PUBLICATION MESA-2026-003

REV. A — MARCH 2026

Saguaro

Open source AI code review for coding agents. Rules enforced inside Claude Code, Codex, Gemini CLI, and Cursor. Your agent fixes its own mistakes while context is hot.

$ npm install -g @mesadev/saguaro && sag init

Get Started View on GitHub

1.0IN ACTION

claude

$ claude "add cleanup job for expired sessions"

⏺Read 4 files

⏺Update(src/jobs/cleanup.ts)

⏺Ran stop hook

Saguaro review — fix valid issues, dismiss the rest.

[error] src/jobs/cleanup.ts:47 — Two sequential DELETEs (session_tokens then sessions) without a transaction. If the first succeeds but the second fails, tokens are removed but expired sessions remain — leaving dangling references. Wrap in db.transaction().

⏺Valid. Wrapping both deletes in a transaction.

⏺Update(src/jobs/cleanup.ts)

sag init sets this up automatically. The background reviewer looks at every change like a staff engineer. It catches bugs, security issues, and regressions without any configuration. The agent fixes findings while context is still hot.

For deterministic enforcement, Saguaro also supports rules: markdown files matched to changed files via globs:

.saguaro/rules/

no-raw-sql.md

require-error-boundary.md

use-server-functions.md

git diff main

M src/auth.ts

M src/api/users.ts

A src/components/Dashboard.tsx

codebase context

imports

dependents

related files

SAGUARO

1Match rules → files

2Gather context

3AI review per file

output

src/api/users.ts:42·no-raw-sql

Raw SQL string interpolation. Use parameterized queries.

2.0RULES

Rules are markdown files in .saguaro/rules/. Saguaro matches them to changed files via globs.

.saguaro/rules/no-raw-sql.md

1---
2id: no-raw-sql
3title: Use parameterized queries for all database calls
4severity: error
5globs:
6  - "src/api/**/*.ts"
7  - "src/db/**/*.ts"
8---
9
10Do not use string interpolation or concatenation to build SQL queries.
11Use parameterized queries or the ORM's query builder.
12
13### Violations
14
15```typescript
16const user = await db.query(`SELECT * FROM users WHERE id = ${id}`)
17```
18
19### Compliant
20
21```typescript
22const user = await db.query('SELECT * FROM users WHERE id = ?', [id])
23```

sag init generates rules from your codebase automatically, or write them by hand. sag rules generate adds more at any time.

3.0INTEGRATION

sag init wires everything automatically. Here's what it creates:

Claude Code

.claude/settings.json

1{
2  "hooks": {
3    "PreToolUse": [{
4      "matcher": "Edit|Write",
5      "hooks": [{
6        "type": "command",
7        "command": "sag hook pre-tool",
8        "timeout": 10
9      }]
10    }],
11    "Stop": [{
12      "hooks": [{
13        "type": "command",
14        "command": "sag hook run",
15        "timeout": 120
16      }]
17    }]
18  }
19}

PreToolUse injects relevant rules before the agent writes code. Stop reviews changes after each turn — blocks on violations.

Manual Review

terminal

$ sag review

src/api/users.ts:42·no-raw-sql[error]

Raw SQL string interpolation. Use parameterized queries.

| SELECT * FROM users WHERE id = ${id}

src/auth.ts:18·no-hardcoded-secrets[error]

Hardcoded API key. Use environment variables.

| const API_KEY = "sk-live-abc123..."

src/tracing.ts:31·otel-no-sensitive-params[warning]

Tracing credential object. Omit sensitive params from Tlm.trace.

| ['repoPath', 'credential']

3 violations: 2 errors, 1 warning

Files reviewed: 4 · Rules checked: 13 · Duration: 2.1s · Cost: $0.03

Run sag review on-demand to check your changes against all rules. JSON output available for CI.

Other Agents

Codex CLI	`sag review` — run manually or in CI
Gemini CLI	`sag review` — same CLI, same rules
Cursor	`sag review --output json` — deeplinks to violations
CI	`sag review --output json` — exit code 1 on errors

Background Daemon

For long sessions, sag daemon start reviews changes in parallel on localhost:7474 — findings surface as soft guidance, no blocking.

4.0SPECIFICATIONS

Execution	Fully local. Your code never leaves your machine.
AI Providers	Anthropic, OpenAI, Google — uses your agent CLI subscription, no API key needed
Agents	Claude Code, Codex CLI, Gemini CLI, Cursor
Review Modes	On-demand CLI, automatic stop hook, background daemon
Output	Console with file:line locations, JSON for CI, Cursor deeplinks
Rule Format	Markdown with YAML frontmatter, glob-based file matching
License	Apache-2.0 — fully open source
Package	@mesadev/saguaro
Source	github.com/mesa-dot-dev/saguaro

Full documentation