Fix ssh/scp/sftp for containers running as a uid without passwd entry

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,13 @@
 All notable changes to CodeCraft. Versions follow [Semantic Versioning](https://semver.org/);
 until 1.0, minor versions may contain breaking changes.
 
+## [Unreleased]
+
+### Fixed
+
+- `ssh`, `scp` and `sftp` failed with "No user exists for uid 99" because the container runs as a uid
+  without passwd entry; the image now wraps them with nss_wrapper (also used by the key wrappers).
+
 ## [v202611-00033] – 2026-11-15
 
 ### Added

Dockerfile

@@ -85,7 +85,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential pkg-config libssl-dev cmake zlib1g-dev binutils-multiarch \
         chromium fonts-dejavu-core fonts-noto-color-emoji poppler-utils openmpt123 \
         openscad xvfb xauth \
-        openssh-client rsync mc \
+        openssh-client libnss-wrapper rsync mc \
     && rm -rf /var/lib/apt/lists/*
 # Language servers for diagnostics after edits (rust-analyzer/gopls/clangd can be
 # installed by agents: rustup component add rust-analyzer, go install …).
@@ -98,6 +98,10 @@ COPY --from=dockercli /docker /usr/local/bin/docker
 COPY server/ghidra /app/ghidra
 # git for agent shells: commits get the co-author trailer of the model (server.commit_trailer).
 COPY --chmod=755 docker/git-coauthor /usr/local/lib/codecraft/bin/git
+# ssh/scp/sftp also work when the container runs as a uid without passwd entry.
+COPY --chmod=755 docker/ssh-nss /usr/local/bin/ssh
+COPY --chmod=755 docker/ssh-nss /usr/local/bin/scp
+COPY --chmod=755 docker/ssh-nss /usr/local/bin/sftp
 COPY server/resources /app/resources
 # The agent's home lives on the data volume: tools it installs in user space
 # (pip --user, pipx, rustup, npm -g, downloaded binaries) survive rebuilds.

docker/ssh-nss

@@ -0,0 +1,13 @@
+#!/bin/sh
+# ssh, scp and sftp for containers that run as an arbitrary uid (docker-compose `user:`):
+# OpenSSH refuses to start without a passwd entry for the uid ("No user exists for uid N").
+# Without an entry, nss_wrapper provides one for this process; otherwise nothing changes.
+if ! getent passwd "$(id -u)" >/dev/null 2>&1; then
+  d=${TMPDIR:-/tmp}/codecraft-nss-$(id -u)
+  mkdir -p "$d" 2>/dev/null
+  printf 'codecraft:x:%s:%s:CodeCraft:%s:/bin/sh\n' "$(id -u)" "$(id -g)" "${HOME:-/}" > "$d/passwd"
+  printf 'codecraft:x:%s:\n' "$(id -g)" > "$d/group"
+  export NSS_WRAPPER_PASSWD="$d/passwd" NSS_WRAPPER_GROUP="$d/group"
+  export LD_PRELOAD="libnss_wrapper.so${LD_PRELOAD:+:$LD_PRELOAD}"
+fi
+exec "/usr/bin/$(basename "$0")" "$@"

server/src/sshkeys.rs

@@ -126,7 +126,10 @@ pub fn write_files(app: &App, user: &User, s: &SshSettings) -> Result<()> {
     chmod(&host_cfg, 0o600)?;
     for (bin, config) in [(bin_dir(&home), format!("'{}'", host_cfg.display())), (home.join(SANDBOX_BIN), "\"$HOME/.ssh/config-sandbox\"".to_string())] {
         std::fs::create_dir_all(&bin)?;
-        for (name, real) in [("ssh", "/usr/bin/ssh"), ("scp", "/usr/bin/scp"), ("sftp", "/usr/bin/sftp")] {
+        for name in ["ssh", "scp", "sftp"] {
+            // The image's /usr/local/bin wrappers cope with a uid without passwd entry.
+            let local = format!("/usr/local/bin/{name}");
+            let real = if Path::new(&local).exists() { local } else { format!("/usr/bin/{name}") };
             let p = bin.join(name);
             std::fs::write(&p, format!("#!/bin/sh\nexec {real} -F {config} \"$@\"\n"))?;
             chmod(&p, 0o755)?;

web/src/whatsnew.ts

@@ -3,6 +3,10 @@
  * under "unreleased"; scripts/release.sh renames the key to the release version.
  */
 export const WHATS_NEW: Record<string, { en: string[]; de: string[] }> = {
+  unreleased: {
+    en: ["ssh/scp/sftp now work in the container (fixes \"No user exists for uid\")"],
+    de: ["ssh/scp/sftp funktionieren jetzt im Container (behebt \"No user exists for uid\")"],
+  },
   "202611-00033": {
     en: ["SSH keys in Settings → Account: agents, terminal and git use them to reach other servers"],
     de: ["SSH-Schlüssel unter Einstellungen → Account: Agenten, Terminal und Git nutzen sie für den Zugriff auf andere Server"],