Own Linux platform services and narrow legacy fallback

docs/modernization/debt.md

@@ -18,6 +18,12 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Reductions
 
+- 2026-06-17: `DEBT-0016`/`DEBT-0017`/`DEBT-0051` were narrowed again.
+  `src/platform_linux/linux_platform_services.*` now owns the concrete Linux
+  `PlatformServices` implementation and `linux/src/main.cpp` now binds that
+  owned service directly, so `src/platform_legacy/legacy_platform_services.*`
+  no longer carries the touched Linux storage-path, GLFW render-context,
+  app-close, desktop picker, default-render-target, or FPS-reporting branches.
 - 2026-06-17: `DEBT-0016`/`DEBT-0017` were narrowed again.
   `src/platform_android/android_platform_services.*` now owns the concrete
   Android `PlatformServices` implementation and

docs/modernization/roadmap.md

@@ -70,6 +70,19 @@ What is already real:
 - `pp_app_core`
 
 Latest slice:
+- `src/platform_linux/linux_platform_services.*` now owns the concrete Linux
+  `PlatformServices` implementation and `create_platform_services(...)`
+  instead of leaving the live Linux execution surface inside
+  `platform_legacy`.
+- `linux/src/main.cpp` now binds that owned Linux `PlatformServices` instance
+  into `App` directly at the Linux entrypoint.
+- The touched Linux storage-path setup, GLFW render-context acquire/present,
+  app-close dispatch, default render-target binding, desktop file picking, and
+  FPS reporting now route through `src/platform_linux/linux_platform_services.*`
+  instead of the cross-platform fallback adapter.
+- `src/platform_legacy/legacy_platform_services.*` no longer carries the
+  touched Linux method branches, so the retained fallback adapter is narrower
+  again and now focused on the Web path plus generic fallback policy.
 - `src/platform_android/android_platform_services.*` now owns the concrete
   Android `PlatformServices` implementation and `create_platform_services()`
   instead of leaving the live Android execution surface inside
@@ -82,8 +95,7 @@ Latest slice:
   cross-platform fallback adapter.
 - `src/platform_legacy/legacy_platform_services.*` no longer carries the
   Android bridge/configuration surface or the touched Android method branches,
-  so the retained fallback adapter is narrower again and now focused on the
-  Linux/Web path plus generic fallback policy.
+  so the retained fallback adapter was narrowed again before the Linux cut.
 - `src/platform_apple/apple_platform_services.*` now owns the concrete Apple
   `PlatformServices` implementation plus the `create_apple_platform_services()`
   factory instead of leaving the live Apple execution surface inside

docs/modernization/tasks.md

@@ -52,8 +52,10 @@ Completed, blocked, and superseded task history moved to
     `src/platform_apple/apple_platform_services.*`, and the live Apple
     `PlatformServices` surface now binds directly from those Apple-owned files,
     and Android now also binds directly from
-    `src/platform_android/android_platform_services.*`, but the broader
-    non-Windows fallback adapter still exists for Linux/Web
+    `src/platform_android/android_platform_services.*`, and Linux now also
+    binds directly from `src/platform_linux/linux_platform_services.*`, but the
+    broader non-Windows fallback adapter still exists for Web plus generic
+    fallback policy
   - `platform_legacy` is still part of the live app shell
 - The app runtime boundary is not finished:
   - render/UI queues are static `App` state
@@ -81,6 +83,18 @@ Completed, blocked, and superseded task history moved to
   the queue is now ordered by code movement instead.
 
 Current slice:
+- `src/platform_linux/linux_platform_services.*` now owns the concrete Linux
+  `PlatformServices` implementation and `create_platform_services(...)`
+  instead of leaving the live Linux execution surface in `platform_legacy`.
+- `linux/src/main.cpp` now binds that owned Linux `PlatformServices` instance
+  into `App` directly at the Linux entrypoint.
+- The touched Linux storage-path setup, GLFW render-context acquire/present,
+  app-close dispatch, default render-target binding, desktop file picking, and
+  FPS reporting now route through `src/platform_linux/linux_platform_services.*`
+  instead of the cross-platform fallback adapter.
+- `src/platform_legacy/legacy_platform_services.*` no longer carries the
+  touched Linux method branches, so the retained fallback adapter is narrower
+  again and now focused on the Web path plus generic fallback policy.
 - `src/platform_android/android_platform_services.*` now owns the concrete
   Android `PlatformServices` implementation and `create_platform_services()`
   instead of leaving the live Android execution surface in
@@ -93,8 +107,7 @@ Current slice:
   cross-platform fallback adapter.
 - `src/platform_legacy/legacy_platform_services.*` no longer carries the
   Android bridge/configuration surface or the touched Android method branches,
-  so the retained fallback adapter is narrower again and now focused on the
-  Linux/Web path plus generic fallback policy.
+  so the retained fallback adapter was narrowed again before the Linux cut.
 - `src/platform_apple/apple_platform_services.*` now owns the concrete Apple
   `PlatformServices` implementation plus the `create_apple_platform_services()`
   factory instead of leaving the live Apple execution surface in