Nicer structure

AGENTS.md

@@ -4,7 +4,7 @@
 A pure GTK4 C++ GUI for remapping the G1–G9 keys of a Logitech G910. Today it
 only edits and persists mappings: there is **no** hardware G-key detection and
 **no** command execution yet (a native daemon is the planned next step). The
-whole program is one translation unit, `src/main.cpp`.
+code is split into a few small translation units under `src/` (see below).
 
 ## Build / run / verify
 - `make` — builds the `gkeymapper` binary **and** the `.mo` catalogs.
@@ -30,10 +30,16 @@ whole program is one translation unit, `src/main.cpp`.
   `po/de.po`.
 
 ## Code layout and conventions
-- `src/main.cpp` holds everything in an anonymous namespace. The global `rows`
-  vector keeps one `KeyRow` (widget pointers) per G key. `on_activate` registers
-  the app actions `app.export-config`, `app.import-config`, `app.about`;
-  `build_ui` constructs the window. App id: `com.example.gkeymapper`.
+- Modules under `src/` (shared API lives in `namespace gkeymapper`):
+  `keyrow.h` (`KeyRow`, `kNumKeys`), `mappings.{h,cpp}` (config file I/O),
+  `capturedialog.{h,cpp}` (key-capture dialog), `main.cpp` (app actions + UI).
+- The Makefile globs sources (`$(wildcard src/*.cpp)`): a new `.cpp` is compiled
+  automatically, and `src/*.h` are prerequisites of the target.
+- `main.cpp` keeps the `rows` vector (one `KeyRow` per G key, widget pointers)
+  in an anonymous namespace; mappings functions receive it as a parameter.
+  `on_activate` registers the app actions `app.export-config`,
+  `app.import-config`, `app.about`; `build_ui` constructs the window. App id:
+  `com.example.gkeymapper`.
 - The Type dropdown index is meaningful everywhere: `0=Key`, `1=Command`,
   `2=Disabled`. Keep that order — import/export map against it.
 - The capture dialog's `CaptureSession` is heap-allocated and freed only by the