feat: mail uses wisps for ephemeral orchestration messages (gt-lg66)

Add dual-inbox architecture where ephemeral messages go to
.beads-wisp/.beads/ instead of .beads/. Lifecycle messages
(POLECAT_STARTED, NUDGE, etc.) auto-detect as ephemeral.

Changes:
- Add Ephemeral and Source fields to mail.Message
- Add --ephemeral flag to gt mail send
- Router auto-detects lifecycle message patterns
- Mailbox merges messages from both persistent and wisp storage
- Inbox displays (ephemeral) indicator for wisp messages
- Delete/archive works for both message types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/mail.go

@@ -22,6 +22,7 @@ var (
 	mailPriority      int
 	mailUrgent        bool
 	mailPinned        bool
+	mailEphemeral     bool
 	mailType          string
 	mailReplyTo       string
 	mailNotify        bool
@@ -235,6 +236,7 @@ func init() {
 	mailSendCmd.Flags().StringVar(&mailReplyTo, "reply-to", "", "Message ID this is replying to")
 	mailSendCmd.Flags().BoolVarP(&mailNotify, "notify", "n", false, "Send tmux notification to recipient")
 	mailSendCmd.Flags().BoolVar(&mailPinned, "pinned", false, "Pin message (for handoff context that persists)")
+	mailSendCmd.Flags().BoolVar(&mailEphemeral, "ephemeral", false, "Send as ephemeral wisp (auto-cleanup on patrol squash)")
 	mailSendCmd.Flags().BoolVar(&mailSendSelf, "self", false, "Send to self (auto-detect from cwd)")
 	_ = mailSendCmd.MarkFlagRequired("subject")
 
@@ -332,6 +334,9 @@ func runMailSend(cmd *cobra.Command, args []string) error {
 	// Set pinned flag
 	msg.Pinned = mailPinned
 
+	// Set ephemeral flag
+	msg.Ephemeral = mailEphemeral
+
 	// Handle reply-to: auto-set type to reply and look up thread
 	if mailReplyTo != "" {
 		msg.ReplyTo = mailReplyTo
@@ -434,8 +439,12 @@ func runMailInbox(cmd *cobra.Command, args []string) error {
 		if msg.Priority == mail.PriorityHigh || msg.Priority == mail.PriorityUrgent {
 			priorityMarker = " " + style.Bold.Render("!")
 		}
+		ephemeralMarker := ""
+		if msg.Ephemeral || msg.Source == mail.SourceWisp {
+			ephemeralMarker = " " + style.Dim.Render("(ephemeral)")
+		}
 
-		fmt.Printf("  %s %s%s%s\n", readMarker, msg.Subject, typeMarker, priorityMarker)
+		fmt.Printf("  %s %s%s%s%s\n", readMarker, msg.Subject, typeMarker, priorityMarker, ephemeralMarker)
 		fmt.Printf("    %s from %s\n",
 			style.Dim.Render(msg.ID),
 			msg.From)

internal/cmd/spawn.go

@@ -395,13 +395,14 @@ func runSpawn(cmd *cobra.Command, args []string) error {
 	sender := detectSender()
 	sessionName := sessMgr.SessionName(polecatName)
 
-	// Notify Witness with POLECAT_STARTED message
+	// Notify Witness with POLECAT_STARTED message (ephemeral - lifecycle ping)
 	witnessAddr := fmt.Sprintf("%s/witness", rigName)
 	witnessNotification := &mail.Message{
-		To:      witnessAddr,
-		From:    sender,
-		Subject: fmt.Sprintf("POLECAT_STARTED %s", polecatName),
-		Body:    fmt.Sprintf("Issue: %s\nSession: %s", assignmentID, sessionName),
+		To:        witnessAddr,
+		From:      sender,
+		Subject:   fmt.Sprintf("POLECAT_STARTED %s", polecatName),
+		Body:      fmt.Sprintf("Issue: %s\nSession: %s", assignmentID, sessionName),
+		Ephemeral: true,
 	}
 
 	if err := townRouter.Send(witnessNotification); err != nil {
@@ -410,13 +411,14 @@ func runSpawn(cmd *cobra.Command, args []string) error {
 		fmt.Printf("  %s\n", style.Dim.Render("Witness notified of polecat start"))
 	}
 
-	// Notify Deacon with POLECAT_STARTED message (includes full rig/polecat address)
+	// Notify Deacon with POLECAT_STARTED message (ephemeral - lifecycle ping)
 	deaconAddr := "deacon/"
 	deaconNotification := &mail.Message{
-		To:      deaconAddr,
-		From:    sender,
-		Subject: fmt.Sprintf("POLECAT_STARTED %s/%s", rigName, polecatName),
-		Body:    fmt.Sprintf("Issue: %s\nSession: %s", assignmentID, sessionName),
+		To:        deaconAddr,
+		From:      sender,
+		Subject:   fmt.Sprintf("POLECAT_STARTED %s/%s", rigName, polecatName),
+		Body:      fmt.Sprintf("Issue: %s\nSession: %s", assignmentID, sessionName),
+		Ephemeral: true,
 	}
 
 	if err := townRouter.Send(deaconNotification); err != nil {