Prevent update from using stale latest release

.github/workflows/ci.yml

@@ -86,6 +86,39 @@ jobs:
             target/dosh-release/dosh-*
             !target/dosh-release/stage/**
 
+  publish-gitea-release:
+    if: github.event_name == 'workflow_dispatch' || startsWith(github.ref, 'refs/tags/')
+    needs: package-release
+    runs-on: ubuntu-latest
+    env:
+      GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+      GITEA_URL: ${{ secrets.GITEA_URL || 'https://git.palav.dev' }}
+      GITEA_REPO: ${{ secrets.GITEA_REPO || 'Palav/dosh' }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
+        with:
+          pattern: dosh-*
+          path: target/dosh-release
+          merge-multiple: true
+      - name: Verify release artifacts
+        run: sh scripts/verify-release-artifacts.sh
+      - name: Skip Gitea upload without token
+        if: env.GITEA_TOKEN == ''
+        run: echo "GITEA_TOKEN secret is not configured; release artifacts were verified but not uploaded."
+      - name: Upload Gitea release assets
+        if: env.GITEA_TOKEN != ''
+        run: |
+          set -eu
+          case "$GITHUB_REF" in
+            refs/tags/*) tag="${GITHUB_REF_NAME}" ;;
+            *)
+              version="$(sed -n 's/^version = "\(.*\)"/\1/p' Cargo.toml | sed -n '1p')"
+              tag="v$version"
+              ;;
+          esac
+          scripts/upload-gitea-release.sh "$tag"
+
   remote-bench:
     runs-on: ubuntu-latest
     env:

Cargo.lock

@@ -436,7 +436,7 @@ dependencies = [
 
 [[package]]
 name = "dosh"
-version = "0.1.7"
+version = "1.0.0-rc42"
 dependencies = [
  "anyhow",
  "base64",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dosh"
-version = "0.1.7"
+version = "1.0.0-rc42"
 edition = "2024"
 license = "MIT"
 

Makefile

@@ -1,4 +1,4 @@
-.PHONY: build test fmt clippy release-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
+.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
@@ -19,6 +19,27 @@ release-check:
 	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

@@ -44,6 +44,7 @@ dosh setup HOST
 dosh HOST
 dosh HOST COMMAND
 dosh update
+dosh update --client|--server|--both
 ```
 
 Useful commands:
@@ -67,6 +68,32 @@ dosh restart HOST
 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. Reports default to the latest traced client/server
+process run; add `--all-runs` to include older appended log entries. 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:
@@ -97,6 +124,20 @@ 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.

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 hash = env::var("DOSH_BUILD_GIT_HASH")
-    let date = git(&["show", "-s", "--format=%cs", "HEAD"]).unwrap_or_else(|| "unknown".into());
+        .ok()
-    let dirty = Command::new("git")
+        .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("");
+            .unwrap_or(""),
+    };
 
     println!("cargo:rustc-env=DOSH_GIT_HASH={hash}{dirty}");
     println!("cargo:rustc-env=DOSH_COMMIT_DATE={date}");

install.ps1

@@ -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
+        Install-Binary "target\release\dosh-client.exe" (Join-Path $bindir "dosh-client.exe")
-        Copy-Item "target\release\dosh-client.exe" (Join-Path $bindir "dosh.exe") -Force
+        Install-Binary "target\release\dosh-client.exe" (Join-Path $bindir "dosh.exe")
-        Copy-Item "target\release\dosh-bench.exe" (Join-Path $bindir "dosh-bench.exe") -Force
+        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" ] && [ "${DOSH_BINARY_REQUIRED:-0}" != "1" ]; then
+use_prebuilt="${DOSH_USE_PREBUILT:-1}"
-  use_prebuilt=0
-else
-  use_prebuilt="${DOSH_USE_PREBUILT:-1}"
-fi
 binary_url="${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_binary target/release/dosh-server "$bindir/dosh-server"
-    install -m 0755 target/release/dosh-auth "$bindir/dosh-auth"
+    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
 }
 
@@ -417,18 +426,9 @@ Wants=network-online.target
 [Service]
 Type=simple
 ExecStart=$bindir/dosh-server serve
-Restart=on-failure
+Restart=always
 RestartSec=1
 KillMode=process
-NoNewPrivileges=true
-PrivateTmp=true
-ProtectSystem=strict
-ProtectHome=read-only
-ReadWritePaths=$config_dir $data_dir
-RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
-RestrictRealtime=true
-LockPersonality=true
-MemoryDenyWriteExecute=true
 
 [Install]
 WantedBy=default.target

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-macos-x86_64.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

@@ -13,6 +13,7 @@ use crate::protocol::{
 };
 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;
@@ -214,10 +215,10 @@ impl DoshClientBuilder {
                 hello: hello.clone(),
             })?,
         )?;
-        socket.send_to(&packet, peer_addr).await?;
+        send_udp_retrying_transient(&socket, &packet, peer_addr, timeout).await?;
 
         let mut buf = vec![0u8; 65535];
-        let (n, _) = tokio::time::timeout(timeout, socket.recv_from(&mut buf)).await??;
+        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 {
@@ -261,8 +262,8 @@ impl DoshClientBuilder {
             CLIENT_TO_SERVER,
             &protocol::to_body(&NativeUserAuthBody { auth })?,
         )?;
-        socket.send_to(&auth_packet, peer_addr).await?;
+        send_udp_retrying_transient(&socket, &auth_packet, peer_addr, timeout).await?;
-        let (n, _) = tokio::time::timeout(timeout, socket.recv_from(&mut buf)).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 {

src/config.rs

@@ -150,6 +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/file_transfer.rs

@@ -18,6 +18,14 @@ pub enum FileRequest {
         path: String,
         mode: Option<u32>,
     },
+    Readlink {
+        path: String,
+    },
+    Symlink {
+        path: String,
+        target: String,
+        overwrite: bool,
+    },
     Remove {
         path: String,
         recursive: bool,
@@ -46,13 +54,35 @@ pub enum FileRequest {
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 pub enum FileResponse {
     Ok,
-    Resume { offset: u64 },
+    Resume {
-    Stat { meta: FileMeta },
+        offset: u64,
-    List { entries: Vec<FileEntry> },
+        prefix_sha256: Option<[u8; 32]>,
-    Start { meta: FileMeta, offset: u64 },
+    },
-    Chunk { offset: u64, bytes: Vec<u8> },
+    Stat {
-    Done { sha256: [u8; 32], bytes: u64 },
+        meta: FileMeta,
-    Error { message: String },
+    },
+    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)]

src/lib.rs

@@ -22,4 +22,6 @@ pub mod protocol;
 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();

src/server.rs

@@ -13,6 +13,7 @@ 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};
@@ -97,6 +98,7 @@ pub enum DoshServerEvent {
     Ignored,
 }
 
+#[derive(Debug, Clone)]
 struct PendingServerAuth {
     client: native::NativeClientHello,
     server: NativeServerHello,
@@ -167,7 +169,11 @@ impl DoshServer {
         let mut buf = vec![0u8; 65535];
         loop {
             self.expire_pending();
-            let (n, peer) = self.socket.recv_from(&mut buf).await?;
+            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,
@@ -255,7 +261,7 @@ impl DoshServer {
         };
         let body = protocol::to_body(&NativeServerHelloBody { hello })?;
         let out = protocol::encode_plain(PacketKind::NativeServerHello, pending_id, 1, 0, &body)?;
-        self.socket.send_to(&out, peer).await?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
         Ok(())
     }
 
@@ -327,7 +333,7 @@ impl DoshServer {
         peer: SocketAddr,
         packet: &protocol::Packet,
     ) -> Result<DoshServerEvent> {
-        let Some(pending) = self.pending.remove(&packet.header.conn_id) else {
+        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);
@@ -338,13 +344,28 @@ impl DoshServer {
             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 = protocol::decrypt_body(packet, &pending.session_key, CLIENT_TO_SERVER)?;
+        let body = match protocol::decrypt_body(packet, &pending.session_key, CLIENT_TO_SERVER) {
-        let req: NativeUserAuthBody = protocol::from_body(&body)?;
+            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) => {
@@ -353,6 +374,7 @@ impl DoshServer {
                 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);
@@ -381,7 +403,7 @@ impl DoshServer {
             SERVER_TO_CLIENT,
             &body,
         )?;
-        self.socket.send_to(&out, peer).await?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
 
         let transport = DoshTransport::new(
             Arc::clone(&self.socket),
@@ -428,7 +450,7 @@ impl DoshServer {
             reason: reason.to_string(),
         })?;
         let out = protocol::encode_plain(PacketKind::AttachReject, conn_id, 0, 0, &body)?;
-        self.socket.send_to(&out, peer).await?;
+        let _ = send_udp(&self.socket, &out, peer).await?;
         Ok(())
     }
 
@@ -439,6 +461,14 @@ impl DoshServer {
     }
 }
 
+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],
@@ -477,6 +507,7 @@ 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;
 
@@ -588,4 +619,91 @@ mod tests {
             }
         }
     }
+
+    #[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 +1,223 @@
+use std::fs::{File, OpenOptions};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::sync::{Mutex, OnceLock};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+static TRACE_FILE: OnceLock<Option<Mutex<File>>> = OnceLock::new();
+static HEALTH_FILE: OnceLock<Option<Mutex<File>>> = OnceLock::new();
+static TRACE_BYTES: OnceLock<bool> = OnceLock::new();
+const HEALTH_LOG_MAX_BYTES: u64 = 1024 * 1024;
+
+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;
+    };
+    write_event(file, name, fields);
+}
+
+pub fn health_event(name: &str, fields: &[(&str, String)]) {
+    let Some(file) = HEALTH_FILE.get_or_init(open_health_file) else {
+        return;
+    };
+    write_event(file, name, fields);
+}
+
+pub fn default_health_log_path() -> PathBuf {
+    trace_root().join("health.log")
+}
+
+fn write_event(file: &Mutex<File>, name: &str, fields: &[(&str, String)]) {
+    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 open_health_file() -> Option<Mutex<File>> {
+    let path = health_log_path_from_env()?;
+    rotate_health_log_if_needed(&path);
+    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 health_log_path_from_env() -> Option<PathBuf> {
+    match std::env::var_os("DOSH_HEALTH_LOG") {
+        Some(raw) => {
+            let normalized = raw.to_string_lossy().to_ascii_lowercase();
+            if normalized.is_empty() || matches!(normalized.as_str(), "0" | "false" | "off") {
+                None
+            } else if matches!(normalized.as_str(), "1" | "true" | "on") {
+                Some(default_health_log_path())
+            } else {
+                Some(PathBuf::from(raw))
+            }
+        }
+        None => Some(default_health_log_path()),
+    }
+}
+
+fn rotate_health_log_if_needed(path: &Path) {
+    let Ok(metadata) = std::fs::metadata(path) else {
+        return;
+    };
+    if metadata.len() <= HEALTH_LOG_MAX_BYTES {
+        return;
+    }
+    let rotated = path.with_extension("log.1");
+    let _ = std::fs::remove_file(&rotated);
+    let _ = std::fs::rename(path, rotated);
+}
+
+fn default_trace_path() -> PathBuf {
+    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());
+    trace_root().join(format!("{}-{}.log", exe, std::process::id()))
+}
+
+fn trace_root() -> PathBuf {
+    dirs::cache_dir()
+        .unwrap_or_else(std::env::temp_dir)
+        .join("dosh")
+        .join("trace")
+}
+
+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();
+    let span = u32::from(TEST_UDP_PORT_END - TEST_UDP_PORT_START) + 1;
-    socket.local_addr().unwrap().port()
+    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();
+    for _ in TEST_PORT_START..=TEST_PORT_END {
-    socket.local_addr().unwrap().port()
+        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();
+    for _ in TEST_PORT_START..=TEST_PORT_END {
-    listener.local_addr().unwrap().port()
+        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 {
@@ -98,22 +122,71 @@ 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 {
+    start_server_with_trace(dir, config, None)
+}
+
+fn start_server_with_trace(
+    dir: &tempfile::TempDir,
+    config: &std::path::Path,
+    trace: Option<&Path>,
+) -> Child {
     let server = env!("CARGO_BIN_EXE_dosh-server");
-    let child = Command::new(server)
+    let mut command = Command::new(server);
+    command
         .arg("serve")
         .arg("--config")
         .arg(config)
         .env("HOME", dir.path())
         .stdout(Stdio::null())
-        .stderr(Stdio::null())
+        .stderr(Stdio::null());
-        .spawn()
+    if let Some(trace) = trace {
-        .unwrap();
+        command.env("DOSH_TRACE", trace);
+    }
+    let child = command.spawn().unwrap();
     thread::sleep(Duration::from_millis(500));
     child
 }
 
 fn attach_once(dir: &tempfile::TempDir, port: u16, cache: bool) -> std::process::Output {
+    attach_once_with_trace(dir, port, cache, None)
+}
+
+fn attach_once_with_trace(
+    dir: &tempfile::TempDir,
+    port: u16,
+    cache: bool,
+    trace: Option<&Path>,
+) -> std::process::Output {
     let client = env!("CARGO_BIN_EXE_dosh-client");
     let mut cmd = Command::new(client);
     cmd.arg("--local-auth")
@@ -128,6 +201,9 @@ fn attach_once(dir: &tempfile::TempDir, port: u16, cache: bool) -> std::process:
     if !cache {
         cmd.arg("--no-cache");
     }
+    if let Some(trace) = trace {
+        cmd.env("DOSH_TRACE", trace);
+    }
     cmd.output().unwrap()
 }
 
@@ -501,6 +577,75 @@ 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,
@@ -881,6 +1026,8 @@ fn native_file_copy_recursive_round_trip() {
     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)
@@ -986,6 +1133,14 @@ fn native_file_copy_recursive_round_trip() {
         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")
@@ -1009,6 +1164,191 @@ fn native_file_copy_recursive_round_trip() {
     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();
@@ -1247,7 +1587,9 @@ fn ticket_attach_after_server_restart_smoke() {
     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 server_trace = dir.path().join("server-trace.log");
+    let client_trace = dir.path().join("client-trace.log");
+    let mut server = start_server_with_trace(&dir, &config, Some(&server_trace));
     let first = attach_once(&dir, port, true);
     let _ = server.kill();
     let _ = server.wait();
@@ -1257,8 +1599,8 @@ fn ticket_attach_after_server_restart_smoke() {
         String::from_utf8_lossy(&first.stderr)
     );
 
-    let mut server = start_server(&dir, &config);
+    let mut server = start_server_with_trace(&dir, &config, Some(&server_trace));
-    let second = attach_once(&dir, port, true);
+    let second = attach_once_with_trace(&dir, port, true, Some(&client_trace));
     let _ = server.kill();
     let _ = server.wait();
     let stderr = String::from_utf8_lossy(&second.stderr);
@@ -1267,6 +1609,24 @@ fn ticket_attach_after_server_restart_smoke() {
         stderr.contains("udp_ticket_attach_ready"),
         "stderr={stderr}"
     );
+    let server_trace = fs::read_to_string(&server_trace).unwrap();
+    let client_trace = fs::read_to_string(&client_trace).unwrap();
+    assert!(
+        server_trace.contains("event=server.ticket_attach_start"),
+        "server trace={server_trace}"
+    );
+    assert!(
+        server_trace.contains("event=server.ticket_attach_ok"),
+        "server trace={server_trace}"
+    );
+    assert!(
+        client_trace.contains("event=client.ticket_attach_start"),
+        "client trace={client_trace}"
+    );
+    assert!(
+        client_trace.contains("event=client.ticket_attach_ok"),
+        "client trace={client_trace}"
+    );
 }
 
 #[test]
@@ -1363,18 +1723,10 @@ fn server_retransmits_unacked_output_frames() {
     );
 
     let mut seen = Vec::new();
-    let mut duplicate = None;
+    let deadline = std::time::Instant::now() + Duration::from_secs(4);
-    let deadline = std::time::Instant::now() + Duration::from_secs(3);
     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));
             }
         }
@@ -1383,9 +1735,18 @@ 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(),
+        max_same_output_seq >= 10,
-        "expected retransmitted same output seq, seen={seen:?}"
+        "expected retransmission to continue past the old 8-attempt ceiling, seen={seen:?}"
     );
 }
 
@@ -1639,6 +2000,110 @@ 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();
@@ -2385,6 +2850,9 @@ 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
 }
@@ -2420,6 +2888,45 @@ 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 {
@@ -2557,7 +3064,7 @@ 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();
@@ -2567,59 +3074,140 @@ 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 +1,101 @@
+#[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 complete_release_verifier_requires_both_macos_architectures() {
+    let verify = include_str!("../scripts/verify-release-artifacts.sh");
+    assert!(verify.contains("dosh-linux-x86_64.tar.gz"));
+    assert!(verify.contains("dosh-macos-aarch64.tar.gz"));
+    assert!(verify.contains("dosh-macos-x86_64.tar.gz"));
+    assert!(verify.contains("dosh-windows-x86_64.zip"));
+}
+
+#[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"
+        );
+    }
+}