session: replace timestamp-prefix IDs with UUIDv4; show first segment in acme GUI

cmd/Ollie/main.go

@@ -153,15 +153,26 @@ func (sl *sessionList) refresh() {
 
 	sl.mu.Lock()
 	sl.allSIDs = nil
+	var display strings.Builder
 	for _, l := range lines {
 		if s := strings.TrimSpace(l); s != "" {
-			id, _, _ := strings.Cut(s, "\t")
+			id, rest, _ := strings.Cut(s, "\t")
 			sl.allSIDs = append(sl.allSIDs, id)
+			short := id
+			if idx := strings.IndexByte(id, '-'); idx > 0 {
+				short = id[:idx]
+			}
+			display.WriteString(short)
+			if rest != "" {
+				display.WriteByte('\t')
+				display.WriteString(rest)
+			}
+			display.WriteByte('\n')
 		}
 	}
 	sl.mu.Unlock()
 
-	sl.win.Write("body", []byte(raw+"\n"))
+	sl.win.Write("body", []byte(display.String()))
 	sl.win.Ctl("clean")
 }
 
@@ -173,8 +184,11 @@ func (sl *sessionList) resolveFullSID(text string) string {
 	sl.mu.Lock()
 	defer sl.mu.Unlock()
 	for _, sid := range sl.allSIDs {
-		parts := strings.Split(sid, "__")
-		if parts[len(parts)-1] == text {
+		short := sid
+		if idx := strings.IndexByte(sid, '-'); idx > 0 {
+			short = sid[:idx]
+		}
+		if short == text || sid == text {
 			return sid
 		}
 	}
@@ -238,7 +252,11 @@ func openChat(sid string) {
 		log.Printf("open chat %s: %v", sid, err)
 		return
 	}
-	winName := "ollie/sessions/" + sid
+	short := sid
+	if idx := strings.IndexByte(sid, '-'); idx > 0 {
+		short = sid[:idx]
+	}
+	winName := "ollie/sessions/" + short
 	if data, err := read9p("session/idx"); err == nil {
 		for _, line := range strings.Split(string(data), "\n") {
 			fields := strings.Split(line, "\t")

session/session.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -65,11 +64,14 @@ type Session struct {
 	saveTimer *time.Timer
 }
 
-// NewSessionID generates a unique, lexicographically sortable session identifier.
+// NewSessionID generates a UUIDv4 session identifier.
 func NewSessionID() string {
-	b := make([]byte, 3)
+	b := make([]byte, 16)
 	rand.Read(b) //nolint:errcheck
-	return strconv.FormatInt(time.Now().UnixNano(), 10) + "-" + fmt.Sprintf("%06x", b)
+	b[6] = (b[6] & 0x0f) | 0x40 // version 4
+	b[8] = (b[8] & 0x3f) | 0x80 // variant 10xx
+	return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
+		b[0:4], b[4:6], b[6:8], b[8:10], b[10:16])
 }
 
 // NextUncheckedStep returns the first unchecked step from plan bytes.