Bind-mounted repos under /var/quire are owned by the host's git user;
baking a quire user with a different uid into the image triggered
git's safe.directory "dubious ownership" check. Setting the user at
docker run time keeps ownership aligned end-to-end.

Assisted-by: Claude Opus 4.7 via Claude Code

diff --git a/Dockerfile b/Dockerfile
index cd2a393..fc74769 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,14 +18,11 @@ RUN apt-get update \
 
 COPY --from=builder /usr/local/cargo/bin/quire /usr/local/bin/quire
 
-RUN groupadd --system quire \
-    && useradd --system --gid quire --create-home quire
+# Volume layout per PLAN.md. Ownership is set on the host; the container
+# runs as the host uid/gid passed via `docker exec --user`, so no user
+# is created in the image.
+RUN mkdir -p /var/quire/repos /var/quire/runs
 
-# Volume layout per PLAN.md.
-RUN mkdir -p /var/quire/repos /var/quire/runs \
-    && chown -R quire:quire /var/quire
-
-USER quire
 WORKDIR /var/quire
 
 ENTRYPOINT ["quire"]
diff --git a/docs/host/README.md b/docs/host/README.md
index 0e21244..c75d653 100644
--- a/docs/host/README.md
+++ b/docs/host/README.md
@@ -25,9 +25,18 @@ Reference configs for dispatching SSH connections into the quire container.
        sudo cp sshd_config /etc/ssh/sshd_config.d/quire.conf
        sudo systemctl reload sshd
 
-4. Start the quire container:
+4. Start the quire container, running as the host's `git` user so file
+   ownership on the bind-mounted `/var/quire` matches inside and out:
 
-       docker run -d --name quire-container quire
+       docker run -d --name quire-container \
+           --user "$(id -u git):$(id -g git)" \
+           -e HOME=/tmp \
+           -v /var/quire:/var/quire \
+           quire
+
+   In a compose file, the equivalent is `user: "${QUIRE_UID}:${QUIRE_GID}"`
+   with the values templated from `id -u git` / `id -g git` during host
+   setup.
 
 5. Test:
 
@@ -40,3 +49,10 @@ ForceCommand passes `$SSH_ORIGINAL_COMMAND` directly to the binary,
 which validates the git command against an allowlist (git-receive-pack,
 git-upload-pack, git-upload-archive) and sanitizes the repository path
 before exec'ing the git subprocess.
+
+The container image doesn't bake in a `quire` user — it runs as whatever
+uid/gid the host passes via `--user`. This avoids "dubious ownership"
+errors from git when the bind-mounted repo dir's host uid wouldn't
+otherwise match a container user. `HOME=/tmp` is set because the host
+uid has no `/etc/passwd` entry inside the container, and git needs a
+writable `HOME` for its config probing.
diff --git a/docs/host/sshd_config b/docs/host/sshd_config
index 096eb66..d32d3af 100644
--- a/docs/host/sshd_config
+++ b/docs/host/sshd_config
@@ -7,7 +7,7 @@
 
 Match User git
     AuthorizedKeysFile /home/git/.ssh/authorized_keys
-    ForceCommand docker exec -i quire-container quire exec "$SSH_ORIGINAL_COMMAND"
+    ForceCommand docker exec --interactive quire-container quire exec "$SSH_ORIGINAL_COMMAND"
     AllowTcpForwarding no
     AllowAgentForwarding no
     X11Forwarding no