diff --git a/internal/cmd/prime.go b/internal/cmd/prime.go
index acdd35af2b..bd3d002698 100644
--- a/internal/cmd/prime.go
+++ b/internal/cmd/prime.go
@@ -390,7 +390,14 @@ func setupPrimeSession(ctx RoleContext, roleInfo RoleInfo) error {
 		ensureBeadsRedirect(ctx)
 	}
 	repairSessionEnv(ctx, roleInfo)
-	emitSessionEvent(ctx)
+	// Only emit session_start when gt prime is running as a SessionStart or
+	// PreCompact hook. Bare gt prime calls (e.g. an agent reading another
+	// agent's context) must not emit session_start — doing so logs a spurious
+	// event with the target agent's persisted session_id, which pollutes the
+	// event stream and can confuse gt seance discovery.
+	if primeHookMode {
+		emitSessionEvent(ctx)
+	}
 	return nil
 }