Add opt-in automatic connection for Switch 2 controllers

.github/workflows/native-switch2kit.yml

@@ -21,7 +21,9 @@ jobs:
           ref: f87239e71e42da91ca317a12eefb82cfbf3393eb
           path: test-sdl
           persist-credentials: false
-      - name: Execute mapping, identity, setup rollback and session regressions
+      - name: Install headers for production INI policy tests
+        run: sudo apt-get update && sudo apt-get install -y libboost-dev
+      - name: Execute mapping, identity, setup rollback, session and autoconnect regressions
         run: python3 tests/switch2kit/run.py --sdl test-sdl --sanitize
   macos:
     if: github.repository == 'jmonster/Cemu'

README.md

@@ -6,7 +6,7 @@ Use this controller-enabled Cemu directly: connect the controller, choose a play
 
 ## Quick start
 
-Sign in to GitHub and select a successful application run for `feature/switch2kit-desktop-platforms` while this PR is unmerged. Choose the named **application** artifact below and check its native build/launch jobs, not a source or diagnostics archive. These are expiring development builds, not published production releases. Use [Build from source](#build-from-source-alternative) when a matching application artifact is unavailable. Ordinary upstream downloads do not include this integration.
+Sign in to GitHub and select a successful application run for `feature/switch2kit-auto-connect` while this PR is unmerged. Choose the named **application** artifact below and check its native build/launch jobs, not a source or diagnostics archive. These are expiring development builds, not published production releases. Use [Build from source](#build-from-source-alternative) when a matching application artifact is unavailable. Ordinary upstream downloads do not include this integration.
 
 ### macOS
 
@@ -33,11 +33,13 @@ Keep its DLLs, `resources`, `gameProfiles` and `Switch2KitNotices` beside it. Th
 
 ### Connect and play
 
-1. Close competing controller apps/consoles. In Cemu, open **Options > Input settings**, click **Find Switch 2 Controllers**, and hold the controller's **Sync** button until its player lights sweep. Allow legitimate Bluetooth access prompts. The search lasts 60 seconds; repeat Find to retry.
+1. Close competing controller apps/consoles. In Cemu, open **Options > Input settings**, click **Find Switch 2 Controllers**, and hold the controller's **Sync** button until its player lights sweep. Allow legitimate Bluetooth access prompts. With automatic connection off, the search lasts 60 seconds; repeat Find to retry.
 2. Select the desired controller tab (for example, **Controller 1**). In the physical-controller dropdown beside **Emulated controller**, select the connected **GameCube** or **Pro Controller 2**. Cemu applies recommended mappings. An empty first slot becomes a Wii U GamePad, other empty slots become Wii U Pro Controllers; existing GamePad/Pro/Classic types are retained. Choose a type the game accepts.
 3. Verify buttons, sticks and triggers in Input settings. Open the physical controller's **Settings** to adjust **Rumble** and use **Test rumble**, then open the game. NSO GameCube trigger travel and full clicks remain independent inputs; Pro triggers are digital. GameCube sticks have no click buttons, so games needing those actions require additional bindings.
 
-Saved assignments follow the physical controller rather than its discovery order. Reopen the same application and use **Find** again on subsequent launches; Cemu does not implement Dolphin's automatic-reconnect option. **Disconnect Switch 2 Controllers** stops the backend without erasing saved profiles. Replacing a populated slot asks first and creates a **Before Switch2Kit-…** backup; reconnecting does not overwrite custom mappings.
+Saved assignments follow the physical controller rather than its discovery order. To connect on later launches and after long pauses without reopening Input settings, enable **Automatically connect Switch 2 controllers**. It is off by default and uses Bluetooth radio resources. Unchecking it stops automatic discovery without disconnecting ready controllers. With it off, use **Find** for a bounded search.
+
+**Disconnect Switch 2 Controllers** stops support for the current run without erasing profiles or the saved automatic-connection choice. Use **Find**, or turn the automatic option off and on, to resume deliberately; saved consent applies again on the next launch. Replacing a populated slot asks first and creates a **Before Switch2Kit-…** backup; reconnecting does not overwrite custom mappings. See [Automatic connection](docs/Switch2Kit.md#automatic-connection) for consent and troubleshooting details.
 
 For Joy-Con 2, discover each half with Find/Sync, choose the emulated controller type, and add both via **+ > SDLController** to the same player slot. These are separate complementary sources, not a system-wide paired virtual controller. Motion requires a measured, device-matching `.s2kmotion` profile selected in physical-controller Settings and **Use motion** enabled. Never use synthetic test profiles for gameplay. See [controller differences and motion](docs/Switch2Kit.md#controller-differences-and-motion).
 
@@ -46,7 +48,7 @@ For Joy-Con 2, discover each half with Find/Sync, choose the emulated controller
 Follow the [platform build guide](docs/Switch2Kit.md#build-from-source). Start from this implementation branch while the PR is unmerged:
 
 ```sh
-git clone --branch feature/switch2kit-desktop-platforms --recurse-submodules https://github.com/jmonster/Cemu.git cemu-switch2kit
+git clone --branch feature/switch2kit-auto-connect --recurse-submodules https://github.com/jmonster/Cemu.git cemu-switch2kit
 cd cemu-switch2kit
 ```
 
@@ -101,7 +103,7 @@ The old bug tracker can be found at [bugs.cemu.info](https://bugs.cemu.info) and
 
 ## Contributing
 
-If you want to contribute you can take a look at our [contribution guidelines](/CONTRIBUTING.md).
+To contribute, take a look at our [contribution guidelines](/CONTRIBUTING.md).
 
 ## License
 Cemu is licensed under [Mozilla Public License 2.0](/LICENSE.txt). Exempt from this are all files in the dependencies directory for which the licenses of the original code apply as well as some individual files in the src folder, as specified in those file headers respectively.

docs/Switch2Kit.md

@@ -6,7 +6,7 @@ Use the [controller-enabled downloads](../README.md#quick-start), launch that Ce
 
 ## Applications and prerequisites
 
-Sign in to GitHub and select a successful run for `feature/switch2kit-desktop-platforms` while this PR is unmerged. Download the application artifact, not a source or diagnostics archive. The outer GitHub artifact ZIP contains the application ZIP/tarball. Desktop application artifacts expire after 14 days; use the source fallback when no matching successful artifact remains. These are development builds, not published production releases. A workflow configuration or a different revision's result is not qualification of the selected download.
+Sign in to GitHub and select a successful run for `feature/switch2kit-auto-connect` while this PR is unmerged. Download the application artifact, not a source or diagnostics archive. The outer GitHub artifact ZIP contains the application ZIP/tarball. Desktop application artifacts expire after 14 days; use the source fallback when no matching successful artifact remains. These are development builds, not published production releases. A workflow configuration or a different revision's result is not qualification of the selected download.
 
 ### macOS
 
@@ -46,7 +46,8 @@ Enable **Settings > Bluetooth & devices > Bluetooth** and use Cemu's Find/Sync p
 
 Close any other app managing the same controllers. Open **Options > Input
 settings**, click **Find Switch 2 Controllers**, allow Bluetooth, and hold the
-controller's **Sync** button. Scanning lasts 60 seconds.
+controller's **Sync** button. With automatic connection off, scanning lasts
+60 seconds. Find opens another bounded window when needed.
 
 Choose the connected **GameCube** or **Pro Controller 2** in the new dropdown
 beside **Emulated controller** on the desired controller tab. Cemu applies the
@@ -65,8 +66,59 @@ reset custom mappings. A physical controller already assigned to another slot
 must be removed there before using the shortcut.
 
 Assignments persist by physical identity, including when identical controllers
-reconnect in a different order. Use **Find** again after restarting Cemu. Use
-**Disconnect Switch 2 Controllers** to stop this backend without erasing profiles.
+reconnect in a different order. Use **Find** again after restarting Cemu when
+automatic connection is off. Use **Disconnect Switch 2 Controllers** to stop this
+backend without erasing profiles.
+
+## Automatic connection
+
+Enable **Automatically connect Switch 2 controllers** in Input settings to start
+support on future launches and keep discovery available after long controller
+absences or paused gameplay. It is **off by default**. Cemu saves this consent
+before applying the radio policy. Startup happens once on the GUI main run loop
+after SDL initialization, even when Input settings is never opened, on every
+platform with this native backend enabled.
+
+This uses the SDK's continuous discovery policy, not a timer repeatedly calling
+Find or renewing a 60-second window. While Cemu remains open, supported advertising
+controllers can be discovered when Bluetooth and connection capacity permit. It
+uses radio resources and is **not a remembered-device allowlist**. It does not
+pair arbitrary Bluetooth devices, wake a powered-off controller, grant permission,
+assign a player slot, or reapply mappings. Initial pairing still requires Sync
+and permission; turn the controller on to reconnect thereafter.
+
+Unchecking the option returns discovery to on-demand mode without detaching
+ready controllers. An already admitted connection attempt may finish. To cancel
+attempts and disconnect all native controllers, use **Disconnect** instead.
+Disconnect is authoritative for the current run: input polling, reopening
+settings, resuming a game, and a delayed startup callback cannot restart support.
+Use **Find**, or turn the option off and on, to resume deliberately. The saved
+choice is retained for the next application launch. After Disconnect, the SDK's
+asynchronous stop may briefly report busy; retry explicitly after it finishes.
+
+The preference is `[Settings] AutoConnect=true` or `false` in `Switch2Kit.ini`,
+beside Cemu's `settings.xml`, not inside controller profiles. Missing files/keys
+mean off. Updates re-read the file, preserve unrelated entries and sections, and
+use Cemu's atomic writer. INI comments/formatting are not preserved. Malformed,
+oversized, inaccessible or non-regular files are not silently replaced. A save
+that would exceed the 64 KiB read limit is rejected before writing, so a successful
+save remains readable on the next launch. A failed save leaves the previous
+choice and radio policy intact; the checkbox reflects the saved choice. Repair
+file access or malformed configuration and retry the option. Configuration and
+policy/start errors remain visible through successful polling and status
+refreshes. Find retries starting support, not saving settings.
+
+The SDK submodule is pinned to
+`d9129e3876f0d68aa7d13395dcff8e2abb38d609`, which combines the shared `SDLHost`
+automatic-discovery and policy-only start methods from
+[Switch2Kit PR #74](https://github.com/jmonster/Switch2Kit/pull/74) with the merged
+[desktop transport and runtime fixes](https://github.com/jmonster/Switch2Kit/pull/75).
+Do not substitute the older automatic-connection pin, which lacks those desktop
+fixes, or a library missing `s2k_set_automatic_discovery`. Source-integration
+checks verify the matching pin. Both SDK changes are merged; this permanent
+commit has the same source tree as the previously reviewed SDK revision. This
+application's own current-revision native checks remain required; earlier
+separate branch results do not qualify the combined application.
 
 ## Controller differences and motion
 
@@ -107,7 +159,7 @@ backend does not invent sensor values or integrate across a disconnect or gap.
 `ENABLE_SWITCH2KIT` is OFF by default. Disabled builds do not require Swift and retain upstream platform/deployment requirements. Enabled Linux/Windows builds use native SDL3 and the desktop backend; only enabled macOS builds require a macOS 15+ app bundle. Initialize the SDK revision selected by this maintained fork, not a moving SDK branch or the SDK's separate upstream patches. While the PR is unmerged:
 
 ```sh
-git clone --branch feature/switch2kit-desktop-platforms --recurse-submodules https://github.com/jmonster/Cemu.git cemu-switch2kit
+git clone --branch feature/switch2kit-auto-connect --recurse-submodules https://github.com/jmonster/Cemu.git cemu-switch2kit
 cd cemu-switch2kit
 ```
 
@@ -141,10 +193,45 @@ For updates, quit Cemu, run `git pull --ff-only`, update the recorded submodules
 
 ## Qualification and troubleshooting
 
-A missing **Find Switch 2 Controllers** button means a backend-disabled binary was launched. For absent input, verify Bluetooth power/access, Sync mode, competing connections, physical selection and the emulated type accepted by the game, then retry Find. A controller already assigned to another slot must be removed there before the quick setup shortcut can move it. Cemu requires Find again after restarting; it does not implement Dolphin's automatic-reconnection option. A changed adapter or rotating device address can change physical identity, so verify player assignments after such a change.
+A missing **Find Switch 2 Controllers** button means a backend-disabled binary was launched. For absent input, verify Bluetooth power/access, Sync mode, competing connections, physical selection and the emulated type accepted by the game, then retry Find. A controller already assigned to another slot must be removed there before the quick setup shortcut can move it. Cemu requires Find again after restarting when automatic connection is off; with it enabled, saved consent starts continuous discovery on the next launch. A changed adapter or rotating device address can change physical identity, so verify player assignments after such a change.
 
 Desktop CI builds the complete application, archives it, extracts that exact archive into a new location, checks that the GUI loads its packaged controller/Swift libraries, requests normal quit and relaunches with a private profile. It deliberately seeds noninteractive test settings; pristine first-use dialogs, downloaded-app security approval and physical hardware are not tested. No existing user configuration is erased. The artifact is qualified only after these jobs pass for its exact revision.
 
-`python3 tests/switch2kit/run.py --sanitize` retains executable mapping, identity, lifecycle and rollback regressions against controlled host/storage boundaries. `python3 tests/switch2kit/test_host_file.py --sdk dependencies/Switch2Kit --sanitize` exercises the real bounded file reader; native MSVC coverage is retained. SDK tests cover protocol values, real C/SDL consumers, calibrated sample handling, rumble bounds, cancellation, runtime relocation and required notices. Source-contract checks supplement those tests, not prose length or English wording restrictions.
+`python3 tests/switch2kit/run.py --sanitize` retains executable mapping, identity, lifecycle, rollback, automatic-connection and configuration regressions against controlled host/storage boundaries. Use `--sdl /path/to/SDL-source` and `--sdk /path/to/Switch2Kit` for a separate checkout of the same pinned SDK revision. `python3 tests/switch2kit/test_host_file.py --sdk dependencies/Switch2Kit --sanitize` exercises the real bounded file reader; native MSVC coverage is retained. SDK tests cover protocol values, real C/SDL consumers, calibrated sample handling, rumble bounds, cancellation, runtime relocation and required notices. Source-contract checks supplement those tests, not prose length or English wording restrictions.
+
+The standalone automatic-connection suite needs a C++20 compiler and Boost headers:
+
+```sh
+python3 tests/switch2kit/test_autoconnect.py --sanitize
+CXX=g++ python3 tests/switch2kit/test_autoconnect.py --sanitize
+```
+
+These tests execute the production session/configuration policies with controlled
+SDK-host and atomic-writer boundaries and real INI file reads. They cover default
+off, one-shot consent, polling without renewal, stop/shutdown fences, live-session
+preservation, save/read failure, retry and unrelated INI entries. Size regressions
+verify exact-limit round trips and preservation of both the file and runtime choice
+when an update would exceed the input bound. Source checks guard the startup hook,
+checkbox, SDK pin and native/backend-disabled gates; they are not GUI or physical
+Bluetooth execution. The desktop lifecycle and Debug/Release adapter CRT configure
+regressions remain in the same runner.
+
+### Automatic-connection hardware acceptance
+
+1. With a fresh configuration, verify automatic connection is off. Enable it,
+   pair a controller, close Input settings, and relaunch Cemu without opening
+   settings. Verify input, releases, sticks and rumble remain usable.
+2. Power off a controller for longer than 60 seconds, then turn it on. Repeat
+   several cycles with a game paused and with settings closed. Also test
+   Bluetooth off/on and recovery after permission is granted.
+3. Reconnect two controllers in reverse order and verify saved player identity,
+   custom mappings and motion-profile selection do not change.
+4. Disable automatic connection while playing: existing input should remain.
+   After disconnecting the controller, use Find for manual discovery.
+5. Use Disconnect with automatic connection enabled, then wake controllers,
+   reopen settings and resume gameplay. Support must remain stopped until Find,
+   explicit re-enabling, or a later launch with saved consent.
+6. Check unreadable/malformed settings and failed saves on a real installation:
+   the checkbox and error status must accurately report the retained choice.
 
 Record separate hardware acceptance for each model/firmware/OS/adapter and tested commit: first pairing and denied-access retry; all controls and releases; independent GameCube trigger travel/clicks; rumble start/stop; two identical controllers reconnecting in reversed order; persisted player assignments after restart; Bluetooth/adapter loss; explicit disconnect; normal shutdown; measured motion where used; and an actual gameplay session. Joy-Con 2 acceptance must include both complementary sources in one slot. No fixture profile or automated pass substitutes for those physical results.