diff --git a/src/sidebarProvider.ts b/src/sidebarProvider.ts
index 223d752..efa30fe 100644
--- a/src/sidebarProvider.ts
+++ b/src/sidebarProvider.ts
@@ -1082,7 +1082,12 @@ export class SidebarChatProvider implements vscode.WebviewViewProvider, BridgeIn
         const updated: ProjectProfile = {
             ...profile,
             architectureDocPath: result.docPath,
-            architectureAutoAttach: profile.architectureAutoAttach ?? true,
+            // [BUGFIX] Previously used `?? true`, but `??` only fallbacks on null/undefined.
+            // After a user Detach, `architectureAutoAttach === false`, so `false ?? true`
+            // stays `false` and the chip stays "detached — click Attach to re-enable"
+            // forever no matter how many times the user clicks Attach. The activation
+            // path is an explicit user intent to re-enable, so force `true` here.
+            architectureAutoAttach: true,
             architectureAutoUpdate: profile.architectureAutoUpdate ?? true,
             architectureLastUpdated: now,
             architectureLastScanSignature: result.scan.signature,