diff --git a/.github/WORKFLOWS.md b/.github/WORKFLOWS.md
index a46fb3b4b84..ec71eb833f5 100644
--- a/.github/WORKFLOWS.md
+++ b/.github/WORKFLOWS.md
@@ -520,6 +520,7 @@ Scripts in `.github/scripts/`:
 |-------------------------|-------------------|---------------------------|
 | `validate-docs-links.js`| Check doc URLs    | `util-check-docs-urls.yml`|
 | `send-build-stats.mjs`  | Build telemetry   | `setup-nodejs` action     |
+| `db-test-matrix.mjs`    | DB test matrix from `postgres-versions.json` | `ci-pull-requests.yml` |
 
 ### Slack Scripts
 
diff --git a/.github/docker-compose.yml b/.github/docker-compose.yml
index d741199d221..48cac0a073f 100644
--- a/.github/docker-compose.yml
+++ b/.github/docker-compose.yml
@@ -1,6 +1,6 @@
 services:
   postgres:
-    image: postgres:16
+    image: ${TEST_IMAGE_POSTGRES:?set it from packages/testing/containers/postgres-versions.json}
     restart: always
     environment:
       - POSTGRES_DB=n8n
@@ -8,5 +8,7 @@ services:
       - POSTGRES_PASSWORD=password
     ports:
       - 5432:5432
+    # Not PGDATA: Postgres 18+ moved it under /var/lib/postgresql/<major>/ and
+    # refuses to start when /var/lib/postgresql/data is mounted.
     tmpfs:
-      - /var/lib/postgresql/data
+      - /var/lib/postgresql
diff --git a/.github/scripts/db-test-matrix.mjs b/.github/scripts/db-test-matrix.mjs
new file mode 100644
index 00000000000..39a2a4538a0
--- /dev/null
+++ b/.github/scripts/db-test-matrix.mjs
@@ -0,0 +1,95 @@
+// Builds the job matrix for test-db-reusable.yml. Node builtins only: it runs in a
+// job that installs the monorepo's dependencies, not this folder's.
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../..');
+
+export const POSTGRES_VERSIONS_PATH = 'packages/testing/containers/postgres-versions.json';
+
+/** The matrix wall is bounded by its slowest leg, so a larger runner buys nothing. */
+const RUNNER = 'blacksmith-4vcpu-ubuntu-2204';
+
+/**
+ * @typedef {Object} PostgresVersions
+ * @property {string} primary
+ * @property {Array<{ major: number, image: string, support?: string }>} matrix
+ */
+
+/** @returns {PostgresVersions} */
+export function readPostgresVersions(repoRoot = REPO_ROOT) {
+	const file = path.join(repoRoot, POSTGRES_VERSIONS_PATH);
+	return JSON.parse(fs.readFileSync(file, 'utf8'));
+}
+
+/**
+ * Coverage and the schema-docs check run on the primary Postgres leg only, since
+ * the committed docs come from that one version.
+ *
+ * @param {PostgresVersions} versions
+ */
+export function buildMatrix(versions) {
+	const { primary, matrix } = versions;
+
+	if (!Array.isArray(matrix) || matrix.length === 0) {
+		throw new Error(`${POSTGRES_VERSIONS_PATH}: "matrix" must be a non-empty array`);
+	}
+
+	// Checked first: everything below treats the last entry as the newest.
+	const majors = matrix.map((entry) => entry.major);
+	for (let i = 1; i < majors.length; i++) {
+		if (majors[i] <= majors[i - 1]) {
+			throw new Error(
+				`${POSTGRES_VERSIONS_PATH}: "matrix" must be sorted by ascending major, got ${majors.join(', ')}`,
+			);
+		}
+	}
+
+	const newest = matrix[matrix.length - 1];
+	if (newest.image !== primary) {
+		throw new Error(
+			`${POSTGRES_VERSIONS_PATH}: "primary" (${primary}) must be the newest "matrix" entry's image (${newest.image})`,
+		);
+	}
+
+	// An exact minor keeps CI reproducible across Postgres point releases.
+	for (const { major, image } of matrix) {
+		const pinned = /^postgres:(\d+)\.\d+-alpine$/.exec(image);
+		if (!pinned) {
+			throw new Error(
+				`${POSTGRES_VERSIONS_PATH}: "${image}" must pin an exact minor, e.g. postgres:${major}.4-alpine`,
+			);
+		}
+		if (Number(pinned[1]) !== major) {
+			throw new Error(`${POSTGRES_VERSIONS_PATH}: "${image}" does not match major ${major}`);
+		}
+	}
+
+	return [
+		{
+			name: 'SQLite Pooled',
+			runner: RUNNER,
+			'test-cmd': 'pnpm test:sqlite',
+			'migration-cmd': 'pnpm test:sqlite:migrations',
+			'schema-check-cmd': 'pnpm --filter=@n8n/db schema:check:sqlite',
+			TEST_IMAGE_POSTGRES: undefined,
+			collectCoverage: 'false',
+		},
+		...matrix.map(({ major, image }) => ({
+			name: `Postgres ${major}`,
+			runner: RUNNER,
+			'test-cmd': 'pnpm test:postgres:integration:tc',
+			'migration-cmd': 'pnpm test:postgres:migrations:tc',
+			'schema-check-cmd': image === primary ? 'pnpm --filter=@n8n/db schema:check:postgres' : '',
+			TEST_IMAGE_POSTGRES: image,
+			collectCoverage: image === primary ? 'true' : 'false',
+		})),
+	];
+}
+
+// Skipped when imported by the tests.
+if (process.argv[1] === fileURLToPath(import.meta.url)) {
+	console.log(JSON.stringify(buildMatrix(readPostgresVersions())));
+}
diff --git a/.github/scripts/db-test-matrix.test.mjs b/.github/scripts/db-test-matrix.test.mjs
new file mode 100644
index 00000000000..c7dab805985
--- /dev/null
+++ b/.github/scripts/db-test-matrix.test.mjs
@@ -0,0 +1,128 @@
+import assert from 'node:assert/strict';
+import { describe, it } from 'node:test';
+
+import { buildMatrix, readPostgresVersions, POSTGRES_VERSIONS_PATH } from './db-test-matrix.mjs';
+
+// node --test ./.github/scripts/db-test-matrix.test.mjs
+
+const versions = () => ({
+	primary: 'postgres:18.4-alpine',
+	matrix: [
+		{ major: 16, support: 'compatibility', image: 'postgres:16.14-alpine' },
+		{ major: 17, support: 'supported', image: 'postgres:17.10-alpine' },
+		{ major: 18, support: 'supported', image: 'postgres:18.4-alpine' },
+	],
+});
+
+describe('postgres-versions.json', () => {
+	it('is valid, so the DB workflow can build a matrix from it', () => {
+		assert.doesNotThrow(() => buildMatrix(readPostgresVersions()));
+	});
+
+	it('covers the supported range plus one compatibility major', () => {
+		const { matrix } = readPostgresVersions();
+
+		const supported = matrix.filter((entry) => entry.support === 'supported');
+		const compatibility = matrix.filter((entry) => entry.support === 'compatibility');
+
+		assert.equal(supported.length, 2, `${POSTGRES_VERSIONS_PATH}: expected two supported majors`);
+		assert.equal(
+			compatibility.length,
+			1,
+			`${POSTGRES_VERSIONS_PATH}: expected one compatibility major`,
+		);
+		assert.ok(compatibility[0].major < Math.min(...supported.map((entry) => entry.major)));
+	});
+});
+
+describe('buildMatrix', () => {
+	it('emits one leg per database', () => {
+		const legs = buildMatrix(versions());
+
+		assert.deepEqual(
+			legs.map((leg) => leg.name),
+			['SQLite Pooled', 'Postgres 16', 'Postgres 17', 'Postgres 18'],
+		);
+	});
+
+	it('passes each Postgres leg its own pinned image', () => {
+		const legs = buildMatrix(versions());
+
+		assert.deepEqual(
+			legs.filter((leg) => leg.TEST_IMAGE_POSTGRES).map((leg) => leg.TEST_IMAGE_POSTGRES),
+			['postgres:16.14-alpine', 'postgres:17.10-alpine', 'postgres:18.4-alpine'],
+		);
+		assert.equal(legs[0].TEST_IMAGE_POSTGRES, undefined, 'SQLite leg needs no Postgres image');
+	});
+
+	it('runs every leg against both the integration and the migration suite', () => {
+		for (const leg of buildMatrix(versions())) {
+			assert.ok(leg['test-cmd'], `${leg.name} has no test command`);
+			assert.ok(leg['migration-cmd'], `${leg.name} has no migration command`);
+		}
+	});
+
+	it('collects coverage and checks schema docs on the primary Postgres leg only', () => {
+		const legs = buildMatrix(versions());
+
+		const collecting = legs.filter((leg) => leg.collectCoverage === 'true');
+		assert.deepEqual(
+			collecting.map((leg) => leg.name),
+			['Postgres 18'],
+		);
+
+		const checkingPostgresSchema = legs.filter(
+			(leg) => leg['schema-check-cmd'] === 'pnpm --filter=@n8n/db schema:check:postgres',
+		);
+		assert.deepEqual(
+			checkingPostgresSchema.map((leg) => leg.name),
+			['Postgres 18'],
+		);
+		const skipping = legs.filter((leg) => leg['schema-check-cmd'] === '');
+		assert.deepEqual(
+			skipping.map((leg) => leg.name),
+			['Postgres 16', 'Postgres 17'],
+		);
+	});
+
+	it('still checks the SQLite schema docs', () => {
+		const legs = buildMatrix(versions());
+
+		assert.equal(legs[0]['schema-check-cmd'], 'pnpm --filter=@n8n/db schema:check:sqlite');
+	});
+
+	it('rejects a primary that is not the newest major', () => {
+		const stale = { ...versions(), primary: 'postgres:17.10-alpine' };
+
+		assert.throws(() => buildMatrix(stale), /"primary".*must be the newest/);
+	});
+
+	it('rejects majors that are not in ascending order', () => {
+		const unsorted = versions();
+		[unsorted.matrix[0], unsorted.matrix[1]] = [unsorted.matrix[1], unsorted.matrix[0]];
+
+		assert.throws(() => buildMatrix(unsorted), /ascending major, got 17, 16, 18/);
+	});
+
+	it('rejects a floating image tag', () => {
+		const floating = {
+			primary: 'postgres:18-alpine',
+			matrix: [{ major: 18, image: 'postgres:18-alpine' }],
+		};
+
+		assert.throws(() => buildMatrix(floating), /must pin an exact minor/);
+	});
+
+	it('rejects an image whose major disagrees with its entry', () => {
+		const mismatched = {
+			primary: 'postgres:17.10-alpine',
+			matrix: [{ major: 18, image: 'postgres:17.10-alpine' }],
+		};
+
+		assert.throws(() => buildMatrix(mismatched), /does not match major 18/);
+	});
+
+	it('rejects an empty matrix', () => {
+		assert.throws(() => buildMatrix({ primary: 'postgres:18.4-alpine', matrix: [] }), /non-empty/);
+	});
+});
diff --git a/.github/workflows/ci-pull-requests.yml b/.github/workflows/ci-pull-requests.yml
index 282fbded6da..ac75a0dcc02 100644
--- a/.github/workflows/ci-pull-requests.yml
+++ b/.github/workflows/ci-pull-requests.yml
@@ -33,6 +33,7 @@ jobs:
       commit_sha: ${{ steps.commit-sha.outputs.sha }}
       merge_base: ${{ steps.ci-filter.outputs.merge-base }}
       matrix: ${{ steps.generate-matrix.outputs.matrix }}
+      db_test_matrix: ${{ steps.generate-db-test-matrix.outputs.db_test_matrix }}
       skip_tests: ${{ steps.generate-matrix.outputs.skip-tests }}
       affected_packages: ${{ steps.affected-packages.outputs.list }}
       changed_files: ${{ steps.ci-filter.outputs.changed-files }}
@@ -144,7 +145,10 @@ jobs:
               packages/@n8n/scheduler/src/**
               packages/cli/**/__tests__/**
               packages/testing/containers/services/postgres.ts
+              packages/testing/containers/postgres-versions.json
+              packages/testing/containers/test-containers.ts
               .github/workflows/test-db-reusable.yml
+              .github/scripts/db-test-matrix.mjs
               docs/generated/**
               .tbls.sqlite.yml
               .tbls.postgres.yml
@@ -175,6 +179,12 @@ jobs:
           echo "matrix=$MATRIX" >> "$GITHUB_OUTPUT"
           echo "skip-tests=$(node -e "process.stdout.write(JSON.parse(process.argv[1])[0]?.skip === true ? 'true' : 'false')" "$MATRIX")" >> "$GITHUB_OUTPUT"
 
+      # Generated here because a reusable workflow cannot resolve its own matrix.
+      - name: Generate DB test matrix
+        id: generate-db-test-matrix
+        if: fromJSON(steps.ci-filter.outputs.results).db
+        run: echo "db_test_matrix=$(node .github/scripts/db-test-matrix.mjs)" >> "$GITHUB_OUTPUT"
+
       - name: Compute affected packages
         id: affected-packages
         if: fromJSON(steps.ci-filter.outputs.results).unit
@@ -322,6 +332,7 @@ jobs:
     uses: ./.github/workflows/test-db-reusable.yml
     with:
       ref: ${{ needs.install-and-build.outputs.commit_sha }}
+      matrix: ${{ needs.install-and-build.outputs.db_test_matrix }}
 
   performance:
     name: Performance
diff --git a/.github/workflows/test-db-reusable.yml b/.github/workflows/test-db-reusable.yml
index 86987fa7b51..e51c6555d94 100644
--- a/.github/workflows/test-db-reusable.yml
+++ b/.github/workflows/test-db-reusable.yml
@@ -7,6 +7,10 @@ on:
         required: false
         type: string
         default: ''
+      matrix:
+        description: 'Job matrix JSON, from .github/scripts/db-test-matrix.mjs.'
+        required: true
+        type: string
 
 env:
   NODE_OPTIONS: '--max-old-space-size=6144'
@@ -19,24 +23,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        include:
-          - name: SQLite Pooled
-            runner: blacksmith-4vcpu-ubuntu-2204
-            test-cmd: pnpm test:sqlite
-            migration-cmd: pnpm test:sqlite:migrations
-            schema-check-cmd: pnpm --filter=@n8n/db schema:check:sqlite
-            collectCoverage: 'false'
-          - name: Postgres 16
-            # 4vcpu is enough since persistent-worker + template-DB make PG16
-            # complete in ~480s, which is now close to the SQLite leg (~360s)
-            # — the matrix wall is bounded by the slower leg, so the larger
-            # 8vcpu runner buys headroom we can't cash in anywhere.
-            runner: blacksmith-4vcpu-ubuntu-2204
-            test-cmd: pnpm test:postgres:integration:tc
-            migration-cmd: pnpm test:postgres:migrations:tc
-            schema-check-cmd: pnpm --filter=@n8n/db schema:check:postgres
-            TEST_IMAGE_POSTGRES: 'postgres:16'
-            collectCoverage: 'true'
+        include: ${{ fromJSON(inputs.matrix) }}
     env:
       TEST_IMAGE_POSTGRES: ${{ matrix.TEST_IMAGE_POSTGRES }}
       COVERAGE_ENABLED: ${{ matrix.collectCoverage }}
@@ -64,6 +51,7 @@ jobs:
       # postgres testcontainer) and fails if they differ from what's committed.
       # tbls runs as a Docker image in CI.
       - name: Verify schema docs are up to date
+        if: matrix.schema-check-cmd != ''
         run: ${{ matrix.schema-check-cmd }}
 
       - name: Upload coverage to Codecov
diff --git a/.github/workflows/util-data-tooling.yml b/.github/workflows/util-data-tooling.yml
index ebe8c29b5e8..e56ad34f0e0 100644
--- a/.github/workflows/util-data-tooling.yml
+++ b/.github/workflows/util-data-tooling.yml
@@ -68,6 +68,12 @@ jobs:
         if: fromJSON(steps.paths-filter.outputs.results).db
         uses: ./.github/actions/setup-nodejs
 
+      - name: Resolve Postgres image
+        if: fromJSON(steps.paths-filter.outputs.results).db
+        run: |
+          IMAGE=$(node -p "require('./packages/testing/containers/postgres-versions.json').primary")
+          echo "TEST_IMAGE_POSTGRES=$IMAGE" >> "$GITHUB_ENV"
+
       - name: Start Postgres
         if: fromJSON(steps.paths-filter.outputs.results).db
         uses: isbang/compose-action@4894d2492015c1774ee5a13a95b1072093087ec3 # v2.5.0
diff --git a/packages/@n8n/db/package.json b/packages/@n8n/db/package.json
index b9e45ab268b..a54f52cc361 100644
--- a/packages/@n8n/db/package.json
+++ b/packages/@n8n/db/package.json
@@ -60,6 +60,7 @@
     "@testcontainers/postgresql": "catalog:",
     "@vitest/coverage-v8": "catalog:",
     "express": "catalog:",
+    "n8n-containers": "workspace:*",
     "testcontainers": "catalog:",
     "@typescript/native": "catalog:typescript-tooling",
     "typescript": "catalog:typescript-tooling",
diff --git a/packages/@n8n/db/scripts/schema-docs.mjs b/packages/@n8n/db/scripts/schema-docs.mjs
index e5c3a3444c9..6b3a2741ec8 100644
--- a/packages/@n8n/db/scripts/schema-docs.mjs
+++ b/packages/@n8n/db/scripts/schema-docs.mjs
@@ -18,7 +18,7 @@
  * a local binary.
  */
 import { spawn, spawnSync } from 'node:child_process';
-import { mkdirSync, rmSync } from 'node:fs';
+import { mkdirSync, readFileSync, rmSync } from 'node:fs';
 import { dirname, relative, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
 
@@ -31,6 +31,15 @@ const TMP_DIR = resolve(PKG_ROOT, '.tmp-schema-docs');
 const TBLS_IMAGE =
 	'ghcr.io/k1low/tbls:v1.94.5@sha256:ae8a3bff6d4f8495d13a7982cd71fac3e8a3d1dd394888f2c44ef82216aa14e4';
 
+const POSTGRES_VERSIONS_PATH = resolve(
+	REPO_ROOT,
+	'packages/testing/containers/postgres-versions.json',
+);
+
+function primaryPostgresImage() {
+	return JSON.parse(readFileSync(POSTGRES_VERSIONS_PATH, 'utf8')).primary;
+}
+
 /** Thrown for expected, user-facing failures so `main`'s cleanup still runs. */
 class FailError extends Error {}
 
@@ -122,10 +131,10 @@ async function provision(dbType) {
 		};
 	}
 
-	// postgres: spin a throwaway container. Image tag matches the testcontainers
-	// default in `n8n-containers` (packages/testing/containers/test-containers.ts).
+	// postgres: spin a throwaway container on the version the rest of the test
+	// tooling defaults to.
 	const { PostgreSqlContainer } = await import('@testcontainers/postgresql');
-	const container = await new PostgreSqlContainer('postgres:18-alpine').start();
+	const container = await new PostgreSqlContainer(primaryPostgresImage()).start();
 	const conn = {
 		host: container.getHost(),
 		port: container.getMappedPort(5432),
diff --git a/packages/@n8n/db/src/connection/__tests__/db-connection-monitor.recovery.postgres.test.ts b/packages/@n8n/db/src/connection/__tests__/db-connection-monitor.recovery.postgres.test.ts
index 61bcb3dc87e..392d0a22950 100644
--- a/packages/@n8n/db/src/connection/__tests__/db-connection-monitor.recovery.postgres.test.ts
+++ b/packages/@n8n/db/src/connection/__tests__/db-connection-monitor.recovery.postgres.test.ts
@@ -2,6 +2,7 @@ import type { Logger } from '@n8n/backend-common';
 import type { DatabaseConfig } from '@n8n/config';
 import { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import type { ErrorReporter } from 'n8n-core';
 import net from 'node:net';
 import { getContainerRuntimeClient } from 'testcontainers';
@@ -94,11 +95,11 @@ class FreezableProxy {
  * a machine with no Postgres and no usable container runtime.
  *
  * To run it locally, boot a Postgres and export the host, e.g.:
- *   docker run --rm -e POSTGRES_PASSWORD=password -p 5432:5432 postgres:18-alpine
+ *   docker run --rm -e POSTGRES_PASSWORD=password -p 5432:5432 <POSTGRES_IMAGE>
  *   DB_POSTGRESDB_HOST=localhost DB_POSTGRESDB_PASSWORD=password \
  *     pnpm test db-connection-monitor.recovery.postgres
  */
-const POSTGRES_IMAGE = 'postgres:18-alpine';
+const POSTGRES_IMAGE = postgresVersions.primary;
 const CONTAINER_TIMEOUT_MS = 180_000;
 const TEST_TIMEOUT_MS = 60_000;
 
diff --git a/packages/@n8n/db/src/connection/__tests__/postgres-version-policy.test.ts b/packages/@n8n/db/src/connection/__tests__/postgres-version-policy.test.ts
index 73383946572..be73cb2a1f5 100644
--- a/packages/@n8n/db/src/connection/__tests__/postgres-version-policy.test.ts
+++ b/packages/@n8n/db/src/connection/__tests__/postgres-version-policy.test.ts
@@ -1,3 +1,5 @@
+import postgresVersions from 'n8n-containers/postgres-versions.json';
+
 import {
 	getPostgresVersionWarning,
 	OLDEST_COMPATIBILITY_POSTGRES_MAJOR,
@@ -36,3 +38,40 @@ describe('getPostgresVersionWarning', () => {
 		expect(getPostgresVersionWarning('')).toBeNull();
 	});
 });
+
+// These thresholds and the DB test matrix move together every November.
+describe('policy thresholds vs the versions CI tests', () => {
+	const tested = postgresVersions.matrix;
+
+	it('should stay silent for every fully supported major CI tests', () => {
+		const supported = tested.filter(({ support }) => support === 'supported');
+
+		for (const { major } of supported) {
+			expect(getPostgresVersionWarning(`${major}.0`), `Postgres ${major}`).toBeNull();
+		}
+	});
+
+	it('should warn about compatibility support only for the compatibility major CI tests', () => {
+		const compatibility = tested.filter(({ support }) => support === 'compatibility');
+
+		for (const { major } of compatibility) {
+			expect(getPostgresVersionWarning(`${major}.0`), `Postgres ${major}`).toContain(
+				'compatibility support only',
+			);
+		}
+	});
+
+	it('should treat the oldest tested major as the compatibility major', () => {
+		const oldest = Math.min(...tested.map(({ major }) => major));
+
+		expect(oldest).toBe(OLDEST_COMPATIBILITY_POSTGRES_MAJOR);
+	});
+
+	it('should treat the oldest fully supported tested major as the supported floor', () => {
+		const supported = tested
+			.filter(({ support }) => support === 'supported')
+			.map(({ major }) => major);
+
+		expect(Math.min(...supported)).toBe(OLDEST_SUPPORTED_POSTGRES_MAJOR);
+	});
+});
diff --git a/packages/@n8n/engine/package.json b/packages/@n8n/engine/package.json
index 2f27456f097..4e98fb2b86d 100644
--- a/packages/@n8n/engine/package.json
+++ b/packages/@n8n/engine/package.json
@@ -40,6 +40,7 @@
     "@types/express": "catalog:",
     "@types/pg": "^8.15.6",
     "@types/supertest": "^6.0.3",
+    "n8n-containers": "workspace:*",
     "supertest": "^7.1.1",
     "testcontainers": "catalog:",
     "typescript": "catalog:typescript",
diff --git a/packages/@n8n/engine/src/database/__tests__/workflow-execution.integration.test.ts b/packages/@n8n/engine/src/database/__tests__/workflow-execution.integration.test.ts
index 9e2e7e251b1..d22d5f8aed8 100644
--- a/packages/@n8n/engine/src/database/__tests__/workflow-execution.integration.test.ts
+++ b/packages/@n8n/engine/src/database/__tests__/workflow-execution.integration.test.ts
@@ -1,5 +1,6 @@
 import type { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
 import { createDataSource } from '../data-source';
@@ -10,7 +11,7 @@ describe('workflow_execution table (integration)', () => {
 	let dataSource: DataSource;
 
 	beforeAll(async () => {
-		container = await new PostgreSqlContainer('postgres:18-alpine').start();
+		container = await new PostgreSqlContainer(postgresVersions.primary).start();
 		dataSource = createDataSource(container.getConnectionUri());
 		await dataSource.initialize();
 		await dataSource.runMigrations();
diff --git a/packages/@n8n/engine/src/database/__tests__/workflow-step-execution.integration.test.ts b/packages/@n8n/engine/src/database/__tests__/workflow-step-execution.integration.test.ts
index 35b6a03a441..a9734d966c1 100644
--- a/packages/@n8n/engine/src/database/__tests__/workflow-step-execution.integration.test.ts
+++ b/packages/@n8n/engine/src/database/__tests__/workflow-step-execution.integration.test.ts
@@ -1,5 +1,6 @@
 import type { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import { afterAll, beforeAll, describe, expect, it } from 'vitest';
 
 import type { StepStatus } from '../../execution/execution.types';
@@ -14,7 +15,7 @@ describe('workflow_step_execution table (integration)', () => {
 	let dataSource: DataSource;
 
 	beforeAll(async () => {
-		container = await new PostgreSqlContainer('postgres:18-alpine').start();
+		container = await new PostgreSqlContainer(postgresVersions.primary).start();
 		dataSource = createDataSource(container.getConnectionUri());
 		await dataSource.initialize();
 		await dataSource.runMigrations();
diff --git a/packages/@n8n/engine/src/execution/__tests__/execution-start.integration.test.ts b/packages/@n8n/engine/src/execution/__tests__/execution-start.integration.test.ts
index d63f1029487..3b27b095e59 100644
--- a/packages/@n8n/engine/src/execution/__tests__/execution-start.integration.test.ts
+++ b/packages/@n8n/engine/src/execution/__tests__/execution-start.integration.test.ts
@@ -1,5 +1,6 @@
 import type { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
 
 import { AllowAllAdmittance } from '../../admittance';
@@ -35,7 +36,7 @@ describe('execution start (integration)', () => {
 	let dataSource: DataSource;
 
 	beforeAll(async () => {
-		container = await new PostgreSqlContainer('postgres:18-alpine').start();
+		container = await new PostgreSqlContainer(postgresVersions.primary).start();
 		dataSource = createDataSource(container.getConnectionUri());
 		await dataSource.initialize();
 		await dataSource.runMigrations();
diff --git a/packages/@n8n/engine/src/execution/__tests__/step-execution.integration.test.ts b/packages/@n8n/engine/src/execution/__tests__/step-execution.integration.test.ts
index 4ba471e4e80..c0d060b8fdc 100644
--- a/packages/@n8n/engine/src/execution/__tests__/step-execution.integration.test.ts
+++ b/packages/@n8n/engine/src/execution/__tests__/step-execution.integration.test.ts
@@ -1,5 +1,6 @@
 import type { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
 
 import { AllowAllAdmittance } from '../../admittance';
@@ -34,7 +35,7 @@ describe('step execution (integration)', () => {
 	let dataSource: DataSource;
 
 	beforeAll(async () => {
-		container = await new PostgreSqlContainer('postgres:18-alpine').start();
+		container = await new PostgreSqlContainer(postgresVersions.primary).start();
 		dataSource = createDataSource(container.getConnectionUri());
 		await dataSource.initialize();
 		await dataSource.runMigrations();
diff --git a/packages/@n8n/engine/src/server/__tests__/workflow-executions.integration.test.ts b/packages/@n8n/engine/src/server/__tests__/workflow-executions.integration.test.ts
index 719c37b94c8..2f216d7761a 100644
--- a/packages/@n8n/engine/src/server/__tests__/workflow-executions.integration.test.ts
+++ b/packages/@n8n/engine/src/server/__tests__/workflow-executions.integration.test.ts
@@ -1,5 +1,6 @@
 import type { DataSource } from '@n8n/typeorm';
 import { PostgreSqlContainer, type StartedPostgreSqlContainer } from '@testcontainers/postgresql';
+import postgresVersions from 'n8n-containers/postgres-versions.json';
 import request from 'supertest';
 import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
 
@@ -22,7 +23,7 @@ describe('POST /api/workflow-executions (integration)', () => {
 	let stop: () => Promise<void>;
 
 	beforeAll(async () => {
-		container = await new PostgreSqlContainer('postgres:18-alpine').start();
+		container = await new PostgreSqlContainer(postgresVersions.primary).start();
 		dataSource = createDataSource(container.getConnectionUri());
 		await dataSource.initialize();
 		await dataSource.runMigrations();
diff --git a/packages/cli/test/integration/database/repositories/credentials.repository.test.ts b/packages/cli/test/integration/database/repositories/credentials.repository.test.ts
index 2a794048326..686ab249593 100644
--- a/packages/cli/test/integration/database/repositories/credentials.repository.test.ts
+++ b/packages/cli/test/integration/database/repositories/credentials.repository.test.ts
@@ -544,16 +544,20 @@ describe('CredentialsRepository', () => {
 			const projectRoles = await roleService.rolesWithScope('project', scopes);
 			const credentialRoles = await roleService.rolesWithScope('credential', scopes);
 
+			// Both approaches need an explicit order: without one, Postgres is free to
+			// return the rows in any order, and the two queries use different plans.
 			const oldOptions = {
 				filter: { projectId: teamProject.id, name: 'Test' },
 				take: 2,
 				skip: 0,
+				order: { id: 'ASC' as const },
 			};
 
 			const newOptions = {
 				filter: { name: 'Test' },
 				take: 2,
 				skip: 0,
+				order: { id: 'ASC' as const },
 			};
 
 			// ACT - Old Approach
@@ -574,7 +578,7 @@ describe('CredentialsRepository', () => {
 			expect(newResult.count).toBe(oldResult[1]);
 			expect(newResult.credentials).toHaveLength(oldResult[0].length);
 
-			// Check same credentials in same order (sorting should be consistent)
+			// Check same credentials in same order
 			const oldIds = oldResult[0].map((c) => c.id);
 			const newIds = newResult.credentials.map((c) => c.id);
 			expect(newIds).toEqual(oldIds);
diff --git a/packages/testing/containers/HELM-TESTING.md b/packages/testing/containers/HELM-TESTING.md
index dc95521bb8f..360e6f1bb91 100644
--- a/packages/testing/containers/HELM-TESTING.md
+++ b/packages/testing/containers/HELM-TESTING.md
@@ -91,7 +91,9 @@ pnpm stack:helm --image ghcr.io/n8n-io/n8n:ci-12345
 ### CLI Options
 
 ```
---mode <mode>         standalone (SQLite, default) or queue (PostgreSQL + Redis + workers)
+--mode <mode>         standalone (SQLite, default) or queue (PostgreSQL + Redis + workers).
+                      Queue mode's Postgres chart and image are pinned in
+                      postgres-versions.json.
 --image <image>       n8n Docker image (default: n8nio/n8n:local)
 --chart-ref <ref>     Git branch/tag for n8n-hosting (default: main)
 --chart-repo <url>    Git repo URL (default: https://github.com/n8n-io/n8n-hosting.git)
diff --git a/packages/testing/containers/README.md b/packages/testing/containers/README.md
index 11291788910..c86382500f7 100644
--- a/packages/testing/containers/README.md
+++ b/packages/testing/containers/README.md
@@ -349,7 +349,7 @@ Now usable as `test.use({ capability: 'my-capability' })`.
 
 | Service | Helper | Description |
 |---------|--------|-------------|
-| `postgres` | - | PostgreSQL database |
+| `postgres` | - | PostgreSQL database (version from `postgres-versions.json`) |
 | `redis` | - | Redis for queue mode |
 | `mailpit` | ✓ | Email testing (SMTP + UI) |
 | `gitea` | ✓ | Git server for source control |
diff --git a/packages/testing/containers/helm-stack.ts b/packages/testing/containers/helm-stack.ts
index d4b9121f62b..9ad639c9bbc 100644
--- a/packages/testing/containers/helm-stack.ts
+++ b/packages/testing/containers/helm-stack.ts
@@ -12,6 +12,7 @@ import { homedir, tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { setTimeout as wait } from 'node:timers/promises';
 
+import postgresVersions from './postgres-versions.json';
 import { TEST_CONTAINER_IMAGES } from './test-containers';
 
 const DEFAULT_K3S_IMAGE = 'rancher/k3s:v1.32.2-k3s1';
@@ -236,9 +237,13 @@ function deployQueueInfrastructure(env: NodeJS.ProcessEnv): void {
 		'Add Bitnami repo',
 	);
 
-	log('Deploying PostgreSQL...');
+	// By digest because the Bitnami catalog only publishes `postgresql:latest`,
+	// which the chart defaults to.
+	const { chartVersion, imageDigest } = postgresVersions.helm;
+
+	log(`Deploying PostgreSQL (chart ${chartVersion})...`);
 	execOnHost(
-		'helm install postgresql bitnami/postgresql --set auth.username=n8n --set auth.password=n8n-test-password --set auth.database=n8n --set primary.resources.requests.cpu=100m --set primary.resources.requests.memory=256Mi --set primary.resources.limits.cpu=500m --set primary.resources.limits.memory=512Mi --wait --timeout 3m',
+		`helm install postgresql bitnami/postgresql --version ${chartVersion} --set image.digest=${imageDigest} --set auth.username=n8n --set auth.password=n8n-test-password --set auth.database=n8n --set primary.resources.requests.cpu=100m --set primary.resources.requests.memory=256Mi --set primary.resources.limits.cpu=500m --set primary.resources.limits.memory=512Mi --wait --timeout 3m`,
 		env,
 		'Deploy PostgreSQL',
 	);
diff --git a/packages/testing/containers/postgres-versions.json b/packages/testing/containers/postgres-versions.json
new file mode 100644
index 00000000000..0a296198fef
--- /dev/null
+++ b/packages/testing/containers/postgres-versions.json
@@ -0,0 +1,12 @@
+{
+	"primary": "postgres:18.4-alpine",
+	"matrix": [
+		{ "major": 16, "support": "compatibility", "image": "postgres:16.14-alpine" },
+		{ "major": 17, "support": "supported", "image": "postgres:17.10-alpine" },
+		{ "major": 18, "support": "supported", "image": "postgres:18.4-alpine" }
+	],
+	"helm": {
+		"chartVersion": "18.8.7",
+		"imageDigest": "sha256:09a0a8dc1c52c5a0c4ccc7febe3d4d4df1e5d50816e2312ef0e21d3c09084ec0"
+	}
+}
diff --git a/packages/testing/containers/test-containers.ts b/packages/testing/containers/test-containers.ts
index 4a0aa6e5ddb..2915126e339 100644
--- a/packages/testing/containers/test-containers.ts
+++ b/packages/testing/containers/test-containers.ts
@@ -20,9 +20,11 @@
  * N8N_DOCKER_IMAGE is also supported for backwards compatibility.
  */
 
+import postgresVersions from './postgres-versions.json';
+
 /** Default images - override via TEST_IMAGE_<KEY> env vars */
 const DEFAULT_IMAGES = {
-	postgres: 'postgres:18-alpine',
+	postgres: postgresVersions.primary,
 	redis: 'redis:alpine',
 	caddy: 'caddy:alpine',
 	n8n: 'n8nio/n8n:local',
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c95fcdef1b6..3cf956b14d1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -2161,6 +2161,9 @@ importers:
       express:
         specifier: 'catalog:'
         version: 5.1.0
+      n8n-containers:
+        specifier: workspace:*
+        version: link:../../testing/containers
       testcontainers:
         specifier: 'catalog:'
         version: 11.13.0
@@ -2290,6 +2293,9 @@ importers:
       '@types/supertest':
         specifier: ^6.0.3
         version: 6.0.3
+      n8n-containers:
+        specifier: workspace:*
+        version: link:../../testing/containers
       supertest:
         specifier: ^7.1.1
         version: 7.1.1