          find evidence -name 'cdc_msc.elf' | tee evidence-out/elf.txt
-          ninja -C evidence -t commands -s device/cdc_msc/cdc_msc.elf > evidence-out/link-fwd.txt 2>&1 || true
-          ninja -C evidence -t commands -s 'device\cdc_msc\cdc_msc.elf' > evidence-out/link-back.txt 2>&1 || true
-          tail -c 4000 evidence-out/link-fwd.txt
-          python -X utf8 - <<'EOF' > evidence-out/membrowse-paths.txt 2>&1 || true
-          import json, os, subprocess, sys
-          sys.path.insert(0, 'tools')
-          from membrowse_cli import extract_ld_scripts, extract_defsyms, link_command, report_inputs
-          elf = os.path.join('evidence', 'device', 'cdc_msc', 'cdc_msc.elf')
-          commands = link_command('ninja', 'evidence', elf)
-          print('ld scripts:', extract_ld_scripts(commands))
-          print('defsyms:', extract_defsyms(commands))
-          cmd = ['membrowse', 'report'] + report_inputs(elf, extract_ld_scripts(commands), extract_defsyms(commands)) + ['--json', '--all-symbols']
-          print('cmd:', cmd)
-          r = subprocess.run(cmd, capture_output=True, text=True, encoding='utf-8', errors='replace')
-          print('rc', r.returncode, r.stderr[-2000:])
-          if r.returncode == 0:
-              data = json.loads(r.stdout)
-              files = sorted({f"{s.get('object_file')} | {s.get('source_file')}" for s in data.get('symbols', [])})
-              print('source files:', len(files))
-              print('\n'.join(files[:80]))
+          python tools/code_size.py diff -b $BOARD -e $EXAMPLE --base-source local --base-branch HEAD --json
+          python - <<'EOF'
+          import json
+          data = json.load(open('cmake-code-size/stm32f407disco/diff_device_cdc_msc.json'))
+          assert data['status'] == 'complete' and data['pairs'], data['status']
+          assert all(p['base']['files'] == p['current']['files'] for p in data['pairs']), 'HEAD vs HEAD changed'
           EOF
-          cat evidence-out/membrowse-paths.txt
-        shell: bash
 
-      - name: Probe the unchanged CLI (expected to fail)
-        continue-on-error: true
-        run: python -X utf8 tools/code_size.py report -b stm32f407disco -e device/cdc_msc 2>&1 | tee evidence-out/probe.txt
-        shell: bash
-
-      - name: Upload evidence
-        if: always()
-        uses: actions/upload-artifact@v7
-        with:
-          name: code-size-windows-evidence
-          path: evidence-out/
+      - name: Diff against CI snapshots
+        run: python tools/code_size.py diff -b $BOARD -e $EXAMPLE --base-source ci --base-branch origin/master
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 83b1ea05b2..ec326c0482 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1068,6 +1068,7 @@ def test_without_idf_or_its_image_the_espressif_build_fails_saying_how_to_get_on
             self.assertEqual(runs, [])
             self.assertIn('esp needs ESP-IDF: source $IDF_PATH/export.sh', error)
 
+    @mock.patch.object(sd, 'WINDOWS', new=False)
     def test_without_idf_report_and_diff_refuse_an_espressif_board_before_building(self):
         pinned = ['stm32f407disco', 'espressif_s3_devkitm']
         for argv in (['report', '-b', pinned[0], '-b', pinned[1]], ['diff', '-b', pinned[0], '-b', pinned[1]],
@@ -1236,6 +1237,7 @@ def test_a_real_checkout_has_a_hash(self):
         self.assertRegex(sd.short_hash(sd.TINYUSB_ROOT), r'^[0-9a-f]{7,}(-dirty)?$')
 
 
+@unittest.skipIf(os.name == 'nt', 'the Windows filter drops the drive')
 class SymlinkedCheckout(unittest.TestCase):
     def test_the_root_matches_its_own_filter_through_a_symlink(self):
         with tempfile.TemporaryDirectory() as tmp:
@@ -1248,6 +1250,41 @@ def test_the_root_matches_its_own_filter_through_a_symlink(self):
         self.assertEqual(out, 'True\n')
 
 
+@mock.patch.object(sd, 'WINDOWS', new=True)
+class WindowsHost(unittest.TestCase):
+    def test_a_backslash_object_path_matches_the_forward_slash_filter(self):
+        for f in ('/a/tinyusb/src/', '\\a\\tinyusb\\src\\'):
+            self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\a\tinyusb\src\device\usbd.c.obj', [f]), 'device/usbd.c')
+
+    def test_espressif_boards_are_refused(self):
+        self.assertRegex(sd.esp_without_idf(['espressif_s3_devkitc', 'stm32f407disco']),
+                         r'^espressif_s3_devkitc need ESP-IDF, .* not support on Windows')
+        self.assertIsNone(sd.esp_without_idf(['stm32f407disco']))
+
+    def test_a_timeout_kills_the_command_tree(self):
+        with mock.patch('subprocess.run') as taskkill:
+            ret = sd.run([sys.executable, '-c', 'import time; time.sleep(30)'], timeout=0.5)
+        self.assertEqual(ret.returncode, 124)
+        argv = taskkill.call_args.args[0]
+        self.assertEqual(argv[:2] + argv[3:], ['taskkill', '/PID', '/T', '/F'])
+
+    def test_a_symlink_without_the_privilege_names_developer_mode(self):
+        denied = OSError(22, 'A required privilege is not held by the client')
+        denied.winerror = 1314
+        with tempfile.TemporaryDirectory() as main, tempfile.TemporaryDirectory() as wt:
+            os.makedirs(os.path.join(main, 'lib/lwip'))
+            os.makedirs(os.path.join(wt, 'tools'))
+            with open(os.path.join(wt, 'tools', 'get_deps.py'), 'w') as f:
+                f.write("deps_all = {'lib/lwip': []}\n")
+            with mock.patch('os.symlink', side_effect=denied), \
+                    self.assertRaisesRegex(SystemExit, 'Developer Mode, or use --base-source ci'):
+                sd.symlink_deps(main, wt)
+
+    def test_a_path_on_another_drive_is_shown_absolute(self):
+        with mock.patch('os.path.relpath', side_effect=ValueError('path is on mount C:, start on mount D:')):
+            self.assertEqual(sd._shown('C:/x/report.md'), 'C:/x/report.md')
+
+
 # main() tests stub the builds and sizing, so need no engine tool
 @mock.patch.object(sd, 'engine_missing', new=lambda _engine: False)
 class MainFailure(unittest.TestCase):
diff --git a/test/hil/test/test_membrowse_cli.py b/test/hil/test/test_membrowse_cli.py
index a75271647a..ba4e002077 100644
--- a/test/hil/test/test_membrowse_cli.py
+++ b/test/hil/test/test_membrowse_cli.py
@@ -36,6 +36,15 @@ def test_ld_script_extraction_handles_drive_letters_and_spaces(self):
         self.assertEqual(cli.extract_ld_scripts(text),
                          ['C:/work/tinyusb/board.ld', '/work/a b/board.ld'])
 
+    def test_ld_script_extraction_unwraps_the_windows_ninja_cmd_wrapper(self):
+        # shortened from a windows-latest `ninja -t commands` link line
+        text = (r'C:\Windows\system32\cmd.exe /C "cd . && C:\gcc\bin\arm-none-eabi-gcc.exe -Os '
+                r'-Wl,-Map=D:/a/out/cdc_msc.elf.map -Wl,--script=D:/a/bsp/STM32F407VGTx_FLASH.ld '
+                r'main.c.obj -o device\cdc_msc\cdc_msc.elf  lib/libboard.a && C:\Windows\system32\cmd.exe /C '
+                r'"cd /D D:\a\out && C:\gcc\bin\arm-none-eabi-objcopy.exe -Obinary D:/a/out/cdc_msc.elf '
+                r'D:/a/out/cdc_msc.bin""' '\n')
+        self.assertEqual(cli.extract_ld_scripts(text), ['D:/a/bsp/STM32F407VGTx_FLASH.ld'])
+
     def test_defsym_extraction_both_separators(self):
         text = 'cc -Wl,--defsym=FOO=0x10 -Wl,--defsym,BAR=1 -o out.elf\n'
         self.assertEqual(cli.DEFSYM_RE.findall(text), ['FOO=0x10', 'BAR=1'])
diff --git a/tools/code_size.py b/tools/code_size.py
index a15013add5..adaed78e0a 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -60,9 +60,11 @@
 # resolved like tinyusb_src_filter(), so a symlinked checkout still matches its filter
 TINYUSB_ROOT = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
 CODE_SIZE_DIR = os.path.join(TINYUSB_ROOT, 'cmake-code-size')
+WINDOWS = os.name == 'nt'
 # a master run's snapshots are the same for every checkout; XDG ignores a relative XDG_CACHE_HOME
-_xdg_cache = os.environ.get('XDG_CACHE_HOME', '')
-BASELINE_CACHE_DIR = os.path.join(_xdg_cache if os.path.isabs(_xdg_cache) else os.path.expanduser('~/.cache'),
+_cache_home = os.environ.get('LOCALAPPDATA' if WINDOWS else 'XDG_CACHE_HOME', '')
+BASELINE_CACHE_DIR = os.path.join(_cache_home if os.path.isabs(_cache_home) else
+                                  os.path.expanduser('~/AppData/Local' if WINDOWS else '~/.cache'),
                                   'tinyusb', 'code-size-baseline')
 CI_PINNED_BOARDS = os.path.join(TINYUSB_ROOT, '.github', 'ci-pinned-boards.json')
 # a diff's side names when git cannot give their commit hashes
@@ -131,6 +133,9 @@ def _classify_region(name):
 def _relative_key(src, filters):
     """Source path relative to the first matching filter, object suffix stripped,
     or None when no filter matches."""
+    if WINDOWS:
+        src = src.replace('\\', '/')
+        filters = [f.replace('\\', '/') for f in filters]
     for f in filters:
         idx = src.find(f)
         if idx < 0:
@@ -836,7 +841,9 @@ def tinyusb_src_filter(checkout_dir):
     in `checkout_dir`. The substring is the absolute path to the checkout's `src/`
     dir — collision-free with vendored deps (pico-sdk, lwip, FreeRTOS, etc.) which
     live at unrelated paths."""
-    return os.path.realpath(os.path.join(checkout_dir, 'src')) + os.sep
+    path = os.path.realpath(os.path.join(checkout_dir, 'src')) + os.sep
+    # Windows: CMake names an out-of-tree object D_/a/.../src/x.c.obj and DWARF D:/a/...: match past the drive
+    return os.path.splitdrive(path)[1].replace('\\', '/') if WINDOWS else path
 
 
 verbose = False
@@ -861,6 +868,10 @@ def run(cmd, timeout=None):
         try:
             out, err = proc.communicate(timeout=timeout)
         except BaseException as stopped:
+            if WINDOWS:  # terminate() and kill() stop only the command, not ninja's compilers
+                with contextlib.suppress(OSError, subprocess.SubprocessError):
+                    subprocess.run(['taskkill', '/PID', str(proc.pid), '/T', '/F'],
+                                   capture_output=True, timeout=TERMINATE_GRACE)
             # SIGTERM lets ninja stop its jobs, which it runs in process groups of their own;
             # a descendant can outlive the SIGKILL holding the pipes open, so stop reading then
             for stop, wait in ((proc.terminate, TERMINATE_GRACE), (proc.kill, KILL_DRAIN)):
@@ -880,8 +891,9 @@ def run(cmd, timeout=None):
 def exit_on_termination():
     """Exit on a SIGTERM or SIGHUP sent to this process alone as on Ctrl-C: through run()'s
     stop of its command and main()'s worktree removal, instead of orphaning the build."""
-    for signum in (signal.SIGTERM, signal.SIGHUP):
-        signal.signal(signum, lambda sig, _frame: sys.exit(128 + sig))
+    for name in ('SIGTERM', 'SIGHUP'):  # Windows has no SIGHUP
+        if hasattr(signal, name):
+            signal.signal(getattr(signal, name), lambda sig, _frame: sys.exit(128 + sig))
 
 
 def symlink_deps(main_root, worktree_dir):
@@ -894,7 +906,13 @@ def symlink_deps(main_root, worktree_dir):
         dst = os.path.join(worktree_dir, rel)
         if os.path.isdir(src) and not os.path.lexists(dst):
             os.makedirs(os.path.dirname(dst), exist_ok=True)
-            os.symlink(src, dst)
+            try:
+                os.symlink(src, dst, target_is_directory=True)
+            except OSError as e:
+                if getattr(e, 'winerror', None) == 1314:  # ERROR_PRIVILEGE_NOT_HELD
+                    sys.exit(f'Error: cannot symlink {rel} into the base worktree: enable Windows Developer '
+                             'Mode, or use --base-source ci when CI stored a baseline')
+                raise
 
 
 def short_hash(checkout):
@@ -991,6 +1009,8 @@ def _idf_image():
 def esp_without_idf(boards):
     """The error for espressif `boards` no exported ESP-IDF or CI's image can build, else None."""
     esp = [b for b in boards if is_espressif(b)]
+    if esp and WINDOWS:
+        return f'{", ".join(esp)} need ESP-IDF, which code_size.py does not support on Windows'
     if esp and not (shutil.which('idf.py') or _idf_image()):
         return f'{", ".join(esp)} need {ESP_IDF_MISSING}'
     return None
@@ -1128,7 +1148,7 @@ def report(elf):
                            f'or pick another --engine')]
     sizes, errors = {}, []
     for elf, (elf_sizes, error) in zip(elfs, results):
-        rel = os.path.relpath(elf, build_dir)
+        rel = os.path.relpath(elf, build_dir).replace(os.sep, '/')  # one elf id on every host
         sizes[rel] = elf_sizes
         if error:
             errors.append((rel, error))
@@ -1178,7 +1198,10 @@ def print_result(lines, prefix='', tables=()):
 
 def _shown(path):
     """`path` relative to the working directory when under it."""
-    rel = os.path.relpath(path)
+    try:
+        rel = os.path.relpath(path)
+    except ValueError:  # on another Windows drive
+        return path
     return path if rel.startswith('..') else rel
 
 
diff --git a/tools/membrowse_cli.py b/tools/membrowse_cli.py
index 12b06f7aee..053beb4fed 100644
--- a/tools/membrowse_cli.py
+++ b/tools/membrowse_cli.py
@@ -42,6 +42,9 @@ def extract_ld_scripts(commands_text):
     for line in commands_text.splitlines():
         try:
             args = shlex.split(line)
+            # Windows ninja links through `cmd.exe /C "cd . && <link command>"`
+            if len(args) >= 3 and args[0].lower().endswith('cmd.exe') and args[1].lower() == '/c':
+                args = shlex.split(args[2])
         except ValueError:
             continue
         for i, arg in enumerate(args):

From faccbaec4b0060d07ec449557dcfa36c43b5453a Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 00:51:58 +0700
Subject: [PATCH 03/18] code_size: shorten Windows compiler error paths, skip
 POSIX-only tests there

---
 .github/workflows/code_size_windows.yml |  2 +-
 test/hil/test/test_code_size.py         | 15 +++++++++++++--
 test/hil/test/test_membrowse_cli.py     | 10 ++++++++++
 tools/code_size.py                      |  5 ++++-
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
index e62a67f14e..b80fd3c03b 100644
--- a/.github/workflows/code_size_windows.yml
+++ b/.github/workflows/code_size_windows.yml
@@ -27,7 +27,7 @@ jobs:
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v6
-      - run: python -m pip install pytest
+      - run: python -m pip install pytest pyyaml pyelftools
       - run: python -m pytest -q test/hil/test/test_code_size.py test/hil/test/test_code_size_ci.py test/hil/test/test_membrowse_cli.py
 
   smoke:
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index ec326c0482..1111951e29 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -27,6 +27,9 @@
 sys.path.insert(0, os.path.join(REPO, 'tools'))
 import code_size as sd  # noqa: E402
 
+posix_only = unittest.skipIf(os.name == 'nt', 'needs a POSIX shell and signals')
+no_esp_on_windows = unittest.skipIf(os.name == 'nt', 'code_size.py refuses ESP-IDF on Windows')
+
 
 def fake_report(symbols):
     return {'symbols': symbols}
@@ -66,6 +69,7 @@ def test_uses_the_elfs_link_and_runs_from_the_build_dir(self):
             self.assertEqual(cmd[cmd.index('--def') + 1], 'X=1')
             self.assertEqual(run.call_args.kwargs['cwd'], build)
 
+    @no_esp_on_windows
     def test_an_esp_idf_build_uses_its_generated_scripts(self):
         with tempfile.TemporaryDirectory() as build:
             open(os.path.join(build, 'build.ninja'), 'w').close()
@@ -636,7 +640,7 @@ def test_the_real_parser_reads_a_gnu_map(self):
 
 
 class DwarfSources(unittest.TestCase):
-    @unittest.skipUnless(shutil.which('gcc'), 'needs gcc to build an elf with DWARF')
+    @unittest.skipUnless(shutil.which('gcc') and os.name != 'nt', 'needs a gcc that builds an elf with DWARF')
     def test_compile_units_are_found_by_basename(self):
         with tempfile.TemporaryDirectory() as tmp:
             for rel, code in (('src/device/usbd.c', 'int usbd(void) { return 1; }\n'),
@@ -1037,6 +1041,7 @@ def run(cmd, timeout=None):
             error = sd.build_board(self._esp_src(tmp), os.path.join(tmp, 'b'), 'esp', example, 'build')
         return error, runs
 
+    @no_esp_on_windows
     def test_an_espressif_board_builds_each_examples_app_as_an_idf_project(self):
         with tempfile.TemporaryDirectory() as tmp:
             error, runs = self._build_esp(tmp)
@@ -1045,6 +1050,7 @@ def test_an_espressif_board_builds_each_examples_app_as_an_idf_project(self):
                                   '-B', os.path.join(tmp, 'b', 'device', 'a_freertos'), '-GNinja', '-DBOARD=esp',
                                   'app'], 600)])
 
+    @no_esp_on_windows
     def test_without_an_exported_idf_it_builds_in_cis_image_as_this_user(self):
         with tempfile.TemporaryDirectory() as tmp:
             error, runs = self._build_esp(tmp, which=('docker',))
@@ -1091,6 +1097,7 @@ def test_an_example_the_tree_does_not_build_for_espressif_fails_the_build(self):
                 error, runs = self._build_esp(tmp, example=example)
             self.assertEqual((error, runs), (f'esp builds no {example}', []))
 
+    @no_esp_on_windows
     def test_a_timed_out_or_interrupted_docker_build_removes_its_container(self):
         rm = ['docker', 'rm', '-f', f'tinyusb-code-size-{os.getpid()}']
         for which, rc, removed in ((('docker',), 124, True), (('docker',), 2, False), (('idf.py',), 124, False)):
@@ -1115,6 +1122,7 @@ def test_output_that_is_not_utf8_is_decoded_with_replacement(self):
                 self.assertEqual((ret.returncode, ret.stdout), (rc, 'w: \ufffd\n'))
                 self.assertTrue(ret.stderr.startswith('\ufffd'))
 
+    @posix_only
     def test_sigterm_to_the_script_alone_stops_its_command_and_runs_cleanup(self):
         """Popen's exit waits for the command, so the handler passes the signal on, and
         kills a command ignoring it after the grace."""
@@ -1158,6 +1166,7 @@ def test_a_command_ignoring_sigterm_is_killed_after_the_grace(self):
             ret = sd.run(['sh', '-c', "trap '' TERM; while :; do sleep 0.1; done"], timeout=1)
         self.assertEqual(ret.returncode, 124)
 
+    @posix_only
     def test_a_child_holding_the_pipes_after_the_kill_does_not_hang_it(self):
         start = time.monotonic()
         with mock.patch.object(sd, 'TERMINATE_GRACE', 0.5):
@@ -1168,6 +1177,7 @@ def test_a_child_holding_the_pipes_after_the_kill_does_not_hang_it(self):
         self.assertEqual(ret.returncode, 124)
         self.assertIn('Command timed out after 1s', ret.stderr)
 
+    @posix_only
     def test_a_child_holding_the_pipes_after_sigterm_does_not_hang_it(self):
         start = time.monotonic()
         with mock.patch.object(sd, 'TERMINATE_GRACE', 0.5), mock.patch.object(sd, 'KILL_DRAIN', 0.2):
@@ -1986,6 +1996,7 @@ def test_ci_adds_the_pinned_boards_after_the_named_ones_once_each(self):
                                             '"uncovered": []}')
             self.assertEqual(built, ['extra', 'b1', 'b2'])
 
+    @mock.patch.object(sd, 'WINDOWS', new=False)
     def test_ci_builds_pinned_espressif_boards_too(self):
         with tempfile.TemporaryDirectory() as tmp:
             built = self._boards_built(tmp, '{"boards": [{"board": "b1"}, '
@@ -2176,7 +2187,7 @@ def test_a_variant_reports_its_board_under_the_build_name(self):
                 self.assertEqual(json.load(f)['boards'], ['b1-DMA'])
             with open(os.path.join(out, 'code-size-b1-DMA.json')) as f:
                 self.assertEqual(json.load(f)['board'], 'b1-DMA')
-        self.assertEqual([os.path.relpath(p, build_root) for p in sized], ['cmake-build-b1-DMA/device/a/a.elf'])
+        self.assertEqual([os.path.relpath(p, build_root) for p in sized], [os.path.join('cmake-build-b1-DMA', 'device', 'a', 'a.elf')])
         # the board's own skip rules, with the leg's defines as build.py applied them
         boards.assert_called_once_with([], ['b1'], ['device/a'], ('MAX3421_HOST=1',))
         skip.assert_called_with('device/a', 'b1', ('MAX3421_HOST=1',))
diff --git a/test/hil/test/test_membrowse_cli.py b/test/hil/test/test_membrowse_cli.py
index ba4e002077..80216627ba 100644
--- a/test/hil/test/test_membrowse_cli.py
+++ b/test/hil/test/test_membrowse_cli.py
@@ -17,6 +17,10 @@
 import membrowse_cli as cli  # noqa: E402
 
 
+# the tests run executable #! stubs, and onboard composes a bash build script
+posix_only = unittest.skipIf(os.name == 'nt', 'needs POSIX executables and shell')
+
+
 def _write_stub(directory, name, body):
     path = os.path.join(directory, name)
     with open(path, 'w') as f:
@@ -55,6 +59,7 @@ def test_defsym_extraction_dedupes_preserving_first_seen_order(self):
 
 
 class LinkCommand(unittest.TestCase):
+    @posix_only
     def test_asks_ninja_for_only_the_elfs_final_command(self):
         # -s: without it, a target's commands include helper executables' links
         # (pico-sdk's boot_stage2) whose linker scripts are not the elf's
@@ -145,6 +150,7 @@ def test_no_key_leaves_the_argv_alone(self):
                              ['membrowse', 'report', 'x'])
 
 
+@posix_only
 class ReportCli(unittest.TestCase):
     """End-to-end CLI tests: real `python3 tools/membrowse_cli.py report` subprocess,
     with a stub `membrowse` injected into PATH so the real tool is never invoked."""
@@ -327,6 +333,7 @@ def test_explicit_commits_omit_mutually_exclusive_count(self):
         cmd = cli.compose('b', 'device/x', 5, False, 'k', ['--commits', 'a b'])
         self.assertNotIn('5', cmd[:4])
 
+    @posix_only
     def test_each_historical_build_fetches_its_own_deps_and_linker_settings(self):
         cmd = cli.compose('b', 'device/x', 5, False, 'k', [])
         i = cmd.index('--ld-scripts')
@@ -350,6 +357,7 @@ def test_uses_each_builds_scripts_and_defsyms(self):
             with open(out) as f:
                 self.assertEqual(f.read(), 'FLASH_SIZE = 256K;\nINCLUDE "/tree/board.ld"\n')
 
+    @posix_only
     def test_explicit_scripts_are_resolved_from_the_build_dir(self):
         with tempfile.TemporaryDirectory() as tmp:
             build = os.path.join(tmp, 'build')
@@ -368,6 +376,7 @@ def test_explicit_scripts_are_resolved_from_the_build_dir(self):
                                  f'INCLUDE "{script_dir}/memory.ld"\n'
                                  f'INCLUDE "{script_dir}/sections.ld"\n')
 
+    @posix_only
     def test_subcommand_runs_as_onboards_build_script_calls_it(self):
         # the historical build script runs `<python> <abs membrowse_cli.py> linker-shim ninja ...`
         with tempfile.TemporaryDirectory() as tmp:
@@ -390,6 +399,7 @@ def test_subcommand_is_hidden_from_help(self):
         self.assertNotIn('linker-shim', r.stdout)
 
 
+@posix_only
 class DisposableWorktree(unittest.TestCase):
     """`membrowse onboard` checks out and `git clean -fdx`s every historical
     commit unconditionally, in whatever directory it runs (membrowse/utils/
diff --git a/tools/code_size.py b/tools/code_size.py
index adaed78e0a..6fc256c886 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -971,7 +971,10 @@ def build_error(ret, src_dir):
              if line.strip() and not _NINJA_PROGRESS.match(line)
              and not line.startswith(('ninja: build stopped', 'ninja: Entering directory', 'FAILED: '))]
     error = build_utils.first_error(out) or (lines[-1] if lines else 'no output')
-    return error.replace(src_dir.rstrip(os.sep) + os.sep, '')
+    root = src_dir.rstrip(os.sep)
+    for prefix in {root + os.sep, root.replace(os.sep, '/') + '/'}:  # Windows: CMake passes the compiler D:/a/...
+        error = error.replace(prefix, '')
+    return error
 
 
 ESP_IDF_IMAGE = 'espressif/idf:tinyusb'  # .github/actions/setup_toolchain/espressif's tag

From 965e130fbfe410bbd3934d025d969812ef9b5b4a Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 01:02:27 +0700
Subject: [PATCH 04/18] code_size: normalize Windows filters once at entry,
 trim the Windows smoke job

---
 .github/workflows/code_size_windows.yml | 30 ++++++++++++-------------
 test/hil/test/test_code_size.py         |  3 ++-
 tools/code_size.py                      | 16 +++++++------
 3 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
index b80fd3c03b..adabe7db7c 100644
--- a/.github/workflows/code_size_windows.yml
+++ b/.github/workflows/code_size_windows.yml
@@ -19,6 +19,10 @@ permissions:
   contents: read
   actions: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event_name == 'push' && github.sha || github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
+
 env:
   PYTHONUTF8: '1'
 
@@ -27,8 +31,10 @@ jobs:
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v6
-      - run: python -m pip install pytest pyyaml pyelftools
-      - run: python -m pytest -q test/hil/test/test_code_size.py test/hil/test/test_code_size_ci.py test/hil/test/test_membrowse_cli.py
+      - run: python -m pip install pyyaml pyelftools
+      # as pre-commit's unit-test hook runs them
+      - run: python -m unittest -q test_code_size test_code_size_ci test_membrowse_cli
+        working-directory: test/hil/test
 
   smoke:
     runs-on: windows-latest
@@ -53,29 +59,23 @@ jobs:
       - name: Get Dependencies
         uses: ./.github/actions/get_deps
         with:
-          arg: '-b stm32f407disco'
+          arg: '-b ${{ env.BOARD }}'
 
       - name: Install membrowse
         run: 'python -m pip install --only-binary :all: membrowse==1.2.12'
 
+      # report exits 1 unless complete with TinyUSB files matched
       - name: Report
-        run: |
-          python tools/code_size.py report -b $BOARD -e $EXAMPLE --json
-          python - <<'EOF'
-          import json
-          data = json.load(open('cmake-code-size/stm32f407disco/report_device_cdc_msc.json'))
-          files = {f for e in data['elfs'] for f in e['sizes']['files']}
-          print(data['status'], sorted(files))
-          assert data['status'] == 'complete' and any(f.endswith('usbd.c') for f in files), 'no TinyUSB files'
-          EOF
+        run: python tools/code_size.py report -b $BOARD -e $EXAMPLE
 
       - name: Diff against a local base
         run: |
           python tools/code_size.py diff -b $BOARD -e $EXAMPLE --base-source local --base-branch HEAD --json
           python - <<'EOF'
-          import json
-          data = json.load(open('cmake-code-size/stm32f407disco/diff_device_cdc_msc.json'))
-          assert data['status'] == 'complete' and data['pairs'], data['status']
+          import json, os
+          path = f"cmake-code-size/{os.environ['BOARD']}/diff_{os.environ['EXAMPLE'].replace('/', '_')}.json"
+          data = json.load(open(path))
+          assert data['status'] == 'complete', data['status']
           assert all(p['base']['files'] == p['current']['files'] for p in data['pairs']), 'HEAD vs HEAD changed'
           EOF
 
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 1111951e29..66f753e639 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1264,7 +1264,8 @@ def test_the_root_matches_its_own_filter_through_a_symlink(self):
 class WindowsHost(unittest.TestCase):
     def test_a_backslash_object_path_matches_the_forward_slash_filter(self):
         for f in ('/a/tinyusb/src/', '\\a\\tinyusb\\src\\'):
-            self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\a\tinyusb\src\device\usbd.c.obj', [f]), 'device/usbd.c')
+            self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\a\tinyusb\src\device\usbd.c.obj', [sd.filter_arg(f)]),
+                             'device/usbd.c')
 
     def test_espressif_boards_are_refused(self):
         self.assertRegex(sd.esp_without_idf(['espressif_s3_devkitc', 'stm32f407disco']),
diff --git a/tools/code_size.py b/tools/code_size.py
index 6fc256c886..e318793f59 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -63,8 +63,7 @@
 WINDOWS = os.name == 'nt'
 # a master run's snapshots are the same for every checkout; XDG ignores a relative XDG_CACHE_HOME
 _cache_home = os.environ.get('LOCALAPPDATA' if WINDOWS else 'XDG_CACHE_HOME', '')
-BASELINE_CACHE_DIR = os.path.join(_cache_home if os.path.isabs(_cache_home) else
-                                  os.path.expanduser('~/AppData/Local' if WINDOWS else '~/.cache'),
+BASELINE_CACHE_DIR = os.path.join(_cache_home if os.path.isabs(_cache_home) else os.path.expanduser('~/.cache'),
                                   'tinyusb', 'code-size-baseline')
 CI_PINNED_BOARDS = os.path.join(TINYUSB_ROOT, '.github', 'ci-pinned-boards.json')
 # a diff's side names when git cannot give their commit hashes
@@ -135,7 +134,6 @@ def _relative_key(src, filters):
     or None when no filter matches."""
     if WINDOWS:
         src = src.replace('\\', '/')
-        filters = [f.replace('\\', '/') for f in filters]
     for f in filters:
         idx = src.find(f)
         if idx < 0:
@@ -841,8 +839,12 @@ def tinyusb_src_filter(checkout_dir):
     in `checkout_dir`. The substring is the absolute path to the checkout's `src/`
     dir — collision-free with vendored deps (pico-sdk, lwip, FreeRTOS, etc.) which
     live at unrelated paths."""
-    path = os.path.realpath(os.path.join(checkout_dir, 'src')) + os.sep
-    # Windows: CMake names an out-of-tree object D_/a/.../src/x.c.obj and DWARF D:/a/...: match past the drive
+    return filter_arg(os.path.realpath(os.path.join(checkout_dir, 'src')) + os.sep)
+
+
+def filter_arg(path):
+    """A path filter in the form sizes are matched in: on Windows, past the drive with '/',
+    as CMake names an out-of-tree object D_/a/.../src/x.c.obj and DWARF D:/a/..."""
     return os.path.splitdrive(path)[1].replace('\\', '/') if WINDOWS else path
 
 
@@ -1856,7 +1858,7 @@ def main():
     common = argparse.ArgumentParser(add_help=False)
     common.add_argument('-b', '--board', action='append', default=[],
                         help='Board name (repeatable). Required unless diff --ci is given.')
-    common.add_argument('-f', '--filter', action='append', default=None,
+    common.add_argument('-f', '--filter', action='append', default=None, type=filter_arg,
                         help='Path-substring filter (repeatable). When given, '
                              'overrides the default and is applied to every build. '
                              'Default: each build\'s own absolute <checkout>/src/ path, '
@@ -1919,7 +1921,7 @@ def main():
                       help='CI event; pull_request reads base/head from the merge commit '
                            '(default: $GITHUB_EVENT_NAME, else push)')
     snap.add_argument('--build-outcome', default='success', help='The Build step\'s outcome, recorded as is')
-    snap.add_argument('-f', '--filter', action='append', default=None,
+    snap.add_argument('-f', '--filter', action='append', default=None, type=filter_arg,
                       help='Path-substring filter (repeatable); default: this checkout\'s <checkout>/src/')
     snap.add_argument('--symbols', action='store_true', help='Include each file\'s symbols')
     snap.add_argument('-v', '--verbose', action='store_true', help='Print commands')

From bd03114bbd0d5a7745db8d09b2dc592796c4c920 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 01:09:51 +0700
Subject: [PATCH 05/18] test_code_size: stop a real Windows grandchild on
 timeout

---
 test/hil/test/test_code_size.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 66f753e639..08f304ed8a 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1279,6 +1279,28 @@ def test_a_timeout_kills_the_command_tree(self):
         argv = taskkill.call_args.args[0]
         self.assertEqual(argv[:2] + argv[3:], ['taskkill', '/PID', '/T', '/F'])
 
+    @unittest.skipUnless(os.name == 'nt', 'a real Windows process tree')
+    def test_a_timeout_stops_a_grandchild_holding_the_pipes(self):
+        # as ninja's compilers do: terminate() alone stops only the direct child
+        parent = ('import subprocess, sys, time; '
+                  'p = subprocess.Popen([sys.executable, "-c", "import time; time.sleep(60)"], '
+                  'stdout=sys.stdout, stderr=sys.stderr); '
+                  'print(p.pid, flush=True); time.sleep(60)')
+        start = time.monotonic()
+        ret = sd.run([sys.executable, '-c', parent], timeout=5)
+        elapsed = time.monotonic() - start
+        pid = ret.stdout.strip()
+        try:
+            self.assertEqual(ret.returncode, 124)
+            self.assertTrue(pid.isdigit(), ret.stdout)
+            tasks = subprocess.run(['tasklist', '/FI', f'PID eq {pid}', '/FO', 'CSV', '/NH'],
+                                   capture_output=True, text=True, check=True, timeout=10).stdout
+            self.assertNotIn(f'"{pid}"', tasks)
+            self.assertLess(elapsed, 30)  # well before the grandchild's own exit
+        finally:
+            if pid.isdigit():
+                subprocess.run(['taskkill', '/PID', pid, '/F'], capture_output=True)
+
     def test_a_symlink_without_the_privilege_names_developer_mode(self):
         denied = OSError(22, 'A required privilege is not held by the client')
         denied.winerror = 1314

From a10770fdf824d2b2b1b9d0d72a720b6cf8721b3f Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 01:45:46 +0700
Subject: [PATCH 06/18] ci: run the Windows code-size job on master pushes and
 PRs only

---
 .github/workflows/code_size_windows.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
index adabe7db7c..be140b3bc6 100644
--- a/.github/workflows/code_size_windows.yml
+++ b/.github/workflows/code_size_windows.yml
@@ -12,7 +12,7 @@ on:
       - '.github/scripts/code_size_ci.py'
       - '.github/workflows/code_size_windows.yml'
   push:
-    branches: [ master, claude/code-size-windows ]
+    branches: [ master ]
     paths: *code_size_paths
 
 permissions:

From 846f40d199cc9da1ab6538101f943d66485fd0d6 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 01:48:30 +0700
Subject: [PATCH 07/18] code-size skill: document running on Windows

---
 .claude/skills/code-size/SKILL.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.claude/skills/code-size/SKILL.md b/.claude/skills/code-size/SKILL.md
index c340a4c094..46d45784e4 100644
--- a/.claude/skills/code-size/SKILL.md
+++ b/.claude/skills/code-size/SKILL.md
@@ -14,7 +14,7 @@ description: Use when sizing TinyUSB examples per file, section or symbol (repor
 | all examples, CI-pinned, combined | `python3 tools/code_size.py diff --ci`                         |
 | one tree, no diff                 | `python3 tools/code_size.py report -b BOARD -e device/cdc_msc` |
 
-By default the base comes from the master snapshots CI stored for `--base-branch`'s commit (`--baseline-repo`, default `hathach/tinyusb`, through your `gh` login; cached per master run in `${XDG_CACHE_HOME:-~/.cache}/tinyusb/code-size-baseline/`, shared by every checkout), else its nearest first-parent ancestor's; the `Base:` line names the commit used and how far back it is, and master changes after it count as yours. `--base-branch` means its tip; pass a merge-base SHA to diff against that. When the CI base cannot be had (no `gh` or login, no stored run within 30 commits, a base off master, a failed download) or `-f`, `--bloaty` or another `--engine` needs an elf, the base is built locally in a temporary worktree and the report's `Base:` line says why; `--base-source ci` fails instead, `--base-source local` always builds and makes no GitHub call. Against a CI base, a board whose compiler or membrowse version differs from yours, or is unknown, is still compared with a warning naming both. A local diff never builds CI's `-DMA` variants; DMA-path changes are measured only by the PR's CI comment. A local base worktree symlinks this checkout's fetched dependencies, so a `tools/get_deps.py` pin bump's own size change is not in its diff, while a CI base was built with CI's. A local `report` or `diff` cannot size a `-D` variant build.
+By default the base comes from the master snapshots CI stored for `--base-branch`'s commit (`--baseline-repo`, default `hathach/tinyusb`, through your `gh` login; cached per master run in `${XDG_CACHE_HOME:-~/.cache}/tinyusb/code-size-baseline/` (`%LOCALAPPDATA%` on Windows), shared by every checkout), else its nearest first-parent ancestor's; the `Base:` line names the commit used and how far back it is, and master changes after it count as yours. `--base-branch` means its tip; pass a merge-base SHA to diff against that. When the CI base cannot be had (no `gh` or login, no stored run within 30 commits, a base off master, a failed download) or `-f`, `--bloaty` or another `--engine` needs an elf, the base is built locally in a temporary worktree and the report's `Base:` line says why; `--base-source ci` fails instead, `--base-source local` always builds and makes no GitHub call. Against a CI base, a board whose compiler or membrowse version differs from yours, or is unknown, is still compared with a warning naming both. A local diff never builds CI's `-DMA` variants; DMA-path changes are measured only by the PR's CI comment. A local base worktree symlinks this checkout's fetched dependencies, so a `tools/get_deps.py` pin bump's own size change is not in its diff, while a CI base was built with CI's. A local `report` or `diff` cannot size a `-D` variant build.
 
 ## Setup and choices
 
@@ -25,6 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
 
 ## Results
 

From 0b86154996c007e2f39c2aee6cb8fea4a3a67f4e Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sat, 3 Oct 2026 23:50:39 +0700
Subject: [PATCH 08/18] code_size: match filters case-insensitively on Windows

---
 test/hil/test/test_code_size.py | 4 ++++
 tools/code_size.py              | 7 ++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 08f304ed8a..3120e591d5 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1267,6 +1267,10 @@ def test_a_backslash_object_path_matches_the_forward_slash_filter(self):
             self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\a\tinyusb\src\device\usbd.c.obj', [sd.filter_arg(f)]),
                              'device/usbd.c')
 
+    def test_a_filter_matches_regardless_of_case_and_the_key_keeps_the_recorded_case(self):
+        self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\A\TinyUSB\src\Device\usbd.c.obj',
+                                          ['/nomatch/', '/a/tinyusb/src/']), 'Device/usbd.c')
+
     def test_espressif_boards_are_refused(self):
         self.assertRegex(sd.esp_without_idf(['espressif_s3_devkitc', 'stm32f407disco']),
                          r'^espressif_s3_devkitc need ESP-IDF, .* not support on Windows')
diff --git a/tools/code_size.py b/tools/code_size.py
index e318793f59..f44a08fac7 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -135,10 +135,11 @@ def _relative_key(src, filters):
     if WINDOWS:
         src = src.replace('\\', '/')
     for f in filters:
-        idx = src.find(f)
-        if idx < 0:
+        # Windows paths are case-insensitive; the key keeps the recorded case
+        m = re.search(re.escape(f), src, re.IGNORECASE if WINDOWS else 0)
+        if not m:
             continue
-        key = src[idx + len(f):]
+        key = src[m.end():]
         for suffix in ('.obj', '.o'):
             if key.endswith(suffix):
                 return key[:-len(suffix)]

From 030f5bf195b547ca319d9ef76193d59e9a830ce1 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:12:23 +0700
Subject: [PATCH 09/18] code_size: name a Windows compiler without .exe

---
 test/hil/test/test_code_size.py | 7 +++++++
 tools/code_size.py              | 4 +++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 3120e591d5..4a552d1fe5 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -2090,6 +2090,13 @@ def test_compiler_comes_from_cmake_not_the_host(self):
                                                        'name': 'arm-none-eabi-gcc', 'build_type': 'MinSizeRel'})
         self.assertEqual(sd._cmake_compiler('/nonexistent'), {'id': '', 'version': '', 'name': '', 'build_type': ''})
 
+    def test_a_windows_compiler_is_named_without_exe(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            os.makedirs(os.path.join(tmp, 'CMakeFiles', '4.1.2'))
+            with open(os.path.join(tmp, 'CMakeFiles', '4.1.2', 'CMakeCCompiler.cmake'), 'w') as f:
+                f.write('set(CMAKE_C_COMPILER "C:/arm/bin/arm-none-eabi-gcc.EXE")\n')
+            self.assertEqual(sd._cmake_compiler(tmp)['name'], 'arm-none-eabi-gcc')
+
     def test_an_esp_idf_board_reads_its_first_example_project(self):
         with tempfile.TemporaryDirectory() as tmp:
             for ex, ver in (('device/b', '14.2.0'), ('device/a', '14.2.0'), ('device/a/bootloader', '1.0')):
diff --git a/tools/code_size.py b/tools/code_size.py
index f44a08fac7..1159d3e1a7 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -1319,7 +1319,9 @@ def _cmake_compiler(build_dir):
                          ('name', 'CMAKE_C_COMPILER')):
             m = re.search(rf'^set\({var} "([^"]*)"\)', text, re.M)
             if m:
-                info[key] = os.path.basename(m.group(1)) if key == 'name' else m.group(1)
+                info[key] = m.group(1)
+    # without .exe, so a Windows build's name matches a Linux snapshot's
+    info['name'] = re.sub(r'\.exe$', '', os.path.basename(info['name']), flags=re.I)
     cache = os.path.join(build_dir, 'CMakeCache.txt')
     if os.path.isfile(cache):
         with open(cache) as f:

From 39b98961dc11faa91ddab4d7ca119a47a4f5474d Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:14:14 +0700
Subject: [PATCH 10/18] code_size: fail on a CMake-shortened object path on
 Windows

---
 .claude/skills/code-size/SKILL.md | 2 +-
 test/hil/test/test_code_size.py   | 7 +++++++
 tools/code_size.py                | 9 +++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/.claude/skills/code-size/SKILL.md b/.claude/skills/code-size/SKILL.md
index 46d45784e4..7342da6732 100644
--- a/.claude/skills/code-size/SKILL.md
+++ b/.claude/skills/code-size/SKILL.md
@@ -25,7 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
-- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated. A deep checkout path, deeper still for a local base built under `cmake-code-size/_worktree`, can push object paths past CMake's 250-character limit, which fails sizing; use a shorter checkout path.
 
 ## Results
 
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 4a552d1fe5..a6d74f85ac 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1271,6 +1271,13 @@ def test_a_filter_matches_regardless_of_case_and_the_key_keeps_the_recorded_case
         self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\A\TinyUSB\src\Device\usbd.c.obj',
                                           ['/nomatch/', '/a/tinyusb/src/']), 'Device/usbd.c')
 
+    def test_an_md5_shortened_object_path_fails_naming_the_cmake_limit(self):
+        shortened = r'cdc_msc.dir\0123456789abcdef0123456789abcdef\claude\cs\src\device\usbd.c.obj'
+        with self.assertRaisesRegex(RuntimeError, 'CMAKE_OBJECT_PATH_MAX .* shorter checkout path'):
+            sd._Sizes(['/Users/u/tinyusb/.worktrees/claude/cs/src/']).add(shortened, '.text', {'flash'}, 4, 'f')
+        with mock.patch.object(sd, 'WINDOWS', new=False):
+            sd._Sizes(['/nomatch/']).add(shortened.replace('\\', '/'), '.text', {'flash'}, 4, 'f')
+
     def test_espressif_boards_are_refused(self):
         self.assertRegex(sd.esp_without_idf(['espressif_s3_devkitc', 'stm32f407disco']),
                          r'^espressif_s3_devkitc need ESP-IDF, .* not support on Windows')
diff --git a/tools/code_size.py b/tools/code_size.py
index 1159d3e1a7..46342fc71d 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -272,6 +272,11 @@ def _esp_idf_buckets(sections):
     return buckets
 
 
+# CMake replaces the start of an over-long object name with its md5 (cmLocalGenerator.cxx,
+# cmLocalGeneratorShortenObjectName): <target>.dir/<md5>/<rest of the source path>.obj
+_SHORTENED_OBJECT_RE = re.compile(r'\.dir/[0-9a-f]{32}/')
+
+
 class _Sizes:
     """Accumulates one elf's filtered per-file flash/RAM, section and symbol sizes,
     and its total flash/RAM."""
@@ -281,6 +286,10 @@ def __init__(self, filters):
 
     def add(self, path, section, buckets, size, name):
         key = _relative_key(path, self.filters) if path else None
+        if key is None and path and WINDOWS and _SHORTENED_OBJECT_RE.search(path.replace('\\', '/')):
+            raise RuntimeError(f'{path}: CMake shortened this object path to fit CMAKE_OBJECT_PATH_MAX '
+                               '(250 on Windows), hiding its source dir from the filters - '
+                               'use a shorter checkout path')
         for b in buckets:
             self.all[b] += size
             if key is not None:

From ebad350c0b9d673ede9fb19d581a251c664ee57a Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:16:05 +0700
Subject: [PATCH 11/18] code_size: accept a backslash example on Windows

---
 test/hil/test/test_code_size.py | 8 ++++++++
 tools/code_size.py              | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index a6d74f85ac..5c43faf46f 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -10,6 +10,7 @@
 import functools
 import io
 import json
+import ntpath
 import os
 import re
 import shutil
@@ -1267,6 +1268,13 @@ def test_a_backslash_object_path_matches_the_forward_slash_filter(self):
             self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\a\tinyusb\src\device\usbd.c.obj', [sd.filter_arg(f)]),
                              'device/usbd.c')
 
+    def test_a_drive_is_stripped_from_a_filter(self):
+        with mock.patch.object(sd.os, 'path', ntpath):
+            self.assertEqual(sd.filter_arg('D:\\a\\tinyusb\\src\\'), '/a/tinyusb/src/')
+
+    def test_a_backslash_example_names_the_forward_slash_elf_id(self):
+        self.assertEqual(sd.example_arg('device\\cdc_msc\\'), 'device/cdc_msc')
+
     def test_a_filter_matches_regardless_of_case_and_the_key_keeps_the_recorded_case(self):
         self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\A\TinyUSB\src\Device\usbd.c.obj',
                                           ['/nomatch/', '/a/tinyusb/src/']), 'Device/usbd.c')
diff --git a/tools/code_size.py b/tools/code_size.py
index 46342fc71d..d957c779e5 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -1858,7 +1858,7 @@ def show(c):
 
 
 def example_arg(value):
-    example = value.rstrip('/')
+    example = (value.replace('\\', '/') if WINDOWS else value).rstrip('/')
     if not example:
         raise argparse.ArgumentTypeError(f'{value!r} names no example')
     return example

From 7aa7241f805391678b2e6fd92dba0743ddd5a10c Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:17:35 +0700
Subject: [PATCH 12/18] test_ci_select: assert the Windows code-size workflow
 is metadata

---
 test/hil/test/test_ci_select.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/test/hil/test/test_ci_select.py b/test/hil/test/test_ci_select.py
index 35e7a8e59e..d23add521a 100644
--- a/test/hil/test/test_ci_select.py
+++ b/test/hil/test/test_ci_select.py
@@ -1875,7 +1875,8 @@ def test_repo_metadata_is_not_a_build_input(self):
                   '.clang-format', '.idea/misc.xml', 'version.yml', 'library.json',
                   'examples/CMakePresets.json', 'test/fuzz/fuzz.cc',
                   'test/unit-test/project.yml', '.github/workflows/pr_comment.yml',
-                  '.github/scripts/code_size_ci.py', '.claude/skills/build-doc/scripts/gen_doc.py', '.agents'):
+                  '.github/workflows/code_size_windows.yml', '.github/scripts/code_size_ci.py',
+                  '.claude/skills/build-doc/scripts/gen_doc.py', '.agents'):
             s = self.b([p])
             self.assertFalse(s['full'], p)
             self.assertEqual(s['families'], [], p)

From 8fdedadab45e9c3d3ed79c63f666b020f08b90b6 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:33:31 +0700
Subject: [PATCH 13/18] code_size: resolve a CMake-shortened object's source
 through build.ninja

---
 .claude/skills/code-size/SKILL.md |  2 +-
 test/hil/test/test_code_size.py   | 74 ++++++++++++++++++++++++++++---
 tools/code_size.py                | 40 +++++++++++++----
 3 files changed, 100 insertions(+), 16 deletions(-)

diff --git a/.claude/skills/code-size/SKILL.md b/.claude/skills/code-size/SKILL.md
index 7342da6732..46d45784e4 100644
--- a/.claude/skills/code-size/SKILL.md
+++ b/.claude/skills/code-size/SKILL.md
@@ -25,7 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
-- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated. A deep checkout path, deeper still for a local base built under `cmake-code-size/_worktree`, can push object paths past CMake's 250-character limit, which fails sizing; use a shorter checkout path.
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
 
 ## Results
 
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 5c43faf46f..8852fd71b4 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -8,6 +8,7 @@
 import contextlib
 import errno
 import functools
+import hashlib
 import io
 import json
 import ntpath
@@ -1261,6 +1262,72 @@ def test_the_root_matches_its_own_filter_through_a_symlink(self):
         self.assertEqual(out, 'True\n')
 
 
+def cmake_shortened(obj_dir, obj_name):
+    """CMake v4.1.2 cmLocalGeneratorCheckObjectName and cmLocalGeneratorShortenObjectName
+    (Source/cmLocalGenerator.cxx) at Windows' CMAKE_OBJECT_PATH_MAX of 250."""
+    max_len = 250 - len(obj_dir)
+    if len(obj_name) <= max_len:
+        return obj_name
+    pos = obj_name.find('/', len(obj_name) - max_len + 32)
+    return hashlib.md5(obj_name[:pos].encode()).hexdigest() + obj_name[pos:]
+
+
+@mock.patch.object(sd, 'WINDOWS', new=True)
+class CMakeShortenedObject(unittest.TestCase):
+    CHECKOUT = 'C:/Users/username/code/tinyusb/.worktrees/claude/code-size-windows/cmake-code-size/_worktree'
+    BUILD = 'C:/Users/username/code/tinyusb/.worktrees/claude/code-size-windows/cmake-code-size/base/'
+    TARGET = 'device/audio_4_channel_mic_freertos/CMakeFiles/audio_4_channel_mic_freertos.dir/'
+    FILTER = CHECKOUT[2:] + '/src/'
+    USBD = CHECKOUT + '/src/device/usbd.c'
+    STARTUP = CHECKOUT + '/hw/mcu/st/cmsis_device_f4/Source/Templates/gcc/startup_stm32f407xx.s'
+
+    def setUp(self):
+        tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(tmp.cleanup)
+        self.build_dir = tmp.name
+        self.elf = os.path.join(tmp.name, 'device', 'audio_4_channel_mic_freertos', 'audio_4_channel_mic_freertos.elf')
+
+    def obj(self, source):
+        """The map path of source's object, and its build.ninja compile edge."""
+        obj = self.TARGET + cmake_shortened(self.BUILD + self.TARGET, source.replace(':', '_') + '.obj')
+        self.assertRegex(obj, r'\.dir/[0-9a-f]{32}/')
+        self.assertNotIn(self.FILTER, obj)
+        edge = f'build {obj}: C_COMPILER__audio_4_channel_mic_freertos_unscanned_MinSizeRel {source.replace(":", "$:")}' \
+               ' || cmake_object_order_depends_target_audio_4_channel_mic_freertos\n'
+        return obj.replace('/', '\\'), edge
+
+    def sizes(self, edges):
+        with open(os.path.join(self.build_dir, 'build.ninja'), 'w') as f:
+            f.writelines(edges)
+        return sd._Sizes([self.FILTER], self.elf)
+
+    def test_a_shortened_vendor_object_counts_in_all_only(self):
+        obj, edge = self.obj(self.STARTUP)
+        sizes = self.sizes([edge])
+        sizes.add(obj, '.isr_vector', {'flash'}, 4, 'g_pfnVectors')
+        self.assertEqual(sizes.result()['files'], {})
+        self.assertEqual(sizes.result()['all'], {'flash': 4, 'ram': 0})
+
+    def test_a_shortened_tinyusb_object_keeps_its_source_key(self):
+        obj, edge = self.obj(self.USBD)
+        sizes = self.sizes([edge])
+        sizes.add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
+        self.assertEqual(sizes.result()['files'], {'device/usbd.c': {'flash': 4, 'ram': 0}})
+
+    def test_a_shortened_object_build_ninja_does_not_build_fails(self):
+        obj, _ = self.obj(self.USBD)
+        _, edge = self.obj(self.STARTUP)
+        with self.assertRaisesRegex(RuntimeError, 'CMAKE_OBJECT_PATH_MAX .* no compile edge'):
+            self.sizes([edge]).add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
+
+    def test_linux_does_not_resolve_a_shortened_object(self):
+        obj, _ = self.obj(self.USBD)
+        with mock.patch.object(sd, 'WINDOWS', new=False):
+            sizes = self.sizes([])
+            sizes.add(obj.replace('\\', '/'), '.text', {'flash'}, 4, 'tud_task_ext')
+        self.assertEqual(sizes.result()['files'], {})
+
+
 @mock.patch.object(sd, 'WINDOWS', new=True)
 class WindowsHost(unittest.TestCase):
     def test_a_backslash_object_path_matches_the_forward_slash_filter(self):
@@ -1279,13 +1346,6 @@ def test_a_filter_matches_regardless_of_case_and_the_key_keeps_the_recorded_case
         self.assertEqual(sd._relative_key(r'cdc_msc.dir\D_\A\TinyUSB\src\Device\usbd.c.obj',
                                           ['/nomatch/', '/a/tinyusb/src/']), 'Device/usbd.c')
 
-    def test_an_md5_shortened_object_path_fails_naming_the_cmake_limit(self):
-        shortened = r'cdc_msc.dir\0123456789abcdef0123456789abcdef\claude\cs\src\device\usbd.c.obj'
-        with self.assertRaisesRegex(RuntimeError, 'CMAKE_OBJECT_PATH_MAX .* shorter checkout path'):
-            sd._Sizes(['/Users/u/tinyusb/.worktrees/claude/cs/src/']).add(shortened, '.text', {'flash'}, 4, 'f')
-        with mock.patch.object(sd, 'WINDOWS', new=False):
-            sd._Sizes(['/nomatch/']).add(shortened.replace('\\', '/'), '.text', {'flash'}, 4, 'f')
-
     def test_espressif_boards_are_refused(self):
         self.assertRegex(sd.esp_without_idf(['espressif_s3_devkitc', 'stm32f407disco']),
                          r'^espressif_s3_devkitc need ESP-IDF, .* not support on Windows')
diff --git a/tools/code_size.py b/tools/code_size.py
index d957c779e5..9481239789 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -275,21 +275,45 @@ def _esp_idf_buckets(sections):
 # CMake replaces the start of an over-long object name with its md5 (cmLocalGenerator.cxx,
 # cmLocalGeneratorShortenObjectName): <target>.dir/<md5>/<rest of the source path>.obj
 _SHORTENED_OBJECT_RE = re.compile(r'\.dir/[0-9a-f]{32}/')
+# first output, rule and first input of a build.ninja edge; '$' escapes a path's ':' and ' '
+_NINJA_EDGE_RE = re.compile(r'build ((?:[^$:\s]|\$.)+)(?: (?:[^$:]|\$.)*)?: \S+ ((?:[^$\s]|\$.)+)')
+
+
+@functools.lru_cache(maxsize=None)
+def _shortened_object_sources(build_dir):
+    """{shortened object: source} of the compile edges in build_dir's build.ninja."""
+    sources = {}
+    with open(os.path.join(build_dir, 'build.ninja'), encoding='utf-8') as f:
+        for line in f:
+            m = _NINJA_EDGE_RE.match(line)
+            if m and _SHORTENED_OBJECT_RE.search(m[1]):
+                obj, src = (re.sub(r'\$(.)', r'\1', p).replace('\\', '/') for p in m.groups())
+                sources[obj] = src
+    return sources
 
 
 class _Sizes:
     """Accumulates one elf's filtered per-file flash/RAM, section and symbol sizes,
     and its total flash/RAM."""
-    def __init__(self, filters):
-        self.filters, self.files, self.all = filters, {}, {'flash': 0, 'ram': 0}
+    def __init__(self, filters, elf):
+        self.filters, self.elf, self.files, self.all = filters, elf, {}, {'flash': 0, 'ram': 0}
         self.sections, self.symbols = {}, {}
 
+    def _shortened_key(self, path):
+        """Key of the source build.ninja compiles to a CMake-shortened object; the object
+        path no longer holds the filtered dir."""
+        build_dir = _find_ninja_build_dir(self.elf)
+        src = build_dir and _shortened_object_sources(build_dir).get(path.replace('\\', '/'))
+        if not src:
+            raise RuntimeError(f'{path}: CMake shortened this object path to fit CMAKE_OBJECT_PATH_MAX '
+                               f'(250 on Windows) and the build.ninja above {self.elf} has no compile edge '
+                               'for it to name its source - use a shorter checkout path')
+        return _relative_key(src, self.filters)
+
     def add(self, path, section, buckets, size, name):
         key = _relative_key(path, self.filters) if path else None
         if key is None and path and WINDOWS and _SHORTENED_OBJECT_RE.search(path.replace('\\', '/')):
-            raise RuntimeError(f'{path}: CMake shortened this object path to fit CMAKE_OBJECT_PATH_MAX '
-                               '(250 on Windows), hiding its source dir from the filters - '
-                               'use a shorter checkout path')
+            key = self._shortened_key(path)
         for b in buckets:
             self.all[b] += size
             if key is not None:
@@ -346,7 +370,7 @@ def membrowse_sizes(elf, filters):
     """Symbols of `membrowse report`; linker-defined symbols without a section
     (`__StackLimit`) are not counted."""
     buckets = section_buckets(elf, _map_path(elf))
-    sizes = _Sizes(filters)
+    sizes = _Sizes(filters, elf)
     for sym in report_for_elf(elf).get('symbols', []):
         section = sym.get('section')
         if not sym.get('size') or not section:
@@ -385,7 +409,7 @@ def linkermap_sizes(elf, filters):
         sections = _linkermap().parseSections(f)
     if sections is None:
         raise RuntimeError(f'{map_path}: no Memory Configuration, not a GNU ld map')
-    sizes = _Sizes(filters)
+    sizes = _Sizes(filters, elf)
     for out in sections:
         if not out.children:  # memory regions
             continue
@@ -407,7 +431,7 @@ def bloaty_sizes(elf, filters):
     if not {'compileunits', 'sections', 'symbols', 'vmsize'} <= set(rows.fieldnames or ()):
         raise RuntimeError(f'unexpected bloaty csv columns for {elf}: {rows.fieldnames}')
     buckets = section_buckets(elf, _map_path(elf))
-    sizes = _Sizes(filters)
+    sizes = _Sizes(filters, elf)
     for row in rows:
         section = row['sections']
         try:

From 44563dc00cd6ba9d51f9c5db2834998384311d68 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 00:47:42 +0700
Subject: [PATCH 14/18] code_size: fail an elf whose build.ninja cannot be read
 as UTF-8

---
 test/hil/test/test_code_size.py |  8 ++++++++
 tools/code_size.py              | 17 +++++++++++------
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 8852fd71b4..5731451aee 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1320,6 +1320,14 @@ def test_a_shortened_object_build_ninja_does_not_build_fails(self):
         with self.assertRaisesRegex(RuntimeError, 'CMAKE_OBJECT_PATH_MAX .* no compile edge'):
             self.sizes([edge]).add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
 
+    def test_a_build_ninja_not_in_utf_8_fails(self):
+        obj, edge = self.obj(self.USBD)
+        with open(os.path.join(self.build_dir, 'build.ninja'), 'wb') as f:
+            f.write(b'# Calf\xe9\n' + edge.encode())
+        sizes = sd._Sizes([self.FILTER], self.elf)
+        with self.assertRaisesRegex(RuntimeError, r'build\.ninja.*utf-8'):
+            sizes.add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
+
     def test_linux_does_not_resolve_a_shortened_object(self):
         obj, _ = self.obj(self.USBD)
         with mock.patch.object(sd, 'WINDOWS', new=False):
diff --git a/tools/code_size.py b/tools/code_size.py
index 9481239789..4d66d8f36a 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -282,13 +282,18 @@ def _esp_idf_buckets(sections):
 @functools.lru_cache(maxsize=None)
 def _shortened_object_sources(build_dir):
     """{shortened object: source} of the compile edges in build_dir's build.ninja."""
+    path = os.path.join(build_dir, 'build.ninja')
     sources = {}
-    with open(os.path.join(build_dir, 'build.ninja'), encoding='utf-8') as f:
-        for line in f:
-            m = _NINJA_EDGE_RE.match(line)
-            if m and _SHORTENED_OBJECT_RE.search(m[1]):
-                obj, src = (re.sub(r'\$(.)', r'\1', p).replace('\\', '/') for p in m.groups())
-                sources[obj] = src
+    # CMake writes it in the ANSI code page unless ninja >= 1.11 reports UTF-8 (`ninja -t wincodepage`)
+    try:
+        with open(path, encoding='utf-8') as f:
+            for line in f:
+                m = _NINJA_EDGE_RE.match(line)
+                if m and _SHORTENED_OBJECT_RE.search(m[1]):
+                    obj, src = (re.sub(r'\$(.)', r'\1', p).replace('\\', '/') for p in m.groups())
+                    sources[obj] = src
+    except (OSError, UnicodeDecodeError) as e:
+        raise RuntimeError(f'cannot read {path}: {e}') from e
     return sources
 
 

From d2f623b71302b86187dbfa581be5e2ec168e43b6 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 01:50:35 +0700
Subject: [PATCH 15/18] code_size: name the ninja >= 1.11 remedy for a
 non-UTF-8 build.ninja

---
 .claude/skills/code-size/SKILL.md | 2 +-
 test/hil/test/test_code_size.py   | 2 +-
 tools/code_size.py                | 7 +++++--
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/.claude/skills/code-size/SKILL.md b/.claude/skills/code-size/SKILL.md
index 46d45784e4..c3784bc806 100644
--- a/.claude/skills/code-size/SKILL.md
+++ b/.claude/skills/code-size/SKILL.md
@@ -25,7 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
-- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces, and a non-ASCII checkout path needs ninja >= 1.11 (UTF-8 `build.ninja`); espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
 
 ## Results
 
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index 5731451aee..d8b5810056 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1325,7 +1325,7 @@ def test_a_build_ninja_not_in_utf_8_fails(self):
         with open(os.path.join(self.build_dir, 'build.ninja'), 'wb') as f:
             f.write(b'# Calf\xe9\n' + edge.encode())
         sizes = sd._Sizes([self.FILTER], self.elf)
-        with self.assertRaisesRegex(RuntimeError, r'build\.ninja.*utf-8'):
+        with self.assertRaisesRegex(RuntimeError, r'build\.ninja is not UTF-8 .* use ninja >= 1\.11'):
             sizes.add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
 
     def test_linux_does_not_resolve_a_shortened_object(self):
diff --git a/tools/code_size.py b/tools/code_size.py
index 4d66d8f36a..44e01f580f 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -284,7 +284,6 @@ def _shortened_object_sources(build_dir):
     """{shortened object: source} of the compile edges in build_dir's build.ninja."""
     path = os.path.join(build_dir, 'build.ninja')
     sources = {}
-    # CMake writes it in the ANSI code page unless ninja >= 1.11 reports UTF-8 (`ninja -t wincodepage`)
     try:
         with open(path, encoding='utf-8') as f:
             for line in f:
@@ -292,8 +291,12 @@ def _shortened_object_sources(build_dir):
                 if m and _SHORTENED_OBJECT_RE.search(m[1]):
                     obj, src = (re.sub(r'\$(.)', r'\1', p).replace('\\', '/') for p in m.groups())
                     sources[obj] = src
-    except (OSError, UnicodeDecodeError) as e:
+    except OSError as e:
         raise RuntimeError(f'cannot read {path}: {e}') from e
+    except UnicodeDecodeError as e:
+        raise RuntimeError(f'{path} is not UTF-8 ({e}): CMake writes it in the ANSI code page when ninja is older '
+                           'than 1.11 or its code page is not UTF-8 (`ninja -t wincodepage`); use ninja >= 1.11 '
+                           'with a UTF-8 code page or an ASCII-only checkout path') from e
     return sources
 
 

From e53805051805a6423a4e6df71588e9762b365fcf Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Sun, 4 Oct 2026 02:01:24 +0700
Subject: [PATCH 16/18] code_size: key a shortened object by its source and
 sharpen its build.ninja errors

---
 .claude/skills/code-size/SKILL.md |  2 +-
 test/hil/test/test_code_size.py   | 22 +++++++++++++++++++---
 tools/code_size.py                | 25 +++++++++++++++----------
 3 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/.claude/skills/code-size/SKILL.md b/.claude/skills/code-size/SKILL.md
index c3784bc806..6b53b5189d 100644
--- a/.claude/skills/code-size/SKILL.md
+++ b/.claude/skills/code-size/SKILL.md
@@ -25,7 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
-- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces, and a non-ASCII checkout path needs ninja >= 1.11 (UTF-8 `build.ninja`); espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces, and a non-ASCII checkout, CMake or toolchain path needs ninja >= 1.11 whose `ninja -t wincodepage` reports UTF-8; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
 
 ## Results
 
diff --git a/test/hil/test/test_code_size.py b/test/hil/test/test_code_size.py
index d8b5810056..25a282df06 100644
--- a/test/hil/test/test_code_size.py
+++ b/test/hil/test/test_code_size.py
@@ -1279,6 +1279,7 @@ class CMakeShortenedObject(unittest.TestCase):
     TARGET = 'device/audio_4_channel_mic_freertos/CMakeFiles/audio_4_channel_mic_freertos.dir/'
     FILTER = CHECKOUT[2:] + '/src/'
     USBD = CHECKOUT + '/src/device/usbd.c'
+    CDC = CHECKOUT + '/src/class/cdc/cdc_device.c'
     STARTUP = CHECKOUT + '/hw/mcu/st/cmsis_device_f4/Source/Templates/gcc/startup_stm32f407xx.s'
 
     def setUp(self):
@@ -1296,10 +1297,10 @@ def obj(self, source):
                ' || cmake_object_order_depends_target_audio_4_channel_mic_freertos\n'
         return obj.replace('/', '\\'), edge
 
-    def sizes(self, edges):
+    def sizes(self, edges, filters=(FILTER,)):
         with open(os.path.join(self.build_dir, 'build.ninja'), 'w') as f:
             f.writelines(edges)
-        return sd._Sizes([self.FILTER], self.elf)
+        return sd._Sizes(list(filters), self.elf)
 
     def test_a_shortened_vendor_object_counts_in_all_only(self):
         obj, edge = self.obj(self.STARTUP)
@@ -1314,6 +1315,19 @@ def test_a_shortened_tinyusb_object_keeps_its_source_key(self):
         sizes.add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
         self.assertEqual(sizes.result()['files'], {'device/usbd.c': {'flash': 4, 'ram': 0}})
 
+    def test_a_later_filter_matching_the_kept_tail_keys_as_for_the_full_source(self):
+        obj, edge = self.obj(self.CDC)
+        self.assertIn('/class/cdc/', obj.replace('\\', '/'))
+        sizes = self.sizes([edge], (self.FILTER, 'class/'))
+        sizes.add(obj, '.text', {'flash'}, 4, 'tud_cdc_n_write')
+        self.assertEqual(sizes.result()['files'], {'class/cdc/cdc_device.c': {'flash': 4, 'ram': 0}})
+
+    def test_a_shortened_object_without_build_ninja_fails(self):
+        obj, _ = self.obj(self.USBD)
+        with mock.patch.object(sd, '_find_ninja_build_dir', return_value=None):
+            with self.assertRaisesRegex(RuntimeError, 'CMAKE_OBJECT_PATH_MAX .* no build\\.ninja was found above'):
+                sd._Sizes([self.FILTER], self.elf).add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
+
     def test_a_shortened_object_build_ninja_does_not_build_fails(self):
         obj, _ = self.obj(self.USBD)
         _, edge = self.obj(self.STARTUP)
@@ -1325,8 +1339,10 @@ def test_a_build_ninja_not_in_utf_8_fails(self):
         with open(os.path.join(self.build_dir, 'build.ninja'), 'wb') as f:
             f.write(b'# Calf\xe9\n' + edge.encode())
         sizes = sd._Sizes([self.FILTER], self.elf)
-        with self.assertRaisesRegex(RuntimeError, r'build\.ninja is not UTF-8 .* use ninja >= 1\.11'):
+        with self.assertRaisesRegex(RuntimeError, r'build\.ninja is not UTF-8: .* use ninja >= 1\.11 whose '
+                                    r'`ninja -t wincodepage` reports UTF-8') as cm:
             sizes.add(obj, '.text', {'flash'}, 4, 'tud_task_ext')
+        self.assertNotIn('position', str(cm.exception))  # relative to the decoder's chunk, not the file
 
     def test_linux_does_not_resolve_a_shortened_object(self):
         obj, _ = self.obj(self.USBD)
diff --git a/tools/code_size.py b/tools/code_size.py
index 44e01f580f..89e5692e89 100644
--- a/tools/code_size.py
+++ b/tools/code_size.py
@@ -294,9 +294,10 @@ def _shortened_object_sources(build_dir):
     except OSError as e:
         raise RuntimeError(f'cannot read {path}: {e}') from e
     except UnicodeDecodeError as e:
-        raise RuntimeError(f'{path} is not UTF-8 ({e}): CMake writes it in the ANSI code page when ninja is older '
-                           'than 1.11 or its code page is not UTF-8 (`ninja -t wincodepage`); use ninja >= 1.11 '
-                           'with a UTF-8 code page or an ASCII-only checkout path') from e
+        raise RuntimeError(f'{path} is not UTF-8: CMake writes it in the ANSI code page when ninja is older than '
+                           '1.11 or `ninja -t wincodepage` is not UTF-8; use ninja >= 1.11 whose '
+                           '`ninja -t wincodepage` reports UTF-8, or keep the checkout, CMake and toolchain paths '
+                           'ASCII-only') from e
     return sources
 
 
@@ -310,18 +311,22 @@ def __init__(self, filters, elf):
     def _shortened_key(self, path):
         """Key of the source build.ninja compiles to a CMake-shortened object; the object
         path no longer holds the filtered dir."""
+        shortened = f'{path}: CMake shortened this object path to fit CMAKE_OBJECT_PATH_MAX (250 on Windows) and'
         build_dir = _find_ninja_build_dir(self.elf)
-        src = build_dir and _shortened_object_sources(build_dir).get(path.replace('\\', '/'))
+        if build_dir is None:
+            raise RuntimeError(f'{shortened} no build.ninja was found above {self.elf} to name its source - '
+                               'use a shorter checkout path')
+        src = _shortened_object_sources(build_dir).get(path.replace('\\', '/'))
         if not src:
-            raise RuntimeError(f'{path}: CMake shortened this object path to fit CMAKE_OBJECT_PATH_MAX '
-                               f'(250 on Windows) and the build.ninja above {self.elf} has no compile edge '
-                               'for it to name its source - use a shorter checkout path')
+            raise RuntimeError(f'{shortened} the build.ninja above {self.elf} has no compile edge for it '
+                               'to name its source - use a shorter checkout path')
         return _relative_key(src, self.filters)
 
     def add(self, path, section, buckets, size, name):
-        key = _relative_key(path, self.filters) if path else None
-        if key is None and path and WINDOWS and _SHORTENED_OBJECT_RE.search(path.replace('\\', '/')):
-            key = self._shortened_key(path)
+        if path and WINDOWS and _SHORTENED_OBJECT_RE.search(path.replace('\\', '/')):
+            key = self._shortened_key(path)  # a filter could match the kept tail of the source path
+        else:
+            key = _relative_key(path, self.filters) if path else None
         for b in buckets:
             self.all[b] += size
             if key is not None:

From 197f63c675e78c843e79c7812e13401491988bae Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Mon, 5 Oct 2026 09:50:24 +0700
Subject: [PATCH 17/18] ci: check code_size.py in build-os's Windows leg
 instead of its own workflow

---
 .github/workflows/build.yml             |  1 +
 .github/workflows/build_util.yml        | 26 ++++++++
 .github/workflows/code_size_windows.yml | 83 -------------------------
 test/hil/test/test_ci_select.py         |  3 +-
 tools/ci_select.py                      |  2 +-
 5 files changed, 29 insertions(+), 86 deletions(-)
 delete mode 100644 .github/workflows/code_size_windows.yml

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 7d4a319c58..a05ec364fa 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -284,6 +284,7 @@ jobs:
       toolchain: 'arm-gcc-${{ matrix.os }}'
       build-args: '["stm32h7rs"]'
       build-options: '--one-random'
+      code-size-check: ${{ matrix.os == 'windows-latest' && matrix.build-system == 'cmake' && '-b stm32h7s3nucleo -e device/cdc_msc' || '' }}
 
   # ---------------------------------------
   # Zephyr
diff --git a/.github/workflows/build_util.yml b/.github/workflows/build_util.yml
index 5dcf92c824..b42c51f02a 100644
--- a/.github/workflows/build_util.yml
+++ b/.github/workflows/build_util.yml
@@ -36,6 +36,11 @@ on:
         required: false
         default: true
         type: boolean
+      code-size-check:
+        description: 'code_size.py -b/-e args to check tools/code_size.py on this host with'
+        required: false
+        default: ''
+        type: string
 
 jobs:
   family:
@@ -117,6 +122,27 @@ jobs:
           fi
         shell: bash
 
+      - name: Code size check
+        # code_size.py on a host CI never snapshots on (build-os's Windows leg); its diffs
+        # rebuild twice more, so only a manual run takes them
+        if: inputs.code-size-check != ''
+        env:
+          PYTHONUTF8: '1'
+          CHECK: ${{ inputs.code-size-check }}
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          python -m pip install --only-binary :all: membrowse==1.2.12 pyyaml pyelftools
+          (cd test/hil/test && python -m unittest -q test_code_size test_code_size_ci test_membrowse_cli)
+          python tools/code_size.py report $CHECK
+          if [ "$GITHUB_EVENT_NAME" = workflow_dispatch ]; then
+            git fetch -q --depth=1 origin master:refs/remotes/origin/master
+            python tools/code_size.py diff $CHECK --base-source local --base-branch HEAD --json
+            # diff passes a size change and some INCOMPLETE results; HEAD against HEAD must be neither
+            python -c "import glob, json; d = json.load(open(*glob.glob('cmake-code-size/*/diff_*.json'))); assert d['status'] == 'complete' and all(p['base']['files'] == p['current']['files'] for p in d['pairs']), d['status']"
+            python tools/code_size.py diff $CHECK --base-source ci --base-branch origin/master
+          fi
+        shell: bash
+
       - name: Code size snapshot
         id: code-size
         # measurement only: it also runs after a failed Build and records that in the
diff --git a/.github/workflows/code_size_windows.yml b/.github/workflows/code_size_windows.yml
deleted file mode 100644
index be140b3bc6..0000000000
--- a/.github/workflows/code_size_windows.yml
+++ /dev/null
@@ -1,83 +0,0 @@
-name: Code size on Windows
-
-on:
-  workflow_dispatch:
-  pull_request:
-    paths: &code_size_paths
-      - 'tools/code_size.py'
-      - 'tools/membrowse_cli.py'
-      - 'tools/build_utils.py'
-      - 'test/hil/test/test_code_size*.py'
-      - 'test/hil/test/test_membrowse_cli.py'
-      - '.github/scripts/code_size_ci.py'
-      - '.github/workflows/code_size_windows.yml'
-  push:
-    branches: [ master ]
-    paths: *code_size_paths
-
-permissions:
-  contents: read
-  actions: read
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.event_name == 'push' && github.sha || github.ref }}
-  cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}
-
-env:
-  PYTHONUTF8: '1'
-
-jobs:
-  unit-test:
-    runs-on: windows-latest
-    steps:
-      - uses: actions/checkout@v6
-      - run: python -m pip install pyyaml pyelftools
-      # as pre-commit's unit-test hook runs them
-      - run: python -m unittest -q test_code_size test_code_size_ci test_membrowse_cli
-        working-directory: test/hil/test
-
-  smoke:
-    runs-on: windows-latest
-    env:
-      BOARD: stm32f407disco
-      EXAMPLE: device/cdc_msc
-      GH_TOKEN: ${{ github.token }}
-    defaults:
-      run:
-        shell: bash
-    steps:
-      - name: Checkout TinyUSB
-        uses: actions/checkout@v6
-        with:
-          fetch-depth: 0
-
-      - name: Setup Toolchain
-        uses: ./.github/actions/setup_toolchain
-        with:
-          toolchain: 'arm-gcc-windows-latest'
-
-      - name: Get Dependencies
-        uses: ./.github/actions/get_deps
-        with:
-          arg: '-b ${{ env.BOARD }}'
-
-      - name: Install membrowse
-        run: 'python -m pip install --only-binary :all: membrowse==1.2.12'
-
-      # report exits 1 unless complete with TinyUSB files matched
-      - name: Report
-        run: python tools/code_size.py report -b $BOARD -e $EXAMPLE
-
-      - name: Diff against a local base
-        run: |
-          python tools/code_size.py diff -b $BOARD -e $EXAMPLE --base-source local --base-branch HEAD --json
-          python - <<'EOF'
-          import json, os
-          path = f"cmake-code-size/{os.environ['BOARD']}/diff_{os.environ['EXAMPLE'].replace('/', '_')}.json"
-          data = json.load(open(path))
-          assert data['status'] == 'complete', data['status']
-          assert all(p['base']['files'] == p['current']['files'] for p in data['pairs']), 'HEAD vs HEAD changed'
-          EOF
-
-      - name: Diff against CI snapshots
-        run: python tools/code_size.py diff -b $BOARD -e $EXAMPLE --base-source ci --base-branch origin/master
diff --git a/test/hil/test/test_ci_select.py b/test/hil/test/test_ci_select.py
index d23add521a..35e7a8e59e 100644
--- a/test/hil/test/test_ci_select.py
+++ b/test/hil/test/test_ci_select.py
@@ -1875,8 +1875,7 @@ def test_repo_metadata_is_not_a_build_input(self):
                   '.clang-format', '.idea/misc.xml', 'version.yml', 'library.json',
                   'examples/CMakePresets.json', 'test/fuzz/fuzz.cc',
                   'test/unit-test/project.yml', '.github/workflows/pr_comment.yml',
-                  '.github/workflows/code_size_windows.yml', '.github/scripts/code_size_ci.py',
-                  '.claude/skills/build-doc/scripts/gen_doc.py', '.agents'):
+                  '.github/scripts/code_size_ci.py', '.claude/skills/build-doc/scripts/gen_doc.py', '.agents'):
             s = self.b([p])
             self.assertFalse(s['full'], p)
             self.assertEqual(s['families'], [], p)
diff --git a/tools/ci_select.py b/tools/ci_select.py
index e140663629..e7e989e27a 100755
--- a/tools/ci_select.py
+++ b/tools/ci_select.py
@@ -122,7 +122,7 @@ def _read(path: str) -> str:
     # .github, minus the build machinery named in _FULL_RE and _CI_BOARDS_RE
     r'\.github/(FUNDING\.yml$|labeler\.yml$|'
     r'ISSUE_TEMPLATE/|scripts/code_size_ci\.py$|'
-    r'workflows/(cifuzz|claude|claude-code-review|code_size_windows|labeler|'
+    r'workflows/(cifuzz|claude|claude-code-review|labeler|'
     r'pr_comment|pre-commit|static_analysis|trigger)\.yml$)|'
     # tools/ scripts no build invokes (tools/build*.py and local tooling are handled separately)
     r'tools/(check_example_pids|file2carray|iar_gen|mksunxi|pcapng_to_corpus)\.py$|'

From e000182d7c0d5627901db2cd5f120fb2ea8979bf Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Mon, 5 Oct 2026 10:59:25 +0700
Subject: [PATCH 18/18] ci: drop the Windows code-size check from build-os

---
 .github/workflows/build.yml      |  1 -
 .github/workflows/build_util.yml | 26 --------------------------
 2 files changed, 27 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a05ec364fa..7d4a319c58 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -284,7 +284,6 @@ jobs:
       toolchain: 'arm-gcc-${{ matrix.os }}'
       build-args: '["stm32h7rs"]'
       build-options: '--one-random'
-      code-size-check: ${{ matrix.os == 'windows-latest' && matrix.build-system == 'cmake' && '-b stm32h7s3nucleo -e device/cdc_msc' || '' }}
 
   # ---------------------------------------
   # Zephyr
diff --git a/.github/workflows/build_util.yml b/.github/workflows/build_util.yml
index b42c51f02a..5dcf92c824 100644
--- a/.github/workflows/build_util.yml
+++ b/.github/workflows/build_util.yml
@@ -36,11 +36,6 @@ on:
         required: false
         default: true
         type: boolean
-      code-size-check:
-        description: 'code_size.py -b/-e args to check tools/code_size.py on this host with'
-        required: false
-        default: ''
-        type: string
 
 jobs:
   family:
@@ -122,27 +117,6 @@ jobs:
           fi
         shell: bash
 
-      - name: Code size check
-        # code_size.py on a host CI never snapshots on (build-os's Windows leg); its diffs
-        # rebuild twice more, so only a manual run takes them
-        if: inputs.code-size-check != ''
-        env:
-          PYTHONUTF8: '1'
-          CHECK: ${{ inputs.code-size-check }}
-          GH_TOKEN: ${{ github.token }}
-        run: |
-          python -m pip install --only-binary :all: membrowse==1.2.12 pyyaml pyelftools
-          (cd test/hil/test && python -m unittest -q test_code_size test_code_size_ci test_membrowse_cli)
-          python tools/code_size.py report $CHECK
-          if [ "$GITHUB_EVENT_NAME" = workflow_dispatch ]; then
-            git fetch -q --depth=1 origin master:refs/remotes/origin/master
-            python tools/code_size.py diff $CHECK --base-source local --base-branch HEAD --json
-            # diff passes a size change and some INCOMPLETE results; HEAD against HEAD must be neither
-            python -c "import glob, json; d = json.load(open(*glob.glob('cmake-code-size/*/diff_*.json'))); assert d['status'] == 'complete' and all(p['base']['files'] == p['current']['files'] for p in d['pairs']), d['status']"
-            python tools/code_size.py diff $CHECK --base-source ci --base-branch origin/master
-          fi
-        shell: bash
-
       - name: Code size snapshot
         id: code-size
         # measurement only: it also runs after a failed Build and records that in the