diff --git a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
index 58c6628..224dad1 100644
--- a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
+++ b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
@@ -111,11 +111,15 @@
 
     MOCK_CONST_METHOD1(dump, void(std::string&));
     MOCK_CONST_METHOD0(getComposer, android::Hwc2::Composer*());
-    MOCK_CONST_METHOD1(getHwcDisplayId, std::optional<hal::HWDisplayId>(int32_t));
-    MOCK_CONST_METHOD0(getInternalHwcDisplayId, std::optional<hal::HWDisplayId>());
-    MOCK_CONST_METHOD0(getExternalHwcDisplayId, std::optional<hal::HWDisplayId>());
-    MOCK_CONST_METHOD1(toPhysicalDisplayId, std::optional<PhysicalDisplayId>(hal::HWDisplayId));
-    MOCK_CONST_METHOD1(fromPhysicalDisplayId, std::optional<hal::HWDisplayId>(PhysicalDisplayId));
+
+    MOCK_METHOD(hal::HWDisplayId, getPrimaryHwcDisplayId, (), (const, override));
+    MOCK_METHOD(PhysicalDisplayId, getPrimaryDisplayId, (), (const, override));
+    MOCK_METHOD(bool, isHeadless, (), (const, override));
+
+    MOCK_METHOD(std::optional<PhysicalDisplayId>, toPhysicalDisplayId, (hal::HWDisplayId),
+                (const, override));
+    MOCK_METHOD(std::optional<hal::HWDisplayId>, fromPhysicalDisplayId, (PhysicalDisplayId),
+                (const, override));
 };
 
 } // namespace mock
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index afd12b5..7db87d9 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -273,7 +273,7 @@
 
     std::atomic<nsecs_t> mLastHwVsync = 0;
 
-    // TODO(b/74619554): Remove special cases for primary display.
+    // TODO(b/182939859): Remove special cases for primary display.
     const bool mIsPrimary;
 
     uint32_t mFlags = 0;
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index a790b4c..b0443f7 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -212,8 +212,6 @@
     RETURN_IF_INVALID_DISPLAY(*displayId, false);
 
     auto& displayData = mDisplayData[*displayId];
-    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
-                 __FUNCTION__, to_string(*displayId).c_str());
 
     {
         // There have been reports of HWCs that signal several vsync events
@@ -271,7 +269,6 @@
     display->setConnected(true);
     auto& displayData = mDisplayData[displayId];
     displayData.hwcDisplay = std::move(display);
-    displayData.isVirtual = true;
     return true;
 }
 
@@ -279,10 +276,8 @@
                                          PhysicalDisplayId displayId) {
     mPhysicalDisplayIdMap[hwcDisplayId] = displayId;
 
-    if (!mInternalHwcDisplayId) {
-        mInternalHwcDisplayId = hwcDisplayId;
-    } else if (mInternalHwcDisplayId != hwcDisplayId && !mExternalHwcDisplayId) {
-        mExternalHwcDisplayId = hwcDisplayId;
+    if (!mPrimaryHwcDisplayId) {
+        mPrimaryHwcDisplayId = hwcDisplayId;
     }
 
     auto& displayData = mDisplayData[displayId];
@@ -372,7 +367,7 @@
     ui::DisplayConnectionType type;
     const auto error = hwcDisplay->getConnectionType(&type);
 
-    const auto FALLBACK_TYPE = hwcDisplay->getId() == mInternalHwcDisplayId
+    const auto FALLBACK_TYPE = hwcDisplay->getId() == mPrimaryHwcDisplayId
             ? ui::DisplayConnectionType::Internal
             : ui::DisplayConnectionType::External;
 
@@ -428,9 +423,6 @@
     RETURN_IF_INVALID_DISPLAY(displayId);
     auto& displayData = mDisplayData[displayId];
 
-    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
-                 __FUNCTION__, to_string(displayId).c_str());
-
     // NOTE: we use our own internal lock here because we have to call
     // into the HWC with the lock held, and we want to make sure
     // that even if HWC blocks (which it shouldn't), it won't
@@ -597,14 +589,11 @@
 status_t HWComposer::setPowerMode(PhysicalDisplayId displayId, hal::PowerMode mode) {
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
 
-    const auto& displayData = mDisplayData[displayId];
-    LOG_FATAL_IF(displayData.isVirtual, "%s: Invalid operation on virtual display with ID %s",
-                 __FUNCTION__, to_string(displayId).c_str());
-
     if (mode == hal::PowerMode::OFF) {
         setVsyncEnabled(displayId, hal::Vsync::DISABLE);
     }
 
+    const auto& displayData = mDisplayData[displayId];
     auto& hwcDisplay = displayData.hwcDisplay;
     switch (mode) {
         case hal::PowerMode::OFF:
@@ -677,13 +666,8 @@
     RETURN_IF_INVALID_DISPLAY(displayId);
     auto& displayData = mDisplayData[displayId];
     const auto hwcDisplayId = displayData.hwcDisplay->getId();
+    LOG_ALWAYS_FATAL_IF(hwcDisplayId == mPrimaryHwcDisplayId);
 
-    // TODO(b/74619554): Select internal/external display from remaining displays.
-    if (hwcDisplayId == mInternalHwcDisplayId) {
-        mInternalHwcDisplayId.reset();
-    } else if (hwcDisplayId == mExternalHwcDisplayId) {
-        mExternalHwcDisplayId.reset();
-    }
     mPhysicalDisplayIdMap.erase(hwcDisplayId);
     mDisplayData.erase(displayId);
 }
@@ -693,9 +677,6 @@
     RETURN_IF_INVALID_DISPLAY(displayId, BAD_INDEX);
     const auto& displayData = mDisplayData[displayId];
 
-    LOG_FATAL_IF(!displayData.isVirtual, "%s: Invalid operation on physical display with ID %s",
-                 __FUNCTION__, to_string(displayId).c_str());
-
     auto error = displayData.hwcDisplay->setOutputBuffer(buffer, acquireFence);
     RETURN_IF_HWC_ERROR(error, displayId, UNKNOWN_ERROR);
     return NO_ERROR;
@@ -853,8 +834,7 @@
 
 std::optional<hal::HWDisplayId> HWComposer::fromPhysicalDisplayId(
         PhysicalDisplayId displayId) const {
-    if (const auto it = mDisplayData.find(displayId);
-        it != mDisplayData.end() && !it->second.isVirtual) {
+    if (const auto it = mDisplayData.find(displayId); it != mDisplayData.end()) {
         return it->second.hwcDisplay->getId();
     }
     return {};
@@ -868,7 +848,8 @@
         return true;
     }
 
-    if (!mHasMultiDisplaySupport && mInternalHwcDisplayId && mExternalHwcDisplayId) {
+    // Legacy mode only supports IDs LEGACY_DISPLAY_TYPE_PRIMARY and LEGACY_DISPLAY_TYPE_EXTERNAL.
+    if (!mHasMultiDisplaySupport && mPhysicalDisplayIdMap.size() == 2) {
         ALOGE("Ignoring connection of tertiary display %" PRIu64, hwcDisplayId);
         return true;
     }
@@ -909,7 +890,7 @@
         }
 
         info = [this, hwcDisplayId, &port, &data, hasDisplayIdentificationData] {
-            const bool isPrimary = !mInternalHwcDisplayId;
+            const bool isPrimary = !mPrimaryHwcDisplayId;
             if (mHasMultiDisplaySupport) {
                 if (const auto info = parseDisplayIdentificationData(port, data)) {
                     return *info;
@@ -922,8 +903,8 @@
             }
 
             return DisplayIdentificationInfo{.id = PhysicalDisplayId::fromPort(port),
-                                             .name = isPrimary ? "Internal display"
-                                                               : "External display",
+                                             .name = isPrimary ? "Primary display"
+                                                               : "Secondary display",
                                              .deviceProductInfo = std::nullopt};
         }();
     }
@@ -936,9 +917,12 @@
 
 std::optional<DisplayIdentificationInfo> HWComposer::onHotplugDisconnect(
         hal::HWDisplayId hwcDisplayId) {
+    LOG_ALWAYS_FATAL_IF(hwcDisplayId == mPrimaryHwcDisplayId,
+                        "Primary display cannot be disconnected.");
+
     const auto displayId = toPhysicalDisplayId(hwcDisplayId);
     if (!displayId) {
-        ALOGE("Ignoring disconnection of invalid HWC display %" PRIu64, hwcDisplayId);
+        LOG_HWC_DISPLAY_ERROR(hwcDisplayId, "Invalid HWC display");
         return {};
     }
 
@@ -947,7 +931,7 @@
     if (isConnected(*displayId)) {
         mDisplayData[*displayId].hwcDisplay->setConnected(false);
     } else {
-        ALOGW("Attempted to disconnect unknown display %" PRIu64, hwcDisplayId);
+        LOG_HWC_DISPLAY_ERROR(hwcDisplayId, "Already disconnected");
     }
     // The cleanup of Disconnect is handled through HWComposer::disconnectDisplay
     // via SurfaceFlinger's onHotplugReceived callback handling
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index 49f96d9..0a090da 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_SF_HWCOMPOSER_H
-#define ANDROID_SF_HWCOMPOSER_H
+#pragma once
 
 #include <cstdint>
 #include <future>
@@ -228,14 +227,18 @@
     virtual const std::unordered_map<std::string, bool>& getSupportedLayerGenericMetadata()
             const = 0;
 
-    // for debugging ----------------------------------------------------------
     virtual void dump(std::string& out) const = 0;
 
     virtual Hwc2::Composer* getComposer() const = 0;
 
-    // TODO(b/74619554): Remove special cases for internal/external display.
-    virtual std::optional<hal::HWDisplayId> getInternalHwcDisplayId() const = 0;
-    virtual std::optional<hal::HWDisplayId> getExternalHwcDisplayId() const = 0;
+    // Returns the first display connected at boot. It cannot be disconnected, which implies an
+    // internal connection type. Its connection via HWComposer::onHotplug, which in practice is
+    // immediately after HWComposer construction, must occur before any call to this function.
+    //
+    // TODO(b/182939859): Remove special cases for primary display.
+    virtual hal::HWDisplayId getPrimaryHwcDisplayId() const = 0;
+    virtual PhysicalDisplayId getPrimaryDisplayId() const = 0;
+    virtual bool isHeadless() const = 0;
 
     virtual std::optional<PhysicalDisplayId> toPhysicalDisplayId(hal::HWDisplayId) const = 0;
     virtual std::optional<hal::HWDisplayId> fromPhysicalDisplayId(PhysicalDisplayId) const = 0;
@@ -366,14 +369,19 @@
 
     Hwc2::Composer* getComposer() const override { return mComposer.get(); }
 
-    // TODO(b/74619554): Remove special cases for internal/external display.
-    std::optional<hal::HWDisplayId> getInternalHwcDisplayId() const override {
-        return mInternalHwcDisplayId;
+    hal::HWDisplayId getPrimaryHwcDisplayId() const override {
+        LOG_ALWAYS_FATAL_IF(!mPrimaryHwcDisplayId, "Missing HWC primary display");
+        return *mPrimaryHwcDisplayId;
     }
-    std::optional<hal::HWDisplayId> getExternalHwcDisplayId() const override {
-        return mExternalHwcDisplayId;
+
+    PhysicalDisplayId getPrimaryDisplayId() const override {
+        const auto id = toPhysicalDisplayId(getPrimaryHwcDisplayId());
+        LOG_ALWAYS_FATAL_IF(!id, "Missing primary display");
+        return *id;
     }
 
+    virtual bool isHeadless() const override { return !mPrimaryHwcDisplayId; }
+
     std::optional<PhysicalDisplayId> toPhysicalDisplayId(hal::HWDisplayId) const override;
     std::optional<hal::HWDisplayId> fromPhysicalDisplayId(PhysicalDisplayId) const override;
 
@@ -382,12 +390,9 @@
     friend TestableSurfaceFlinger;
 
     struct DisplayData {
-        bool isVirtual = false;
         std::unique_ptr<HWC2::Display> hwcDisplay;
         sp<Fence> lastPresentFence = Fence::NO_FENCE; // signals when the last set op retires
         std::unordered_map<HWC2::Layer*, sp<Fence>> releaseFences;
-        buffer_handle_t outbufHandle = nullptr;
-        sp<Fence> outbufAcquireFence = Fence::NO_FENCE;
 
         bool validateWasSkipped;
         hal::Error presentError;
@@ -418,8 +423,7 @@
     bool mRegisteredCallback = false;
 
     std::unordered_map<hal::HWDisplayId, PhysicalDisplayId> mPhysicalDisplayIdMap;
-    std::optional<hal::HWDisplayId> mInternalHwcDisplayId;
-    std::optional<hal::HWDisplayId> mExternalHwcDisplayId;
+    std::optional<hal::HWDisplayId> mPrimaryHwcDisplayId;
     bool mHasMultiDisplaySupport = false;
 
     const size_t mMaxVirtualDisplayDimension;
@@ -428,5 +432,3 @@
 
 } // namespace impl
 } // namespace android
-
-#endif // ANDROID_SF_HWCOMPOSER_H
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 294a67e..e306152 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -633,17 +633,14 @@
 }
 
 std::vector<PhysicalDisplayId> SurfaceFlinger::getPhysicalDisplayIdsLocked() const {
-    const auto internalDisplayId = getInternalDisplayIdLocked();
-    if (!internalDisplayId) {
-        return {};
-    }
-
     std::vector<PhysicalDisplayId> displayIds;
     displayIds.reserve(mPhysicalDisplayTokens.size());
-    displayIds.push_back(*internalDisplayId);
+
+    const auto internalDisplayId = getInternalDisplayIdLocked();
+    displayIds.push_back(internalDisplayId);
 
     for (const auto& [id, token] : mPhysicalDisplayTokens) {
-        if (id != *internalDisplayId) {
+        if (id != internalDisplayId) {
             displayIds.push_back(id);
         }
     }
@@ -810,10 +807,10 @@
     // Process any initial hotplug and resulting display changes.
     processDisplayHotplugEventsLocked();
     const auto display = getDefaultDisplayDeviceLocked();
-    LOG_ALWAYS_FATAL_IF(!display, "Missing internal display after registering composer callback.");
+    LOG_ALWAYS_FATAL_IF(!display, "Missing primary display after registering composer callback.");
     const auto displayId = display->getPhysicalId();
     LOG_ALWAYS_FATAL_IF(!getHwComposer().isConnected(displayId),
-                        "Internal display is disconnected.");
+                        "Primary display is disconnected.");
 
     // initialize our drawing state
     mDrawingState = mCurrentState;
@@ -982,6 +979,11 @@
         return NAME_NOT_FOUND;
     }
 
+    const auto displayId = PhysicalDisplayId::tryCast(display->getId());
+    if (!displayId) {
+        return INVALID_OPERATION;
+    }
+
     info->activeDisplayModeId = static_cast<int32_t>(display->getActiveMode()->getId().value());
 
     const auto& supportedModes = display->getSupportedModes();
@@ -1041,18 +1043,18 @@
     }
 
     info->activeColorMode = display->getCompositionDisplay()->getState().colorMode;
-    const auto displayId = display->getPhysicalId();
-    info->supportedColorModes = getDisplayColorModes(displayId);
-
+    info->supportedColorModes = getDisplayColorModes(*display);
     info->hdrCapabilities = display->getHdrCapabilities();
+
     info->autoLowLatencyModeSupported =
-            getHwComposer().hasDisplayCapability(displayId,
+            getHwComposer().hasDisplayCapability(*displayId,
                                                  hal::DisplayCapability::AUTO_LOW_LATENCY_MODE);
     std::vector<hal::ContentType> types;
-    getHwComposer().getSupportedContentTypes(displayId, &types);
+    getHwComposer().getSupportedContentTypes(*displayId, &types);
     info->gameContentTypeSupported = std::any_of(types.begin(), types.end(), [](auto type) {
         return type == hal::ContentType::GAME;
     });
+
     return NO_ERROR;
 }
 
@@ -1276,15 +1278,15 @@
     }).wait();
 }
 
-std::vector<ColorMode> SurfaceFlinger::getDisplayColorModes(PhysicalDisplayId displayId) {
-    auto modes = getHwComposer().getColorModes(displayId);
-    bool isInternalDisplay = displayId == getInternalDisplayIdLocked();
+std::vector<ColorMode> SurfaceFlinger::getDisplayColorModes(const DisplayDevice& display) {
+    auto modes = getHwComposer().getColorModes(display.getPhysicalId());
 
-    // If it's built-in display and the configuration claims it's not wide color capable,
+    // If the display is internal and the configuration claims it's not wide color capable,
     // filter out all wide color modes. The typical reason why this happens is that the
     // hardware is not good enough to support GPU composition of wide color, and thus the
     // OEMs choose to disable this capability.
-    if (isInternalDisplay && !hasWideColorDisplay) {
+    if (display.getConnectionType() == ui::DisplayConnectionType::Internal &&
+        !hasWideColorDisplay) {
         const auto newEnd = std::remove_if(modes.begin(), modes.end(), isWideColorMode);
         modes.erase(newEnd, modes.end());
     }
@@ -1308,35 +1310,40 @@
 }
 
 status_t SurfaceFlinger::setActiveColorMode(const sp<IBinder>& displayToken, ColorMode mode) {
-    schedule([=]() MAIN_THREAD {
-        const auto displayId = getPhysicalDisplayIdLocked(displayToken);
-        if (!displayId) {
-            ALOGE("Invalid display token %p", displayToken.get());
-            return;
-        }
-        const auto modes = getDisplayColorModes(*displayId);
-        bool exists = std::find(std::begin(modes), std::end(modes), mode) != std::end(modes);
-        if (mode < ColorMode::NATIVE || !exists) {
-            ALOGE("Attempt to set invalid active color mode %s (%d) for display token %p",
-                  decodeColorMode(mode).c_str(), mode, displayToken.get());
-            return;
-        }
+    if (!displayToken) {
+        return BAD_VALUE;
+    }
+
+    auto future = schedule([=]() MAIN_THREAD -> status_t {
         const auto display = getDisplayDeviceLocked(displayToken);
         if (!display) {
             ALOGE("Attempt to set active color mode %s (%d) for invalid display token %p",
                   decodeColorMode(mode).c_str(), mode, displayToken.get());
-        } else if (display->isVirtual()) {
+            return NAME_NOT_FOUND;
+        }
+
+        if (display->isVirtual()) {
             ALOGW("Attempt to set active color mode %s (%d) for virtual display",
                   decodeColorMode(mode).c_str(), mode);
-        } else {
-            display->getCompositionDisplay()->setColorProfile(
-                    compositionengine::Output::ColorProfile{mode, Dataspace::UNKNOWN,
-                                                            RenderIntent::COLORIMETRIC,
-                                                            Dataspace::UNKNOWN});
+            return INVALID_OPERATION;
         }
-    }).wait();
 
-    return NO_ERROR;
+        const auto modes = getDisplayColorModes(*display);
+        const bool exists = std::find(modes.begin(), modes.end(), mode) != modes.end();
+
+        if (mode < ColorMode::NATIVE || !exists) {
+            ALOGE("Attempt to set invalid active color mode %s (%d) for display token %p",
+                  decodeColorMode(mode).c_str(), mode, displayToken.get());
+            return BAD_VALUE;
+        }
+
+        display->getCompositionDisplay()->setColorProfile(
+                {mode, Dataspace::UNKNOWN, RenderIntent::COLORIMETRIC, Dataspace::UNKNOWN});
+
+        return NO_ERROR;
+    });
+
+    return future.get();
 }
 
 void SurfaceFlinger::setAutoLowLatencyMode(const sp<IBinder>& displayToken, bool on) {
@@ -1749,8 +1756,8 @@
 
 void SurfaceFlinger::onComposerHalHotplug(hal::HWDisplayId hwcDisplayId,
                                           hal::Connection connection) {
-    ALOGI("%s(%" PRIu64 ", %s)", __func__, hwcDisplayId,
-          connection == hal::Connection::CONNECTED ? "connected" : "disconnected");
+    const bool connected = connection == hal::Connection::CONNECTED;
+    ALOGI("%s HAL display %" PRIu64, connected ? "Connecting" : "Disconnecting", hwcDisplayId);
 
     // Only lock if we're not on the main thread. This function is normally
     // called on a hwbinder thread, but for the primary display it's called on
@@ -1942,13 +1949,9 @@
     }
 
     if (mRefreshRateOverlaySpinner) {
-        if (Mutex::Autolock lock(mStateLock);
-            const auto display = getDefaultDisplayDeviceLocked()) {
-            if (display) {
-                display->onInvalidate();
-            } else {
-                ALOGW("%s: default display is null", __func__);
-            }
+        Mutex::Autolock lock(mStateLock);
+        if (const auto display = getDefaultDisplayDeviceLocked()) {
+            display->onInvalidate();
         }
     }
 
@@ -2842,7 +2845,7 @@
             setPowerModeInternal(display, hal::PowerMode::ON);
 
             // TODO(b/175678251) Call a listener instead.
-            if (currentState.physical->hwcDisplayId == getHwComposer().getInternalHwcDisplayId()) {
+            if (currentState.physical->hwcDisplayId == getHwComposer().getPrimaryHwcDisplayId()) {
                 updateInternalDisplayVsyncLocked(display);
             }
         }
@@ -5687,12 +5690,10 @@
             // Inject a hotplug connected event for the primary display. This will deallocate and
             // reallocate the display state including framebuffers.
             case 1037: {
-                std::optional<hal::HWDisplayId> hwcId;
-                {
-                    Mutex::Autolock lock(mStateLock);
-                    hwcId = getHwComposer().getInternalHwcDisplayId();
-                }
-                onComposerHalHotplug(*hwcId, hal::Connection::CONNECTED);
+                const hal::HWDisplayId hwcId =
+                        (Mutex::Autolock(mStateLock), getHwComposer().getPrimaryHwcDisplayId());
+
+                onComposerHalHotplug(hwcId, hal::Connection::CONNECTED);
                 return NO_ERROR;
             }
             // Modify the max number of display frames stored within FrameTimeline
@@ -6774,33 +6775,29 @@
 }
 
 status_t SurfaceFlinger::getMaxAcquiredBufferCount(int* buffers) const {
-    const auto maxSupportedRefreshRate = [&] {
-        const auto display = getDefaultDisplayDevice();
-        if (display) {
-            return display->refreshRateConfigs().getSupportedRefreshRateRange().max;
+    Fps maxRefreshRate(60.f);
+
+    if (!getHwComposer().isHeadless()) {
+        if (const auto display = getDefaultDisplayDevice()) {
+            maxRefreshRate = display->refreshRateConfigs().getSupportedRefreshRateRange().max;
         }
-        ALOGW("%s: default display is null", __func__);
-        return Fps(60);
-    }();
-    *buffers = getMaxAcquiredBufferCountForRefreshRate(maxSupportedRefreshRate);
+    }
+
+    *buffers = getMaxAcquiredBufferCountForRefreshRate(maxRefreshRate);
     return NO_ERROR;
 }
 
 int SurfaceFlinger::getMaxAcquiredBufferCountForCurrentRefreshRate(uid_t uid) const {
-    const auto refreshRate = [&] {
-        const auto frameRateOverride = mScheduler->getFrameRateOverride(uid);
-        if (frameRateOverride.has_value()) {
-            return frameRateOverride.value();
-        }
+    Fps refreshRate(60.f);
 
-        const auto display = ON_MAIN_THREAD(getDefaultDisplayDeviceLocked());
-        if (display) {
-            return display->refreshRateConfigs().getCurrentRefreshRate().getFps();
+    if (const auto frameRateOverride = mScheduler->getFrameRateOverride(uid)) {
+        refreshRate = *frameRateOverride;
+    } else if (!getHwComposer().isHeadless()) {
+        if (const auto display = ON_MAIN_THREAD(getDefaultDisplayDeviceLocked())) {
+            refreshRate = display->refreshRateConfigs().getCurrentRefreshRate().getFps();
         }
+    }
 
-        ALOGW("%s: default display is null", __func__);
-        return Fps(60);
-    }();
     return getMaxAcquiredBufferCountForRefreshRate(refreshRate);
 }
 
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 241d319..7a66aca 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1113,15 +1113,19 @@
         return {};
     }
 
-    // TODO(b/74619554): Remove special cases for primary display.
+    // TODO(b/182939859): SF conflates the primary (a.k.a. default) display with the first display
+    // connected at boot, which is typically internal. (Theoretically, it must be internal because
+    // SF does not support disconnecting it, though in practice HWC may circumvent this limitation.)
+    //
+    // SF inherits getInternalDisplayToken and getInternalDisplayId from ISurfaceComposer, so these
+    // locked counterparts are named consistently. Once SF supports headless mode and can designate
+    // any display as primary, the "internal" misnomer will be phased out.
     sp<IBinder> getInternalDisplayTokenLocked() const REQUIRES(mStateLock) {
-        const auto displayId = getInternalDisplayIdLocked();
-        return displayId ? getPhysicalDisplayTokenLocked(*displayId) : nullptr;
+        return getPhysicalDisplayTokenLocked(getInternalDisplayIdLocked());
     }
 
-    std::optional<PhysicalDisplayId> getInternalDisplayIdLocked() const REQUIRES(mStateLock) {
-        const auto hwcDisplayId = getHwComposer().getInternalHwcDisplayId();
-        return hwcDisplayId ? getHwComposer().toPhysicalDisplayId(*hwcDisplayId) : std::nullopt;
+    PhysicalDisplayId getInternalDisplayIdLocked() const REQUIRES(mStateLock) {
+        return getHwComposer().getPrimaryDisplayId();
     }
 
     // Toggles use of HAL/GPU virtual displays.
@@ -1200,8 +1204,7 @@
     /*
      * Misc
      */
-    std::vector<ui::ColorMode> getDisplayColorModes(PhysicalDisplayId displayId)
-            REQUIRES(mStateLock);
+    std::vector<ui::ColorMode> getDisplayColorModes(const DisplayDevice&) REQUIRES(mStateLock);
 
     static int calculateMaxAcquiredBufferCount(Fps refreshRate,
                                                std::chrono::nanoseconds presentLatency);
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
index b713334..313ab03 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_HandleTransactionLockedTest.cpp
@@ -282,7 +282,8 @@
 }
 
 TEST_F(HandleTransactionLockedTest, processesHotplugDisconnectPrimaryDisplay) {
-    processesHotplugDisconnectCommon<SimplePrimaryDisplayCase>();
+    EXPECT_EXIT(processesHotplugDisconnectCommon<SimplePrimaryDisplayCase>(),
+                testing::KilledBySignal(SIGABRT), "Primary display cannot be disconnected.");
 }
 
 TEST_F(HandleTransactionLockedTest, processesHotplugDisconnectExternalDisplay) {
@@ -290,96 +291,106 @@
 }
 
 TEST_F(HandleTransactionLockedTest, processesHotplugConnectThenDisconnectPrimary) {
-    using Case = SimplePrimaryDisplayCase;
+    EXPECT_EXIT(
+            [this] {
+                using Case = SimplePrimaryDisplayCase;
 
-    // --------------------------------------------------------------------
-    // Preconditions
+                // --------------------------------------------------------------------
+                // Preconditions
 
-    setupCommonPreconditions<Case>();
+                setupCommonPreconditions<Case>();
 
-    // A hotplug connect event is enqueued for a display
-    Case::Display::injectPendingHotplugEvent(this, Connection::CONNECTED);
-    // A hotplug disconnect event is also enqueued for the same display
-    Case::Display::injectPendingHotplugEvent(this, Connection::DISCONNECTED);
+                // A hotplug connect event is enqueued for a display
+                Case::Display::injectPendingHotplugEvent(this, Connection::CONNECTED);
+                // A hotplug disconnect event is also enqueued for the same display
+                Case::Display::injectPendingHotplugEvent(this, Connection::DISCONNECTED);
 
-    // --------------------------------------------------------------------
-    // Call Expectations
+                // --------------------------------------------------------------------
+                // Call Expectations
 
-    setupCommonCallExpectationsForConnectProcessing<Case>();
-    setupCommonCallExpectationsForDisconnectProcessing<Case>();
+                setupCommonCallExpectationsForConnectProcessing<Case>();
+                setupCommonCallExpectationsForDisconnectProcessing<Case>();
 
-    EXPECT_CALL(*mComposer,
-                setVsyncEnabled(Case::Display::HWC_DISPLAY_ID, IComposerClient::Vsync::DISABLE))
-            .WillOnce(Return(Error::NONE));
-    EXPECT_CALL(*mConsumer, consumerDisconnect()).WillOnce(Return(NO_ERROR));
+                EXPECT_CALL(*mComposer,
+                            setVsyncEnabled(Case::Display::HWC_DISPLAY_ID,
+                                            IComposerClient::Vsync::DISABLE))
+                        .WillOnce(Return(Error::NONE));
+                EXPECT_CALL(*mConsumer, consumerDisconnect()).WillOnce(Return(NO_ERROR));
 
-    // --------------------------------------------------------------------
-    // Invocation
+                // --------------------------------------------------------------------
+                // Invocation
 
-    mFlinger.handleTransactionLocked(eDisplayTransactionNeeded);
+                mFlinger.handleTransactionLocked(eDisplayTransactionNeeded);
 
-    // --------------------------------------------------------------------
-    // Postconditions
+                // --------------------------------------------------------------------
+                // Postconditions
 
-    // HWComposer should not have an entry for the display
-    EXPECT_FALSE(hasPhysicalHwcDisplay(Case::Display::HWC_DISPLAY_ID));
+                // HWComposer should not have an entry for the display
+                EXPECT_FALSE(hasPhysicalHwcDisplay(Case::Display::HWC_DISPLAY_ID));
 
-    // SF should not have a display token.
-    const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 0);
+                // SF should not have a display token.
+                const auto displayId = Case::Display::DISPLAY_ID::get();
+                ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+                ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 0);
+            }(),
+            testing::KilledBySignal(SIGABRT), "Primary display cannot be disconnected.");
 }
 
 TEST_F(HandleTransactionLockedTest, processesHotplugDisconnectThenConnectPrimary) {
-    using Case = SimplePrimaryDisplayCase;
+    EXPECT_EXIT(
+            [this] {
+                using Case = SimplePrimaryDisplayCase;
 
-    // --------------------------------------------------------------------
-    // Preconditions
+                // --------------------------------------------------------------------
+                // Preconditions
 
-    setupCommonPreconditions<Case>();
+                setupCommonPreconditions<Case>();
 
-    // The display is already completely set up.
-    Case::Display::injectHwcDisplay(this);
-    auto existing = Case::Display::makeFakeExistingDisplayInjector(this);
-    existing.inject();
+                // The display is already completely set up.
+                Case::Display::injectHwcDisplay(this);
+                auto existing = Case::Display::makeFakeExistingDisplayInjector(this);
+                existing.inject();
 
-    // A hotplug disconnect event is enqueued for a display
-    Case::Display::injectPendingHotplugEvent(this, Connection::DISCONNECTED);
-    // A hotplug connect event is also enqueued for the same display
-    Case::Display::injectPendingHotplugEvent(this, Connection::CONNECTED);
+                // A hotplug disconnect event is enqueued for a display
+                Case::Display::injectPendingHotplugEvent(this, Connection::DISCONNECTED);
+                // A hotplug connect event is also enqueued for the same display
+                Case::Display::injectPendingHotplugEvent(this, Connection::CONNECTED);
 
-    // --------------------------------------------------------------------
-    // Call Expectations
+                // --------------------------------------------------------------------
+                // Call Expectations
 
-    setupCommonCallExpectationsForConnectProcessing<Case>();
-    setupCommonCallExpectationsForDisconnectProcessing<Case>();
+                setupCommonCallExpectationsForConnectProcessing<Case>();
+                setupCommonCallExpectationsForDisconnectProcessing<Case>();
 
-    // --------------------------------------------------------------------
-    // Invocation
+                // --------------------------------------------------------------------
+                // Invocation
 
-    mFlinger.handleTransactionLocked(eDisplayTransactionNeeded);
+                mFlinger.handleTransactionLocked(eDisplayTransactionNeeded);
 
-    // --------------------------------------------------------------------
-    // Postconditions
+                // --------------------------------------------------------------------
+                // Postconditions
 
-    // The existing token should have been removed
-    verifyDisplayIsNotConnected(existing.token());
-    const auto displayId = Case::Display::DISPLAY_ID::get();
-    ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
-    ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 1);
-    EXPECT_NE(existing.token(), mFlinger.mutablePhysicalDisplayTokens()[displayId]);
+                // The existing token should have been removed
+                verifyDisplayIsNotConnected(existing.token());
+                const auto displayId = Case::Display::DISPLAY_ID::get();
+                ASSERT_TRUE(PhysicalDisplayId::tryCast(displayId));
+                ASSERT_TRUE(mFlinger.mutablePhysicalDisplayTokens().count(displayId) == 1);
+                EXPECT_NE(existing.token(), mFlinger.mutablePhysicalDisplayTokens()[displayId]);
 
-    // A new display should be connected in its place
+                // A new display should be connected in its place
 
-    verifyPhysicalDisplayIsConnected<Case>();
+                verifyPhysicalDisplayIsConnected<Case>();
 
-    // --------------------------------------------------------------------
-    // Cleanup conditions
+                // --------------------------------------------------------------------
+                // Cleanup conditions
 
-    EXPECT_CALL(*mComposer,
-                setVsyncEnabled(Case::Display::HWC_DISPLAY_ID, IComposerClient::Vsync::DISABLE))
-            .WillOnce(Return(Error::NONE));
-    EXPECT_CALL(*mConsumer, consumerDisconnect()).WillOnce(Return(NO_ERROR));
+                EXPECT_CALL(*mComposer,
+                            setVsyncEnabled(Case::Display::HWC_DISPLAY_ID,
+                                            IComposerClient::Vsync::DISABLE))
+                        .WillOnce(Return(Error::NONE));
+                EXPECT_CALL(*mConsumer, consumerDisconnect()).WillOnce(Return(NO_ERROR));
+            }(),
+            testing::KilledBySignal(SIGABRT), "Primary display cannot be disconnected.");
 }
 
 TEST_F(HandleTransactionLockedTest, processesVirtualDisplayAdded) {
diff --git a/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetupNewDisplayDeviceInternalTest.cpp b/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetupNewDisplayDeviceInternalTest.cpp
index e32c4bf..7ead0af 100644
--- a/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetupNewDisplayDeviceInternalTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SurfaceFlinger_SetupNewDisplayDeviceInternalTest.cpp
@@ -292,7 +292,9 @@
 }
 
 TEST_F(SetupNewDisplayDeviceInternalTest, createSimpleExternalDisplay) {
-    setupNewDisplayDeviceInternalTest<SimpleExternalDisplayCase>();
+    // External displays must be secondary, as the primary display cannot be disconnected.
+    EXPECT_EXIT(setupNewDisplayDeviceInternalTest<SimpleExternalDisplayCase>(),
+                testing::KilledBySignal(SIGABRT), "Missing primary display");
 }
 
 TEST_F(SetupNewDisplayDeviceInternalTest, createNonHwcVirtualDisplay) {
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 56ae414..e036f4d 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -439,8 +439,7 @@
 
     auto& mutableHwcDisplayData() { return getHwComposer().mDisplayData; }
     auto& mutableHwcPhysicalDisplayIdMap() { return getHwComposer().mPhysicalDisplayIdMap; }
-    auto& mutableInternalHwcDisplayId() { return getHwComposer().mInternalHwcDisplayId; }
-    auto& mutableExternalHwcDisplayId() { return getHwComposer().mExternalHwcDisplayId; }
+    auto& mutablePrimaryHwcDisplayId() { return getHwComposer().mPrimaryHwcDisplayId; }
     auto& mutableUseFrameRateApi() { return mFlinger->useFrameRateApi; }
 
     auto fromHandle(const sp<IBinder>& handle) {
@@ -600,13 +599,12 @@
                 LOG_ALWAYS_FATAL_IF(!physicalId);
                 flinger->mutableHwcPhysicalDisplayIdMap().emplace(mHwcDisplayId, *physicalId);
                 if (mIsPrimary) {
-                    flinger->mutableInternalHwcDisplayId() = mHwcDisplayId;
+                    flinger->mutablePrimaryHwcDisplayId() = mHwcDisplayId;
                 } else {
-                    // If there is an external HWC display there should always be an internal ID
+                    // If there is an external HWC display, there should always be a primary ID
                     // as well. Set it to some arbitrary value.
-                    auto& internalId = flinger->mutableInternalHwcDisplayId();
-                    if (!internalId) internalId = mHwcDisplayId - 1;
-                    flinger->mutableExternalHwcDisplayId() = mHwcDisplayId;
+                    auto& primaryId = flinger->mutablePrimaryHwcDisplayId();
+                    if (!primaryId) primaryId = mHwcDisplayId - 1;
                 }
             }
         }