diff --git a/.github/workflows/release-canary.yml b/.github/workflows/release-canary.yml
index 239f49eced..f6e729fb40 100644
--- a/.github/workflows/release-canary.yml
+++ b/.github/workflows/release-canary.yml
@@ -195,6 +195,8 @@ jobs:
     name: Ubuntu Snap with system Docker
     if: ${{ github.event_name == 'workflow_dispatch' || github.event.workflow_run.conclusion == 'success' }}
     runs-on: ubuntu-latest
+    env:
+      OPENSHELL_INSTALL_METHOD: snap
     timeout-minutes: 20
     steps:
       - name: Install snapd
@@ -232,6 +234,9 @@ jobs:
           sudo snap connections openshell | grep -E '^docker +openshell:docker +:docker +'
           openshell --version
           sudo snap services openshell
+          sudo journalctl -b -u snap.openshell.gateway.service --no-pager |
+            grep -F "mTLS user authentication enabled"
+          openshell gateway list | grep -F "https://127.0.0.1:17670"
           openshell status
 
       - name: Create and exercise a sandbox
@@ -262,6 +267,8 @@ jobs:
     name: Ubuntu Snap Docker preflight
     if: ${{ github.event_name == 'workflow_dispatch' || github.event.workflow_run.conclusion == 'success' }}
     runs-on: ubuntu-latest
+    env:
+      OPENSHELL_INSTALL_METHOD: snap
     timeout-minutes: 20
     steps:
       - name: Install snapd
diff --git a/architecture/build.md b/architecture/build.md
index 43161b8c0c..639dde8ba8 100644
--- a/architecture/build.md
+++ b/architecture/build.md
@@ -324,24 +324,30 @@ for direct executable installation on every environment. Release Dev and
 Release Tag run Ubuntu conformance through the Debian package, while Fedora
 continues using direct executable installation until RPM coverage is available.
 The release canary separately exercises the public installer on Ubuntu. The
-OpenShell Snap requires a compatible, preinstalled non-Snap Docker daemon. Its
-positive canary uses system Docker; negative preflight coverage verifies that
-the installer rejects both missing Docker and the Docker Snap before installing
-OpenShell. Its Debian lane removes snapd before running the installer so Snap
-precedence cannot change the package under test.
-Explicit release tags and the `pre` alias bypass Snap selection and use the
-native Debian or RPM package path even when `snap` is available. The `pre` alias
+installer selects the OpenShell Snap only with `OPENSHELL_INSTALL_METHOD=snap`
+or when the Snap is already installed; otherwise it uses the native Debian or
+RPM package. The Snap requires a compatible, preinstalled non-Snap Docker
+daemon. Its positive canary uses system Docker; negative preflight coverage
+verifies that the installer rejects both missing Docker and the Docker Snap
+before installing OpenShell.
+Explicit release tags and the `pre` alias always use the native Debian or RPM
+package path. The `pre` alias
 checks matching Git tags in version order, then looks up the exact platform
 artifact and verifies the release run instead of listing every repository
 artifact.
 
 Snapd runs the gateway as a root-owned system service. Its generated client
-certificates reside in root-owned snap state and are unavailable to ordinary CLI
-users, so the Snap uses plaintext loopback transport and enables unauthenticated
-local users by default. Debian and RPM packages instead run systemd user services
-and use user-owned mTLS material. Bootstrap creates the default configuration
-only when it is missing. Sandbox-to-gateway sessions remain authenticated with
-gateway-minted JWTs.
+certificates reside in root-owned snap state. The installer copies the client
+bundle into the target user's private Snap state and registers the TLS endpoint;
+direct Snap installs require the same enrollment. The install and post-refresh
+hooks replace configs that explicitly enable plaintext or unauthenticated access
+with the secure default. Snap refreshes
+restart the gateway so the migrated config takes effect immediately.
+
+Debian and RPM packages instead run systemd user services with user-owned mTLS
+material. Sandbox-to-gateway sessions remain authenticated with gateway-minted
+JWTs.
+
 The Debian qualification profile keeps candidate-image overrides outside the
 operator-owned gateway configuration: it writes a harness-owned file under
 `/var/lib/openshell-qualification` and selects it through the packaged systemd
diff --git a/docs/about/installation.mdx b/docs/about/installation.mdx
index 350164c2a7..d41639cddc 100644
--- a/docs/about/installation.mdx
+++ b/docs/about/installation.mdx
@@ -38,7 +38,7 @@ curl -LsSf https://raw.githubusercontent.com/NVIDIA/OpenShell/main/install.sh |
   OPENSHELL_VERSION=pre sh
 ```
 
-The installer checks prerelease tags from newest to oldest, selects an unexpired artifact from a successful release run for the current platform, and downloads only that artifact. Installed packages keep the candidate's exact version, such as `0.1.0-pre.3`. Prerelease tags do not create entries on the GitHub Releases page. On Linux, prereleases and explicit release tags use Debian or RPM packages even if `snap` is installed.
+The installer checks prerelease tags from newest to oldest, selects an unexpired artifact from a successful release run for the current platform, and downloads only that artifact. Installed packages keep the candidate's exact version, such as `0.1.0-pre.3`. Prerelease tags do not create entries on the GitHub Releases page. On Linux, prereleases and explicit release tags use Debian or RPM packages.
 
 The rolling [`dev` release](https://github.com/NVIDIA/OpenShell/releases/tag/dev) does not require GitHub authentication:
 
@@ -86,7 +86,7 @@ The gateway reads `~/.config/openshell/gateway.toml` if it exists, otherwise the
 
 ## Linux
 
-The script uses the [Snap](#snap) package when `snap` is available. Otherwise, or when you set `OPENSHELL_VERSION` to a release tag, it installs a Debian package on Debian and Ubuntu or an RPM package on Fedora and RHEL. Linux packages require glibc 2.28 or newer.
+The script installs a Debian package on Debian and Ubuntu or an RPM package on Fedora and RHEL. Set `OPENSHELL_INSTALL_METHOD=snap` to install the [Snap](#snap) package instead; hosts that already have the OpenShell snap keep refreshing it. Linux packages require glibc 2.28 or newer.
 
 The gateway runs as a systemd user service at `https://127.0.0.1:17670` and reads `~/.config/openshell/gateway.toml`.
 
@@ -110,20 +110,22 @@ The snap requires Docker Engine installed from your distribution or Docker's pac
 sudo snap install openshell
 ```
 
-The snap does not migrate existing Debian, RPM, or Homebrew installs. Remove any existing installation first, then rerun the script with `OPENSHELL_ACK_BREAKING_UPGRADE=1`.
+The snap does not migrate existing Debian, RPM, or Homebrew installs. Remove any existing installation first, then rerun the script with `OPENSHELL_INSTALL_METHOD=snap OPENSHELL_ACK_BREAKING_UPGRADE=1`.
 
-The gateway runs as a system service at `http://127.0.0.1:17670` and reads `/var/snap/openshell/common/gateway.toml`.
-
-<Warning>
-The snap gateway allows unauthenticated access from the local host. Any local user or process can operate it. Do not expose it beyond the local host.
-</Warning>
-
-Snap refreshes do not restart the gateway, so active sandboxes keep running. Restart it to pick up a new version:
+The gateway runs as a system service at `https://127.0.0.1:17670` and reads `/var/snap/openshell/common/gateway.toml`. It requires a client certificate. The install script copies that certificate to the installing user's Snap state and registers the gateway automatically. If you installed with `sudo snap install openshell`, give each trusted user the certificate and register the gateway from that user's account:
 
 ```shell
-sudo systemctl restart snap.openshell.gateway
+d=~/snap/openshell/common/.local/state/openshell/tls
+mkdir -p -m 700 "$d" "$d/client"
+sudo install -o "$USER" -m 600 /var/snap/openshell/common/tls/ca.crt "$d/"
+sudo install -o "$USER" -m 600 -t "$d/client" \
+  /var/snap/openshell/common/tls/client/tls.crt /var/snap/openshell/common/tls/client/tls.key
+openshell gateway add https://127.0.0.1:17670 --local --name openshell
+openshell status
 ```
 
+Keep the client key private.
+
 To install a locally built snap, connect its interfaces manually:
 
 ```shell
diff --git a/install.sh b/install.sh
index 60bfd6f64c..83b7c479be 100755
--- a/install.sh
+++ b/install.sh
@@ -61,21 +61,22 @@ ENVIRONMENT VARIABLES:
     OPENSHELL_ACK_BREAKING_UPGRADE
                         Set to 1 only after backing up and cleaning up a
                         pre-v0.0.37 or non-snap installation.
+    OPENSHELL_INSTALL_METHOD
+                        Linux package to install: snap, deb, or rpm. Unset
+                        selects deb or rpm from the host package manager.
 
 NOTES:
     When OPENSHELL_VERSION is unset, this resolves the latest tagged release
     from ${GITHUB_URL}/releases/latest.
 
-    On Linux, the installer uses the OpenShell snap when the snap command is
-    available and OPENSHELL_VERSION is unset or dev. Snap installs use
-    latest/stable by default and latest/edge for dev. Explicit release tags
-    and prereleases use Debian or RPM packages. The OpenShell snap requires a
-    running Docker Engine installed from a system package or Docker's package
+    Linux installs the Debian package on amd64/arm64 or the RPM packages on
+    x86_64/aarch64, depending on the host package manager. Set
+    OPENSHELL_INSTALL_METHOD=snap to install the OpenShell snap instead; hosts
+    that already have the OpenShell snap keep refreshing it. Snap installs use
+    latest/stable by default and latest/edge for dev, and do not support
+    explicit release tags or prereleases. The OpenShell snap requires a running
+    Docker Engine installed from a system package or Docker's package
     repository. The Docker snap is not currently compatible with OpenShell.
-
-    For explicit versions or without snap, Linux installs the Debian package
-    on amd64/arm64 or the RPM packages on x86_64/aarch64, depending on the
-    host package manager.
     macOS installs the release Homebrew formula on Apple Silicon and starts a
     brew services-backed local gateway.
 EOF
@@ -658,9 +659,20 @@ local_gateway_endpoint() {
 }
 
 linux_package_method() {
+  case "${OPENSHELL_INSTALL_METHOD:-}" in
+    snap | deb | rpm)
+      echo "$OPENSHELL_INSTALL_METHOD"
+      return 0
+      ;;
+    '') ;;
+    *) error "unsupported OPENSHELL_INSTALL_METHOD=${OPENSHELL_INSTALL_METHOD}; use snap, deb, or rpm" ;;
+  esac
+
+  # Keep refreshing an existing snap install instead of adding a second
+  # gateway on the same port.
   case "${OPENSHELL_VERSION:-}" in
     '' | dev)
-      if has_cmd snap; then
+      if has_cmd snap && snap list openshell >/dev/null 2>&1; then
         echo "snap"
         return 0
       fi
@@ -1220,43 +1232,6 @@ openshell_snap_channel() {
   esac
 }
 
-ensure_snap_gateway_config() {
-  _config_file="${1:-/var/snap/openshell/common/gateway.toml}"
-
-  as_root sh -c '
-    set -eu
-    config_file=$1
-    if [ -e "$config_file" ] || [ -L "$config_file" ]; then
-      exit 0
-    fi
-
-    config_dir=${config_file%/*}
-    mkdir -p "$config_dir"
-    umask 077
-    temporary_file=$(mktemp "${config_file}.tmp.XXXXXX")
-    trap '\''rm -f "$temporary_file"'\'' 0 HUP INT TERM
-
-    cat >"$temporary_file" <<'\''EOF'\''
-[openshell]
-version = 2
-
-[openshell.gateway]
-
-[openshell.gateway.auth]
-allow_unauthenticated_users = true
-EOF
-
-    if ! ln "$temporary_file" "$config_file"; then
-      if [ -e "$config_file" ] || [ -L "$config_file" ]; then
-        exit 0
-      fi
-      exit 1
-    fi
-    rm -f "$temporary_file"
-    trap - 0 HUP INT TERM
-  ' sh "$_config_file"
-}
-
 wait_for_docker_daemon() {
   _timeout="${OPENSHELL_INSTALL_DOCKER_TIMEOUT:-30}"
   _elapsed=0
@@ -1280,9 +1255,39 @@ wait_for_docker_daemon() {
   error "Docker daemon did not become reachable within ${_timeout}s"
 }
 
+# Copy the snap gateway's client bundle into the target user's snap state
+# directory, where `openshell gateway add --local` imports it. Root only reads
+# the source files; the target user writes the copies into their own home.
+copy_snap_client_bundle() {
+  _src="${OPENSHELL_SNAP_TLS_DIR:-/var/snap/openshell/common/tls}"
+  _dst="${TARGET_HOME}/snap/openshell/common/.local/state/openshell/tls"
+
+  as_target_user mkdir -p "${_dst}/client"
+  as_target_user chmod 700 "$_dst" "${_dst}/client"
+  for _file in ca.crt client/tls.crt client/tls.key; do
+    as_root cat "${_src}/${_file}" |
+      as_target_user sh -c 'umask 077; cat >"$1"' sh "${_dst}/${_file}"
+    as_target_user chmod 600 "${_dst}/${_file}"
+  done
+}
+
+# Snap revisions that require mTLS ship the post-refresh hook that migrates
+# older plaintext configs.
+snap_gateway_uses_mtls() {
+  [ -e "${OPENSHELL_SNAP_DIR:-/snap/openshell/current}/meta/hooks/post-refresh" ]
+}
+
 register_snap_gateway() {
   _register_bin="${OPENSHELL_REGISTER_BIN:-/snap/bin/openshell}"
-  _endpoint="http://127.0.0.1:${LOCAL_GATEWAY_PORT}"
+
+  if snap_gateway_uses_mtls; then
+    _endpoint="https://127.0.0.1:${LOCAL_GATEWAY_PORT}"
+    info "copying the gateway client certificate for ${TARGET_USER}..."
+    copy_snap_client_bundle
+  else
+    _endpoint="http://127.0.0.1:${LOCAL_GATEWAY_PORT}"
+    warn "this OpenShell snap revision serves plaintext HTTP without client authentication; any local user can operate the gateway"
+  fi
 
   if _add_output="$(as_target_user "$_register_bin" gateway add "$_endpoint" --local --name openshell 2>&1)"; then
     [ -z "$_add_output" ] || print_gateway_add_output "$_add_output"
@@ -1304,15 +1309,28 @@ register_snap_gateway() {
   esac
 }
 
+# The mTLS gateway rejects TLS handshakes without a client certificate, so
+# probe it with the root-owned client bundle.
 wait_for_snap_gateway_listener() {
   _timeout="${OPENSHELL_INSTALL_GATEWAY_TIMEOUT:-30}"
   _elapsed=0
   _last_output=""
-  _probe_url="http://127.0.0.1:${LOCAL_GATEWAY_PORT}/"
+  _tls_dir="${OPENSHELL_SNAP_TLS_DIR:-/var/snap/openshell/common/tls}"
+
+  if snap_gateway_uses_mtls; then
+    _probe_url="https://127.0.0.1:${LOCAL_GATEWAY_PORT}/"
+    _probe_as=as_root
+    set -- --cacert "${_tls_dir}/ca.crt" \
+      --cert "${_tls_dir}/client/tls.crt" --key "${_tls_dir}/client/tls.key"
+  else
+    _probe_url="http://127.0.0.1:${LOCAL_GATEWAY_PORT}/"
+    _probe_as=""
+    set --
+  fi
 
   info "waiting for local gateway listener to become reachable..."
   while [ "$_elapsed" -lt "$_timeout" ]; do
-    if _last_output="$(curl -sS --max-time 2 -o /dev/null "$_probe_url" 2>&1)"; then
+    if _last_output="$($_probe_as curl -sS --max-time 2 "$@" -o /dev/null "$_probe_url" 2>&1)"; then
       info "local gateway listener is reachable"
       return 0
     fi
@@ -1350,13 +1368,12 @@ Install Docker Engine from a system package or Docker's package repository, then
     as_root snap install openshell --channel="$_channel"
   fi
 
-  ensure_snap_gateway_config
   as_root snap restart openshell.gateway
 
   info "installed OpenShell snap from ${_channel}"
+  wait_for_snap_gateway_listener
   info "registering local gateway as ${TARGET_USER}..."
   register_snap_gateway
-  wait_for_snap_gateway_listener
   OPENSHELL_REGISTER_BIN="/snap/bin/openshell"
   wait_for_local_gateway_status
 }
diff --git a/nix/test-guest/scripts/snap-gateway-repro.sh b/nix/test-guest/scripts/snap-gateway-repro.sh
index d92800b523..43b7f3949c 100755
--- a/nix/test-guest/scripts/snap-gateway-repro.sh
+++ b/nix/test-guest/scripts/snap-gateway-repro.sh
@@ -99,7 +99,7 @@ for attempt in $(seq 1 "${attempts}"); do
 	echo "==> install.sh Snap ${mode} reproduction attempt ${attempt}/${attempts}"
 	if [ "${mode}" != system-docker ]; then
 		output=$(mktemp)
-		if OPENSHELL_VERSION=dev sh "${install_script}" >"${output}" 2>&1; then
+		if OPENSHELL_INSTALL_METHOD=snap OPENSHELL_VERSION=dev sh "${install_script}" >"${output}" 2>&1; then
 			echo "install.sh unexpectedly succeeded in ${mode} mode" >&2
 			cat "${output}" >&2
 			rm -f "${output}"
@@ -127,7 +127,7 @@ for attempt in $(seq 1 "${attempts}"); do
 	fi
 
 	sandbox="snap-${attempt}-$$"
-	if ! OPENSHELL_VERSION=dev sh "${install_script}" ||
+	if ! OPENSHELL_INSTALL_METHOD=snap OPENSHELL_VERSION=dev sh "${install_script}" ||
 		! sudo snap list openshell >/dev/null ||
 		! snap info openshell | grep -Eq '^tracking: +latest/edge$' ||
 		! docker_is_ready ||
diff --git a/python/openshell/release_formula_test.py b/python/openshell/release_formula_test.py
index 61fff150ac..4db21b0951 100644
--- a/python/openshell/release_formula_test.py
+++ b/python/openshell/release_formula_test.py
@@ -155,7 +155,11 @@ def test_snap_wrapper_uses_optional_gateway_config_without_generating_toml() ->
         'export OPENSHELL_DB_URL="${OPENSHELL_DB_URL:-sqlite:${SNAP_COMMON}/gateway.db?mode=rwc}"'
         in wrapper
     )
-    assert 'export OPENSHELL_DISABLE_TLS="${OPENSHELL_DISABLE_TLS:-true}"' in wrapper
+    assert "OPENSHELL_DISABLE_TLS" not in wrapper
+    assert (
+        'export OPENSHELL_LOCAL_TLS_DIR="${OPENSHELL_LOCAL_TLS_DIR:-${SNAP_COMMON}/tls}"'
+        in wrapper
+    )
     assert (
         'exec "${SNAP}/bin/openshell-gateway" --config "$CANONICAL_CONFIG_FILE" "$@"'
         in wrapper
diff --git a/skills/debug-openshell-cluster/SKILL.md b/skills/debug-openshell-cluster/SKILL.md
index 8e865f13ec..6ccff2f2f8 100644
--- a/skills/debug-openshell-cluster/SKILL.md
+++ b/skills/debug-openshell-cluster/SKILL.md
@@ -72,6 +72,7 @@ Common findings:
 - `No active gateway`: register one with `openshell gateway add <endpoint>`.
 - Connection refused: gateway process is not running, service exposure is wrong, or a port-forward/proxy is not active.
 - TLS/certificate errors: the endpoint scheme or trust chain is wrong, a local mTLS bundle does not match the gateway CA, or TLS termination does not match the gateway listener.
+- A Snap refresh restarts the gateway with its migrated mTLS config. The secure Snap gateway uses `https://127.0.0.1:17670` and requires a client bundle in the user's Snap state. Refresh replaces insecure configs without keeping a copy; follow the published Snap installation steps to re-register an old HTTP client.
 - `Unauthenticated` from an edge or OIDC gateway: refresh stored credentials with `openshell gateway login [name]`, then retry. Use `gateway logout` only when intentionally clearing local credentials.
 - A direct development endpoint with a private or self-signed certificate can be isolated with `--gateway-endpoint <url> --gateway-insecure`; do not persist or recommend insecure verification for shared gateways.
 
diff --git a/snap/hooks/install b/snap/hooks/install
index c5fb3baf87..78efeefdf8 100755
--- a/snap/hooks/install
+++ b/snap/hooks/install
@@ -2,10 +2,22 @@
 # SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
+# Create the mTLS default and replace insecure configs on refresh.
+
 set -eu
 
 config_file="${SNAP_COMMON}/gateway.toml"
-if [ -e "$config_file" ] || [ -L "$config_file" ]; then
+insecure='^[[:space:]]*(allow_unauthenticated_users|disable_tls)[[:space:]]*=[[:space:]]*true([[:space:]#]|$)'
+
+# Keep secure operator configs, symlinks, and directories. Replace a config
+# that explicitly allows plaintext or anonymous access, even if it has other
+# edits.
+if [ -L "$config_file" ]; then
+	exit 0
+elif [ -f "$config_file" ]; then
+	grep -Eq "$insecure" "$config_file" || exit 0
+	echo "openshell: replacing insecure gateway config with the mTLS default" >&2
+elif [ -e "$config_file" ]; then
 	exit 0
 fi
 
@@ -13,24 +25,11 @@ mkdir -p "$SNAP_COMMON"
 umask 077
 temporary_file=$(mktemp "${config_file}.tmp.XXXXXX")
 trap 'rm -f "$temporary_file"' 0 HUP INT TERM
-
-cat >"$temporary_file" <<'EOF'
+cat >"$temporary_file" <<'CONFIG'
 [openshell]
 version = 2
 
 [openshell.gateway]
-
-[openshell.gateway.auth]
-allow_unauthenticated_users = true
-EOF
-
-# A hard link publishes the config atomically without replacing a path created
-# concurrently. SNAP_COMMON and the temporary file are on the same filesystem.
-if ! ln "$temporary_file" "$config_file"; then
-	if [ -e "$config_file" ] || [ -L "$config_file" ]; then
-		exit 0
-	fi
-	exit 1
-fi
-rm -f "$temporary_file"
+CONFIG
+mv -f "$temporary_file" "$config_file"
 trap - 0 HUP INT TERM
diff --git a/snap/hooks/post-refresh b/snap/hooks/post-refresh
new file mode 100755
index 0000000000..28eb20373d
--- /dev/null
+++ b/snap/hooks/post-refresh
@@ -0,0 +1,12 @@
+#!/bin/sh
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Replace insecure gateway configs on refresh, then restart the gateway so the
+# new config takes effect even when the previous revision used
+# refresh-mode: endure and kept its plaintext gateway running.
+
+set -eu
+
+"${SNAP}/meta/hooks/install"
+snapctl restart "${SNAP_INSTANCE_NAME}.gateway"
diff --git a/snapcraft.yaml b/snapcraft.yaml
index 4c602620cf..6c943c1387 100644
--- a/snapcraft.yaml
+++ b/snapcraft.yaml
@@ -29,18 +29,18 @@ description: |
          sudo systemctl reset-failed snap.openshell.gateway.service
          sudo snap restart openshell.gateway
 
-    2. Verify the gateway and register it locally:
+    2. Give your user the gateway client certificate and register the gateway.
+       The gateway requires mTLS; only users holding this certificate can use
+       it, so copy it only for trusted users:
 
          snap services openshell.gateway
+         d=~/snap/openshell/common/.local/state/openshell/tls
+         mkdir -p -m 700 "$d" "$d/client"
+         sudo install -o "$USER" -m 600 /var/snap/openshell/common/tls/ca.crt "$d/"
+         sudo install -o "$USER" -m 600 -t "$d/client" \
+           /var/snap/openshell/common/tls/client/tls.crt /var/snap/openshell/common/tls/client/tls.key
+         openshell gateway add https://127.0.0.1:17670 --local --name openshell
          openshell status
-         openshell gateway add http://127.0.0.1:17670 --local --name openshell-gateway
-
-    After a snap refresh, restart the gateway to pick up the new revision:
-
-         sudo snap restart openshell.gateway
-
-    Restarting the gateway will interrupt active sandbox sessions. The gateway
-    is not restarted automatically to avoid disconnecting running sandboxes.
 
 base: core24
 grade: stable
@@ -88,17 +88,16 @@ apps:
   gateway:
     command: bin/openshell-gateway-wrapper
     daemon: simple
-    # refresh-mode: endure prevents snapd from restarting the gateway daemon
-    # during snap refreshes, which would kill active sandbox sessions.
-    # Operators must manually restart the service after a refresh if needed.
-    refresh-mode: endure
-    # Snapd runs this daemon as root, so ordinary CLI users cannot read the
-    # client certificate generated in root-owned snap state. The wrapper sets
-    # OPENSHELL_DISABLE_TLS=true for the loopback-only listener and uses
-    # $SNAP_COMMON/gateway.db. Before startup it bootstraps package-managed
-    # credentials and validates the selected operator-provided config without
-    # creating or rewriting it. A nonempty OPENSHELL_GATEWAY_CONFIG takes
-    # precedence over gateway.toml.
+    # Refresh must activate the migrated mTLS config immediately. This
+    # interrupts active sandbox sessions.
+    refresh-mode: restart
+    # Snapd runs this daemon as root. The wrapper serves TLS from the bundle
+    # generated in $SNAP_COMMON/tls, and the default config requires client
+    # certificates; the installer copies the client bundle to the target
+    # user. The wrapper uses $SNAP_COMMON/gateway.db. Before startup it
+    # bootstraps package-managed credentials and validates the selected
+    # operator-provided config without creating or rewriting it. A nonempty
+    # OPENSHELL_GATEWAY_CONFIG takes precedence over gateway.toml.
     environment:
       XDG_DATA_HOME: "$SNAP_COMMON"
       XDG_RUNTIME_DIR: "$SNAP_COMMON"
diff --git a/tasks/scripts/snap-gateway-wrapper.sh b/tasks/scripts/snap-gateway-wrapper.sh
index 4a98962559..a047cf72e3 100755
--- a/tasks/scripts/snap-gateway-wrapper.sh
+++ b/tasks/scripts/snap-gateway-wrapper.sh
@@ -3,16 +3,16 @@
 # SPDX-License-Identifier: Apache-2.0
 
 # Snap wrapper for openshell-gateway. Sets snap-specific defaults:
-#   - OPENSHELL_DB_URL  -> sqlite:$SNAP_COMMON/gateway.db (overridable)
-#   - OPENSHELL_DISABLE_TLS -> true
-# It bootstraps package-managed credentials and validates, but never creates or
-# rewrites, an operator-provided config before starting the gateway.
+#   - OPENSHELL_DB_URL        -> sqlite:$SNAP_COMMON/gateway.db (overridable)
+#   - OPENSHELL_LOCAL_TLS_DIR -> $SNAP_COMMON/tls (overridable)
+# The gateway serves TLS from the generated bundle and requires client
+# certificates. It bootstraps package-managed credentials and validates, but
+# never creates or rewrites, an operator-provided config before starting.
 
 set -eu
 
 CANONICAL_CONFIG_FILE="${SNAP_COMMON}/gateway.toml"
 export OPENSHELL_DB_URL="${OPENSHELL_DB_URL:-sqlite:${SNAP_COMMON}/gateway.db?mode=rwc}"
-export OPENSHELL_DISABLE_TLS="${OPENSHELL_DISABLE_TLS:-true}"
 export OPENSHELL_LOCAL_TLS_DIR="${OPENSHELL_LOCAL_TLS_DIR:-${SNAP_COMMON}/tls}"
 
 # Mirror clap's CLI-over-environment precedence so preflight always inspects
@@ -64,9 +64,9 @@ if [ "$expect_config_path" = true ] || { [ "$config_seen" = true ] && [ -z "$cli
     exit 2
 fi
 
-# Docker sandboxes require gateway-minted, launch-scoped credentials for the
-# supervisor. Generate the local JWT bundle alongside the otherwise-unused TLS
-# material; generate-certs is idempotent and preserves an existing bundle.
+# Generate the local TLS bundle and the JWT bundle used for launch-scoped
+# supervisor credentials; generate-certs is idempotent and preserves an
+# existing bundle.
 "${SNAP}/bin/openshell-gateway" generate-certs \
     --output-dir "$OPENSHELL_LOCAL_TLS_DIR" \
     --server-san host.openshell.internal
diff --git a/tasks/scripts/test-install-sh.sh b/tasks/scripts/test-install-sh.sh
index 8cc6102148..286fa3f1ff 100755
--- a/tasks/scripts/test-install-sh.sh
+++ b/tasks/scripts/test-install-sh.sh
@@ -100,25 +100,30 @@ assert_glibc_preflight_fails \
   "OpenShell Linux packages require glibc >= 2.28; detected musl or unsupported libc." \
   setup_ldd_musl
 
+# snap_state: 0 = no snap command, 1 = snap command only,
+# installed = the OpenShell snap is already installed.
 assert_linux_package_method() {
   local name=$1
-  local requested_version=$2
-  local snap_present=$3
-  local dpkg_present=$4
-  local rpm_present=$5
-  local expected=$6
+  local install_method=$2
+  local requested_version=$3
+  local snap_state=$4
+  local dpkg_present=$5
+  local rpm_present=$6
+  local expected=$7
   local actual
 
   actual="$(
+    export OPENSHELL_INSTALL_METHOD="$install_method"
     export OPENSHELL_VERSION="$requested_version"
     has_cmd() {
       case "$1" in
-        snap) [ "$snap_present" = "1" ] ;;
+        snap) [ "$snap_state" != "0" ] ;;
         dpkg) [ "$dpkg_present" = "1" ] ;;
         rpm) [ "$rpm_present" = "1" ] ;;
         *) return 1 ;;
       esac
     }
+    snap() { [ "$*" = "list openshell" ] && [ "$snap_state" = "installed" ]; }
     linux_package_method
   )"
   if [ "$actual" != "$expected" ]; then
@@ -127,16 +132,30 @@ assert_linux_package_method() {
   fi
 }
 
-assert_linux_package_method "snap takes precedence over deb and rpm" "" 1 1 1 snap
-assert_linux_package_method "dev uses snap" dev 1 1 1 snap
-assert_linux_package_method "pre uses deb despite snap" pre 1 1 1 deb
-assert_linux_package_method "numbered prerelease uses deb despite snap" v0.1.0-pre.3 1 1 1 deb
-assert_linux_package_method "pre uses rpm despite snap" pre 1 0 1 rpm
-assert_linux_package_method "pinned stable uses deb despite snap" v1.2.3 1 1 1 deb
-assert_linux_package_method "pinned stable uses rpm despite snap" v1.2.3 1 0 1 rpm
-assert_linux_package_method "deb is selected without snap" "" 0 1 1 deb
-assert_linux_package_method "dev uses deb without snap" dev 0 1 1 deb
-assert_linux_package_method "rpm is selected without snap or deb" "" 0 0 1 rpm
+assert_linux_package_method "deb is the default despite snap" "" "" 1 1 1 deb
+assert_linux_package_method "rpm is the default despite snap" "" "" 1 0 1 rpm
+assert_linux_package_method "dev uses deb despite snap" "" dev 1 1 1 deb
+assert_linux_package_method "snap is opt-in" snap "" 1 1 1 snap
+assert_linux_package_method "snap opt-in with dev" snap dev 1 1 1 snap
+assert_linux_package_method "explicit deb" deb "" installed 0 1 deb
+assert_linux_package_method "explicit rpm" rpm "" 1 1 1 rpm
+assert_linux_package_method "existing snap install keeps refreshing" "" "" installed 1 1 snap
+assert_linux_package_method "existing snap install keeps refreshing dev" "" dev installed 1 1 snap
+assert_linux_package_method "pre uses deb despite existing snap" "" pre installed 1 1 deb
+assert_linux_package_method "numbered prerelease uses deb despite existing snap" "" v0.1.0-pre.3 installed 1 1 deb
+assert_linux_package_method "pinned stable uses rpm despite existing snap" "" v1.2.3 installed 0 1 rpm
+assert_linux_package_method "deb is selected without snap" "" "" 0 1 1 deb
+assert_linux_package_method "rpm is selected without snap or deb" "" "" 0 0 1 rpm
+
+if (OPENSHELL_INSTALL_METHOD=flatpak linux_package_method) >"$out" 2>"$err"; then
+  echo "FAIL: unsupported OPENSHELL_INSTALL_METHOD should be rejected" >&2
+  exit 1
+fi
+if ! grep -Fq "unsupported OPENSHELL_INSTALL_METHOD=flatpak" "$err"; then
+  echo "FAIL: unsupported OPENSHELL_INSTALL_METHOD was not explained" >&2
+  cat "$err" >&2
+  exit 1
+fi
 
 if ! (
   find_existing_native_openshell_bin() { return 1; }
@@ -269,7 +288,6 @@ assert_snap_install_flow() {
     as_root() { printf 'root:%s\n' "$*"; }
     set_linux_target_runtime_dir() { :; }
     wait_for_docker_daemon() { printf '%s\n' "wait:docker"; }
-    ensure_snap_gateway_config() { printf '%s\n' "ensure:gateway-config"; }
     register_snap_gateway() { printf '%s\n' "register:gateway"; }
     wait_for_snap_gateway_listener() { printf '%s\n' "wait:gateway-listener"; }
     wait_for_local_gateway_status() { printf '%s\n' "wait:gateway-status"; }
@@ -293,10 +311,9 @@ assert_snap_install_flow \
   1 0 "" \
   "wait:docker
 root:snap install openshell --channel=latest/stable
-ensure:gateway-config
 root:snap restart openshell.gateway
-register:gateway
 wait:gateway-listener
+register:gateway
 wait:gateway-status"
 
 assert_snap_install_flow \
@@ -304,10 +321,9 @@ assert_snap_install_flow \
   1 1 "" \
   "wait:docker
 root:snap refresh openshell --channel=latest/stable
-ensure:gateway-config
 root:snap restart openshell.gateway
-register:gateway
 wait:gateway-listener
+register:gateway
 wait:gateway-status"
 
 assert_snap_install_rejected() {
@@ -363,34 +379,6 @@ assert_snap_install_rejected \
   1 1 \
   "the Docker snap is not currently compatible with OpenShell"
 
-snap_config_dir="${tmpdir}/snap-config"
-snap_config="${snap_config_dir}/gateway.toml"
-if ! (as_root() { "$@"; }; ensure_snap_gateway_config "$snap_config"); then
-  echo "FAIL: Snap gateway config bootstrap should create a missing config" >&2
-  exit 1
-fi
-if ! grep -Fq 'allow_unauthenticated_users = true' "$snap_config"; then
-  echo "FAIL: Snap gateway config must permit the plaintext local CLI" >&2
-  exit 1
-fi
-if [[ -z $(find "$snap_config" -perm 600) ]]; then
-  echo "FAIL: Snap gateway config must be mode 0600" >&2
-  exit 1
-fi
-
-printf '\noperator setting = true\n' >>"$snap_config"
-cp "$snap_config" "${tmpdir}/snap-config-before"
-(as_root() { "$@"; }; ensure_snap_gateway_config "$snap_config")
-cmp -s "${tmpdir}/snap-config-before" "$snap_config"
-
-broken_config="${tmpdir}/broken-gateway.toml"
-ln -s "${tmpdir}/missing-gateway.toml" "$broken_config"
-(as_root() { "$@"; }; ensure_snap_gateway_config "$broken_config")
-if [[ $(readlink "$broken_config") != "${tmpdir}/missing-gateway.toml" ]]; then
-  echo "FAIL: Snap gateway config bootstrap replaced a broken operator symlink" >&2
-  exit 1
-fi
-
 attempts_file="${tmpdir}/docker-attempts"
 root_probes_file="${tmpdir}/docker-root-probes"
 printf '0\n' >"$attempts_file"
@@ -450,7 +438,11 @@ registration_calls_file="${tmpdir}/registration-calls"
 : >"$registration_calls_file"
 if ! (
   as_target_user() { printf 'target:%s\n' "$*" >>"$registration_calls_file"; }
+  copy_snap_client_bundle() { printf 'copy:client-bundle\n' >>"$registration_calls_file"; }
   print_gateway_add_output() { :; }
+  info() { :; }
+  TARGET_USER=test-user
+  snap_gateway_uses_mtls() { return 0; }
   register_snap_gateway
 ) >"$out" 2>"$err"; then
   echo "FAIL: Snap gateway registration should succeed" >&2
@@ -458,11 +450,92 @@ if ! (
   exit 1
 fi
 registration_calls="$(cat "$registration_calls_file")"
+if [ "$registration_calls" != "copy:client-bundle
+target:/snap/bin/openshell gateway add https://127.0.0.1:17670 --local --name openshell" ]; then
+  echo "FAIL: mTLS Snap gateway registration must copy the client bundle and use HTTPS" >&2
+  printf '%s\n' "$registration_calls" >&2
+  exit 1
+fi
+
+: >"$registration_calls_file"
+if ! (
+  as_target_user() { printf 'target:%s\n' "$*" >>"$registration_calls_file"; }
+  copy_snap_client_bundle() { printf 'copy:client-bundle\n' >>"$registration_calls_file"; }
+  print_gateway_add_output() { :; }
+  snap_gateway_uses_mtls() { return 1; }
+  register_snap_gateway
+) >"$out" 2>"$err"; then
+  echo "FAIL: legacy plaintext Snap gateway registration should succeed" >&2
+  cat "$err" >&2 || true
+  exit 1
+fi
+registration_calls="$(cat "$registration_calls_file")"
 if [ "$registration_calls" != "target:/snap/bin/openshell gateway add http://127.0.0.1:17670 --local --name openshell" ]; then
-  echo "FAIL: Snap gateway registration must use the Snap CLI as the target user" >&2
+  echo "FAIL: legacy Snap gateway registration must use HTTP without copying certificates" >&2
   printf '%s\n' "$registration_calls" >&2
   exit 1
 fi
+if ! grep -Fq "without client authentication" "$err"; then
+  echo "FAIL: legacy Snap gateway registration must warn about unauthenticated access" >&2
+  exit 1
+fi
+
+assert_snap_listener_probe() {
+  local name=$1
+  local uses_mtls=$2
+  local expected=$3
+  local actual
+
+  actual="$(
+    as_root() { printf 'root:'; "$@"; }
+    curl() { printf '%s\n' "$*"; }
+    snap_gateway_uses_mtls() { [ "$uses_mtls" = "1" ]; }
+    info() { :; }
+    OPENSHELL_SNAP_TLS_DIR=/tls
+    wait_for_snap_gateway_listener >/dev/null
+    printf '%s\n' "$_last_output"
+  )"
+  if [ "$actual" != "$expected" ]; then
+    echo "FAIL: ${name}: expected ${expected}, got ${actual}" >&2
+    exit 1
+  fi
+}
+
+assert_snap_listener_probe "mTLS snap probes HTTPS with the client bundle as root" 1 \
+  "root:-sS --max-time 2 --cacert /tls/ca.crt --cert /tls/client/tls.crt --key /tls/client/tls.key -o /dev/null https://127.0.0.1:17670/"
+assert_snap_listener_probe "legacy snap probes plaintext HTTP" 0 \
+  "-sS --max-time 2 -o /dev/null http://127.0.0.1:17670/"
+
+snap_tls_src="${tmpdir}/snap-tls"
+mkdir -p "${snap_tls_src}/client"
+printf 'ca\n' >"${snap_tls_src}/ca.crt"
+printf 'cert\n' >"${snap_tls_src}/client/tls.crt"
+printf 'key\n' >"${snap_tls_src}/client/tls.key"
+snap_user_home="${tmpdir}/snap-user-home"
+mkdir -p "${snap_user_home}/snap/openshell/common/.local/state/openshell/tls/client"
+printf 'old key\n' >"${snap_user_home}/snap/openshell/common/.local/state/openshell/tls/client/tls.key"
+chmod 644 "${snap_user_home}/snap/openshell/common/.local/state/openshell/tls/client/tls.key"
+(
+  as_root() { "$@"; }
+  as_target_user() { "$@"; }
+  TARGET_HOME="$snap_user_home"
+  OPENSHELL_SNAP_TLS_DIR="$snap_tls_src" copy_snap_client_bundle
+)
+snap_user_tls="${snap_user_home}/snap/openshell/common/.local/state/openshell/tls"
+for file in ca.crt client/tls.crt client/tls.key; do
+  if ! cmp -s "${snap_tls_src}/${file}" "${snap_user_tls}/${file}"; then
+    echo "FAIL: Snap client bundle copy missing ${file}" >&2
+    exit 1
+  fi
+  if [[ -z $(find "${snap_user_tls}/${file}" -perm 600) ]]; then
+    echo "FAIL: Snap client bundle ${file} must be mode 0600" >&2
+    exit 1
+  fi
+done
+if [[ -z $(find "$snap_user_tls" -maxdepth 0 -perm 700) ]]; then
+  echo "FAIL: Snap client bundle directory must be mode 0700" >&2
+  exit 1
+fi
 
 if [ "$(PLATFORM=darwin local_gateway_endpoint)" != "https://localhost:17670" ]; then
   echo "FAIL: macOS local gateway endpoint must use a TLS-compatible loopback hostname" >&2
diff --git a/tasks/scripts/test-packaging-assets.sh b/tasks/scripts/test-packaging-assets.sh
index 345a0e3964..04f69b08be 100755
--- a/tasks/scripts/test-packaging-assets.sh
+++ b/tasks/scripts/test-packaging-assets.sh
@@ -123,7 +123,14 @@ if [[ ! -x "$snap_install_hook" ]]; then
   echo "FAIL: Snap install hook must be executable" >&2
   exit 1
 fi
-assert_contains "$snap_install_hook" 'allow_unauthenticated_users = true'
+assert_not_contains "$snap_install_hook" 'compute_driver'
+assert_not_contains "$snap_install_hook" 'allow_unauthenticated_users = true'
+assert_contains "$snapcraft" 'refresh-mode: restart'
+if [[ ! -x "$(dirname "$snap_install_hook")/post-refresh" ]]; then
+  echo "FAIL: Snap post-refresh hook must be executable" >&2
+  exit 1
+fi
+assert_not_contains "$ROOT/tasks/scripts/snap-gateway-wrapper.sh" 'OPENSHELL_DISABLE_TLS'
 bash "$ROOT/tasks/scripts/test-snap-install-hook.sh" "$snap_install_hook"
 assert_not_contains "$snap_install_docs" "snap connect openshell:home"
 assert_not_contains "$snap_install_docs" "snap connect openshell:network"
@@ -132,7 +139,7 @@ assert_contains "$snap_install_docs" "snap connect openshell:docker :docker"
 assert_contains "$snap_canary" "install.sh | sh"
 assert_contains "$snap_canary" "ubuntu-snap-system-docker:"
 assert_contains "$snap_canary" "ubuntu-snap-docker-preflight:"
-assert_contains "$snap_repro" 'OPENSHELL_VERSION=dev sh "${install_script}"'
+assert_contains "$snap_repro" 'OPENSHELL_INSTALL_METHOD=snap OPENSHELL_VERSION=dev sh "${install_script}"'
 assert_contains "$snap_repro" "system-docker"
 assert_contains "$snap_repro" "missing-docker"
 assert_contains "$snap_repro" "docker-snap"
diff --git a/tasks/scripts/test-snap-gateway-wrapper.sh b/tasks/scripts/test-snap-gateway-wrapper.sh
index a14076b121..691a1e7628 100755
--- a/tasks/scripts/test-snap-gateway-wrapper.sh
+++ b/tasks/scripts/test-snap-gateway-wrapper.sh
@@ -82,9 +82,9 @@ cp "$override" "$work/override-before"
 : >"$log"
 run_wrapper "$override"
 assert_log "config preflight -- --trace
-env:$override|sqlite:$common/gateway.db?mode=rwc|true
+env:$override|sqlite:$common/gateway.db?mode=rwc|
 --trace
-env:$override|sqlite:$common/gateway.db?mode=rwc|true"
+env:$override|sqlite:$common/gateway.db?mode=rwc|"
 cmp -s "$work/override-before" "$override"
 
 cli_config="$work/cli.toml"
@@ -98,9 +98,9 @@ env \
   FAKE_GATEWAY_LOG="$log" \
   "$wrapper" --trace --config "$cli_config"
 assert_log "config preflight -- --trace --config $cli_config
-env:$override|sqlite:$common/gateway.db?mode=rwc|true
+env:$override|sqlite:$common/gateway.db?mode=rwc|
 --trace --config $cli_config
-env:$override|sqlite:$common/gateway.db?mode=rwc|true"
+env:$override|sqlite:$common/gateway.db?mode=rwc|"
 cmp -s "$work/cli-before" "$cli_config"
 
 : >"$log"
@@ -115,7 +115,7 @@ if env \
   exit 1
 fi
 assert_log "config preflight -- --config=$cli_config
-env:$override|sqlite:$common/gateway.db?mode=rwc|true"
+env:$override|sqlite:$common/gateway.db?mode=rwc|"
 cmp -s "$work/cli-before" "$cli_config"
 
 : >"$log"
@@ -130,7 +130,7 @@ if env \
   exit 1
 fi
 assert_log "config preflight -- --grpc-rate-limit-requests 10
-env:$override|sqlite:$common/gateway.db?mode=rwc|true"
+env:$override|sqlite:$common/gateway.db?mode=rwc|"
 
 for invalid_selector in terminator nested-config; do
   : >"$log"
@@ -162,9 +162,9 @@ env \
   FAKE_GATEWAY_LOG="$log" \
   "$wrapper" --config=--dash-leading
 assert_log "config preflight -- --config=--dash-leading
-env:$override|sqlite:$common/gateway.db?mode=rwc|true
+env:$override|sqlite:$common/gateway.db?mode=rwc|
 --config=--dash-leading
-env:$override|sqlite:$common/gateway.db?mode=rwc|true"
+env:$override|sqlite:$common/gateway.db?mode=rwc|"
 
 canonical="$common/gateway.toml"
 printf 'valid schema-v2\n' >"$canonical"
@@ -172,18 +172,18 @@ cp "$canonical" "$work/canonical-before"
 : >"$log"
 run_wrapper unset
 assert_log "config preflight -- --config $canonical --trace
-env:|sqlite:$common/gateway.db?mode=rwc|true
+env:|sqlite:$common/gateway.db?mode=rwc|
 --config $canonical --trace
-env:|sqlite:$common/gateway.db?mode=rwc|true"
+env:|sqlite:$common/gateway.db?mode=rwc|"
 cmp -s "$work/canonical-before" "$canonical"
 
 rm "$canonical"
 : >"$log"
 run_wrapper unset
 assert_log "config preflight -- --trace
-env:|sqlite:$common/gateway.db?mode=rwc|true
+env:|sqlite:$common/gateway.db?mode=rwc|
 --trace
-env:|sqlite:$common/gateway.db?mode=rwc|true"
+env:|sqlite:$common/gateway.db?mode=rwc|"
 
 assert_preflight_failure() {
   local name=$1
@@ -193,7 +193,7 @@ assert_preflight_failure() {
     exit 1
   fi
   assert_log "config preflight -- --config $canonical --trace
-env:|sqlite:$common/gateway.db?mode=rwc|true"
+env:|sqlite:$common/gateway.db?mode=rwc|"
 }
 
 printf 'legacy version = 1\n' >"$canonical"
diff --git a/tasks/scripts/test-snap-install-hook.sh b/tasks/scripts/test-snap-install-hook.sh
index aacea97bbb..e82cb64b55 100755
--- a/tasks/scripts/test-snap-install-hook.sh
+++ b/tasks/scripts/test-snap-install-hook.sh
@@ -15,6 +15,14 @@ cat >"$expected" <<'EOF'
 [openshell]
 version = 2
 
+[openshell.gateway]
+EOF
+
+legacy="${work}/legacy.toml"
+cat >"$legacy" <<'EOF'
+[openshell]
+version = 2
+
 [openshell.gateway]
 
 [openshell.gateway.auth]
@@ -34,6 +42,81 @@ cp "$common/gateway.toml" "${work}/operator-before"
 SNAP_COMMON="$common" "$hook"
 cmp -s "${work}/operator-before" "$common/gateway.toml"
 
+common="${work}/legacy"
+mkdir -p "$common"
+cp "$legacy" "$common/gateway.toml"
+chmod 644 "$common/gateway.toml"
+SNAP_COMMON="$common" "$hook"
+if ! cmp -s "$expected" "$common/gateway.toml"; then
+  echo "FAIL: install hook must migrate the legacy unauthenticated config" >&2
+  exit 1
+fi
+if [[ -z $(find "$common/gateway.toml" -perm 600) ]]; then
+  echo "FAIL: migrated config must be mode 0600" >&2
+  exit 1
+fi
+
+common="${work}/legacy-edited"
+mkdir -p "$common"
+cp "$legacy" "$common/gateway.toml"
+printf '\n# operator note\n' >>"$common/gateway.toml"
+cp "$common/gateway.toml" "${work}/legacy-edited-before"
+SNAP_COMMON="$common" "$hook"
+cmp -s "$expected" "$common/gateway.toml"
+
+common="${work}/custom-insecure"
+mkdir -p "$common"
+cat >"$common/gateway.toml" <<'EOF'
+[openshell]
+version = 2
+
+[openshell.gateway]
+compute_driver = "docker"
+disable_tls = true # old local override
+
+[openshell.gateway.auth]
+allow_unauthenticated_users = true # old local override
+EOF
+cp "$common/gateway.toml" "${work}/custom-insecure-before"
+SNAP_COMMON="$common" "$hook"
+cmp -s "$expected" "$common/gateway.toml"
+
+common="${work}/custom-secure"
+mkdir -p "$common"
+cat >"$common/gateway.toml" <<'EOF'
+[openshell]
+version = 2
+
+[openshell.gateway]
+compute_driver = "docker"
+# allow_unauthenticated_users = true
+EOF
+cp "$common/gateway.toml" "${work}/custom-secure-before"
+SNAP_COMMON="$common" "$hook"
+cmp -s "${work}/custom-secure-before" "$common/gateway.toml"
+
+common="${work}/post-refresh"
+mkdir -p "$common" "${work}/snap/meta/hooks"
+cp "$hook" "${work}/snap/meta/hooks/install"
+cp "${work}/legacy-edited-before" "$common/gateway.toml"
+mkdir -p "${work}/bin"
+cat >"${work}/bin/snapctl" <<EOF
+#!/bin/sh
+printf '%s\\n' "\$*" >>"${work}/snapctl.log"
+EOF
+chmod 755 "${work}/bin/snapctl"
+PATH="${work}/bin:$PATH" SNAP="${work}/snap" SNAP_COMMON="$common" \
+  SNAP_INSTANCE_NAME=openshell "${hook_dir}/post-refresh"
+if ! cmp -s "$expected" "$common/gateway.toml"; then
+  echo "FAIL: post-refresh hook must migrate an edited insecure config" >&2
+  exit 1
+fi
+if [[ $(cat "${work}/snapctl.log") != "restart openshell.gateway" ]]; then
+  echo "FAIL: post-refresh hook must restart the gateway" >&2
+  cat "${work}/snapctl.log" >&2
+  exit 1
+fi
+
 common="${work}/broken-link"
 mkdir -p "$common"
 ln -s "${work}/missing-target" "$common/gateway.toml"
@@ -51,4 +134,9 @@ if [[ ! -d "$common/gateway.toml" ]]; then
   exit 1
 fi
 
+if [[ -n $(find "$work" -name 'gateway.toml.pre-mtls*') ]]; then
+  echo "FAIL: install hook must not keep copies of replaced configs" >&2
+  exit 1
+fi
+
 echo "Snap install hook tests passed"