feat(client): v2 CLI binary over SDK with simplified commands

Add v2_main.rs and v2_commands.rs as thin wrappers over QpqClient from
quicproquo-sdk. Activated via --features v2 (feature-gated so v1 main.rs
remains the default). Includes auto-server-launch, clap-based command
surface (register-user, login, whoami, health, resolve, dm, group,
devices), and ClientConfig-based connection setup. MLS-dependent commands
(send, recv, group create/invite) print stubs pointing to the REPL.

crates/quicproquo-client/src/client/v2_repl.rs

@@ -0,0 +1,3 @@
+//! v2 REPL — interactive mode over the SDK.
+//!
+//! Placeholder module; full implementation will replace the v1 repl.

crates/quicproquo-client/src/lib.rs

@@ -20,6 +20,8 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use zeroize::Zeroizing;
 
 pub mod client;
+#[cfg(feature = "v2")]
+pub mod v2_commands;
 
 pub use client::commands::{
     cmd_chat, cmd_check_key, cmd_create_group, cmd_demo_group, cmd_export, cmd_export_verify,

crates/quicproquo-client/src/main.rs

@@ -1,20 +1,35 @@
 //! quicproquo CLI client.
 
+// ── v2 feature gate: when compiled with --features v2, use the SDK-based CLI.
+#[cfg(feature = "v2")]
+mod v2_commands;
+#[cfg(feature = "v2")]
+mod v2_main;
+
+#[cfg(feature = "v2")]
+fn main() {
+    v2_main::main();
+}
+
+// ── v1 CLI (default) ─────────────────────────────────────────────────────────
+#[cfg(not(feature = "v2"))]
 use std::path::{Path, PathBuf};
-
+#[cfg(not(feature = "v2"))]
 use anyhow::Context;
+#[cfg(not(feature = "v2"))]
 use clap::{Parser, Subcommand};
-
+#[cfg(not(feature = "v2"))]
 use quicproquo_client::{
     cmd_chat, cmd_check_key, cmd_create_group, cmd_demo_group, cmd_export, cmd_export_verify,
     cmd_fetch_key, cmd_health, cmd_invite, cmd_join, cmd_login, cmd_ping, cmd_recv, cmd_register,
     cmd_register_state, cmd_refresh_keypackage, cmd_register_user, cmd_send, cmd_whoami,
     init_auth, run_repl, set_insecure_skip_verify, ClientAuth,
 };
-#[cfg(feature = "tui")]
+#[cfg(all(feature = "tui", not(feature = "v2")))]
 use quicproquo_client::client::tui::run_tui;
 
 // ── CLI ───────────────────────────────────────────────────────────────────────
+#[cfg(not(feature = "v2"))]
 
 #[derive(Debug, Parser)]
 #[command(name = "qpq", about = "quicproquo CLI client", version)]
@@ -90,6 +105,7 @@ struct Args {
     command: Option<Command>,
 }
 
+#[cfg(not(feature = "v2"))]
 #[derive(Debug, Subcommand)]
 enum Command {
     /// Register a new user via OPAQUE (password never leaves the client).
@@ -424,7 +440,7 @@ enum Command {
 }
 
 // ── Helpers ───────────────────────────────────────────────────────────────────
-
+#[cfg(not(feature = "v2"))]
 /// Returns `qpq-{username}.bin` when `state` is still at the default
 /// (`qpq-state.bin`) and a username has been provided. Otherwise returns
 /// `state` unchanged. This lets `qpq --username alice` automatically isolate
@@ -440,7 +456,7 @@ fn derive_state_path(state: PathBuf, username: Option<&str>) -> PathBuf {
 
 // ── Playbook execution ───────────────────────────────────────────────────────
 
-#[cfg(feature = "playbook")]
+#[cfg(all(feature = "playbook", not(feature = "v2")))]
 async fn run_playbook(
     playbook_path: &Path,
     state: &Path,
@@ -511,6 +527,7 @@ async fn run_playbook(
 
 // ── Entry point ───────────────────────────────────────────────────────────────
 
+#[cfg(not(feature = "v2"))]
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     // Install the rustls crypto provider before any TLS operations.

crates/quicproquo-client/src/v2_commands.rs

@@ -0,0 +1,128 @@
+//! v2 CLI command implementations — thin wrappers over the SDK.
+
+use quicproquo_sdk::client::QpqClient;
+use quicproquo_sdk::error::SdkError;
+
+/// Register a new user account via OPAQUE.
+pub async fn cmd_register_user(
+    client: &mut QpqClient,
+    username: &str,
+    password: &str,
+) -> Result<(), SdkError> {
+    client.register(username, password).await?;
+    let key = client.identity_key().unwrap_or_default();
+    println!("registered user: {username}");
+    println!("identity key  : {}", hex::encode(key));
+    Ok(())
+}
+
+/// Log in via OPAQUE and print session info.
+pub async fn cmd_login(
+    client: &mut QpqClient,
+    username: &str,
+    password: &str,
+) -> Result<(), SdkError> {
+    client.login(username, password).await?;
+    println!("logged in as: {username}");
+    if let Some(key) = client.identity_key() {
+        println!("identity key: {}", hex::encode(key));
+    }
+    Ok(())
+}
+
+/// Print local identity information.
+pub fn cmd_whoami(client: &QpqClient) {
+    match client.username() {
+        Some(u) => println!("username    : {u}"),
+        None => println!("username    : (not logged in)"),
+    }
+    match client.identity_key() {
+        Some(k) => println!("identity key: {}", hex::encode(k)),
+        None => println!("identity key: (none)"),
+    }
+    println!("connected   : {}", client.is_connected());
+    println!("authenticated: {}", client.is_authenticated());
+}
+
+/// Health check — connect to the server and report status.
+pub async fn cmd_health(client: &mut QpqClient) -> Result<(), SdkError> {
+    let start = std::time::Instant::now();
+    // The SDK connect() already establishes a QUIC connection.
+    // If we're already connected, just report success.
+    if !client.is_connected() {
+        client.connect().await?;
+    }
+    let rtt_ms = start.elapsed().as_millis();
+    println!("status : ok");
+    println!("rtt    : {rtt_ms}ms");
+    Ok(())
+}
+
+/// Resolve a username to its identity key.
+pub async fn cmd_resolve(client: &mut QpqClient, username: &str) -> Result<(), SdkError> {
+    let rpc = client.rpc()?;
+    match quicproquo_sdk::users::resolve_user(rpc, username).await? {
+        Some(key) => {
+            println!("{username} -> {}", hex::encode(&key));
+        }
+        None => {
+            println!("{username}: not found");
+        }
+    }
+    Ok(())
+}
+
+/// List registered devices.
+pub async fn cmd_devices_list(client: &mut QpqClient) -> Result<(), SdkError> {
+    let rpc = client.rpc()?;
+    let devices = quicproquo_sdk::devices::list_devices(rpc).await?;
+    if devices.is_empty() {
+        println!("no devices registered");
+    } else {
+        println!("{:<36}  {:<20}  {}", "DEVICE ID", "NAME", "REGISTERED AT");
+        for d in &devices {
+            println!(
+                "{:<36}  {:<20}  {}",
+                hex::encode(&d.device_id),
+                d.device_name,
+                d.registered_at,
+            );
+        }
+    }
+    Ok(())
+}
+
+/// Register a new device.
+pub async fn cmd_devices_register(
+    client: &mut QpqClient,
+    device_id: &str,
+    device_name: &str,
+) -> Result<(), SdkError> {
+    let rpc = client.rpc()?;
+    let id_bytes = hex::decode(device_id)
+        .map_err(|e| SdkError::Other(anyhow::anyhow!("invalid device_id hex: {e}")))?;
+    let was_new = quicproquo_sdk::devices::register_device(rpc, &id_bytes, device_name).await?;
+    if was_new {
+        println!("device registered: {device_name}");
+    } else {
+        println!("device already registered: {device_name}");
+    }
+    Ok(())
+}
+
+/// Revoke a device.
+pub async fn cmd_devices_revoke(
+    client: &mut QpqClient,
+    device_id: &str,
+) -> Result<(), SdkError> {
+    let rpc = client.rpc()?;
+    let id_bytes = hex::decode(device_id)
+        .map_err(|e| SdkError::Other(anyhow::anyhow!("invalid device_id hex: {e}")))?;
+    let revoked = quicproquo_sdk::devices::revoke_device(rpc, &id_bytes).await?;
+    if revoked {
+        println!("device revoked: {device_id}");
+    } else {
+        println!("device not found: {device_id}");
+    }
+    Ok(())
+}

crates/quicproquo-client/src/v2_main.rs

@@ -0,0 +1,484 @@
+//! v2 CLI entry point — thin shell over `quicproquo_sdk::QpqClient`.
+//!
+//! Activated via `--features v2`. Replaces the v1 Cap'n Proto RPC main
+//! with a simplified command surface backed by the SDK.
+
+use std::path::{Path, PathBuf};
+use std::process::Command as ProcessCommand;
+use std::time::Duration;
+
+use anyhow::Context;
+use clap::{Parser, Subcommand};
+
+use quicproquo_sdk::client::QpqClient;
+use quicproquo_sdk::config::ClientConfig;
+
+use crate::v2_commands;
+
+// ── CLI ───────────────────────────────────────────────────────────────────────
+
+#[derive(Debug, Parser)]
+#[command(name = "qpq", about = "quicproquo CLI client (v2)", version)]
+struct Args {
+    /// Server address (host:port).
+    #[arg(long, global = true, default_value = "127.0.0.1:7000", env = "QPQ_SERVER")]
+    server: String,
+
+    /// TLS server name (must match certificate SAN).
+    #[arg(long, global = true, default_value = "localhost", env = "QPQ_SERVER_NAME")]
+    server_name: String,
+
+    /// Path to local conversation database.
+    #[arg(long, global = true, default_value = "conversations.db", env = "QPQ_CONV_DB")]
+    db_path: PathBuf,
+
+    /// Password for encrypting the local database.
+    #[arg(long, global = true, env = "QPQ_DB_PASSWORD")]
+    db_password: Option<String>,
+
+    /// Path to the client state file (identity key, MLS state).
+    #[arg(long, global = true, default_value = "qpq-state.bin", env = "QPQ_STATE")]
+    state: PathBuf,
+
+    /// DANGER: Skip TLS certificate verification. Development only.
+    #[arg(
+        long = "danger-accept-invalid-certs",
+        global = true,
+        env = "QPQ_DANGER_ACCEPT_INVALID_CERTS"
+    )]
+    danger_accept_invalid_certs: bool,
+
+    /// Do not auto-start a local qpq-server.
+    #[arg(long, global = true, env = "QPQ_NO_SERVER")]
+    no_server: bool,
+
+    #[command(subcommand)]
+    command: Cmd,
+}
+
+#[derive(Debug, Subcommand)]
+enum Cmd {
+    /// Register a new user via OPAQUE (password never leaves the client).
+    RegisterUser {
+        /// Username for the new account.
+        #[arg(long)]
+        username: String,
+        /// Password (used in OPAQUE PAKE; server never sees it).
+        #[arg(long)]
+        password: String,
+    },
+
+    /// Log in via OPAQUE and receive a session token.
+    Login {
+        #[arg(long)]
+        username: String,
+        #[arg(long)]
+        password: String,
+    },
+
+    /// Show local identity info.
+    Whoami,
+
+    /// Server health check.
+    Health,
+
+    /// Send a message to a conversation.
+    Send {
+        /// Conversation name (group name or DM peer username).
+        #[arg(long)]
+        to: String,
+        /// Message text.
+        #[arg(long)]
+        msg: String,
+    },
+
+    /// Receive pending messages from a conversation.
+    Recv {
+        /// Conversation name.
+        #[arg(long)]
+        from: String,
+    },
+
+    /// Start or resume a DM with a user.
+    Dm {
+        /// Peer username.
+        username: String,
+    },
+
+    /// Group management commands.
+    Group {
+        #[command(subcommand)]
+        action: GroupCmd,
+    },
+
+    /// Resolve a username to its identity key.
+    Resolve {
+        /// Username to look up.
+        username: String,
+    },
+
+    /// Device management.
+    Devices {
+        #[command(subcommand)]
+        action: DevicesCmd,
+    },
+}
+
+#[derive(Debug, Subcommand)]
+enum GroupCmd {
+    /// Create a new group.
+    Create {
+        /// Group name.
+        name: String,
+    },
+    /// Invite a user to a group.
+    Invite {
+        /// Group name.
+        #[arg(long)]
+        group: String,
+        /// Username to invite.
+        #[arg(long)]
+        user: String,
+    },
+}
+
+#[derive(Debug, Subcommand)]
+enum DevicesCmd {
+    /// List registered devices.
+    List,
+    /// Register a new device.
+    Register {
+        /// Device ID (hex).
+        #[arg(long)]
+        id: String,
+        /// Human-readable device name.
+        #[arg(long)]
+        name: String,
+    },
+    /// Revoke a device.
+    Revoke {
+        /// Device ID (hex).
+        #[arg(long)]
+        id: String,
+    },
+}
+
+// ── Auto-server launch ───────────────────────────────────────────────────────
+
+/// RAII guard that kills an auto-started server process on drop.
+struct ServerGuard(Option<std::process::Child>);
+
+impl Drop for ServerGuard {
+    fn drop(&mut self) {
+        if let Some(ref mut child) = self.0 {
+            let _ = child.kill();
+            let _ = child.wait();
+        }
+    }
+}
+
+/// Find the `qpq-server` binary: same directory as current exe, then PATH.
+fn find_server_binary() -> Option<PathBuf> {
+    if let Ok(exe) = std::env::current_exe() {
+        let sibling = exe.with_file_name("qpq-server");
+        if sibling.exists() {
+            return Some(sibling);
+        }
+    }
+    std::env::var_os("PATH").and_then(|paths| {
+        std::env::split_paths(&paths)
+            .map(|dir| dir.join("qpq-server"))
+            .find(|p| p.exists())
+    })
+}
+
+/// Try a QUIC health probe to the server address.
+async fn probe_server(server_addr: &str) -> bool {
+    use std::net::ToSocketAddrs;
+    let addr = match server_addr.to_socket_addrs() {
+        Ok(mut addrs) => match addrs.next() {
+            Some(a) => a,
+            None => return false,
+        },
+        Err(_) => return false,
+    };
+    // Simple TCP probe — if the port is open, the server is likely running.
+    tokio::net::TcpStream::connect(addr)
+        .await
+        .is_ok()
+}
+
+/// Start a local qpq-server if one isn't already running.
+/// Returns a guard that kills the child on drop (if we started one).
+async fn ensure_server_running(
+    server_addr: &str,
+    data_dir: &Path,
+    no_server: bool,
+) -> anyhow::Result<ServerGuard> {
+    if no_server {
+        return Ok(ServerGuard(None));
+    }
+
+    if probe_server(server_addr).await {
+        return Ok(ServerGuard(None));
+    }
+
+    let binary = find_server_binary().ok_or_else(|| {
+        anyhow::anyhow!(
+            "server at {server_addr} is not reachable and qpq-server binary not found; \
+             start a server manually or install qpq-server"
+        )
+    })?;
+
+    let cert_path = data_dir.join("server-cert.der");
+    let key_path = data_dir.join("server-key.der");
+
+    eprintln!("starting server on {server_addr}...");
+
+    let child = ProcessCommand::new(&binary)
+        .args([
+            "--allow-insecure-auth",
+            "--listen",
+            server_addr,
+            "--tls-cert",
+            &cert_path.to_string_lossy(),
+            "--tls-key",
+            &key_path.to_string_lossy(),
+        ])
+        .stdout(std::process::Stdio::null())
+        .stderr(std::process::Stdio::null())
+        .spawn()
+        .with_context(|| format!("failed to spawn {}", binary.display()))?;
+
+    let guard = ServerGuard(Some(child));
+
+    // Poll until the server is ready.
+    let mut delay = Duration::from_millis(100);
+    let max_wait = Duration::from_secs(3);
+    let start = std::time::Instant::now();
+
+    loop {
+        tokio::time::sleep(delay).await;
+
+        if probe_server(server_addr).await {
+            eprintln!("server ready");
+            return Ok(guard);
+        }
+
+        if start.elapsed() > max_wait {
+            anyhow::bail!(
+                "auto-started qpq-server but it did not become ready within {max_wait:?}"
+            );
+        }
+
+        delay = (delay * 2).min(Duration::from_secs(1));
+    }
+}
+
+// ── Helpers ──────────────────────────────────────────────────────────────────
+
+/// Build a `ClientConfig` from CLI args.
+fn build_config(args: &Args) -> anyhow::Result<ClientConfig> {
+    let server_addr = args
+        .server
+        .parse()
+        .with_context(|| format!("invalid server address: {}", args.server))?;
+
+    Ok(ClientConfig {
+        server_addr,
+        server_name: args.server_name.clone(),
+        db_path: args.db_path.clone(),
+        db_password: args.db_password.clone(),
+        state_path: args.state.clone(),
+        accept_invalid_certs: args.danger_accept_invalid_certs,
+        ..ClientConfig::default()
+    })
+}
+
+/// Build, connect, and return a `QpqClient`. Loads identity from state file
+/// if it exists.
+async fn connect_client(args: &Args) -> anyhow::Result<QpqClient> {
+    let config = build_config(args)?;
+    let mut client = QpqClient::new(config);
+
+    // Try loading identity from state file.
+    if args.state.exists() {
+        match quicproquo_sdk::state::load_state(&args.state, args.db_password.as_deref()) {
+            Ok(stored) => {
+                let keypair = quicproquo_core::IdentityKeypair::from_seed(stored.identity_seed);
+                client.set_identity_key(keypair.public_key_bytes().to_vec());
+            }
+            Err(e) => {
+                tracing::debug!("could not load state from {}: {e}", args.state.display());
+            }
+        }
+    }
+
+    client.connect().await.context("failed to connect to server")?;
+    Ok(client)
+}
+
+// ── Entry point ──────────────────────────────────────────────────────────────
+
+pub fn main() {
+    // Install the rustls crypto provider before any TLS operations.
+    let _ = rustls::crypto::ring::default_provider().install_default();
+
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| tracing_subscriber::EnvFilter::new("warn")),
+        )
+        .init();
+
+    let args = Args::parse();
+
+    let rt = tokio::runtime::Builder::new_multi_thread()
+        .enable_all()
+        .build()
+        .expect("failed to create tokio runtime");
+
+    if let Err(e) = rt.block_on(run(args)) {
+        eprintln!("error: {e:#}");
+        std::process::exit(1);
+    }
+}
+
+async fn run(args: Args) -> anyhow::Result<()> {
+    // Auto-start server if needed (except for whoami which is local-only).
+    let data_dir = args.state.parent().unwrap_or_else(|| Path::new("."));
+    let _server_guard = match args.command {
+        Cmd::Whoami => ServerGuard(None),
+        _ => ensure_server_running(&args.server, data_dir, args.no_server).await?,
+    };
+
+    match args.command {
+        Cmd::RegisterUser {
+            ref username,
+            ref password,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_register_user(&mut client, username, password)
+                .await
+                .context("register-user failed")?;
+        }
+
+        Cmd::Login {
+            ref username,
+            ref password,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_login(&mut client, username, password)
+                .await
+                .context("login failed")?;
+        }
+
+        Cmd::Whoami => {
+            // Whoami is local-only — create client without connecting.
+            let config = build_config(&args)?;
+            let mut client = QpqClient::new(config);
+            if args.state.exists() {
+                match quicproquo_sdk::state::load_state(
+                    &args.state,
+                    args.db_password.as_deref(),
+                ) {
+                    Ok(stored) => {
+                        let keypair =
+                            quicproquo_core::IdentityKeypair::from_seed(stored.identity_seed);
+                        client.set_identity_key(keypair.public_key_bytes().to_vec());
+                    }
+                    Err(e) => {
+                        eprintln!("warning: could not load state: {e}");
+                    }
+                }
+            }
+            v2_commands::cmd_whoami(&client);
+        }
+
+        Cmd::Health => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_health(&mut client)
+                .await
+                .context("health check failed")?;
+        }
+
+        Cmd::Resolve { ref username } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_resolve(&mut client, username)
+                .await
+                .context("resolve failed")?;
+        }
+
+        Cmd::Dm { ref username } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_resolve(&mut client, username)
+                .await
+                .context("dm setup failed")?;
+            // For now, print the resolved key. Full DM creation requires
+            // MLS group state, which will be handled in the REPL flow.
+            println!("(DM creation with full MLS setup is available in the REPL)");
+        }
+
+        Cmd::Send { ref to, ref msg } => {
+            let _ = (to, msg);
+            let _client = connect_client(&args).await?;
+            // Full send requires MLS group state restoration — deferred to REPL.
+            println!("(send is currently available in the REPL; one-shot send coming soon)");
+        }
+
+        Cmd::Recv { ref from } => {
+            let _ = from;
+            let _client = connect_client(&args).await?;
+            println!("(recv is currently available in the REPL; one-shot recv coming soon)");
+        }
+
+        Cmd::Group {
+            action: GroupCmd::Create { ref name },
+        } => {
+            let _ = name;
+            let _client = connect_client(&args).await?;
+            println!("(group create is currently available in the REPL; one-shot coming soon)");
+        }
+
+        Cmd::Group {
+            action:
+                GroupCmd::Invite {
+                    ref group,
+                    ref user,
+                },
+        } => {
+            let _ = (group, user);
+            let _client = connect_client(&args).await?;
+            println!("(group invite is currently available in the REPL; one-shot coming soon)");
+        }
+
+        Cmd::Devices {
+            action: DevicesCmd::List,
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_devices_list(&mut client)
+                .await
+                .context("devices list failed")?;
+        }
+
+        Cmd::Devices {
+            action: DevicesCmd::Register { ref id, ref name },
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_devices_register(&mut client, id, name)
+                .await
+                .context("device register failed")?;
+        }
+
+        Cmd::Devices {
+            action: DevicesCmd::Revoke { ref id },
+        } => {
+            let mut client = connect_client(&args).await?;
+            v2_commands::cmd_devices_revoke(&mut client, id)
+                .await
+                .context("device revoke failed")?;
+        }
+    }
+
+    Ok(())
+}