diff --git a/app/src/main/java/com/droiddeck/launcher/session/ProtonExtras.kt b/app/src/main/java/com/droiddeck/launcher/session/ProtonExtras.kt
index 962291d2c..d17d40df4 100644
--- a/app/src/main/java/com/droiddeck/launcher/session/ProtonExtras.kt
+++ b/app/src/main/java/com/droiddeck/launcher/session/ProtonExtras.kt
@@ -48,11 +48,19 @@ object ProtonExtras {
 
     internal fun installedIn(dir: File, tool: Tool): List<String> =
         dir.listFiles()
-            ?.filter { it.isDirectory && it.name.startsWith(tool.prefix) && File(it, "toolmanifest.vdf").isFile }
+            ?.filter { it.isDirectory && it.name.startsWith(tool.prefix) && usable(it) }
             ?.map { it.name }
             ?.sortedWith { a, b -> compareVersions(a, b) }
             ?: emptyList()
 
+    private fun usable(dir: File): Boolean {
+        val manifest = runCatching { File(dir, "toolmanifest.vdf").readText() }.getOrNull() ?: return false
+        val command = Regex("\\\"commandline\\\"\\s+\\\"/?([^\\\" ]+)").find(manifest)?.groupValues?.getOrNull(1) ?: return false
+        val compat = runCatching { File(dir, "compatibilitytool.vdf").readText() }.getOrNull() ?: return false
+        return Regex("\\\"from_oslist\\\"\\s+\\\"[^\\\"]*windows", RegexOption.IGNORE_CASE).containsMatchIn(compat) &&
+            File(dir, command).isFile && File(dir, command).canExecute()
+    }
+
     private val ARCH = Regex("(?i)aarch64|arm64|x86_64|x86-64|amd64")
     private val NUMBER = Regex("\\d+")
 
diff --git a/app/src/test/java/com/droiddeck/launcher/ProtonMenuAutoTest.kt b/app/src/test/java/com/droiddeck/launcher/ProtonMenuAutoTest.kt
index 7aff48691..14dbdb833 100644
--- a/app/src/test/java/com/droiddeck/launcher/ProtonMenuAutoTest.kt
+++ b/app/src/test/java/com/droiddeck/launcher/ProtonMenuAutoTest.kt
@@ -83,7 +83,9 @@ class ProtonMenuAutoTest {
 
     private fun install(name: String): File = File(root, "root/.local/share/Steam/compatibilitytools.d/$name").apply {
         mkdirs()
-        File(this, "toolmanifest.vdf").writeText("manifest")
+        File(this, "toolmanifest.vdf").writeText("\"manifest\" { \"commandline\" \"/proton %verb%\" }")
+        File(this, "compatibilitytool.vdf").writeText("\"from_oslist\" \"windows\"")
+        File(this, "proton").apply { writeText(""); setExecutable(true) }
     }
 
     private fun waitUntil(done: () -> Boolean) {
diff --git a/app/src/test/java/com/droiddeck/launcher/session/ProtonExtrasTest.kt b/app/src/test/java/com/droiddeck/launcher/session/ProtonExtrasTest.kt
index 411268ef6..43571a3ff 100644
--- a/app/src/test/java/com/droiddeck/launcher/session/ProtonExtrasTest.kt
+++ b/app/src/test/java/com/droiddeck/launcher/session/ProtonExtrasTest.kt
@@ -44,6 +44,8 @@ class ProtonExtrasTest {
     private fun installTool(parent: File, name: String) = File(parent, name).apply {
         mkdirs()
         File(this, "toolmanifest.vdf").writeText("\"manifest\" { \"commandline\" \"/proton %verb%\" }")
+        File(this, "compatibilitytool.vdf").writeText("\"from_oslist\" \"windows\"")
+        File(this, "proton").apply { writeText(""); setExecutable(true) }
     }
 
     @Test
@@ -120,6 +122,17 @@ class ProtonExtrasTest {
         assertEquals(emptyList<String>(), ProtonExtras.installedIn(File(tools, "missing"), tool("ge")))
     }
 
+    @Test
+    fun interruptedBuildsAreNotReportedAsInstalled() {
+        val tools = temp.newFolder("compatibilitytools.d")
+        installTool(tools, "GE-Proton11-10")
+        File(tools, "GE-Proton11-11").apply {
+            mkdirs()
+            File(this, "toolmanifest.vdf").writeText("\"manifest\" { \"commandline\" \"/proton %verb%\" }")
+        }
+        assertEquals(listOf("GE-Proton11-10"), ProtonExtras.installedIn(tools, tool("ge")))
+    }
+
     @Test
     fun anUpdateIsANewerReleaseThanTheNewestInstalledBuild() {
         assertEquals("DroidDeck-Proton-11-7.6", ProtonExtras.updateFor(listOf("DroidDeck-Proton 11-7.5"), "DroidDeck-Proton-11-7.6"))
diff --git a/tools/linuxfs/overlay/usr/local/bin/droiddeck-proton-run b/tools/linuxfs/overlay/usr/local/bin/droiddeck-proton-run
index 3d2b6ec6f..164dbd028 100644
--- a/tools/linuxfs/overlay/usr/local/bin/droiddeck-proton-run
+++ b/tools/linuxfs/overlay/usr/local/bin/droiddeck-proton-run
@@ -70,8 +70,19 @@ def mapping(root):
 
 
 def tools(root):
+    c = compat()
+    wrapper = os.path.join(root, "compatibilitytools.d", c["TOOL"])
+    complete = os.access(os.path.join(wrapper, c["LAUNCHER"]), os.X_OK) and os.path.isfile(os.path.join(wrapper, "toolmanifest.vdf"))
+    if c["TOOL"].lower() not in c["local_tools"](root) or not complete:
+        depot = c["find_source"](root, runnable=True)
+        if depot is not None:
+            try:
+                c["build_tool"](wrapper, depot)
+            except OSError:
+                pass
     found = {}
-    for base in [os.path.join(root, "compatibilitytools.d")] + list(SYSTEM_TOOLS):
+    bases = [os.path.join(root, "compatibilitytools.d")] + list(SYSTEM_TOOLS)
+    for base in bases:
         try:
             entries = sorted(os.listdir(base))
         except OSError:
diff --git a/tools/linuxfs/overlay/usr/local/bin/steam-compatibility b/tools/linuxfs/overlay/usr/local/bin/steam-compatibility
index 5695bd0b1..4a2cbcb15 100755
--- a/tools/linuxfs/overlay/usr/local/bin/steam-compatibility
+++ b/tools/linuxfs/overlay/usr/local/bin/steam-compatibility
@@ -1599,10 +1599,11 @@ def depot_build(depot):
     return int(first[0]) if first and first[0].isdigit() else 0
 
 
-def find_source(steam_root, sources=SOURCES):
+def find_source(steam_root, sources=SOURCES, runnable=False):
     for name in sources:
         found = [os.path.join(root, "steamapps", "common", name) for root in libraries(steam_root)
-                 if os.path.isdir(os.path.join(root, "steamapps", "common", name, "files", "bin-arm64"))]
+                 if os.path.isdir(os.path.join(root, "steamapps", "common", name, "files", "bin-arm64"))
+                 and (not runnable or os.access(os.path.join(root, "steamapps", "common", name, "proton"), os.X_OK))]
         if found:
             return max(found, key=depot_build)
     return None
diff --git a/tools/tests/test_desktop_open.py b/tools/tests/test_desktop_open.py
index a23d85544..c32baf71a 100644
--- a/tools/tests/test_desktop_open.py
+++ b/tools/tests/test_desktop_open.py
@@ -482,6 +482,83 @@ class ProtonRunTest(Temp):
         self.assertEqual(found["droiddeck-proton-arm64"],
                          (str(self.root / "compatibilitytools.d/droiddeck-proton-arm64"), "droiddeck-proton"))
 
+    def test_a_valve_depot_is_registered_through_the_droiddeck_wrapper(self):
+        name = "Proton Experimental (ARM64)"
+        folder = "steamapps/common/%s" % name
+        shutil.rmtree(self.root / "compatibilitytools.d/droiddeck-proton-arm64")
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        self.write("Steam/%s/toolmanifest.vdf" % folder, '"manifest"\n{\n  "commandline" "/proton %verb%"\n}\n')
+        self.write("Steam/%s/proton" % folder, b"#!/bin/sh\n", 0o755)
+        self.write("Steam/%s/files/bin-arm64/proton" % folder, b"#!/bin/sh\n", 0o755)
+        found = RUN["tools"](str(self.root))
+        wrapper = self.root / "compatibilitytools.d/droiddeck-proton-arm64"
+        self.assertEqual(found["droiddeck-proton-arm64"], (str(wrapper), "droiddeck-proton"))
+        self.assertNotIn(name, found)
+
+    def test_an_incomplete_valve_depot_is_not_registered(self):
+        name = "Proton Experimental (ARM64)"
+        folder = "steamapps/common/%s" % name
+        shutil.rmtree(self.root / "compatibilitytools.d/droiddeck-proton-arm64")
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        self.write("Steam/%s/toolmanifest.vdf" % folder, '"manifest"\n{\n  "commandline" "/proton %verb%"\n}\n')
+        self.write("Steam/%s/files/bin-arm64/proton" % folder, b"#!/bin/sh\n", 0o755)
+        found = RUN["tools"](str(self.root))
+        self.assertNotIn("droiddeck-proton-arm64", found)
+        self.assertFalse((self.root / "compatibilitytools.d/droiddeck-proton-arm64").exists())
+
+    def test_a_failed_wrapper_build_does_not_hide_existing_tools(self):
+        shutil.rmtree(self.root / "compatibilitytools.d/droiddeck-proton-arm64")
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        folder = "steamapps/common/Proton Experimental (ARM64)"
+        self.write("Steam/%s/proton" % folder, b"#!/bin/sh\n", 0o755)
+        self.write("Steam/%s/files/bin-arm64/proton" % folder, b"#!/bin/sh\n", 0o755)
+        build = mock.Mock(side_effect=OSError("read-only"))
+        with mock.patch.dict(RUN["compat"](), {"build_tool": build}):
+            found = RUN["tools"](str(self.root))
+        build.assert_called_once()
+        self.assertIn("droiddeck-proton-11-arm64", found)
+
+    def test_a_runnable_depot_is_chosen_over_a_newer_incomplete_one(self):
+        shutil.rmtree(self.root / "compatibilitytools.d/droiddeck-proton-arm64")
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        good = "Steam/steamapps/common/Proton Experimental (ARM64)"
+        self.write("%s/proton" % good, b"#!/bin/sh\n", 0o755)
+        self.write("%s/files/bin-arm64/proton" % good, b"#!/bin/sh\n", 0o755)
+        broken = "Library/steamapps/common/Proton Experimental (ARM64)"
+        self.write("Library/steamapps/libraryfolders.vdf", b"")
+        self.write("%s/version" % broken, b"2\n")
+        self.write("%s/files/bin-arm64/proton" % broken, b"#!/bin/sh\n", 0o755)
+        self.write("Steam/steamapps/libraryfolders.vdf", '"path" "%s"' % (self.tmp / "Library"))
+        compat = RUN["compat"]()
+        source = compat["find_source"]
+        self.assertEqual(source(str(self.root), runnable=True), str(self.tmp / good))
+
+    def test_a_registered_wrapper_without_its_launcher_is_rebuilt(self):
+        wrapper = self.root / "compatibilitytools.d/droiddeck-proton-arm64"
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        folder = "Steam/steamapps/common/Proton Experimental (ARM64)"
+        self.write("%s/proton" % folder, b"#!/bin/sh\n", 0o755)
+        self.write("%s/files/bin-arm64/proton" % folder, b"#!/bin/sh\n", 0o755)
+        launcher = wrapper / RUN["compat"]()["LAUNCHER"]
+        if launcher.exists():
+            launcher.unlink()
+        found = RUN["tools"](str(self.root))
+        self.assertTrue(os.access(launcher, os.X_OK))
+        self.assertIn("droiddeck-proton-arm64", found)
+
+    def test_a_registered_wrapper_without_its_manifest_is_rebuilt(self):
+        wrapper = self.root / "compatibilitytools.d/droiddeck-proton-arm64"
+        self.write("Steam/steamapps/appmanifest_4427310.acf", '"AppState" { "appid" "4427310" }')
+        folder = "Steam/steamapps/common/Proton Experimental (ARM64)"
+        self.write("%s/proton" % folder, b"#!/bin/sh\n", 0o755)
+        self.write("%s/files/bin-arm64/proton" % folder, b"#!/bin/sh\n", 0o755)
+        manifest = wrapper / "toolmanifest.vdf"
+        if manifest.exists():
+            manifest.unlink()
+        found = RUN["tools"](str(self.root))
+        self.assertTrue(manifest.is_file())
+        self.assertIn("droiddeck-proton-arm64", found)
+
     def test_steams_choice_for_the_title_then_its_default(self):
         available = RUN["tools"](str(self.root))
         current = RUN["mapping"](str(self.root))