diff --git a/CHANGELOG.md b/CHANGELOG.md
index f531668d..480b2550 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Import All no longer deletes items that are mapped in from another database, which could delete Embedded Git itself where it is mapped instance-wide (#997)
+- A custom pull event handler stored in the repository is now loaded and compiled before it runs, so operations on a freshly built instance no longer fail with `<CLASS DOES NOT EXIST>` (#1000)
 
 ## [2.17.1] - 2026-08-18
 
diff --git a/cls/SourceControl/Git/PullEventHandler.cls b/cls/SourceControl/Git/PullEventHandler.cls
index 5efd2c0e..104db0ae 100644
--- a/cls/SourceControl/Git/PullEventHandler.cls
+++ b/cls/SourceControl/Git/PullEventHandler.cls
@@ -1,3 +1,5 @@
+Include (%occStatus, %occErrors)
+
 /// Base class for all event handlers for git pull commands.
 /// Subclasses may override to perform an incremental load/compile, take no action, do a zpm "load", etc.
 Class SourceControl.Git.PullEventHandler Extends %RegisteredObject
@@ -28,16 +30,17 @@ ClassMethod ForModifications(ByRef files, pullEventClass As %String) As %Status
     #Dim pullError As %Exception.AbstractException
     #Dim st As %Status = $$$OK
     try {
+        set handlerClass = $select(
+            $data(pullEventClass)#2: pullEventClass,
+            1: ##class(SourceControl.Git.Utils).PullEventClass())
+        set st = ..BootstrapPullEventHandler(handlerClass)
+        quit:$$$ISERR(st)
         set log = ##class(SourceControl.Git.DeploymentLog).%New()
         set log.HeadRevision = ##class(SourceControl.Git.Utils).GetCurrentRevision()
         set log.StartTimestamp = $zdatetime($ztimestamp,3)
         set st = log.%Save()
         quit:$$$ISERR(st)
-        set event = $classmethod(
-            $select(
-                $data(pullEventClass)#2: pullEventClass,
-                1: ##class(SourceControl.Git.Utils).PullEventClass())
-            ,"%New")
+        set event = $classmethod(handlerClass,"%New")
         set event.LocalRoot = ##class(SourceControl.Git.Utils).TempFolder()
         merge event.ModifiedFiles = files
         try {
@@ -56,6 +59,36 @@ ClassMethod ForModifications(ByRef files, pullEventClass As %String) As %Status
     quit st
 }
 
+/// Makes sure <var>class</var> is compiled and can be instantiated, loading it from the
+/// local repository if needed. 
+ClassMethod BootstrapPullEventHandler(class As %String) As %Status [ Private ]
+{
+    quit:$$$comClassDefined(class) $$$OK
+
+    set internalName = class_".cls"
+    if ##class(%Dictionary.ClassDefinition).%ExistsId(class) {
+        write !, "Compiling pull event handler ", class
+        set source = "compiled from the definition already in the database"
+        set sc = $system.OBJ.Compile(class, "ck")
+    } else {
+        // nothing has been imported yet, so the handler is compiled on its own here:
+        // a handler kept in the repository it loads must be able to compile by itself.
+        set filename = ##class(SourceControl.Git.Utils).FullExternalName(internalName)
+        if '##class(%File).Exists(filename) {
+            quit $$$ERROR($$$GeneralError, "Pull event class '"_class_"' is not compiled and no source file exists at "_filename)
+        }
+        write !, "Importing pull event handler ", class
+        set source = "imported from "_filename
+        set sc = ##class(SourceControl.Git.Utils).ImportItem(internalName, 1, 0, 1)
+    }
+    quit:$$$ISERR(sc) sc
+
+    if '$$$comClassDefined(class) {
+        quit $$$ERROR($$$GeneralError, "Pull event class '"_class_"' was "_source_" but is still not available")
+    }
+    quit $$$OK
+}
+
 /// <var>InternalName</var> may be a comma-delimited string or $ListBuild list
 ClassMethod ForInternalNames(InternalName As %String) As %Status
 {
diff --git a/test/UnitTest/SourceControl/Git/PullEventHandler/CustomHandler.cls b/test/UnitTest/SourceControl/Git/PullEventHandler/CustomHandler.cls
new file mode 100644
index 00000000..4b2517d4
--- /dev/null
+++ b/test/UnitTest/SourceControl/Git/PullEventHandler/CustomHandler.cls
@@ -0,0 +1,99 @@
+/// Tests that a pull event handler living in the repository itself can be used
+/// on an instance where it has not been loaded/compiled yet - see issue #1000.
+Class UnitTest.SourceControl.Git.PullEventHandler.CustomHandler Extends UnitTest.SourceControl.Git.AbstractTest
+{
+
+/// Pull event handler class defined only in the working tree at the start of each test
+Parameter FixtureClass As STRING = "TestGit.PullHandlerFixture";
+
+/// Global the fixture's OnPull() increments, to prove it actually ran
+Parameter MarkerGlobal As STRING = "UnitTestPullHandlerFixture";
+
+Method TestHandlerNotInDatabase()
+{
+    do ..UseFixtureHandler(1)
+    set sc = ##class(SourceControl.Git.Utils).ImportAll(1)
+    do $$$AssertStatusOK(sc, "ImportAll succeeds with a pull event handler that is only in the repository")
+    do $$$AssertTrue($$$comClassDefined(..#FixtureClass), "pull event handler was compiled")
+    do $$$AssertEquals($get(@..MarkerRef()), 1, "pull event handler's OnPull() ran once")
+}
+
+Method TestHandlerLoadedButNotCompiled()
+{
+    do ..UseFixtureHandler(0)
+    set sc = ##class(SourceControl.Git.Utils).ImportAll(1)
+    do $$$AssertStatusOK(sc, "ImportAll succeeds when items are loaded without being compiled")
+    do $$$AssertTrue($$$comClassDefined(..#FixtureClass), "pull event handler was compiled")
+    do $$$AssertEquals($get(@..MarkerRef()), 1, "pull event handler's OnPull() ran once")
+}
+
+Method TestUnavailableHandlerReportsError()
+{
+    do ..UseFixtureHandler(1)
+    set settings = ##class(SourceControl.Git.Settings).%New()
+    set settings.pullEventClass = "TestGit.NoSuchPullHandler"
+    $$$ThrowOnError(settings.%Save())
+
+    set sc = ##class(SourceControl.Git.Utils).ImportAll(1)
+    set errorText = $system.Status.GetErrorText(sc)
+    do $$$AssertNotTrue($$$ISOK(sc), "ImportAll reports an error when the pull event handler cannot be loaded")
+    do $$$AssertTrue($find(errorText, "TestGit.NoSuchPullHandler") > 0, "error names the unavailable pull event handler")
+    do $$$AssertTrue($find(errorText, ##class(SourceControl.Git.Utils).FullExternalName("TestGit.NoSuchPullHandler.cls")) > 0, "error names the file that was looked for")
+    do $$$AssertNotTrue($find(errorText, "<CLASS DOES NOT EXIST>") > 0, "error is not a raw ObjectScript error")
+}
+
+/// Writes the fixture handler to the working tree, configures it as the pull event
+/// handler, and removes it from the database so it must be bootstrapped on import.
+Method UseFixtureHandler(compileOnImport As %Boolean)
+{
+    set settings = ##class(SourceControl.Git.Settings).%New()
+    set settings.pullEventClass = ..#FixtureClass
+    set settings.compileOnImport = compileOnImport
+    $$$ThrowOnError(settings.%Save())
+
+    do ..WriteFile(##class(SourceControl.Git.Utils).FullExternalName(..#FixtureClass_".cls"), ..FixtureSource())
+    do ..RemoveFixtureClass()
+    kill @..MarkerRef()
+}
+
+ClassMethod MarkerRef() As %String [ CodeMode = expression ]
+{
+"^"_..#MarkerGlobal
+}
+
+ClassMethod RemoveFixtureClass()
+{
+    if ##class(%Dictionary.ClassDefinition).%ExistsId(..#FixtureClass) || $$$comClassDefined(..#FixtureClass) {
+        $$$ThrowOnError($system.OBJ.Delete(..#FixtureClass, "-d"))
+    }
+    do ##class(SourceControl.Git.Utils).RemoveRoutineTSH(..#FixtureClass_".cls")
+}
+
+ClassMethod FixtureSource() As %String
+{
+    set lf = $char(10)
+    quit "Class "_..#FixtureClass_" Extends SourceControl.Git.PullEventHandler.IncrementalLoad"_lf_
+        "{"_lf_
+        lf_
+        "Parameter NAME = ""Unit Test Fixture"";"_lf_
+        lf_
+        "Parameter DESCRIPTION = ""Pull event handler used by unit tests."";"_lf_
+        lf_
+        "Method OnPull() As %Status"_lf_
+        "{"_lf_
+        "    set sc = ##super()"_lf_
+        "    set ^"_..#MarkerGlobal_" = $get(^"_..#MarkerGlobal_") + 1"_lf_
+        "    quit sc"_lf_
+        "}"_lf_
+        lf_
+        "}"_lf
+}
+
+Method %OnClose() As %Status [ Private, ServerOnly = 1 ]
+{
+    do ..RemoveFixtureClass()
+    kill @..MarkerRef()
+    quit ##super()
+}
+
+}