diff --git a/templates/nsis/include/extractAppPackage.nsh b/templates/nsis/include/extractAppPackage.nsh
index f5470bf52e923dc47266cea4684c76ef78ced451..6c4a4c193a2ca1dc2413482606b9be5c1c2aa1a9 100644
--- a/templates/nsis/include/extractAppPackage.nsh
+++ b/templates/nsis/include/extractAppPackage.nsh
@@ -1,4 +1,11 @@
 !macro extractEmbeddedAppPackage
+  # OpenCode: the custom include can install an update the running app already unpacked, and sets
+  # $R0 to "installed" when it did.
+  !ifmacrodef customInstallStagedApp
+    !insertmacro customInstallStagedApp
+    StrCmp $R0 "installed" extractEmbeddedAppPackageDone
+  !endif
+
   !ifdef COMPRESS
     SetCompress off
   !endif
@@ -13,6 +20,10 @@
   !endif
 
   !insertmacro decompress
+
+  !ifmacrodef customInstallStagedApp
+    extractEmbeddedAppPackageDone:
+  !endif
   !insertmacro custom_files_post_decompression
 !macroend
 
@@ -90,6 +101,15 @@
 !macroend
 
 !macro extractUsing7za FILE
+  # OpenCode: extract straight into an empty install directory. The copy through $PLUGINSDIR below
+  # only protects files that a running old version still holds, and an empty directory has none,
+  # so it would write the whole app a second time and delete it again on exit.
+  ${DirState} $OUTDIR $R0
+  ${if} $R0 != 1
+    Nsis7z::Extract "${FILE}"
+    Goto DoneExtract7za
+  ${endIf}
+
   Push $OUTDIR
   CreateDirectory "$PLUGINSDIR\7z-out"
   ClearErrors
diff --git a/templates/nsis/include/installer.nsh b/templates/nsis/include/installer.nsh
index 300ef3dd699d0f5a081b1934fcc22dbe12025bdb..6bc1c7f368208024c52aff9ae53f299ce4b632f3 100644
--- a/templates/nsis/include/installer.nsh
+++ b/templates/nsis/include/installer.nsh
@@ -90,7 +90,21 @@
       ${if} $installMode == "all"
         SetShellVarContext current
       ${endif}
-      !insertmacro copyFile "$EXEPATH" "$LOCALAPPDATA\${APP_INSTALLER_STORE_FILE}"
+      # OpenCode: an update runs from the updater's pending download next to this cache file, so hard
+      # link it instead of copying a few hundred MB. The updater replaces that download rather than
+      # rewriting it, so the link never changes under the cache.
+      ${StdUtils.GetParentPath} $R5 "$LOCALAPPDATA\${APP_INSTALLER_STORE_FILE}"
+      StrLen $R6 "$R5\"
+      StrCpy $R6 $EXEPATH $R6
+      ${if} $R6 == "$R5\"
+        Delete "$LOCALAPPDATA\${APP_INSTALLER_STORE_FILE}"
+        System::Call 'kernel32::CreateHardLinkW(w "$LOCALAPPDATA\${APP_INSTALLER_STORE_FILE}", w "$EXEPATH", p 0) i .R6'
+      ${else}
+        StrCpy $R6 0
+      ${endIf}
+      ${if} $R6 == 0
+        !insertmacro copyFile "$EXEPATH" "$LOCALAPPDATA\${APP_INSTALLER_STORE_FILE}"
+      ${endIf}
       ${if} $installMode == "all"
         SetShellVarContext all
       ${endif}