single-file VS Code code:5 repro harness (Copilot Chat + Remote-SSH)

single_file_repro.sh

#!/usr/bin/env bash
set -euo pipefail

# Single-file repro harness for VS Code renderer crash code 5
# Usage:
#   bash single_file_repro.sh start [duration_seconds]
#   bash single_file_repro.sh status
#   bash single_file_repro.sh stop
#
# Optional:
#   CPU_BURST=1 bash single_file_repro.sh start 1800

cmd="${1:-start}"
duration="${2:-1800}"
root=".mre-single"
pid_file="$root/pids"

mkdir -p "$root" "notes"

osc_loop() {
  local dur="$1"
  local end=$((SECONDS + dur))
  local i=0
  while (( SECONDS < end )); do
    i=$((i + 1))
    printf '\033]0;single-mre-%06d\007' "$i"
    printf '\033]8;;https://example.com/%06d\007mre-link-%06d\033]8;;\007\n' "$i" "$i"
    printf '\033]633;A\007'
    printf 'tick=%06d ts=%(%Y-%m-%dT%H:%M:%S%z)T payload_start\n' "$i" -1
    printf '\033]633;B\007'
    for j in $(seq 1 25); do
      printf 'line=%06d.%02d payload=%08x%08x\n' "$i" "$j" "$RANDOM" "$RANDOM"
    done
    printf 'tick=%06d payload_end\n' "$i"
    sleep 0.15
  done
}

churn_loop() {
  local dur="$1"
  local end=$((SECONDS + dur))
  local i=0
  mkdir -p "$root/tmp" "$root/archive"
  local log="$root/churn.log"
  : > "$log"
  while (( SECONDS < end )); do
    i=$((i + 1))
    local f="$root/tmp/file_$i.txt"
    {
      printf 'index=%d\n' "$i"
      printf 'ts=%(%Y-%m-%dT%H:%M:%S%z)T\n' -1
      printf 'data=%08x%08x%08x\n' "$RANDOM" "$RANDOM" "$RANDOM"
    } > "$f"
    cat "$f" >> "$log"
    printf 'churn=%06d file=%s\n' "$i" "$f" >> "$log"
    if (( i % 100 == 0 )); then
      mv "$f" "$root/archive/file_$i.txt"
      find "$root/tmp" -type f | head -n 20 | xargs -I{} rm -f "{}" 2>/dev/null || true
    fi
    sleep 0.1
  done
}

cpu_loop() {
  local dur="$1"
  local end=$((SECONDS + dur))
  while (( SECONDS < end )); do
    local pids=()
    for _ in $(seq 1 8); do
      yes > /dev/null &
      pids+=("$!")
    done
    sleep 2
    kill "${pids[@]}" 2>/dev/null || true
    wait "${pids[@]}" 2>/dev/null || true
    sleep 4
  done
}

start_cmd() {
  if [ -f "$pid_file" ]; then
    echo "Already running. Use: bash single_file_repro.sh status"
    exit 1
  fi

  osc_loop "$duration" > "$root/osc.log" 2>&1 &
  p1="$!"
  churn_loop "$duration" > "$root/churn_driver.log" 2>&1 &
  p2="$!"

  p3=""
  if [ "${CPU_BURST:-0}" = "1" ]; then
    cpu_loop "$duration" > "$root/cpu_burst.log" 2>&1 &
    p3="$!"
  fi

  printf '%s %s %s\n' "$p1" "$p2" "$p3" > "$pid_file"

  cat <<EOF
Started single-file MRE load.
PIDs: $(cat "$pid_file")

Next (Copilot Chat in Agent/tool mode):
1) Run: ls -la and rg -n "tick|churn|payload" -S .
2) Run: tail -n 120 $root/churn.log
3) Edit notes/repro-note.md and re-run a search.
4) Repeat for 15-60 minutes.

Status command:
  bash single_file_repro.sh status
EOF
}

status_cmd() {
  if [ ! -f "$pid_file" ]; then
    echo "Not running."
    exit 0
  fi
  read -r p1 p2 p3 < "$pid_file"
  for p in "$p1" "$p2" "$p3"; do
    [ -z "$p" ] && continue
    if kill -0 "$p" 2>/dev/null; then
      echo "alive pid=$p"
    else
      echo "dead pid=$p"
    fi
  done
}

stop_cmd() {
  if [ ! -f "$pid_file" ]; then
    echo "Not running."
    exit 0
  fi
  read -r p1 p2 p3 < "$pid_file"
  for p in "$p1" "$p2" "$p3"; do
    [ -z "$p" ] && continue
    kill "$p" 2>/dev/null || true
  done
  rm -f "$pid_file"
  echo "Stopped."
}

case "$cmd" in
  start) start_cmd ;;
  status) status_cmd ;;
  stop) stop_cmd ;;
  *)
    echo "Unknown command: $cmd"
    echo "Usage: bash single_file_repro.sh {start [duration]|status|stop}"
    exit 1
    ;;
esac