feat(mux): implement onboarding prompt initialization, 4-tier UUID validation, and TUI 1:1 cross-matching

.agents/skills/multi-agent-mux-resume/scripts/resume_session.sh

@@ -6,7 +6,11 @@ source "$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)/lib.sh"
 
 usage() {
   cat <<EOF
-Usage: $0 --workspace <path> --agent <claude|agy|hermes|cline> --session <name>
+Usage: $0 --workspace <path> --agent <claude|agy|hermes|cline> --session <name> [--dry-run]
+
+Options:
+  --dry-run   Simulates resume flow (resolves binary, environment, isolation) without writing
+              any updates to YAML or DB. Safe to execute inside active write transactions.
 EOF
 }
 
@@ -14,11 +18,14 @@ WORKSPACE=""
 AGENT=""
 SESSION_NAME=""
 
+DRY_RUN=0
+
 while [ $# -gt 0 ]; do
   case "$1" in
     --workspace) WORKSPACE="$2"; shift 2 ;;
     --agent)     AGENT="$2";     shift 2 ;;
     --session)   SESSION_NAME="$2"; shift 2 ;;
+    --dry-run)   DRY_RUN=1; shift ;;
     -h|--help)   usage; exit 0 ;;
     *) echo "ERROR: unknown arg: $1" >&2; exit 2 ;;
   esac
@@ -42,6 +49,10 @@ export HERDR_SERVER_NAME
 
 # 2. If herdr is alive, print warning or attach.
 if herdr has-session -t "$SESSION_NAME" 2>/dev/null; then
+  if [ "${DRY_RUN:-0}" = "1" ]; then
+    echo "[dry-run] herdr '$SESSION_NAME' already running — nothing to validate"
+    exit 0
+  fi
   echo "herdr '$SESSION_NAME' already running."
   # Just update YAML to make sure it's set to running
   bash "$(dirname "${BASH_SOURCE[0]}")/update_yaml_resumed.sh" \
@@ -111,6 +122,7 @@ case "$AGENT" in
   agy)    CMD_FULL="${RESOLVED_BIN} --dangerously-skip-permissions --conversation $UUID" ;;
   hermes) CMD_FULL="${RESOLVED_BIN} --resume $UUID" ;;
   cline)  CMD_FULL="${RESOLVED_BIN} -i --id $UUID" ;;
+  *)      echo "ERROR: unsupported agent: $AGENT" >&2; exit 2 ;;
 esac
 
 # Prepend env prefix and append command args (T4)
@@ -121,6 +133,30 @@ if [ -n "$ISO_ARGS" ]; then
   CMD_FULL="$CMD_FULL $ISO_ARGS"
 fi
 
+# Validate isolation root if it was configured
+if [ -n "$ISO_ROOT" ] && [ ! -d "$ISO_ROOT" ]; then
+  echo "ERROR: Isolation root directory does not exist: $ISO_ROOT" >&2
+  exit 1
+fi
+
+# Validate binary exists and is executable
+if [ -f "$RESOLVED_BIN" ] || [[ "$RESOLVED_BIN" == /* ]] || [[ "$RESOLVED_BIN" == ~/* ]]; then
+  if [ ! -x "$RESOLVED_BIN" ]; then
+    echo "ERROR: Agent binary is not executable: $RESOLVED_BIN" >&2
+    exit 1
+  fi
+else
+  if ! command -v "$RESOLVED_BIN" >/dev/null 2>&1; then
+    echo "ERROR: Agent binary not found in PATH: $RESOLVED_BIN" >&2
+    exit 1
+  fi
+fi
+
+if [ "${DRY_RUN:-0}" = "1" ]; then
+  echo "[dry-run] would spawn: $CMD_FULL"
+  exit 0
+fi
+
 # 4. Spawn new agent session (delegates to herdr translation shim)
 _herdr new-session -d -s "$SESSION_NAME" -c "$WORKSPACE" "$CMD_FULL"
 if [ "$AGENT" = "claude" ]; then