Composer Dependencies Update

Dependency updates are maintenance, not features. Do them regularly in small batches rather than rarely in large ones. Every update follows the same cycle: audit, update, verify, commit.

Core Principles

Principle	Meaning
Changelog first	Before any major dependency update, search the web for the package's changelog/UPGRADE file or ask the user to provide it -- never guess what changed
Security first	Run composer audit before and after every update -- vulnerabilities take priority over everything
Small batches	Update one package or one logical group at a time -- never update everything at once
Lock file is truth	Always commit composer.lock -- production uses composer install, never composer update
Verify before merging	Every update must pass the full test suite and static analysis before merging
Caret by default	Use ^ constraints for most dependencies -- it balances stability with receiving fixes

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Critical First Step: Read the Changelog

Before updating any dependency to a new major version, you MUST obtain the actual changelog:

1. Search the web for {package-name} CHANGELOG or {package-name} UPGRADE guide (e.g., doctrine/orm UPGRADE.md github)
2. Or ask the user to provide the changelog / release notes
3. Check the package's GitHub repository for CHANGELOG.md, UPGRADE.md, or release notes

This is non-negotiable for major updates. Each package has unique breaking changes that static skill knowledge cannot capture. For patch and minor updates, changelogs are recommended but not blocking.

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Update Strategies by Risk Level

Strategy	Scope	Risk	Frequency	Command
Patch only	Bug fixes (1.2.3 -> 1.2.4)	Lowest	Weekly	composer update --patch-only
Minor	New features, backward-compatible (1.2 -> 1.3)	Low	Biweekly	composer update --minor-only
Major	Breaking changes possible (1.x -> 2.0)	Highest	Planned, one at a time	composer update vendor/package --with-all-dependencies
Security	Vulnerability fixes	Urgent	Immediately	composer audit then targeted update

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Essential Commands

Command	Purpose
composer outdated --direct	Show outdated direct dependencies (skip transitive)
composer outdated --major-only	Show only packages with major updates available
composer outdated --minor-only	Show only packages with minor updates available
composer audit	Check locked versions against known security advisories
composer why vendor/package	Show which packages depend on a given dependency
composer why-not vendor/package 2.0	Show what prevents upgrading to a specific version
composer update vendor/package --with-all-dependencies	Update a package and all its dependents
composer bump	Raise lower bounds in composer.json to currently installed versions (apps only)
composer validate --strict	Validate composer.json structure and constraints

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Security Auditing

composer audit

Built into Composer since 2.4. Compares locked versions against GitHub Security Advisories and FriendsOfPHP databases.

# Check for known vulnerabilities
composer audit

# JSON output for CI parsing
composer audit --format=json

Returns non-zero exit code when vulnerabilities are found -- use as a CI gate.

Since Composer 2.9 (November 2025), composer update and composer require automatically block installation of packages with known security advisories by default.

roave/security-advisories

Preventive complement to composer audit. Declares conflict rules against all known vulnerable versions, preventing them from being installed.

composer require --dev roave/security-advisories:dev-latest

Must always be pinned to dev-latest (never a tagged version).

Quick check: composer update --dry-run roave/security-advisories

See Update Workflow Reference for the complete step-by-step update process.

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Version Constraints

Operator	Example	Range	Use Case
^ (caret)	^1.2.3	>=1.2.3 <2.0.0	Default for most dependencies
~ (tilde)	~1.2.3	>=1.2.3 <1.3.0	Conservative -- patch updates only
~ (minor)	~1.2	>=1.2.0 <2.0.0	Same as ^1.2 in practice
Exact	1.2.3	Only 1.2.3	Avoid except for known regressions
* (wildcard)	1.2.*	>=1.2.0 <1.3.0	Avoid in production

Pre-1.0 packages: The caret respects semver for unstable packages: ^0.3 means >=0.3.0 <0.4.0, and ^0.0.3 means >=0.0.3 <0.0.4.

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Lock File Management

Rule	Reason
Always commit composer.lock for applications	Ensures identical versions across all environments
Use composer install in CI and production	Reads from lock file, guarantees reproducible builds
Use composer update only intentionally	Resolves constraints anew, writes new lock file
Never edit composer.lock manually	Let Composer manage it
Use --no-dev in production	Exclude development dependencies
Use --optimize-autoloader in production	Generate optimized class map

Production install command:

composer install --no-dev --optimize-autoloader --no-interaction

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Abandoned Packages

Composer warns about abandoned packages during install/update. Handle them proactively:

1. Check the warning -- some suggest a replacement package directly
2. Search Packagist for maintained alternatives
3. Use composer why vendor/package to understand who depends on it
4. Wrap risky dependencies behind interfaces (adapter pattern) to make future replacement easier
5. Use composer-unused to find packages in composer.json that are not actually used in code

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Quick Reference: Update Checklist

• Run composer audit to check for security vulnerabilities
• Run composer outdated --direct to see what needs updating
• Create a dedicated branch for the update
• Update one package or logical group at a time
• Run full test suite after each update
• Run static analysis (PHPStan/Psalm)
• Run composer audit again post-update
• Commit both composer.json and composer.lock
• Optionally run composer bump to raise lower bounds (apps only)
• Deploy via composer install --no-dev --optimize-autoloader
• Monitor application behavior after deployment

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Reference Files

Reference	Contents
Update Workflow	Step-by-step update process, CI integration with Dependabot/Renovate, major update handling, and troubleshooting
Dependency Strategies	Versioning strategies, constraint selection, automated update tools configuration, and abandoned package handling

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Integration with Other Skills

Situation	Recommended Skill
Upgrading PHP version (may require dependency updates)	Use the php-upgrade playbook skill
Upgrading Symfony framework	Use the symfony-upgrade skill in frameworks/symfony/
Detecting N+1 query issues after ORM updates	Use the detect-n-plus-one skill