docs(ipm): canonicalize README.md to English (from README_en.md)

app/ipm/README.md

@@ -36,6 +36,45 @@ Best practices
 
 For French documentation see: [README_fr.md](README_fr.md)
 
+````
+````markdown
+# IPM native integration (app.ipm)
+
+This folder contains the Python wrapper that calls the native refifc libraries.
+
+Goals
+- Centralize the Python wrapper under `app/ipm` so application code can import `app.ipm.simple_refrig_api`.
+- Provide a clear location for native binaries (DLLs for Windows, .so for Linux).
+
+Where to place native binaries
+- Windows (local/dev): place DLL files in `app/ipm/lib/windows/`.
+- Linux (container/production): place .so files in `app/ipm/lib/linux/`.
+
+The wrapper `app/ipm/simple_refrig_api.py` will look first in `app/ipm/lib/<platform>` (`windows` or `linux`) and fall back to the package directory if nothing is found.
+
+Do NOT commit native binaries
+--------------------------------
+Native binaries should not be committed to the repo (size, licensing, portability). The repo contains a `.gitignore` rule excluding `app/ipm/lib/windows/*.dll` and `app/ipm/lib/linux/*.so`.
+
+CI/CD
+- Store binaries in a secure artifact repository (releases, internal storage, S3, etc.).
+- During CI, download them and copy into `app/ipm/lib/<platform>` before building the image or deploying.
+
+Quick local test
+1. Copy the binaries into the correct folder (e.g. `app/ipm/lib/windows/refifc.dll`).
+2. Test locally:
+
+```powershell
+.venv\Scripts\python -c "import app.ipm.simple_refrig_api as s; r=s.Refifc('R290'); print('hsl_px exists', hasattr(r,'hsl_px'))"
+```
+
+Best practices
+- Avoid committing binaries in Git.
+- Record the exact origin and version of native binaries in release notes.
+- Provide small helper scripts (`scripts/copy-ipm-libs.*`) to automate copying binaries into build environments.
+
+For French documentation see: [README_fr.md](README_fr.md)
+
 ````
 # IPM native integration (app.ipm) — English (default)