diff --git a/internal/cmd/crew_at.go b/internal/cmd/crew_at.go
index a19c4346..04d30773 100644
--- a/internal/cmd/crew_at.go
+++ b/internal/cmd/crew_at.go
@@ -8,6 +8,7 @@ import (
 	"github.com/steveyegge/gastown/internal/constants"
 	"github.com/steveyegge/gastown/internal/crew"
 	"github.com/steveyegge/gastown/internal/runtime"
+	"github.com/steveyegge/gastown/internal/session"
 	"github.com/steveyegge/gastown/internal/style"
 	"github.com/steveyegge/gastown/internal/tmux"
 	"github.com/steveyegge/gastown/internal/workspace"
@@ -162,11 +163,20 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 			return fmt.Errorf("getting pane ID: %w", err)
 		}
 
+		// Build startup beacon for predecessor discovery via /resume
+		// Use FormatStartupNudge instead of bare "gt prime" which confuses agents
+		// The SessionStart hook handles context injection (gt prime --hook)
+		address := fmt.Sprintf("%s/crew/%s", r.Name, name)
+		beacon := session.FormatStartupNudge(session.StartupNudgeConfig{
+			Recipient: address,
+			Sender:    "human",
+			Topic:     "start",
+		})
+
 		// Use respawn-pane to replace shell with runtime directly
 		// This gives cleaner lifecycle: runtime exits → session ends (no intermediate shell)
-		// Pass "gt prime" as initial prompt if supported
 		// Export GT_ROLE and BD_ACTOR since tmux SetEnvironment only affects new panes
-		startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, "gt prime", crewAgentOverride)
+		startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, beacon, crewAgentOverride)
 		if err != nil {
 			return fmt.Errorf("building startup command: %w", err)
 		}
@@ -198,10 +208,18 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 				return fmt.Errorf("getting pane ID: %w", err)
 			}
 
+			// Build startup beacon for predecessor discovery via /resume
+			// Use FormatStartupNudge instead of bare "gt prime" which confuses agents
+			address := fmt.Sprintf("%s/crew/%s", r.Name, name)
+			beacon := session.FormatStartupNudge(session.StartupNudgeConfig{
+				Recipient: address,
+				Sender:    "human",
+				Topic:     "restart",
+			})
+
 			// Use respawn-pane to replace shell with runtime directly
-			// Pass "gt prime" as initial prompt if supported
 			// Export GT_ROLE and BD_ACTOR since tmux SetEnvironment only affects new panes
-			startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, "gt prime", crewAgentOverride)
+			startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, beacon, crewAgentOverride)
 			if err != nil {
 				return fmt.Errorf("building startup command: %w", err)
 			}
@@ -218,13 +236,19 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 	// Check if we're already in the target session
 	if isInTmuxSession(sessionID) {
 		// We're in the session at a shell prompt - just start the agent directly
-		// Pass "gt prime" as initial prompt so it loads context immediately
+		// Build startup beacon for predecessor discovery via /resume
+		address := fmt.Sprintf("%s/crew/%s", r.Name, name)
+		beacon := session.FormatStartupNudge(session.StartupNudgeConfig{
+			Recipient: address,
+			Sender:    "human",
+			Topic:     "start",
+		})
 		agentCfg, _, err := config.ResolveAgentConfigWithOverride(townRoot, r.Path, crewAgentOverride)
 		if err != nil {
 			return fmt.Errorf("resolving agent: %w", err)
 		}
 		fmt.Printf("Starting %s in current session...\n", agentCfg.Command)
-		return execAgent(agentCfg, "gt prime")
+		return execAgent(agentCfg, beacon)
 	}
 
 	// If inside tmux (but different session), don't switch - just inform user
diff --git a/internal/cmd/handoff.go b/internal/cmd/handoff.go
index 971b4b09..7bf7437e 100644
--- a/internal/cmd/handoff.go
+++ b/internal/cmd/handoff.go
@@ -340,19 +340,29 @@ func buildRestartCommand(sessionName string) (string, error) {
 		return "", err
 	}
 
-	// Determine GT_ROLE and BD_ACTOR values for this session
-	gtRole := sessionToGTRole(sessionName)
+	// Parse the session name to get the identity (used for GT_ROLE and beacon)
+	identity, err := session.ParseSessionName(sessionName)
+	if err != nil {
+		return "", fmt.Errorf("cannot parse session name %q: %w", sessionName, err)
+	}
+	gtRole := identity.GTRole()
+
+	// Build startup beacon for predecessor discovery via /resume
+	// Use FormatStartupNudge instead of bare "gt prime" which confuses agents
+	// The SessionStart hook handles context injection (gt prime --hook)
+	beacon := session.FormatStartupNudge(session.StartupNudgeConfig{
+		Recipient: identity.Address(),
+		Sender:    "self",
+		Topic:     "handoff",
+	})
 
 	// For respawn-pane, we:
 	// 1. cd to the right directory (role's canonical home)
 	// 2. export GT_ROLE and BD_ACTOR so role detection works correctly
 	// 3. export Claude-related env vars (not inherited by fresh shell)
-	// 4. run claude with "gt prime" as initial prompt (triggers GUPP)
+	// 4. run claude with the startup beacon (triggers immediate context loading)
 	// Use exec to ensure clean process replacement.
-	// IMPORTANT: Passing "gt prime" as argument injects it as the first prompt,
-	// which triggers the agent to execute immediately. Without this, agents
-	// wait for user input despite all GUPP prompting in hooks.
-	runtimeCmd := config.GetRuntimeCommandWithPrompt("", "gt prime")
+	runtimeCmd := config.GetRuntimeCommandWithPrompt("", beacon)
 
 	// Build environment exports - role vars first, then Claude vars
 	var exports []string
diff --git a/internal/cmd/start.go b/internal/cmd/start.go
index 9851ef0c..5c1c795a 100644
--- a/internal/cmd/start.go
+++ b/internal/cmd/start.go
@@ -19,6 +19,7 @@ import (
 	"github.com/steveyegge/gastown/internal/polecat"
 	"github.com/steveyegge/gastown/internal/refinery"
 	"github.com/steveyegge/gastown/internal/rig"
+	"github.com/steveyegge/gastown/internal/session"
 	"github.com/steveyegge/gastown/internal/style"
 	"github.com/steveyegge/gastown/internal/tmux"
 	"github.com/steveyegge/gastown/internal/witness"
@@ -277,7 +278,14 @@ func startConfiguredCrew(t *tmux.Tmux, townRoot string) {
 				if !t.IsAgentRunning(sessionID, config.ExpectedPaneCommands(agentCfg)...) {
 					// Claude has exited, restart it
 					fmt.Printf("  %s %s/%s session exists, restarting Claude...\n", style.Dim.Render("○"), r.Name, crewName)
-					claudeCmd := config.BuildCrewStartupCommand(r.Name, crewName, r.Path, "gt prime")
+					// Build startup beacon for predecessor discovery via /resume
+					address := fmt.Sprintf("%s/crew/%s", r.Name, crewName)
+					beacon := session.FormatStartupNudge(session.StartupNudgeConfig{
+						Recipient: address,
+						Sender:    "human",
+						Topic:     "restart",
+					})
+					claudeCmd := config.BuildCrewStartupCommand(r.Name, crewName, r.Path, beacon)
 					if err := t.SendKeys(sessionID, claudeCmd); err != nil {
 						fmt.Printf("  %s %s/%s restart failed: %v\n", style.Dim.Render("○"), r.Name, crewName, err)
 					} else {