Reconnect before input after local sleep

.gitignore

@@ -1,3 +1,4 @@
 /target/
 **/*.rs.bk
 .DS_Store
+vscode-extension/*.vsix

Cargo.lock

@@ -436,7 +436,7 @@ dependencies = [
 
 [[package]]
 name = "dosh"
-version = "0.1.4"
+version = "1.0.0-rc35"
 dependencies = [
  "anyhow",
  "base64",
@@ -447,6 +447,7 @@ dependencies = [
  "crossterm",
  "dirs",
  "ed25519-dalek",
+ "filetime",
  "hkdf",
  "hmac",
  "libc",
@@ -577,6 +578,16 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "filetime"
+version = "0.2.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c287a33c7f0a620c38e641e7f60827713987b3c0f26e8ddc9462cc69cf75759"
+dependencies = [
+ "cfg-if",
+ "libc",
+]
+
 [[package]]
 name = "foldhash"
 version = "0.1.5"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dosh"
-version = "0.1.4"
+version = "1.0.0-rc35"
 edition = "2024"
 license = "MIT"
 
@@ -14,6 +14,7 @@ clap = { version = "4.5", features = ["derive"] }
 crossterm = "0.28"
 dirs = "5.0"
 ed25519-dalek = "2.1"
+filetime = "0.2"
 hkdf = "0.12"
 hmac = "0.12"
 libc = "0.2"

Makefile

@@ -1,4 +1,4 @@
-.PHONY: build test fmt install package-release package-release-linux package-release-windows publish-release bench-report bench-local bench-local-json bench-docker-ssh bench-docker-mosh fuzz-smoke fuzz-deep soak-local tui-harness
+.PHONY: build test fmt clippy release-check 1.0-check reconnect-check hostile-network-check persistence-check package-check install package-release package-release-linux package-release-windows publish-release bench-report bench-local bench-local-json bench-docker-ssh bench-docker-mosh fuzz-smoke fuzz-deep soak-local tui-harness
 
 build:
 	cargo build --release
@@ -9,6 +9,37 @@ test:
 fmt:
 	cargo fmt
 
+clippy:
+	cargo clippy --all-targets -- -D warnings
+
+release-check:
+	cargo fmt --check
+	sh -n install.sh scripts/*.sh
+	cargo clippy --all-targets -- -D warnings
+	cargo test
+	$(MAKE) tui-harness
+
+1.0-check: release-check reconnect-check hostile-network-check persistence-check package-check
+
+reconnect-check:
+	cargo test --test integration_smoke resume_updates_udp_endpoint_for_roaming -- --nocapture
+	DOSH_SOAK_SECONDS=$${DOSH_SOAK_SECONDS:-300} cargo test --test integration_smoke sleep_roaming_soak_30m -- --ignored --nocapture
+
+hostile-network-check:
+	cargo test --test hostile_network -- --nocapture
+	DOSH_BADNET_SOAK_SECONDS=$${DOSH_BADNET_SOAK_SECONDS:-300} cargo test --test hostile_network bad_network_tui_work_soak_30m -- --ignored --nocapture
+
+persistence-check:
+	cargo test --test integration_smoke session_survives_server_restart_same_shell_and_screen -- --nocapture
+	cargo test --test integration_smoke multiple_persistent_named_sessions_survive_restart_independently -- --nocapture
+
+package-check:
+	$(MAKE) package-release-linux
+	$(MAKE) package-release-windows
+	sh scripts/verify-release-artifacts.sh \
+		target/dosh-release/dosh-linux-x86_64.tar.gz \
+		target/dosh-release/dosh-windows-x86_64.zip
+
 install:
 	sh install.sh --from-current
 

README.md

@@ -1,32 +1,31 @@
 # Dosh
 
-Dosh is an encrypted remote terminal for fast reconnecting shells. It is meant
-to replace Mosh and day-to-day interactive SSH sessions.
+Dosh is an encrypted remote terminal for fast reconnecting shells.
 
-It runs a `dosh-server` on the remote machine and a `dosh` client locally. The
-first setup can use SSH. After that, Dosh can attach over encrypted UDP with
-cached credentials, keep terminal sessions alive, reconnect after network
-changes, and forward TCP ports.
+It runs a `dosh-server` on a Unix-like host and a `dosh` client on macOS,
+Linux, or Windows. Setup can use SSH, then Dosh connects over encrypted UDP,
+keeps sessions alive across disconnects, supports terminal apps, and can carry
+TCP forwarding, file copy, and VS Code Remote-SSH streams.
 
 ## Support
 
 - Client: macOS, Linux, Windows
-- Server: Unix-like systems with PTYs
+- Server: Linux and other Unix-like systems with PTYs
+- Default UDP port: `50000`
 - Windows: client only
-- UDP port: one configured server port, default `50000`
 
-Dosh is not an SCP/SFTP client and does not implement X11 forwarding. Windows
-is client-only.
+Dosh is meant to replace Mosh and everyday interactive SSH sessions. It does
+not currently include SFTP, X11 forwarding, or a Windows server.
 
 ## Install
 
-Server and client on Unix/macOS:
+Unix/macOS server and client:
 
 ```sh
 curl -fsSL https://git.palav.dev/Palav/dosh/raw/branch/main/install.sh | sh -s -- both --repo https://git.palav.dev/Palav/dosh.git --port 50000
 ```
 
-Client only on Unix/macOS:
+Unix/macOS client only:
 
 ```sh
 curl -fsSL https://git.palav.dev/Palav/dosh/raw/branch/main/install.sh | sh -s -- client --repo https://git.palav.dev/Palav/dosh.git
@@ -38,30 +37,74 @@ Windows client:
 irm https://git.palav.dev/Palav/dosh/raw/branch/main/install.ps1 | iex
 ```
 
-## Commands
+## Use
 
 ```sh
-dosh setup HOST          # import SSH config and trust the Dosh host key
-dosh HOST                # connect
-dosh HOST COMMAND        # connect and run a command
-dosh update              # update Dosh
-dosh status HOST         # show remote tmux sessions and Dosh service status
-dosh restart HOST        # restart dosh-server and show service status
-dosh doctor HOST         # check config and connectivity
-dosh recover HOST        # clear cached attach state and re-check
+dosh setup HOST
+dosh HOST
+dosh HOST COMMAND
+dosh update
+dosh update --client|--server|--both
 ```
 
-Examples:
+Useful commands:
 
 ```sh
-dosh palav
-dosh palav tm
-dosh forward palav -L 8080:127.0.0.1:80
-dosh forward palav -D 1080
-dosh forward palav -R 2222:127.0.0.1:22
+dosh exec HOST COMMAND
+dosh cp SRC DST
+dosh ls host:path
+dosh cat host:path
+dosh mkdir host:path
+dosh rm [-r] host:path
+dosh forward HOST -L 8080:127.0.0.1:80
+dosh forward HOST -D 1080
+dosh forward HOST -R 2222:127.0.0.1:22
+dosh status HOST
+dosh doctor HOST
+dosh recover HOST
+dosh restart HOST
 ```
 
-Agent forwarding is opt-in with `-A` and must be enabled on the server.
+Agent forwarding is opt-in with `-A` and must also be enabled on the server.
+File copy must be enabled by the server config.
+
+## Tracing
+
+For terminal/reconnect bugs, run a client with:
+
+```sh
+dosh trace HOST
+```
+
+The client log path is printed before the session starts. To choose it:
+
+```sh
+dosh trace --client-log /tmp/dosh-client.log HOST
+```
+
+Summarize collected traces with:
+
+```sh
+dosh trace report HOST --client-log /tmp/dosh-client.log
+```
+
+When `HOST` is given, Dosh fetches `/tmp/dosh-server.log` over SSH before
+building the report. Set `DOSH_TRACE=/tmp/dosh-server.log` on `dosh-server` for
+matching server events. Trace byte prefixes are enabled for `dosh trace`, so use
+it only for short reproductions.
+
+## VS Code
+
+Dosh can carry VS Code Remote-SSH through its transport:
+
+```sh
+dosh vscode setup HOST
+dosh vscode HOST /remote/path
+```
+
+This creates a managed SSH config entry using `ProxyCommand dosh proxy-stdio`.
+VS Code still uses Remote-SSH and its normal remote server; Dosh carries the
+SSH byte stream.
 
 ## Config
 
@@ -75,8 +118,35 @@ Common client settings:
 
 ```toml
 default_session = "new"
-auth_preference = "native,ssh"
 predict = true
 cache_attach_tickets = true
 disconnect_status = true
 ```
+
+Example host entry:
+
+```toml
+[prod]
+ssh = "prod"
+ssh_config = "prod" # OpenSSH alias for IdentityFile, ProxyJump, SendEnv, etc.
+dosh_host = "prod.example.com"
+port = 50000
+```
+
+`ProxyJump` and `ProxyCommand` can be used for SSH setup, but the Dosh UDP
+endpoint still has to be reachable directly from the client. Set `dosh_host` to
+the reachable UDP hostname or IP when it differs from the SSH alias target.
+
+## Rust Library
+
+Dosh exposes a Rust transport for encrypted, reconnecting application streams.
+Use `dosh::client::DoshClient` and `dosh::server::DoshServer` for the normal
+native-auth path. Use `dosh::transport::DoshTransport` only when you already
+own session setup and authentication.
+
+Runnable examples:
+
+```text
+examples/sdk_echo_client.rs
+examples/sdk_echo_server.rs
+```

build.rs

@@ -1,3 +1,4 @@
+use std::env;
 use std::process::Command;
 
 fn git(args: &[&str]) -> Option<String> {
@@ -12,14 +13,29 @@ fn git(args: &[&str]) -> Option<String> {
 fn main() {
     println!("cargo:rerun-if-changed=.git/HEAD");
     println!("cargo:rerun-if-changed=.git/index");
+    println!("cargo:rerun-if-env-changed=DOSH_BUILD_GIT_HASH");
+    println!("cargo:rerun-if-env-changed=DOSH_BUILD_COMMIT_DATE");
+    println!("cargo:rerun-if-env-changed=DOSH_BUILD_GIT_DIRTY");
 
-    let hash = git(&["rev-parse", "--short=12", "HEAD"]).unwrap_or_else(|| "unknown".into());
-    let date = git(&["show", "-s", "--format=%cs", "HEAD"]).unwrap_or_else(|| "unknown".into());
-    let dirty = Command::new("git")
-        .args(["diff", "--quiet", "--ignore-submodules", "--"])
-        .status()
-        .map(|status| if status.success() { "" } else { "+dirty" })
-        .unwrap_or("");
+    let hash = env::var("DOSH_BUILD_GIT_HASH")
+        .ok()
+        .filter(|value| !value.is_empty())
+        .or_else(|| git(&["rev-parse", "--short=12", "HEAD"]))
+        .unwrap_or_else(|| "unknown".into());
+    let date = env::var("DOSH_BUILD_COMMIT_DATE")
+        .ok()
+        .filter(|value| !value.is_empty())
+        .or_else(|| git(&["show", "-s", "--format=%cs", "HEAD"]))
+        .unwrap_or_else(|| "unknown".into());
+    let dirty = match env::var("DOSH_BUILD_GIT_DIRTY").ok().as_deref() {
+        Some("1" | "true" | "yes" | "+dirty") => "+dirty",
+        Some(_) => "",
+        None => Command::new("git")
+            .args(["diff", "--quiet", "--ignore-submodules", "--"])
+            .status()
+            .map(|status| if status.success() { "" } else { "+dirty" })
+            .unwrap_or(""),
+    };
 
     println!("cargo:rustc-env=DOSH_GIT_HASH={hash}{dirty}");
     println!("cargo:rustc-env=DOSH_COMMIT_DATE={date}");

examples/sdk_echo_client.rs

@@ -0,0 +1,50 @@
+use anyhow::{Result, bail};
+use dosh::client::DoshClient;
+use dosh::transport::{SessionEvent, TransportEvent};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let mut args = std::env::args().skip(1);
+    let host = args.next().unwrap_or_else(|| "server".to_string());
+    let message = args.collect::<Vec<_>>().join(" ");
+    let message = if message.is_empty() {
+        "hello from dosh".to_string()
+    } else {
+        message
+    };
+
+    let client = DoshClient::load()?;
+    let mut transport = client
+        .connect(host)
+        .service("echo")
+        .connect()
+        .await?
+        .into_transport();
+    let stream = transport.open_service("echo").await?;
+
+    loop {
+        match transport.recv().await? {
+            SessionEvent::Stream(TransportEvent::OpenOk { stream_id, .. })
+                if stream_id == stream =>
+            {
+                transport.send(stream, message.as_bytes().to_vec()).await?;
+            }
+            SessionEvent::Stream(TransportEvent::Data(data)) if data.stream_id == stream => {
+                for chunk in data.chunks {
+                    print!("{}", String::from_utf8_lossy(&chunk));
+                }
+                println!();
+                transport.close(stream).await?;
+                return Ok(());
+            }
+            SessionEvent::Stream(TransportEvent::OpenReject { reason, .. }) => {
+                bail!("server rejected echo stream: {reason}");
+            }
+            SessionEvent::Stream(_)
+            | SessionEvent::Ping
+            | SessionEvent::Pong
+            | SessionEvent::Ignored => {}
+        }
+        transport.maintenance().await?;
+    }
+}

examples/sdk_echo_server.rs

@@ -0,0 +1,37 @@
+use anyhow::Result;
+use dosh::server::{DoshServer, DoshServerConfig, DoshServerEvent};
+use dosh::transport::{SessionEvent, TransportEvent};
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let config = DoshServerConfig::default().service("echo")?;
+    let mut server = DoshServer::bind(config).await?;
+    eprintln!("listening on {}", server.local_addr()?);
+
+    loop {
+        match server.recv().await? {
+            DoshServerEvent::Accepted(client) => {
+                eprintln!(
+                    "accepted user={} session={} conn={:?}",
+                    client.user, client.session, client.conn_id
+                );
+            }
+            DoshServerEvent::Session {
+                conn_id,
+                event: SessionEvent::Stream(TransportEvent::Open(open)),
+            } => {
+                server.accept_stream(conn_id, open.stream_id).await?;
+            }
+            DoshServerEvent::Session {
+                conn_id,
+                event: SessionEvent::Stream(TransportEvent::Data(data)),
+            } => {
+                for chunk in data.chunks {
+                    server.send(conn_id, data.stream_id, chunk).await?;
+                }
+            }
+            DoshServerEvent::Session { .. } | DoshServerEvent::Ignored => {}
+        }
+        server.maintenance().await?;
+    }
+}

install.ps1

@@ -1,7 +1,7 @@
 param(
     [ValidateSet("client")]
     [string]$Role = $(if ($env:DOSH_ROLE) { $env:DOSH_ROLE } else { "client" }),
-    [string]$Repo = $env:DOSH_REPO,
+    [string]$Repo = $(if ($env:DOSH_REPO) { $env:DOSH_REPO } else { "https://git.palav.dev/Palav/dosh.git" }),
     [string]$Server = $env:DOSH_SERVER,
     [string]$DoshHost = $(if ($env:DOSH_HOST) { $env:DOSH_HOST } else { $env:DOSH_DOSH_HOST }),
     [int]$Port = $(if ($env:DOSH_PORT) { [int]$env:DOSH_PORT } else { 50000 }),
@@ -141,6 +141,20 @@ function Verify-ArchiveVersion($ExtractDir, $Url) {
     }
 }
 
+function Install-Binary($Source, $Destination) {
+    $dir = Split-Path -Parent $Destination
+    $name = Split-Path -Leaf $Destination
+    $tmp = Join-Path $dir ".$name.tmp.$PID"
+    Copy-Item $Source $tmp -Force
+    try {
+        Move-Item $tmp $Destination -Force
+    }
+    catch {
+        Remove-Item $tmp -Force -ErrorAction SilentlyContinue
+        throw
+    }
+}
+
 $bindir = Join-Path $Prefix "bin"
 $configDir = Join-Path $HOME ".config\dosh"
 New-Item -ItemType Directory -Force -Path $bindir, $configDir | Out-Null
@@ -168,9 +182,9 @@ function Install-Prebuilt {
             if (-not $found) {
                 throw "prebuilt archive missing $bin"
             }
-            Copy-Item $found.FullName (Join-Path $bindir $bin) -Force
+            Install-Binary $found.FullName (Join-Path $bindir $bin)
         }
-        Copy-Item (Join-Path $bindir "dosh-client.exe") (Join-Path $bindir "dosh.exe") -Force
+        Install-Binary (Join-Path $bindir "dosh-client.exe") (Join-Path $bindir "dosh.exe")
         return $true
     }
     catch {
@@ -202,9 +216,9 @@ function Install-FromSource {
     try {
         Push-Location $src
         cargo build --release --bin dosh-client --bin dosh-bench
-        Copy-Item "target\release\dosh-client.exe" (Join-Path $bindir "dosh-client.exe") -Force
-        Copy-Item "target\release\dosh-client.exe" (Join-Path $bindir "dosh.exe") -Force
-        Copy-Item "target\release\dosh-bench.exe" (Join-Path $bindir "dosh-bench.exe") -Force
+        Install-Binary "target\release\dosh-client.exe" (Join-Path $bindir "dosh-client.exe")
+        Install-Binary "target\release\dosh-client.exe" (Join-Path $bindir "dosh.exe")
+        Install-Binary "target\release\dosh-bench.exe" (Join-Path $bindir "dosh-bench.exe")
     }
     finally {
         Pop-Location

install.sh

@@ -12,11 +12,7 @@ start_server=1
 force_config=0
 update_cache="${DOSH_UPDATE_CACHE:-$HOME/.cache/dosh/source}"
 quiet="${DOSH_UPDATE_QUIET:-0}"
-if [ "${DOSH_UPDATE_QUIET:-0}" = "1" ] && [ "${DOSH_BINARY_REQUIRED:-0}" != "1" ]; then
-  use_prebuilt=0
-else
-  use_prebuilt="${DOSH_USE_PREBUILT:-1}"
-fi
+use_prebuilt="${DOSH_USE_PREBUILT:-1}"
 binary_url="${DOSH_BINARY_URL:-}"
 binary_base="${DOSH_BINARY_BASE:-}"
 binary_name="${DOSH_BINARY_NAME:-}"
@@ -230,13 +226,26 @@ find_extracted_binary() {
   find "$1" -type f -name "$2" 2>/dev/null | sed -n '1p'
 }
 
+install_binary() {
+  src="$1"
+  dst="$2"
+  dst_dir="$(dirname "$dst")"
+  dst_base="$(basename "$dst")"
+  tmp="$dst_dir/.$dst_base.tmp.$$"
+  install -m 0755 "$src" "$tmp"
+  if ! mv -f "$tmp" "$dst"; then
+    rm -f "$tmp"
+    return 1
+  fi
+}
+
 install_extracted_binary() {
   found="$(find_extracted_binary "$1" "$2")"
   if [ -z "$found" ]; then
     echo "prebuilt archive missing $2" >&2
     return 1
   fi
-  install -m 0755 "$found" "$3"
+  install_binary "$found" "$3"
 }
 
 sha256_file() {
@@ -333,7 +342,7 @@ try_install_prebuilt() {
     install_extracted_binary "$tmpdir/extract" dosh-auth "$bindir/dosh-auth" || return 1
   fi
   if found_bench="$(find_extracted_binary "$tmpdir/extract" dosh-bench)" && [ -n "$found_bench" ]; then
-    install -m 0755 "$found_bench" "$bindir/dosh-bench"
+    install_binary "$found_bench" "$bindir/dosh-bench"
   fi
   return 0
 }
@@ -392,14 +401,14 @@ install_from_source() {
     fi
   fi
 
-  install -m 0755 target/release/dosh-client "$bindir/dosh-client"
+  install_binary target/release/dosh-client "$bindir/dosh-client"
   ln -sf dosh-client "$bindir/dosh"
   if [ "$role" = "server" ] || [ "$role" = "both" ]; then
-    install -m 0755 target/release/dosh-server "$bindir/dosh-server"
-    install -m 0755 target/release/dosh-auth "$bindir/dosh-auth"
+    install_binary target/release/dosh-server "$bindir/dosh-server"
+    install_binary target/release/dosh-auth "$bindir/dosh-auth"
   fi
   if [ -f target/release/dosh-bench ]; then
-    install -m 0755 target/release/dosh-bench "$bindir/dosh-bench"
+    install_binary target/release/dosh-bench "$bindir/dosh-bench"
   fi
 }
 
@@ -410,14 +419,14 @@ write_systemd_service() {
   else
     cat >"$systemd_user_dir/dosh-server.service" <<EOF
 [Unit]
-Description=Dosh server
+Description=dosh dormant shell server
 After=network-online.target
 Wants=network-online.target
 
 [Service]
 Type=simple
 ExecStart=$bindir/dosh-server serve
-Restart=on-failure
+Restart=always
 RestartSec=1
 KillMode=process
 
@@ -479,7 +488,8 @@ EOF
     mkdir -p "$systemd_user_dir"
     write_systemd_service
     if [ "$start_server" -eq 1 ] && systemctl --user daemon-reload >/dev/null 2>&1; then
-      systemctl --user enable --now dosh-server.service
+      systemctl --user enable dosh-server.service
+      systemctl --user restart dosh-server.service
     fi
   elif [ "$start_server" -eq 1 ]; then
     nohup "$bindir/dosh-server" serve >"$data_dir/dosh-server.log" 2>&1 &
@@ -547,8 +557,8 @@ EOF
     fi
     cat >"$hosts_config" <<EOF
 # Example:
-# [homelab]
-# ssh = "homelab"
+# [server]
+# ssh = "server"
 # dosh_host = "server.example.com"
 # port = 50000
 # default_command = "tm"

packaging/systemd/dosh-server.service

@@ -6,18 +6,9 @@ Wants=network-online.target
 [Service]
 Type=simple
 ExecStart=%h/.local/bin/dosh-server serve
-Restart=on-failure
+Restart=always
 RestartSec=1
 KillMode=process
-NoNewPrivileges=true
-PrivateTmp=true
-ProtectSystem=strict
-ProtectHome=read-only
-ReadWritePaths=%h/.config/dosh %h/.local/share/dosh
-RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
-RestrictRealtime=true
-LockPersonality=true
-MemoryDenyWriteExecute=true
 
 [Install]
 WantedBy=default.target

scripts/bench-local.sh

@@ -67,6 +67,7 @@ cleanup() {
     kill "$server_pid" 2>/dev/null || true
     wait "$server_pid" 2>/dev/null || true
   fi
+  pkill -f "$server_bin hold --runtime-dir $home/sessions/run" 2>/dev/null || true
   rm -rf "$home"
 }
 trap cleanup EXIT INT TERM
@@ -86,6 +87,7 @@ scrollback = 5000
 auth_ttl_secs = 30
 attach_ticket_ttl_secs = 3600
 allow_attach_tickets = true
+persist_sessions = false
 client_timeout_secs = 60
 retransmit_window = 256
 default_input_mode = "read-write"

scripts/package-release.sh

@@ -52,6 +52,22 @@ else
   release_dir="target/release"
 fi
 
+if command -v git >/dev/null 2>&1 && git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+  if [ -z "${DOSH_BUILD_GIT_HASH:-}" ]; then
+    export DOSH_BUILD_GIT_HASH="$(git rev-parse --short=12 HEAD)"
+  fi
+  if [ -z "${DOSH_BUILD_COMMIT_DATE:-}" ]; then
+    export DOSH_BUILD_COMMIT_DATE="$(git show -s --format=%cs HEAD)"
+  fi
+  if [ -z "${DOSH_BUILD_GIT_DIRTY+x}" ]; then
+    if git diff --quiet --ignore-submodules --; then
+      export DOSH_BUILD_GIT_DIRTY=0
+    else
+      export DOSH_BUILD_GIT_DIRTY=1
+    fi
+  fi
+fi
+
 if [ "$os" = "windows" ]; then
   if [ -n "$target" ]; then
     cargo build --release --target "$target" --bin dosh-client --bin dosh-bench

scripts/publish-gitea-release.sh

@@ -99,6 +99,21 @@ fi
 
 web_repo="${base%/}/${repo}"
 failed=0
+artifact_version() {
+  artifact="$1"
+  case "$artifact" in
+    *.tar.gz)
+      tar -xOf "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *.zip)
+      unzip -p "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *)
+      return 1
+      ;;
+  esac
+}
+
 for artifact in target/dosh-release/dosh-linux-*.tar.gz target/dosh-release/dosh-macos-*.tar.gz target/dosh-release/dosh-windows-*.zip; do
   [ -f "$artifact" ] || continue
   name="$(basename "$artifact")"
@@ -107,6 +122,11 @@ for artifact in target/dosh-release/dosh-linux-*.tar.gz target/dosh-release/dosh
       continue
       ;;
   esac
+  actual="$(artifact_version "$artifact" || true)"
+  if [ "$actual" != "$version" ]; then
+    echo "skipping stale artifact $name: version ${actual:-unknown}, expected $version" >&2
+    continue
+  fi
   url="$web_repo/releases/download/$tag/$name"
   if curl -fsSI "$url" >/dev/null; then
     echo "verified $url"

scripts/tui-harness.sh

@@ -8,6 +8,8 @@ for test_name in \
   live_output_forwards_terminal_control_sequences \
   tui_control_sequences_survive_transport_verbatim \
   unicode_output_survives_transport \
+  tui_graph_glyphs_survive_fast_repaints_without_snapshot_substitution \
+  btop_style_graph_output_stays_raw_when_retransmit_history_overflows \
   large_tui_paint_is_delivered_in_mtu_safe_frames \
   resume_snapshot_preserves_alternate_screen_mode
 do

scripts/upload-gitea-release.sh

@@ -32,6 +32,21 @@ token="${GITEA_TOKEN:-}"
 title="${GITEA_TITLE:-$tag}"
 expected_version="${tag#v}"
 
+artifact_version() {
+  artifact="$1"
+  case "$artifact" in
+    *.tar.gz)
+      tar -xOf "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *.zip)
+      unzip -p "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *)
+      return 1
+      ;;
+  esac
+}
+
 if [ -z "$token" ] && [ -f "$HOME/.config/dosh/gitea-token" ]; then
   token="$(tr -d '\r\n' <"$HOME/.config/dosh/gitea-token")"
 fi
@@ -52,6 +67,11 @@ if [ "$#" -eq 0 ]; then
         continue
         ;;
     esac
+    actual="$(artifact_version "$artifact" || true)"
+    if [ "$actual" != "$expected_version" ]; then
+      echo "skipping $artifact: version ${actual:-unknown}, expected $expected_version" >&2
+      continue
+    fi
     if [ -f "$artifact.sha256" ]; then
       set -- "$@" "$artifact" "$artifact.sha256"
     else
@@ -103,21 +123,6 @@ delete_existing_asset() {
     done
 }
 
-artifact_version() {
-  artifact="$1"
-  case "$artifact" in
-    *.tar.gz)
-      tar -xOf "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
-      ;;
-    *.zip)
-      unzip -p "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
-      ;;
-    *)
-      return 1
-      ;;
-  esac
-}
-
 verify_release_artifact_version() {
   artifact="$1"
   name="$(basename "$artifact")"

scripts/verify-release-artifacts.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env sh
+set -eu
+
+repo_root="$(CDPATH= cd -- "$(dirname -- "$0")/.." && pwd)"
+cd "$repo_root"
+
+version="$(sed -n 's/^version = "\(.*\)"/\1/p' Cargo.toml | sed -n '1p')"
+out_dir="${DOSH_PACKAGE_DIR:-target/dosh-release}"
+
+artifact_version() {
+  artifact="$1"
+  case "$artifact" in
+    *.tar.gz)
+      tar -xOf "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *.zip)
+      unzip -p "$artifact" dosh/VERSION 2>/dev/null | tr -d '\r\n'
+      ;;
+    *)
+      return 1
+      ;;
+  esac
+}
+
+if [ "$#" -gt 0 ]; then
+  artifacts="$*"
+else
+  artifacts="$out_dir/dosh-linux-x86_64.tar.gz $out_dir/dosh-macos-aarch64.tar.gz $out_dir/dosh-windows-x86_64.zip"
+fi
+
+failed=0
+for artifact in $artifacts; do
+  if [ ! -f "$artifact" ]; then
+    echo "missing release artifact: $artifact" >&2
+    failed=1
+    continue
+  fi
+  if [ ! -f "$artifact.sha256" ]; then
+    echo "missing release checksum: $artifact.sha256" >&2
+    failed=1
+  fi
+  actual="$(artifact_version "$artifact" || true)"
+  if [ "$actual" != "$version" ]; then
+    echo "artifact version mismatch: $artifact has ${actual:-unknown}, expected $version" >&2
+    failed=1
+  fi
+done
+
+exit "$failed"

src/client.rs

@@ -0,0 +1,443 @@
+use crate::config::{
+    ClientConfig, HostConfig, expand_tilde, load_client_config, load_hosts_config,
+};
+use crate::crypto;
+use crate::native::{
+    self, EnvVar, ForwardingKind, ForwardingRequest, KnownHostStatus, NativeClientHello,
+    derive_native_session_key, generate_native_ephemeral, sign_user_auth_with_private_key,
+    supported_user_key_algorithms, trust_host, verify_known_host, verify_server_hello,
+};
+use crate::protocol::{
+    self, AttachReject, CLIENT_TO_SERVER, NativeAuthOkBody, NativeClientHelloBody,
+    NativeServerHelloBody, NativeUserAuthBody, PacketKind, SERVER_TO_CLIENT,
+};
+use crate::ssh_agent;
+use crate::transport::{DoshTransport, SessionRole, SessionTransportConfig, TransportConfig};
+use crate::udp::{recv_udp_retrying_transient, send_udp_retrying_transient};
+use anyhow::{Context, Result, anyhow, bail};
+use std::net::{SocketAddr, ToSocketAddrs};
+use std::path::PathBuf;
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+use tokio::net::UdpSocket;
+
+#[derive(Debug, Clone)]
+pub struct DoshClient {
+    config: ClientConfig,
+    hosts: crate::config::HostsConfig,
+}
+
+impl DoshClient {
+    pub fn load() -> Result<Self> {
+        Ok(Self {
+            config: load_client_config(None)?,
+            hosts: load_hosts_config(None)?,
+        })
+    }
+
+    pub fn load_from_paths(
+        client_config: Option<PathBuf>,
+        hosts_config: Option<PathBuf>,
+    ) -> Result<Self> {
+        Ok(Self {
+            config: load_client_config(client_config)?,
+            hosts: load_hosts_config(hosts_config)?,
+        })
+    }
+
+    pub fn with_config(config: ClientConfig, hosts: crate::config::HostsConfig) -> Self {
+        Self { config, hosts }
+    }
+
+    pub fn connect(&self, host: impl Into<String>) -> DoshClientBuilder {
+        DoshClientBuilder::new(self.clone(), host.into())
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct DoshClientBuilder {
+    client: DoshClient,
+    host: String,
+    services: Vec<String>,
+    identity_files: Vec<PathBuf>,
+    session: Option<String>,
+    user: Option<String>,
+    udp_host: Option<String>,
+    udp_port: Option<u16>,
+    trust_on_first_use: Option<bool>,
+    use_ssh_agent: Option<bool>,
+    timeout: Option<Duration>,
+    env: Vec<EnvVar>,
+}
+
+impl DoshClientBuilder {
+    pub fn new(client: DoshClient, host: String) -> Self {
+        Self {
+            client,
+            host,
+            services: Vec::new(),
+            identity_files: Vec::new(),
+            session: None,
+            user: None,
+            udp_host: None,
+            udp_port: None,
+            trust_on_first_use: None,
+            use_ssh_agent: None,
+            timeout: None,
+            env: Vec::new(),
+        }
+    }
+
+    pub fn service(mut self, name: impl Into<String>) -> Self {
+        self.services.push(name.into());
+        self
+    }
+
+    pub fn services(mut self, names: impl IntoIterator<Item = impl Into<String>>) -> Self {
+        self.services.extend(names.into_iter().map(Into::into));
+        self
+    }
+
+    pub fn identity_file(mut self, path: impl Into<PathBuf>) -> Self {
+        self.identity_files.push(path.into());
+        self
+    }
+
+    pub fn session(mut self, session: impl Into<String>) -> Self {
+        self.session = Some(session.into());
+        self
+    }
+
+    pub fn user(mut self, user: impl Into<String>) -> Self {
+        self.user = Some(user.into());
+        self
+    }
+
+    pub fn udp_host(mut self, host: impl Into<String>) -> Self {
+        self.udp_host = Some(host.into());
+        self
+    }
+
+    pub fn udp_port(mut self, port: u16) -> Self {
+        self.udp_port = Some(port);
+        self
+    }
+
+    pub fn trust_on_first_use(mut self, trust: bool) -> Self {
+        self.trust_on_first_use = Some(trust);
+        self
+    }
+
+    pub fn use_ssh_agent(mut self, value: bool) -> Self {
+        self.use_ssh_agent = Some(value);
+        self
+    }
+
+    pub fn timeout(mut self, timeout: Duration) -> Self {
+        self.timeout = Some(timeout);
+        self
+    }
+
+    pub fn env(mut self, name: impl Into<String>, value: impl Into<String>) -> Self {
+        self.env.push(EnvVar {
+            name: name.into(),
+            value: value.into(),
+        });
+        self
+    }
+
+    pub async fn connect(self) -> Result<ConnectedDoshClient> {
+        let host_config = self
+            .client
+            .hosts
+            .hosts
+            .get(&self.host)
+            .cloned()
+            .unwrap_or_default();
+        let raw_server = host_config.ssh.clone().unwrap_or_else(|| self.host.clone());
+        let requested_user = self
+            .user
+            .clone()
+            .or_else(|| host_config.user.clone())
+            .or_else(|| user_from_destination(&raw_server))
+            .or_else(|| std::env::var("USER").ok())
+            .unwrap_or_else(|| "unknown".to_string());
+        let udp_host = self
+            .udp_host
+            .clone()
+            .or_else(|| host_config.dosh_host.clone())
+            .or_else(|| self.client.config.dosh_host.clone())
+            .unwrap_or_else(|| destination_host(&raw_server));
+        let udp_port = self
+            .udp_port
+            .or(host_config.port)
+            .unwrap_or(self.client.config.dosh_port);
+        let peer_addr = resolve_addr(&udp_host, udp_port)?;
+        let timeout = self.timeout.unwrap_or_else(|| {
+            Duration::from_millis(self.client.config.native_auth_timeout_ms.max(1))
+        });
+        let session = self.session.unwrap_or_else(default_sdk_session);
+        let requested_forwardings = self
+            .services
+            .iter()
+            .map(|service| {
+                Ok(ForwardingRequest {
+                    kind: ForwardingKind::Local,
+                    bind_host: None,
+                    listen_port: 0,
+                    target_host: Some(crate::transport::service_target(service)?),
+                    target_port: Some(0),
+                })
+            })
+            .collect::<Result<Vec<_>>>()?;
+        let socket = UdpSocket::bind("0.0.0.0:0").await?;
+        let (client_secret, client_public) = generate_native_ephemeral();
+        let hello = NativeClientHello {
+            protocol_version: native::NATIVE_PROTOCOL_VERSION,
+            client_random: crypto::random_32(),
+            client_ephemeral_public: client_public,
+            requested_host: self.host.clone(),
+            requested_user,
+            requested_session: session.clone(),
+            requested_mode: "forward-only".to_string(),
+            terminal_size: (80, 24),
+            supported_aead: vec!["chacha20poly1305".to_string()],
+            supported_user_key_algorithms: supported_user_key_algorithms(),
+            cached_host_key_fingerprint: None,
+            attach_ticket_envelope: None,
+            requested_env: self.env,
+        };
+        let packet = protocol::encode_plain(
+            PacketKind::NativeClientHello,
+            [0u8; 16],
+            1,
+            0,
+            &protocol::to_body(&NativeClientHelloBody {
+                hello: hello.clone(),
+            })?,
+        )?;
+        send_udp_retrying_transient(&socket, &packet, peer_addr, timeout).await?;
+
+        let mut buf = vec![0u8; 65535];
+        let (n, _) = recv_udp_retrying_transient(&socket, &mut buf, timeout).await?;
+        let packet = protocol::decode(&buf[..n])?;
+        if packet.header.kind != PacketKind::NativeServerHello {
+            if packet.header.kind == PacketKind::AttachReject {
+                let reject: AttachReject = protocol::from_body(&packet.body)?;
+                bail!("native auth rejected: {}", reject.reason);
+            }
+            bail!("native auth received unexpected server response");
+        }
+        let server_hello: NativeServerHelloBody = protocol::from_body(&packet.body)?;
+        verify_server_hello(&hello, &server_hello.hello)?;
+        verify_or_trust_host(
+            &self.client.config,
+            &self.host,
+            &server_hello.hello.host_key,
+            self.trust_on_first_use,
+        )?;
+
+        let session_key = derive_native_session_key(
+            &client_secret,
+            server_hello.hello.server_ephemeral_public,
+            &hello,
+            &server_hello.hello,
+        )?;
+        let auth = sign_auth(
+            &self.client.config,
+            &host_config,
+            &hello,
+            &server_hello.hello,
+            requested_forwardings,
+            self.identity_files,
+            self.use_ssh_agent,
+        )?;
+        let mut pending_id = [0u8; 16];
+        pending_id.copy_from_slice(&server_hello.hello.auth_challenge[..16]);
+        let auth_packet = protocol::encode_encrypted(
+            PacketKind::NativeUserAuth,
+            pending_id,
+            2,
+            1,
+            &session_key,
+            CLIENT_TO_SERVER,
+            &protocol::to_body(&NativeUserAuthBody { auth })?,
+        )?;
+        send_udp_retrying_transient(&socket, &auth_packet, peer_addr, timeout).await?;
+        let (n, _) = recv_udp_retrying_transient(&socket, &mut buf, timeout).await?;
+        let packet = protocol::decode(&buf[..n])?;
+        if packet.header.kind != PacketKind::NativeAuthOk {
+            if packet.header.kind == PacketKind::AttachReject {
+                let reject: AttachReject = protocol::from_body(&packet.body)?;
+                bail!("native auth rejected: {}", reject.reason);
+            }
+            bail!("native auth received unexpected auth response");
+        }
+        let plain = protocol::decrypt_body(&packet, &session_key, SERVER_TO_CLIENT)?;
+        let ok: NativeAuthOkBody = protocol::from_body(&plain)?;
+        let transport = DoshTransport::new_owned(
+            socket,
+            SessionTransportConfig {
+                role: SessionRole::Client,
+                conn_id: ok.ok.client_id,
+                session_key: ok.ok.session_key,
+                peer_addr,
+                initial_send_seq: 2,
+                initial_ack: ok.ok.initial_seq,
+                stream: TransportConfig::default(),
+            },
+        );
+        Ok(ConnectedDoshClient {
+            host: self.host,
+            session: ok.ok.session,
+            transport,
+        })
+    }
+}
+
+pub struct ConnectedDoshClient {
+    pub host: String,
+    pub session: String,
+    pub transport: DoshTransport,
+}
+
+impl ConnectedDoshClient {
+    pub fn into_transport(self) -> DoshTransport {
+        self.transport
+    }
+}
+
+fn verify_or_trust_host(
+    config: &ClientConfig,
+    host: &str,
+    host_key: &native::HostPublicKey,
+    trust_override: Option<bool>,
+) -> Result<()> {
+    let known_hosts = expand_tilde(&config.known_hosts);
+    match verify_known_host(&known_hosts, host, host_key)? {
+        KnownHostStatus::Trusted => Ok(()),
+        KnownHostStatus::Unknown if trust_override.unwrap_or(config.trust_on_first_use) => {
+            trust_host(&known_hosts, host, host_key, "sdk-tofu", false)?;
+            Ok(())
+        }
+        KnownHostStatus::Unknown => Err(anyhow!(
+            "Dosh host key for {host} is not trusted; run `dosh trust {host}` first or enable trust_on_first_use"
+        )),
+        KnownHostStatus::Mismatch { expected, actual } => Err(anyhow!(
+            "Dosh host key mismatch for {host}: expected {expected}, got {actual}"
+        )),
+    }
+}
+
+fn sign_auth(
+    config: &ClientConfig,
+    host_config: &HostConfig,
+    hello: &NativeClientHello,
+    server_hello: &native::NativeServerHello,
+    requested_forwardings: Vec<ForwardingRequest>,
+    explicit_identity_files: Vec<PathBuf>,
+    use_ssh_agent: Option<bool>,
+) -> Result<native::NativeUserAuth> {
+    let use_agent = use_ssh_agent.unwrap_or(config.use_ssh_agent);
+    let mut errors = Vec::new();
+    if use_agent {
+        match ssh_agent::sign_user_auth_with_agent(
+            hello,
+            server_hello,
+            requested_forwardings.clone(),
+        ) {
+            Ok(auth) => return Ok(auth),
+            Err(err) => errors.push(format!("ssh-agent: {err:#}")),
+        }
+    }
+
+    let mut paths = explicit_identity_files;
+    if paths.is_empty() {
+        paths.extend(config.identity_files.iter().map(|path| expand_tilde(path)));
+    }
+    if paths.is_empty() {
+        paths.extend(default_identity_paths());
+    }
+    for path in paths {
+        match native::load_native_identity(&path).and_then(|identity| {
+            sign_user_auth_with_private_key(
+                &identity,
+                hello,
+                server_hello,
+                requested_forwardings.clone(),
+            )
+        }) {
+            Ok(auth) => return Ok(auth),
+            Err(err) => errors.push(format!("{}: {err:#}", path.display())),
+        }
+    }
+    let _ = host_config;
+    Err(anyhow!(
+        "native auth found no usable identity: {}",
+        errors.join("; ")
+    ))
+}
+
+fn default_identity_paths() -> Vec<PathBuf> {
+    ["~/.ssh/id_ed25519", "~/.ssh/id_ecdsa", "~/.ssh/id_rsa"]
+        .into_iter()
+        .map(expand_tilde)
+        .collect()
+}
+
+fn resolve_addr(host: &str, port: u16) -> Result<SocketAddr> {
+    (host, port)
+        .to_socket_addrs()
+        .with_context(|| format!("resolve UDP target {host}:{port}"))?
+        .next()
+        .ok_or_else(|| anyhow!("no UDP address resolved for {host}:{port}"))
+}
+
+fn destination_host(destination: &str) -> String {
+    destination
+        .rsplit('@')
+        .next()
+        .unwrap_or(destination)
+        .split(':')
+        .next()
+        .unwrap_or(destination)
+        .to_string()
+}
+
+fn user_from_destination(destination: &str) -> Option<String> {
+    destination
+        .rsplit_once('@')
+        .map(|(user, _)| user.to_string())
+        .filter(|user| !user.is_empty())
+}
+
+fn default_sdk_session() -> String {
+    let millis = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_millis();
+    format!("sdk-{millis}-{}", std::process::id())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_user_and_host_from_destination() {
+        assert_eq!(
+            user_from_destination("palav@example.com").as_deref(),
+            Some("palav")
+        );
+        assert_eq!(destination_host("palav@example.com"), "example.com");
+        assert_eq!(destination_host("example.com:2222"), "example.com");
+    }
+
+    #[test]
+    fn default_identity_paths_are_expanded() {
+        assert!(
+            default_identity_paths()
+                .iter()
+                .any(|path| path.ends_with(".ssh/id_ed25519"))
+        );
+    }
+}

src/config.rs

@@ -46,6 +46,10 @@ pub struct ServerConfig {
     pub allow_remote_non_loopback_bind: bool,
     #[serde(default)]
     pub allow_agent_forwarding: bool,
+    #[serde(default = "default_true")]
+    pub allow_file_transfer: bool,
+    #[serde(default = "default_true")]
+    pub allow_exec_command: bool,
     #[serde(default = "default_accept_env")]
     pub accept_env: Vec<String>,
     /// Run terminal sessions under per-session holder processes so shells
@@ -82,6 +86,8 @@ impl Default for ServerConfig {
             allow_remote_forwarding: false,
             allow_remote_non_loopback_bind: false,
             allow_agent_forwarding: false,
+            allow_file_transfer: true,
+            allow_exec_command: true,
             accept_env: default_accept_env(),
             persist_sessions: true,
         }
@@ -144,6 +150,12 @@ pub struct ClientConfig {
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct HostConfig {
     pub ssh: Option<String>,
+    /// Optional OpenSSH config host name to use for SSH-backed bootstrap,
+    /// trust/setup/doctor checks, and native-auth identity selection. This lets
+    /// a Dosh host keep a separate UDP endpoint while still inheriting
+    /// alias-scoped OpenSSH settings like IdentityFile, ProxyJump, and SendEnv.
+    #[serde(default)]
+    pub ssh_config: Option<String>,
     pub user: Option<String>,
     pub dosh_host: Option<String>,
     pub port: Option<u16>,

src/exec_service.rs

@@ -0,0 +1,71 @@
+use anyhow::{Context, Result, bail};
+use serde::{Deserialize, Serialize};
+
+pub const EXEC_STREAM_SENTINEL: &str = "@dosh-exec";
+pub const FRAME_MAX_LEN: usize = 1024 * 1024;
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ExecRequest {
+    pub command: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub enum ExecResponse {
+    Stdout(Vec<u8>),
+    Stderr(Vec<u8>),
+    Exit { code: Option<i32> },
+    Error { message: String },
+}
+
+#[derive(Default)]
+pub struct FrameDecoder {
+    buf: Vec<u8>,
+}
+
+impl FrameDecoder {
+    pub fn push(&mut self, bytes: &[u8]) -> Result<Vec<Vec<u8>>> {
+        self.buf.extend_from_slice(bytes);
+        let mut frames = Vec::new();
+        loop {
+            if self.buf.len() < 4 {
+                break;
+            }
+            let len = u32::from_be_bytes(self.buf[..4].try_into().unwrap()) as usize;
+            if len > FRAME_MAX_LEN {
+                bail!("exec protocol frame too large: {len} bytes");
+            }
+            if self.buf.len() < 4 + len {
+                break;
+            }
+            frames.push(self.buf[4..4 + len].to_vec());
+            self.buf.drain(..4 + len);
+        }
+        Ok(frames)
+    }
+}
+
+pub fn encode_request(request: &ExecRequest) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(request).context("encode exec request")?)
+}
+
+pub fn encode_response(response: &ExecResponse) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(response).context("encode exec response")?)
+}
+
+pub fn decode_request(frame: &[u8]) -> Result<ExecRequest> {
+    bincode::deserialize(frame).context("decode exec request")
+}
+
+pub fn decode_response(frame: &[u8]) -> Result<ExecResponse> {
+    bincode::deserialize(frame).context("decode exec response")
+}
+
+fn encode_frame(payload: &[u8]) -> Result<Vec<u8>> {
+    if payload.len() > FRAME_MAX_LEN {
+        bail!("exec protocol frame too large: {} bytes", payload.len());
+    }
+    let mut out = Vec::with_capacity(4 + payload.len());
+    out.extend_from_slice(&(payload.len() as u32).to_be_bytes());
+    out.extend_from_slice(payload);
+    Ok(out)
+}

src/file_transfer.rs

@@ -0,0 +1,280 @@
+use anyhow::{Context, Result, anyhow, bail};
+use serde::{Deserialize, Serialize};
+use std::path::{Path, PathBuf};
+
+pub const FILE_STREAM_SENTINEL: &str = "@dosh-file";
+pub const FRAME_MAX_LEN: usize = 1024 * 1024;
+pub const CHUNK_SIZE: usize = 32 * 1024;
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub enum FileRequest {
+    Stat {
+        path: String,
+    },
+    List {
+        path: String,
+    },
+    Mkdir {
+        path: String,
+        mode: Option<u32>,
+    },
+    Readlink {
+        path: String,
+    },
+    Symlink {
+        path: String,
+        target: String,
+        overwrite: bool,
+    },
+    Remove {
+        path: String,
+        recursive: bool,
+    },
+    PutStart {
+        path: String,
+        size: u64,
+        mode: Option<u32>,
+        modified_secs: Option<u64>,
+        overwrite: bool,
+        resume: bool,
+    },
+    PutChunk {
+        offset: u64,
+        bytes: Vec<u8>,
+    },
+    PutFinish {
+        sha256: [u8; 32],
+    },
+    Get {
+        path: String,
+        offset: u64,
+    },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub enum FileResponse {
+    Ok,
+    Resume {
+        offset: u64,
+        prefix_sha256: Option<[u8; 32]>,
+    },
+    Stat {
+        meta: FileMeta,
+    },
+    List {
+        entries: Vec<FileEntry>,
+    },
+    LinkTarget {
+        target: String,
+    },
+    Start {
+        meta: FileMeta,
+        offset: u64,
+        prefix_sha256: Option<[u8; 32]>,
+    },
+    Chunk {
+        offset: u64,
+        bytes: Vec<u8>,
+    },
+    Done {
+        sha256: [u8; 32],
+        bytes: u64,
+    },
+    Error {
+        message: String,
+    },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct FileMeta {
+    pub path: String,
+    pub kind: FileKind,
+    pub len: u64,
+    pub mode: Option<u32>,
+    pub modified_secs: Option<u64>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+pub enum FileKind {
+    File,
+    Directory,
+    Symlink,
+    Other,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct FileEntry {
+    pub name: String,
+    pub meta: FileMeta,
+}
+
+#[derive(Default)]
+pub struct FrameDecoder {
+    buf: Vec<u8>,
+}
+
+impl FrameDecoder {
+    pub fn push(&mut self, bytes: &[u8]) -> Result<Vec<Vec<u8>>> {
+        self.buf.extend_from_slice(bytes);
+        let mut frames = Vec::new();
+        loop {
+            if self.buf.len() < 4 {
+                break;
+            }
+            let len = u32::from_be_bytes(self.buf[..4].try_into().unwrap()) as usize;
+            if len > FRAME_MAX_LEN {
+                bail!("file protocol frame too large: {len} bytes");
+            }
+            if self.buf.len() < 4 + len {
+                break;
+            }
+            frames.push(self.buf[4..4 + len].to_vec());
+            self.buf.drain(..4 + len);
+        }
+        Ok(frames)
+    }
+}
+
+pub fn encode_request(request: &FileRequest) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(request).context("encode file request")?)
+}
+
+pub fn encode_response(response: &FileResponse) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(response).context("encode file response")?)
+}
+
+pub fn decode_request(frame: &[u8]) -> Result<FileRequest> {
+    bincode::deserialize(frame).context("decode file request")
+}
+
+pub fn decode_response(frame: &[u8]) -> Result<FileResponse> {
+    bincode::deserialize(frame).context("decode file response")
+}
+
+pub fn encode_frame(payload: &[u8]) -> Result<Vec<u8>> {
+    if payload.len() > FRAME_MAX_LEN {
+        bail!("file protocol frame too large: {} bytes", payload.len());
+    }
+    let mut out = Vec::with_capacity(4 + payload.len());
+    out.extend_from_slice(&(payload.len() as u32).to_be_bytes());
+    out.extend_from_slice(payload);
+    Ok(out)
+}
+
+pub fn parse_copy_endpoint(raw: &str) -> CopyEndpoint {
+    if looks_like_windows_path(raw) {
+        return CopyEndpoint::Local(PathBuf::from(raw));
+    }
+    let Some(index) = raw.find(':') else {
+        return CopyEndpoint::Local(PathBuf::from(raw));
+    };
+    let host = &raw[..index];
+    let path = &raw[index + 1..];
+    if host.is_empty() || host.contains('/') || host.contains('\\') {
+        return CopyEndpoint::Local(PathBuf::from(raw));
+    }
+    CopyEndpoint::Remote {
+        host: host.to_string(),
+        path: if path.is_empty() {
+            ".".to_string()
+        } else {
+            path.to_string()
+        },
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum CopyEndpoint {
+    Local(PathBuf),
+    Remote { host: String, path: String },
+}
+
+pub fn remote_join(parent: &str, child: &str) -> String {
+    if parent.is_empty() || parent == "." {
+        return child.to_string();
+    }
+    format!("{}/{}", parent.trim_end_matches('/'), child)
+}
+
+pub fn remote_basename(path: &str) -> String {
+    path.trim_end_matches('/')
+        .rsplit('/')
+        .next()
+        .filter(|value| !value.is_empty())
+        .unwrap_or(path)
+        .to_string()
+}
+
+pub fn clean_remote_path(path: &str, home: &Path) -> Result<PathBuf> {
+    if path.as_bytes().contains(&0) {
+        bail!("remote path contains NUL");
+    }
+    let expanded = if path == "~" {
+        home.to_path_buf()
+    } else if let Some(rest) = path.strip_prefix("~/") {
+        home.join(rest)
+    } else {
+        let raw = Path::new(path);
+        if raw.is_absolute() {
+            raw.to_path_buf()
+        } else {
+            home.join(raw)
+        }
+    };
+    Ok(expanded)
+}
+
+pub fn ensure_relative_child(path: &Path) -> Result<String> {
+    let name = path
+        .file_name()
+        .and_then(|name| name.to_str())
+        .ok_or_else(|| anyhow!("path has no final component: {}", path.display()))?;
+    if name.is_empty() || name == "." || name == ".." {
+        bail!("invalid path final component: {}", path.display());
+    }
+    Ok(name.to_string())
+}
+
+fn looks_like_windows_path(raw: &str) -> bool {
+    let bytes = raw.as_bytes();
+    bytes.len() >= 3
+        && bytes[0].is_ascii_alphabetic()
+        && bytes[1] == b':'
+        && (bytes[2] == b'\\' || bytes[2] == b'/')
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn frames_round_trip_incrementally() {
+        let first = encode_response(&FileResponse::Ok).unwrap();
+        let second = encode_response(&FileResponse::Error {
+            message: "nope".to_string(),
+        })
+        .unwrap();
+        let mut decoder = FrameDecoder::default();
+        assert!(decoder.push(&first[..2]).unwrap().is_empty());
+        let frames = decoder.push(&first[2..]).unwrap();
+        assert_eq!(frames.len(), 1);
+        assert_eq!(decode_response(&frames[0]).unwrap(), FileResponse::Ok);
+        let frames = decoder.push(&second).unwrap();
+        assert_eq!(frames.len(), 1);
+    }
+
+    #[test]
+    fn copy_endpoint_parses_scp_style_but_not_windows_drive() {
+        assert_eq!(
+            parse_copy_endpoint("palav:tmp/file"),
+            CopyEndpoint::Remote {
+                host: "palav".to_string(),
+                path: "tmp/file".to_string()
+            }
+        );
+        assert_eq!(
+            parse_copy_endpoint("C:\\Users\\palav\\x"),
+            CopyEndpoint::Local(PathBuf::from("C:\\Users\\palav\\x"))
+        );
+    }
+}

src/lib.rs

@@ -1,11 +1,27 @@
+//! Dosh is an encrypted UDP transport for remote terminals and embeddable Rust
+//! application streams.
+//!
+//! Use [`client::DoshClient`] and [`server::DoshServer`] when you want Dosh to
+//! handle native authentication, host key checks, roaming, keepalives, reliable
+//! streams, and service routing. Use [`transport::DoshTransport`] only when an
+//! application already owns session establishment and wants direct access to the
+//! encrypted stream transport.
+
 pub mod auth;
 pub mod build_info;
+pub mod client;
 pub mod config;
 pub mod crypto;
+pub mod exec_service;
+pub mod file_transfer;
 pub mod native;
 #[cfg(unix)]
 pub mod persist;
 pub mod protocol;
 #[cfg(unix)]
 pub mod pty;
+pub mod server;
 pub mod ssh_agent;
+pub mod trace;
+pub mod transport;
+pub mod udp;

src/persist.rs

@@ -23,12 +23,14 @@ use std::io::{Read, Write};
 use std::os::fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
 use std::os::unix::net::{UnixListener, UnixStream};
 use std::path::{Path, PathBuf};
+use std::sync::Mutex;
 use std::time::Duration;
 
 /// One-byte commands a server sends to a holder over its control socket after
 /// the holder has handed back the master fd.
 const HOLDER_CMD_SHUTDOWN: u8 = b'X';
 const HOLDER_STARTUP_TIMEOUT: Duration = Duration::from_millis(750);
+static SCREEN_WRITE_LOCK: Mutex<()> = Mutex::new(());
 
 /// Magic written into a holder's `meta` file, bumped if the on-disk layout
 /// changes so a stale holder from an incompatible build is ignored.
@@ -140,13 +142,28 @@ pub fn save_screen(
         // No holder runtime for this session (non-persistent): nothing to do.
         return Ok(());
     }
+    let _guard = SCREEN_WRITE_LOCK
+        .lock()
+        .map_err(|_| anyhow!("screen persistence lock poisoned"))?;
+    let path = screen_path(&dir);
+    if existing_screen_output_seq(&path).is_some_and(|existing| existing >= output_seq) {
+        return Ok(());
+    }
     let mut buf = Vec::with_capacity(snapshot.len() + 32);
     buf.extend_from_slice(&cols.to_be_bytes());
     buf.extend_from_slice(&rows.to_be_bytes());
     buf.extend_from_slice(&output_seq.to_be_bytes());
     buf.extend_from_slice(&(snapshot.len() as u32).to_be_bytes());
     buf.extend_from_slice(snapshot);
-    atomic_write(&screen_path(&dir), &buf)
+    atomic_write(&path, &buf)
+}
+
+fn existing_screen_output_seq(path: &Path) -> Option<u64> {
+    let data = std::fs::read(path).ok()?;
+    if data.len() < 12 {
+        return None;
+    }
+    Some(u64::from_be_bytes(data[4..12].try_into().ok()?))
 }
 
 /// A restored screen for a re-adopted session.
@@ -435,6 +452,10 @@ pub fn run_holder(
         let mut cmd = [0u8; 1];
         match stream.read(&mut cmd) {
             Ok(1) if cmd[0] == HOLDER_CMD_SHUTDOWN => {
+                if shell_pid > 0 {
+                    let _ = unsafe { libc::kill(shell_pid, libc::SIGHUP) };
+                    let _ = unsafe { libc::kill(shell_pid, libc::SIGTERM) };
+                }
                 let _ = std::fs::remove_dir_all(runtime_dir);
                 std::process::exit(0);
             }
@@ -615,6 +636,20 @@ mod tests {
         assert_eq!(loaded.snapshot, snap);
     }
 
+    #[test]
+    fn save_screen_never_overwrites_newer_snapshot_with_older_seq() {
+        let tmp = tempfile::tempdir().unwrap();
+        let sessions_dir = tmp.path();
+        ensure_runtime_dir(sessions_dir, "work").unwrap();
+
+        save_screen(sessions_dir, "work", 80, 24, 10, b"new-screen").unwrap();
+        save_screen(sessions_dir, "work", 80, 24, 9, b"old-screen").unwrap();
+
+        let loaded = load_screen(sessions_dir, "work").expect("screen restored");
+        assert_eq!(loaded.output_seq, 10);
+        assert_eq!(loaded.snapshot, b"new-screen");
+    }
+
     #[test]
     fn load_screen_absent_is_none() {
         let tmp = tempfile::tempdir().unwrap();

src/protocol.rs

@@ -280,7 +280,7 @@ pub fn decode(input: &[u8]) -> Result<Packet> {
 
 pub fn decrypt_body(packet: &Packet, key: &[u8; 32], direction: u32) -> Result<Vec<u8>> {
     if packet.header.flags & 1 == 0 {
-        return Ok(packet.body.clone());
+        bail!("packet body is not encrypted");
     }
     let nonce = crypto::nonce_from(direction, packet.header.seq);
     let aad = packet.header.aad();
@@ -357,6 +357,10 @@ pub struct NativeAuthCheckOkBody {
     pub allow_tcp_forwarding: bool,
     pub allow_remote_forwarding: bool,
     pub allow_agent_forwarding: bool,
+    #[serde(default)]
+    pub allow_file_transfer: bool,
+    #[serde(default)]
+    pub allow_exec_command: bool,
     pub policy_flags: Vec<String>,
     #[serde(default)]
     pub server_version: String,

src/server.rs

@@ -0,0 +1,709 @@
+use crate::config::{ServerConfig, load_server_config};
+use crate::crypto;
+use crate::native::{
+    self, ForwardingKind, ForwardingRequest, NativeAuthOk, NativeServerHello,
+    derive_native_session_key, generate_native_ephemeral, host_public_key, load_or_create_host_key,
+    sign_server_hello, verify_native_user_auth_from_config,
+};
+use crate::protocol::{
+    self, AttachReject, CLIENT_TO_SERVER, NativeAuthOkBody, NativeClientHelloBody,
+    NativeServerHelloBody, NativeUserAuthBody, PacketKind, SERVER_TO_CLIENT,
+};
+use crate::transport::{
+    DoshTransport, SessionEvent, SessionRole, SessionTransportConfig, TransportConfig,
+    service_name_from_target,
+};
+use crate::udp::{is_transient_udp_error, is_transient_udp_send_error};
+use anyhow::{Context, Result, anyhow, bail};
+use ed25519_dalek::SigningKey;
+use std::collections::{HashMap, HashSet};
+use std::net::SocketAddr;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+use tokio::net::UdpSocket;
+
+#[derive(Debug, Clone)]
+pub struct DoshServerConfig {
+    pub server: ServerConfig,
+    pub bind_addr: Option<SocketAddr>,
+    pub services: HashSet<String>,
+    pub transport: TransportConfig,
+    pub require_current_user: bool,
+    pub auth_timeout: Duration,
+}
+
+impl DoshServerConfig {
+    pub fn new(server: ServerConfig) -> Self {
+        Self {
+            server,
+            bind_addr: None,
+            services: HashSet::new(),
+            transport: TransportConfig::default(),
+            require_current_user: true,
+            auth_timeout: Duration::from_secs(30),
+        }
+    }
+
+    pub fn bind_addr(mut self, addr: SocketAddr) -> Self {
+        self.bind_addr = Some(addr);
+        self
+    }
+
+    pub fn service(mut self, name: impl Into<String>) -> Result<Self> {
+        self.services.insert(validate_service_name(name.into())?);
+        Ok(self)
+    }
+
+    pub fn services(mut self, names: impl IntoIterator<Item = impl Into<String>>) -> Result<Self> {
+        for name in names {
+            self.services.insert(validate_service_name(name.into())?);
+        }
+        Ok(self)
+    }
+
+    pub fn require_current_user(mut self, value: bool) -> Self {
+        self.require_current_user = value;
+        self
+    }
+
+    pub fn transport(mut self, transport: TransportConfig) -> Self {
+        self.transport = transport;
+        self
+    }
+}
+
+impl Default for DoshServerConfig {
+    fn default() -> Self {
+        Self::new(ServerConfig::default())
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct DoshAccepted {
+    pub conn_id: [u8; 16],
+    pub user: String,
+    pub session: String,
+    pub services: Vec<String>,
+    pub peer_addr: SocketAddr,
+}
+
+#[derive(Debug, Clone)]
+pub enum DoshServerEvent {
+    Accepted(DoshAccepted),
+    Session {
+        conn_id: [u8; 16],
+        event: SessionEvent,
+    },
+    Ignored,
+}
+
+#[derive(Debug, Clone)]
+struct PendingServerAuth {
+    client: native::NativeClientHello,
+    server: NativeServerHello,
+    session_key: [u8; 32],
+    peer: SocketAddr,
+    created_at: Instant,
+}
+
+pub struct DoshServer {
+    socket: Arc<UdpSocket>,
+    config: DoshServerConfig,
+    host_signing: SigningKey,
+    pending: HashMap<[u8; 16], PendingServerAuth>,
+    transports: HashMap<[u8; 16], DoshTransport>,
+    accepted: HashMap<[u8; 16], DoshAccepted>,
+}
+
+impl DoshServer {
+    pub async fn load() -> Result<Self> {
+        Self::bind(DoshServerConfig::new(load_server_config(None)?)).await
+    }
+
+    pub async fn load_from_path(path: Option<PathBuf>) -> Result<Self> {
+        Self::bind(DoshServerConfig::new(load_server_config(path)?)).await
+    }
+
+    pub async fn bind(config: DoshServerConfig) -> Result<Self> {
+        let bind_addr = match config.bind_addr {
+            Some(addr) => addr,
+            None => format!("{}:{}", config.server.bind, config.server.port)
+                .parse()
+                .with_context(|| {
+                    format!(
+                        "parse Dosh bind address {}:{}",
+                        config.server.bind, config.server.port
+                    )
+                })?,
+        };
+        let host_signing = load_or_create_host_key(&config.server)?;
+        let socket = Arc::new(UdpSocket::bind(bind_addr).await?);
+        Ok(Self {
+            socket,
+            config,
+            host_signing,
+            pending: HashMap::new(),
+            transports: HashMap::new(),
+            accepted: HashMap::new(),
+        })
+    }
+
+    pub fn local_addr(&self) -> Result<SocketAddr> {
+        Ok(self.socket.local_addr()?)
+    }
+
+    pub fn connection(&self, conn_id: &[u8; 16]) -> Option<&DoshAccepted> {
+        self.accepted.get(conn_id)
+    }
+
+    pub fn transport(&self, conn_id: &[u8; 16]) -> Option<&DoshTransport> {
+        self.transports.get(conn_id)
+    }
+
+    pub fn transport_mut(&mut self, conn_id: &[u8; 16]) -> Option<&mut DoshTransport> {
+        self.transports.get_mut(conn_id)
+    }
+
+    pub async fn recv(&mut self) -> Result<DoshServerEvent> {
+        let mut buf = vec![0u8; 65535];
+        loop {
+            self.expire_pending();
+            let (n, peer) = match self.socket.recv_from(&mut buf).await {
+                Ok(value) => value,
+                Err(err) if is_transient_udp_error(&err) => continue,
+                Err(err) => return Err(err.into()),
+            };
+            let packet = match protocol::decode(&buf[..n]) {
+                Ok(packet) => packet,
+                Err(_) => continue,
+            };
+            if packet.header.kind == PacketKind::NativeClientHello {
+                self.handle_client_hello(peer, packet.body).await?;
+                return Ok(DoshServerEvent::Ignored);
+            }
+            if packet.header.kind == PacketKind::NativeUserAuth {
+                return self.handle_user_auth(peer, &packet).await;
+            }
+            if let Some(transport) = self.transports.get_mut(&packet.header.conn_id) {
+                let event = transport.handle_datagram(&buf[..n], peer).await?;
+                return Ok(DoshServerEvent::Session {
+                    conn_id: packet.header.conn_id,
+                    event,
+                });
+            }
+            self.send_reject(peer, packet.header.conn_id, "unknown Dosh connection")
+                .await?;
+            return Ok(DoshServerEvent::Ignored);
+        }
+    }
+
+    pub async fn accept_stream(&mut self, conn_id: [u8; 16], stream_id: u64) -> Result<()> {
+        self.transport_mut(&conn_id)
+            .ok_or_else(|| anyhow!("unknown Dosh connection"))?
+            .accept_stream(stream_id)
+            .await
+    }
+
+    pub async fn reject_stream(
+        &mut self,
+        conn_id: [u8; 16],
+        stream_id: u64,
+        reason: impl Into<String>,
+    ) -> Result<()> {
+        self.transport_mut(&conn_id)
+            .ok_or_else(|| anyhow!("unknown Dosh connection"))?
+            .reject_stream(stream_id, reason)
+            .await
+    }
+
+    pub async fn send(
+        &mut self,
+        conn_id: [u8; 16],
+        stream_id: u64,
+        bytes: impl Into<Vec<u8>>,
+    ) -> Result<()> {
+        self.transport_mut(&conn_id)
+            .ok_or_else(|| anyhow!("unknown Dosh connection"))?
+            .send(stream_id, bytes)
+            .await
+    }
+
+    pub async fn close(&mut self, conn_id: [u8; 16], stream_id: u64) -> Result<()> {
+        self.transport_mut(&conn_id)
+            .ok_or_else(|| anyhow!("unknown Dosh connection"))?
+            .close(stream_id)
+            .await
+    }
+
+    pub async fn maintenance(&mut self) -> Result<()> {
+        for transport in self.transports.values_mut() {
+            transport.maintenance().await?;
+        }
+        Ok(())
+    }
+
+    async fn handle_client_hello(&mut self, peer: SocketAddr, body: Vec<u8>) -> Result<()> {
+        let req: NativeClientHelloBody = protocol::from_body(&body)?;
+        if let Err(err) =
+            native::check_native_protocol_version(req.hello.protocol_version, "client")
+        {
+            self.send_reject(peer, [0u8; 16], &err.to_string()).await?;
+            return Ok(());
+        }
+        let result = self.build_server_hello(req.hello, peer);
+        let (pending_id, hello) = match result {
+            Ok(value) => value,
+            Err(err) => {
+                self.send_reject(peer, [0u8; 16], &err.to_string()).await?;
+                return Ok(());
+            }
+        };
+        let body = protocol::to_body(&NativeServerHelloBody { hello })?;
+        let out = protocol::encode_plain(PacketKind::NativeServerHello, pending_id, 1, 0, &body)?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
+        Ok(())
+    }
+
+    fn build_server_hello(
+        &mut self,
+        client: native::NativeClientHello,
+        peer: SocketAddr,
+    ) -> Result<([u8; 16], NativeServerHello)> {
+        if !self.config.server.native_auth {
+            bail!("native auth disabled");
+        }
+        if !client
+            .supported_aead
+            .iter()
+            .any(|algorithm| algorithm == "chacha20poly1305")
+        {
+            bail!("native auth requires chacha20poly1305");
+        }
+        if !client
+            .supported_user_key_algorithms
+            .iter()
+            .any(|algorithm| native::is_supported_user_signature_algorithm(algorithm))
+        {
+            bail!("native auth requires a supported user key algorithm");
+        }
+        if self.config.require_current_user {
+            let current_user = std::env::var("USER").unwrap_or_else(|_| "unknown".to_string());
+            if client.requested_user != current_user {
+                bail!("native auth user mismatch");
+            }
+        }
+
+        let (server_secret, server_public) = generate_native_ephemeral();
+        let mut server = NativeServerHello {
+            protocol_version: native::NATIVE_PROTOCOL_VERSION,
+            server_random: crypto::random_32(),
+            server_ephemeral_public: server_public,
+            host_key: host_public_key(&self.host_signing),
+            chosen_aead: "chacha20poly1305".to_string(),
+            server_key_epoch: 1,
+            auth_challenge: crypto::random_32(),
+            rate_limit_remaining: None,
+            host_signature: Vec::new(),
+        };
+        sign_server_hello(&self.host_signing, &client, &mut server)?;
+        let session_key = derive_native_session_key(
+            &server_secret,
+            client.client_ephemeral_public,
+            &client,
+            &server,
+        )?;
+        let mut pending_id = [0u8; 16];
+        pending_id.copy_from_slice(&server.auth_challenge[..16]);
+        self.pending.insert(
+            pending_id,
+            PendingServerAuth {
+                client,
+                server: server.clone(),
+                session_key,
+                peer,
+                created_at: Instant::now(),
+            },
+        );
+        Ok((pending_id, server))
+    }
+
+    async fn handle_user_auth(
+        &mut self,
+        peer: SocketAddr,
+        packet: &protocol::Packet,
+    ) -> Result<DoshServerEvent> {
+        let Some(pending) = self.pending.get(&packet.header.conn_id).cloned() else {
+            self.send_reject(peer, packet.header.conn_id, "unknown native auth")
+                .await?;
+            return Ok(DoshServerEvent::Ignored);
+        };
+        if pending.peer != peer {
+            self.send_reject(peer, packet.header.conn_id, "native auth peer changed")
+                .await?;
+            return Ok(DoshServerEvent::Ignored);
+        }
+        if pending.created_at.elapsed() > self.config.auth_timeout {
+            self.pending.remove(&packet.header.conn_id);
+            self.send_reject(peer, packet.header.conn_id, "native auth expired")
+                .await?;
+            return Ok(DoshServerEvent::Ignored);
+        }
+
+        let body = match protocol::decrypt_body(packet, &pending.session_key, CLIENT_TO_SERVER) {
+            Ok(body) => body,
+            Err(_) => {
+                self.send_reject(peer, packet.header.conn_id, "native auth decrypt failed")
+                    .await?;
+                return Ok(DoshServerEvent::Ignored);
+            }
+        };
+        let req: NativeUserAuthBody = match protocol::from_body(&body) {
+            Ok(req) => req,
+            Err(_) => {
+                self.send_reject(peer, packet.header.conn_id, "invalid native auth body")
+                    .await?;
+                return Ok(DoshServerEvent::Ignored);
+            }
+        };
+        let services = match self.verify_auth_and_services(&pending, &req.auth) {
+            Ok(services) => services,
+            Err(err) => {
+                self.send_reject(peer, packet.header.conn_id, &format!("{err:#}"))
+                    .await?;
+                return Ok(DoshServerEvent::Ignored);
+            }
+        };
+        self.pending.remove(&packet.header.conn_id);
+
+        let conn_id = crypto::random_16();
+        let key_id = protocol::session_key_id(&pending.session_key);
+        let ok = NativeAuthOk {
+            client_id: conn_id,
+            session: pending.client.requested_session.clone(),
+            mode: pending.client.requested_mode.clone(),
+            session_key: pending.session_key,
+            session_key_id: key_id,
+            attach_ticket: Vec::new(),
+            attach_ticket_psk: crypto::random_32(),
+            initial_seq: 1,
+            snapshot: Vec::new(),
+            policy_flags: services
+                .iter()
+                .map(|service| format!("service:{service}"))
+                .collect(),
+        };
+        let body = protocol::to_body(&NativeAuthOkBody { ok })?;
+        let out = protocol::encode_encrypted(
+            PacketKind::NativeAuthOk,
+            conn_id,
+            1,
+            packet.header.seq,
+            &pending.session_key,
+            SERVER_TO_CLIENT,
+            &body,
+        )?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
+
+        let transport = DoshTransport::new(
+            Arc::clone(&self.socket),
+            SessionTransportConfig {
+                role: SessionRole::Server,
+                conn_id,
+                session_key: pending.session_key,
+                peer_addr: peer,
+                initial_send_seq: 2,
+                initial_ack: packet.header.seq,
+                stream: self.config.transport.clone(),
+            },
+        );
+        let accepted = DoshAccepted {
+            conn_id,
+            user: pending.client.requested_user,
+            session: pending.client.requested_session,
+            services,
+            peer_addr: peer,
+        };
+        self.transports.insert(conn_id, transport);
+        self.accepted.insert(conn_id, accepted.clone());
+        Ok(DoshServerEvent::Accepted(accepted))
+    }
+
+    fn verify_auth_and_services(
+        &self,
+        pending: &PendingServerAuth,
+        auth: &native::NativeUserAuth,
+    ) -> Result<Vec<String>> {
+        verify_native_user_auth_from_config(
+            &self.config.server,
+            &pending.client,
+            &pending.server,
+            auth,
+            Some(pending.peer.ip()),
+        )
+        .context("verify native user auth")?;
+        validate_requested_services(&self.config.services, &auth.requested_forwardings)
+    }
+
+    async fn send_reject(&self, peer: SocketAddr, conn_id: [u8; 16], reason: &str) -> Result<()> {
+        let body = protocol::to_body(&AttachReject {
+            reason: reason.to_string(),
+        })?;
+        let out = protocol::encode_plain(PacketKind::AttachReject, conn_id, 0, 0, &body)?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
+        Ok(())
+    }
+
+    fn expire_pending(&mut self) {
+        let timeout = self.config.auth_timeout;
+        self.pending
+            .retain(|_, pending| pending.created_at.elapsed() <= timeout);
+    }
+}
+
+async fn send_udp(socket: &UdpSocket, packet: &[u8], peer: SocketAddr) -> Result<bool> {
+    match socket.send_to(packet, peer).await {
+        Ok(_) => Ok(true),
+        Err(err) if is_transient_udp_send_error(&err) => Ok(false),
+        Err(err) => Err(err).with_context(|| format!("send UDP packet to {peer}")),
+    }
+}
+
+fn validate_requested_services(
+    allowed_services: &HashSet<String>,
+    requests: &[ForwardingRequest],
+) -> Result<Vec<String>> {
+    let mut services = Vec::new();
+    for request in requests {
+        if request.kind != ForwardingKind::Local {
+            bail!("embedded Dosh services only accept local service requests");
+        }
+        if request.listen_port != 0 || request.target_port != Some(0) {
+            bail!("embedded Dosh service requests must use port 0");
+        }
+        let target = request
+            .target_host
+            .as_deref()
+            .ok_or_else(|| anyhow!("embedded Dosh service request is missing target host"))?;
+        let service = service_name_from_target(target)
+            .ok_or_else(|| anyhow!("target {target:?} is not a Dosh service"))?;
+        if !allowed_services.contains(service) {
+            bail!("Dosh service {service:?} is not registered");
+        }
+        if !services.iter().any(|existing| existing == service) {
+            services.push(service.to_string());
+        }
+    }
+    Ok(services)
+}
+
+fn validate_service_name(name: String) -> Result<String> {
+    crate::transport::service_target(&name)?;
+    Ok(name)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::client::DoshClient;
+    use crate::config::{ClientConfig, HostsConfig};
+    use crate::protocol::{CLIENT_TO_SERVER, NativeUserAuthBody};
+    use crate::transport::TransportEvent;
+    use ed25519_dalek::SigningKey;
+
+    #[tokio::test]
+    async fn sdk_client_and_server_exchange_service_stream() {
+        let dir = tempfile::tempdir().unwrap();
+        let host_key = dir.path().join("host_key");
+        let authorized_keys = dir.path().join("authorized_keys");
+        let identity = dir.path().join("id_ed25519");
+        let known_hosts = dir.path().join("known_hosts");
+
+        let signing = SigningKey::from_bytes(&[91u8; 32]);
+        let keypair = ssh_key::private::Ed25519Keypair::from(&signing);
+        let private =
+            ssh_key::PrivateKey::new(ssh_key::private::KeypairData::from(keypair), "").unwrap();
+        private
+            .write_openssh_file(&identity, ssh_key::LineEnding::LF)
+            .unwrap();
+        std::fs::write(
+            &authorized_keys,
+            format!("{}\n", private.public_key().to_openssh().unwrap()),
+        )
+        .unwrap();
+
+        let server_config = ServerConfig {
+            host_key: host_key.to_string_lossy().to_string(),
+            authorized_keys: vec![authorized_keys.to_string_lossy().to_string()],
+            ..ServerConfig::default()
+        };
+        let server_config = DoshServerConfig::new(server_config)
+            .bind_addr("127.0.0.1:0".parse().unwrap())
+            .service("echo")
+            .unwrap()
+            .require_current_user(false);
+        let mut server = DoshServer::bind(server_config).await.unwrap();
+        let server_port = server.local_addr().unwrap().port();
+
+        let client_config = ClientConfig {
+            dosh_port: server_port,
+            trust_on_first_use: true,
+            known_hosts: known_hosts.to_string_lossy().to_string(),
+            identity_files: vec![identity.to_string_lossy().to_string()],
+            use_ssh_agent: false,
+            ..ClientConfig::default()
+        };
+        let client = DoshClient::with_config(client_config, HostsConfig::default());
+        let connect = client
+            .connect("127.0.0.1")
+            .user("sdk-user")
+            .service("echo")
+            .connect();
+        let accept = async {
+            loop {
+                if let DoshServerEvent::Accepted(accepted) = server.recv().await.unwrap() {
+                    break accepted;
+                }
+            }
+        };
+        let (connected, accepted) = tokio::join!(connect, accept);
+        let mut client_transport = connected.unwrap().into_transport();
+        let conn_id = accepted.conn_id;
+        assert_eq!(accepted.services, vec!["echo".to_string()]);
+
+        let stream_id = client_transport.open_service("echo").await.unwrap();
+        match server.recv().await.unwrap() {
+            DoshServerEvent::Session {
+                event: SessionEvent::Stream(TransportEvent::Open(open)),
+                ..
+            } => {
+                assert_eq!(open.stream_id, stream_id);
+                server.accept_stream(conn_id, open.stream_id).await.unwrap();
+            }
+            other => panic!("unexpected event {other:?}"),
+        }
+        assert!(matches!(
+            client_transport.recv().await.unwrap(),
+            SessionEvent::Stream(TransportEvent::OpenOk { .. })
+        ));
+
+        client_transport
+            .send(stream_id, b"ping".to_vec())
+            .await
+            .unwrap();
+        loop {
+            match server.recv().await.unwrap() {
+                DoshServerEvent::Session {
+                    event: SessionEvent::Stream(TransportEvent::Data(data)),
+                    ..
+                } => {
+                    assert_eq!(data.chunks, vec![b"ping".to_vec()]);
+                    server
+                        .send(conn_id, data.stream_id, b"pong".to_vec())
+                        .await
+                        .unwrap();
+                    break;
+                }
+                DoshServerEvent::Session { .. } | DoshServerEvent::Ignored => {}
+                other => panic!("unexpected event {other:?}"),
+            }
+        }
+        loop {
+            match client_transport.recv().await.unwrap() {
+                SessionEvent::Stream(TransportEvent::Data(data)) => {
+                    assert_eq!(data.chunks, vec![b"pong".to_vec()]);
+                    break;
+                }
+                SessionEvent::Stream(_) | SessionEvent::Ignored => {}
+                other => panic!("unexpected event {other:?}"),
+            }
+        }
+    }
+
+    #[tokio::test]
+    async fn bad_native_auth_does_not_consume_pending_challenge() {
+        let dir = tempfile::tempdir().unwrap();
+        let host_key = dir.path().join("host_key");
+        let authorized_keys = dir.path().join("authorized_keys");
+        let signing = SigningKey::from_bytes(&[93u8; 32]);
+        let keypair = ssh_key::private::Ed25519Keypair::from(&signing);
+        let private =
+            ssh_key::PrivateKey::new(ssh_key::private::KeypairData::from(keypair), "").unwrap();
+        std::fs::write(
+            &authorized_keys,
+            format!("{}\n", private.public_key().to_openssh().unwrap()),
+        )
+        .unwrap();
+
+        let server_config = ServerConfig {
+            host_key: host_key.to_string_lossy().to_string(),
+            authorized_keys: vec![authorized_keys.to_string_lossy().to_string()],
+            ..ServerConfig::default()
+        };
+        let server_config = DoshServerConfig::new(server_config)
+            .bind_addr("127.0.0.1:0".parse().unwrap())
+            .require_current_user(false);
+        let mut server = DoshServer::bind(server_config).await.unwrap();
+        let peer: SocketAddr = "127.0.0.1:9".parse().unwrap();
+        let (client_secret, client_public) = native::generate_native_ephemeral();
+        let hello = native::NativeClientHello {
+            protocol_version: native::NATIVE_PROTOCOL_VERSION,
+            client_random: crypto::random_32(),
+            client_ephemeral_public: client_public,
+            requested_host: "127.0.0.1".to_string(),
+            requested_user: "sdk-user".to_string(),
+            requested_session: "test".to_string(),
+            requested_mode: "forward-only".to_string(),
+            terminal_size: (80, 24),
+            supported_aead: vec!["chacha20poly1305".to_string()],
+            supported_user_key_algorithms: vec!["ssh-ed25519".to_string()],
+            cached_host_key_fingerprint: None,
+            attach_ticket_envelope: None,
+            requested_env: Vec::new(),
+        };
+        let (pending_id, server_hello) = server.build_server_hello(hello.clone(), peer).unwrap();
+        let session_key = native::derive_native_session_key(
+            &client_secret,
+            server_hello.server_ephemeral_public,
+            &hello,
+            &server_hello,
+        )
+        .unwrap();
+        let auth = native::sign_user_auth(&signing, &hello, &server_hello, Vec::new()).unwrap();
+        let body = protocol::to_body(&NativeUserAuthBody { auth }).unwrap();
+        let bad = protocol::encode_encrypted(
+            PacketKind::NativeUserAuth,
+            pending_id,
+            2,
+            1,
+            &[7u8; 32],
+            CLIENT_TO_SERVER,
+            &body,
+        )
+        .unwrap();
+        let bad = protocol::decode(&bad).unwrap();
+
+        assert!(matches!(
+            server.handle_user_auth(peer, &bad).await.unwrap(),
+            DoshServerEvent::Ignored
+        ));
+        assert!(server.pending.contains_key(&pending_id));
+
+        let valid = protocol::encode_encrypted(
+            PacketKind::NativeUserAuth,
+            pending_id,
+            2,
+            1,
+            &session_key,
+            CLIENT_TO_SERVER,
+            &body,
+        )
+        .unwrap();
+        let valid = protocol::decode(&valid).unwrap();
+        assert!(matches!(
+            server.handle_user_auth(peer, &valid).await.unwrap(),
+            DoshServerEvent::Accepted(_)
+        ));
+        assert!(!server.pending.contains_key(&pending_id));
+    }
+}

src/trace.rs

@@ -0,0 +1,161 @@
+use std::fs::{File, OpenOptions};
+use std::io::Write;
+use std::path::PathBuf;
+use std::sync::{Mutex, OnceLock};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+static TRACE_FILE: OnceLock<Option<Mutex<File>>> = OnceLock::new();
+static TRACE_BYTES: OnceLock<bool> = OnceLock::new();
+
+pub fn enabled() -> bool {
+    TRACE_FILE.get_or_init(open_trace_file).is_some()
+}
+
+pub fn bytes_enabled() -> bool {
+    *TRACE_BYTES.get_or_init(|| truthy_env("DOSH_TRACE_BYTES"))
+}
+
+pub fn event(name: &str, fields: &[(&str, String)]) {
+    let Some(file) = TRACE_FILE.get_or_init(open_trace_file) else {
+        return;
+    };
+    let now = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|duration| duration.as_millis())
+        .unwrap_or(0);
+    let mut line = format!(
+        "ts_ms={} pid={} event={}",
+        now,
+        std::process::id(),
+        shell_escape(name)
+    );
+    for (key, value) in fields {
+        line.push(' ');
+        line.push_str(key);
+        line.push('=');
+        line.push_str(&shell_escape(value));
+    }
+    line.push('\n');
+    if let Ok(mut file) = file.lock() {
+        let _ = file.write_all(line.as_bytes());
+        let _ = file.flush();
+    }
+}
+
+pub fn bytes_summary(bytes: &[u8]) -> String {
+    let mut parts = vec![
+        format!("len={}", bytes.len()),
+        format!(
+            "esc={}",
+            contains_byte(bytes, 0x1b) || contains_byte(bytes, 0x9b)
+        ),
+        format!("focus={}", has_focus_report(bytes)),
+        format!("mouseish={}", looks_mouseish(bytes)),
+        format!("printable={}", printable_count(bytes)),
+    ];
+    if bytes_enabled() {
+        parts.push(format!("hex={}", hex_prefix(bytes, 160)));
+    }
+    parts.join(",")
+}
+
+fn open_trace_file() -> Option<Mutex<File>> {
+    let raw = std::env::var_os("DOSH_TRACE")?;
+    let normalized = raw.to_string_lossy().to_ascii_lowercase();
+    if normalized.is_empty() || matches!(normalized.as_str(), "0" | "false" | "off") {
+        return None;
+    }
+    let path = if matches!(normalized.as_str(), "1" | "true" | "on") {
+        default_trace_path()
+    } else {
+        PathBuf::from(raw)
+    };
+    if let Some(parent) = path.parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+    OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&path)
+        .ok()
+        .map(Mutex::new)
+}
+
+fn default_trace_path() -> PathBuf {
+    let root = dirs::cache_dir()
+        .unwrap_or_else(std::env::temp_dir)
+        .join("dosh")
+        .join("trace");
+    let exe = std::env::current_exe()
+        .ok()
+        .and_then(|path| {
+            path.file_stem()
+                .map(|stem| stem.to_string_lossy().to_string())
+        })
+        .unwrap_or_else(|| "dosh".to_string());
+    root.join(format!("{}-{}.log", exe, std::process::id()))
+}
+
+fn truthy_env(name: &str) -> bool {
+    std::env::var_os(name).is_some_and(|value| {
+        let normalized = value.to_string_lossy().to_ascii_lowercase();
+        !normalized.is_empty() && !matches!(normalized.as_str(), "0" | "false" | "off")
+    })
+}
+
+fn shell_escape(value: &str) -> String {
+    if value.bytes().all(|byte| {
+        byte.is_ascii_alphanumeric()
+            || matches!(byte, b'.' | b'-' | b'_' | b':' | b'/' | b',' | b'=')
+    }) {
+        return value.to_string();
+    }
+    let mut out = String::from("'");
+    for ch in value.chars() {
+        if ch == '\'' {
+            out.push_str("'\\''");
+        } else {
+            out.push(ch);
+        }
+    }
+    out.push('\'');
+    out
+}
+
+fn contains_byte(bytes: &[u8], needle: u8) -> bool {
+    bytes.contains(&needle)
+}
+
+fn has_focus_report(bytes: &[u8]) -> bool {
+    bytes
+        .windows(3)
+        .any(|window| matches!(window, b"\x1b[I" | b"\x1b[O"))
+        || bytes
+            .windows(2)
+            .any(|window| matches!(window, b"\x9bI" | b"\x9bO"))
+}
+
+fn looks_mouseish(bytes: &[u8]) -> bool {
+    bytes.windows(3).any(|window| window == b"\x1b[<")
+        || bytes.windows(2).any(|window| window == b"\x9b<")
+        || bytes.iter().filter(|byte| **byte == b';').take(3).count() >= 2
+}
+
+fn printable_count(bytes: &[u8]) -> usize {
+    bytes
+        .iter()
+        .filter(|byte| byte.is_ascii_graphic() || **byte == b' ')
+        .count()
+}
+
+fn hex_prefix(bytes: &[u8], max: usize) -> String {
+    let mut out = String::with_capacity(bytes.len().min(max) * 2);
+    for byte in bytes.iter().take(max) {
+        use std::fmt::Write as _;
+        let _ = write!(&mut out, "{byte:02x}");
+    }
+    if bytes.len() > max {
+        out.push_str("...");
+    }
+    out
+}

src/udp.rs

@@ -0,0 +1,190 @@
+//! UDP error classification shared by Dosh clients, servers, and embedders.
+
+use std::net::SocketAddr;
+use std::time::{Duration, Instant};
+use tokio::net::UdpSocket;
+
+pub fn is_transient_udp_error(err: &std::io::Error) -> bool {
+    matches!(
+        err.kind(),
+        std::io::ErrorKind::Interrupted
+            | std::io::ErrorKind::TimedOut
+            | std::io::ErrorKind::WouldBlock
+    ) || err.raw_os_error().is_some_and(is_transient_udp_os_error)
+}
+
+pub fn is_transient_udp_send_error(err: &std::io::Error) -> bool {
+    is_transient_udp_error(err)
+}
+
+pub async fn send_udp_retrying_transient(
+    socket: &UdpSocket,
+    packet: &[u8],
+    peer: SocketAddr,
+    wait: Duration,
+) -> std::io::Result<()> {
+    let deadline = Instant::now() + wait.max(Duration::from_millis(1));
+    loop {
+        match socket.send_to(packet, peer).await {
+            Ok(_) => return Ok(()),
+            Err(err) if is_transient_udp_send_error(&err) && Instant::now() < deadline => {
+                sleep_until_retry(deadline).await;
+            }
+            Err(err) => return Err(err),
+        }
+    }
+}
+
+pub async fn recv_udp_retrying_transient(
+    socket: &UdpSocket,
+    buf: &mut [u8],
+    wait: Duration,
+) -> std::io::Result<(usize, SocketAddr)> {
+    let deadline = Instant::now() + wait.max(Duration::from_millis(1));
+    loop {
+        let now = Instant::now();
+        if now >= deadline {
+            return Err(std::io::Error::from(std::io::ErrorKind::TimedOut));
+        }
+        match tokio::time::timeout(deadline - now, socket.recv_from(buf)).await {
+            Ok(Ok(value)) => return Ok(value),
+            Ok(Err(err)) if is_transient_udp_error(&err) && Instant::now() < deadline => {
+                sleep_until_retry(deadline).await;
+            }
+            Ok(Err(err)) => return Err(err),
+            Err(_) => return Err(std::io::Error::from(std::io::ErrorKind::TimedOut)),
+        }
+    }
+}
+
+async fn sleep_until_retry(deadline: Instant) {
+    let now = Instant::now();
+    if now >= deadline {
+        return;
+    }
+    tokio::time::sleep((deadline - now).min(Duration::from_millis(20))).await;
+}
+
+#[cfg(unix)]
+fn is_transient_udp_os_error(code: i32) -> bool {
+    matches!(
+        code,
+        libc::EADDRNOTAVAIL
+            | libc::ECONNREFUSED
+            | libc::ECONNRESET
+            | libc::EHOSTDOWN
+            | libc::EHOSTUNREACH
+            | libc::ENETDOWN
+            | libc::ENETRESET
+            | libc::ENETUNREACH
+            | libc::ETIMEDOUT
+    )
+}
+
+#[cfg(windows)]
+fn is_transient_udp_os_error(code: i32) -> bool {
+    matches!(
+        code,
+        10049  // WSAEADDRNOTAVAIL
+            | 10050 // WSAENETDOWN
+            | 10051 // WSAENETUNREACH
+            | 10052 // WSAENETRESET
+            | 10054 // WSAECONNRESET
+            | 10060 // WSAETIMEDOUT
+            | 10061 // WSAECONNREFUSED
+            | 10064 // WSAEHOSTDOWN
+            | 10065 // WSAEHOSTUNREACH
+    )
+}
+
+#[cfg(not(any(unix, windows)))]
+fn is_transient_udp_os_error(_code: i32) -> bool {
+    false
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        is_transient_udp_error, is_transient_udp_send_error, recv_udp_retrying_transient,
+        send_udp_retrying_transient,
+    };
+    use std::time::Duration;
+    use tokio::net::UdpSocket;
+
+    #[test]
+    fn classifies_portable_transient_udp_errors() {
+        for kind in [
+            std::io::ErrorKind::Interrupted,
+            std::io::ErrorKind::TimedOut,
+            std::io::ErrorKind::WouldBlock,
+        ] {
+            let err = std::io::Error::from(kind);
+            assert!(is_transient_udp_error(&err));
+            assert!(is_transient_udp_send_error(&err));
+        }
+        let fatal = std::io::Error::from(std::io::ErrorKind::PermissionDenied);
+        assert!(!is_transient_udp_error(&fatal));
+        assert!(!is_transient_udp_send_error(&fatal));
+    }
+
+    #[tokio::test]
+    async fn retrying_udp_send_and_receive_round_trip() {
+        let receiver = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+        let sender = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+        let addr = receiver.local_addr().unwrap();
+
+        send_udp_retrying_transient(&sender, b"hello", addr, Duration::from_millis(50))
+            .await
+            .unwrap();
+        let mut buf = [0u8; 16];
+        let (n, peer) = recv_udp_retrying_transient(&receiver, &mut buf, Duration::from_millis(50))
+            .await
+            .unwrap();
+
+        assert_eq!(&buf[..n], b"hello");
+        assert_eq!(peer, sender.local_addr().unwrap());
+    }
+
+    #[tokio::test]
+    async fn retrying_udp_receive_times_out_cleanly() {
+        let receiver = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+        let mut buf = [0u8; 16];
+        let err = recv_udp_retrying_transient(&receiver, &mut buf, Duration::from_millis(1))
+            .await
+            .unwrap_err();
+
+        assert_eq!(err.kind(), std::io::ErrorKind::TimedOut);
+    }
+
+    #[cfg(unix)]
+    #[test]
+    fn classifies_unix_network_churn_as_transient() {
+        for code in [
+            libc::EADDRNOTAVAIL,
+            libc::ECONNREFUSED,
+            libc::ECONNRESET,
+            libc::EHOSTDOWN,
+            libc::EHOSTUNREACH,
+            libc::ENETDOWN,
+            libc::ENETRESET,
+            libc::ENETUNREACH,
+            libc::ETIMEDOUT,
+        ] {
+            let err = std::io::Error::from_raw_os_error(code);
+            assert!(is_transient_udp_error(&err));
+            assert!(is_transient_udp_send_error(&err));
+        }
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn classifies_windows_network_churn_as_transient() {
+        for code in [
+            10049, 10050, 10051, 10052, 10054, 10060, 10061, 10064, 10065,
+        ] {
+            let err = std::io::Error::from_raw_os_error(code);
+            assert!(is_transient_udp_error(&err));
+            assert!(is_transient_udp_send_error(&err));
+        }
+    }
+}

tests/hostile_network.rs

@@ -29,7 +29,7 @@ use std::io::{Read, Write};
 use std::net::{SocketAddr, TcpListener, UdpSocket};
 use std::process::{Child, Command, Stdio};
 use std::sync::Arc;
-use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicU32, AtomicU64, Ordering};
 use std::sync::mpsc::{Receiver, Sender, channel};
 use std::thread;
 use std::time::{Duration, Instant};
@@ -49,9 +49,20 @@ use ed25519_dalek::{SigningKey, VerifyingKey};
 use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
 
+const TEST_UDP_PORT_START: u16 = 31_000;
+const TEST_UDP_PORT_END: u16 = 60_999;
+static NEXT_UDP_PORT: AtomicU32 = AtomicU32::new(TEST_UDP_PORT_START as u32);
+
 fn free_udp_port() -> u16 {
-    let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
-    socket.local_addr().unwrap().port()
+    let span = u32::from(TEST_UDP_PORT_END - TEST_UDP_PORT_START) + 1;
+    for _ in TEST_UDP_PORT_START..=TEST_UDP_PORT_END {
+        let offset = NEXT_UDP_PORT.fetch_add(1, Ordering::SeqCst) % span;
+        let port = TEST_UDP_PORT_START + offset as u16;
+        if UdpSocket::bind(("127.0.0.1", port)).is_ok() {
+            return port;
+        }
+    }
+    panic!("no free UDP test port in {TEST_UDP_PORT_START}-{TEST_UDP_PORT_END}");
 }
 
 fn write_server_config(dir: &tempfile::TempDir, port: u16) -> std::path::PathBuf {
@@ -258,7 +269,8 @@ fn relay_loop(
     let mut upstream = new_upstream();
     let mut client_addr: Option<SocketAddr> = None;
     let mut rng = StdRng::seed_from_u64(seed);
-    let mut held: Option<(Vec<u8>, bool)> = None; // (packet, is_c2s) held for reorder
+    let mut held_c2s: Option<Vec<u8>> = None;
+    let mut held_s2c: Option<Vec<u8>> = None;
     let mut buf = [0u8; 65535];
 
     loop {
@@ -288,10 +300,9 @@ fn relay_loop(
                         &upstream,
                         server_addr,
                         packet,
-                        true,
                         &controls,
                         &mut rng,
-                        &mut held,
+                        &mut held_c2s,
                     );
                 }
             }
@@ -310,7 +321,12 @@ fn relay_loop(
                     let drop_pct = controls.drop_s2c_percent.load(Ordering::SeqCst);
                     if drop_pct == 0 || rng.gen_range(0..100) >= drop_pct {
                         forward_with_effects(
-                            &front, dst, packet, false, &controls, &mut rng, &mut held,
+                            &front,
+                            dst,
+                            packet,
+                            &controls,
+                            &mut rng,
+                            &mut held_s2c,
                         );
                     }
                 }
@@ -336,23 +352,22 @@ fn forward_with_effects(
     out: &UdpSocket,
     dst: SocketAddr,
     packet: Vec<u8>,
-    is_c2s: bool,
     controls: &RelayControls,
     rng: &mut StdRng,
-    held: &mut Option<(Vec<u8>, bool)>,
+    held: &mut Option<Vec<u8>>,
 ) {
     // Reorder: if armed, hold this packet and release the previously held one
     // afterward (so two consecutive packets swap order).
     if controls.reorder_next.swap(false, Ordering::SeqCst) {
-        if let Some((prev, _)) = held.take() {
+        if let Some(prev) = held.take() {
             let _ = out.send_to(&packet, dst);
             let _ = out.send_to(&prev, dst);
             return;
         }
-        *held = Some((packet, is_c2s));
+        *held = Some(packet);
         return;
     }
-    if let Some((prev, _)) = held.take() {
+    if let Some(prev) = held.take() {
         let _ = out.send_to(&prev, dst);
     }
 
@@ -767,6 +782,46 @@ fn wait_for_text(socket: &UdpSocket, key: &[u8; 32], needle: &str, millis: u64)
     acc.contains(needle)
 }
 
+fn wait_for_text_with_ack(
+    socket: &UdpSocket,
+    relay: &Relay,
+    client_id: [u8; 16],
+    seq: &mut u64,
+    key: &[u8; 32],
+    needle: &str,
+    millis: u64,
+) -> bool {
+    let prev = socket.read_timeout().unwrap();
+    socket
+        .set_read_timeout(Some(Duration::from_millis(100)))
+        .unwrap();
+    let deadline = Instant::now() + Duration::from_millis(millis);
+    let mut acc = String::new();
+    while Instant::now() < deadline {
+        if let Some((_header, frame)) = recv_frame(socket, key) {
+            acc.push_str(&String::from_utf8_lossy(&frame.bytes));
+            let ack = protocol::encode_encrypted(
+                PacketKind::Ack,
+                client_id,
+                *seq,
+                frame.output_seq,
+                key,
+                CLIENT_TO_SERVER,
+                b"",
+            )
+            .unwrap();
+            *seq += 1;
+            socket.send_to(&ack, relay.front_addr()).unwrap();
+            if acc.contains(needle) {
+                socket.set_read_timeout(prev).unwrap();
+                return true;
+            }
+        }
+    }
+    socket.set_read_timeout(prev).unwrap();
+    acc.contains(needle)
+}
+
 #[test]
 fn session_survives_packet_loss_and_reorder() {
     let dir = tempfile::tempdir().unwrap();
@@ -820,6 +875,94 @@ fn session_survives_packet_loss_and_reorder() {
     );
 }
 
+#[test]
+#[ignore = "30-minute hostile-network TUI soak; run with `DOSH_BADNET_SOAK_SECONDS=1800 cargo test --test hostile_network bad_network_tui_work_soak_30m -- --ignored --nocapture`"]
+fn bad_network_tui_work_soak_30m() {
+    let soak_secs = std::env::var("DOSH_BADNET_SOAK_SECONDS")
+        .ok()
+        .and_then(|value| value.parse::<u64>().ok())
+        .unwrap_or(30 * 60);
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    let mut server = start_server(&dir, &config);
+    let relay = Relay::spawn(port, 0xBADC0DEu64);
+    let (socket, bootstrap, ok) = attach_through_relay(&config, &relay);
+
+    relay.set_drop_c2s(15);
+    relay.set_drop_s2c(20);
+    relay.set_dup(10);
+
+    let deadline = Instant::now() + Duration::from_secs(soak_secs);
+    let mut seq = 2u64;
+    let mut iteration = 0u64;
+    while Instant::now() < deadline {
+        if iteration.is_multiple_of(2) {
+            relay.arm_reorder();
+        }
+        if iteration > 0 && iteration.is_multiple_of(7) {
+            let _ = relay.rebind_upstream();
+        }
+        if iteration > 0 && iteration.is_multiple_of(11) {
+            relay.set_drop_s2c(100);
+            thread::sleep(Duration::from_millis(750));
+            relay.set_drop_s2c(20);
+        }
+
+        let marker = format!("DOSH_BADNET_TUI_{iteration}");
+        let command = format!(
+            "stty -echo; \
+             printf '\\033[?1049h\\033[?2026h\\033[?25l'; \
+             for i in 1 2 3 4 5 6; do \
+               printf '\\033[%s;4H{} ⠀⠁⠃⠇⡇⣇⣧⣷⣿ █▇▆▅▄▃▂▁ %s\\033[0m' \"$i\" \"$i\"; \
+             done; \
+             printf '\\033[?25h\\033[?2026l\\033[?1049l'\n",
+            marker
+        );
+
+        let step_deadline = Instant::now() + Duration::from_secs(8);
+        let mut seen = false;
+        let mut attempts = 0;
+        while Instant::now() < step_deadline && attempts < 12 {
+            send_input(
+                &socket,
+                &relay,
+                ok.client_id,
+                seq,
+                0,
+                &bootstrap.session_key,
+                command.as_bytes(),
+            );
+            seq += 1;
+            attempts += 1;
+            if wait_for_text_with_ack(
+                &socket,
+                &relay,
+                ok.client_id,
+                &mut seq,
+                &bootstrap.session_key,
+                &marker,
+                500,
+            ) {
+                seen = true;
+                break;
+            }
+        }
+        assert!(
+            seen,
+            "TUI marker {marker} did not arrive during hostile-network soak"
+        );
+
+        iteration += 1;
+        thread::sleep(Duration::from_millis(500));
+    }
+
+    relay.clear_impairments();
+    drop(relay);
+    let _ = server.kill();
+    let _ = server.wait();
+}
+
 #[test]
 fn duplicated_and_replayed_input_is_applied_at_most_once() {
     let dir = tempfile::tempdir().unwrap();

tests/integration_smoke.rs

@@ -3,9 +3,11 @@
 use std::fs;
 use std::io::{Read, Write};
 use std::net::{TcpListener, TcpStream, UdpSocket};
+use std::os::unix::fs::PermissionsExt;
 use std::os::unix::net::{UnixListener, UnixStream};
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command, Stdio};
+use std::sync::atomic::{AtomicU32, Ordering};
 use std::sync::mpsc;
 use std::thread;
 use std::time::Duration;
@@ -18,18 +20,40 @@ use dosh::crypto;
 use dosh::native::{host_public_key, load_or_create_host_key, ssh_ed25519_public_blob, trust_host};
 use dosh::protocol::{
     self, AttachOk, AttachReject, BootstrapAttachRequest, CLIENT_TO_SERVER, Frame, Input,
-    PacketKind, Resize, ResumeRequest, SERVER_TO_CLIENT,
+    PacketKind, Resize, ResumeRequest, SERVER_TO_CLIENT, TicketAttachBody, TicketAttachEnvelope,
+    TicketAttachOkEnvelope,
 };
 use ed25519_dalek::{Signer, SigningKey, VerifyingKey};
 
+const TEST_PORT_START: u16 = 30_000;
+const TEST_PORT_END: u16 = 60_999;
+static NEXT_UDP_PORT: AtomicU32 = AtomicU32::new(TEST_PORT_START as u32);
+static NEXT_TCP_PORT: AtomicU32 = AtomicU32::new(TEST_PORT_START as u32);
+
+fn next_test_port(counter: &AtomicU32) -> u16 {
+    let span = u32::from(TEST_PORT_END - TEST_PORT_START) + 1;
+    let offset = counter.fetch_add(1, Ordering::SeqCst) % span;
+    TEST_PORT_START + offset as u16
+}
+
 fn free_udp_port() -> u16 {
-    let socket = UdpSocket::bind("127.0.0.1:0").unwrap();
-    socket.local_addr().unwrap().port()
+    for _ in TEST_PORT_START..=TEST_PORT_END {
+        let port = next_test_port(&NEXT_UDP_PORT);
+        if UdpSocket::bind(("127.0.0.1", port)).is_ok() {
+            return port;
+        }
+    }
+    panic!("no free UDP test port in {TEST_PORT_START}-{TEST_PORT_END}");
 }
 
 fn free_tcp_port() -> u16 {
-    let listener = TcpListener::bind("127.0.0.1:0").unwrap();
-    listener.local_addr().unwrap().port()
+    for _ in TEST_PORT_START..=TEST_PORT_END {
+        let port = next_test_port(&NEXT_TCP_PORT);
+        if TcpListener::bind(("127.0.0.1", port)).is_ok() {
+            return port;
+        }
+    }
+    panic!("no free TCP test port in {TEST_PORT_START}-{TEST_PORT_END}");
 }
 
 fn write_server_config(dir: &tempfile::TempDir, port: u16) -> std::path::PathBuf {
@@ -98,6 +122,35 @@ persist_sessions = false
     config
 }
 
+fn write_server_config_with_output_interval(
+    dir: &tempfile::TempDir,
+    port: u16,
+    output_frame_interval_ms: u64,
+) -> std::path::PathBuf {
+    let config = write_server_config(dir, port);
+    let mut raw = fs::read_to_string(&config).unwrap();
+    raw.push_str(&format!(
+        "output_frame_interval_ms = {output_frame_interval_ms}\n"
+    ));
+    fs::write(&config, raw).unwrap();
+    config
+}
+
+fn write_server_config_with_retransmit_window(
+    dir: &tempfile::TempDir,
+    port: u16,
+    retransmit_window: u64,
+) -> std::path::PathBuf {
+    let config = write_server_config(dir, port);
+    let mut raw = fs::read_to_string(&config).unwrap();
+    raw = raw.replace(
+        "retransmit_window = 256\n",
+        &format!("retransmit_window = {retransmit_window}\n"),
+    );
+    fs::write(&config, raw).unwrap();
+    config
+}
+
 fn start_server(dir: &tempfile::TempDir, config: &std::path::Path) -> Child {
     let server = env!("CARGO_BIN_EXE_dosh-server");
     let child = Command::new(server)
@@ -501,6 +554,75 @@ fn direct_attach_session(
     (socket, bootstrap, ok)
 }
 
+fn ticket_attach_session(
+    socket: &UdpSocket,
+    port: u16,
+    bootstrap: &dosh::auth::BootstrapResponse,
+    session: &str,
+    mode: &str,
+) -> AttachOk {
+    let client_nonce = crypto::random_12();
+    let request_key = crypto::hkdf32(
+        &bootstrap.attach_ticket_psk,
+        &client_nonce,
+        b"dosh/ticket-attach-request/v1",
+    )
+    .unwrap();
+    let body = protocol::to_body(&TicketAttachBody {
+        session: session.to_string(),
+        mode: mode.to_string(),
+        cols: 80,
+        rows: 24,
+        requested_env: Vec::new(),
+    })
+    .unwrap();
+    let ciphertext = crypto::seal(
+        &request_key,
+        &client_nonce,
+        b"dosh-ticket-attach-request-v1",
+        &body,
+    )
+    .unwrap();
+    let envelope = TicketAttachEnvelope {
+        ticket: bootstrap.attach_ticket.clone(),
+        client_nonce,
+        ciphertext,
+    };
+    let packet = protocol::encode_plain(
+        PacketKind::TicketAttachRequest,
+        [0u8; 16],
+        1,
+        0,
+        &protocol::to_body(&envelope).unwrap(),
+    )
+    .unwrap();
+    socket
+        .send_to(&packet, format!("127.0.0.1:{port}"))
+        .unwrap();
+    let mut buf = [0u8; 65535];
+    let (n, _) = socket.recv_from(&mut buf).unwrap();
+    let packet = protocol::decode(&buf[..n]).unwrap();
+    assert_eq!(packet.header.kind, PacketKind::AttachOk);
+    let envelope: TicketAttachOkEnvelope = protocol::from_body(&packet.body).unwrap();
+    let mut salt = Vec::with_capacity(24);
+    salt.extend_from_slice(&client_nonce);
+    salt.extend_from_slice(&envelope.server_nonce);
+    let response_key = crypto::hkdf32(
+        &bootstrap.attach_ticket_psk,
+        &salt,
+        b"dosh/ticket-attach-ok/v1",
+    )
+    .unwrap();
+    let plain = crypto::open(
+        &response_key,
+        &envelope.server_nonce,
+        b"dosh-ticket-attach-ok-v1",
+        &envelope.ciphertext,
+    )
+    .unwrap();
+    protocol::from_body(&plain).unwrap()
+}
+
 #[allow(clippy::too_many_arguments)]
 fn send_encrypted(
     socket: &UdpSocket,
@@ -760,7 +882,9 @@ fn native_doctor_checks_auth_without_opening_terminal() {
     assert!(output.status.success(), "stdout={stdout}\nstderr={stderr}");
     assert!(stdout.contains("[ok] native udp"), "stdout={stdout}");
     assert!(stdout.contains("[ok] native auth"), "stdout={stdout}");
-    assert!(stdout.contains("[ok] forwarding policy"), "stdout={stdout}");
+    assert!(stdout.contains("[ok] server policy"), "stdout={stdout}");
+    assert!(stdout.contains("file_transfer=true"), "stdout={stdout}");
+    assert!(stdout.contains("exec_command=true"), "stdout={stdout}");
 }
 
 #[test]
@@ -868,6 +992,372 @@ fn native_local_forward_background_smoke() {
     assert_eq!(&buf[..n], b"dosh-background-forward-ping");
 }
 
+#[test]
+fn native_file_copy_recursive_round_trip() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    write_native_client_auth(&dir, &config);
+    let mut server = start_server(&dir, &config);
+    let src = dir.path().join("srcdir");
+    fs::create_dir_all(src.join("nested")).unwrap();
+    fs::write(src.join("root.txt"), b"root file\n").unwrap();
+    fs::write(src.join("nested/child.txt"), b"child file\n").unwrap();
+    std::os::unix::fs::symlink("root.txt", src.join("root-link")).unwrap();
+    std::os::unix::fs::symlink("nested/child.txt", src.join("child-link")).unwrap();
+
+    let client_bin = env!("CARGO_BIN_EXE_dosh-client");
+    let upload = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("-r")
+        .arg(&src)
+        .arg("local:remote-copy")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        upload.status.success(),
+        "upload failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&upload.stdout),
+        String::from_utf8_lossy(&upload.stderr)
+    );
+
+    let remote_copy = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("-r")
+        .arg("local:remote-copy")
+        .arg("local:remote-copy-2")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        remote_copy.status.success(),
+        "remote copy failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&remote_copy.stdout),
+        String::from_utf8_lossy(&remote_copy.stderr)
+    );
+
+    let list = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("ls")
+        .arg("local:remote-copy-2")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        list.status.success(),
+        "ls failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&list.stdout),
+        String::from_utf8_lossy(&list.stderr)
+    );
+    let list_stdout = String::from_utf8_lossy(&list.stdout);
+    assert!(list_stdout.contains("root.txt"), "stdout={list_stdout}");
+    assert!(list_stdout.contains("nested"), "stdout={list_stdout}");
+
+    let cat = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cat")
+        .arg("local:remote-copy-2/root.txt")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        cat.status.success(),
+        "cat failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&cat.stdout),
+        String::from_utf8_lossy(&cat.stderr)
+    );
+    assert_eq!(String::from_utf8_lossy(&cat.stdout), "root file\n");
+
+    let downloaded = dir.path().join("downloaded");
+    let download = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("-r")
+        .arg("local:remote-copy-2")
+        .arg(&downloaded)
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        download.status.success(),
+        "download failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&download.stdout),
+        String::from_utf8_lossy(&download.stderr)
+    );
+    assert_eq!(
+        fs::read_to_string(downloaded.join("root.txt")).unwrap(),
+        "root file\n"
+    );
+    assert_eq!(
+        fs::read_to_string(downloaded.join("nested/child.txt")).unwrap(),
+        "child file\n"
+    );
+    assert_eq!(
+        fs::read_link(downloaded.join("root-link")).unwrap(),
+        PathBuf::from("root.txt")
+    );
+    assert_eq!(
+        fs::read_link(downloaded.join("child-link")).unwrap(),
+        PathBuf::from("nested/child.txt")
+    );
+
+    let remove = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("rm")
+        .arg("-r")
+        .arg("local:remote-copy")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        remove.status.success(),
+        "rm failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&remove.stdout),
+        String::from_utf8_lossy(&remove.stderr)
+    );
+
+    let _ = server.kill();
+    let _ = server.wait();
+}
+
+#[test]
+fn native_file_copy_resume_truncates_oversized_destinations() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    write_native_client_auth(&dir, &config);
+    let mut server = start_server(&dir, &config);
+    let client_bin = env!("CARGO_BIN_EXE_dosh-client");
+
+    let local_short = dir.path().join("short.txt");
+    fs::write(&local_short, b"short\n").unwrap();
+
+    let seed_remote = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("exec")
+        .arg("local")
+        .arg("printf 'short\\nSTALE' > \"$HOME/resume-upload.txt\"")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        seed_remote.status.success(),
+        "seed remote failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&seed_remote.stdout),
+        String::from_utf8_lossy(&seed_remote.stderr)
+    );
+
+    let resume_upload = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("--resume")
+        .arg(&local_short)
+        .arg("local:resume-upload.txt")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        resume_upload.status.success(),
+        "resume upload failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&resume_upload.stdout),
+        String::from_utf8_lossy(&resume_upload.stderr)
+    );
+
+    let cat_upload = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cat")
+        .arg("local:resume-upload.txt")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        cat_upload.status.success(),
+        "cat upload failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&cat_upload.stdout),
+        String::from_utf8_lossy(&cat_upload.stderr)
+    );
+    assert_eq!(String::from_utf8_lossy(&cat_upload.stdout), "short\n");
+
+    let seed_download = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("exec")
+        .arg("local")
+        .arg("printf 'tiny\\n' > \"$HOME/resume-download.txt\"")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        seed_download.status.success(),
+        "seed download failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&seed_download.stdout),
+        String::from_utf8_lossy(&seed_download.stderr)
+    );
+
+    let local_download = dir.path().join("resume-download-local.txt");
+    fs::write(&local_download, b"tiny\nSTALE").unwrap();
+    let resume_download = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("--resume")
+        .arg("local:resume-download.txt")
+        .arg(&local_download)
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        resume_download.status.success(),
+        "resume download failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&resume_download.stdout),
+        String::from_utf8_lossy(&resume_download.stderr)
+    );
+    assert_eq!(fs::read_to_string(&local_download).unwrap(), "tiny\n");
+
+    let _ = server.kill();
+    let _ = server.wait();
+}
+
+#[test]
+fn native_file_copy_resume_prefix_mismatch_preserves_destinations() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    write_native_client_auth(&dir, &config);
+    let mut server = start_server(&dir, &config);
+    let client_bin = env!("CARGO_BIN_EXE_dosh-client");
+
+    let local_upload = dir.path().join("upload-prefix.txt");
+    let remote_upload = dir.path().join("remote-upload.txt");
+    fs::write(&local_upload, b"local-prefix\n").unwrap();
+    fs::write(&remote_upload, b"remote-prefix-with-tail\n").unwrap();
+    fs::set_permissions(&local_upload, fs::Permissions::from_mode(0o755)).unwrap();
+    fs::set_permissions(&remote_upload, fs::Permissions::from_mode(0o600)).unwrap();
+
+    let bad_upload_resume = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("--resume")
+        .arg(&local_upload)
+        .arg("local:remote-upload.txt")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        !bad_upload_resume.status.success(),
+        "bad upload resume unexpectedly succeeded: stdout={} stderr={}",
+        String::from_utf8_lossy(&bad_upload_resume.stdout),
+        String::from_utf8_lossy(&bad_upload_resume.stderr)
+    );
+    assert_eq!(
+        fs::read_to_string(&remote_upload).unwrap(),
+        "remote-prefix-with-tail\n"
+    );
+    assert_eq!(
+        fs::metadata(&remote_upload).unwrap().permissions().mode() & 0o777,
+        0o600
+    );
+
+    fs::write(dir.path().join("remote-download.txt"), b"remote-download\n").unwrap();
+    let local_download = dir.path().join("download-prefix.txt");
+    fs::write(&local_download, b"local-download-with-tail\n").unwrap();
+
+    let bad_download_resume = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("cp")
+        .arg("--resume")
+        .arg("local:remote-download.txt")
+        .arg(&local_download)
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    assert!(
+        !bad_download_resume.status.success(),
+        "bad download resume unexpectedly succeeded: stdout={} stderr={}",
+        String::from_utf8_lossy(&bad_download_resume.stdout),
+        String::from_utf8_lossy(&bad_download_resume.stderr)
+    );
+    assert_eq!(
+        fs::read_to_string(&local_download).unwrap(),
+        "local-download-with-tail\n"
+    );
+
+    let _ = server.kill();
+    let _ = server.wait();
+}
+
+#[test]
+fn native_exec_command_smoke() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    write_native_client_auth(&dir, &config);
+    let mut server = start_server(&dir, &config);
+    let client_bin = env!("CARGO_BIN_EXE_dosh-client");
+    let output = Command::new(client_bin)
+        .arg("--dosh-host")
+        .arg("127.0.0.1")
+        .arg("--dosh-port")
+        .arg(port.to_string())
+        .arg("exec")
+        .arg("local")
+        .arg("printf out; printf err >&2")
+        .env("HOME", dir.path())
+        .output()
+        .unwrap();
+    let _ = server.kill();
+    let _ = server.wait();
+
+    assert!(
+        output.status.success(),
+        "exec failed: stdout={} stderr={}",
+        String::from_utf8_lossy(&output.stdout),
+        String::from_utf8_lossy(&output.stderr)
+    );
+    assert_eq!(String::from_utf8_lossy(&output.stdout), "out");
+    assert_eq!(String::from_utf8_lossy(&output.stderr), "err");
+}
+
 #[test]
 fn native_local_forward_bulk_load_does_not_delay_interactive_terminal() {
     use portable_pty::{CommandBuilder, NativePtySystem, PtySize, PtySystem};
@@ -1190,18 +1680,10 @@ fn server_retransmits_unacked_output_frames() {
     );
 
     let mut seen = Vec::new();
-    let mut duplicate = None;
-    let deadline = std::time::Instant::now() + Duration::from_secs(3);
+    let deadline = std::time::Instant::now() + Duration::from_secs(4);
     while std::time::Instant::now() < deadline {
         if let Some((header, frame)) = recv_frame(&socket, &bootstrap.session_key) {
             if String::from_utf8_lossy(&frame.bytes).contains("DOSH_RETRANSMIT") {
-                if seen
-                    .iter()
-                    .any(|(_, output_seq)| *output_seq == frame.output_seq)
-                {
-                    duplicate = Some((header.seq, frame.output_seq));
-                    break;
-                }
                 seen.push((header.seq, frame.output_seq));
             }
         }
@@ -1210,9 +1692,18 @@ fn server_retransmits_unacked_output_frames() {
     let _ = server.kill();
     let _ = server.wait();
 
+    let max_same_output_seq = seen
+        .iter()
+        .map(|(_, output_seq)| {
+            seen.iter()
+                .filter(|(_, candidate)| candidate == output_seq)
+                .count()
+        })
+        .max()
+        .unwrap_or(0);
     assert!(
-        duplicate.is_some(),
-        "expected retransmitted same output seq, seen={seen:?}"
+        max_same_output_seq >= 10,
+        "expected retransmission to continue past the old 8-attempt ceiling, seen={seen:?}"
     );
 }
 
@@ -1466,6 +1957,110 @@ fn unicode_output_survives_transport() {
     );
 }
 
+#[test]
+fn tui_graph_glyphs_survive_fast_repaints_without_snapshot_substitution() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config_with_output_interval(&dir, port, 1000);
+    let mut server = start_server(&dir, &config);
+    let (socket, bootstrap, ok) = direct_attach(&config, port, "read-write");
+
+    let graph = "DOSH_GRAPH ⣀⣤⣶⣿ █▇▆▅▄▃▂▁ ╭╮╯╰";
+    let input = Input {
+        bytes: format!(
+            "printf '\\033[?1049h\\033[?25l'; for i in 1 2 3 4 5; do printf '\\033[H{} %s\\n' \"$i\"; done; printf '\\033[?25h\\033[?1049l'\n",
+            graph
+        )
+        .into_bytes(),
+    };
+    send_encrypted(
+        &socket,
+        port,
+        PacketKind::Input,
+        ok.client_id,
+        2,
+        0,
+        &bootstrap.session_key,
+        &protocol::to_body(&input).unwrap(),
+    );
+    let text = collect_frame_text(&socket, &bootstrap.session_key, 3000);
+
+    let _ = server.kill();
+    let _ = server.wait();
+
+    assert!(
+        text.contains(graph) && text.matches("DOSH_GRAPH").count() >= 5,
+        "expected repeated raw graph glyph frames, got {text:?}"
+    );
+    assert!(
+        text.contains("\x1b[?25l") && text.contains("\x1b[?25h"),
+        "expected cursor visibility controls to survive around graph repaint, got {text:?}"
+    );
+}
+
+#[test]
+fn btop_style_graph_output_stays_raw_when_retransmit_history_overflows() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config_with_retransmit_window(&dir, port, 3);
+    let mut server = start_server(&dir, &config);
+    let (socket, bootstrap, ok) = direct_attach(&config, port, "read-write");
+
+    let graph = "DOSH_BTOP_NET ⠀⠁⠃⠇⡇⣇⣧⣷⣿";
+    let input = Input {
+        bytes: format!(
+            "stty -echo; \
+             printf '\\033[?1049h\\033[?2026h\\033[?25l'; \
+             for i in 1 2 3 4 5 6 7 8 9 10; do \
+               printf '\\033[6;4H\\033[38;2;80;220;140m{} %s\\033[0m' \"$i\"; \
+             done; \
+             printf '\\033[?25h\\033[?2026l\\033[?1049l'\n",
+            graph
+        )
+        .into_bytes(),
+    };
+    send_encrypted(
+        &socket,
+        port,
+        PacketKind::Input,
+        ok.client_id,
+        2,
+        0,
+        &bootstrap.session_key,
+        &protocol::to_body(&input).unwrap(),
+    );
+
+    let mut text = String::new();
+    let mut snapshots = 0usize;
+    let deadline = std::time::Instant::now() + Duration::from_secs(3);
+    while std::time::Instant::now() < deadline
+        && !(text.matches("DOSH_BTOP_NET").count() >= 10 && text.contains("\x1b[?2026l"))
+    {
+        if let Some((_header, frame)) = recv_frame(&socket, &bootstrap.session_key) {
+            if frame.snapshot {
+                snapshots += 1;
+            }
+            text.push_str(&String::from_utf8_lossy(&frame.bytes));
+        }
+    }
+
+    let _ = server.kill();
+    let _ = server.wait();
+
+    assert_eq!(
+        snapshots, 0,
+        "live btop-style graph output must not be replaced by snapshots; got {snapshots}"
+    );
+    assert!(
+        text.matches("DOSH_BTOP_NET").count() >= 10
+            && text.contains("⣿")
+            && text.contains("\x1b[38;2;80;220;140m")
+            && text.contains("\x1b[?2026h")
+            && text.contains("\x1b[?2026l"),
+        "expected raw btop-style graph output to survive under retransmit pressure, got {text:?}"
+    );
+}
+
 #[test]
 fn large_tui_paint_is_delivered_in_mtu_safe_frames() {
     let dir = tempfile::tempdir().unwrap();
@@ -2212,6 +2807,9 @@ fn write_persistent_server_config(dir: &tempfile::TempDir, port: u16) -> std::pa
     let mut raw = fs::read_to_string(&config).unwrap();
     // The base writer hardcodes `persist_sessions = false`; flip it on.
     raw = raw.replace("persist_sessions = false", "persist_sessions = true");
+    // Persistence tests attach the sessions they need explicitly. Leaving the
+    // base prewarm on here creates a detached default holder in every test.
+    raw = raw.replace("prewarm_sessions = [\"default\"]", "prewarm_sessions = []");
     fs::write(&config, raw).unwrap();
     config
 }
@@ -2247,6 +2845,45 @@ fn kill_holder(sessions_dir: &Path, session: &str) {
         .status();
 }
 
+/// Create a holder the way older Dosh builds did for implicit sessions, so
+/// startup migration can be tested without depending on the new spawn policy.
+fn spawn_legacy_holder(sessions_dir: &Path, session: &str) {
+    let server = env!("CARGO_BIN_EXE_dosh-server");
+    let runtime_dir = dosh::persist::ensure_runtime_dir(sessions_dir, session).unwrap();
+    let mut launcher = Command::new(server)
+        .arg("hold")
+        .arg("--runtime-dir")
+        .arg(&runtime_dir)
+        .arg("--session")
+        .arg(session)
+        .arg("--shell")
+        .arg("/bin/sh")
+        .arg("--cols")
+        .arg("80")
+        .arg("--rows")
+        .arg("24")
+        .stdout(Stdio::null())
+        .stderr(Stdio::null())
+        .spawn()
+        .unwrap();
+    let deadline = std::time::Instant::now() + Duration::from_secs(5);
+    while std::time::Instant::now() < deadline {
+        if holder_shell_pid(sessions_dir, session).is_some()
+            && runtime_dir.join("holder.sock").exists()
+        {
+            let _ = launcher.wait();
+            return;
+        }
+        if let Some(status) = launcher.try_wait().unwrap() {
+            panic!("legacy holder launcher exited before ready: {status}");
+        }
+        thread::sleep(Duration::from_millis(20));
+    }
+    let _ = launcher.kill();
+    let _ = launcher.wait();
+    panic!("legacy holder did not become ready");
+}
+
 /// Send one encrypted Input line and give the shell a moment to act.
 fn type_line(socket: &UdpSocket, port: u16, ok: &AttachOk, key: &[u8; 32], seq: u64, line: &str) {
     let input = Input {
@@ -2384,7 +3021,7 @@ fn session_survives_server_restart_same_shell_and_screen() {
 }
 
 #[test]
-fn implicit_session_survives_server_restart_for_same_ticket_holder() {
+fn implicit_session_survives_update_restart_via_ticket_reattach() {
     let dir = tempfile::tempdir().unwrap();
     let sessions_dir = dir.path().join("sessions");
     let port = free_udp_port();
@@ -2394,59 +3031,140 @@ fn implicit_session_survives_server_restart_for_same_ticket_holder() {
     let mut server = start_server(&dir, &config);
     let (socket, bootstrap, ok) = direct_attach_session(&config, port, "read-write", &session);
     let key = bootstrap.session_key;
+    type_line(&socket, port, &ok, &key, 2, "cd /tmp\n");
     type_line(
         &socket,
         port,
         &ok,
         &key,
-        2,
+        3,
         "export IMPLICIT_MARK=implicit_restart_42\n",
     );
-    let _ = collect_frame_text(&socket, &key, 1000);
+    type_line(
+        &socket,
+        port,
+        &ok,
+        &key,
+        4,
+        "printf 'IMPLICIT_SCREEN_MARKER\\n'\n",
+    );
+    let pre = collect_frame_text(&socket, &key, 1500);
+    assert!(
+        pre.contains("IMPLICIT_SCREEN_MARKER"),
+        "implicit marker missing before restart: {pre:?}"
+    );
     thread::sleep(Duration::from_secs(3));
 
     let shell_pid_before = holder_shell_pid(&sessions_dir, &session);
     assert!(
         shell_pid_before.is_some(),
-        "implicit sessions should get a persistent holder when persistence is enabled"
+        "implicit sessions must get temporary holders so active clients survive updates"
     );
 
     let _ = server.kill();
     let _ = server.wait();
     thread::sleep(Duration::from_millis(300));
 
-    let pid = shell_pid_before.unwrap();
-    assert!(
-        unsafe { libc::kill(pid, 0) } == 0,
-        "implicit session shell pid {pid} must survive server restart"
-    );
-
     let mut server = start_server(&dir, &config);
-    let (socket2, bootstrap2, ok2) = direct_attach_session(&config, port, "read-write", &session);
-    let key2 = bootstrap2.session_key;
+
+    let resume = ResumeRequest {
+        session: session.clone(),
+        last_rendered_seq: ok.initial_seq,
+        cols: 80,
+        rows: 24,
+    };
+    send_encrypted(
+        &socket,
+        port,
+        PacketKind::ResumeRequest,
+        ok.client_id,
+        5,
+        0,
+        &key,
+        &protocol::to_body(&resume).unwrap(),
+    );
+    let mut buf = [0u8; 65535];
+    let deadline = std::time::Instant::now() + Duration::from_secs(2);
+    loop {
+        assert!(
+            std::time::Instant::now() < deadline,
+            "old live resume did not receive unknown-client reject"
+        );
+        let (n, _) = socket.recv_from(&mut buf).unwrap();
+        let packet = protocol::decode(&buf[..n]).unwrap();
+        if packet.header.kind == PacketKind::Frame {
+            continue;
+        }
+        assert_eq!(packet.header.kind, PacketKind::AttachReject);
+        assert_eq!(packet.header.conn_id, ok.client_id);
+        break;
+    }
+
+    let ok2 = ticket_attach_session(&socket, port, &bootstrap, &session, "read-write");
+    let key2 = ok2.session_key;
+    let snapshot = String::from_utf8_lossy(&ok2.snapshot).to_string();
     type_line(
-        &socket2,
+        &socket,
         port,
         &ok2,
         &key2,
         2,
-        "printf 'IMPLICIT_MARK=%s\\n' \"$IMPLICIT_MARK\"\n",
+        "printf 'IMPLICIT_MARK=%s PWD=%s\\n' \"$IMPLICIT_MARK\" \"$PWD\"\n",
     );
-    let post = collect_frame_text(&socket2, &key2, 2000);
+    let post = collect_frame_text(&socket, &key2, 2000);
     let shell_pid_after = holder_shell_pid(&sessions_dir, &session);
 
     let _ = server.kill();
     let _ = server.wait();
     kill_holder(&sessions_dir, &session);
 
+    assert!(
+        snapshot.contains("IMPLICIT_SCREEN_MARKER"),
+        "ticket reattach snapshot must repaint the exact pre-update screen, got {snapshot:?}"
+    );
     assert_eq!(
         shell_pid_after, shell_pid_before,
-        "implicit session should re-adopt the same shell pid"
+        "implicit update reconnect must use the same holder shell"
     );
     assert!(
         post.contains("IMPLICIT_MARK=implicit_restart_42"),
-        "implicit session state must survive restart, got {post:?}"
+        "implicit session env must survive update reconnect, got {post:?}"
     );
+    assert!(
+        post.contains("PWD=/tmp"),
+        "implicit session cwd must survive update reconnect, got {post:?}"
+    );
+}
+
+#[test]
+fn startup_readopts_implicit_holders_for_update_reconnect() {
+    let dir = tempfile::tempdir().unwrap();
+    let sessions_dir = dir.path().join("sessions");
+    let port = free_udp_port();
+    let config = write_persistent_server_config(&dir, port);
+    let session = protocol::generate_implicit_session_name();
+
+    spawn_legacy_holder(&sessions_dir, &session);
+    let shell_pid = holder_shell_pid(&sessions_dir, &session).expect("legacy holder shell pid");
+    assert!(
+        unsafe { libc::kill(shell_pid, 0) } == 0,
+        "legacy holder shell must be live before startup"
+    );
+
+    let mut server = start_server(&dir, &config);
+    thread::sleep(Duration::from_millis(300));
+
+    let _ = server.kill();
+    let _ = server.wait();
+    assert!(
+        holder_shell_pid(&sessions_dir, &session).is_some(),
+        "startup must keep live implicit holders so active update reconnects can reattach"
+    );
+    assert!(
+        unsafe { libc::kill(shell_pid, 0) } == 0,
+        "startup must not shut down a live implicit holder before reconnect grace"
+    );
+    kill_holder(&sessions_dir, &session);
 }
 
 #[test]

tests/protocol_auth.rs

@@ -58,6 +58,19 @@ fn encrypted_packet_round_trips() {
     assert_eq!(plain, b"hello");
 }
 
+#[test]
+fn plaintext_packet_never_decrypts_as_authenticated_body() {
+    let key = crypto::random_32();
+    let mut decoded = protocol::decode(
+        &protocol::encode_plain(PacketKind::Input, crypto::random_16(), 1, 0, b"hello").unwrap(),
+    )
+    .unwrap();
+    decoded.header.session_key_id = protocol::session_key_id(&key);
+
+    let err = protocol::decrypt_body(&decoded, &key, CLIENT_TO_SERVER).unwrap_err();
+    assert!(err.to_string().contains("not encrypted"));
+}
+
 #[test]
 fn encrypted_packet_rejects_wrong_session_key_id_before_decrypt() {
     let key = crypto::random_32();

tests/release_scripts.rs

@@ -0,0 +1,92 @@
+#[test]
+fn quiet_update_keeps_prebuilt_enabled_by_default() {
+    let install = include_str!("../install.sh");
+    assert!(install.contains("use_prebuilt=\"${DOSH_USE_PREBUILT:-1}\""));
+    assert!(
+        !install.contains("use_prebuilt=0"),
+        "quiet updates must not force source builds"
+    );
+}
+
+#[test]
+fn release_scripts_skip_stale_artifacts_when_auto_discovering() {
+    let upload = include_str!("../scripts/upload-gitea-release.sh");
+    assert!(upload.contains("skipping $artifact: version"));
+    assert!(upload.contains("expected_version"));
+
+    let publish = include_str!("../scripts/publish-gitea-release.sh");
+    assert!(publish.contains("skipping stale artifact"));
+    assert!(publish.contains("actual=\"$(artifact_version \"$artifact\" || true)\""));
+}
+
+#[test]
+fn package_check_verifies_only_artifacts_it_builds() {
+    let makefile = include_str!("../Makefile");
+    let verify = include_str!("../scripts/verify-release-artifacts.sh");
+    assert!(
+        verify.contains("if [ \"$#\" -gt 0 ]; then"),
+        "release verifier must accept an explicit artifact list"
+    );
+    let package_check = makefile
+        .split("package-check:")
+        .nth(1)
+        .and_then(|tail| tail.split("\ninstall:").next())
+        .expect("package-check target");
+    assert!(package_check.contains("package-release-linux"));
+    assert!(package_check.contains("package-release-windows"));
+    assert!(package_check.contains("dosh-linux-x86_64.tar.gz"));
+    assert!(package_check.contains("dosh-windows-x86_64.zip"));
+    assert!(
+        !package_check.contains("dosh-macos-aarch64.tar.gz"),
+        "Linux package-check does not build macOS artifacts, so it must not depend on one"
+    );
+}
+
+#[test]
+fn package_release_stamps_git_build_info() {
+    let package = include_str!("../scripts/package-release.sh");
+    let build = include_str!("../build.rs");
+    for name in [
+        "DOSH_BUILD_GIT_HASH",
+        "DOSH_BUILD_COMMIT_DATE",
+        "DOSH_BUILD_GIT_DIRTY",
+    ] {
+        assert!(package.contains(name), "package script must export {name}");
+        assert!(build.contains(name), "build.rs must consume {name}");
+    }
+    assert!(package.contains("git rev-parse --short=12 HEAD"));
+    assert!(package.contains("git show -s --format=%cs HEAD"));
+    assert!(build.contains("cargo:rerun-if-env-changed=DOSH_BUILD_GIT_HASH"));
+}
+
+#[test]
+fn systemd_service_does_not_sandbox_remote_shells() {
+    let service = include_str!("../packaging/systemd/dosh-server.service");
+    let install = include_str!("../install.sh");
+    for raw in [service, install] {
+        assert!(raw.contains("KillMode=process"));
+        assert!(
+            raw.contains("Restart=always"),
+            "dosh-server should come back after accidental SIGTERM while preserving child shells"
+        );
+        for directive in [
+            "NoNewPrivileges=",
+            "PrivateTmp=",
+            "ProtectSystem=",
+            "ProtectHome=",
+            "RestrictAddressFamilies=",
+            "RestrictRealtime=",
+            "LockPersonality=",
+            "MemoryDenyWriteExecute=",
+        ] {
+            assert!(
+                !raw.contains(directive),
+                "dosh sessions are user shells; systemd sandbox directive {directive} changes terminal/app behavior"
+            );
+        }
+        assert!(
+            !raw.contains("ReadWritePaths="),
+            "remote shells must not be restricted to dosh config/data paths"
+        );
+    }
+}

vscode-extension/README.md

@@ -0,0 +1,15 @@
+# Dosh Remote
+
+Open VS Code Remote-SSH windows through Dosh.
+
+The extension writes a managed SSH config entry like:
+
+```sshconfig
+Host dosh-palav
+    HostName 127.0.0.1
+    HostKeyAlias palav
+    ProxyCommand dosh proxy-stdio palav %h %p
+```
+
+VS Code still uses Remote-SSH, so server install, extensions, terminals, and
+normal SSH behavior stay intact. Dosh carries the SSH TCP byte stream.

vscode-extension/extension.js

@@ -0,0 +1,170 @@
+const vscode = require('vscode');
+const fs = require('fs');
+const os = require('os');
+const path = require('path');
+
+function activate(context) {
+  context.subscriptions.push(
+    vscode.commands.registerCommand('dosh.openRemote', openRemote),
+    vscode.commands.registerCommand('dosh.configureHost', configureHostCommand),
+    vscode.commands.registerCommand('dosh.showSshConfig', showSshConfig)
+  );
+}
+
+async function openRemote() {
+  const configured = await configureHost();
+  if (!configured) {
+    return;
+  }
+  const remotePath = await vscode.window.showInputBox({
+    title: 'Remote path',
+    prompt: 'Path to open on the remote host',
+    value: '~'
+  });
+  if (remotePath === undefined) {
+    return;
+  }
+  const suffix = remotePath ? `/${remotePath.replace(/^\/+/, '')}` : '';
+  await vscode.commands.executeCommand(
+    'vscode.openFolder',
+    vscode.Uri.parse(`vscode-remote://ssh-remote+${configured.alias}${suffix}`),
+    { forceNewWindow: true }
+  );
+}
+
+async function configureHostCommand() {
+  const configured = await configureHost();
+  if (configured) {
+    vscode.window.showInformationMessage(`Dosh Remote-SSH host ready: ${configured.alias}`);
+  }
+}
+
+async function configureHost() {
+  const host = await vscode.window.showInputBox({
+    title: 'Dosh host',
+    prompt: 'Dosh host alias, e.g. palav',
+    ignoreFocusOut: true
+  });
+  if (!host) {
+    return undefined;
+  }
+  const user = await vscode.window.showInputBox({
+    title: 'Remote SSH user',
+    prompt: 'Optional. Leave blank to let SSH config decide.',
+    ignoreFocusOut: true
+  });
+  const config = vscode.workspace.getConfiguration('dosh');
+  const alias = `dosh-${safeAlias(host)}`;
+  const block = sshBlock({
+    alias,
+    host,
+    user: user || undefined,
+    executable: config.get('executable') || 'dosh',
+    targetHost: config.get('targetHost') || '127.0.0.1',
+    targetPort: Number(config.get('targetPort') || 22),
+    doshPort: Number(config.get('doshPort') || 0)
+  });
+  const sshDir = path.join(os.homedir(), '.ssh');
+  fs.mkdirSync(sshDir, { recursive: true });
+  const generatedPath = config.get('generatedSshConfig') || path.join(sshDir, 'config.dosh');
+  const mainConfig = path.join(sshDir, 'config');
+  ensureInclude(mainConfig, path.basename(generatedPath));
+  upsertBlock(generatedPath, alias, block);
+  return { alias, generatedPath };
+}
+
+function sshBlock(options) {
+  let proxy = shellQuote(options.executable);
+  if (options.doshPort > 0) {
+    proxy += ` --dosh-port ${options.doshPort}`;
+  }
+  proxy += ` proxy-stdio ${shellQuote(options.host)} %h %p`;
+  const lines = [
+    `# BEGIN DOSH ${options.alias}`,
+    `Host ${options.alias}`,
+    `    HostName ${options.targetHost}`,
+    `    Port ${options.targetPort}`,
+    `    HostKeyAlias ${options.host}`,
+    options.user ? `    User ${options.user}` : undefined,
+    '    ClearAllForwardings yes',
+    '    ServerAliveInterval 15',
+    '    ServerAliveCountMax 3',
+    `    ProxyCommand ${proxy}`,
+    `# END DOSH ${options.alias}`,
+    ''
+  ].filter(Boolean);
+  return lines.join('\n');
+}
+
+function ensureInclude(configPath, includeFile) {
+  const raw = fs.existsSync(configPath) ? fs.readFileSync(configPath, 'utf8') : '';
+  if (raw.split(/\r?\n/).some((line) => line.trim().toLowerCase() === `include ${includeFile}`.toLowerCase())) {
+    return;
+  }
+  fs.writeFileSync(configPath, `Include ${includeFile}\n${raw ? `\n${raw}` : ''}`);
+}
+
+function upsertBlock(configPath, alias, block) {
+  const raw = fs.existsSync(configPath) ? fs.readFileSync(configPath, 'utf8') : '';
+  const begin = `# BEGIN DOSH ${alias}`;
+  const end = `# END DOSH ${alias}`;
+  const lines = raw.split(/\r?\n/);
+  const out = [];
+  let skipping = false;
+  let replaced = false;
+  for (const line of lines) {
+    if (line.trim() === begin) {
+      out.push(block.trimEnd());
+      skipping = true;
+      replaced = true;
+      continue;
+    }
+    if (skipping) {
+      if (line.trim() === end) {
+        skipping = false;
+      }
+      continue;
+    }
+    if (line.length > 0 || out.length > 0) {
+      out.push(line);
+    }
+  }
+  if (!replaced) {
+    if (out.length > 0 && out[out.length - 1] !== '') {
+      out.push('');
+    }
+    out.push(block.trimEnd());
+  }
+  fs.writeFileSync(configPath, `${out.join('\n').trimEnd()}\n`);
+}
+
+async function showSshConfig() {
+  const config = vscode.workspace.getConfiguration('dosh');
+  const sshDir = path.join(os.homedir(), '.ssh');
+  const generatedPath = config.get('generatedSshConfig') || path.join(sshDir, 'config.dosh');
+  if (!fs.existsSync(generatedPath)) {
+    vscode.window.showWarningMessage('No generated Dosh SSH config yet.');
+    return;
+  }
+  const doc = await vscode.workspace.openTextDocument(generatedPath);
+  await vscode.window.showTextDocument(doc);
+}
+
+function safeAlias(value) {
+  const alias = value.replace(/[^a-zA-Z0-9_-]+/g, '-').replace(/^-+|-+$/g, '');
+  return alias || 'host';
+}
+
+function shellQuote(value) {
+  if (/^[a-zA-Z0-9_./:-]+$/.test(value)) {
+    return value;
+  }
+  return `'${value.replace(/'/g, `'\\''`)}'`;
+}
+
+function deactivate() {}
+
+module.exports = {
+  activate,
+  deactivate
+};

vscode-extension/package.json

@@ -0,0 +1,69 @@
+{
+  "name": "dosh-vscode",
+  "displayName": "Dosh Remote",
+  "description": "Open VS Code Remote-SSH windows through Dosh.",
+  "version": "0.1.0",
+  "publisher": "palav",
+  "license": "MIT",
+  "engines": {
+    "vscode": "^1.90.0"
+  },
+  "categories": [
+    "Other"
+  ],
+  "extensionDependencies": [
+    "ms-vscode-remote.remote-ssh"
+  ],
+  "activationEvents": [
+    "onCommand:dosh.openRemote",
+    "onCommand:dosh.configureHost",
+    "onCommand:dosh.showSshConfig"
+  ],
+  "main": "./extension.js",
+  "contributes": {
+    "commands": [
+      {
+        "command": "dosh.openRemote",
+        "title": "Dosh: Open Remote Folder"
+      },
+      {
+        "command": "dosh.configureHost",
+        "title": "Dosh: Configure Remote-SSH Host"
+      },
+      {
+        "command": "dosh.showSshConfig",
+        "title": "Dosh: Show Generated SSH Config"
+      }
+    ],
+    "configuration": {
+      "title": "Dosh Remote",
+      "properties": {
+        "dosh.executable": {
+          "type": "string",
+          "default": "dosh",
+          "description": "Path to the local dosh executable."
+        },
+        "dosh.targetHost": {
+          "type": "string",
+          "default": "127.0.0.1",
+          "description": "Host opened from the Dosh server side for VS Code's SSH connection."
+        },
+        "dosh.targetPort": {
+          "type": "number",
+          "default": 22,
+          "description": "SSH port opened from the Dosh server side."
+        },
+        "dosh.doshPort": {
+          "type": "number",
+          "default": 0,
+          "description": "Optional Dosh UDP port override. 0 uses Dosh config."
+        },
+        "dosh.generatedSshConfig": {
+          "type": "string",
+          "default": "",
+          "description": "Path for generated SSH config. Empty means ~/.ssh/config.dosh."
+        }
+      }
+    }
+  }
+}