feat: switch SQLite to WAL mode and disable Btrfs CoW for data directory

- Change SQLite journal mode from DELETE to WAL for better concurrency
- Add chattr +C to /var/lib/aitbc in setup.sh to disable Btrfs Copy-on-Write
- Add fallback logging when chattr is unavailable or fails
- Prevent SQLite corruption on Btrfs filesystems by ensuring overwrite-in-place behavior

.windsurf/skills/ssh-access-patterns.md

@@ -0,0 +1,69 @@
+# SSH Access Patterns for AITBC Nodes
+
+## Purpose
+Document SSH access patterns for all AITBC nodes in the infrastructure.
+
+## Node Access Patterns
+
+### aitbc (localhost)
+Direct access - no SSH required.
+```bash
+# Run commands directly on localhost
+echo "command"
+systemctl restart service-name
+```
+
+### aitbc1
+Direct SSH access.
+```bash
+ssh aitbc1
+# Or execute single command
+ssh aitbc1 "command"
+```
+
+### gitea-runner (also hosts aitbc2)
+Direct SSH access. aitbc2 blockchain node runs on the same host.
+```bash
+ssh gitea-runner
+# Or execute single command
+ssh gitea-runner "command"
+```
+
+## Common Operations
+
+### Check service status on aitbc1
+```bash
+ssh aitbc1 "systemctl status aitbc-blockchain-node --no-pager"
+```
+
+### Restart service on gitea-runner (aitbc2)
+```bash
+ssh gitea-runner "systemctl restart aitbc-blockchain-node"
+```
+
+### Copy file to aitbc1
+```bash
+scp /path/to/file aitbc1:/path/to/destination
+```
+
+### Execute script on gitea-runner
+```bash
+ssh gitea-runner "bash /path/to/script.sh"
+```
+
+## Multi-Node Operations
+
+### Run command on all remote nodes
+```bash
+for node in aitbc1 gitea-runner; do
+  ssh "$node" "systemctl status aitbc-blockchain-node --no-pager"
+done
+```
+
+### Check block heights across all nodes
+```bash
+for node in aitbc1 gitea-runner; do
+  echo "=== $node ==="
+  ssh "$node" "curl -s http://localhost:8006/rpc/bestBlock | jq '.height'"
+done
+```

apps/blockchain-node/src/aitbc_chain/database.py

@@ -24,7 +24,7 @@ _engine = create_engine(f"sqlite:///{settings.db_path}", echo=False)
 @event.listens_for(_engine, "connect")
 def set_sqlite_pragma(dbapi_connection, connection_record):
     cursor = dbapi_connection.cursor()
-    cursor.execute("PRAGMA journal_mode=DELETE")
+    cursor.execute("PRAGMA journal_mode=WAL")
     cursor.execute("PRAGMA synchronous=NORMAL")
     cursor.execute("PRAGMA cache_size=-64000")
     cursor.execute("PRAGMA temp_store=MEMORY")

scripts/setup.sh

@@ -114,6 +114,13 @@ setup_runtime_directories() {
     chown root:root /var/log/aitbc
     chown root:root /etc/aitbc
     
+    # Disable Btrfs CoW on data directory to prevent SQLite corruption
+    # SQLite expects overwrite-in-place behavior, which conflicts with CoW
+    if command -v chattr >/dev/null 2>&1; then
+        chattr +C /var/lib/aitbc 2>/dev/null || log "Could not disable CoW (not Btrfs or no permissions)"
+        log "Disabled Btrfs CoW on /var/lib/aitbc to prevent SQLite corruption"
+    fi
+    
     # Create README files
     echo "# AITBC Runtime Data Directory" > /var/lib/aitbc/README.md
     echo "# Keystore for blockchain keys (SECURE)" > /var/lib/aitbc/keystore/README.md