Add the shared Claude Remote Control setup

Units, settings and setup README for the claude-rc user, which serves my projects' read-only MCP servers to the Claude app (negsplit for now).

.config/claude-rc/README.md

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+# Always-on Remote Control
+
+Reference copy of a machine setup: Claude Code Remote Control running as its own system user `claude-rc`, so my
+projects' read-only MCP servers (now: negsplit) can be used from the Claude app on the phone. One user and one
+session (`data`) for all projects. The user holds only read-only database logins; Bash runs sandboxed without
+network and can't read them (only the MCP servers, which run outside the sandbox, do). Nothing secret in this
+folder: the ntfy topic lives only in `/etc/claude-rc-notify.env`.
+
+Needs `claude-code`, `bubblewrap`, `socat` and each project's MCP server installed. Per project:
+
+- negsplit: the installed `negsplit` (with `python-mcp`) and the `garmin_ro` grants from its
+  `sql/garmin_ro_grants.sql`. A per-user query limit is a useful safety net (the session can lift it):
+
+  ```
+  mariadb -u root -p -e "ALTER USER 'garmin_ro'@'localhost' WITH MAX_STATEMENT_TIME 30;"
+  ```
+
+## Setup
+
+Run from this folder. User and folders:
+
+```
+doas useradd --system --create-home --home-dir /var/lib/claude-rc --shell /usr/bin/nologin claude-rc
+doas chmod 700 /var/lib/claude-rc
+doas install -d -o claude-rc -g claude-rc -m 700 /var/lib/claude-rc/.config /var/lib/claude-rc/.claude /var/lib/claude-rc/data /var/lib/claude-rc/data/.claude
+doas install -o claude-rc -g claude-rc -m 644 mcp.json /var/lib/claude-rc/data/.mcp.json
+doas install -o claude-rc -g claude-rc -m 644 project-settings.json /var/lib/claude-rc/data/.claude/settings.json
+doas install -o claude-rc -g claude-rc -m 644 user-settings.json /var/lib/claude-rc/.claude/settings.json
+```
+
+`strictAllowlist` must stay in the user settings: in project settings it has no effect.
+
+Each project's config holds only a `[readonly]` section. negsplit (`garmin_ro`):
+
+```
+doas install -d -o claude-rc -g claude-rc -m 700 /var/lib/claude-rc/.config/negsplit
+doas install -o claude-rc -g claude-rc -m 600 config.toml /var/lib/claude-rc/.config/negsplit/config.toml
+```
+
+Log in, trust the folder and enable Remote Control once, interactively:
+
+```
+doas -u claude-rc sh -c 'cd /var/lib/claude-rc/data && exec claude auth login'
+doas -u claude-rc sh -c 'cd /var/lib/claude-rc/data && exec claude'
+doas -u claude-rc sh -c 'cd /var/lib/claude-rc/data && exec claude remote-control --name data --spawn session'
+```
+
+ntfy topic for the failure alert (subscribe to it on ntfy.sh), then the units:
+
+```
+doas sh -c 'umask 077; printf "NTFY_TOPIC=claude-rc-%s\n" "$(openssl rand -hex 16)" > /etc/claude-rc-notify.env'
+doas install -m 644 claude-rc.service claude-rc-notify.service claude-rc-recover.service claude-rc-recover.timer -t /etc/systemd/system/
+doas systemctl daemon-reload
+doas systemctl enable --now claude-rc.service claude-rc-recover.timer
+```
+
+The service restarts with a growing delay (30 s to 10 min); after about 50 minutes of failures it gives up and
+sends the alert. The timer restarts it every 3 hours if it gave up, so a long network outage doesn't stop it for
+good. After upgrading a project's MCP server, or changing `mcp.json` or the settings, restart `claude-rc.service`
+so phone sessions use the new version.
+
+## Adding a project
+
+Add its server to `mcp.json` and `mcp__<server>` to the `allow` list in `project-settings.json` (plus a `Read` rule
+for its chart folder, if any), install its `[readonly]` config as above, reinstall the changed files and restart
+the service.
+
+## Dead login
+
+```
+doas systemctl stop claude-rc.service
+doas -u claude-rc sh -c 'cd /var/lib/claude-rc/data && exec claude auth login'
+doas systemctl reset-failed claude-rc.service
+doas systemctl start claude-rc.service
+```

.config/claude-rc/claude-rc-notify.service

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+[Unit]
+Description=Notify via ntfy that Claude Remote Control stopped
+
+[Service]
+Type=oneshot
+DynamicUser=yes
+# NTFY_TOPIC=...: root-only (0600), the topic is the only secret
+EnvironmentFile=/etc/claude-rc-notify.env
+TimeoutStartSec=10min
+ExecStart=/usr/bin/curl -fsS -m 30 --retry 5 --retry-delay 60 --retry-all-errors \
+    -H "Title: Claude Remote Control stopped" -H "Tags: warning" \
+    -d "%H: claude-rc.service keeps failing (dead login?). Retried every 3 h; fix at home: claude auth login as claude-rc." \
+    https://ntfy.sh/${NTFY_TOPIC}

.config/claude-rc/claude-rc-recover.service

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+[Unit]
+Description=Restart Claude Remote Control if it gave up (e.g. after a long network outage)
+
+[Service]
+Type=oneshot
+ExecCondition=/usr/bin/systemctl is-failed --quiet claude-rc.service
+ExecStart=/usr/bin/systemctl reset-failed claude-rc.service
+ExecStart=/usr/bin/systemctl start --no-block claude-rc.service

.config/claude-rc/claude-rc-recover.timer

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+[Unit]
+Description=Every 3 h, restart Claude Remote Control if it gave up
+
+[Timer]
+OnBootSec=1h
+OnUnitActiveSec=3h
+
+[Install]
+WantedBy=timers.target

.config/claude-rc/claude-rc.service

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+[Unit]
+Description=Claude Code Remote Control (read-only MCP servers)
+Wants=network-online.target
+After=network-online.target mariadb.service
+# about 50 min of failed starts (back-off below): give up and notify
+StartLimitIntervalSec=1h
+StartLimitBurst=8
+OnFailure=claude-rc-notify.service
+
+[Service]
+User=claude-rc
+Group=claude-rc
+WorkingDirectory=/var/lib/claude-rc/data
+# strips credentials from subprocess environments; on Linux also sandboxes ! shell commands
+Environment=CLAUDE_CODE_SUBPROCESS_ENV_SCRUB=1
+ExecStart=/usr/bin/claude remote-control --name data --spawn session
+Restart=always
+RestartSec=30s
+RestartSteps=4
+RestartMaxDelaySec=10min
+ProtectSystem=strict
+ProtectHome=yes
+ReadWritePaths=/var/lib/claude-rc
+PrivateTmp=yes
+NoNewPrivileges=yes
+ProtectKernelTunables=yes
+ProtectKernelModules=yes
+ProtectControlGroups=yes
+ProtectKernelLogs=yes
+ProtectClock=yes
+ProtectHostname=yes
+CapabilityBoundingSet=
+RestrictSUIDSGID=yes
+RestrictRealtime=yes
+LockPersonality=yes
+# no RestrictNamespaces/MemoryDenyWriteExecute: the Bash sandbox (bubblewrap) needs user namespaces
+
+[Install]
+WantedBy=multi-user.target

.config/claude-rc/mcp.json

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+{
+  "mcpServers": {
+    "negsplit": {
+      "command": "negsplit",
+      "args": ["mcp"]
+    }
+  }
+}

.config/claude-rc/project-settings.json

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+{
+  "permissions": {
+    "defaultMode": "default",
+    "disableBypassPermissionsMode": "disable",
+    "disableAutoMode": "disable",
+    "allow": [
+      "mcp__negsplit",
+      "Read(~/.local/share/negsplit/charts/**)"
+    ],
+    "deny": [
+      "Read(~/.config/**)",
+      "Read(~/.claude/**)",
+      "Read(~/.claude.json)",
+      "Edit(~/.config/**)",
+      "Edit(~/.claude/**)",
+      "Edit(~/.claude.json)",
+      "Edit(./.claude/**)",
+      "Edit(./.mcp.json)",
+      "WebFetch",
+      "WebSearch"
+    ]
+  },
+  "sandbox": {
+    "enabled": true,
+    "failIfUnavailable": true,
+    "allowUnsandboxedCommands": false,
+    "autoAllowBashIfSandboxed": true,
+    "filesystem": {
+      "denyRead": ["~/.config", "~/.claude", "~/.claude.json"],
+      "denyWrite": ["./.claude", "./.mcp.json"]
+    },
+    "network": {
+      "allowedDomains": []
+    }
+  }
+}

.config/claude-rc/user-settings.json

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+{
+  "theme": "dark",
+  "sandbox": {
+    "network": {
+      "strictAllowlist": true,
+      "allowedDomains": []
+    }
+  }
+}