9p: rename s/ → session/ in filesystem namespace

The top-level sessions directory is now /session/ instead of /s/.
Clearer, self-documenting namespace. The agent/{aid} sublevel
will be added in a future change.

fs/perm.go

@@ -17,11 +17,11 @@ import "os"
 //	{file} — file name within a session directory
 const (
 	PathRoot        = "/"
-	PathSessions    = "/s/"
+	PathSessions    = "/session/"
 	PathElevate     = "/elevate/"
-	PathSessionDir  = "s/{id}"
+	PathSessionDir  = "session/{id}"
 	PathTools       = "t/"
-	PathSessionFile = "s/{id}/{file}"
+	PathSessionFile = "session/{id}/{file}"
 )
 
 // Perm declares permissions for a filesystem node.

server/server.go

@@ -257,7 +257,7 @@ func (s *Server) InGroup(group, user string) bool {
 }
 
 // fileOwnerGroup returns the uid and gid for a given path.
-// Session namespace (/s/{sid}/**) is owned by the agent principal with group "agent".
+// Session namespace (/session/{sid}/**) is owned by the agent principal with group "agent".
 // Everything else is owned by the current system user and their primary group.
 func (s *Server) fileOwnerGroup(path string) (uid, gid string) {
 	if strings.HasPrefix(path, fs.PathSessions) {
@@ -484,8 +484,8 @@ func fcallTypeName(t uint8) string {
 	}
 }
 
-// isSessionFile reports whether path is a fixed file directly under /s/
+// isSessionFile reports whether path is a fixed file directly under /session/
-// (i.e. /s/<name> where name is in sessionStoreFiles).
+// (i.e. /session/<name> where name is in sessionStoreFiles).
 func isSessionFile(path string) bool {
 	name, ok := strings.CutPrefix(path, fs.PathSessions)
 	if !ok || strings.Contains(name, "/") {
@@ -525,18 +525,18 @@ func (s *Server) pathType(path string) string {
 	if strings.HasPrefix(path, fs.PathSessions) {
 		name := strings.TrimPrefix(path, fs.PathSessions)
 		if !strings.Contains(name, "/") {
-			// /s/{name} — could be a session dir or a fixed file (new, idx, ls, etc.)
+			// /session/{name} — could be a session dir or a fixed file (new, idx, ls, etc.)
 			if isSessionFile(path) {
 				return "file"
 			}
 			return "dir"
 		}
-		// /s/{id}/peer or /s/{id}/proc — directory
+		// /session/{id}/peer or /session/{id}/proc — directory
 		parts := strings.SplitN(name, "/", 3)
 		if len(parts) == 2 && (parts[1] == "peer" || parts[1] == "proc") {
 			return "dir"
 		}
-		// /s/{id}/peer/{peer-id} — verify peer exists
+		// /session/{id}/peer/{peer-id} — verify peer exists
 		if len(parts) == 3 && parts[1] == "peer" {
 			sess := s.sessionMgr.Session(parts[0])
 			if sess == nil {
@@ -547,7 +547,7 @@ func (s *Server) pathType(path string) string {
 			}
 			return ""
 		}
-		// /s/{id}/proc/{pid} — verify PID exists in detached list
+		// /session/{id}/proc/{pid} — verify PID exists in detached list
 		if len(parts) == 3 && parts[1] == "proc" {
 			sess := s.sessionMgr.Session(parts[0])
 			if sess == nil {
@@ -560,7 +560,7 @@ func (s *Server) pathType(path string) string {
 			}
 			return ""
 		}
-		// /s/{id}/{file} — file
+		// /session/{id}/{file} — file
 		return "file"
 	}
 
@@ -1126,7 +1126,7 @@ func (s *Server) buildDirData(path string) []byte {
 	var dirs []plan9.Dir
 
 	if path == "/" {
-		rootEntries := []string{"agents", "backends", "complete", "ctl", "generate", "help", "models", "route", "s"}
+		rootEntries := []string{"agents", "backends", "complete", "ctl", "generate", "help", "models", "route", "session"}
 		for _, name := range rootEntries {
 			fpath := "/" + name
 			st := s.makeStat(fpath)
@@ -1145,7 +1145,7 @@ func (s *Server) buildDirData(path string) []byte {
 			dirs = append(dirs, d)
 		}
 	} else if st, name := s.route(path); st != nil {
-		// Subdirectory within a tree (e.g. /s/mysession, /s/mysession/t).
+		// Subdirectory within a tree (e.g. /session/mysession, /session/mysession/t).
 		type dirLister interface {
 			Readdir(string) ([]os.DirEntry, error)
 		}
@@ -1227,10 +1227,10 @@ func (s *Server) makeStat(path string) plan9.Dir {
 
 	// For chat and tailable mutable files, report actual size and
 	// Qid version so polling tools (tail -f) can detect changes via stat.
-	// Path format: /s/{sessid}/{file}
+	// Path format: /session/{sessid}/{file}
 	if strings.HasPrefix(path, fs.PathSessions) {
 		parts := strings.SplitN(strings.TrimPrefix(path, "/"), "/", 3)
-		if len(parts) == 3 && parts[0] == "s" {
+		if len(parts) == 3 && parts[0] == "session" {
 			if sess := s.sessionMgr.Session(parts[1]); sess != nil {
 				if base == "chat" {
 					length, vers := sess.LogInfo()