Codexer: shell helper for codex that pipes a startup checklist plus the last Codex conversation into codex. Supports --resume, --limit, --id, --index, and --list. Finds session JSONL under ~/.codex/sessions, orders by timestamp, prints User/Assistant lines.

codexer.sh

# --- Place below in .zshrc ---------

# === Self-contained codexer with resume seed builder ===


# --- codexer: simple conversation loader for the Codex CLI --------------------
# Features:
#   --resume          Append the last conversation (user + assistant) to the seed
#   --limit N         Include only the last N lines of that conversation
#   --id SESSION_ID   Resume a specific session id (instead of the most recent)
#   --index N         Resume the Nth most-recent session id (1 = newest)
#   --list [N]        List the N most-recent session ids (default 20) and exit
#
# Behavior:
#   - By default, loads the *entire* last conversation (Claude-like).
#   - Falls back gracefully if jq or logs are missing.
#   - All other args are passed through to the `codex` CLI.

# --- helpers ------------------------------------------------------------------

# Print recent unique session_ids from history.jsonl, newest first (one per line)
_codex_recent_session_ids() {
  local history_file="$HOME/.codex/history.jsonl"
  command -v jq >/dev/null 2>&1 || return 0
  [[ -s "$history_file" ]] || return 0

  if command -v tac >/dev/null 2>&1; then
    # Reverse order after extracting IDs; unique while preserving order
    jq -r '.session_id // empty' "$history_file" \
      | tac | awk 'NF && !seen[$0]++'
  else
    # Portable reverse if tac unavailable
    awk '{ buf[NR]=$0 } END { for (i=NR; i>0; i--) print buf[i] }' "$history_file" \
      | jq -Rr 'fromjson? | .session_id // empty' \
      | awk 'NF && !seen[$0]++'
  fi
}

# Return the newest session file (.jsonl) under ~/.codex/sessions containing $1
_codex_find_session_file_for_id() {
  local sid="$1" root="$HOME/.codex/sessions"
  [[ -n "$sid" ]] || return 1
  find "$root" -type f -name '*.jsonl' -print0 2>/dev/null \
    | xargs -0 grep -l -- "$sid" 2>/dev/null \
    | sort | tail -n 1
}

# Emit a labeled transcript (User:/Assistant:) ordered by timestamp for a file
_codex_transcript_for_file() {
  local file="$1"
  [[ -f "$file" ]] || return 1
  jq -r '
    select(.type=="message" and (.role=="user" or .role=="assistant")) as $m
    | [ ($m.timestamp // $m.ts // 0)
      , $m.role
      , ( ($m.content[]? | select(.text? and (.text|type=="string")) | .text)
          // ($m.text // "") )
      ]
    | @tsv
  ' "$file" \
  | sort -n \
  | awk -F'\t' '{
      role=$2; text=$3; gsub("\r","",text);
      if (role=="user")      print "User: " text;
      else if (role=="assistant") print "Assistant: " text;
    }'
}

# --- main ---------------------------------------------------------------------

codexer() {
  emulate -L zsh
  setopt pipefail

  # Flags we handle; everything else is passed to codex
  local resume=0 limit="" id="" index=""
  local list=0 list_count=20
  local -a passthrough=()

  while [[ $# -gt 0 ]]; do
    case "$1" in
      --resume) resume=1 ;;
      --limit)  shift; limit="${1:-}" ;;
      --id)     shift; id="${1:-}" ;;
      --index)  shift; index="${1:-}" ;;
      --list)   list=1; if [[ -n "${2:-}" && "$2" == <-> ]]; then list_count="$2"; shift; fi ;;
      --) shift; while [[ $# -gt 0 ]]; do passthrough+=("$1"); shift; done; break ;;
      *)  passthrough+=("$1") ;;
    esac
    shift || true
  done

  # Quick list mode
  if (( list )); then
    local n=0
    _codex_recent_session_ids | while IFS= read -r sid; do
      (( ++n ))
      printf "%2d. %s\n" "$n" "$sid"
      [[ $n -ge $list_count ]] && break
    done
    return 0
  fi

  # Default startup seed (your checklist)
  local seed=$'1. Run '\''source .venv/bin/activate && set -a && [ -f .env ] && source .env'\''\n2. Activate the current dir as project using serena.\n3. Peruse the README.md and the pyproject.toml.'

  # Optionally append last session transcript
  if (( resume )); then
    if ! command -v jq >/dev/null 2>&1; then
      print -u2 -- "Warning: jq not found; skipping --resume."
    else
      # Decide which session_id to use
      local sid="$id"
      if [[ -z "$sid" ]]; then
        if [[ -n "$index" && "$index" == <-> ]]; then
          sid=$(_codex_recent_session_ids | sed -n "${index}p")
        else
          sid=$(_codex_recent_session_ids | head -n 1)
        fi
      fi

      if [[ -z "$sid" ]]; then
        print -u2 -- "No previous session_id found; skipping --resume."
      else
        local file; file=$(_codex_find_session_file_for_id "$sid")
        if [[ -z "$file" ]]; then
          print -u2 -- "No session file found for session_id=$sid."
        else
          local transcript; transcript=$(_codex_transcript_for_file "$file")
          if [[ -n "$limit" && -n "$transcript" ]]; then
            transcript=$(printf "%s\n" "$transcript" | tail -n "$limit")
          fi
          if [[ -n "$transcript" ]]; then
            seed+=$'\n\n=== Last Session Transcript ===\n'"$transcript"
          else
            print -u2 -- "No user/assistant messages found in: $file"
          fi
        fi
      fi
    fi
  fi

  # Pipe seed into codex (stdin). Add your usual codex flags to $passthrough.
  printf "%b\n" "$seed" | codex - "${passthrough[@]}"
}