ferry_core/

lib.rs

pub mod error;

use std::collections::{BTreeMap, BTreeSet};
use std::fs::Metadata;
use std::io::SeekFrom;
use std::net::SocketAddr;
use std::path::{Component, Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, Mutex};
use std::time::{Duration, SystemTime, UNIX_EPOCH};

use directories::BaseDirs;
use mdns_sd::{ResolvedService, ServiceDaemon, ServiceEvent, ServiceInfo};
use quinn::crypto::rustls::QuicClientConfig;
use rcgen::{CertifiedKey, generate_simple_self_signed};
use rustls::client::danger::{HandshakeSignatureValid, ServerCertVerified, ServerCertVerifier};
use rustls::crypto::{CryptoProvider, verify_tls12_signature, verify_tls13_signature};
use rustls::pki_types::{CertificateDer, PrivateKeyDer, PrivatePkcs8KeyDer, ServerName, UnixTime};
use rustls::{DigitallySignedStruct, SignatureScheme};
use serde::{Deserialize, Serialize};
use tokio::io::{AsyncReadExt, AsyncSeekExt, AsyncWriteExt};
use uuid::Uuid;

pub use error::{Error, Result};

pub const NATIVE_PROTOCOL_VERSION: u16 = 1;
pub const MIN_NATIVE_PROTOCOL_VERSION: u16 = 1;
pub const NATIVE_SERVICE_TYPE: &str = "_ferry._udp.local.";

const DIRECT_MAGIC: &[u8; 8] = b"FERRY01\n";
const MAX_FRAME_LEN: usize = 16 * 1024 * 1024;
const IO_BUFFER_SIZE: usize = 64 * 1024;
const MANIFEST_VERSION: u16 = 1;
const DEFAULT_CHUNK_SIZE: u64 = 1024 * 1024;
const DEFAULT_MANIFEST_CONCURRENCY: usize = 8;
const CONFIG_DIR_NAME: &str = "ferry";
const PSK_PROOF_CONTEXT: &[u8] = b"fileferry-direct-psk-v1";

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct DirectPeer {
    address: SocketAddr,
    expected_fingerprint: Option<String>,
}

impl DirectPeer {
    pub fn parse(value: &str) -> Result<Self> {
        Ok(Self {
            address: value.parse()?,
            expected_fingerprint: None,
        })
    }

    pub const fn address(&self) -> SocketAddr {
        self.address
    }

    pub const fn from_address(address: SocketAddr) -> Self {
        Self {
            address,
            expected_fingerprint: None,
        }
    }

    pub fn with_expected_fingerprint(mut self, fingerprint: impl Into<String>) -> Result<Self> {
        self.expected_fingerprint = Some(normalized_fingerprint(fingerprint.into())?);
        Ok(self)
    }

    pub fn expected_fingerprint(&self) -> Option<&str> {
        self.expected_fingerprint.as_deref()
    }
}

#[derive(Clone, PartialEq, Eq, Deserialize)]
pub struct PskSecret(String);

impl PskSecret {
    pub fn new(psk: impl Into<String>) -> Result<Self> {
        validate_psk(psk.into()).map(Self)
    }

    fn expose_secret(&self) -> &str {
        &self.0
    }
}

impl std::fmt::Debug for PskSecret {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        formatter.write_str("PskSecret(<redacted>)")
    }
}

impl Serialize for PskSecret {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: serde::Serializer,
    {
        serializer.serialize_str("<redacted>")
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct SendRequest {
    peer: DirectPeer,
    paths: Vec<PathBuf>,
    #[serde(default, skip_serializing)]
    psk: Option<PskSecret>,
}

impl SendRequest {
    pub fn new(peer: DirectPeer, paths: Vec<PathBuf>) -> Result<Self> {
        if paths.is_empty() {
            return Err(Error::InvalidInput(
                "at least one file path is required".to_string(),
            ));
        }

        Ok(Self {
            peer,
            paths,
            psk: None,
        })
    }

    pub const fn peer(&self) -> &DirectPeer {
        &self.peer
    }

    pub fn paths(&self) -> &[PathBuf] {
        &self.paths
    }

    pub fn with_psk(mut self, psk: impl Into<String>) -> Result<Self> {
        self.psk = Some(PskSecret::new(psk)?);
        Ok(self)
    }

    pub fn psk(&self) -> Option<&str> {
        self.psk.as_ref().map(PskSecret::expose_secret)
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ReceiveRequest {
    listen: SocketAddr,
    #[serde(default, skip_serializing)]
    psk: Option<PskSecret>,
}

impl ReceiveRequest {
    pub fn new(listen: SocketAddr) -> Self {
        Self { listen, psk: None }
    }

    pub const fn listen(&self) -> SocketAddr {
        self.listen
    }

    pub fn with_psk(mut self, psk: impl Into<String>) -> Result<Self> {
        self.psk = Some(PskSecret::new(psk)?);
        Ok(self)
    }

    pub fn psk(&self) -> Option<&str> {
        self.psk.as_ref().map(PskSecret::expose_secret)
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct AppConfig {
    pub alias: String,
    pub listen_port: u16,
    pub quic_port: u16,
    pub download_dir: String,
    pub auto_accept_known: bool,
    pub auto_accept_unknown: bool,
    pub discovery: Vec<String>,
    pub max_concurrent_files: usize,
    pub trust: TrustConfig,
}

impl Default for AppConfig {
    fn default() -> Self {
        Self {
            alias: default_alias(),
            listen_port: 53317,
            quic_port: 53318,
            download_dir: "~/Downloads/ferry".to_string(),
            auto_accept_known: true,
            auto_accept_unknown: false,
            discovery: vec!["native".to_string()],
            max_concurrent_files: 8,
            trust: TrustConfig::default(),
        }
    }
}

impl AppConfig {
    pub fn load_or_default() -> Result<Self> {
        Self::load_or_default_from(config_dir()?.join("config.toml"))
    }

    pub fn load_or_default_from(path: impl AsRef<Path>) -> Result<Self> {
        let path = path.as_ref();
        match std::fs::read_to_string(path) {
            Ok(contents) => {
                toml::from_str(&contents).map_err(|error| Error::ConfigParse(error.to_string()))
            }
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(Self::default()),
            Err(source) => Err(Error::IoPath {
                path: path.to_path_buf(),
                source,
            }),
        }
    }

    pub fn save_default_path(&self) -> Result<()> {
        self.save_to_path(config_dir()?.join("config.toml"))
    }

    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<()> {
        write_toml_file(path.as_ref(), self)
    }

    pub fn to_toml_string(&self) -> Result<String> {
        toml::to_string_pretty(self).map_err(|error| Error::ConfigSerialize(error.to_string()))
    }

    pub fn redacted(&self) -> Self {
        let mut config = self.clone();
        config.trust = config.trust.redacted();
        config
    }

    pub fn to_redacted_toml_string(&self) -> Result<String> {
        self.redacted().to_toml_string()
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct DaemonConfig {
    pub listen: SocketAddr,
    pub destination: PathBuf,
}

impl DaemonConfig {
    pub fn from_app_config(config: &AppConfig) -> Result<Self> {
        Ok(Self {
            listen: SocketAddr::from(([0, 0, 0, 0], config.quic_port)),
            destination: expand_home_path(&config.download_dir)?,
        })
    }

    pub fn load_or_default() -> Result<Self> {
        let app_config = AppConfig::load_or_default()?;
        Self::load_or_default_from(config_dir()?.join("daemon.toml"), &app_config)
    }

    pub fn load_or_default_from(path: impl AsRef<Path>, app_config: &AppConfig) -> Result<Self> {
        let path = path.as_ref();
        match std::fs::read_to_string(path) {
            Ok(contents) => {
                toml::from_str(&contents).map_err(|error| Error::ConfigParse(error.to_string()))
            }
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
                Self::from_app_config(app_config)
            }
            Err(source) => Err(Error::IoPath {
                path: path.to_path_buf(),
                source,
            }),
        }
    }

    pub fn save_default_path(&self) -> Result<()> {
        self.save_to_path(config_dir()?.join("daemon.toml"))
    }

    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<()> {
        write_toml_file(path.as_ref(), self)
    }

    pub fn to_toml_string(&self) -> Result<String> {
        toml::to_string_pretty(self).map_err(|error| Error::ConfigSerialize(error.to_string()))
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct TrustConfig {
    pub require_fingerprint: bool,
    pub psk: String,
}

impl Default for TrustConfig {
    fn default() -> Self {
        Self {
            require_fingerprint: true,
            psk: String::new(),
        }
    }
}

impl TrustConfig {
    pub fn redacted(&self) -> Self {
        let psk = if self.psk.is_empty() {
            String::new()
        } else {
            "<redacted>".to_string()
        };
        Self {
            require_fingerprint: self.require_fingerprint,
            psk,
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct NativeIdentity {
    cert_der: Vec<u8>,
    key_der: Vec<u8>,
    fingerprint: String,
}

impl NativeIdentity {
    pub fn load_or_generate() -> Result<Self> {
        Self::load_or_generate_in(config_dir()?)
    }

    pub fn load_or_generate_in(config_dir: impl AsRef<Path>) -> Result<Self> {
        let config_dir = config_dir.as_ref();
        let cert_path = config_dir.join("identity.cert.der");
        let key_path = config_dir.join("identity.key.der");

        if cert_path.exists() && key_path.exists() {
            let cert_der = std::fs::read(&cert_path).map_err(|source| Error::IoPath {
                path: cert_path,
                source,
            })?;
            let key_der = std::fs::read(&key_path).map_err(|source| Error::IoPath {
                path: key_path,
                source,
            })?;

            return Ok(Self::from_parts(cert_der, key_der));
        }

        std::fs::create_dir_all(config_dir).map_err(|source| Error::IoPath {
            path: config_dir.to_path_buf(),
            source,
        })?;

        let identity = Self::generate()?;
        write_private_file(&cert_path, &identity.cert_der)?;
        write_private_file(&key_path, &identity.key_der)?;
        Ok(identity)
    }

    pub fn generate() -> Result<Self> {
        let CertifiedKey { cert, signing_key } =
            generate_simple_self_signed(vec!["localhost".to_string()])?;
        Ok(Self::from_parts(
            cert.der().to_vec(),
            signing_key.serialize_der(),
        ))
    }

    pub fn fingerprint(&self) -> &str {
        &self.fingerprint
    }

    fn cert_chain(&self) -> Vec<CertificateDer<'static>> {
        vec![CertificateDer::from(self.cert_der.clone())]
    }

    fn private_key(&self) -> PrivateKeyDer<'static> {
        PrivateKeyDer::from(PrivatePkcs8KeyDer::from(self.key_der.clone()))
    }

    fn from_parts(cert_der: Vec<u8>, key_der: Vec<u8>) -> Self {
        let fingerprint = blake3::hash(&cert_der).to_hex().to_string();
        Self {
            cert_der,
            key_der,
            fingerprint,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum TransferDirection {
    Send,
    Receive,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct TransferProgress {
    pub direction: TransferDirection,
    pub file_name: String,
    pub bytes_done: u64,
    pub bytes_total: u64,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "event", rename_all = "snake_case")]
pub enum TransferEvent {
    SessionStarted {
        direction: TransferDirection,
        session_id: Uuid,
        files_total: usize,
        bytes_total: u64,
    },
    FileStarted {
        direction: TransferDirection,
        file_name: String,
        bytes_total: u64,
        resume_offset: u64,
    },
    Progress {
        direction: TransferDirection,
        file_name: String,
        bytes_done: u64,
        bytes_total: u64,
    },
    FileFinished {
        direction: TransferDirection,
        file_name: String,
        bytes: u64,
        blake3: String,
        status: TransferFileStatus,
    },
    SessionFinished {
        direction: TransferDirection,
        files_total: usize,
        bytes_total: u64,
        blake3: String,
    },
    SessionCancelled {
        direction: TransferDirection,
        session_id: Uuid,
    },
}

impl TransferEvent {
    pub fn progress(&self) -> Option<TransferProgress> {
        match self {
            Self::Progress {
                direction,
                file_name,
                bytes_done,
                bytes_total,
            } => Some(TransferProgress {
                direction: *direction,
                file_name: file_name.clone(),
                bytes_done: *bytes_done,
                bytes_total: *bytes_total,
            }),
            _ => None,
        }
    }
}

#[derive(Debug, Clone, Default)]
pub struct TransferControl {
    cancelled: Arc<AtomicBool>,
}

impl TransferControl {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn cancel(&self) {
        self.cancelled.store(true, Ordering::SeqCst);
    }

    pub fn is_cancelled(&self) -> bool {
        self.cancelled.load(Ordering::SeqCst)
    }

    fn check_cancelled(&self) -> Result<()> {
        if self.is_cancelled() {
            Err(Error::TransferCancelled)
        } else {
            Ok(())
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TransferSummary {
    pub path: PathBuf,
    pub file_name: String,
    pub bytes: u64,
    pub blake3: String,
    pub files: Vec<TransferFileSummary>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct TransferFileSummary {
    pub path: PathBuf,
    pub relative_path: PathBuf,
    pub bytes: u64,
    pub blake3: String,
    pub status: TransferFileStatus,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum TransferFileStatus {
    Sent,
    Received,
    Skipped,
    Resumed,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct TransferManifest {
    pub version: u16,
    pub session_id: Uuid,
    pub chunk_size: u64,
    pub entries: Vec<ManifestEntry>,
}

impl TransferManifest {
    pub fn file_entries(&self) -> impl Iterator<Item = &ManifestEntry> {
        self.entries
            .iter()
            .filter(|entry| entry.kind == ManifestEntryKind::File)
    }

    pub fn total_file_bytes(&self) -> u64 {
        self.file_entries().map(|entry| entry.size).sum()
    }

    pub fn digest(&self) -> Result<String> {
        let bytes = serde_json::to_vec(self).map_err(|error| Error::Protocol(error.to_string()))?;
        Ok(blake3::hash(&bytes).to_hex().to_string())
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct ManifestEntry {
    pub relative_path: PathBuf,
    pub kind: ManifestEntryKind,
    pub size: u64,
    pub blake3: Option<String>,
    pub chunks: Vec<String>,
    pub unix_mode: Option<u32>,
    pub modified_unix_ms: Option<i128>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum ManifestEntryKind {
    File,
    Directory,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ResumeDecision {
    Create,
    Skip,
    ResumeFrom(u64),
    Conflict(String),
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PeerObservation {
    pub fingerprint: String,
    pub alias: Option<String>,
    pub hostname: Option<String>,
    pub address: SocketAddr,
    pub transports: BTreeSet<String>,
    pub seen_unix_ms: i128,
}

impl PeerObservation {
    pub fn new(fingerprint: impl Into<String>, address: SocketAddr, seen_unix_ms: i128) -> Self {
        Self {
            fingerprint: fingerprint.into(),
            alias: None,
            hostname: None,
            address,
            transports: BTreeSet::new(),
            seen_unix_ms,
        }
    }

    pub fn with_alias(mut self, alias: impl Into<String>) -> Self {
        self.alias = Some(alias.into());
        self
    }

    pub fn with_hostname(mut self, hostname: impl Into<String>) -> Self {
        self.hostname = Some(hostname.into());
        self
    }

    pub fn with_transport(mut self, transport: impl Into<String>) -> Self {
        self.transports.insert(transport.into());
        self
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct PeerRecord {
    pub fingerprint: String,
    pub aliases: BTreeSet<String>,
    pub hostnames: BTreeSet<String>,
    pub addresses: BTreeSet<SocketAddr>,
    pub transports: BTreeSet<String>,
    pub first_seen_unix_ms: i128,
    pub last_seen_unix_ms: i128,
}

impl PeerRecord {
    fn from_observation(observation: PeerObservation) -> Self {
        let mut aliases = BTreeSet::new();
        if let Some(alias) = observation.alias {
            aliases.insert(alias);
        }

        let mut hostnames = BTreeSet::new();
        if let Some(hostname) = observation.hostname {
            hostnames.insert(hostname);
        }

        let mut addresses = BTreeSet::new();
        addresses.insert(observation.address);

        Self {
            fingerprint: observation.fingerprint,
            aliases,
            hostnames,
            addresses,
            transports: observation.transports,
            first_seen_unix_ms: observation.seen_unix_ms,
            last_seen_unix_ms: observation.seen_unix_ms,
        }
    }

    fn merge(&mut self, observation: PeerObservation) {
        if let Some(alias) = observation.alias {
            self.aliases.insert(alias);
        }
        if let Some(hostname) = observation.hostname {
            self.hostnames.insert(hostname);
        }
        self.addresses.insert(observation.address);
        self.transports.extend(observation.transports);
        self.first_seen_unix_ms = self.first_seen_unix_ms.min(observation.seen_unix_ms);
        self.last_seen_unix_ms = self.last_seen_unix_ms.max(observation.seen_unix_ms);
    }

    pub fn preferred_quic_address(&self) -> Option<SocketAddr> {
        if !self.transports.contains("quic") {
            return None;
        }

        self.addresses.iter().copied().next()
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum TrustState {
    Trusted,
    Blocked,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct KnownPeerEntry {
    pub fingerprint: String,
    #[serde(default)]
    pub aliases: BTreeSet<String>,
    #[serde(default)]
    pub hostnames: BTreeSet<String>,
    #[serde(default)]
    pub addresses: BTreeSet<SocketAddr>,
    #[serde(default)]
    pub transports: BTreeSet<String>,
    pub trust_state: TrustState,
    pub first_seen_unix_ms: Option<i128>,
    pub last_seen_unix_ms: Option<i128>,
}

impl KnownPeerEntry {
    pub fn trusted(fingerprint: impl Into<String>) -> Result<Self> {
        let fingerprint = normalized_fingerprint(fingerprint.into())?;
        Ok(Self {
            fingerprint,
            aliases: BTreeSet::new(),
            hostnames: BTreeSet::new(),
            addresses: BTreeSet::new(),
            transports: BTreeSet::new(),
            trust_state: TrustState::Trusted,
            first_seen_unix_ms: None,
            last_seen_unix_ms: None,
        })
    }

    pub fn from_record(record: &PeerRecord, trust_state: TrustState) -> Result<Self> {
        let fingerprint = normalized_fingerprint(record.fingerprint.clone())?;
        Ok(Self {
            fingerprint,
            aliases: record.aliases.clone(),
            hostnames: record.hostnames.clone(),
            addresses: record.addresses.clone(),
            transports: record.transports.clone(),
            trust_state,
            first_seen_unix_ms: Some(record.first_seen_unix_ms),
            last_seen_unix_ms: Some(record.last_seen_unix_ms),
        })
    }
}

#[derive(Debug, Default, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct TrustStore {
    #[serde(default)]
    pub peers: BTreeMap<String, KnownPeerEntry>,
}

impl TrustStore {
    pub fn load_or_default() -> Result<Self> {
        Self::load_or_default_from(config_dir()?.join("known_peers.toml"))
    }

    pub fn load_or_default_from(path: impl AsRef<Path>) -> Result<Self> {
        let path = path.as_ref();
        match std::fs::read_to_string(path) {
            Ok(contents) => {
                toml::from_str(&contents).map_err(|error| Error::ConfigParse(error.to_string()))
            }
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(Self::default()),
            Err(source) => Err(Error::IoPath {
                path: path.to_path_buf(),
                source,
            }),
        }
    }

    pub fn save_default_path(&self) -> Result<()> {
        self.save_to_path(config_dir()?.join("known_peers.toml"))
    }

    pub fn save_to_path(&self, path: impl AsRef<Path>) -> Result<()> {
        write_toml_file(path.as_ref(), self)
    }

    pub fn trust_fingerprint(&mut self, fingerprint: impl Into<String>) -> Result<&KnownPeerEntry> {
        let entry = KnownPeerEntry::trusted(fingerprint)?;
        let fingerprint = entry.fingerprint.clone();
        self.peers
            .entry(fingerprint.clone())
            .and_modify(|existing| existing.trust_state = TrustState::Trusted)
            .or_insert(entry);
        Ok(self
            .peers
            .get(&fingerprint)
            .expect("trusted peer entry should exist"))
    }

    pub fn trust_record(&mut self, record: &PeerRecord) -> Result<&KnownPeerEntry> {
        let entry = KnownPeerEntry::from_record(record, TrustState::Trusted)?;
        let fingerprint = entry.fingerprint.clone();
        self.peers
            .entry(fingerprint.clone())
            .and_modify(|existing| {
                existing.aliases.extend(record.aliases.clone());
                existing.hostnames.extend(record.hostnames.clone());
                existing.addresses.extend(record.addresses.clone());
                existing.transports.extend(record.transports.clone());
                existing.first_seen_unix_ms = Some(
                    existing
                        .first_seen_unix_ms
                        .unwrap_or(record.first_seen_unix_ms)
                        .min(record.first_seen_unix_ms),
                );
                existing.last_seen_unix_ms = Some(
                    existing
                        .last_seen_unix_ms
                        .unwrap_or(record.last_seen_unix_ms)
                        .max(record.last_seen_unix_ms),
                );
                existing.trust_state = TrustState::Trusted;
            })
            .or_insert(entry);
        Ok(self
            .peers
            .get(&fingerprint)
            .expect("trusted peer entry should exist"))
    }

    pub fn trust_direct_address(
        &mut self,
        fingerprint: impl Into<String>,
        address: SocketAddr,
    ) -> Result<&KnownPeerEntry> {
        let mut entry = KnownPeerEntry::trusted(fingerprint)?;
        let seen = system_time_unix_ms(SystemTime::now()).unwrap_or_default();
        entry.addresses.insert(address);
        entry.transports.insert("quic".to_string());
        entry.first_seen_unix_ms = Some(seen);
        entry.last_seen_unix_ms = Some(seen);

        let fingerprint = entry.fingerprint.clone();
        self.peers
            .entry(fingerprint.clone())
            .and_modify(|existing| {
                existing.addresses.insert(address);
                existing.transports.insert("quic".to_string());
                existing.first_seen_unix_ms =
                    Some(existing.first_seen_unix_ms.unwrap_or(seen).min(seen));
                existing.last_seen_unix_ms =
                    Some(existing.last_seen_unix_ms.unwrap_or(seen).max(seen));
                existing.trust_state = TrustState::Trusted;
            })
            .or_insert(entry);
        Ok(self
            .peers
            .get(&fingerprint)
            .expect("trusted peer entry should exist"))
    }

    pub fn is_trusted_fingerprint(&self, fingerprint: &str) -> bool {
        self.peers
            .get(fingerprint)
            .is_some_and(|entry| entry.trust_state == TrustState::Trusted)
    }

    pub fn trusted_fingerprint_for_address(&self, address: SocketAddr) -> Option<&str> {
        self.peers
            .values()
            .find(|entry| {
                entry.trust_state == TrustState::Trusted && entry.addresses.contains(&address)
            })
            .map(|entry| entry.fingerprint.as_str())
    }

    pub fn forget(&mut self, fingerprint: &str) -> bool {
        self.peers.remove(fingerprint).is_some()
    }

    pub fn records(&self) -> impl Iterator<Item = &KnownPeerEntry> {
        self.peers.values()
    }

    pub fn to_toml_string(&self) -> Result<String> {
        toml::to_string_pretty(self).map_err(|error| Error::ConfigSerialize(error.to_string()))
    }
}

#[derive(Debug, Default, Clone, PartialEq, Eq)]
pub struct PeerRegistry {
    peers: BTreeMap<String, PeerRecord>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum PeerLookup<'a> {
    Found(&'a PeerRecord),
    Ambiguous(Vec<&'a PeerRecord>),
    Missing,
}

impl PeerRegistry {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn observe(&mut self, observation: PeerObservation) -> Result<&PeerRecord> {
        if observation.fingerprint.trim().is_empty() {
            return Err(Error::InvalidInput(
                "peer fingerprint must not be empty".to_string(),
            ));
        }

        let fingerprint = observation.fingerprint.clone();
        if let Some(record) = self.peers.get_mut(&fingerprint) {
            record.merge(observation);
        } else {
            self.peers.insert(
                fingerprint.clone(),
                PeerRecord::from_observation(observation),
            );
        }

        Ok(self
            .peers
            .get(&fingerprint)
            .expect("observed peer record should exist"))
    }

    pub fn get_by_fingerprint(&self, fingerprint: &str) -> Option<&PeerRecord> {
        self.peers.get(fingerprint)
    }

    pub fn lookup(&self, query: &str) -> Option<&PeerRecord> {
        match self.lookup_detail(query) {
            PeerLookup::Found(record) => Some(record),
            PeerLookup::Ambiguous(_) | PeerLookup::Missing => None,
        }
    }

    pub fn lookup_detail(&self, query: &str) -> PeerLookup<'_> {
        if let Some(record) = self.peers.get(query) {
            return PeerLookup::Found(record);
        }

        let matches = self
            .peers
            .values()
            .filter(|record| {
                record.fingerprint.starts_with(query)
                    || record.aliases.iter().any(|alias| alias == query)
                    || record.hostnames.iter().any(|hostname| hostname == query)
            })
            .collect::<Vec<_>>();

        match matches.as_slice() {
            [] => PeerLookup::Missing,
            [record] => PeerLookup::Found(record),
            _ => PeerLookup::Ambiguous(matches),
        }
    }

    pub fn records(&self) -> impl Iterator<Item = &PeerRecord> {
        self.peers.values()
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct NativeAnnouncement {
    pub alias: String,
    pub fingerprint: String,
    pub quic_port: u16,
    pub listen_port: Option<u16>,
}

impl NativeAnnouncement {
    pub fn from_config(config: &AppConfig, identity: &NativeIdentity) -> Self {
        Self {
            alias: config.alias.clone(),
            fingerprint: identity.fingerprint().to_string(),
            quic_port: config.quic_port,
            listen_port: Some(config.listen_port),
        }
    }

    fn service_info(&self) -> Result<ServiceInfo> {
        let alias = sanitize_dns_label(&self.alias);
        let fingerprint_prefix = self
            .fingerprint
            .get(..12)
            .unwrap_or(self.fingerprint.as_str());
        let instance = format!("{alias}-{fingerprint_prefix}");
        let hostname = format!("{alias}.local.");
        let properties = [
            ("pv", NATIVE_PROTOCOL_VERSION.to_string()),
            ("minpv", MIN_NATIVE_PROTOCOL_VERSION.to_string()),
            ("fp", self.fingerprint.clone()),
            ("alias", self.alias.clone()),
            ("transports", "quic".to_string()),
            ("quic_port", self.quic_port.to_string()),
            (
                "listen_port",
                self.listen_port
                    .map(|port| port.to_string())
                    .unwrap_or_default(),
            ),
        ];

        ServiceInfo::new(
            NATIVE_SERVICE_TYPE,
            &instance,
            &hostname,
            "",
            self.quic_port,
            &properties[..],
        )
        .map(ServiceInfo::enable_addr_auto)
        .map_err(|error| Error::Discovery(error.to_string()))
    }
}

pub struct NativeAnnouncer {
    daemon: ServiceDaemon,
    fullname: String,
}

impl NativeAnnouncer {
    pub fn start(announcement: &NativeAnnouncement) -> Result<Self> {
        let daemon = ServiceDaemon::new().map_err(|error| Error::Discovery(error.to_string()))?;
        let service = announcement.service_info()?;
        let fullname = service.get_fullname().to_string();
        daemon
            .register(service)
            .map_err(|error| Error::Discovery(error.to_string()))?;
        Ok(Self { daemon, fullname })
    }
}

impl Drop for NativeAnnouncer {
    fn drop(&mut self) {
        let _ = self.daemon.unregister(&self.fullname);
        let _ = self.daemon.shutdown();
    }
}

pub async fn discover_native_peers(timeout: Duration) -> Result<PeerRegistry> {
    let daemon = ServiceDaemon::new().map_err(|error| Error::Discovery(error.to_string()))?;
    let receiver = daemon
        .browse(NATIVE_SERVICE_TYPE)
        .map_err(|error| Error::Discovery(error.to_string()))?;
    let deadline = tokio::time::Instant::now() + timeout;
    let mut registry = PeerRegistry::new();

    loop {
        let now = tokio::time::Instant::now();
        if now >= deadline {
            break;
        }

        let wait = deadline - now;
        match tokio::time::timeout(wait, receiver.recv_async()).await {
            Ok(Ok(ServiceEvent::ServiceResolved(service))) => {
                observe_resolved_service(&mut registry, &service)?;
            }
            Ok(Ok(_)) => {}
            Ok(Err(error)) => {
                return Err(Error::Discovery(error.to_string()));
            }
            Err(_) => break,
        }
    }

    daemon
        .stop_browse(NATIVE_SERVICE_TYPE)
        .map_err(|error| Error::Discovery(error.to_string()))?;
    let _ = daemon.shutdown();
    Ok(registry)
}

fn observe_resolved_service(registry: &mut PeerRegistry, service: &ResolvedService) -> Result<()> {
    let Some(fingerprint) = service.get_property_val_str("fp") else {
        return Ok(());
    };
    let fingerprint = match normalized_fingerprint(fingerprint.to_string()) {
        Ok(fingerprint) => fingerprint,
        Err(_) => return Ok(()),
    };
    let Some(highest_version) = parse_txt_u16(service, "pv") else {
        return Ok(());
    };
    let Some(minimum_version) = parse_txt_u16(service, "minpv") else {
        return Ok(());
    };
    if minimum_version > highest_version
        || minimum_version > NATIVE_PROTOCOL_VERSION
        || highest_version < MIN_NATIVE_PROTOCOL_VERSION
    {
        return Ok(());
    }

    let Some(quic_port) = parse_txt_u16(service, "quic_port") else {
        return Ok(());
    };
    let transports = service
        .get_property_val_str("transports")
        .unwrap_or_default()
        .split(',')
        .map(str::trim)
        .filter(|value| !value.is_empty())
        .map(ToOwned::to_owned)
        .collect::<Vec<_>>();
    if !transports.iter().any(|transport| transport == "quic") {
        return Ok(());
    }

    let alias = service.get_property_val_str("alias").map(ToOwned::to_owned);
    let hostname = Some(service.get_hostname().trim_end_matches('.').to_string());
    let seen_unix_ms = system_time_unix_ms(SystemTime::now()).unwrap_or_default();

    for address in service.get_addresses_v4() {
        let mut observation = PeerObservation::new(
            fingerprint.clone(),
            SocketAddr::from((address, quic_port)),
            seen_unix_ms,
        );
        if let Some(alias) = &alias {
            observation = observation.with_alias(alias.clone());
        }
        if let Some(hostname) = &hostname {
            observation = observation.with_hostname(hostname.clone());
        }
        for transport in &transports {
            observation = observation.with_transport(transport.clone());
        }
        registry.observe(observation)?;
    }

    Ok(())
}

fn parse_txt_u16(service: &ResolvedService, key: &str) -> Option<u16> {
    service.get_property_val_str(key)?.parse().ok()
}

fn sanitize_dns_label(value: &str) -> String {
    let mut label = value
        .chars()
        .map(|ch| {
            if ch.is_ascii_alphanumeric() || ch == '-' {
                ch.to_ascii_lowercase()
            } else {
                '-'
            }
        })
        .collect::<String>();
    while label.contains("--") {
        label = label.replace("--", "-");
    }
    let label = label.trim_matches('-').to_string();
    if label.is_empty() {
        "fileferry-device".to_string()
    } else {
        label
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectReceivePlan {
    files: Vec<DirectFilePlan>,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectProtocolHello {
    protocol_version: u16,
    min_protocol_version: u16,
    client_fingerprint: String,
    #[serde(default)]
    psk: bool,
}

impl DirectProtocolHello {
    fn new(identity: &NativeIdentity, psk: Option<&str>) -> Self {
        Self {
            protocol_version: NATIVE_PROTOCOL_VERSION,
            min_protocol_version: MIN_NATIVE_PROTOCOL_VERSION,
            client_fingerprint: identity.fingerprint().to_string(),
            psk: psk.is_some(),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectProtocolResponse {
    accepted: bool,
    protocol_version: Option<u16>,
    #[serde(default)]
    psk_challenge: Option<String>,
    error: Option<String>,
}

impl DirectProtocolResponse {
    fn accept(protocol_version: u16) -> Self {
        Self {
            accepted: true,
            protocol_version: Some(protocol_version),
            psk_challenge: None,
            error: None,
        }
    }

    fn accept_with_psk(protocol_version: u16, challenge: impl Into<String>) -> Self {
        Self {
            accepted: true,
            protocol_version: Some(protocol_version),
            psk_challenge: Some(challenge.into()),
            error: None,
        }
    }

    fn reject(error: impl Into<String>) -> Self {
        Self {
            accepted: false,
            protocol_version: None,
            psk_challenge: None,
            error: Some(error.into()),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectPskProof {
    proof: String,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectPskResult {
    accepted: bool,
    error: Option<String>,
}

impl DirectPskResult {
    fn accept() -> Self {
        Self {
            accepted: true,
            error: None,
        }
    }

    fn reject(error: impl Into<String>) -> Self {
        Self {
            accepted: false,
            error: Some(error.into()),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectFilePlan {
    relative_path: PathBuf,
    action: DirectFileAction,
    offset: u64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
enum DirectFileAction {
    Receive,
    Skip,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectPayloadHeader {
    relative_path: PathBuf,
    offset: u64,
    bytes: u64,
}

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
struct DirectAck {
    ok: bool,
    error: Option<String>,
}

pub fn validate_send_paths(paths: &[PathBuf]) -> Result<()> {
    if paths.is_empty() {
        return Err(Error::InvalidInput(
            "at least one file path is required".to_string(),
        ));
    }

    for path in paths {
        if path.as_os_str().is_empty() {
            return Err(Error::InvalidInput("empty file path".to_string()));
        }
    }

    Ok(())
}

pub fn display_path(path: &Path) -> String {
    path.to_string_lossy().into_owned()
}

pub async fn build_manifest(paths: &[PathBuf]) -> Result<TransferManifest> {
    validate_send_paths(paths)?;

    let sources = collect_manifest_sources(paths)?;
    let mut seen = BTreeSet::new();
    for source in &sources {
        if !seen.insert(source.relative_path.clone()) {
            return Err(Error::InvalidInput(format!(
                "duplicate transfer path: {}",
                display_path(&source.relative_path)
            )));
        }
    }

    Ok(TransferManifest {
        version: MANIFEST_VERSION,
        session_id: Uuid::new_v4(),
        chunk_size: DEFAULT_CHUNK_SIZE,
        entries: build_manifest_entries(sources).await?,
    })
}

async fn build_manifest_entries(sources: Vec<ManifestSource>) -> Result<Vec<ManifestEntry>> {
    if sources.len() <= 1 {
        let mut entries = Vec::with_capacity(sources.len());
        for source in sources {
            entries.push(build_manifest_entry(source).await?);
        }
        return Ok(entries);
    }

    let len = sources.len();
    let concurrency = std::thread::available_parallelism()
        .map(|parallelism| parallelism.get())
        .unwrap_or(1)
        .clamp(1, DEFAULT_MANIFEST_CONCURRENCY)
        .min(len);
    let mut sources = sources.into_iter().enumerate();
    let mut tasks = tokio::task::JoinSet::new();
    let mut entries = vec![None; len];

    for _ in 0..concurrency {
        if let Some((index, source)) = sources.next() {
            tasks.spawn(async move {
                build_manifest_entry(source)
                    .await
                    .map(|entry| (index, entry))
            });
        }
    }

    while let Some(result) = tasks.join_next().await {
        let (index, entry) =
            result.map_err(|error| Error::Protocol(format!("manifest task failed: {error}")))??;
        entries[index] = Some(entry);

        if let Some((index, source)) = sources.next() {
            tasks.spawn(async move {
                build_manifest_entry(source)
                    .await
                    .map(|entry| (index, entry))
            });
        }
    }

    Ok(entries
        .into_iter()
        .map(|entry| entry.expect("manifest task should fill every entry"))
        .collect())
}

pub fn safe_destination_path(destination: &Path, relative_path: &Path) -> Result<PathBuf> {
    validate_relative_transfer_path(relative_path)?;
    Ok(destination.join(relative_path))
}

pub async fn decide_resume(
    destination: &Path,
    entry: &ManifestEntry,
    chunk_size: u64,
) -> Result<ResumeDecision> {
    if entry.kind != ManifestEntryKind::File {
        return Ok(ResumeDecision::Create);
    }

    let path = safe_destination_path(destination, &entry.relative_path)?;
    let metadata = match tokio::fs::metadata(&path).await {
        Ok(metadata) => metadata,
        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
            return Ok(ResumeDecision::Create);
        }
        Err(source) => {
            return Err(Error::IoPath { path, source });
        }
    };

    if !metadata.is_file() {
        return Ok(ResumeDecision::Conflict(format!(
            "{} already exists and is not a regular file",
            display_path(&path)
        )));
    }

    if metadata.len() == entry.size {
        let expected = entry
            .blake3
            .as_deref()
            .ok_or_else(|| Error::Protocol("file manifest entry is missing BLAKE3".to_string()))?;
        let actual = hash_file(&path).await?;
        return if actual == expected {
            Ok(ResumeDecision::Skip)
        } else {
            Ok(ResumeDecision::Conflict(format!(
                "{} already exists with different contents",
                display_path(&path)
            )))
        };
    }

    if metadata.len() > entry.size {
        return Ok(ResumeDecision::Conflict(format!(
            "{} is larger than incoming file",
            display_path(&path)
        )));
    }

    let verified_offset = verified_prefix_offset(&path, entry, metadata.len(), chunk_size).await?;
    if verified_offset > 0 {
        Ok(ResumeDecision::ResumeFrom(verified_offset))
    } else {
        Ok(ResumeDecision::Conflict(format!(
            "{} already exists and does not match a verified prefix",
            display_path(&path)
        )))
    }
}

pub async fn send_direct_file(
    request: &SendRequest,
    identity: &NativeIdentity,
    mut events: impl FnMut(TransferEvent),
) -> Result<TransferSummary> {
    send_direct_file_with_control(request, identity, TransferControl::new(), &mut events).await
}

pub async fn send_direct_file_with_control(
    request: &SendRequest,
    identity: &NativeIdentity,
    control: TransferControl,
    mut events: impl FnMut(TransferEvent),
) -> Result<TransferSummary> {
    send_direct_file_with_control_and_trust(request, identity, control, &mut events, |_| Ok(()))
        .await
}

pub async fn send_direct_file_with_control_and_trust(
    request: &SendRequest,
    identity: &NativeIdentity,
    control: TransferControl,
    mut events: impl FnMut(TransferEvent),
    mut confirm_unpinned_receiver: impl FnMut(&str) -> Result<()>,
) -> Result<TransferSummary> {
    ensure_rustls_provider();

    control.check_cancelled()?;
    let manifest = build_manifest(request.paths()).await?;
    let sources = manifest_source_map(request.paths())?;
    events(TransferEvent::SessionStarted {
        direction: TransferDirection::Send,
        session_id: manifest.session_id,
        files_total: manifest.file_entries().count(),
        bytes_total: manifest.total_file_bytes(),
    });
    control.check_cancelled()?;

    let (client_config, server_fingerprint) = client_config_capturing_server_fingerprint()?;
    let mut endpoint = quinn::Endpoint::client(SocketAddr::from(([0, 0, 0, 0], 0)))?;
    endpoint.set_default_client_config(client_config);
    let connection = endpoint
        .connect(request.peer().address(), "localhost")?
        .await?;
    let actual = captured_server_fingerprint(&server_fingerprint)?;
    match request.peer().expected_fingerprint() {
        Some(expected) if actual != expected => {
            connection.close(1u32.into(), b"fingerprint mismatch");
            return Err(Error::PeerFingerprintMismatch {
                expected: expected.to_string(),
                actual,
            });
        }
        Some(_) => {}
        None => {
            if let Err(error) = confirm_unpinned_receiver(&actual) {
                connection.close(1u32.into(), b"receiver fingerprint not trusted");
                return Err(error);
            }
        }
    }
    let (mut send, mut recv) = connection.open_bi().await?;

    send.write_all(DIRECT_MAGIC).await?;
    write_json_frame(
        &mut send,
        &DirectProtocolHello::new(identity, request.psk()),
    )
    .await?;
    let protocol: DirectProtocolResponse = read_json_frame(&mut recv).await?;
    if !protocol.accepted {
        return Err(Error::Protocol(protocol.error.unwrap_or_else(|| {
            "receiver rejected protocol negotiation".to_string()
        })));
    }
    if protocol.protocol_version != Some(NATIVE_PROTOCOL_VERSION) {
        return Err(Error::Protocol(format!(
            "receiver selected unsupported protocol version {:?}",
            protocol.protocol_version
        )));
    }
    match (request.psk(), protocol.psk_challenge.as_deref()) {
        (Some(psk), Some(challenge)) => {
            let proof = DirectPskProof {
                proof: psk_proof(
                    psk,
                    challenge,
                    identity.fingerprint(),
                    NATIVE_PROTOCOL_VERSION,
                )?,
            };
            write_json_frame(&mut send, &proof).await?;
            let auth: DirectPskResult = read_json_frame(&mut recv).await?;
            if !auth.accepted {
                return Err(Error::Authentication(
                    auth.error
                        .unwrap_or_else(|| "PSK authentication rejected".to_string()),
                ));
            }
        }
        (Some(_), None) => {
            return Err(Error::Authentication(
                "receiver is not configured for PSK mode".to_string(),
            ));
        }
        (None, Some(_)) => {
            return Err(Error::Authentication(
                "receiver requires PSK authentication".to_string(),
            ));
        }
        (None, None) => {}
    }

    write_json_frame(&mut send, &manifest).await?;

    let plan: DirectReceivePlan = read_json_frame(&mut recv).await?;
    let mut summaries = Vec::new();
    for file_plan in plan.files {
        let Some(entry) = manifest
            .file_entries()
            .find(|entry| entry.relative_path == file_plan.relative_path)
        else {
            return Err(Error::Protocol(format!(
                "receiver requested unknown file: {}",
                display_path(&file_plan.relative_path)
            )));
        };

        let Some(source_path) = sources.get(&file_plan.relative_path) else {
            return Err(Error::Protocol(format!(
                "missing source for manifest file: {}",
                display_path(&file_plan.relative_path)
            )));
        };

        if file_plan.action == DirectFileAction::Skip {
            let blake3 = entry.blake3.clone().unwrap_or_default();
            events(TransferEvent::FileFinished {
                direction: TransferDirection::Send,
                file_name: display_path(&entry.relative_path),
                bytes: entry.size,
                blake3: blake3.clone(),
                status: TransferFileStatus::Skipped,
            });
            summaries.push(TransferFileSummary {
                path: source_path.clone(),
                relative_path: entry.relative_path.clone(),
                bytes: entry.size,
                blake3,
                status: TransferFileStatus::Skipped,
            });
            continue;
        }

        match send_payload_file(
            &mut send,
            source_path,
            entry,
            file_plan.offset,
            &control,
            &mut events,
        )
        .await
        {
            Ok(()) => {}
            Err(Error::TransferCancelled) => {
                events(TransferEvent::SessionCancelled {
                    direction: TransferDirection::Send,
                    session_id: manifest.session_id,
                });
                connection.close(1u32.into(), b"cancelled");
                return Err(Error::TransferCancelled);
            }
            Err(error) => return Err(error),
        }
        let status = if file_plan.offset > 0 {
            TransferFileStatus::Resumed
        } else {
            TransferFileStatus::Sent
        };
        let blake3 = entry.blake3.clone().unwrap_or_default();
        events(TransferEvent::FileFinished {
            direction: TransferDirection::Send,
            file_name: display_path(&entry.relative_path),
            bytes: entry.size,
            blake3: blake3.clone(),
            status,
        });
        summaries.push(TransferFileSummary {
            path: source_path.clone(),
            relative_path: entry.relative_path.clone(),
            bytes: entry.size,
            blake3,
            status,
        });
    }
    send.finish()?;

    let ack: DirectAck = read_json_frame(&mut recv).await?;
    if !ack.ok {
        return Err(Error::Transfer(
            ack.error
                .unwrap_or_else(|| "receiver rejected transfer".to_string()),
        ));
    }

    connection.close(0u32.into(), b"done");
    endpoint.wait_idle().await;

    let summary = summary_from_files(&manifest, summaries)?;
    events(TransferEvent::SessionFinished {
        direction: TransferDirection::Send,
        files_total: summary.files.len(),
        bytes_total: summary.bytes,
        blake3: summary.blake3.clone(),
    });
    Ok(summary)
}

pub async fn receive_direct_file(
    request: &ReceiveRequest,
    destination: impl AsRef<Path>,
    identity: &NativeIdentity,
    events: impl FnMut(TransferEvent),
) -> Result<TransferSummary> {
    receive_direct_file_with_control(
        request,
        destination,
        identity,
        TransferControl::new(),
        events,
    )
    .await
}

pub async fn receive_direct_file_with_control(
    request: &ReceiveRequest,
    destination: impl AsRef<Path>,
    identity: &NativeIdentity,
    control: TransferControl,
    mut events: impl FnMut(TransferEvent),
) -> Result<TransferSummary> {
    ensure_rustls_provider();

    control.check_cancelled()?;
    let destination = destination.as_ref();
    tokio::fs::create_dir_all(destination)
        .await
        .map_err(|source| Error::IoPath {
            path: destination.to_path_buf(),
            source,
        })?;

    let server_config =
        quinn::ServerConfig::with_single_cert(identity.cert_chain(), identity.private_key())?;
    let endpoint = quinn::Endpoint::server(server_config, request.listen())?;
    let incoming = endpoint.accept().await.ok_or(Error::NoIncomingConnection)?;
    let connection = incoming.await?;
    let (mut send, mut recv) = connection.accept_bi().await?;

    let result = receive_stream_file(
        destination,
        request.psk(),
        &mut recv,
        &mut send,
        &control,
        &mut events,
    )
    .await;
    let ack = match &result {
        Ok(_) => DirectAck {
            ok: true,
            error: None,
        },
        Err(error) => DirectAck {
            ok: false,
            error: Some(error.to_string()),
        },
    };
    write_json_frame(&mut send, &ack).await?;
    send.finish()?;
    let _ = tokio::time::timeout(Duration::from_secs(1), connection.closed()).await;
    endpoint.close(0u32.into(), b"done");
    endpoint.wait_idle().await;

    result
}

async fn receive_stream_file(
    destination: &Path,
    psk: Option<&str>,
    recv: &mut quinn::RecvStream,
    send: &mut quinn::SendStream,
    control: &TransferControl,
    events: &mut impl FnMut(TransferEvent),
) -> Result<TransferSummary> {
    let mut magic = [0; DIRECT_MAGIC.len()];
    recv.read_exact(&mut magic).await?;
    if &magic != DIRECT_MAGIC {
        return Err(Error::Protocol("bad direct-transfer magic".to_string()));
    }

    let hello: DirectProtocolHello = read_json_frame(recv).await?;
    let protocol = negotiate_direct_protocol(&hello, psk);
    write_json_frame(send, &protocol).await?;
    if !protocol.accepted {
        return Err(Error::Protocol(protocol.error.unwrap_or_else(|| {
            "unsupported direct protocol version".to_string()
        })));
    }
    if let (Some(psk), Some(challenge)) = (psk, protocol.psk_challenge.as_deref()) {
        let proof: DirectPskProof = read_json_frame(recv).await?;
        let expected = psk_proof(
            psk,
            challenge,
            &hello.client_fingerprint,
            protocol.protocol_version.unwrap_or(NATIVE_PROTOCOL_VERSION),
        )?;
        if proof.proof != expected {
            write_json_frame(send, &DirectPskResult::reject("PSK proof mismatch")).await?;
            return Err(Error::Authentication("PSK proof mismatch".to_string()));
        }
        write_json_frame(send, &DirectPskResult::accept()).await?;
    }

    let manifest: TransferManifest = read_json_frame(recv).await?;
    validate_manifest(&manifest)?;
    events(TransferEvent::SessionStarted {
        direction: TransferDirection::Receive,
        session_id: manifest.session_id,
        files_total: manifest.file_entries().count(),
        bytes_total: manifest.total_file_bytes(),
    });
    control.check_cancelled()?;

    for entry in &manifest.entries {
        if entry.kind == ManifestEntryKind::Directory {
            let path = safe_destination_path(destination, &entry.relative_path)?;
            tokio::fs::create_dir_all(&path)
                .await
                .map_err(|source| Error::IoPath { path, source })?;
        }
    }

    let mut plan = DirectReceivePlan { files: Vec::new() };
    for entry in manifest.file_entries() {
        let decision = decide_resume(destination, entry, manifest.chunk_size).await?;
        let (action, offset) = match decision {
            ResumeDecision::Create => (DirectFileAction::Receive, 0),
            ResumeDecision::Skip => (DirectFileAction::Skip, entry.size),
            ResumeDecision::ResumeFrom(offset) => (DirectFileAction::Receive, offset),
            ResumeDecision::Conflict(message) => return Err(Error::InvalidInput(message)),
        };
        plan.files.push(DirectFilePlan {
            relative_path: entry.relative_path.clone(),
            action,
            offset,
        });
    }
    write_json_frame(send, &plan).await?;

    let mut summaries = Vec::new();
    for file_plan in &plan.files {
        let Some(entry) = manifest
            .file_entries()
            .find(|entry| entry.relative_path == file_plan.relative_path)
        else {
            return Err(Error::Protocol(format!(
                "planned file missing from manifest: {}",
                display_path(&file_plan.relative_path)
            )));
        };

        let final_path = safe_destination_path(destination, &entry.relative_path)?;
        if file_plan.action == DirectFileAction::Skip {
            let blake3 = entry.blake3.clone().unwrap_or_default();
            events(TransferEvent::FileFinished {
                direction: TransferDirection::Receive,
                file_name: display_path(&entry.relative_path),
                bytes: entry.size,
                blake3: blake3.clone(),
                status: TransferFileStatus::Skipped,
            });
            summaries.push(TransferFileSummary {
                path: final_path,
                relative_path: entry.relative_path.clone(),
                bytes: entry.size,
                blake3,
                status: TransferFileStatus::Skipped,
            });
            continue;
        }

        match receive_payload_file(recv, destination, entry, file_plan.offset, control, events)
            .await
        {
            Ok(()) => {}
            Err(Error::TransferCancelled) => {
                events(TransferEvent::SessionCancelled {
                    direction: TransferDirection::Receive,
                    session_id: manifest.session_id,
                });
                return Err(Error::TransferCancelled);
            }
            Err(error) => return Err(error),
        }
        let actual_hash = hash_file(&final_path).await?;
        let expected_hash = entry
            .blake3
            .as_deref()
            .ok_or_else(|| Error::Protocol("file manifest entry is missing BLAKE3".to_string()))?;
        if actual_hash != expected_hash {
            return Err(Error::Transfer(format!(
                "BLAKE3 hash mismatch for {}",
                display_path(&entry.relative_path)
            )));
        }

        let status = if file_plan.offset > 0 {
            TransferFileStatus::Resumed
        } else {
            TransferFileStatus::Received
        };
        events(TransferEvent::FileFinished {
            direction: TransferDirection::Receive,
            file_name: display_path(&entry.relative_path),
            bytes: entry.size,
            blake3: actual_hash.clone(),
            status,
        });
        summaries.push(TransferFileSummary {
            path: final_path,
            relative_path: entry.relative_path.clone(),
            bytes: entry.size,
            blake3: actual_hash,
            status,
        });
    }

    let summary = summary_from_files(&manifest, summaries)?;
    events(TransferEvent::SessionFinished {
        direction: TransferDirection::Receive,
        files_total: summary.files.len(),
        bytes_total: summary.bytes,
        blake3: summary.blake3.clone(),
    });
    Ok(summary)
}

async fn send_payload_file(
    send: &mut quinn::SendStream,
    source_path: &Path,
    entry: &ManifestEntry,
    offset: u64,
    control: &TransferControl,
    events: &mut impl FnMut(TransferEvent),
) -> Result<()> {
    if offset > entry.size {
        return Err(Error::Protocol(format!(
            "resume offset exceeds file size for {}",
            display_path(&entry.relative_path)
        )));
    }

    let header = DirectPayloadHeader {
        relative_path: entry.relative_path.clone(),
        offset,
        bytes: entry.size - offset,
    };
    write_json_frame(send, &header).await?;
    events(TransferEvent::FileStarted {
        direction: TransferDirection::Send,
        file_name: display_path(&entry.relative_path),
        bytes_total: entry.size,
        resume_offset: offset,
    });

    let mut file = tokio::fs::File::open(source_path)
        .await
        .map_err(|source| Error::IoPath {
            path: source_path.to_path_buf(),
            source,
        })?;
    file.seek(SeekFrom::Start(offset))
        .await
        .map_err(|source| Error::IoPath {
            path: source_path.to_path_buf(),
            source,
        })?;

    let mut buffer = vec![0; IO_BUFFER_SIZE];
    let mut bytes_done = offset;
    while bytes_done < entry.size {
        control.check_cancelled()?;
        let remaining = entry.size - bytes_done;
        let read_size = buffer.len().min(remaining as usize);
        let read = file
            .read(&mut buffer[..read_size])
            .await
            .map_err(|source| Error::IoPath {
                path: source_path.to_path_buf(),
                source,
            })?;
        if read == 0 {
            return Err(Error::Protocol(format!(
                "source file ended early: {}",
                display_path(source_path)
            )));
        }
        send.write_all(&buffer[..read]).await?;
        bytes_done += read as u64;
        events(TransferEvent::Progress {
            direction: TransferDirection::Send,
            file_name: display_path(&entry.relative_path),
            bytes_done,
            bytes_total: entry.size,
        });
        control.check_cancelled()?;
    }

    Ok(())
}

async fn receive_payload_file(
    recv: &mut quinn::RecvStream,
    destination: &Path,
    entry: &ManifestEntry,
    offset: u64,
    control: &TransferControl,
    events: &mut impl FnMut(TransferEvent),
) -> Result<()> {
    let header: DirectPayloadHeader = read_json_frame(recv).await?;
    if header.relative_path != entry.relative_path
        || header.offset != offset
        || header.bytes != entry.size - offset
    {
        return Err(Error::Protocol(format!(
            "payload header does not match receive plan for {}",
            display_path(&entry.relative_path)
        )));
    }
    events(TransferEvent::FileStarted {
        direction: TransferDirection::Receive,
        file_name: display_path(&entry.relative_path),
        bytes_total: entry.size,
        resume_offset: offset,
    });

    let final_path = safe_destination_path(destination, &entry.relative_path)?;
    if let Some(parent) = final_path.parent() {
        tokio::fs::create_dir_all(parent)
            .await
            .map_err(|source| Error::IoPath {
                path: parent.to_path_buf(),
                source,
            })?;
    }

    let write_path = if offset == 0 {
        temp_path_for(&final_path)
    } else {
        final_path.clone()
    };

    let mut file = if offset == 0 {
        tokio::fs::File::create(&write_path)
            .await
            .map_err(|source| Error::IoPath {
                path: write_path.clone(),
                source,
            })?
    } else {
        let mut file = tokio::fs::OpenOptions::new()
            .write(true)
            .open(&write_path)
            .await
            .map_err(|source| Error::IoPath {
                path: write_path.clone(),
                source,
            })?;
        file.set_len(offset).await.map_err(|source| Error::IoPath {
            path: write_path.clone(),
            source,
        })?;
        file.seek(SeekFrom::Start(offset))
            .await
            .map_err(|source| Error::IoPath {
                path: write_path.clone(),
                source,
            })?;
        file
    };

    let mut bytes_done = offset;
    let mut bytes_remaining = header.bytes;
    let mut buffer = vec![0; IO_BUFFER_SIZE];
    while bytes_remaining > 0 {
        if control.is_cancelled() {
            if offset == 0 {
                let _ = tokio::fs::remove_file(&write_path).await;
            }
            return Err(Error::TransferCancelled);
        }
        let read_size = buffer.len().min(bytes_remaining as usize);
        let read = match recv.read(&mut buffer[..read_size]).await {
            Ok(Some(read)) => read,
            Ok(None) => {
                if offset == 0 {
                    let _ = tokio::fs::remove_file(&write_path).await;
                }
                return Err(Error::Protocol(
                    "stream ended before file payload".to_string(),
                ));
            }
            Err(error) => {
                if offset == 0 {
                    let _ = tokio::fs::remove_file(&write_path).await;
                }
                return Err(Error::Read(error));
            }
        };

        file.write_all(&buffer[..read])
            .await
            .map_err(|source| Error::IoPath {
                path: write_path.clone(),
                source,
            })?;
        bytes_done += read as u64;
        bytes_remaining -= read as u64;
        events(TransferEvent::Progress {
            direction: TransferDirection::Receive,
            file_name: display_path(&entry.relative_path),
            bytes_done,
            bytes_total: entry.size,
        });
        if control.is_cancelled() {
            if offset == 0 {
                let _ = tokio::fs::remove_file(&write_path).await;
            }
            return Err(Error::TransferCancelled);
        }
    }

    file.flush().await.map_err(|source| Error::IoPath {
        path: write_path.clone(),
        source,
    })?;
    drop(file);

    if offset == 0 {
        tokio::fs::rename(&write_path, &final_path)
            .await
            .map_err(|source| Error::IoPath {
                path: final_path,
                source,
            })?;
    }

    Ok(())
}

async fn write_json_frame<T: Serialize>(send: &mut quinn::SendStream, value: &T) -> Result<()> {
    let bytes = serde_json::to_vec(value).map_err(|error| Error::Protocol(error.to_string()))?;
    if bytes.len() > MAX_FRAME_LEN {
        return Err(Error::Protocol("frame exceeds maximum length".to_string()));
    }
    send.write_all(&(bytes.len() as u32).to_be_bytes()).await?;
    send.write_all(&bytes).await?;
    Ok(())
}

async fn read_json_frame<T: for<'de> Deserialize<'de>>(recv: &mut quinn::RecvStream) -> Result<T> {
    let mut len = [0; 4];
    recv.read_exact(&mut len).await?;
    let len = u32::from_be_bytes(len) as usize;
    if len > MAX_FRAME_LEN {
        return Err(Error::Protocol("frame exceeds maximum length".to_string()));
    }

    let mut bytes = vec![0; len];
    recv.read_exact(&mut bytes).await?;
    serde_json::from_slice(&bytes).map_err(|error| Error::Protocol(error.to_string()))
}

fn negotiate_direct_protocol(
    hello: &DirectProtocolHello,
    psk: Option<&str>,
) -> DirectProtocolResponse {
    if hello.min_protocol_version > NATIVE_PROTOCOL_VERSION {
        return DirectProtocolResponse::reject(format!(
            "peer requires protocol version {}, local max is {}",
            hello.min_protocol_version, NATIVE_PROTOCOL_VERSION
        ));
    }

    if hello.protocol_version < MIN_NATIVE_PROTOCOL_VERSION {
        return DirectProtocolResponse::reject(format!(
            "peer max protocol version {} is below local minimum {}",
            hello.protocol_version, MIN_NATIVE_PROTOCOL_VERSION
        ));
    }

    let selected_version = NATIVE_PROTOCOL_VERSION.min(hello.protocol_version);
    match (psk, hello.psk) {
        (Some(_), false) => DirectProtocolResponse::reject("receiver requires PSK authentication"),
        (Some(_), true) => {
            DirectProtocolResponse::accept_with_psk(selected_version, Uuid::new_v4().to_string())
        }
        (None, true) => DirectProtocolResponse::reject("receiver is not configured for PSK mode"),
        (None, false) => DirectProtocolResponse::accept(selected_version),
    }
}

#[derive(Debug, Clone)]
struct ManifestSource {
    source_path: PathBuf,
    relative_path: PathBuf,
}

fn collect_manifest_sources(paths: &[PathBuf]) -> Result<Vec<ManifestSource>> {
    let mut sources = Vec::new();
    for path in paths {
        let metadata = std::fs::symlink_metadata(path).map_err(|source| Error::IoPath {
            path: path.clone(),
            source,
        })?;
        if metadata.file_type().is_symlink() {
            return Err(Error::InvalidInput(format!(
                "{} is a symlink; symlink transfers are not supported",
                display_path(path)
            )));
        }

        let root_name = path
            .file_name()
            .ok_or_else(|| Error::InvalidInput(format!("{} has no file name", display_path(path))))?
            .to_os_string();
        let relative_path = PathBuf::from(root_name);

        if metadata.is_dir() {
            sources.push(ManifestSource {
                source_path: path.clone(),
                relative_path: relative_path.clone(),
            });
            collect_dir_sources(path, &relative_path, &mut sources)?;
        } else if metadata.is_file() {
            sources.push(ManifestSource {
                source_path: path.clone(),
                relative_path,
            });
        } else {
            return Err(Error::InvalidInput(format!(
                "{} is not a regular file or directory",
                display_path(path)
            )));
        }
    }

    Ok(sources)
}

fn collect_dir_sources(
    dir: &Path,
    relative_dir: &Path,
    sources: &mut Vec<ManifestSource>,
) -> Result<()> {
    let mut entries = std::fs::read_dir(dir)
        .map_err(|source| Error::IoPath {
            path: dir.to_path_buf(),
            source,
        })?
        .collect::<std::result::Result<Vec<_>, _>>()
        .map_err(|source| Error::IoPath {
            path: dir.to_path_buf(),
            source,
        })?;
    entries.sort_by_key(|entry| entry.file_name());

    for entry in entries {
        let path = entry.path();
        let metadata = std::fs::symlink_metadata(&path).map_err(|source| Error::IoPath {
            path: path.clone(),
            source,
        })?;
        if metadata.file_type().is_symlink() {
            return Err(Error::InvalidInput(format!(
                "{} is a symlink; symlink transfers are not supported",
                display_path(&path)
            )));
        }

        let relative_path = relative_dir.join(entry.file_name());
        if metadata.is_dir() {
            sources.push(ManifestSource {
                source_path: path.clone(),
                relative_path: relative_path.clone(),
            });
            collect_dir_sources(&path, &relative_path, sources)?;
        } else if metadata.is_file() {
            sources.push(ManifestSource {
                source_path: path,
                relative_path,
            });
        }
    }

    Ok(())
}

fn manifest_source_map(paths: &[PathBuf]) -> Result<BTreeMap<PathBuf, PathBuf>> {
    Ok(collect_manifest_sources(paths)?
        .into_iter()
        .filter_map(|source| {
            let metadata = std::fs::metadata(&source.source_path).ok()?;
            metadata
                .is_file()
                .then_some((source.relative_path, source.source_path))
        })
        .collect())
}

async fn build_manifest_entry(source: ManifestSource) -> Result<ManifestEntry> {
    validate_relative_transfer_path(&source.relative_path)?;
    let metadata = tokio::fs::metadata(&source.source_path)
        .await
        .map_err(|source_error| Error::IoPath {
            path: source.source_path.clone(),
            source: source_error,
        })?;
    let unix_mode = unix_mode(&metadata);
    let modified_unix_ms = modified_unix_ms(&metadata);

    if metadata.is_dir() {
        return Ok(ManifestEntry {
            relative_path: source.relative_path,
            kind: ManifestEntryKind::Directory,
            size: 0,
            blake3: None,
            chunks: Vec::new(),
            unix_mode,
            modified_unix_ms,
        });
    }

    let (blake3, chunks) = hash_file_with_chunks(&source.source_path, DEFAULT_CHUNK_SIZE).await?;
    Ok(ManifestEntry {
        relative_path: source.relative_path,
        kind: ManifestEntryKind::File,
        size: metadata.len(),
        blake3: Some(blake3),
        chunks,
        unix_mode,
        modified_unix_ms,
    })
}

fn validate_manifest(manifest: &TransferManifest) -> Result<()> {
    if manifest.version != MANIFEST_VERSION {
        return Err(Error::Protocol(format!(
            "unsupported manifest version {}",
            manifest.version
        )));
    }
    if manifest.chunk_size == 0 {
        return Err(Error::Protocol("manifest chunk size is zero".to_string()));
    }

    let mut seen = BTreeSet::new();
    for entry in &manifest.entries {
        validate_relative_transfer_path(&entry.relative_path)?;
        if !seen.insert(entry.relative_path.clone()) {
            return Err(Error::Protocol(format!(
                "duplicate manifest path: {}",
                display_path(&entry.relative_path)
            )));
        }
        if entry.kind == ManifestEntryKind::File && entry.blake3.is_none() {
            return Err(Error::Protocol(format!(
                "file manifest entry is missing BLAKE3: {}",
                display_path(&entry.relative_path)
            )));
        }
    }

    Ok(())
}

fn validate_relative_transfer_path(path: &Path) -> Result<()> {
    if path.as_os_str().is_empty() || path.is_absolute() {
        return Err(Error::InvalidInput(format!(
            "unsafe transfer path: {}",
            display_path(path)
        )));
    }

    let mut normal_components = 0usize;
    for component in path.components() {
        match component {
            Component::Normal(value) => {
                let Some(name) = value.to_str() else {
                    return Err(Error::InvalidInput(format!(
                        "transfer path must be UTF-8: {}",
                        display_path(path)
                    )));
                };
                validate_path_component(name, path)?;
                normal_components += 1;
            }
            Component::CurDir
            | Component::ParentDir
            | Component::RootDir
            | Component::Prefix(_) => {
                return Err(Error::InvalidInput(format!(
                    "unsafe transfer path: {}",
                    display_path(path)
                )));
            }
        }
    }

    if normal_components == 0 {
        return Err(Error::InvalidInput(format!(
            "unsafe transfer path: {}",
            display_path(path)
        )));
    }

    Ok(())
}

fn validate_path_component(component: &str, full_path: &Path) -> Result<()> {
    if component.is_empty()
        || component.contains('\\')
        || component.contains('/')
        || component.contains(':')
        || component.ends_with(' ')
        || component.ends_with('.')
        || is_windows_reserved_name(component)
    {
        return Err(Error::InvalidInput(format!(
            "unsafe transfer path: {}",
            display_path(full_path)
        )));
    }

    Ok(())
}

fn is_windows_reserved_name(component: &str) -> bool {
    let stem = component
        .split('.')
        .next()
        .unwrap_or(component)
        .trim_end_matches([' ', '.'])
        .to_ascii_uppercase();
    matches!(
        stem.as_str(),
        "CON"
            | "PRN"
            | "AUX"
            | "NUL"
            | "COM1"
            | "COM2"
            | "COM3"
            | "COM4"
            | "COM5"
            | "COM6"
            | "COM7"
            | "COM8"
            | "COM9"
            | "LPT1"
            | "LPT2"
            | "LPT3"
            | "LPT4"
            | "LPT5"
            | "LPT6"
            | "LPT7"
            | "LPT8"
            | "LPT9"
    )
}

async fn hash_file(path: &Path) -> Result<String> {
    hash_file_with_chunks(path, DEFAULT_CHUNK_SIZE)
        .await
        .map(|(hash, _)| hash)
}

async fn hash_file_with_chunks(path: &Path, chunk_size: u64) -> Result<(String, Vec<String>)> {
    let mut file = tokio::fs::File::open(path)
        .await
        .map_err(|source| Error::IoPath {
            path: path.to_path_buf(),
            source,
        })?;
    let mut hasher = blake3::Hasher::new();
    let mut chunk_hasher = blake3::Hasher::new();
    let mut chunk_bytes = 0u64;
    let mut chunks = Vec::new();
    let mut buffer = vec![0; IO_BUFFER_SIZE];

    loop {
        let read = file
            .read(&mut buffer)
            .await
            .map_err(|source| Error::IoPath {
                path: path.to_path_buf(),
                source,
            })?;
        if read == 0 {
            break;
        }
        hasher.update(&buffer[..read]);

        let mut remaining = &buffer[..read];
        while !remaining.is_empty() {
            let take = remaining.len().min((chunk_size - chunk_bytes) as usize);
            chunk_hasher.update(&remaining[..take]);
            chunk_bytes += take as u64;
            remaining = &remaining[take..];
            if chunk_bytes == chunk_size {
                chunks.push(chunk_hasher.finalize().to_hex().to_string());
                chunk_hasher = blake3::Hasher::new();
                chunk_bytes = 0;
            }
        }
    }

    if chunk_bytes > 0 {
        chunks.push(chunk_hasher.finalize().to_hex().to_string());
    }

    Ok((hasher.finalize().to_hex().to_string(), chunks))
}

async fn verified_prefix_offset(
    path: &Path,
    entry: &ManifestEntry,
    existing_len: u64,
    chunk_size: u64,
) -> Result<u64> {
    if existing_len == 0 || entry.chunks.is_empty() {
        return Ok(0);
    }

    let chunks_to_check = (existing_len / chunk_size).min(entry.chunks.len() as u64) as usize;
    if chunks_to_check == 0 {
        return Ok(0);
    }

    let mut file = tokio::fs::File::open(path)
        .await
        .map_err(|source| Error::IoPath {
            path: path.to_path_buf(),
            source,
        })?;
    let mut buffer = vec![0; IO_BUFFER_SIZE];
    let mut verified_chunks = 0usize;

    for expected in entry.chunks.iter().take(chunks_to_check) {
        let mut remaining = chunk_size;
        let mut hasher = blake3::Hasher::new();
        while remaining > 0 {
            let read_size = buffer.len().min(remaining as usize);
            file.read_exact(&mut buffer[..read_size])
                .await
                .map_err(|source| Error::IoPath {
                    path: path.to_path_buf(),
                    source,
                })?;
            hasher.update(&buffer[..read_size]);
            remaining -= read_size as u64;
        }

        if hasher.finalize().to_hex().as_str() != expected {
            break;
        }
        verified_chunks += 1;
    }

    Ok(verified_chunks as u64 * chunk_size)
}

fn summary_from_files(
    manifest: &TransferManifest,
    files: Vec<TransferFileSummary>,
) -> Result<TransferSummary> {
    let bytes = manifest.total_file_bytes();
    let blake3 = if files.len() == 1 {
        files[0].blake3.clone()
    } else {
        manifest.digest()?
    };
    let file_name = if files.len() == 1 {
        display_path(&files[0].relative_path)
    } else {
        format!("{} files", files.len())
    };
    let path = files
        .first()
        .map(|file| file.path.clone())
        .unwrap_or_default();

    Ok(TransferSummary {
        path,
        file_name,
        bytes,
        blake3,
        files,
    })
}

fn temp_path_for(final_path: &Path) -> PathBuf {
    let file_name = final_path
        .file_name()
        .and_then(|name| name.to_str())
        .unwrap_or("transfer");
    final_path.with_file_name(format!(".{file_name}.{}.ferry-part", Uuid::new_v4()))
}

fn modified_unix_ms(metadata: &Metadata) -> Option<i128> {
    system_time_unix_ms(metadata.modified().ok()?)
}

fn system_time_unix_ms(time: SystemTime) -> Option<i128> {
    match time.duration_since(UNIX_EPOCH) {
        Ok(duration) => Some(duration.as_millis() as i128),
        Err(error) => Some(-(error.duration().as_millis() as i128)),
    }
}

#[cfg(unix)]
fn unix_mode(metadata: &Metadata) -> Option<u32> {
    use std::os::unix::fs::PermissionsExt;

    Some(metadata.permissions().mode())
}

#[cfg(not(unix))]
fn unix_mode(_metadata: &Metadata) -> Option<u32> {
    None
}

fn client_config_capturing_server_fingerprint()
-> Result<(quinn::ClientConfig, Arc<Mutex<Option<String>>>)> {
    let server_fingerprint = Arc::new(Mutex::new(None));
    let crypto = rustls::ClientConfig::builder()
        .dangerous()
        .with_custom_certificate_verifier(ServerFingerprintVerifier::new(
            server_fingerprint.clone(),
        ))
        .with_no_client_auth();

    let config = quinn::ClientConfig::new(Arc::new(
        QuicClientConfig::try_from(crypto)
            .map_err(|error| Error::CryptoConfig(error.to_string()))?,
    ));
    Ok((config, server_fingerprint))
}

fn captured_server_fingerprint(fingerprint: &Arc<Mutex<Option<String>>>) -> Result<String> {
    fingerprint
        .lock()
        .map_err(|_| Error::CryptoConfig("server fingerprint capture lock poisoned".to_string()))?
        .clone()
        .ok_or_else(|| {
            Error::CryptoConfig("server certificate fingerprint was not captured".to_string())
        })
}

#[derive(Debug)]
struct ServerFingerprintVerifier {
    provider: Arc<CryptoProvider>,
    server_fingerprint: Arc<Mutex<Option<String>>>,
}

impl ServerFingerprintVerifier {
    fn new(server_fingerprint: Arc<Mutex<Option<String>>>) -> Arc<Self> {
        Arc::new(Self {
            provider: Arc::new(rustls::crypto::ring::default_provider()),
            server_fingerprint,
        })
    }
}

impl ServerCertVerifier for ServerFingerprintVerifier {
    fn verify_server_cert(
        &self,
        end_entity: &CertificateDer<'_>,
        _intermediates: &[CertificateDer<'_>],
        _server_name: &ServerName<'_>,
        _ocsp: &[u8],
        _now: UnixTime,
    ) -> std::result::Result<ServerCertVerified, rustls::Error> {
        let fingerprint = blake3::hash(end_entity.as_ref()).to_hex().to_string();
        *self.server_fingerprint.lock().map_err(|_| {
            rustls::Error::General("server fingerprint capture lock poisoned".to_string())
        })? = Some(fingerprint);
        Ok(ServerCertVerified::assertion())
    }

    fn verify_tls12_signature(
        &self,
        message: &[u8],
        cert: &CertificateDer<'_>,
        dss: &DigitallySignedStruct,
    ) -> std::result::Result<HandshakeSignatureValid, rustls::Error> {
        verify_tls12_signature(
            message,
            cert,
            dss,
            &self.provider.signature_verification_algorithms,
        )
    }

    fn verify_tls13_signature(
        &self,
        message: &[u8],
        cert: &CertificateDer<'_>,
        dss: &DigitallySignedStruct,
    ) -> std::result::Result<HandshakeSignatureValid, rustls::Error> {
        verify_tls13_signature(
            message,
            cert,
            dss,
            &self.provider.signature_verification_algorithms,
        )
    }

    fn supported_verify_schemes(&self) -> Vec<SignatureScheme> {
        self.provider
            .signature_verification_algorithms
            .supported_schemes()
    }
}

fn ensure_rustls_provider() {
    let _ = rustls::crypto::ring::default_provider().install_default();
}

pub fn config_dir() -> Result<PathBuf> {
    let base_dirs = BaseDirs::new().ok_or(Error::ConfigDirUnavailable)?;
    Ok(base_dirs.config_dir().join(CONFIG_DIR_NAME))
}

fn default_alias() -> String {
    std::env::var("HOSTNAME")
        .or_else(|_| std::env::var("COMPUTERNAME"))
        .ok()
        .filter(|value| !value.trim().is_empty())
        .unwrap_or_else(|| "fileferry-device".to_string())
}

fn expand_home_path(path: &str) -> Result<PathBuf> {
    if path == "~" {
        return Ok(BaseDirs::new()
            .ok_or(Error::ConfigDirUnavailable)?
            .home_dir()
            .to_path_buf());
    }

    if let Some(rest) = path.strip_prefix("~/") {
        return Ok(BaseDirs::new()
            .ok_or(Error::ConfigDirUnavailable)?
            .home_dir()
            .join(rest));
    }

    Ok(PathBuf::from(path))
}

fn normalized_fingerprint(fingerprint: String) -> Result<String> {
    let fingerprint = fingerprint.trim().to_ascii_lowercase();
    if fingerprint.len() != 64 || !fingerprint.chars().all(|char| char.is_ascii_hexdigit()) {
        return Err(Error::InvalidInput(
            "peer fingerprint must be a full 64-character hex BLAKE3 fingerprint".to_string(),
        ));
    }

    Ok(fingerprint)
}

fn validate_psk(psk: String) -> Result<String> {
    if psk.is_empty() {
        return Err(Error::InvalidInput("PSK must not be empty".to_string()));
    }

    Ok(psk)
}

fn psk_proof(
    psk: &str,
    challenge: &str,
    client_fingerprint: &str,
    protocol_version: u16,
) -> Result<String> {
    validate_psk(psk.to_string())?;
    let key = blake3::hash(psk.as_bytes());
    let mut message = Vec::new();
    message.extend_from_slice(PSK_PROOF_CONTEXT);
    message.push(0);
    message.extend_from_slice(challenge.as_bytes());
    message.push(0);
    message.extend_from_slice(client_fingerprint.as_bytes());
    message.push(0);
    message.extend_from_slice(protocol_version.to_string().as_bytes());
    Ok(blake3::keyed_hash(key.as_bytes(), &message)
        .to_hex()
        .to_string())
}

fn write_toml_file<T: Serialize>(path: &Path, value: &T) -> Result<()> {
    let bytes =
        toml::to_string_pretty(value).map_err(|error| Error::ConfigSerialize(error.to_string()))?;
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent).map_err(|source| Error::IoPath {
            path: parent.to_path_buf(),
            source,
        })?;
    }

    let temp_path = path.with_extension(format!("tmp-{}", Uuid::new_v4()));
    std::fs::write(&temp_path, bytes).map_err(|source| Error::IoPath {
        path: temp_path.clone(),
        source,
    })?;
    std::fs::rename(&temp_path, path).map_err(|source| Error::IoPath {
        path: path.to_path_buf(),
        source,
    })?;
    Ok(())
}

fn write_private_file(path: &Path, bytes: &[u8]) -> Result<()> {
    std::fs::write(path, bytes).map_err(|source| Error::IoPath {
        path: path.to_path_buf(),
        source,
    })?;

    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;

        let mut permissions = std::fs::metadata(path)
            .map_err(|source| Error::IoPath {
                path: path.to_path_buf(),
                source,
            })?
            .permissions();
        permissions.set_mode(0o600);
        std::fs::set_permissions(path, permissions).map_err(|source| Error::IoPath {
            path: path.to_path_buf(),
            source,
        })?;
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::sync::{Arc, Mutex};

    #[test]
    fn direct_peer_parses_socket_address() {
        let peer = DirectPeer::parse("127.0.0.1:53318").expect("address parses");

        assert_eq!(peer.address().to_string(), "127.0.0.1:53318");
        assert_eq!(peer.expected_fingerprint(), None);
    }

    #[test]
    fn direct_peer_accepts_expected_fingerprint() {
        let fingerprint = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
        let peer = DirectPeer::parse("127.0.0.1:53318")
            .expect("address parses")
            .with_expected_fingerprint(fingerprint)
            .expect("fingerprint parses");

        assert_eq!(peer.expected_fingerprint(), Some(fingerprint));
    }

    #[test]
    fn direct_peer_rejects_missing_port() {
        assert!(DirectPeer::parse("127.0.0.1").is_err());
    }

    #[test]
    fn send_request_requires_at_least_one_path() {
        let peer = DirectPeer::parse("127.0.0.1:53318").expect("address parses");

        assert!(SendRequest::new(peer, Vec::new()).is_err());
    }

    #[test]
    fn psk_secret_is_redacted_in_debug_and_serialization() {
        let secret = PskSecret::new("do-not-print").expect("psk accepted");

        assert_eq!(format!("{secret:?}"), "PskSecret(<redacted>)");
        assert_eq!(
            serde_json::to_string(&secret).expect("secret serializes"),
            r#""<redacted>""#
        );

        let peer = DirectPeer::parse("127.0.0.1:53318").expect("address parses");
        let request = SendRequest::new(peer, vec![PathBuf::from("file.txt")])
            .expect("send request")
            .with_psk("do-not-print")
            .expect("psk accepted");
        assert!(!format!("{request:?}").contains("do-not-print"));
    }

    #[test]
    fn validate_send_paths_rejects_empty_slice() {
        assert!(validate_send_paths(&[]).is_err());
    }

    #[tokio::test]
    async fn manifest_walks_directory_and_serializes_entries() {
        let temp = tempfile::tempdir().expect("tempdir");
        let root = temp.path().join("bundle");
        let nested = root.join("nested");
        let empty = nested.join("empty");
        tokio::fs::create_dir_all(&empty).await.expect("dirs");
        tokio::fs::write(root.join("a.txt"), b"alpha")
            .await
            .expect("file a");
        tokio::fs::write(root.join("zero.bin"), [])
            .await
            .expect("zero file");
        tokio::fs::write(nested.join("b.txt"), b"beta")
            .await
            .expect("file b");
        tokio::fs::write(nested.join("large.bin"), vec![9; IO_BUFFER_SIZE + 17])
            .await
            .expect("large file");

        let manifest = build_manifest(&[root]).await.expect("manifest");
        let json = serde_json::to_string(&manifest).expect("manifest serializes");
        let decoded: TransferManifest = serde_json::from_str(&json).expect("manifest decodes");
        let relative_paths = decoded
            .entries
            .iter()
            .map(|entry| entry.relative_path.clone())
            .collect::<Vec<_>>();

        assert_eq!(decoded.version, MANIFEST_VERSION);
        assert_eq!(
            relative_paths,
            vec![
                PathBuf::from("bundle"),
                PathBuf::from("bundle/a.txt"),
                PathBuf::from("bundle/nested"),
                PathBuf::from("bundle/nested/b.txt"),
                PathBuf::from("bundle/nested/empty"),
                PathBuf::from("bundle/nested/large.bin"),
                PathBuf::from("bundle/zero.bin"),
            ]
        );
        assert!(decoded.entries.iter().any(|entry| {
            entry.kind == ManifestEntryKind::Directory
                && entry.relative_path == Path::new("bundle/nested/empty")
        }));
        assert!(decoded.entries.iter().any(|entry| {
            entry.kind == ManifestEntryKind::File
                && entry.relative_path == Path::new("bundle/nested/b.txt")
                && entry.size == 4
                && entry.blake3.is_some()
        }));
        assert!(decoded.entries.iter().any(|entry| {
            entry.kind == ManifestEntryKind::File
                && entry.relative_path == Path::new("bundle/zero.bin")
                && entry.size == 0
                && entry.blake3.is_some()
        }));
        assert!(decoded.entries.iter().any(|entry| {
            entry.kind == ManifestEntryKind::File
                && entry.relative_path == Path::new("bundle/nested/large.bin")
                && entry.size == IO_BUFFER_SIZE as u64 + 17
                && entry.blake3.is_some()
        }));
    }

    #[test]
    fn safe_destination_path_rejects_unsafe_paths() {
        let dest = Path::new("/tmp/ferry-dest");

        assert!(safe_destination_path(dest, Path::new("../escape.txt")).is_err());
        assert!(safe_destination_path(dest, Path::new("/absolute.txt")).is_err());
        assert!(safe_destination_path(dest, Path::new("nested/CON")).is_err());
        assert!(safe_destination_path(dest, Path::new("nested\\escape.txt")).is_err());
        assert!(safe_destination_path(dest, Path::new("nested/ok.txt")).is_ok());
    }

    #[test]
    fn safe_destination_path_rejects_generated_escape_and_reserved_patterns() {
        let dest = Path::new("/tmp/ferry-dest");
        let unsafe_components = [
            "..",
            ".",
            "CON",
            "con.txt",
            "NUL",
            "COM1",
            "LPT9",
            "trailingspace ",
            "trailingdot.",
            "has:colon",
            "has\\backslash",
        ];

        for component in unsafe_components {
            assert!(
                safe_destination_path(dest, Path::new(component)).is_err(),
                "{component} should be rejected as a top-level path"
            );
            if component != "." {
                assert!(
                    safe_destination_path(dest, Path::new("safe").join(component).as_path())
                        .is_err(),
                    "{component} should be rejected as a nested path"
                );
            }
        }

        for component in ["alpha", "alpha-1", "alpha_1", "report.final.txt"] {
            let path = safe_destination_path(dest, Path::new("safe").join(component).as_path())
                .expect("safe generated path accepted");
            assert!(path.starts_with(dest));
        }
    }

    #[tokio::test]
    async fn resume_decision_skips_existing_matching_file() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest");
        tokio::fs::create_dir_all(&dest).await.expect("dest dir");
        tokio::fs::write(&source, b"same contents")
            .await
            .expect("source");
        tokio::fs::write(dest.join("source.txt"), b"same contents")
            .await
            .expect("dest file");
        let manifest = build_manifest(&[source]).await.expect("manifest");
        let entry = manifest.file_entries().next().expect("file entry");

        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("decision");

        assert_eq!(decision, ResumeDecision::Skip);
    }

    #[tokio::test]
    async fn resume_decision_returns_verified_chunk_offset() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source = temp.path().join("large.bin");
        let dest = temp.path().join("dest");
        tokio::fs::create_dir_all(&dest).await.expect("dest dir");
        let bytes = vec![42; (DEFAULT_CHUNK_SIZE as usize * 2) + 128];
        tokio::fs::write(&source, &bytes).await.expect("source");
        tokio::fs::write(
            dest.join("large.bin"),
            &bytes[..DEFAULT_CHUNK_SIZE as usize + 99],
        )
        .await
        .expect("partial");
        let manifest = build_manifest(&[source]).await.expect("manifest");
        let entry = manifest.file_entries().next().expect("file entry");

        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("decision");

        assert_eq!(decision, ResumeDecision::ResumeFrom(DEFAULT_CHUNK_SIZE));
    }

    #[tokio::test]
    async fn resume_decision_rejects_existing_file_with_mismatched_contents() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest");
        tokio::fs::create_dir_all(&dest).await.expect("dest dir");
        tokio::fs::write(&source, b"expected contents")
            .await
            .expect("source");
        tokio::fs::write(dest.join("source.txt"), b"different contents")
            .await
            .expect("conflicting dest file");
        let manifest = build_manifest(&[source]).await.expect("manifest");
        let entry = manifest.file_entries().next().expect("file entry");

        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("decision");

        assert!(matches!(decision, ResumeDecision::Conflict(_)));
    }

    #[tokio::test]
    async fn resume_decision_rejects_existing_file_larger_than_manifest_entry() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest");
        tokio::fs::create_dir_all(&dest).await.expect("dest dir");
        tokio::fs::write(&source, b"small").await.expect("source");
        tokio::fs::write(dest.join("source.txt"), b"larger destination")
            .await
            .expect("larger dest file");
        let manifest = build_manifest(&[source]).await.expect("manifest");
        let entry = manifest.file_entries().next().expect("file entry");

        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("decision");

        assert!(matches!(decision, ResumeDecision::Conflict(_)));
    }

    #[tokio::test]
    async fn resume_decision_handles_nested_partial_files_safely() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source_root = temp.path().join("bundle");
        let source_nested = source_root.join("nested");
        let dest = temp.path().join("dest");
        let dest_nested = dest.join("bundle/nested");
        tokio::fs::create_dir_all(&source_nested)
            .await
            .expect("source nested dir");
        tokio::fs::create_dir_all(&dest_nested)
            .await
            .expect("dest nested dir");
        let bytes = (0..((DEFAULT_CHUNK_SIZE as usize * 2) + 777))
            .map(|index| (index % 251) as u8)
            .collect::<Vec<_>>();
        let source_file = source_nested.join("large.bin");
        tokio::fs::write(&source_file, &bytes)
            .await
            .expect("source");
        let manifest = build_manifest(&[source_root]).await.expect("manifest");
        let entry = manifest
            .file_entries()
            .find(|entry| entry.relative_path == Path::new("bundle/nested/large.bin"))
            .expect("nested file entry");

        tokio::fs::write(
            dest_nested.join("large.bin"),
            &bytes[..DEFAULT_CHUNK_SIZE as usize + 99],
        )
        .await
        .expect("matching partial");
        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("matching partial decision");
        assert_eq!(decision, ResumeDecision::ResumeFrom(DEFAULT_CHUNK_SIZE));

        let mut mismatched = bytes[..DEFAULT_CHUNK_SIZE as usize + 99].to_vec();
        mismatched[0] ^= 0xff;
        tokio::fs::write(dest_nested.join("large.bin"), mismatched)
            .await
            .expect("mismatched partial");
        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("mismatched partial decision");
        assert!(matches!(decision, ResumeDecision::Conflict(_)));
    }

    #[tokio::test]
    async fn resume_decision_rejects_same_name_file_directory_conflicts() {
        let temp = tempfile::tempdir().expect("tempdir");
        let source = temp.path().join("source.txt");
        let dest = temp.path().join("dest");
        tokio::fs::create_dir_all(&dest).await.expect("dest dir");
        tokio::fs::write(&source, b"incoming file")
            .await
            .expect("source");
        tokio::fs::create_dir(dest.join("source.txt"))
            .await
            .expect("conflicting dest dir");
        let manifest = build_manifest(&[source]).await.expect("manifest");
        let entry = manifest.file_entries().next().expect("file entry");

        let decision = decide_resume(&dest, entry, manifest.chunk_size)
            .await
            .expect("decision");

        assert!(matches!(decision, ResumeDecision::Conflict(_)));
    }

    #[test]
    fn identity_is_loaded_after_generation() {
        let temp = tempfile::tempdir().expect("tempdir");
        let generated =
            NativeIdentity::load_or_generate_in(temp.path()).expect("identity generated");
        let loaded = NativeIdentity::load_or_generate_in(temp.path()).expect("identity loaded");

        assert_eq!(generated.fingerprint(), loaded.fingerprint());
    }

    #[test]
    fn app_config_round_trips_toml() {
        let temp = tempfile::tempdir().expect("tempdir");
        let path = temp.path().join("config.toml");
        let config = AppConfig {
            alias: "desk".to_string(),
            ..AppConfig::default()
        };

        config.save_to_path(&path).expect("config saved");
        let loaded = AppConfig::load_or_default_from(&path).expect("config loaded");

        assert_eq!(loaded.alias, "desk");
        assert_eq!(loaded.listen_port, 53317);
        assert!(loaded.trust.require_fingerprint);
    }

    #[test]
    fn app_config_redacts_psk_for_display_output() {
        let config = AppConfig {
            trust: TrustConfig {
                psk: "super-secret-psk".to_string(),
                ..TrustConfig::default()
            },
            ..AppConfig::default()
        };

        let redacted = config.to_redacted_toml_string().expect("config serializes");

        assert!(!redacted.contains("super-secret-psk"));
        assert!(redacted.contains(r#"psk = "<redacted>""#));
    }

    #[test]
    fn daemon_config_defaults_from_app_config_and_round_trips_toml() {
        let temp = tempfile::tempdir().expect("tempdir");
        let path = temp.path().join("daemon.toml");
        let app_config = AppConfig {
            quic_port: 54444,
            download_dir: temp.path().join("downloads").display().to_string(),
            ..AppConfig::default()
        };

        let defaulted =
            DaemonConfig::load_or_default_from(&path, &app_config).expect("daemon config");
        assert_eq!(
            defaulted.listen,
            SocketAddr::from(([0, 0, 0, 0], app_config.quic_port))
        );
        assert_eq!(defaulted.destination, temp.path().join("downloads"));

        let config = DaemonConfig {
            listen: SocketAddr::from(([127, 0, 0, 1], 53318)),
            destination: temp.path().join("daemon-dest"),
        };
        config.save_to_path(&path).expect("daemon config saved");
        let loaded =
            DaemonConfig::load_or_default_from(&path, &app_config).expect("daemon config loaded");

        assert_eq!(loaded, config);
    }

    #[test]
    fn trust_store_load_save_and_forget_round_trip() {
        let temp = tempfile::tempdir().expect("tempdir");
        let path = temp.path().join("known_peers.toml");
        let fingerprint = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
        let mut store = TrustStore::default();

        store
            .trust_fingerprint(fingerprint)
            .expect("fingerprint trusted");
        store.save_to_path(&path).expect("trust store saved");
        let mut loaded = TrustStore::load_or_default_from(&path).expect("trust store loaded");

        assert_eq!(loaded.records().count(), 1);
        assert_eq!(loaded.peers[fingerprint].trust_state, TrustState::Trusted);
        assert!(loaded.forget(fingerprint));
        assert_eq!(loaded.records().count(), 0);
    }

    #[test]
    fn trust_store_rejects_short_fingerprint_without_discovery_lookup() {
        let mut store = TrustStore::default();

        assert!(store.trust_fingerprint("9a4f2c").is_err());
    }

    #[test]
    fn trust_store_pins_direct_address_to_fingerprint() {
        let fingerprint = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef";
        let address = SocketAddr::from(([192, 168, 1, 42], 53318));
        let mut store = TrustStore::default();

        store
            .trust_direct_address(fingerprint, address)
            .expect("direct address trusted");

        assert!(store.is_trusted_fingerprint(fingerprint));
        assert_eq!(
            store.trusted_fingerprint_for_address(address),
            Some(fingerprint)
        );
        assert!(store.peers[fingerprint].addresses.contains(&address));
        assert!(store.peers[fingerprint].transports.contains("quic"));
        assert_eq!(store.peers[fingerprint].trust_state, TrustState::Trusted);
    }

    #[test]
    fn transfer_events_serialize_with_stable_event_names() {
        let event = TransferEvent::Progress {
            direction: TransferDirection::Send,
            file_name: "bundle/a.txt".to_string(),
            bytes_done: 5,
            bytes_total: 9,
        };

        let json = serde_json::to_value(&event).expect("event serializes");

        assert_eq!(json["event"], "progress");
        assert_eq!(json["direction"], "send");
        assert_eq!(json["file_name"], "bundle/a.txt");
        assert_eq!(json["bytes_done"], 5);
        assert_eq!(json["bytes_total"], 9);
    }

    #[test]
    fn direct_protocol_hello_has_stable_golden_json() {
        let hello = DirectProtocolHello {
            protocol_version: 1,
            min_protocol_version: 1,
            client_fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            psk: false,
        };

        let json = serde_json::to_string(&hello).expect("hello serializes");

        assert_eq!(
            json,
            r#"{"protocol_version":1,"min_protocol_version":1,"client_fingerprint":"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef","psk":false}"#
        );
    }

    #[test]
    fn direct_protocol_response_has_stable_golden_json() {
        let response = DirectProtocolResponse::accept(1);

        let json = serde_json::to_string(&response).expect("response serializes");

        assert_eq!(
            json,
            r#"{"accepted":true,"protocol_version":1,"psk_challenge":null,"error":null}"#
        );
    }

    #[test]
    fn direct_protocol_decodes_pre_psk_negotiation_frames() {
        let hello: DirectProtocolHello = serde_json::from_str(
            r#"{"protocol_version":1,"min_protocol_version":1,"client_fingerprint":"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"}"#,
        )
        .expect("old hello decodes");
        assert!(!hello.psk);

        let response: DirectProtocolResponse =
            serde_json::from_str(r#"{"accepted":true,"protocol_version":1,"error":null}"#)
                .expect("old response decodes");
        assert_eq!(response, DirectProtocolResponse::accept(1));
    }

    #[test]
    fn direct_protocol_negotiates_supported_overlap() {
        let hello = DirectProtocolHello {
            protocol_version: 3,
            min_protocol_version: 1,
            client_fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            psk: false,
        };

        let response = negotiate_direct_protocol(&hello, None);

        assert_eq!(response, DirectProtocolResponse::accept(1));
    }

    #[test]
    fn direct_protocol_rejects_incompatible_versions() {
        let too_new = DirectProtocolHello {
            protocol_version: 3,
            min_protocol_version: 2,
            client_fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            psk: false,
        };
        let too_old = DirectProtocolHello {
            protocol_version: 0,
            min_protocol_version: 0,
            client_fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            psk: false,
        };

        assert!(!negotiate_direct_protocol(&too_new, None).accepted);
        assert!(!negotiate_direct_protocol(&too_old, None).accepted);
    }

    #[test]
    fn direct_protocol_requires_matching_psk_mode() {
        let no_psk = DirectProtocolHello {
            protocol_version: 1,
            min_protocol_version: 1,
            client_fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            psk: false,
        };
        let with_psk = DirectProtocolHello {
            psk: true,
            ..no_psk.clone()
        };

        assert!(!negotiate_direct_protocol(&no_psk, Some("secret")).accepted);
        assert!(!negotiate_direct_protocol(&with_psk, None).accepted);

        let accepted = negotiate_direct_protocol(&with_psk, Some("secret"));
        assert!(accepted.accepted);
        assert!(accepted.psk_challenge.is_some());
    }

    #[test]
    fn transfer_manifest_has_stable_golden_json() {
        let manifest = TransferManifest {
            version: MANIFEST_VERSION,
            session_id: Uuid::parse_str("00000000-0000-0000-0000-000000000001")
                .expect("uuid parses"),
            chunk_size: DEFAULT_CHUNK_SIZE,
            entries: vec![ManifestEntry {
                relative_path: PathBuf::from("bundle/a.txt"),
                kind: ManifestEntryKind::File,
                size: 5,
                blake3: Some(
                    "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef".to_string(),
                ),
                chunks: vec![
                    "abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789".to_string(),
                ],
                unix_mode: Some(0o100644),
                modified_unix_ms: Some(1_700_000_000_000),
            }],
        };

        let json = serde_json::to_string(&manifest).expect("manifest serializes");

        assert_eq!(
            json,
            r#"{"version":1,"session_id":"00000000-0000-0000-0000-000000000001","chunk_size":1048576,"entries":[{"relative_path":"bundle/a.txt","kind":"file","size":5,"blake3":"0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef","chunks":["abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789"],"unix_mode":33188,"modified_unix_ms":1700000000000}]}"#
        );
    }

    #[test]
    fn peer_registry_merges_observations_by_fingerprint() {
        let mut registry = PeerRegistry::new();
        let fingerprint = "abcdef1234567890";
        let first = PeerObservation::new(
            fingerprint,
            SocketAddr::from(([192, 168, 1, 10], 53318)),
            100,
        )
        .with_alias("desk")
        .with_hostname("desk.local")
        .with_transport("quic");
        let second = PeerObservation::new(
            fingerprint,
            SocketAddr::from(([192, 168, 1, 11], 53318)),
            200,
        )
        .with_alias("workstation")
        .with_transport("quic");

        registry.observe(first).expect("first observation");
        registry.observe(second).expect("second observation");
        let record = registry
            .get_by_fingerprint(fingerprint)
            .expect("record by fingerprint");

        assert_eq!(registry.records().count(), 1);
        assert!(record.aliases.contains("desk"));
        assert!(record.aliases.contains("workstation"));
        assert!(record.hostnames.contains("desk.local"));
        assert_eq!(record.addresses.len(), 2);
        assert_eq!(record.first_seen_unix_ms, 100);
        assert_eq!(record.last_seen_unix_ms, 200);
    }

    #[test]
    fn peer_registry_looks_up_unique_fingerprint_prefix_alias_and_hostname() {
        let mut registry = PeerRegistry::new();
        registry
            .observe(
                PeerObservation::new(
                    "abcdef1234567890",
                    SocketAddr::from(([192, 168, 1, 10], 53318)),
                    100,
                )
                .with_alias("desk")
                .with_hostname("desk.local"),
            )
            .expect("first observation");
        registry
            .observe(
                PeerObservation::new(
                    "123456abcdef7890",
                    SocketAddr::from(([192, 168, 1, 20], 53318)),
                    100,
                )
                .with_alias("laptop"),
            )
            .expect("second observation");

        assert_eq!(
            registry
                .lookup("abcdef")
                .map(|record| record.fingerprint.as_str()),
            Some("abcdef1234567890")
        );
        assert_eq!(
            registry
                .lookup("desk")
                .map(|record| record.fingerprint.as_str()),
            Some("abcdef1234567890")
        );
        assert_eq!(
            registry
                .lookup("desk.local")
                .map(|record| record.fingerprint.as_str()),
            Some("abcdef1234567890")
        );
        assert!(registry.lookup("missing").is_none());
    }

    #[test]
    fn peer_registry_rejects_ambiguous_lookup_hints() {
        let mut registry = PeerRegistry::new();
        registry
            .observe(
                PeerObservation::new(
                    "abcdef1234567890",
                    SocketAddr::from(([192, 168, 1, 10], 53318)),
                    100,
                )
                .with_alias("desk"),
            )
            .expect("first observation");
        registry
            .observe(
                PeerObservation::new(
                    "abcdef9999999999",
                    SocketAddr::from(([192, 168, 1, 11], 53318)),
                    100,
                )
                .with_alias("desk"),
            )
            .expect("second observation");

        assert!(registry.lookup("abcdef").is_none());
        assert!(registry.lookup("desk").is_none());
        assert_eq!(
            registry
                .lookup("abcdef1234567890")
                .map(|record| record.fingerprint.as_str()),
            Some("abcdef1234567890")
        );
        match registry.lookup_detail("desk") {
            PeerLookup::Ambiguous(records) => assert_eq!(records.len(), 2),
            other => panic!("expected ambiguous duplicate-alias lookup, got {other:?}"),
        }
        assert!(matches!(
            registry.lookup_detail("missing"),
            PeerLookup::Missing
        ));
    }

    #[test]
    fn native_announcement_builds_expected_txt_properties() {
        let announcement = NativeAnnouncement {
            alias: "Stephen MBP".to_string(),
            fingerprint: "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
                .to_string(),
            quic_port: 53318,
            listen_port: Some(53317),
        };

        let service = announcement.service_info().expect("service info");

        assert_eq!(service.get_type(), NATIVE_SERVICE_TYPE);
        assert!(
            service
                .get_fullname()
                .starts_with("stephen-mbp-0123456789ab.")
        );
        assert_eq!(service.get_property_val_str("pv"), Some("1"));
        assert_eq!(service.get_property_val_str("minpv"), Some("1"));
        assert_eq!(
            service.get_property_val_str("fp"),
            Some("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef")
        );
        assert_eq!(service.get_property_val_str("alias"), Some("Stephen MBP"));
        assert_eq!(service.get_property_val_str("transports"), Some("quic"));
        assert_eq!(service.get_property_val_str("quic_port"), Some("53318"));
        assert_eq!(service.get_property_val_str("listen_port"), Some("53317"));
    }

    #[test]
    fn resolved_native_service_merges_into_registry() {
        let properties = [
            ("pv", "1"),
            ("minpv", "1"),
            (
                "fp",
                "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
            ),
            ("alias", "desk"),
            ("transports", "quic"),
            ("quic_port", "53318"),
        ];
        let service = ServiceInfo::new(
            NATIVE_SERVICE_TYPE,
            "desk-0123456789ab",
            "desk.local.",
            "192.168.1.42",
            53318,
            &properties[..],
        )
        .expect("service info")
        .as_resolved_service();
        let mut registry = PeerRegistry::new();

        observe_resolved_service(&mut registry, &service).expect("observation");

        let record = registry.lookup("desk").expect("record by alias");
        assert_eq!(
            record.fingerprint,
            "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
        );
        assert_eq!(
            record.preferred_quic_address(),
            Some(SocketAddr::from(([192, 168, 1, 42], 53318)))
        );
    }

    #[test]
    fn resolved_native_service_ignores_incompatible_protocol_ranges() {
        let properties = [
            ("pv", "3"),
            ("minpv", "2"),
            (
                "fp",
                "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef",
            ),
            ("alias", "desk"),
            ("transports", "quic"),
            ("quic_port", "53318"),
        ];
        let service = ServiceInfo::new(
            NATIVE_SERVICE_TYPE,
            "desk-0123456789ab",
            "desk.local.",
            "192.168.1.42",
            53318,
            &properties[..],
        )
        .expect("service info")
        .as_resolved_service();
        let mut registry = PeerRegistry::new();

        observe_resolved_service(&mut registry, &service).expect("observation");

        assert_eq!(registry.records().count(), 0);
    }

    #[tokio::test]
    async fn direct_quic_loopback_sends_one_file() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let receive_progress = Arc::new(Mutex::new(Vec::new()));
        let receive_progress_log = receive_progress.clone();
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &recv_identity,
                |event| {
                    receive_progress_log
                        .lock()
                        .expect("progress lock")
                        .push(event);
                },
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![file_path]).expect("send request is valid");
        let send_progress = Arc::new(Mutex::new(Vec::new()));
        let send_progress_log = send_progress.clone();
        let send_summary = send_direct_file(&send_request, &identity, |event| {
            send_progress_log.lock().expect("progress lock").push(event);
        })
        .await
        .expect("file sent");
        let receive_summary = server.await.expect("server joined").expect("file received");

        let received = tokio::fs::read(dest_dir.path().join("hello.txt"))
            .await
            .expect("received file readable");
        assert_eq!(received, b"hello from ferry");
        assert_eq!(send_summary.bytes, receive_summary.bytes);
        assert_eq!(send_summary.blake3, receive_summary.blake3);
        let send_progress = send_progress.lock().expect("progress lock");
        let receive_progress = receive_progress.lock().expect("progress lock");
        assert!(matches!(
            send_progress.first(),
            Some(TransferEvent::SessionStarted {
                direction: TransferDirection::Send,
                ..
            })
        ));
        assert!(
            send_progress
                .iter()
                .any(|event| matches!(event, TransferEvent::Progress { .. }))
        );
        assert!(
            send_progress
                .iter()
                .any(|event| matches!(event, TransferEvent::SessionFinished { .. }))
        );
        assert!(matches!(
            receive_progress.first(),
            Some(TransferEvent::SessionStarted {
                direction: TransferDirection::Receive,
                ..
            })
        ));
        assert!(
            receive_progress
                .iter()
                .any(|event| matches!(event, TransferEvent::Progress { .. }))
        );
        assert!(
            receive_progress
                .iter()
                .any(|event| matches!(event, TransferEvent::SessionFinished { .. }))
        );
    }

    #[tokio::test]
    async fn direct_transfer_accepts_expected_receiver_fingerprint() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let sender_identity_dir = tempfile::tempdir().expect("sender identity tempdir");
        let receiver_identity_dir = tempfile::tempdir().expect("receiver identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let sender_identity = NativeIdentity::load_or_generate_in(sender_identity_dir.path())
            .expect("sender identity");
        let receiver_identity = NativeIdentity::load_or_generate_in(receiver_identity_dir.path())
            .expect("receiver identity");
        let expected_fingerprint = receiver_identity.fingerprint().to_string();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &receiver_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::from_address(recv_addr)
            .with_expected_fingerprint(expected_fingerprint)
            .expect("expected fingerprint accepted");
        let send_request = SendRequest::new(peer, vec![file_path]).expect("send request is valid");
        let send_summary = send_direct_file(&send_request, &sender_identity, |_| {})
            .await
            .expect("file sent");
        let receive_summary = server.await.expect("server joined").expect("file received");

        let received = tokio::fs::read(dest_dir.path().join("hello.txt"))
            .await
            .expect("received file readable");
        assert_eq!(received, b"hello from ferry");
        assert_eq!(send_summary.bytes, receive_summary.bytes);
        assert_eq!(send_summary.blake3, receive_summary.blake3);
    }

    #[tokio::test]
    async fn direct_transfer_confirms_unpinned_receiver_before_payload() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let sender_identity_dir = tempfile::tempdir().expect("sender identity tempdir");
        let receiver_identity_dir = tempfile::tempdir().expect("receiver identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let sender_identity = NativeIdentity::load_or_generate_in(sender_identity_dir.path())
            .expect("sender identity");
        let receiver_identity = NativeIdentity::load_or_generate_in(receiver_identity_dir.path())
            .expect("receiver identity");
        let expected_fingerprint = receiver_identity.fingerprint().to_string();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &receiver_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::from_address(recv_addr);
        let send_request = SendRequest::new(peer, vec![file_path]).expect("send request is valid");
        let callback_seen = Arc::new(AtomicBool::new(false));
        let callback_seen_send = callback_seen.clone();
        let send_summary = send_direct_file_with_control_and_trust(
            &send_request,
            &sender_identity,
            TransferControl::new(),
            |_| {},
            |fingerprint| {
                callback_seen_send.store(true, Ordering::SeqCst);
                assert_eq!(fingerprint, expected_fingerprint);
                Ok(())
            },
        )
        .await
        .expect("file sent after trust callback");
        let receive_summary = server.await.expect("server joined").expect("file received");

        assert!(callback_seen.load(Ordering::SeqCst));
        assert_eq!(send_summary.bytes, receive_summary.bytes);
        assert_eq!(send_summary.blake3, receive_summary.blake3);
    }

    #[tokio::test]
    async fn direct_transfer_rejects_unexpected_receiver_fingerprint_before_payload() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let sender_identity_dir = tempfile::tempdir().expect("sender identity tempdir");
        let receiver_identity_dir = tempfile::tempdir().expect("receiver identity tempdir");
        let other_identity_dir = tempfile::tempdir().expect("other identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let sender_identity = NativeIdentity::load_or_generate_in(sender_identity_dir.path())
            .expect("sender identity");
        let receiver_identity = NativeIdentity::load_or_generate_in(receiver_identity_dir.path())
            .expect("receiver identity");
        let other_identity =
            NativeIdentity::load_or_generate_in(other_identity_dir.path()).expect("other identity");
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &receiver_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::from_address(recv_addr)
            .with_expected_fingerprint(other_identity.fingerprint().to_string())
            .expect("expected fingerprint accepted");
        let send_request = SendRequest::new(peer, vec![file_path]).expect("send request is valid");
        let error = send_direct_file(&send_request, &sender_identity, |_| {})
            .await
            .expect_err("fingerprint mismatch should reject send");

        assert!(matches!(error, Error::PeerFingerprintMismatch { .. }));
        let server_error = server
            .await
            .expect("server joined")
            .expect_err("server closed");
        assert!(matches!(
            server_error,
            Error::Connection(_) | Error::NoIncomingConnection
        ));
        assert!(
            !tokio::fs::try_exists(dest_dir.path().join("hello.txt"))
                .await
                .expect("destination checked")
        );
    }

    #[tokio::test]
    async fn direct_transfer_accepts_matching_psk_before_payload() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let receive_request = ReceiveRequest::new(recv_addr)
            .with_psk("correct horse battery staple")
            .expect("receiver psk accepted");
        let server = tokio::spawn(async move {
            receive_direct_file(&receive_request, dest_path, &recv_identity, |_| {}).await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![file_path])
            .expect("send request is valid")
            .with_psk("correct horse battery staple")
            .expect("sender psk accepted");
        let send_summary = send_direct_file(&send_request, &identity, |_| {})
            .await
            .expect("file sent");
        let receive_summary = server.await.expect("server joined").expect("file received");

        let received = tokio::fs::read(dest_dir.path().join("hello.txt"))
            .await
            .expect("received file readable");
        assert_eq!(received, b"hello from ferry");
        assert_eq!(send_summary.bytes, receive_summary.bytes);
    }

    #[tokio::test]
    async fn direct_transfer_rejects_missing_psk_before_payload() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let receive_request = ReceiveRequest::new(recv_addr)
            .with_psk("receiver secret")
            .expect("receiver psk accepted");
        let server = tokio::spawn(async move {
            receive_direct_file(&receive_request, dest_path, &recv_identity, |_| {}).await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![file_path]).expect("send request is valid");
        let error = send_direct_file(&send_request, &identity, |_| {})
            .await
            .expect_err("missing psk should reject send");

        assert!(matches!(error, Error::Protocol(_)));
        let _ = server.await.expect("server joined");
        assert!(
            !tokio::fs::try_exists(dest_dir.path().join("hello.txt"))
                .await
                .expect("destination checked")
        );
    }

    #[tokio::test]
    async fn direct_transfer_rejects_wrong_psk_before_payload() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let file_path = source_dir.path().join("hello.txt");
        tokio::fs::write(&file_path, b"hello from ferry")
            .await
            .expect("source file written");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let receive_request = ReceiveRequest::new(recv_addr)
            .with_psk("receiver secret")
            .expect("receiver psk accepted");
        let server = tokio::spawn(async move {
            receive_direct_file(&receive_request, dest_path, &recv_identity, |_| {}).await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![file_path])
            .expect("send request is valid")
            .with_psk("wrong secret")
            .expect("sender psk accepted");
        let error = send_direct_file(&send_request, &identity, |_| {})
            .await
            .expect_err("wrong psk should reject send");

        assert!(matches!(error, Error::Authentication(_)));
        assert!(!error.to_string().contains("wrong secret"));
        assert!(!error.to_string().contains("receiver secret"));
        let server_error = server
            .await
            .expect("server joined")
            .expect_err("server should reject wrong psk");
        assert!(matches!(
            server_error,
            Error::Authentication(_) | Error::Write(_)
        ));
        assert!(
            !tokio::fs::try_exists(dest_dir.path().join("hello.txt"))
                .await
                .expect("destination checked")
        );
    }

    #[tokio::test]
    async fn direct_quic_loopback_sends_directory_and_resumes_partial_file() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let bundle = source_dir.path().join("bundle");
        let nested = bundle.join("nested");
        tokio::fs::create_dir_all(&nested)
            .await
            .expect("source dirs");
        tokio::fs::write(nested.join("small.txt"), b"small")
            .await
            .expect("small file");
        let large_bytes = vec![7; (DEFAULT_CHUNK_SIZE as usize * 2) + 17];
        tokio::fs::write(bundle.join("large.bin"), &large_bytes)
            .await
            .expect("large file");

        let dest_bundle = dest_dir.path().join("bundle");
        tokio::fs::create_dir_all(&dest_bundle)
            .await
            .expect("dest bundle");
        tokio::fs::write(
            dest_bundle.join("large.bin"),
            &large_bytes[..DEFAULT_CHUNK_SIZE as usize + 5],
        )
        .await
        .expect("partial large");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &recv_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![bundle]).expect("send request is valid");
        let send_summary = send_direct_file(&send_request, &identity, |_| {})
            .await
            .expect("directory sent");
        let receive_summary = server
            .await
            .expect("server joined")
            .expect("directory received");

        let received_large = tokio::fs::read(dest_bundle.join("large.bin"))
            .await
            .expect("large file readable");
        let received_small = tokio::fs::read(dest_bundle.join("nested/small.txt"))
            .await
            .expect("small file readable");
        assert_eq!(received_large, large_bytes);
        assert_eq!(received_small, b"small");
        assert_eq!(send_summary.bytes, receive_summary.bytes);
        assert!(
            receive_summary
                .files
                .iter()
                .any(|file| file.status == TransferFileStatus::Resumed)
        );
    }

    #[tokio::test]
    async fn direct_quic_loopback_rejects_file_blocking_incoming_directory() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let bundle = source_dir.path().join("bundle");
        let nested = bundle.join("nested");
        tokio::fs::create_dir_all(&nested)
            .await
            .expect("source dirs");
        tokio::fs::write(nested.join("payload.txt"), b"payload")
            .await
            .expect("source file");

        tokio::fs::create_dir_all(dest_dir.path().join("bundle"))
            .await
            .expect("dest bundle dir");
        let conflicting_path = dest_dir.path().join("bundle/nested");
        tokio::fs::write(&conflicting_path, b"do not overwrite")
            .await
            .expect("conflicting dest file");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &recv_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![bundle]).expect("send request is valid");
        let send_result = send_direct_file(&send_request, &identity, |_| {}).await;
        let receive_result = server.await.expect("server joined");

        assert!(send_result.is_err());
        assert!(receive_result.is_err());
        let conflict = tokio::fs::read(&conflicting_path)
            .await
            .expect("conflicting dest file remains readable");
        assert_eq!(conflict, b"do not overwrite");
        assert!(!conflicting_path.is_dir());
    }

    #[tokio::test]
    async fn direct_quic_loopback_cancels_send_and_does_not_finalize_partial_file() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let file_path = source_dir.path().join("payload.bin");
        tokio::fs::write(&file_path, vec![3; IO_BUFFER_SIZE * 64])
            .await
            .expect("source file written");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);

        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &recv_identity,
                |_| {},
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request =
            SendRequest::new(peer, vec![file_path.clone()]).expect("send request is valid");
        let send_control = TransferControl::new();
        let cancel_on_progress = send_control.clone();
        let send_events = Arc::new(Mutex::new(Vec::new()));
        let send_events_log = send_events.clone();
        let send_result =
            send_direct_file_with_control(&send_request, &identity, send_control, |event| {
                if matches!(event, TransferEvent::Progress { .. }) {
                    cancel_on_progress.cancel();
                }
                send_events_log.lock().expect("events lock").push(event);
            })
            .await;

        assert!(matches!(send_result, Err(Error::TransferCancelled)));

        let receive_result = tokio::time::timeout(Duration::from_secs(5), server)
            .await
            .expect("receiver should finish after sender cancellation")
            .expect("server joined");
        assert!(receive_result.is_err());

        assert!(!dest_dir.path().join("payload.bin").exists());
        assert!(
            send_events
                .lock()
                .expect("events lock")
                .iter()
                .any(|event| matches!(event, TransferEvent::SessionCancelled { .. }))
        );
    }

    #[tokio::test]
    async fn direct_quic_loopback_cleans_partial_file_when_directory_receive_is_cancelled() {
        let source_dir = tempfile::tempdir().expect("source tempdir");
        let dest_dir = tempfile::tempdir().expect("dest tempdir");
        let identity_dir = tempfile::tempdir().expect("identity tempdir");
        let bundle = source_dir.path().join("bundle");
        let nested = bundle.join("nested");
        tokio::fs::create_dir_all(&nested)
            .await
            .expect("source dirs");
        tokio::fs::write(bundle.join("small.txt"), b"small")
            .await
            .expect("small file");
        tokio::fs::write(nested.join("payload.bin"), vec![5; IO_BUFFER_SIZE * 128])
            .await
            .expect("large source file");

        let identity =
            NativeIdentity::load_or_generate_in(identity_dir.path()).expect("identity generated");
        let recv_identity = identity.clone();
        let reserved_socket =
            std::net::UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).expect("udp bind");
        let recv_addr = reserved_socket.local_addr().expect("local addr");
        drop(reserved_socket);

        let receive_control = TransferControl::new();
        let cancel_receive = receive_control.clone();
        let receive_events = Arc::new(Mutex::new(Vec::new()));
        let receive_events_log = receive_events.clone();
        let dest_path = dest_dir.path().to_path_buf();
        let server = tokio::spawn(async move {
            receive_direct_file_with_control(
                &ReceiveRequest::new(recv_addr),
                dest_path,
                &recv_identity,
                receive_control,
                |event| {
                    if let TransferEvent::Progress { file_name, .. } = &event
                        && file_name == "bundle/nested/payload.bin"
                    {
                        cancel_receive.cancel();
                    }
                    receive_events_log.lock().expect("events lock").push(event);
                },
            )
            .await
        });

        tokio::time::sleep(Duration::from_millis(100)).await;

        let peer = DirectPeer::parse(&recv_addr.to_string()).expect("peer parses");
        let send_request = SendRequest::new(peer, vec![bundle]).expect("send request is valid");
        let send_result = send_direct_file(&send_request, &identity, |_| {}).await;
        let receive_result = tokio::time::timeout(Duration::from_secs(5), server)
            .await
            .expect("receiver should finish after cancellation")
            .expect("server joined");

        assert!(send_result.is_err());
        assert!(matches!(receive_result, Err(Error::TransferCancelled)));
        assert!(
            receive_events
                .lock()
                .expect("events lock")
                .iter()
                .any(|event| matches!(event, TransferEvent::SessionCancelled { .. }))
        );
        assert!(
            !tokio::fs::try_exists(dest_dir.path().join("bundle/nested/payload.bin"))
                .await
                .expect("payload path checked")
        );
        let part_files = std::fs::read_dir(dest_dir.path().join("bundle/nested"))
            .expect("nested dest dir exists")
            .filter_map(|entry| entry.ok())
            .filter(|entry| entry.file_name().to_string_lossy().contains(".ferry-part"))
            .count();
        assert_eq!(part_files, 0);
    }
}