Add a Steam Frame build option; no chaperone commit at start; timer-based tick

- CMake option OVRAS_STEAM_FRAME. It is evaluated only in
  src/utils/platform_capabilities.h, which turns it into named capability
  constants and platform defaults.
- Where the chaperone can't be committed (Steam Frame: it shifts the play
  area), MoveCenterTabController no longer commits the working copy at start-up
  or when applying reset data, and doesn't create the init autosave profile.
  Skips are logged once.
- In "vsync disabled" mode the pump timer now runs directly at the custom tick
  rate instead of firing every 1 ms and counting. The Frame defaults to this
  mode at 11 ms (~90 Hz).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CMakeLists.txt

@@ -111,6 +111,7 @@ set(HEADERS
     src/utils/paths.h
     src/utils/setup.h
     src/utils/update_rate.h
+    src/utils/platform_capabilities.h
     src/utils/Matrix.h
     src/quaternion/quaternion.h
     )
@@ -290,6 +291,14 @@ target_compile_definitions(AdvancedSettings PRIVATE
     APPLICATION_VERSION=\"${PROJECT_VERSION}\"
 )
 
+# Build for the Steam Frame (SteamOS, aarch64). Switches off what doesn't work
+# there and changes some defaults; the details are named capability constants
+# in src/utils/platform_capabilities.h, the only place reading this definition.
+option(OVRAS_STEAM_FRAME "Build for the Steam Frame" OFF)
+if (OVRAS_STEAM_FRAME)
+    target_compile_definitions(AdvancedSettings PRIVATE OVRAS_STEAM_FRAME=1)
+endif ()
+
 #find_library(OPENVR_LIBRARIES
 #    NAMES
 #      openvr_api

docs/steamframe/PROGRESS.md

@@ -26,3 +26,34 @@
 - `libopenvr_api.so` is resolved from the binary's directory (`ldd`).
 - Not started: without a running SteamVR the start hangs in OpenVR init (expected; tested
   on the Frame in step 5).
+
+### Step 2: platform option, R7, tick (2026-10-07)
+
+**Changes:**
+- **Platform option:**
+  - CMake option `OVRAS_STEAM_FRAME` (default OFF) sets the compile definition
+    `OVRAS_STEAM_FRAME=1`.
+  - New `src/utils/platform_capabilities.h` evaluates it as the only place. It holds
+    `k_chaperoneCommitSupported`, `k_defaultVsyncDisabled` and `k_defaultCustomTickRateMs`.
+- **Tick (R6):**
+  - In "vsync disabled" mode, `m_pumpEventsTimer` runs directly at `customTickRateMs`
+    (`applyTickInterval()`, `Qt::PreciseTimer`); the 1 ms counting is gone.
+  - Changing the setting restarts the timer.
+  - Setting defaults in `settings_controller.h` come from the constants: Frame `true`/11 ms,
+    otherwise unchanged `false`/20 ms.
+- **R7:** with `!k_chaperoneCommitSupported`:
+  - `updateChaperoneResetData()` and `applyChaperoneResetData()` skip
+    `CommitWorkingCopy`/`RevertWorkingCopy`. Each logs once per function.
+  - The init autosave profile is skipped.
+
+**Results:**
+- Both variants (default and `-DOVRAS_STEAM_FRAME=ON`) build on x86_64. The definition is
+  only set in the Frame variant (`compile_commands.json`).
+- Not tested at runtime yet (Frame, step 5).
+
+**Notes:**
+- Another commit at start-up remains, but only on opt-in. `SetWidget()` applies a chaperone
+  profile and commits when "auto-apply chaperone" (`autoApplyChaperoneToggle`, default
+  `false`) is on. That's a chaperone-profile feature, so it belongs to R5 (iteration 2).
+- clang-format reflows comment blocks next to new comments. Separate new comments from
+  existing commented-out code with a blank line, otherwise the diff grows.

src/overlaycontroller.cpp

@@ -480,9 +480,7 @@ void OverlayController::SetWidget( QQuickItem* quickItem,
              this,
              SLOT( OnTimeoutPumpEvents() ) );
 
-    // Every 1ms we check if the current frame has advanced (for vsync)
+    applyTickInterval();
-    m_pumpEventsTimer.setInterval( 1 );
-
     m_pumpEventsTimer.start();
 
     m_steamVRTabController.initStage2( this );
@@ -966,6 +964,8 @@ void OverlayController::setVsyncDisabled( bool value, bool notify )
 {
     settings::setSetting( settings::BoolSetting::APPLICATION_vsyncDisabled,
                           value );
+    // The timer interval depends on the mode, see applyTickInterval().
+    applyTickInterval();
     if ( notify )
     {
         emit vsyncDisabledChanged( value );
@@ -1076,6 +1076,8 @@ void OverlayController::setCustomTickRateMs( int value, bool notify )
     settings::setSetting( settings::IntSetting::APPLICATION_customTickRateMs,
                           verifiedTickRate );
     m_verifiedCustomTickRateMs = verifiedTickRate;
+    // In "vsync disabled" mode the timer runs at this interval.
+    applyTickInterval();
 
     if ( notify )
     {
@@ -1083,6 +1085,19 @@ void OverlayController::setCustomTickRateMs( int value, bool notify )
     }
 }
 
+// Sets the interval of m_pumpEventsTimer for the current tick mode:
+// - vsync: every 1 ms, OnTimeoutPumpEvents() checks whether the compositor
+//   started a new frame.
+// - vsync disabled: the timer fires directly at the custom tick rate, so the
+//   process wakes up once per tick instead of every 1 ms.
+// QTimer::setInterval() also restarts a running timer with the new interval.
+void OverlayController::applyTickInterval()
+{
+    m_pumpEventsTimer.setTimerType( Qt::PreciseTimer );
+    m_pumpEventsTimer.setInterval( vsyncDisabled() ? customTickRateMs() : 1 );
+}
+
+// Called by m_pumpEventsTimer, see applyTickInterval().
 // vsync implementation:
 // this function triggers every 1ms
 // this function should remain lightweight and only check if it's time to
@@ -1091,17 +1106,10 @@ void OverlayController::OnTimeoutPumpEvents()
 {
     if ( vsyncDisabled() )
     {
-        // check if it's time for a custom tick rate tick
+        // The timer already runs at the custom tick rate: every call is a
-        if ( m_customTickRateCounter > customTickRateMs() )
+        // tick.
-        {
+        mainEventLoop();
-            mainEventLoop();
+        updateRate.incrementCounter();
-            m_customTickRateCounter = 0;
-            updateRate.incrementCounter();
-        }
-        else
-        {
-            m_customTickRateCounter++;
-        }
     }
 
     // vsync is enabled

src/overlaycontroller.h

@@ -158,7 +158,6 @@ private:
     uint64_t m_currentFrame = 0;
     uint64_t m_lastFrame = 0;
     int m_vsyncTooLateCounter = 0;
-    int m_customTickRateCounter = 0;
     int m_verifiedCustomTickRateMs = 0;
 
     input::SteamIVRInput m_actions;
@@ -200,6 +199,8 @@ private:
         return m_renderControl.rhi();
     }
 
+    void applyTickInterval();
+
     bool m_exclusiveState = false;
     bool m_keyPressOneState = false;
     bool m_keyPressTwoState = false;

src/settings/internal/settings_controller.h

@@ -9,6 +9,7 @@
 #include "../../utils/setup.h"
 #include "specific_setting_value.h"
 #include "../../tabcontrollers/MoveCenterTabController.h"
+#include "../../utils/platform_capabilities.h"
 
 namespace settings
 {
@@ -303,10 +304,11 @@ private:
                           SettingCategory::Application,
                           QtInfo{ "previousShutdownSafe" },
                           true },
+        // Default depends on the platform (fixed-interval tick on the Frame).
         BoolSettingValue{ BoolSetting::APPLICATION_vsyncDisabled,
                           SettingCategory::Application,
                           QtInfo{ "vsyncDisabled" },
-                          false },
+                          platform::k_defaultVsyncDisabled },
         BoolSettingValue{ BoolSetting::APPLICATION_crashRecoveryDisabled,
                           SettingCategory::Application,
                           QtInfo{ "crashRecoveryDisabled" },
@@ -610,10 +612,11 @@ private:
                          SettingCategory::Application,
                          QtInfo{ "debugState" },
                          0 },
+        // Default depends on the platform (about 90 Hz on the Frame).
         IntSettingValue{ IntSetting::APPLICATION_customTickRateMs,
                          SettingCategory::Application,
                          QtInfo{ "customTickRateMs" },
-                         20 },
+                         platform::k_defaultCustomTickRateMs },
 
         IntSettingValue{ IntSetting::UTILITY_alarmHour,
                          SettingCategory::Utility,

src/tabcontrollers/MoveCenterTabController.cpp

@@ -1,10 +1,13 @@
 #include "MoveCenterTabController.h"
 #include <QQuickWindow>
+#include <set>
+#include <string>
 #include <QtLogging>
 #include <QtDebug>
 #include "../overlaycontroller.h"
 #include "../quaternion/quaternion.h"
 #include "../settings/settings.h"
+#include "../utils/platform_capabilities.h"
 
 void rotateCoordinates( double coordinates[3], double angle )
 {
@@ -1106,7 +1109,13 @@ void MoveCenterTabController::zeroOffsets()
                 if ( calState != 200 )
                 {
                     // all init complete, safe to autosave chaperone profile
-                    parent->m_chaperoneTabController.createNewAutosaveProfile();
+                    // Not where the chaperone can't be committed: the autosave
+                    // exists to restore a committed play area later.
+                    if ( platform::k_chaperoneCommitSupported )
+                    {
+                        parent->m_chaperoneTabController
+                            .createNewAutosaveProfile();
+                    }
                     m_initComplete = true;
                     m_chaperoneBasisAcquired = true;
                     qInfo() << "Chaperone Initilization Complete, Space Drag "
@@ -1172,6 +1181,19 @@ void MoveCenterTabController::clampVelocity( double* velocity )
     }
 }
 
+// Logs once per caller that a chaperone commit was skipped, so the log shows
+// it without repeating it every tick.
+static void logSkippedChaperoneCommit( const char* caller )
+{
+    static std::set<std::string> logged;
+    if ( logged.insert( caller ).second )
+    {
+        qInfo() << caller
+                << ": CommitWorkingCopy skipped, not supported on this "
+                   "platform (logged once)";
+    }
+}
+
 void MoveCenterTabController::updateChaperoneResetData()
 {
     //auto cstate = vr::VRChaperone()->GetCalibrationState();
@@ -1183,9 +1205,20 @@ void MoveCenterTabController::updateChaperoneResetData()
     // }
     // else
     //{
+
+    // Committing writes the working copy as the live play area. Where that
+    // isn't supported (it shifts the play area on the Steam Frame), only the
+    // working copy is read below.
+    if ( platform::k_chaperoneCommitSupported )
+    {
         vr::VRChaperoneSetup()->CommitWorkingCopy(
             vr::EChaperoneConfigFile_Live );
         vr::VRChaperoneSetup()->RevertWorkingCopy();
+    }
+    else
+    {
+        logSkippedChaperoneCommit( "updateChaperoneResetData" );
+    }
     //}
     unsigned currentQuadCount = 0;
     vr::VRChaperoneSetup()->GetWorkingCollisionBoundsInfo( nullptr,
@@ -1228,7 +1261,16 @@ void MoveCenterTabController::applyChaperoneResetData()
     //  vr::VRChaperoneSetup()->SetWorkingSeatedZeroPoseToRawTrackingPose(
     //     &m_seatedCenterForReset );
 
-    vr::VRChaperoneSetup()->CommitWorkingCopy( vr::EChaperoneConfigFile_Live );
+    // See updateChaperoneResetData(): no commit where it isn't supported.
+    if ( platform::k_chaperoneCommitSupported )
+    {
+        vr::VRChaperoneSetup()->CommitWorkingCopy(
+            vr::EChaperoneConfigFile_Live );
+    }
+    else
+    {
+        logSkippedChaperoneCommit( "applyChaperoneResetData" );
+    }
 
     unsigned checkQuadCount = 0;
     vr::VRChaperoneSetup()->GetWorkingCollisionBoundsInfo( nullptr,

src/utils/platform_capabilities.h

@@ -0,0 +1,28 @@
+#pragma once
+
+// What the target platform supports, and platform-specific defaults.
+//
+// This is the only place that evaluates the build option OVRAS_STEAM_FRAME
+// (CMake option of the same name). All other code asks for the named constants
+// below, never for the platform, so it stays clear *why* something differs.
+// See docs/steamframe/DESIGN.md, section 7.
+
+#ifndef OVRAS_STEAM_FRAME
+#    define OVRAS_STEAM_FRAME 0
+#endif
+
+namespace platform
+{
+// IVRChaperoneSetup::CommitWorkingCopy() writes the working copy as the live
+// chaperone. OVRAS does this at start-up and when applying offsets. On the
+// Steam Frame (inside-out tracking) it shifts the play area, so it must not
+// happen there.
+constexpr bool k_chaperoneCommitSupported = !OVRAS_STEAM_FRAME;
+
+// Default tick: by default OVRAS polls every 1 ms for a new compositor frame
+// ("vsync"). The Frame defaults to a fixed-interval tick instead, which wakes
+// the process about 11 times less often. 11 ms is about 90 Hz, the frame rate
+// OVRAS's tick-counted intervals were designed for.
+constexpr bool k_defaultVsyncDisabled = OVRAS_STEAM_FRAME;
+constexpr int k_defaultCustomTickRateMs = OVRAS_STEAM_FRAME ? 11 : 20;
+} // namespace platform