refactor: use delegated python binary in script execution and update resolution logic to prioritize virtual environments

.agents/skills/lib.sh

@@ -633,7 +633,9 @@ env_python() {
         ;;
     esac
   done
-  env "${envs[@]}" python3 - "$@"
+  local pybin
+  pybin="$(_delegate_py_bin)"
+  env "${envs[@]}" "$pybin" - "$@"
 }
 
 # ---------------------------------------------------------------------------
@@ -691,7 +693,9 @@ atomic_dump_yaml() {
     esac
   done
   local mutation; mutation="$(cat)"
-  env "${envs[@]}" AGENT_SESSIONS_MUTATION="$mutation" python3 - <<'PYEOF'
+  local pybin
+  pybin="$(_delegate_py_bin)"
+  env "${envs[@]}" AGENT_SESSIONS_MUTATION="$mutation" "$pybin" - <<'PYEOF'
 import os, sys, tempfile, shutil, glob, subprocess, json, sqlite3
 from datetime import datetime, timezone
 import yaml
@@ -1362,10 +1366,14 @@ PYEOF
 
 # _delegate_py_bin — echo the virtualenv python (walk up from .agents/skills/), else python3.
 _delegate_py_bin() {
-  # Return cached result if available (shell variable, not exported — avoids cross-workspace pollution)
+  # Return cached result if available
   if [ -n "${AGENT_PYTHON_BIN:-}" ] && [ -x "$AGENT_PYTHON_BIN" ]; then
     printf '%s\n' "$AGENT_PYTHON_BIN"; return 0
   fi
+  if [ -n "${VIRTUAL_ENV:-}" ] && [ -x "$VIRTUAL_ENV/bin/python" ]; then
+    AGENT_PYTHON_BIN="$VIRTUAL_ENV/bin/python"
+    printf '%s\n' "$AGENT_PYTHON_BIN"; return 0
+  fi
   local d
   d="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
   while [ "$d" != "/" ] && [ -n "$d" ]; do