diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1cc41a7..fa063e7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,15 +6,17 @@ on:
   pull_request:
     branches: [ main ]
 
-jobs:
-  lint:
-    name: PHP Lint + PHPCS
-    runs-on: ubuntu-latest
+permissions:
+  contents: read
 
+jobs:
+  # ── PHP Syntax Check ─────────────────────────────────────────────
+  lint-php:
+    name: PHP Lint (${{ matrix.php }})
+    runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: [ '8.0', '8.1', '8.2' ]
-
+        php: [ '8.1', '8.2', '8.3' ]
     steps:
       - uses: actions/checkout@v4
 
@@ -22,37 +24,30 @@ jobs:
         uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
-          tools: composer, cs2pr
-          extensions: mbstring
 
-      - name: PHP syntax check
+      - name: Syntax check all PHP files
         run: find . -name "*.php" -not -path "./vendor/*" | xargs -n 1 php -l
 
-      - name: Install PHPCS + WordPress standards
-        run: |
-          composer global require --with-all-dependencies \
-            "squizlabs/php_codesniffer=^3.13" \
-            "wp-coding-standards/wpcs=^3.0" \
-            "phpcsstandards/phpcsutils=^1.0"
-          phpcs --config-set installed_paths $(composer global config home)/vendor/wp-coding-standards/wpcs
+  # ── WordPress Coding Standards (PHP CodeSniffer) ──────────────────
+  lint-phpcs:
+    name: WordPress Coding Standards
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.1'
+
+      - name: Install Composer dependencies
+        run: composer install --no-interaction --prefer-dist --no-progress
 
       - name: Run PHPCS
-        run: |
-          phpcs --standard=WordPress --extensions=php \
-            --ignore=vendor/*,node_modules/*,tests/* \
-            --report=checkstyle \
-            --warning-severity=0 \
-            . | cs2pr || true
-
-      - name: Run PHPCS (strict — fail on errors)
-        run: |
-          phpcs --standard=WordPress --extensions=php \
-            --ignore=vendor/*,node_modules/*,tests/* \
-            --error-severity=1 --warning-severity=0 \
-            --report=summary \
-            .
+        run: composer run lint
         continue-on-error: true
 
+  # ── 300-line file check ──────────────────────────────────────────
   file-size:
     name: 300-line file check
     runs-on: ubuntu-latest
diff --git a/ARCHITECTURE.md b/ARCHITECTURE.md
index 9d18aa3..db9e11e 100644
--- a/ARCHITECTURE.md
+++ b/ARCHITECTURE.md
@@ -48,10 +48,12 @@ peptide-repo-core/
 ├── ARCHITECTURE.md                    # This file
 ├── CONVENTIONS.md                     # Naming patterns, extension guides
 ├── CHANGELOG.md                       # Semantic versioning changelog
+├── composer.json                      # Dev dependencies (PHPCS, WPCS) and lint scripts
+├── phpcs.xml.dist                     # PHPCS ruleset configuration
 │
 ├── .github/
 │   └── workflows/
-│       └── ci.yml                     # PHP lint (8.0-8.2), PHPCS, 300-line check
+│       └── ci.yml                     # PHP lint (8.1-8.3), PHPCS WordPress, 300-line check
 │
 ├── assets/
 │   └── css/
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000..ce73219
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,24 @@
+{
+	"name": "peptiderepo/peptide-repo-core",
+	"description": "Canonical peptide data layer for the peptiderepo.com ecosystem.",
+	"type": "wordpress-plugin",
+	"license": "GPL-2.0-or-later",
+	"require": {
+		"php": ">=8.1"
+	},
+	"require-dev": {
+		"squizlabs/php_codesniffer": "^3.13",
+		"wp-coding-standards/wpcs": "^3.0",
+		"phpcsstandards/phpcsutils": "^1.0",
+		"dealerdirect/phpcodesniffer-composer-installer": "^1.0"
+	},
+	"config": {
+		"allow-plugins": {
+			"dealerdirect/phpcodesniffer-composer-installer": true
+		}
+	},
+	"scripts": {
+		"lint": "phpcs",
+		"lint:fix": "phpcbf"
+	}
+}
diff --git a/peptide-repo-core.php b/peptide-repo-core.php
index fc35fcf..dfdabeb 100644
--- a/peptide-repo-core.php
+++ b/peptide-repo-core.php
@@ -8,7 +8,7 @@
  * Author URI:  https://peptiderepo.com
  * License:     GPL-2.0-or-later
  * Text Domain: peptide-repo-core
- * Requires PHP: 8.0
+ * Requires PHP: 8.1
  *
  * @see ARCHITECTURE.md — Full data flow and file tree.
  * @see CONVENTIONS.md  — Naming patterns and extension guides.
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
new file mode 100644
index 0000000..31dcb0a
--- /dev/null
+++ b/phpcs.xml.dist
@@ -0,0 +1,17 @@
+<?xml version="1.0"?>
+<ruleset name="Peptide Repo Core">
+	<description>WordPress coding standards for Peptide Repo Core.</description>
+
+	<file>.</file>
+
+	<exclude-pattern>/vendor/*</exclude-pattern>
+	<exclude-pattern>/node_modules/*</exclude-pattern>
+	<exclude-pattern>/tests/*</exclude-pattern>
+
+	<arg name="extensions" value="php"/>
+	<arg name="severity" value="1"/>
+	<arg name="warning-severity" value="0"/>
+	<arg value="sp"/>
+
+	<rule ref="WordPress"/>
+</ruleset>