diff --git a/.github/workflows/self-test.yml b/.github/workflows/self-test.yml
index 5af7b19..c4cfa2f 100644
--- a/.github/workflows/self-test.yml
+++ b/.github/workflows/self-test.yml
@@ -232,6 +232,8 @@ jobs:
           assert "setup_system_packages=false"
           assert "service_redis=false"
           assert "service_nats=false"
+          assert "service_postgres=false"
+          assert "service_mysql=false"
           echo "node-only: single-language path clean."
 
       - name: Assert outputs (python-poetry)
diff --git a/actions/environment-setup/action.yml b/actions/environment-setup/action.yml
index d3f3065..10279c5 100644
--- a/actions/environment-setup/action.yml
+++ b/actions/environment-setup/action.yml
@@ -103,6 +103,12 @@ outputs:
   service_nats:
     description: "Whether nats-server was installed onto PATH (true/false)"
     value: ${{ steps.config.outputs.service_nats }}
+  service_postgres:
+    description: "Whether PostgreSQL was installed + started (true/false). When true, POSTGRES_TEST_URL is set in the environment."
+    value: ${{ steps.config.outputs.service_postgres }}
+  service_mysql:
+    description: "Whether MySQL was installed + started (true/false). When true, MYSQL_TEST_URL is set in the environment."
+    value: ${{ steps.config.outputs.service_mysql }}
   setup_system_packages:
     description: "Whether apt system_packages were installed (true/false)"
     value: ${{ steps.config.outputs.setup_system_packages }}
@@ -547,11 +553,60 @@ runs:
         rm -rf "$TMP"
         nats-server --version
 
+    - name: Install + start PostgreSQL
+      if: steps.config.outputs.service_postgres == 'true' && runner.os == 'Linux'
+      shell: bash
+      run: |
+        set -euo pipefail
+        echo "🧰 Installing PostgreSQL via apt"
+        sudo apt-get update -y
+        sudo apt-get install -y --no-install-recommends postgresql postgresql-contrib
+        sudo service postgresql start
+        # Wait up to 20s for postgres to accept connections.
+        for i in {1..20}; do
+          if sudo -u postgres psql -c 'SELECT 1' >/dev/null 2>&1; then break; fi
+          sleep 1
+        done
+        sudo -u postgres psql -v ON_ERROR_STOP=1 <<'SQL'
+          CREATE USER mcpg WITH PASSWORD 'mcpg' CREATEDB;
+          CREATE DATABASE mcpg_test OWNER mcpg;
+        SQL
+        echo "POSTGRES_TEST_URL=postgres://mcpg:mcpg@localhost/mcpg_test" >> "$GITHUB_ENV"
+        psql --version
+
+    - name: Install + start MySQL
+      if: steps.config.outputs.service_mysql == 'true' && runner.os == 'Linux'
+      shell: bash
+      run: |
+        set -euo pipefail
+        echo "🧰 Installing MySQL via apt"
+        # GitHub's ubuntu-latest ships with mysql-server pre-installed on most
+        # releases; ensure it's actually available and running.
+        if ! command -v mysqld >/dev/null 2>&1; then
+          sudo apt-get update -y
+          sudo apt-get install -y --no-install-recommends mysql-server
+        fi
+        sudo service mysql start
+        for i in {1..20}; do
+          if sudo mysql -e 'SELECT 1' >/dev/null 2>&1; then break; fi
+          sleep 1
+        done
+        sudo mysql -v <<'SQL'
+          CREATE USER IF NOT EXISTS 'mcpg'@'127.0.0.1' IDENTIFIED BY 'mcpg';
+          CREATE USER IF NOT EXISTS 'mcpg'@'localhost' IDENTIFIED BY 'mcpg';
+          CREATE DATABASE IF NOT EXISTS mcpg_test;
+          GRANT ALL PRIVILEGES ON mcpg_test.* TO 'mcpg'@'127.0.0.1';
+          GRANT ALL PRIVILEGES ON mcpg_test.* TO 'mcpg'@'localhost';
+          FLUSH PRIVILEGES;
+        SQL
+        echo "MYSQL_TEST_URL=mysql://mcpg:mcpg@127.0.0.1/mcpg_test" >> "$GITHUB_ENV"
+        mysql --version
+
     - name: Warn on non-Linux services request
-      if: (steps.config.outputs.service_redis == 'true' || steps.config.outputs.service_nats == 'true') && runner.os != 'Linux'
+      if: (steps.config.outputs.service_redis == 'true' || steps.config.outputs.service_nats == 'true' || steps.config.outputs.service_postgres == 'true' || steps.config.outputs.service_mysql == 'true') && runner.os != 'Linux'
       shell: bash
       run: |
-        echo "::warning::services (redis/nats) currently install on Linux only; ignored on ${{ runner.os }}."
+        echo "::warning::services (redis/nats/postgres/mysql) currently install on Linux only; ignored on ${{ runner.os }}."
 
 
     # ══════════════════════════════════════════════════════════════════════════
@@ -587,8 +642,10 @@ runs:
         fi
 
         SERVICES=""
-        [[ "${{ steps.config.outputs.service_redis }}" == "true" ]] && SERVICES="${SERVICES}redis "
-        [[ "${{ steps.config.outputs.service_nats }}"  == "true" ]] && SERVICES="${SERVICES}nats "
+        [[ "${{ steps.config.outputs.service_redis }}"    == "true" ]] && SERVICES="${SERVICES}redis "
+        [[ "${{ steps.config.outputs.service_nats }}"     == "true" ]] && SERVICES="${SERVICES}nats "
+        [[ "${{ steps.config.outputs.service_postgres }}" == "true" ]] && SERVICES="${SERVICES}postgres "
+        [[ "${{ steps.config.outputs.service_mysql }}"    == "true" ]] && SERVICES="${SERVICES}mysql "
         if [[ -n "$SERVICES" ]]; then
           echo "| Services | ✅ ${SERVICES% } |" >> $GITHUB_STEP_SUMMARY
         fi
diff --git a/actions/environment-setup/schema.json b/actions/environment-setup/schema.json
index 965e961..5c26b4d 100644
--- a/actions/environment-setup/schema.json
+++ b/actions/environment-setup/schema.json
@@ -180,7 +180,7 @@
 
     "services": {
       "type": "object",
-      "description": "External daemons installed onto the runner's PATH so tests can spawn them as subprocesses (via Command::new(\"redis-server\") etc.). Each key toggles a specific service binary. Linux runners only for now.",
+      "description": "External daemons the runner needs for tests. `redis` and `nats` are installed onto PATH so tests can spawn them as subprocesses; `postgres` and `mysql` are installed AND auto-started with a test user/database, and the connection URL is exported as an env var for tests to read. Linux runners only for now.",
       "additionalProperties": false,
       "properties": {
         "redis": {
@@ -190,6 +190,14 @@
         "nats": {
           "type": "boolean",
           "description": "Install `nats-server` by downloading the latest stable release from github.com/nats-io/nats-server."
+        },
+        "postgres": {
+          "type": "boolean",
+          "description": "Install PostgreSQL via apt, start the daemon, create a `mcpg` user + `mcpg_test` database, and export `POSTGRES_TEST_URL=postgres://mcpg:mcpg@localhost/mcpg_test` so tests can connect."
+        },
+        "mysql": {
+          "type": "boolean",
+          "description": "Install MySQL via apt, start the daemon, create a `mcpg` user + `mcpg_test` database, and export `MYSQL_TEST_URL=mysql://mcpg:mcpg@127.0.0.1/mcpg_test` so tests can connect."
         }
       }
     },
diff --git a/actions/environment-setup/scripts/parse-config.sh b/actions/environment-setup/scripts/parse-config.sh
index cd3e1f3..660e776 100755
--- a/actions/environment-setup/scripts/parse-config.sh
+++ b/actions/environment-setup/scripts/parse-config.sh
@@ -90,6 +90,8 @@ if [[ ! -f "$CONFIG_FILE" ]]; then
     out "setup_c=false"
     out "service_redis=false"
     out "service_nats=false"
+    out "service_postgres=false"
+    out "service_mysql=false"
     exit 0
 fi
 
@@ -352,10 +354,15 @@ fi
 # ------------------------------------------------------------------------------
 SVC_REDIS=$(yq_get '.services.redis' "false")
 SVC_NATS=$(yq_get '.services.nats' "false")
+SVC_POSTGRES=$(yq_get '.services.postgres' "false")
+SVC_MYSQL=$(yq_get '.services.mysql' "false")
 out "service_redis=$SVC_REDIS"
 out "service_nats=$SVC_NATS"
-if [[ "$SVC_REDIS" == "true" || "$SVC_NATS" == "true" ]]; then
-    echo "  ✓ Services: redis=$SVC_REDIS, nats=$SVC_NATS"
+out "service_postgres=$SVC_POSTGRES"
+out "service_mysql=$SVC_MYSQL"
+if [[ "$SVC_REDIS" == "true" || "$SVC_NATS" == "true" \
+   || "$SVC_POSTGRES" == "true" || "$SVC_MYSQL" == "true" ]]; then
+    echo "  ✓ Services: redis=$SVC_REDIS, nats=$SVC_NATS, postgres=$SVC_POSTGRES, mysql=$SVC_MYSQL"
 fi
 
 echo "✅ Configuration parsed successfully"