Each plugin gets a local committed copy of native_bridge/

The "shared src/native_bridge/ + per-plugin add_subdirectory('../../native_bridge')"
design ran into two unrelated platform constraints:
  - CocoaPods 1.16 silently rejects source_files whose resolved target lies
    outside the pod's enclosing directory.
  - Flutter on Windows symlinks plugins via NTFS junction points, which
    CMake's get_filename_component(REALPATH) and file(REAL_PATH) don't
    traverse — relative add_subdirectory paths land at non-existent
    .plugin_symlinks neighbors.

Two options were on the table. Sharing via cross-tree CMake references is
fragile and platform-specific; per-plugin local copies are boring but
robust. Go with per-plugin local copies — same model the darwin podspec
already uses (FileUtils.cp into Classes/).

Each platform plugin now ships its own native_bridge/ subdirectory and
its CMakeLists uses add_subdirectory("native_bridge") — purely local,
no path-traversal tricks. scripts/sync_native_bridge.sh copies from the
monorepo-canonical src/native_bridge/ into each plugin's local tree and
into darwin/Classes/. Run before commits when bridge C source changes.

`serious_python_bridge/python/setup.py` keeps its `NATIVE_ROOT = "../../native_bridge"`
since cibuildwheel only runs in the monorepo (where the canonical path
exists) and end users never invoke setup.py themselves.

Author: FeodorFitsner

scripts/sync_native_bridge.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+#
+# Sync the canonical bridge C sources at src/native_bridge/ into each
+# serious_python_bridge/<plat>/ plugin's local committed copy.
+#
+# Why each plugin owns a copy:
+#   - CocoaPods rejects symlinks/source_files that resolve outside the pod's
+#     enclosing directory. The darwin podspec works around this with a Ruby
+#     FileUtils.cp block (see darwin/serious_python_bridge.podspec), so the
+#     committed darwin/Classes/ files are kept in sync that way.
+#   - Flutter symlinks plugins into <example>/<plat>/flutter/ephemeral/
+#     .plugin_symlinks/. On Windows those are NTFS junction points which
+#     CMake's get_filename_component / file(REAL_PATH) don't traverse, so
+#     "../../native_bridge" lands at a non-existent neighbor path.
+#   - Result: each platform plugin's CMakeLists uses a LOCAL native_bridge/
+#     subdir as add_subdirectory target. We sync those local copies from
+#     the canonical src/native_bridge/ via this script.
+#
+# Run from anywhere; resolves to the repo root from $0's location.
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+ROOT="$PWD"
+SRC="$ROOT/src/native_bridge"
+
+if [ ! -d "$SRC" ]; then
+  echo "error: canonical source not found at $SRC" >&2
+  exit 1
+fi
+
+for plat in linux windows android; do
+  DEST="$ROOT/src/serious_python_bridge/$plat/native_bridge"
+  echo "[sync] $SRC -> $DEST"
+  rm -rf "$DEST"
+  mkdir -p "$DEST"
+  cp -R "$SRC/"* "$DEST/"
+done
+
+# Apple: copy directly into Classes/ (mirrors the FileUtils.cp logic in
+# darwin/serious_python_bridge.podspec; pre-populating means CI doesn't need
+# to invoke pod install just to refresh sources).
+DARWIN_DEST="$ROOT/src/serious_python_bridge/darwin/Classes"
+echo "[sync] $SRC -> $DARWIN_DEST"
+cp "$SRC/dart_bridge.c" "$DARWIN_DEST/"
+cp "$SRC/dart_bridge_shim.c" "$DARWIN_DEST/"
+rm -rf "$DARWIN_DEST/dart_api"
+cp -R "$SRC/dart_api" "$DARWIN_DEST/"
+
+echo "[sync] done. Diff against committed copies:"
+git -C "$ROOT" status --short src/serious_python_bridge/{linux,windows,android}/native_bridge src/serious_python_bridge/darwin/Classes/

src/serious_python_bridge/android/CMakeLists.txt

@@ -18,7 +18,10 @@ set(PYTHON_ABI_DIR "${PYTHON_DIST_DIR}/${ANDROID_ABI}")
 set(FLET_BRIDGE_PYTHON_INCLUDE_DIRS "${PYTHON_ABI_DIR}/include/python${PYTHON_VERSION}")
 set(FLET_BRIDGE_PYTHON_LIBRARIES "${PYTHON_ABI_DIR}/lib/libpython3.so")
 
-add_subdirectory("../../native_bridge" "${CMAKE_CURRENT_BINARY_DIR}/shared")
+# See note in linux/CMakeLists.txt — each platform plugin keeps its own
+# committed copy of native_bridge/, synced from src/native_bridge/ via
+# scripts/sync_native_bridge.sh.
+add_subdirectory("native_bridge" "${CMAKE_CURRENT_BINARY_DIR}/shared")
 
 # Android 15: 16 KB page size support.
 set_target_properties(flet_bridge PROPERTIES

src/serious_python_bridge/android/native_bridge/CMakeLists.txt

@@ -0,0 +1,67 @@
+# Cross-platform CMake target for libflet_bridge.
+#
+# Built from the same dart_bridge.c source used by the Python shim. Per-platform
+# wrappers under linux/, windows/, android/ include this file via add_subdirectory.
+#
+# Python integration:
+#   - If FLET_BRIDGE_PYTHON_INCLUDE_DIRS + FLET_BRIDGE_PYTHON_LIBRARIES are set
+#     before add_subdirectory, those are used (Android uses this path to point
+#     at the python-android-dart tarball it downloads).
+#   - Otherwise we use find_package(Python3 ... Development.Module) + the
+#     Python3::Module imported target, which handles Linux/macOS/Windows link
+#     conventions automatically.
+
+cmake_minimum_required(VERSION 3.15)
+
+project(flet_bridge VERSION 0.0.1 LANGUAGES C)
+
+if(NOT DEFINED FLET_BRIDGE_PYTHON_INCLUDE_DIRS)
+  find_package(Python3 REQUIRED COMPONENTS Development.Module)
+  set(FLET_BRIDGE_PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
+  if(WIN32)
+    # Python3::Module picks pythonXY.lib (or pythonXY_d.lib in Debug builds),
+    # but python-build-standalone for Windows doesn't ship a Debug variant
+    # so Flutter's debug builds fail with LNK1104. Link the abi3 stable-ABI
+    # stub python3.lib instead — it's version-agnostic AND has no debug
+    # variant requirement (matches our Py_LIMITED_API choice).
+    get_filename_component(_flet_bridge_python_root "${Python3_INCLUDE_DIRS}" DIRECTORY)
+    set(FLET_BRIDGE_PYTHON_LIBRARIES "${_flet_bridge_python_root}/libs/python3.lib")
+  else()
+    set(FLET_BRIDGE_PYTHON_LIBRARIES Python3::Module)
+  endif()
+endif()
+
+add_library(flet_bridge SHARED
+  "dart_bridge.c"
+  "dart_api/dart_api_dl.c"
+)
+
+target_include_directories(flet_bridge PRIVATE
+  "${CMAKE_CURRENT_SOURCE_DIR}"
+  ${FLET_BRIDGE_PYTHON_INCLUDE_DIRS}
+)
+
+target_link_libraries(flet_bridge PRIVATE ${FLET_BRIDGE_PYTHON_LIBRARIES})
+
+set_target_properties(flet_bridge PROPERTIES
+  C_VISIBILITY_PRESET hidden
+  OUTPUT_NAME "flet_bridge"
+)
+
+target_compile_definitions(flet_bridge PRIVATE DART_SHARED_LIB)
+
+if(WIN32)
+  # Python's pyconfig.h emits `#pragma comment(lib, "pythonXY_d.lib")` in
+  # Debug builds, which makes MSVC auto-link the Debug variant of libpython
+  # even though we explicitly linked python3.lib above. python-build-standalone
+  # doesn't ship a Debug lib, so the link fails (LNK1104). Py_NO_LINK_LIB
+  # suppresses the pragma in Python 3.14+, but 3.12 and 3.13 pyconfig.h don't
+  # honor it — use /NODEFAULTLIB:pythonXY_d.lib to explicitly exclude the
+  # Debug lib at link time. Works on every supported version.
+  target_compile_definitions(flet_bridge PRIVATE Py_NO_LINK_LIB)
+  if(Python3_VERSION_MAJOR AND Python3_VERSION_MINOR)
+    target_link_options(flet_bridge PRIVATE
+      "/NODEFAULTLIB:python${Python3_VERSION_MAJOR}${Python3_VERSION_MINOR}_d.lib"
+    )
+  endif()
+endif()