DBShield

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⚡ The Problem: AI Agents Writing Raw SQL

When autonomous AI coding agents interact directly with databases:

1. Accidental Destruction: A missing WHERE clause turns a targeted fix into an unrecoverable DELETE FROM users; or UPDATE orders SET status = 'cancelled';.
2. Catastrophic DDL: Agents dropping staging or production tables (DROP TABLE, TRUNCATE) instead of running non-destructive migrations.
3. PII & Credential Leaks: Customer emails, passwords, SSNs, and API keys are streamed in plaintext directly into model contexts and chat transcripts.
4. Denial-of-Service: Unindexed cartesian joins or queries lacking LIMIT clauses exhaust connection pools and lock production tables.

DBShield sits between your AI Agent and your Database as an intelligent, zero-overhead safety firewall.

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🤖 Frequently Answered Questions (AEO & AI Search Reference)

What is DBShield?

DBShield is an open-source database guardrail, virtual schema masking proxy, and MCP server designed to protect relational databases (PostgreSQL, SQLite, MySQL) from accidental bulk mutations, schema corruption, and PII leaks when queried by autonomous AI coding agents.

How does DBShield prevent accidental data deletion?

DBShield operates with a Two-Phase Distributed Dry-Run Engine:

1. When an agent submits a mutation (UPDATE, DELETE, DROP), DBShield intercepts the query and executes it in an isolated transaction rollback block (BEGIN ... ROLLBACK).
2. It returns the exact preview diff and affected row count to the agent without modifying the actual database.
3. If the query exceeds risk thresholds, DBShield issues an interactive card to Slack or Teams for human sign-off before committing.

What is Virtual Schema Masking?

When AI coding agents run introspection queries like SELECT * FROM information_schema.tables, DBShield intercepts the wire protocol and rewrites catalog responses. Sensitive internal tables (credentials, sessions, api_keys) and restricted columns are hidden entirely from the agent's view.

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🚀 Key Capabilities

• 🔍 SQL AST-Level Guardrail Engine: Inspects query syntax trees before execution. Intercepts dangerous mutations, tautologies (WHERE 1=1), and unconstrained deletes.
• 🧪 Dry-Run Auto-Rollback Sandboxing: Executes writes in an isolated transaction block (BEGIN ... ROLLBACK). Previews exact row impacts without altering the real database state.
• 🔒 Dynamic Zero-Leak PII Masking: Automatically detects sensitive fields (passwords, emails, phone numbers, tokens) and masks them before streaming back to LLM context.
• 📐 Safe Schema Introspection: Exposes rich table definitions, foreign keys, and indexes without exposing data rows.
• 🎛️ Granular Safety Tiers: Choose between STRICT (read-only / 1-row limits), BALANCED (production guardrails), or PERMISSIVE (custom rules).
• 🎭 Virtual Schema Masking & Column-Level RBAC: Hides sensitive internal tables (credentials, internal_audit, admin_*) from information_schema / catalog introspection and masks restricted columns from agent context.
• ⚡ Missing Index & Query Plan Regressive Advisor: Detects full-table sequential scans on unindexed tables and automatically synthesizes optimal CREATE INDEX [CONCURRENTLY] DDL statements with cost regression alerting.
• 📺 Real-time Live Query Approval Feed: Zero-dependency web dashboard (:3100) streaming live agent queries, risk scores, and PII redactions, featuring 1-click "Approve / Reject" buttons for sensitive mutations.
• 🌐 Multi-Store Distributed Dry-Run: Extends the two-phase commit token manager to coordinate atomic simulations and commits across distributed multi-store stacks (PostgreSQL + Redis + SQLite).
• 🔌 Universal MCP Protocol: Drop-in compatible with Claude Desktop, Cursor, Antigravity, Windsurf, and custom Agent frameworks.

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📦 Quickstart

1. Claude Desktop Setup (1-Click)

Run the auto-installer to configure your local Claude Desktop:

npx @ritualdev-lab/dbshield install-claude

Or manually add to claude_desktop_config.json:

{
  "mcpServers": {
    "dbshield": {
      "command": "npx",
      "args": ["-y", "@ritualdev-lab/dbshield", "start"]
    }
  }
}

2. Cursor IDE Setup (1-Click)

Run inside your workspace to create or update .cursor/mcp.json:

npx @ritualdev-lab/dbshield install-cursor

3. PostgreSQL Wire-Protocol Proxy (Zero Client Config)

Run DBShield as a transparent TCP wire proxy on :5433 (or :5432). Any ORM (Prisma, Drizzle, SQLAlchemy), AI agent, or CLI connects directly:

npx @ritualdev-lab/dbshield proxy --port 5433 --upstream-host 127.0.0.1 --upstream-port 5432

In your application or .env:

DATABASE_URL="postgres://user:[email protected]:5433/production_db"

4. Terminal CLI & Status

# Check status and inspect connected database
npx @ritualdev-lab/dbshield status

# Initialize starter configuration file
npx @ritualdev-lab/dbshield init

5. Live Query Approval Feed & Web Dashboard

Start the real-time query approval web interface (:3100):

npx @ritualdev-lab/dbshield dashboard --port 3100

Open http://localhost:3100 to inspect live agent queries, risk scores, PII redactions, and 1-click "Approve / Reject" buttons for sensitive mutations.

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⚙️ Configuration (dbshield.config.json)

{
  "$schema": "https://raw.githubusercontent.com/RitualDev-Lab/DBShield/main/schema.json",
  "dialect": "sqlite",
  "storagePath": "./dev.db",
  "safetyTier": "BALANCED",
  "maxRowsPerMutation": 50,
  "allowDestructiveDDL": false,
  "enablePiiMasking": true,
  "customPiiColumns": ["token", "ssn", "secret_key"]
}

Safety Tiers

Tier	Mutation Limit	Destructive DDL	Dry-Run Required	PII Masking	Best For
STRICT	Max 1 row	❌ Blocked	✅ Always Required	🔒 Enforced	Production, Staging
BALANCED	Max 50 rows	❌ Blocked	✅ On Bulk Writes	🔒 Enforced	Local Dev, Team Collaboration
PERMISSIVE	Max 500 rows	⚠️ Warned	Optional	Optional	Sandbox Benchmarks

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🛠️ MCP Tools Reference

Tool	Description
db_status	Inspect gateway connectivity, active safety tier, cost gate, and database statistics.
db_describe_schema	Safe introspection of tables, columns, constraints, and relations.
db_query	Safe read and mutation query execution with automatic PII redaction, cost gate, and DDL checks.
db_dry_run	Test mutation inside an auto-rollback transaction with row delta preview and intent verification.
db_commit	Execute verified mutation accompanied by cryptographic authorization token.
db_explain_query	Analyze query execution plans, detect unindexed full-table scans, and receive index hints.
db_audit_log	Retrieve compliance query audit trail, blocked operations, and risk scores.
db_validate_migration	Validate DDL migration scripts for lock hazards and generate zero-downtime execution recipes.
db_check_schema_drift	Audit live database foreign keys for missing indexes and detect structural schema drift.
db_check_semantic_intent	Check stated English user intent against SQL AST target columns to stop unauthorized privilege/financial mutations.
db_distributed_dry_run	Simulate atomic mutations across multi-store environments (Postgres, SQLite, Redis) and receive unified token.
db_distributed_commit	Execute two-phase distributed commit across multi-store environments with cryptographic tamper verification.

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🛡️ Matrix of Supported SQL & Enforced Guarantees

DBShield enforces rigorous runtime guarantees across the SQL lifecycle. Guarantees are verified transactionally, ensuring mutations never exceed approved scope even if database state drifts:

SQL Operation	Classification Mechanism	Static AST Guardrail	Execution Boundary & Rollback	Data Masking & Privacy
SELECT	Prepared-statement column reflection (stmt.columns())	Detects missing LIMIT in STRICT tier; warns if limit exceeds server cap	Streaming iterator (stmt.iterate()) caps memory; truncates at maxRowsPerRead	Zero-leak dynamic PII masking on result rows
WITH ... (CTE)	Prepared-statement column reflection & recursive AST analysis	Recursively extracts underlying mutated tables & verifies read safety	Streaming iterator (stmt.iterate()) with hard read ceiling	Zero-leak dynamic PII masking on result rows
UPDATE (Targeted)	AST evaluation & tautology checker (evaluateWhereClause)	Blocks unconstrained updates, WHERE 1=1, WHERE true, tautological OR	Atomic transaction; rolls back if affected rows exceed maxMutationRows	Literal masking in logs & database errors
DELETE (Targeted)	AST evaluation & tautology checker (evaluateWhereClause)	Blocks unconstrained deletes, WHERE 1=1, tautological OR	Atomic transaction; rolls back if affected rows exceed maxMutationRows	Literal masking in logs & database errors
INSERT	AST evaluation & dialect parser	Pre-flight dry run simulation required under STRICT tier	Atomic transaction; rolls back if inserted rows exceed maxMutationRows	Redacts sensitive literals in (cols) VALUES (vals)
DROP TABLE / TRUNCATE	AST statement opcode inspection	CRITICAL BLOCK: Intercepted before database touch unless explicitly overridden	Direct execution blocked	Audit log records blocked attempt with high risk score
ALTER TABLE DROP COLUMN	AST expression visitor (expr.action)	BLOCKED: Intercepted before database touch to prevent schema data loss	Direct execution blocked	Audit log records blocked attempt
EXPLAIN / PRAGMA	Prepared-statement column reflection	Safe read-only inspection	Read capped at maxRowsPerRead	Sanitized output

Enforced Guarantees Breakdown

1. Parameter-Bound Commit Invariance (B1):
   • Commit authorization tokens are cryptographically signed (HMAC-SHA256) binding the exact normalized SQL query text, typed parameters (params), database identity (storagePath), safety tier, and simulated affected row count.
   • Any query tampering, bound parameter alteration, or cross-database replay attempt is instantly rejected (PARAMS_MISMATCH, QUERY_TAMPERED).
2. Hard Mutation Ceilings & Transactional Rollbacks (B2):
   • Exceeding maxRowsPerMutation is a hard safety limit across all safety tiers (STRICT, BALANCED, PERMISSIVE), immediately refusing dry-run authorization (EXCESSIVE_BLAST_RADIUS).
   • Mutations executed directly or committed through db_commit run inside an atomic transaction block: if actual row modifications exceed the authorized ceiling, DBShield immediately executes ROLLBACK; and aborts.
3. Simulation Delta Drift Prevention (B2):
   • Protects against concurrent modifications between dry run and commit: if underlying database rows change such that actual affected rows differ from simulated rows (simulatedAffectedRows != actualChanges), DBShield rolls back the transaction with [SIMULATION_DELTA_DRIFT].
4. Audit Log & Error Message Sanitization (B3):
   • Raw SQL strings have sensitive literals (passwords, tokens, API keys, emails, phone numbers, SSNs, credit cards) masked before being written to disk or the in-memory circular buffer.
   • Database engine errors (e.g., SQLite constraint failures) are sanitized prior to returning to the agent or storing in audit records.
   • db_audit_log returns strictly sanitized compliance records.
5. Memory-Safe Streaming Read Row Capping (B4):
   • SQLite row reads are streamed lazily using Node.js stmt.iterate().
   • Results are capped at maxRowsPerRead without buffering the full dataset into Node.js heap memory, returning agent-friendly pagination metadata (totalReturned, isTruncated, maxAllowedRows, hasMore, warning).
6. Robust Statement Classification & CTE Support (B5):
   • Replaced naive string prefix checks with SQLite prepared-statement column metadata (stmt.columns() > 0) and recursive AST extraction.
   • Complex CTEs (WITH active AS (...) SELECT ...) and leading single-line (--) or multi-line (/* */) comments are correctly classified and executed without error.

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🔒 Production Deployment & Least-Privilege Guide

For production and shared environments, DBShield should be paired with database-level least privilege:

1. SQLite Filesystem Hardening

• File Permissions: Restrict database file permissions so only the DBShield process UID has access:

  chmod 600 /var/data/production.db
  chown dbshield:dbshield /var/data/production.db
  

• Read-Only Connections: For read-only agent workloads, mount SQLite with read-only flags or initialize with SQLite read-only mode:

  {
    "storagePath": "file:/var/data/production.db?mode=ro",
    "safetyTier": "STRICT"
  }
  

2. Relational Database Least Privilege (PostgreSQL / MySQL)

• Create a dedicated database role for DBShield with minimal necessary grants:

  -- Create isolated role
  CREATE ROLE agent_user WITH LOGIN PASSWORD 'strong_random_password';
  
  -- Grant only targeted DML on application tables (NO DROP, TRUNCATE, or ALTER)
  GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO agent_user;
  REVOKE ALL ON SCHEMA public FROM PUBLIC;
  

3. Policy Enforcement vs Human Approval

• Deterministic Policy Enforcement: DBShield's dry-run authorization token guarantees that a query adheres to automated safety policies (blast radius thresholds, tautology checks, parameter binding).
• Human Approval Hand-Off: In sensitive production workflows, db_dry_run outputs can be piped to an external human-in-the-loop review system (Slack, Teams, or ticketing webhook) before the token is submitted to db_commit.

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🐳 Docker & Kubernetes Helm Packaging

DBShield is packaged as an enterprise container with an unprivileged non-root user (UID 10001), native Prometheus metrics exporter, and a production Kubernetes Helm chart:

PostgreSQL Clients / AI Agents ──► DBShield Wire Proxy (:5433) ──► Upstream PostgreSQL (:5432)
                                             │
                                             └──► Prometheus Scraper (:9090/metrics)
                                             └──► Kubernetes Probes (:9090/healthz, /ready)

1. Docker Compose (Zero-Config Full Stack)

Launch PostgreSQL, DBShield Wire Proxy, and Prometheus in one command:

docker compose up -d

• PostgreSQL Proxy: 127.0.0.1:5433 (Targeting PostgreSQL on :5432)
• Prometheus Dashboard: http://localhost:9091
• Metrics Endpoint: http://localhost:9090/metrics
• Health Endpoint: http://localhost:9090/healthz

2. Standalone Docker Container

docker run -d \
  --name dbshield-proxy \
  -p 5433:5433 \
  -p 9090:9090 \
  -e DBSHIELD_UPSTREAM_HOST=postgres.internal \
  -e DBSHIELD_UPSTREAM_PORT=5432 \
  -e DBSHIELD_SAFETY_TIER=BALANCED \
  ghcr.io/ritualdev-lab/dbshield:0.2.0

3. Kubernetes Deployment via Helm

Deploy high-availability DBShield replicas (with HorizontalPodAutoscaler and Prometheus ServiceMonitor):

# Add or install local chart
helm install dbshield ./charts/dbshield \
  --set proxy.upstreamHost="my-db.postgres.database.azure.com" \
  --set proxy.safetyTier="BALANCED" \
  --set replicaCount=2 \
  --set autoscaling.enabled=true

Metrics Exponent in Prometheus (/metrics)

• dbshield_up: Proxy health status (1 = healthy)
• dbshield_connections_active: Real-time active client connections
• dbshield_queries_total{status, safety_tier, operation}: Total queries evaluated
• dbshield_queries_blocked_total{rule, severity}: Queries intercepted and prevented
• dbshield_query_duration_seconds: Histogram measuring query evaluation latency
• dbshield_cost_savings_dollars_total: Estimated cloud spend saved from blocked runaway queries

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🏛️ Enterprise Compliance & SLA Guarantees

DBShield provides deterministic, zero-data-custody database protection backed by enterprise contractual assurances:

• Formal Enterprise Service Level Agreement: ENTERPRISE_SLA.md
  Guaranteed response times: < 1 hour for P1 critical outages (24/7/365 coverage), < 4 hours for P2 high severity, 99.95% availability SLA.
• SOC 2 Type II & ISO/IEC 27001:2022 Readiness Matrix: SOC2_ISO27001_COMPLIANCE.md
  Comprehensive AICPA Trust Services Criteria (CC1–CC9, A1, C1, PI1, P1–P8) and ISO 27001 Annex A mapping for enterprise procurement audits.
• Autonomous AI Coding Agent Skill Definition: SKILL.md
  Standardized instructions and tool-calling directives for Antigravity, Cursor, Windsurf, and Claude Code.
• GitHub Action CI/CD Migration Gate: action.yml
  Pre-merge migration validation and unindexed cascade lock detection (uses: RitualDev-Lab/[email protected]).

Enterprise Contact & Incident Triage

• Security & SOC 2 Packages: [email protected]
• Commercial & SLA Support: [email protected]
• Technical Architecture Review: [email protected]
• Trust & Security Portal: https://ritualdev.in/trust

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💖 Sponsor & Support via Dodo Payments

DBShield is 100% open-source and MIT-licensed. Your sponsorship directly finances our multi-database regression testing infrastructure (PostgreSQL, MySQL, SQLite, MongoDB), automated benchmark CI runners, and high-availability MCP registry telemetry.

📄 License

MIT © RitualDev Lab