diff --git a/server/server.go b/server/server.go
index 537f19b..7f124c5 100644
--- a/server/server.go
+++ b/server/server.go
@@ -1018,49 +1018,15 @@ func (s *Server) makeStat(path string) plan9.Dir {
 			mode = plan9.DMDIR | 0755
 		}
 	} else {
-		switch base {
-		case "ctl":
-			mode = 0222 // owner+group+other write
-		case "prompt", "fifo.in":
-			mode = 0022 // group+other write; owner cannot write (no self-prompt)
-		case "chat", "usage", "cost", "ctxsz", "models", "fifo.out", "offset", "statewait", "systemprompt":
-			mode = 0444
-		case "cfg":
-			mode = 0666
-		case "tail":
-			mode = 0555
-		default:
-			if path == "/backends" || path == "/help" {
-				mode = 0444
-			} else if isSessionFile(path) {
-				mode_, _ := session.FileMode(base)
-				mode = plan9.Perm(mode_)
-			} else if strings.HasPrefix(path, "/a/") {
-				mode = 0666
-			} else if strings.HasPrefix(path, "/p/") {
-				mode = 0664
-			} else if strings.HasPrefix(path, "/m/") {
-				mode = 0666
-			} else if path == "/sk/idx" {
-				mode = 0444
-			} else if strings.HasPrefix(path, "/sk/") {
-				mode = 0664
-			} else if strings.HasPrefix(path, "/s/") {
-				parts := strings.SplitN(strings.TrimPrefix(path, "/s/"), "/", 3)
-				if len(parts) == 3 && parts[1] == "t" && parts[2] == "idx" {
-					mode = 0400
-				} else if len(parts) == 3 && parts[1] == "t" {
-					mode = 0500
-				} else {
-					mode = 0444
-				}
-			} else if strings.HasPrefix(path, "/u/") {
-				mode = 0555
-			} else if strings.HasPrefix(path, "/x/") {
-				mode = 0555
+		// Delegate to the backing tree for file mode.
+		if tree, name := s.route(path); tree != nil {
+			if info, err := tree.Stat(name); err == nil {
+				mode = plan9.Perm(info.Mode())
 			} else {
 				mode = 0444
 			}
+		} else {
+			mode = 0444
 		}
 	}
 
diff --git a/session/sessionfile.go b/session/sessionfile.go
index dc74225..016af1a 100644
--- a/session/sessionfile.go
+++ b/session/sessionfile.go
@@ -23,10 +23,10 @@ var FileList = []struct {
 }{
 	{"plan", 0666, false, false},
 	{"ctl", 0200, false, true},
-	{"prompt", 0200, false, true},
-	{"fifo.in", 0200, false, true},
+	{"prompt", 0466, false, true},
+	{"fifo.in", 0222, false, true},
 	{"fifo.out", 0444, true, false},
-	{"chat", 0666, false, false},
+	{"chat", 0444, false, false},
 	{"offset", 0444, false, false},
 	{"cfg", 0666, false, false},
 	{"state", 0444, false, false},