1 files changed, 16 insertions, 12 deletions
diff --git a/src/main.zig b/src/main.zig
index b8cb6b2d..1104aeb8 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -304,19 +304,23 @@ fn nativeMain(init: std.process.Init) !void {
     // reading. Refused rather than resolved by declaration order, which would
     // silently drop whichever flag lost.
     if (detach != null and attach != null) return error.BadArgs;
-    // `--fs` mounts the acme control filesystem, and only a LOCAL session has
-    // one: `fs_service.start` is called inside tty.zig's `localSession` and
-    // gui.zig's equivalent, both of which an `--attach` skips entirely, and
-    // `detached/server.zig` never reads `opts.fs` at all. So `--fs` with either
-    // of these was parsed, stored, and then served by nobody.
+    // `--fs` mounts the acme control filesystem, and it needs a CORE to serve.
+    // `--attach` has none — it is a terminal whose state lives in another
+    // process — so the flag there would be parsed, stored, and served by
+    // nobody. Refused rather than dropped, and it is the stronger case of the
+    // line above: a contradiction is at least visible, whereas a silently
+    // dropped mount is invisible until someone waits for a directory that will
+    // never appear.
     //
-    // Refused for the same reason as the line above, and it is the stronger
-    // case: a contradiction is at least visible, whereas a silently dropped
-    // mount is invisible until someone waits for a directory that will never
-    // appear. Serving it instead would mean mounting FUSE in the detached core,
-    // which is a feature rather than a fix — `push_fs_reply` is one of the five
-    // host methods that core deliberately leaves null (docs/detached.md).
-    if (opts.fs != null and (detach != null or attach != null)) return error.BadArgs;
+    // `--detach` used to be refused here too, and is not any more. The reason
+    // given was that `push_fs_reply` was one of the host methods the detached
+    // core deliberately left null; it no longer is. A daemon mounts its own
+    // /dev/fuse and polls it in the same `poll(2)` as its frontends and its
+    // pane shells, which costs it one descriptor and no thread — strictly less
+    // than the desktop shells pay. `--detach --fs` is now the configuration
+    // that most wants a control filesystem, because it is the one whose panes
+    // outlive every terminal that could otherwise have scripted them.
+    if (opts.fs != null and attach != null) return error.BadArgs;
     // `--detach` replaces the frontend rather than choosing among them: the
     // core runs here, with no terminal, and the frontends are elsewhere on a
     // socket (src/detached/). It is checked before `platform` because it is not