DeltaScope is an offline-first SQL audit engine for MySQL, TiDB, and PostgreSQL. The main product surfaces are deltascope, deltascope-server, and deltascope-mcp; PostgreSQL offline support is converged on the main archives for supported macOS and Linux platforms. It gives DBAs, application engineers, CI pipelines, and AI agents one consistent way to review DDL and DML before they reach a database.

Install

For macOS, prefer Homebrew. The repository installer script remains available as the generic portable installer for environments where Homebrew is not the right fit.

macOS (recommended):

brew tap Fanduzi/deltascope
brew install --cask deltascope

Generic installer:

curl -fsSL https://raw.githubusercontent.com/Fanduzi/DeltaScope/main/install.sh | sh

Pin a specific release:

curl -fsSL https://raw.githubusercontent.com/Fanduzi/DeltaScope/v0.42.0/install.sh | \
  DELTASCOPE_VERSION=v0.42.0 sh

PostgreSQL Support

DeltaScope supports PostgreSQL offline audit across CLI, HTTP, MCP, and pkg/deltascope surfaces:

• Primary-key fact support: PostgreSQL CREATE TABLE inline, table-level, named, and composite primary-key declarations populate DeltaScope's normalized primary-key contract. Existing primary-key rules (ddl.table.primary_key.bigint.require, ddl.table.primary_key.columns.max_count) now audit PostgreSQL CREATE TABLE statements.
• Generated/identity definition forms in CREATE TABLE and ALTER TABLE ... ADD COLUMN are processed through the normal audit path. Shared facts such as generated_when, is_identity, and identity_options are preserved where applicable.
• Generated/identity state-transition forms — ALTER TABLE ... ALTER COLUMN ... DROP EXPRESSION, SET GENERATED ALWAYS, SET GENERATED BY DEFAULT, and DROP IDENTITY — are processed through the normal audit path and produce explicit PostgreSQL-only rule findings (ddl.alter.drop_expression.forbid, ddl.alter.set_generated.forbid, ddl.alter.drop_identity.forbid).
• Unique/index rule coverage for standalone CREATE INDEX — PostgreSQL CREATE INDEX, CREATE UNIQUE INDEX, and CREATE INDEX CONCURRENTLY statements now trigger existing generic index rules (ddl.index.secondary.prefix.require, ddl.index.unique.prefix.require, ddl.index.columns.max_count) for approved btree forms.
• ALTER TABLE ADD CONSTRAINT fact support — PostgreSQL ALTER TABLE ... ADD PRIMARY KEY, ADD CONSTRAINT ... PRIMARY KEY, ADD UNIQUE, and ADD CONSTRAINT ... UNIQUE forms now preserve statement-local constraint metadata. Existing primary-key rules (ddl.table.primary_key.bigint.require, ddl.table.primary_key.columns.max_count) and unique prefix rule (ddl.alter.add_index.unique.prefix.require) produce findings for approved forms.
• ALTER TABLE ADD CONSTRAINT FOREIGN KEY fact support — PostgreSQL ALTER TABLE ... ADD CONSTRAINT ... FOREIGN KEY forms now preserve statement-local FK facts (local columns, referenced table, referenced columns, referenced schema for schema-qualified references). Existing FK rules (ddl.table.foreign_key.forbid, ddl.pg.table.foreign_key.cross_schema.advisory) produce findings for ALTER TABLE FK additions.
• ALTER TABLE constraint validation pairing — PostgreSQL ALTER TABLE ... ADD CONSTRAINT ... CHECK facts remain available for shared naming rules, and DeltaScope now adds the PostgreSQL-only GlobalRule ddl.pg.alter.not_valid_constraint.validate.require (default warning). It warns when a named CHECK or FOREIGN KEY NOT VALID constraint is not followed by a later matching ALTER TABLE ... VALIDATE CONSTRAINT ... in the same audited SQL batch, using the same schema + table + constraint name as the matching key. The warning is suppressed by a later match and is visible as a global finding across CLI, HTTP, MCP, and pkg/deltascope.
• Generated expression text is not evaluated or preserved, and DeltaScope still does not model full generated/identity lifecycle support or complete PostgreSQL sequence semantics.

See the audit capability matrix for detailed surface contracts and release notes for version-by-version changes.

Need PostgreSQL offline audit support?

• Install the normal DeltaScope main archive on supported macOS and Linux platforms; no separate PG-only installer is required.

The published core archive format is deltascope_<version>_<os>_<arch>.tar.gz. Development-oriented commands are documented under Dev docs.

Release Contract

Every tag produces core archives named deltascope_<version>_<os>_<arch>.tar.gz containing the deltascope, deltascope-server, and deltascope-mcp binaries. The supported darwin/amd64, darwin/arm64, linux/amd64, and linux/arm64 main archives are PG-capable and support PostgreSQL offline across all three binaries. The installer script, Homebrew Cask, and npm MCP launcher all resolve those platform-specific main archives from GitHub Release assets. See the npm package metadata for the current @fanduzi/deltascope-mcp package version.

Quick Start

Audit a risky DML statement:

deltascope audit --sql "delete from users"

Example excerpt:

Verdict: reject
Statements: 1
Blockers: 1
Warnings: 0
Notices: 0

Statement 1: DELETE
- [blocker] dml.where.require: UPDATE and DELETE statements must include a WHERE clause

Audit a CREATE TABLE statement:

deltascope audit --sql "create table tbl_users (id bigint unsigned not null auto_increment comment 'id', created_at datetime not null default current_timestamp comment 'created', updated_at datetime not null default current_timestamp on update current_timestamp comment 'updated', primary key (id)) comment='users' engine=InnoDB default charset=utf8mb4"

Example excerpt:

Verdict: review
Statements: 1
Blockers: 0
Warnings: 1
Notices: 0

Statement 1: CREATE TABLE
- [warning] ddl.column.default.require: column "id" should define a default value

Audit a file:

deltascope audit --file ./migrations/20260328_add_column.sql

Use JSON output for CI or agents:

deltascope audit \
  --sql "create table tbl_users (id bigint unsigned not null auto_increment comment 'id', created_at datetime not null default current_timestamp comment 'created', updated_at datetime not null default current_timestamp on update current_timestamp comment 'updated', primary key (id)) comment='users' engine=InnoDB default charset=utf8mb4" \
  --format json \
  --fail-on warning

Example JSON shape:

{
  "verdict": "review",
  "summary": {
    "statements": 1,
    "blockers": 0,
    "warnings": 1,
    "notices": 0
  },
  "statements": [ ... ],
  "context": {
    "mode": "offline",
    "dialect": "mysql",
    "dialect_source": "default"
  }
}

Audit a PostgreSQL migration with CI-native output:

deltascope audit --dialect postgresql --file ./migrations/20260409_add_index.sql --format github-actions

Audit a PostgreSQL CREATE TABLE statement with named and inline constraints:

deltascope audit \
  --dialect postgresql \
  --sql "create table orders (id bigint primary key, user_id bigint references users(id), amount numeric not null check (amount >= 0), constraint uniq_orders_user unique (user_id), constraint chk_orders_amount check (amount >= 0));"

Audit a PostgreSQL CREATE TABLE with a named foreign key referencing another table:

deltascope audit \
  --dialect postgresql \
  --sql "create table orders (user_id bigint, constraint fk_orders_user foreign key (user_id) references users(id));"

Audit a PostgreSQL phased migration follow-up statement:

deltascope audit \
  --dialect postgresql \
  --sql "alter table users alter column status set default 'active';"

Audit a PostgreSQL constraint lifecycle statement:

deltascope audit \
  --dialect postgresql \
  --sql "alter table users validate constraint chk_amount;"

Generate SARIF output for GitHub Code Scanning:

deltascope audit --file ./migrations.sql --dialect postgresql --format sarif > deltascope.sarif

When SQL looks like PostgreSQL but the dialect is set to MySQL, DeltaScope emits an advisory notice without auto-switching:

deltascope audit --sql "insert into users(id) values (1) returning id;" --format markdown

To audit PostgreSQL SQL explicitly:

deltascope audit --dialect postgresql --sql "insert into users(id) values (1) returning id;"

DML Impact Estimation

For a selective DML such as DELETE FROM users WHERE id = 42, DeltaScope may add an impact object to the statement result. The object is conservative by design and reports estimated_rows, estimated_ratio, risk_level, confidence, source, reason_codes, and optional notes.

{
  "raw_sql": "DELETE FROM users WHERE id = 42",
  "impact": {
    "estimated_rows": 1,
    "estimated_ratio": 0.0001,
    "risk_level": "low",
    "confidence": "high",
    "source": "metadata",
    "reason_codes": ["pk_equality"],
    "notes": ["refined with table statistics"]
  }
}

Offline mode uses SQL shape only. Metadata-aware mode may refine the estimate with read-only table statistics. DeltaScope does not execute the DML and does not run EXPLAIN ANALYZE.

Audit with live metadata (instance-aware rules):

deltascope audit \
  --sql "alter table orders add index idx_status (status)" \
  --host 127.0.0.1 --port 3306 --user root --ask-password --schema app

See all shipped rules:

deltascope rules

Why DeltaScope

SQL mistakes are cheap to catch before they run and expensive after. DeltaScope gives you one consistent engine across local dev, CI, HTTP service, and MCP so the same policy applies everywhere — no per-tool rule duplication, no dialect surprises.

Key Features

• Create-table governance across identifiers, comments, primary keys, audit columns, charset/collation, indexes, and table options.
• Alter-table governance for destructive actions, compatibility checks, existence validation, and merge guidance.
• Object-lifecycle checks for CREATE VIEW, DROP TABLE, and TRUNCATE TABLE.
• DML protections for WHERE, LIMIT, ORDER BY, subqueries, join conditions, bulk insert patterns, denylisted objects, and conservative affected-row impact estimation.
• Stable product surfaces: deltascope CLI, deltascope-server, deltascope-mcp, and pkg/deltascope.
• deltascope-mcp is the official MCP stdio server and exposes audit_sql, describe_rule, list_rules, and get_capabilities.

MCP Quick Start

No install required. The npm launcher fetches and runs the correct deltascope-mcp binary for your platform automatically.

Launcher requirements:

• Node.js 24 or newer
• supported native targets: darwin or linux, amd64 or arm64

Recommended launcher:

claude mcp add --scope user deltascope -- npx -y @fanduzi/deltascope-mcp
codex mcp add deltascope -- npx -y @fanduzi/deltascope-mcp

For raw stdio TOML, native deltascope-mcp, direct connection, connection_ref, proxy setup, and common errors, see Use DeltaScope MCP.

AI Agent Skill

Works in Claude Code, Codex, Cursor, and 40+ AI coding agents. Install once, get inline SQL review in every session.

DeltaScope ships a universal AI agent skill for inline SQL review during AI coding sessions. The skill detects whether DeltaScope is installed locally, calls it to audit your SQL, and surfaces findings with fix suggestions — without leaving your AI coding session.

# Install via npx skills (Claude Code, Codex, Cursor and 40+ AI agents)
npx skills add Fanduzi/DeltaScope --skill deltascope-review -a claude-code

Install globally (available across all projects):

npx skills add Fanduzi/DeltaScope --skill deltascope-review -a claude-code -g

Keep the skill up to date:

npx skills update

Then invoke in any supported AI session:

/deltascope-review

Paste a SQL snippet or point to a file — the agent audits it with DeltaScope and suggests fixes. See skills/README.md for full setup and usage.

More Docs

• Recipes
• Dev docs
• Reference docs
• Audit SQL with metadata
• Review DDL before migration
• Guard DML in CI
• Use with AI agents
• Inspect rules and config
• Troubleshoot metadata-aware audit

Documentation

• Admin docs
• Concept docs
• Dev docs
• Reference docs
• Audit capability matrix

Developer Workflows

• make test runs go test ./...
• make build produces all local binaries under bin/
• make build-linux produces Linux amd64 binaries under bin/
• make test-e2e-cli runs the Docker-backed metadata CLI smoke suite
• make pg-unit-test-gates runs the PostgreSQL-tagged unit gate set
• make pg-e2e-gates runs the Docker-backed PostgreSQL CLI, HTTP, and MCP suites
• make pg-confidence-gates runs the canonical PostgreSQL confidence closure
• docs/dev/testing.md covers the full target set

HTTP Service

Run the HTTP adapter over the same audit engine:

deltascope-server -listen 127.0.0.1:8083

Endpoints:

• GET /healthz
• GET /version
• POST /v1/audit

POST /v1/audit supports both offline JSON audit requests and metadata-aware requests with an optional connection block. The HTTP response keeps the public audit result body and adds a context block. See the full contract in HTTP API reference.

Library Usage

result, err := deltascope.Audit(ctx, deltascope.Request{
    SQL:     "delete from users",
    Dialect: deltascope.DialectMySQL,
})

The stable public API lives in pkg/deltascope.

Architecture

DeltaScope keeps one audit path and exposes it through multiple entrypoints. Product-level and implementation-level diagrams live in docs/concept/architecture.md and docs/dev/architecture.md.

Modules

Module	Description	Doc
cmd/deltascope	CLI process entrypoint	README
cmd/deltascope-server	HTTP service entrypoint	README
cmd/deltascope-mcp	MCP service entrypoint	README
internal/interfaces	Transport adapter namespace	README
internal/interfaces/cli	CLI adapter layer	README
internal/interfaces/http	HTTP adapter layer	README
internal/interfaces/mcp	MCP adapter layer	README
internal/application	Use-case orchestration layer	README
internal/application/audit	Application parse/audit orchestration	README
internal/application/auditmeta	Shared metadata-aware audit preparation	README
internal/application/policy	Application policy loader	README
internal/domain	Core domain types and rules	README
internal/domain/spec	Normalized statement specifications	README
internal/domain/rule	Rule findings and severity model	README
internal/domain/rule/catalog	Explanation-oriented shipped rule catalog	README
internal/domain/rule/ddl	DDL rule catalog	README
internal/domain/rule/dml	DML rule catalog	README
internal/domain/policy	Policy configuration model	README
internal/domain/report	Audit result aggregation and verdicts	README
internal/infrastructure	Infrastructure adapter layer	README
internal/infrastructure/parser	Parser adapter namespace	README
internal/infrastructure/parser/tidb	TiDB parser adapter	README
internal/infrastructure/config/viper	YAML config adapter	README
internal/infrastructure/metadata/mysql	Metadata provider for MySQL/TiDB-compatible engines	README
internal/infrastructure/output	Output renderer namespace	README
internal/infrastructure/output/markdown	Markdown renderer	README
internal/infrastructure/output/json	JSON renderer	README
configs	Example configuration files	README
pkg/deltascope	Stable public package surface	README