CODEOWNERS Patterns That Actually Scale

GitHub's CODEOWNERS file is one of those features that seems simple until you actually use it at scale. You add a few lines, assign some reviewers, and everything works — until your team grows, your monorepo expands, and suddenly every PR requires approval from someone who left six months ago.

Here's what works, what breaks, and how to keep CODEOWNERS useful as your team evolves.

The basics (and where they fall apart)

A typical CODEOWNERS file starts like this:

# Default owners
* @engineering-team

# Frontend
/src/frontend/ @frontend-team

# API
/src/api/ @backend-team

This works for a 10-person team with clear boundaries. It stops working when:

• Teams overlap. A PR touches both frontend and API. Now two teams are required reviewers, but neither feels ownership.
• People leave. The CODEOWNERS file references @sarah but Sarah left in October. Her reviews are required but can never be given.
• Directories restructure. You moved /src/api to /services/api but forgot to update CODEOWNERS. Now those files fall through to the default * rule.
• Too many owners. Every team adds themselves to directories they "might" care about. A PR in a shared utility folder requires approval from five teams.

Pattern 1: Narrow ownership, broad awareness

Instead of making everyone an owner, separate "must review" from "should know about."

# Auth module — security team MUST review
/src/auth/ @security-team

# Auth module — backend team gets notified but isn't required
# (handled via notification tooling, not CODEOWNERS)

CODEOWNERS should only include people whose approval is genuinely required. For awareness ("I want to know when this changes"), use notifications instead of blocking reviews.

This is where most teams get stuck. CODEOWNERS is the only built-in mechanism for routing review requests, so it gets overloaded with both "must approve" and "wants to know" use cases. They need different tools.

Pattern 2: Team handles, not individuals

Never put individual usernames in CODEOWNERS. People leave, change teams, go on vacation. Teams persist.

# Bad
/src/payments/ @alice @bob

# Good
/src/payments/ @payments-team

When Alice goes on parental leave, the team handle still works. When Bob moves to infrastructure, you update the team membership in one place — not in 30 lines of CODEOWNERS.

The maintenance cost of individual references grows linearly with team size. Team handles keep it constant.

Pattern 3: Last-match wins (use it intentionally)

CODEOWNERS rules are evaluated bottom-to-top, and the last matching pattern wins. This means order matters — a lot.

# Default: engineering team
* @engineering-team

# More specific: frontend team owns all .svelte files
*.svelte @frontend-team

# Most specific: design system components need design review
/src/lib/components/design-system/ @design-team @frontend-team

A common mistake is putting specific rules before general ones, where they get overridden by the catch-all at the bottom. The file reads top-to-bottom but matches bottom-to-top.

Tip: Structure your CODEOWNERS from most general (top) to most specific (bottom). Think of it like CSS specificity — last match wins.

Pattern 4: Protect what matters, ignore what doesn't

Not every file needs a code owner. Config files, generated code, documentation — these often don't need the same review rigor as production code.

# Don't require review for auto-generated files
/src/generated/ # (empty = no owner required)

# Lock files change with every dependency update
package-lock.json
yarn.lock
pnpm-lock.yaml

# But the security-sensitive config needs review
.github/workflows/ @platform-team
Dockerfile @platform-team

Leaving an empty owner (or not matching the path at all) means GitHub won't automatically request reviewers for those files. This reduces noise and lets reviewers focus on changes that actually need human judgment.

Pattern 5: Regular audits

CODEOWNERS files rot faster than almost any other config file in your repo. Set a quarterly reminder to:

1. Check for departed employees. Search for usernames that are no longer in the org.
2. Verify team handles exist. GitHub silently ignores invalid team references — the PR just won't get assigned.
3. Look for orphaned directories. If a path in CODEOWNERS no longer exists, remove the rule.
4. Check coverage. Are there important directories with no specific owner? Run git log --format='%H' -- | wc -l to find high-churn directories that might need explicit ownership.

Some teams automate this with CI checks that validate CODEOWNERS against org membership and directory structure. It's worth the setup time.

The notification gap

CODEOWNERS solves one problem well: ensuring the right people are required to approve changes to sensitive code. It doesn't solve the broader communication problem — making sure reviewers actually see the request promptly and can act on it.

A PR that requires @backend-team approval still needs someone on that team to notice the review request, have context on the changes, and prioritize it against their current work. GitHub sends email notifications by default, which is roughly equivalent to sending a letter by carrier pigeon.

Tenpace bridges this gap. When a PR is opened and CODEOWNERS assigns reviewers, Tenpace sends those reviewers a direct Slack message with the PR details. When the PR updates, the message updates in place. The reviewer doesn't have to find the notification — it finds them.

Set it up in three minutes — free during beta, works with your existing CODEOWNERS configuration.

Have a CODEOWNERS pattern that works well for your team? Share it with us: hello@tenpace.com