KeiSeiKit-1.0/docs/USB-BRAIN-GUIDE-linux.md

USB Exobrain — Linux Walkthrough

Platform-specific companion to USB-BRAIN-GUIDE.md. Read the top-level guide first for prerequisites, warnings, and invariants.

On Linux, auto-mounted removable media typically lands at /media/$USER/<LABEL> (GNOME, KDE, auto-mounters) or /run/media/$USER/<LABEL> (systemd-udisks2). Substitute your actual mount point below.

1. Create the brain directory

BRAIN=/media/$USER/EXOBRAIN/my-brain
mkdir -p "$BRAIN"/{bin,memory,artifacts,manifests}

2. Download MCP server binaries

BASE=https://github.com/KeiSeiLab/KeiSeiKit-1.0/releases/download/v0.21.0
cd "$BRAIN/bin"
for n in darwin-arm64 darwin-x64 linux-x64 linux-arm64 windows-x64.exe; do
  curl -fL -O "$BASE/kei-mcp-server-$n" 2>/dev/null || echo "skipped $n"
  curl -fL -O "$BASE/kei-mcp-server-$n.sha256" 2>/dev/null || true
done

for f in kei-mcp-server-*.sha256; do sha256sum -c "$f"; done
chmod +x kei-mcp-server-linux-* kei-mcp-server-darwin-* 2>/dev/null || true

No Gatekeeper / xattr step on Linux. The chmod +x is still required — the executable bit is not restored by curl.

3. Write manifest.toml (schema v2)

cat > "$BRAIN/manifest.toml" <<'EOF'
[brain]
schema_version = 2
name = "my-brain"
created = "2026-04-22T00:00:00Z"

[paths]
memory = "memory/"
artifacts = "artifacts/"
manifests = "manifests/"

[paths.mcp_server]
darwin-arm64 = "bin/kei-mcp-server-darwin-arm64"
darwin-x64   = "bin/kei-mcp-server-darwin-x64"
linux-x64    = "bin/kei-mcp-server-linux-x64"
linux-arm64  = "bin/kei-mcp-server-linux-arm64"
windows-x64  = "bin/kei-mcp-server-windows-x64.exe"
EOF

4. Verify + attach

keisei list-adapters
keisei status                         # "no brain attached"
keisei attach "$BRAIN" --scope=user

Marker lands at ~/.keisei/attached.toml; Claude Code settings at ~/.claude/settings.json.

5. Verify in Claude Code

jq '.mcpServers["my-brain"]' ~/.claude/settings.json

6. Multi-client mount

keisei mount "$BRAIN"

Linux adapter paths: ~/.claude/settings.json, ~/.cursor/mcp.json, ~/.continue/config.json, ~/.config/zed/settings.json.

7. Project-scope

cd ~/path/to/your-repo
keisei attach "$BRAIN" --scope=project    # claude-code + cursor only

8. Detach + unmount

keisei detach
umount /media/$USER/EXOBRAIN             # or: sync && udisksctl unmount -b /dev/sdX1

If umount returns "target is busy", close any shell with its CWD under the mount, then retry. lsof +f -- /media/$USER/EXOBRAIN lists open handles.

Linux-specific troubleshooting

• Filesystem detection — keisei calls statfs(2) at load time. exFAT (EXFAT_SUPER_MAGIC = 0x2011bab0) and FAT32 (MSDOS_SUPER_MAGIC = 0x4d44) trigger the SQLite-WAL-unsafe advisory. Format the USB as ext4 for reliable multi-client use.
• Auto-mounted noexec partitions — some distros mount removable media noexec by default. If the mcp server refuses to run, remount read-write-executable: sudo mount -o remount,exec /media/$USER/EXOBRAIN. Alternatively add a line to /etc/fstab keyed by UUID (blkid /dev/sdX1).
• Permissions drift — if you copy a brain from macOS via tar / rsync, the executable bit may not survive. Re-apply chmod +x bin/kei-mcp-server-*.
• Optional — systemd auto-attach — a systemd-udev rule can run keisei attach <mount>/my-brain --scope=user whenever a labelled stick shows up, and a matching udev remove rule can call keisei detach. Out of scope for this guide; see ArchWiki: Udisks#Auto-mount.