diff --git a/lib/main.dart b/lib/main.dart
index 2496bf5f..c4f72141 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -58,6 +58,7 @@ import 'package:clide/src/editor/registry.dart' show EditorRegistry;
 import 'package:clide/src/git/client.dart';
 import 'package:clide/src/cli/argv_dispatch.dart';
 import 'package:clide/src/env/shell_env.dart' show primeLoginShellPath;
+import 'package:clide/src/env/supporter_binaries.dart';
 import 'package:clide/src/ipc/envelope.dart';
 import 'package:clide/src/ipc/mcp_server.dart';
 import 'package:clide/src/ipc/paths.dart' show workspaceSocketPath, logDirectory;
@@ -114,6 +115,13 @@ Future<void> main() async {
     await primeLoginShellPath();
     final bootSettings = SettingsStore(appDir: appDir);
     await bootSettings.load();
+    // Resolve external supporter binaries (claude, d2, …) — explicit user-scope
+    // overrides first, else the primed PATH + the well-known dirs; auto-detect
+    // and pin them on first run (T-495, D-104).
+    activeSupporterBinaries = await loadSupporterBinaries(
+      readOverrides: () => bootSettings.get<Map>(supporterToolsKey),
+      writeOverrides: (m) => bootSettings.set(supporterToolsKey, m),
+    );
     startupWorkRoot = resolveStartupWorkspace(
       cwdRoot: startupWorkRoot,
       lastProject: bootSettings.get<String>('app.lastProject'),
diff --git a/lib/src/env/supporter_binaries.dart b/lib/src/env/supporter_binaries.dart
index cfd44cc1..a1755df9 100644
--- a/lib/src/env/supporter_binaries.dart
+++ b/lib/src/env/supporter_binaries.dart
@@ -92,6 +92,11 @@ class SupporterBinaries {
 
 bool _fileExists(String p) => File(p).existsSync();
 
+/// The process-wide resolver, wired at boot via [loadSupporterBinaries]. Tool
+/// consumers (e.g. the d2 template, T-494) read it to resolve a binary; null in
+/// headless contexts where boot wiring hasn't run.
+SupporterBinaries? activeSupporterBinaries;
+
 /// The user-scope SettingsStore key (app layer, `~/.clide`, per-machine) holding
 /// the tool→absolute-path override map.
 const supporterToolsKey = 'app.tools';