22 files changed, 86 insertions, 72 deletions
diff --git a/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h b/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
index 5c6258d0..9a5fb8f8 100644
--- a/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
+++ b/src/api/burn/WixToolset.BootstrapperCore.Native/inc/BootstrapperApplication.h
@@ -642,7 +642,7 @@ struct BA_ONCOMMITMSITRANSACTIONCOMPLETE_RESULTS
 struct BA_ONDETECTBEGIN_ARGS
 {
    DWORD cbSize;
-    BOOL fInstalled;
+    BOOTSTRAPPER_REGISTRATION_TYPE registrationType;
    DWORD cPackages;
    BOOL fCached;
 };
diff --git a/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs b/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
index b08e66c0..1df992be 100644
--- a/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
+++ b/src/api/burn/WixToolset.Mba.Core/BootstrapperApplication.cs
@@ -1378,9 +1378,9 @@ namespace WixToolset.Mba.Core
            return args.HResult;
        }
-        int IBootstrapperApplication.OnDetectBegin(bool fCached, bool fInstalled, int cPackages, ref bool fCancel)
+        int IBootstrapperApplication.OnDetectBegin(bool fCached, RegistrationType registrationType, int cPackages, ref bool fCancel)
        {
-            DetectBeginEventArgs args = new DetectBeginEventArgs(fCached, fInstalled, cPackages, fCancel);
+            DetectBeginEventArgs args = new DetectBeginEventArgs(fCached, registrationType, cPackages, fCancel);
            this.OnDetectBegin(args);
            fCancel = args.Cancel;
diff --git a/src/api/burn/WixToolset.Mba.Core/EventArgs.cs b/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
index 2e1e1be3..816757cc 100644
--- a/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
+++ b/src/api/burn/WixToolset.Mba.Core/EventArgs.cs
@@ -249,11 +249,11 @@ namespace WixToolset.Mba.Core
    public class DetectBeginEventArgs : CancellableHResultEventArgs
    {
        /// <summary />
-        public DetectBeginEventArgs(bool cached, bool installed, int packageCount, bool cancelRecommendation)
+        public DetectBeginEventArgs(bool cached, RegistrationType registrationType, int packageCount, bool cancelRecommendation)
            : base(cancelRecommendation)
        {
            this.Cached = cached;
-            this.Installed = installed;
+            this.RegistrationType = registrationType;
            this.PackageCount = packageCount;
        }
@@ -263,9 +263,9 @@ namespace WixToolset.Mba.Core
        public bool Cached { get; private set; }
        /// <summary>
-        /// Gets whether the bundle is installed.
+        /// Gets the bundle's registration state.
        /// </summary>
-        public bool Installed { get; private set; }
+        public RegistrationType RegistrationType { get; private set; }
        /// <summary>
        /// Gets the number of packages to detect.
diff --git a/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs b/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
index 4fbe5e18..489e3b6d 100644
--- a/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
+++ b/src/api/burn/WixToolset.Mba.Core/IBootstrapperApplication.cs
@@ -70,7 +70,7 @@ namespace WixToolset.Mba.Core
        [return: MarshalAs(UnmanagedType.I4)]
        int OnDetectBegin(
            [MarshalAs(UnmanagedType.Bool)] bool fCached,
-            [MarshalAs(UnmanagedType.Bool)] bool fInstalled,
+            [MarshalAs(UnmanagedType.U4)] RegistrationType registrationType,
            [MarshalAs(UnmanagedType.U4)] int cPackages,
            [MarshalAs(UnmanagedType.Bool)] ref bool fCancel
            );
diff --git a/src/api/burn/balutil/inc/BalBaseBAFunctions.h b/src/api/burn/balutil/inc/BalBaseBAFunctions.h
index e98ebc9f..60a70e3e 100644
--- a/src/api/burn/balutil/inc/BalBaseBAFunctions.h
+++ b/src/api/burn/balutil/inc/BalBaseBAFunctions.h
@@ -108,7 +108,7 @@ public: // IBootstrapperApplication
    virtual STDMETHODIMP OnDetectBegin(
        __in BOOL /*fCached*/,
-        __in BOOL /*fInstalled*/,
+        __in BOOTSTRAPPER_REGISTRATION_TYPE /*registrationType*/,
        __in DWORD /*cPackages*/,
        __inout BOOL* /*pfCancel*/
        )
diff --git a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
index 6a24f24b..7b3cf827 100644
--- a/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
+++ b/src/api/burn/balutil/inc/BalBaseBootstrapperApplication.h
@@ -109,7 +109,7 @@ public: // IBootstrapperApplication
    virtual STDMETHODIMP OnDetectBegin(
        __in BOOL /*fCached*/,
-        __in BOOL /*fInstalled*/,
+        __in BOOTSTRAPPER_REGISTRATION_TYPE /*registrationType*/,
        __in DWORD /*cPackages*/,
        __inout BOOL* pfCancel
        )
diff --git a/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h b/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
index d40390e5..8c3b8b72 100644
--- a/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
+++ b/src/api/burn/balutil/inc/BalBaseBootstrapperApplicationProc.h
@@ -15,7 +15,7 @@ static HRESULT BalBaseBAProcOnDetectBegin(
    __inout BA_ONDETECTBEGIN_RESULTS* pResults
    )
 {
-    return pBA->OnDetectBegin(pArgs->fCached, pArgs->fInstalled, pArgs->cPackages, &pResults->fCancel);
+    return pBA->OnDetectBegin(pArgs->fCached, pArgs->registrationType, pArgs->cPackages, &pResults->fCancel);
 }
 static HRESULT BalBaseBAProcOnDetectComplete(
diff --git a/src/api/burn/balutil/inc/IBootstrapperApplication.h b/src/api/burn/balutil/inc/IBootstrapperApplication.h
index 5932c06e..e916d41e 100644
--- a/src/api/burn/balutil/inc/IBootstrapperApplication.h
+++ b/src/api/burn/balutil/inc/IBootstrapperApplication.h
@@ -42,7 +42,7 @@ DECLARE_INTERFACE_IID_(IBootstrapperApplication, IUnknown, "53C31D56-49C0-426B-A
    // OnDetectBegin - called when the engine begins detection.
    STDMETHOD(OnDetectBegin)(
        __in BOOL fCached,
-        __in BOOL fInstalled,
+        __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
        __in DWORD cPackages,
        __inout BOOL* pfCancel
        ) = 0;
diff --git a/src/burn/engine/core.cpp b/src/burn/engine/core.cpp
index 9d5364a4..ca4d607b 100644
--- a/src/burn/engine/core.cpp
+++ b/src/burn/engine/core.cpp
@@ -315,26 +315,19 @@ extern "C" HRESULT CoreDetect(
    DetectReset(&pEngineState->registration, &pEngineState->packages);
    PlanReset(&pEngineState->plan, &pEngineState->containers, &pEngineState->packages, &pEngineState->layoutPayloads);
-    // Detect if bundle installed state has changed since start up. This
+    // Detect if bundle installed state has changed since start up.
-    // only happens if Apply() changed the state of bundle (installed or
+    // This only happens if Apply() changed the state of bundle (installed, in progress, or uninstalled).
-    // uninstalled). In that case, Detect() can be used here to reset
+    // In that case, Detect() can be used here to reset the installed state.
-    // the installed state.
+    // Of course, there's also cases outside of this bundle's control,
+    // like other processes messing with its registration.
    hr = RegistrationDetectInstalled(&pEngineState->registration);
    ExitOnFailure(hr, "Failed to detect bundle install state.");
-    if (pEngineState->registration.fInstalled)
+    hr = RegistrationSetDynamicVariables(&pEngineState->registration, &pEngineState->variables);
-    {
+    ExitOnFailure(hr, "Failed to reset the dynamic registration variables during detect.");
-        hr = VariableSetNumeric(&pEngineState->variables, BURN_BUNDLE_INSTALLED, 1, TRUE);
-        ExitOnFailure(hr, "Failed to set the bundle installed built-in variable.");
-    }
-    else
-    {
-        hr = VariableSetString(&pEngineState->variables, BURN_BUNDLE_INSTALLED, NULL, TRUE, FALSE);
-        ExitOnFailure(hr, "Failed to unset the bundle installed built-in variable.");
-    }
    fDetectBegan = TRUE;
-    hr = UserExperienceOnDetectBegin(&pEngineState->userExperience, pEngineState->registration.fCached, pEngineState->registration.fInstalled, pEngineState->packages.cPackages);
+    hr = UserExperienceOnDetectBegin(&pEngineState->userExperience, pEngineState->registration.fCached, pEngineState->registration.detectedRegistrationType, pEngineState->packages.cPackages);
    ExitOnRootFailure(hr, "UX aborted detect begin.");
    pEngineState->userExperience.hwndDetect = hwndParent;
@@ -444,7 +437,7 @@ LExit:
    pEngineState->userExperience.hwndDetect = NULL;
-    LogId(REPORT_STANDARD, MSG_DETECT_COMPLETE, hr, !fDetectBegan ? "(failed)" : LoggingBoolToString(pEngineState->registration.fInstalled), !fDetectBegan ? "(failed)" : LoggingBoolToString(pEngineState->registration.fCached), FAILED(hr) ? "(failed)" : LoggingBoolToString(pEngineState->registration.fEligibleForCleanup));
+    LogId(REPORT_STANDARD, MSG_DETECT_COMPLETE, hr, !fDetectBegan ? "(failed)" : LoggingRegistrationTypeToString(pEngineState->registration.detectedRegistrationType), !fDetectBegan ? "(failed)" : LoggingBoolToString(pEngineState->registration.fCached), FAILED(hr) ? "(failed)" : LoggingBoolToString(pEngineState->registration.fEligibleForCleanup));
    return hr;
 }
@@ -489,7 +482,7 @@ extern "C" HRESULT CorePlan(
    pEngineState->plan.wzBundleId = pEngineState->registration.sczId;
    pEngineState->plan.wzBundleProviderKey = pEngineState->registration.sczId;
    pEngineState->plan.fDisableRollback = pEngineState->fDisableRollback || BOOTSTRAPPER_ACTION_UNSAFE_UNINSTALL == pEngineState->plan.action;
-    pEngineState->plan.fBundleAlreadyRegistered = pEngineState->registration.fInstalled;
+    pEngineState->plan.fPlanPackageCacheRollback = BOOTSTRAPPER_REGISTRATION_TYPE_NONE == pEngineState->registration.detectedRegistrationType;
    hr = PlanSetVariables(action, &pEngineState->variables);
    ExitOnFailure(hr, "Failed to update action.");
diff --git a/src/burn/engine/detect.cpp b/src/burn/engine/detect.cpp
index 3bd39784..f7a030ff 100644
--- a/src/burn/engine/detect.cpp
+++ b/src/burn/engine/detect.cpp
@@ -165,7 +165,7 @@ extern "C" HRESULT DetectReportRelatedBundles(
 {
    HRESULT hr = S_OK;
    BOOTSTRAPPER_REQUEST_STATE uninstallRequestState = BOOTSTRAPPER_REQUEST_STATE_NONE;
-    *pfEligibleForCleanup = pRegistration->fInstalled || pRegistration->fCached;
+    *pfEligibleForCleanup = BOOTSTRAPPER_REGISTRATION_TYPE_NONE != pRegistration->detectedRegistrationType || pRegistration->fCached;
    for (DWORD iRelatedBundle = 0; iRelatedBundle < pRegistration->relatedBundles.cRelatedBundles; ++iRelatedBundle)
    {
diff --git a/src/burn/engine/engine.mc b/src/burn/engine/engine.mc
index 4425af12..6a826365 100644
--- a/src/burn/engine/engine.mc
+++ b/src/burn/engine/engine.mc
@@ -335,7 +335,7 @@ MessageId=199
 Severity=Success
 SymbolicName=MSG_DETECT_COMPLETE
 Language=English
-Detect complete, result: 0x%1!x!, installed: %2!hs!, cached: %3!hs!, eligible for cleanup: %4!hs!
+Detect complete, result: 0x%1!x!, registration state: %2!hs!, cached: %3!hs!, eligible for cleanup: %4!hs!
 .
 MessageId=200
diff --git a/src/burn/engine/plan.cpp b/src/burn/engine/plan.cpp
index 49dd83f4..c9337df5 100644
--- a/src/burn/engine/plan.cpp
+++ b/src/burn/engine/plan.cpp
@@ -1692,7 +1692,7 @@ extern "C" HRESULT PlanExecuteCacheSyncAndRollback(
    HRESULT hr = S_OK;
    BURN_EXECUTE_ACTION* pAction = NULL;
-    if (!pPlan->fBundleAlreadyRegistered)
+    if (pPlan->fPlanPackageCacheRollback)
    {
        hr = PlanAppendRollbackAction(pPlan, &pAction);
        ExitOnFailure(hr, "Failed to append rollback action.");
@@ -2241,7 +2241,7 @@ static HRESULT AddCachePackageHelper(
    pCacheAction->type = BURN_CACHE_ACTION_TYPE_CHECKPOINT;
    pCacheAction->checkpoint.dwId = dwCheckpoint;
-    if (!pPlan->fBundleAlreadyRegistered)
+    if (pPlan->fPlanPackageCacheRollback)
    {
        // Create a package cache rollback action *before* the checkpoint.
        hr = AppendRollbackCacheAction(pPlan, &pCacheAction);
diff --git a/src/burn/engine/plan.h b/src/burn/engine/plan.h
index c0936970..63bcd3ce 100644
--- a/src/burn/engine/plan.h
+++ b/src/burn/engine/plan.h
@@ -249,7 +249,7 @@ typedef struct _BURN_PLAN
    BOOL fDisableRollback;
    BOOL fAffectedMachineState;
    LPWSTR sczLayoutDirectory;
-    BOOL fBundleAlreadyRegistered;
+    BOOL fPlanPackageCacheRollback;
    DWORD64 qwCacheSizeTotal;
diff --git a/src/burn/engine/registration.cpp b/src/burn/engine/registration.cpp
index a1b1b607..fcefe5e0 100644
--- a/src/burn/engine/registration.cpp
+++ b/src/burn/engine/registration.cpp
@@ -69,6 +69,7 @@ static HRESULT UpdateResumeMode(
    __in BURN_REGISTRATION* pRegistration,
    __in HKEY hkRegistration,
    __in BURN_RESUME_MODE resumeMode,
+    __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
    __in BOOL fRestartInitiated
    );
 static HRESULT ParseRelatedCodes(
@@ -444,11 +445,8 @@ extern "C" HRESULT RegistrationSetVariables(
    HRESULT hr = S_OK;
    LPWSTR scz = NULL;
-    if (pRegistration->fInstalled)
+    hr = RegistrationSetDynamicVariables(pRegistration, pVariables);
-    {
+    ExitOnFailure(hr, "Failed to set the dynamic registration variables.");
-        hr = VariableSetNumeric(pVariables, BURN_BUNDLE_INSTALLED, 1, TRUE);
-        ExitOnFailure(hr, "Failed to set the bundle installed built-in variable.");
-    }
    // Ensure the registration bundle name is updated.
    hr = GetBundleInProgressName(pRegistration, pVariables, &scz);
@@ -469,12 +467,32 @@ extern "C" HRESULT RegistrationSetVariables(
    hr = VariableSetVersion(pVariables, BURN_BUNDLE_VERSION, pRegistration->pVersion, TRUE);
    ExitOnFailure(hr, "Failed to overwrite the bundle version built-in variable.");
+LExit:
+    ReleaseStr(scz);
+    return hr;
+}
+/*******************************************************************
+ RegistrationSetDynamicVariables - Initializes bundle variables that
+     map to registration entities that can change during execution.
+*******************************************************************/
+extern "C" HRESULT RegistrationSetDynamicVariables(
+    __in BURN_REGISTRATION* pRegistration,
+    __in BURN_VARIABLES* pVariables
+    )
+{
+    HRESULT hr = S_OK;
+    LONGLONG llInstalled = BOOTSTRAPPER_REGISTRATION_TYPE_FULL == pRegistration->detectedRegistrationType ? 1 : 0;
+    hr = VariableSetNumeric(pVariables, BURN_BUNDLE_INSTALLED, llInstalled, TRUE);
+    ExitOnFailure(hr, "Failed to set the bundle installed built-in variable.");
    hr = VariableSetNumeric(pVariables, BURN_REBOOT_PENDING, IsWuRebootPending() || IsRegistryRebootPending(), TRUE);
    ExitOnFailure(hr, "Failed to overwrite the bundle reboot-pending built-in variable.");
 LExit:
-    ReleaseStr(scz);
    return hr;
 }
@@ -487,12 +505,15 @@ extern "C" HRESULT RegistrationDetectInstalled(
    DWORD dwInstalled = 0;
    pRegistration->fCached = FileExistsEx(pRegistration->sczCacheExecutablePath, NULL);
+    pRegistration->detectedRegistrationType = BOOTSTRAPPER_REGISTRATION_TYPE_NONE;
    // open registration key
    hr = RegOpen(pRegistration->hkRoot, pRegistration->sczRegistrationKey, KEY_QUERY_VALUE, &hkRegistration);
    if (SUCCEEDED(hr))
    {
        hr = RegReadNumber(hkRegistration, REGISTRY_BUNDLE_INSTALLED, &dwInstalled);
+        pRegistration->detectedRegistrationType = (1 == dwInstalled) ? BOOTSTRAPPER_REGISTRATION_TYPE_FULL : BOOTSTRAPPER_REGISTRATION_TYPE_INPROGRESS;
    }
    // Not finding the key or value is okay.
@@ -501,8 +522,6 @@ extern "C" HRESULT RegistrationDetectInstalled(
        hr = S_OK;
    }
-    pRegistration->fInstalled = (1 == dwInstalled);
    ReleaseRegKey(hkRegistration);
    return hr;
 }
@@ -833,7 +852,7 @@ extern "C" HRESULT RegistrationSessionBegin(
    }
    // update resume mode
-    hr = UpdateResumeMode(pRegistration, hkRegistration, BURN_RESUME_MODE_ACTIVE, FALSE);
+    hr = UpdateResumeMode(pRegistration, hkRegistration, BURN_RESUME_MODE_ACTIVE, registrationType, FALSE);
    ExitOnFailure(hr, "Failed to update resume mode.");
 LExit:
@@ -864,7 +883,7 @@ extern "C" HRESULT RegistrationSessionResume(
    ExitOnFailure(hr, "Failed to open registration key.");
    // update resume mode
-    hr = UpdateResumeMode(pRegistration, hkRegistration, BURN_RESUME_MODE_ACTIVE, FALSE);
+    hr = UpdateResumeMode(pRegistration, hkRegistration, BURN_RESUME_MODE_ACTIVE, registrationType, FALSE);
    ExitOnFailure(hr, "Failed to update resume mode.");
    // update display name
@@ -934,7 +953,7 @@ extern "C" HRESULT RegistrationSessionEnd(
    }
    // Update resume mode.
-    hr = UpdateResumeMode(pRegistration, hkRegistration, resumeMode, BOOTSTRAPPER_APPLY_RESTART_INITIATED == restart);
+    hr = UpdateResumeMode(pRegistration, hkRegistration, resumeMode, registrationType, BOOTSTRAPPER_APPLY_RESTART_INITIATED == restart);
    ExitOnFailure(hr, "Failed to update resume mode.");
 LExit:
@@ -1271,6 +1290,7 @@ static HRESULT UpdateResumeMode(
    __in BURN_REGISTRATION* pRegistration,
    __in HKEY hkRegistration,
    __in BURN_RESUME_MODE resumeMode,
+    __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
    __in BOOL fRestartInitiated
    )
 {
@@ -1289,16 +1309,9 @@ static HRESULT UpdateResumeMode(
        hr = RegWriteNumber(hkRegistration, L"Resume", (DWORD)resumeMode);
        ExitOnFailure(hr, "Failed to write Resume value.");
-        // Write the Installed value *only* when the mode is ARP. This will tell us
+        // Write Installed value.
-        // that the bundle considers itself "installed" on the machine. Note that we
+        hr = RegWriteNumber(hkRegistration, REGISTRY_BUNDLE_INSTALLED, BOOTSTRAPPER_REGISTRATION_TYPE_FULL == registrationType ? 1 : 0);
-        // never change the value to "0" after that. The bundle will be considered
+        ExitOnFailure(hr, "Failed to write Installed value.");
-        // "uninstalled" when all of the registration is removed.
-        if (BURN_RESUME_MODE_ARP == resumeMode)
-        {
-            // Write Installed value.
-            hr = RegWriteNumber(hkRegistration, REGISTRY_BUNDLE_INSTALLED, 1);
-            ExitOnFailure(hr, "Failed to write Installed value.");
-        }
    }
    // If the engine is active write the run key so we resume if there is an unexpected
diff --git a/src/burn/engine/registration.h b/src/burn/engine/registration.h
index 64191828..bfaab1f1 100644
--- a/src/burn/engine/registration.h
+++ b/src/burn/engine/registration.h
@@ -93,7 +93,7 @@ typedef struct _BURN_REGISTRATION
    BOOL fRegisterArp;
    BOOL fDisableResume;
    BOOL fCached;
-    BOOL fInstalled;
+    BOOTSTRAPPER_REGISTRATION_TYPE detectedRegistrationType;
    LPWSTR sczId;
    LPWSTR sczTag;
@@ -171,6 +171,10 @@ HRESULT RegistrationSetVariables(
    __in BURN_REGISTRATION* pRegistration,
    __in BURN_VARIABLES* pVariables
    );
+HRESULT RegistrationSetDynamicVariables(
+    __in BURN_REGISTRATION* pRegistration,
+    __in BURN_VARIABLES* pVariables
+    );
 HRESULT RegistrationDetectInstalled(
    __in BURN_REGISTRATION* pRegistration
    );
diff --git a/src/burn/engine/userexperience.cpp b/src/burn/engine/userexperience.cpp
index a2f33f80..f299772b 100644
--- a/src/burn/engine/userexperience.cpp
+++ b/src/burn/engine/userexperience.cpp
@@ -104,7 +104,7 @@ extern "C" HRESULT UserExperienceLoad(
    args.pCommand = pCommand;
    args.pfnBootstrapperEngineProc = EngineForApplicationProc;
    args.pvBootstrapperEngineProcContext = pEngineContext;
-    args.qwEngineAPIVersion = MAKEQWORDVERSION(2022, 2, 22, 0);
+    args.qwEngineAPIVersion = MAKEQWORDVERSION(2022, 3, 4, 0);
    results.cbSize = sizeof(BOOTSTRAPPER_CREATE_RESULTS);
@@ -988,7 +988,7 @@ LExit:
 EXTERN_C BAAPI UserExperienceOnDetectBegin(
    __in BURN_USER_EXPERIENCE* pUserExperience,
    __in BOOL fCached,
-    __in BOOL fInstalled,
+    __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
    __in DWORD cPackages
    )
 {
@@ -998,7 +998,7 @@ EXTERN_C BAAPI UserExperienceOnDetectBegin(
    args.cbSize = sizeof(args);
    args.cPackages = cPackages;
-    args.fInstalled = fInstalled;
+    args.registrationType = registrationType;
    args.fCached = fCached;
    results.cbSize = sizeof(results);
diff --git a/src/burn/engine/userexperience.h b/src/burn/engine/userexperience.h
index 8106d7f7..37fa5174 100644
--- a/src/burn/engine/userexperience.h
+++ b/src/burn/engine/userexperience.h
@@ -245,7 +245,7 @@ BAAPI UserExperienceOnCommitMsiTransactionComplete(
 BAAPI UserExperienceOnDetectBegin(
    __in BURN_USER_EXPERIENCE* pUserExperience,
    __in BOOL fCached,
-    __in BOOL fInstalled,
+    __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
    __in DWORD cPackages
    );
 BAAPI UserExperienceOnDetectCompatibleMsiPackage(
diff --git a/src/burn/engine/variable.cpp b/src/burn/engine/variable.cpp
index b3dcdb7d..5d92590c 100644
--- a/src/burn/engine/variable.cpp
+++ b/src/burn/engine/variable.cpp
@@ -248,6 +248,7 @@ extern "C" HRESULT VariableInitialize(
 #endif
        {L"ProgramFiles6432Folder", InitializeVariable6432Folder, CSIDL_PROGRAM_FILES},
        {L"ProgramMenuFolder", InitializeVariableCsidlFolder, CSIDL_PROGRAMS},
+        {L"RebootPending", InitializeVariableNumeric, 0},
        {L"SendToFolder", InitializeVariableCsidlFolder, CSIDL_SENDTO},
        {L"ServicePackLevel", InitializeVariableVersionNT, OS_INFO_VARIABLE_ServicePackLevel},
        {L"StartMenuFolder", InitializeVariableCsidlFolder, CSIDL_STARTMENU},
@@ -1571,6 +1572,9 @@ static HRESULT SetVariableValue(
    // Insert element if not found.
    if (S_FALSE == hr)
    {
+        // Not possible from external callers so just assert.
+        AssertSz(SET_VARIABLE_OVERRIDE_BUILTIN != setBuiltin, "Intent to set missing built-in variable.");
        hr = InsertVariable(pVariables, wzVariable, iVariable);
        ExitOnFailure(hr, "Failed to insert variable '%ls'.", wzVariable);
    }
diff --git a/src/burn/test/BurnUnitTest/PlanTest.cpp b/src/burn/test/BurnUnitTest/PlanTest.cpp
index ba28713f..685d2ca9 100644
--- a/src/burn/test/BurnUnitTest/PlanTest.cpp
+++ b/src/burn/test/BurnUnitTest/PlanTest.cpp
@@ -792,7 +792,7 @@ namespace Bootstrapper
            InitializeEngineStateForCorePlan(wzSingleMsiManifestFileName, pEngineState);
            DetectPackagesAsAbsent(pEngineState);
-            pEngineState->registration.fInstalled = TRUE;
+            pEngineState->registration.detectedRegistrationType = BOOTSTRAPPER_REGISTRATION_TYPE_FULL;
            hr = CorePlan(pEngineState, BOOTSTRAPPER_ACTION_MODIFY);
            NativeAssert::Succeeded(hr, "CorePlan failed");
@@ -1457,7 +1457,7 @@ namespace Bootstrapper
        {
            PlanTestDetect(pEngineState);
-            pEngineState->registration.fInstalled = TRUE;
+            pEngineState->registration.detectedRegistrationType = BOOTSTRAPPER_REGISTRATION_TYPE_FULL;
            for (DWORD i = 0; i < pEngineState->packages.cPackages; ++i)
            {
@@ -1486,7 +1486,7 @@ namespace Bootstrapper
        {
            PlanTestDetect(pEngineState);
-            pEngineState->registration.fInstalled = TRUE;
+            pEngineState->registration.detectedRegistrationType = BOOTSTRAPPER_REGISTRATION_TYPE_FULL;
            for (DWORD i = 0; i < pEngineState->packages.cPackages; ++i)
            {
diff --git a/src/burn/test/BurnUnitTest/RegistrationTest.cpp b/src/burn/test/BurnUnitTest/RegistrationTest.cpp
index 6a10961d..86ea86b0 100644
--- a/src/burn/test/BurnUnitTest/RegistrationTest.cpp
+++ b/src/burn/test/BurnUnitTest/RegistrationTest.cpp
@@ -218,7 +218,7 @@ namespace Bootstrapper
                // verify that registration was updated
                this->ValidateUninstallKeyResume(Int32(BURN_RESUME_MODE_ARP));
-                this->ValidateUninstallKeyInstalled(1);
+                this->ValidateUninstallKeyInstalled(0);
                this->ValidateRunOnceKeyString(TEST_BUNDLE_ID, nullptr);
                //
@@ -231,7 +231,7 @@ namespace Bootstrapper
                // verify that registration was updated
                this->ValidateUninstallKeyResume(Int32(BURN_RESUME_MODE_ACTIVE));
-                this->ValidateUninstallKeyInstalled(1);
+                this->ValidateUninstallKeyInstalled(0);
                this->ValidateRunOnceKeyEntry(cacheExePath);
                // delete registration
@@ -337,7 +337,7 @@ namespace Bootstrapper
                // verify that registration variables were updated
                this->ValidateUninstallKeyDisplayName(L"Product1");
-                registration.fInstalled = TRUE;
+                registration.detectedRegistrationType = BOOTSTRAPPER_REGISTRATION_TYPE_FULL;
                hr = RegistrationSetVariables(&registration, &variables);
                TestThrowOnFailure(hr, L"Failed to set registration variables.");
diff --git a/src/ext/Bal/Samples/bafunctions/WixSampleBAFunctions.cpp b/src/ext/Bal/Samples/bafunctions/WixSampleBAFunctions.cpp
index 870b219b..5383efbf 100644
--- a/src/ext/Bal/Samples/bafunctions/WixSampleBAFunctions.cpp
+++ b/src/ext/Bal/Samples/bafunctions/WixSampleBAFunctions.cpp
@@ -9,14 +9,14 @@ class CWixSampleBAFunctions : public CBalBaseBAFunctions
 public: // IBootstrapperApplication
    virtual STDMETHODIMP OnDetectBegin(
        __in BOOL fCached,
-        __in BOOL fInstalled,
+        __in BOOTSTRAPPER_REGISTRATION_TYPE registrationType,
        __in DWORD cPackages,
        __inout BOOL* pfCancel
        )
    {
        HRESULT hr = S_OK;
-        BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Running detect begin BA function. fCached=%d, fInstalled=%d, cPackages=%u, fCancel=%d", fCached, fInstalled, cPackages, *pfCancel);
+        BalLog(BOOTSTRAPPER_LOG_LEVEL_STANDARD, "Running detect begin BA function. fCached=%d, registrationType=%d, cPackages=%u, fCancel=%d", fCached, registrationType, cPackages, *pfCancel);
        //-------------------------------------------------------------------------------------------------
        // YOUR CODE GOES HERE
diff --git a/src/test/burn/WixToolset.WixBA/InstallationViewModel.cs b/src/test/burn/WixToolset.WixBA/InstallationViewModel.cs
index e056b943..3a71779a 100644
--- a/src/test/burn/WixToolset.WixBA/InstallationViewModel.cs
+++ b/src/test/burn/WixToolset.WixBA/InstallationViewModel.cs
@@ -53,9 +53,9 @@ namespace WixToolset.WixBA
    /// </summary>
    public class InstallationViewModel : PropertyNotifyBase
    {
-        private RootViewModel root;
+        private readonly RootViewModel root;
-        private Dictionary<string, int> downloadRetries;
+        private readonly Dictionary<string, int> downloadRetries;
        private bool downgrade;
        private string downgradeMessage;
@@ -407,7 +407,7 @@ namespace WixToolset.WixBA
        private void DetectBegin(object sender, DetectBeginEventArgs e)
        {
-            this.root.DetectState = e.Installed ? DetectionState.Present : DetectionState.Absent;
+            this.root.DetectState = RegistrationType.Full == e.RegistrationType ? DetectionState.Present : DetectionState.Absent;
            WixBA.Model.PlannedAction = LaunchAction.Unknown;
        }