feat: add interactive 2-user lab environment + fix requirements.txt encoding

- lab/setup-lab.sh: automated tmux setup with server + 2 chat clients
  Supports --no-tls, --password, --port, --user1/--user2, --teardown
  Auto-installs missing pip dependencies, verifies port availability,
  waits for server health before connecting clients
- lab/README.md: usage docs and keyboard shortcuts
- requirements.txt: fixed UTF-16 encoding to UTF-8, cleaned pinned versions

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lab/README.md

@@ -0,0 +1,55 @@
+# cmd-chat Lab
+
+Interactive 2-user test environment using tmux. Spins up a server and two chat clients side-by-side so you can send messages between them.
+
+## Quick Start
+
+```bash
+# Default (TLS, password: labtest)
+./lab/setup-lab.sh
+
+# Plain HTTP (local testing)
+./lab/setup-lab.sh --no-tls
+
+# Custom password and port
+./lab/setup-lab.sh --password mysecret --port 5000
+
+# Custom usernames
+./lab/setup-lab.sh --user1 charlie --user2 dave
+```
+
+## Attach & Navigate
+
+```bash
+tmux attach -t cmd-chat-lab
+```
+
+| Key | Action |
+|-----|--------|
+| `Ctrl+B` then arrow keys | Switch between panes |
+| `Ctrl+B` then `z` | Zoom/unzoom current pane |
+| `q` | Disconnect from chat |
+| `Ctrl+C` in server pane | Stop server |
+
+## Teardown
+
+```bash
+./lab/setup-lab.sh --teardown
+```
+
+## Layout
+
+```
+┌──────────── SERVER (127.0.0.1:4000) ─────────────┐
+│ Sanic running, admin token displayed here        │
+├──────── alice ───────┬──────── bob ──────────────┤
+│ Type messages here   │ Type messages here        │
+│ and hit Enter        │ and hit Enter             │
+└──────────────────────┴───────────────────────────┘
+```
+
+## Requirements
+
+- Python 3.10+
+- tmux 3.0+
+- All Python deps from `requirements.txt` (auto-installed if missing)

lab/setup-lab.sh

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+#!/usr/bin/env bash
+#
+# cmd-chat Lab — Interactive 2-user encrypted chat test environment
+#
+# Usage:
+#   ./lab/setup-lab.sh                    # TLS mode (default, auto-generates self-signed cert)
+#   ./lab/setup-lab.sh --no-tls           # Plain HTTP mode (local testing only)
+#   ./lab/setup-lab.sh --password secret  # Set room password (default: prompted or "labtest")
+#   ./lab/setup-lab.sh --port 5000        # Custom port (default: 4000)
+#   ./lab/setup-lab.sh --teardown         # Kill existing lab session
+#
+# Attach to the running lab:
+#   tmux attach -t cmd-chat-lab
+#
+# Pane navigation:
+#   Ctrl+B then arrow keys   — switch between panes
+#   Ctrl+B then z            — zoom/unzoom current pane
+#   Type 'q' in a chat pane  — disconnect that user
+#   Ctrl+C in server pane    — stop server
+#
+
+set -euo pipefail
+
+# ─── Configuration ───────────────────────────────────────────────────────────
+
+SESSION="cmd-chat-lab"
+PORT="${PORT:-4000}"
+PASSWORD=""
+NO_TLS=false
+TEARDOWN=false
+USER1="alice"
+USER2="bob"
+
+# ─── Parse Arguments ────────────────────────────────────────────────────────
+
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --no-tls)     NO_TLS=true; shift ;;
+        --password)   PASSWORD="$2"; shift 2 ;;
+        --port)       PORT="$2"; shift 2 ;;
+        --user1)      USER1="$2"; shift 2 ;;
+        --user2)      USER2="$2"; shift 2 ;;
+        --teardown)   TEARDOWN=true; shift ;;
+        -h|--help)
+            head -20 "$0" | grep '^#' | sed 's/^# \?//'
+            exit 0
+            ;;
+        *)
+            echo "Unknown option: $1" >&2
+            exit 1
+            ;;
+    esac
+done
+
+# ─── Resolve project root ───────────────────────────────────────────────────
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+
+# ─── Teardown ────────────────────────────────────────────────────────────────
+
+if $TEARDOWN; then
+    if tmux has-session -t "$SESSION" 2>/dev/null; then
+        tmux kill-session -t "$SESSION"
+        echo "Killed session: $SESSION"
+    else
+        echo "No session to kill."
+    fi
+    exit 0
+fi
+
+# ─── Pre-flight checks ──────────────────────────────────────────────────────
+
+check_command() {
+    if ! command -v "$1" &>/dev/null; then
+        echo "ERROR: $1 not found. Install it first." >&2
+        exit 1
+    fi
+}
+
+check_command tmux
+check_command python3
+
+# Check dependencies
+echo "Checking Python dependencies..."
+MISSING=()
+for pkg in sanic srp cryptography websockets rich requests; do
+    if ! python3 -c "import $pkg" 2>/dev/null; then
+        MISSING+=("$pkg")
+    fi
+done
+
+if [[ ${#MISSING[@]} -gt 0 ]]; then
+    echo "Installing missing packages: ${MISSING[*]}"
+    python3 -m pip install -r "$PROJECT_ROOT/requirements.txt" --quiet 2>/dev/null
+    echo "Dependencies installed."
+else
+    echo "All dependencies OK."
+fi
+
+# Check if port is available
+if ss -tlnp 2>/dev/null | grep -q ":${PORT} " || lsof -i ":${PORT}" &>/dev/null; then
+    echo "ERROR: Port $PORT is already in use." >&2
+    echo "  Try: $0 --port 4001" >&2
+    exit 1
+fi
+
+# ─── Password resolution ────────────────────────────────────────────────────
+
+if [[ -z "$PASSWORD" ]]; then
+    if [[ -n "${CMD_CHAT_PASSWORD:-}" ]]; then
+        PASSWORD="$CMD_CHAT_PASSWORD"
+    else
+        PASSWORD="labtest"
+        echo "Using default password: $PASSWORD"
+    fi
+fi
+export CMD_CHAT_PASSWORD="$PASSWORD"
+
+# ─── Kill existing session if any ────────────────────────────────────────────
+
+if tmux has-session -t "$SESSION" 2>/dev/null; then
+    echo "Killing existing $SESSION session..."
+    tmux kill-session -t "$SESSION"
+    sleep 1
+fi
+
+# ─── Build TLS flags ────────────────────────────────────────────────────────
+
+SERVER_FLAGS=""
+CLIENT_FLAGS=""
+if $NO_TLS; then
+    SERVER_FLAGS="--no-tls"
+    CLIENT_FLAGS="--no-tls"
+    PROTO="http"
+else
+    CLIENT_FLAGS="--insecure"
+    PROTO="https"
+fi
+
+# ─── Create tmux session ────────────────────────────────────────────────────
+
+echo ""
+echo "Setting up cmd-chat lab..."
+echo "  Server:  $PROTO://127.0.0.1:$PORT"
+echo "  Users:   $USER1, $USER2"
+echo "  TLS:     $( $NO_TLS && echo 'disabled' || echo 'enabled (self-signed)' )"
+echo ""
+
+# Pane 1: Server (top)
+tmux new-session -d -s "$SESSION" -n chat -c "$PROJECT_ROOT" -x 200 -y 50
+
+# Pane 2: Client alice (bottom-left)
+tmux split-window -v -t "$SESSION:chat" -p 75 -c "$PROJECT_ROOT" 2>/dev/null || \
+    tmux split-window -v -t "$SESSION:chat" -c "$PROJECT_ROOT"
+
+# Pane 3: Client bob (bottom-right)
+tmux split-window -h -t "$SESSION:chat" -c "$PROJECT_ROOT" 2>/dev/null || true
+
+# Get pane IDs
+PANES=($(tmux list-panes -t "$SESSION:chat" -F '#{pane_id}'))
+SERVER_PANE="${PANES[0]}"
+ALICE_PANE="${PANES[1]}"
+BOB_PANE="${PANES[2]}"
+
+# Label panes
+tmux select-pane -t "$SERVER_PANE" -T "SERVER ($PROTO://127.0.0.1:$PORT)"
+tmux select-pane -t "$ALICE_PANE" -T "$USER1"
+tmux select-pane -t "$BOB_PANE" -T "$USER2"
+tmux set -t "$SESSION" pane-border-format " #{pane_title} "
+tmux set -t "$SESSION" pane-border-status top
+
+# Resize server pane smaller
+tmux resize-pane -t "$SERVER_PANE" -y 10
+
+# ─── Start server ───────────────────────────────────────────────────────────
+
+tmux send-keys -t "$SERVER_PANE" \
+    "cd '$PROJECT_ROOT' && CMD_CHAT_PASSWORD='$PASSWORD' python3 cmd_chat.py serve 127.0.0.1 $PORT $SERVER_FLAGS" Enter
+
+# Wait for server to be ready
+echo -n "Waiting for server"
+for i in $(seq 1 15); do
+    if $NO_TLS; then
+        curl -sf "http://127.0.0.1:$PORT/health" &>/dev/null && break
+    else
+        curl -sfk "https://127.0.0.1:$PORT/health" &>/dev/null && break
+    fi
+    echo -n "."
+    sleep 1
+done
+echo " ready!"
+
+# ─── Connect clients ────────────────────────────────────────────────────────
+
+tmux send-keys -t "$ALICE_PANE" \
+    "cd '$PROJECT_ROOT' && CMD_CHAT_PASSWORD='$PASSWORD' python3 cmd_chat.py connect 127.0.0.1 $PORT $USER1 $CLIENT_FLAGS" Enter
+
+sleep 2
+
+tmux send-keys -t "$BOB_PANE" \
+    "cd '$PROJECT_ROOT' && CMD_CHAT_PASSWORD='$PASSWORD' python3 cmd_chat.py connect 127.0.0.1 $PORT $USER2 $CLIENT_FLAGS" Enter
+
+sleep 2
+
+# ─── Verify ─────────────────────────────────────────────────────────────────
+
+ALICE_OUT=$(tmux capture-pane -t "$ALICE_PANE" -p 2>/dev/null)
+BOB_OUT=$(tmux capture-pane -t "$BOB_PANE" -p 2>/dev/null)
+
+if echo "$ALICE_OUT" | grep -q "Online:" && echo "$BOB_OUT" | grep -q "Online:"; then
+    echo ""
+    echo "Lab is running! Both users connected."
+    echo ""
+    echo "  Attach:    tmux attach -t $SESSION"
+    echo "  Teardown:  $0 --teardown"
+    echo ""
+    echo "  Switch panes:  Ctrl+B then arrow keys"
+    echo "  Zoom pane:     Ctrl+B then z"
+    echo "  Quit chat:     type 'q' in a chat pane"
+    echo ""
+else
+    echo ""
+    echo "WARNING: One or both clients may not have connected."
+    echo "Attach and check: tmux attach -t $SESSION"
+fi