Fix YAML date coercion

components/framework/index.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const YAML = require('js-yaml');
+const yamlSchema = require('../../src/utils/yaml-schema');
 const path = require('path');
 const spawn = require('../../src/utils/spawn');
 const redactArgs = require('../../src/utils/redact-args');
@@ -162,7 +163,7 @@ class ServerlessFramework {
   async retrieveFunctions() {
     const { stdout: printOutput } = await this.exec('serverless', ['print']);
     try {
-      return YAML.load(printOutput.toString()).functions || {};
+      return YAML.load(printOutput.toString(), { schema: yamlSchema }).functions || {};
     } catch {
       throw new Error(`Could not retrieve functions from configuration:\n${printOutput}`);
     }
@@ -327,7 +328,7 @@ class ServerlessFramework {
   async retrieveOutputs() {
     const { stdout: infoOutput } = await this.exec('serverless', ['info', '--verbose']);
     try {
-      return YAML.load(infoOutput.toString())['Stack Outputs'];
+      return YAML.load(infoOutput.toString(), { schema: yamlSchema })['Stack Outputs'];
     } catch {
       if (infoOutput.toString()) {
         // Try to extract the section with `Stack Outputs` and parse it
@@ -336,7 +337,7 @@ class ServerlessFramework {
         const res = infoOutput.toString().match(/Stack Outputs:\n(( {2}[ \S]+\n)+)/);
         if (res) {
           try {
-            return YAML.load(res[1]);
+            return YAML.load(res[1], { schema: yamlSchema });
           } catch {
             // Pass to generic error
           }

src/configuration/read.js

@@ -5,6 +5,7 @@ const { createRequire } = require('module');
 const path = require('path');
 const fsp = require('fs').promises;
 const yaml = require('js-yaml');
+const yamlSchema = require('../utils/yaml-schema');
 const spawn = require('../utils/spawn');
 const ServerlessError = require('../serverless-error');
 
@@ -86,6 +87,7 @@ const parseConfigurationFile = async (configurationPath) => {
       try {
         return yaml.load(content, {
           filename: configurationPath,
+          schema: yamlSchema,
         });
       } catch (error) {
         throw new ServerlessError(

src/utils/yaml-schema.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const yaml = require('js-yaml');
+
+// Drop implicit timestamps so date-shaped plain scalars and mapping keys stay strings; an
+// explicit `!!timestamp` tag still constructs a Date
+const implicit = yaml.DEFAULT_SCHEMA.implicit.filter(
+  (type) => type.tag !== 'tag:yaml.org,2002:timestamp'
+);
+
+module.exports = new yaml.Schema({
+  implicit,
+  explicit: [...yaml.DEFAULT_SCHEMA.explicit, yaml.types.timestamp],
+});

test/unit/components/framework/index.test.js

@@ -196,6 +196,22 @@ describe('test/unit/components/framework/index.test.js', () => {
     expect(context.outputs).to.deep.equal({ Key: 'Output' });
   });
 
+  it('correctly handles refresh-outputs with date-shaped outputs', async () => {
+    const spawnStub = createSpawnStub(
+      createClassicSpawnResult({
+        stdout: 'region: us-east-1\n\nStack Outputs:\n  ReleaseDate: 2026-09-06',
+      })
+    );
+    const FrameworkComponent = loadFrameworkComponent(spawnStub);
+
+    const context = await getContext();
+    const component = new FrameworkComponent('some-id', context, { path: 'path' });
+    context.state.detectedFrameworkVersion = '9.9.9';
+    await component.refreshOutputs();
+
+    expect(context.outputs).to.deep.equal({ ReleaseDate: '2026-09-06' });
+  });
+
   it('correctly recognizes region in inputs', async () => {
     const spawnStub = createSpawnStub(createClassicSpawnResult({ stdout: INFO_OUTPUT }));
     const FrameworkComponent = loadFrameworkComponent(spawnStub);

test/unit/src/configuration/read.test.js

@@ -41,6 +41,18 @@ describe('test/unit/src/configuration/read.test.js', () => {
     });
   });
 
+  it('should keep date-shaped values as strings', async () => {
+    configurationPath = 'serverless-compose.yml';
+    await fsp.writeFile(
+      configurationPath,
+      'name: test-yml\nservices:\n  resources:\n    path: resources\n    params:\n      policyVersion: 2012-10-17\n'
+    );
+    expect(await readConfiguration(configurationPath)).to.deep.equal({
+      name: 'test-yml',
+      services: { resources: { path: 'resources', params: { policyVersion: '2012-10-17' } } },
+    });
+  });
+
   it('should read "serverless-compose.json"', async () => {
     configurationPath = 'serverless-compose.json';
     const configuration = {

test/unit/src/utils/yaml-schema.test.js

@@ -0,0 +1,20 @@
+'use strict';
+
+const expect = require('chai').expect;
+const yaml = require('js-yaml');
+const yamlSchema = require('../../../../src/utils/yaml-schema');
+
+const load = (input) => yaml.load(input, { schema: yamlSchema });
+
+describe('test/unit/src/utils/yaml-schema.test.js', () => {
+  it('keeps date-shaped plain scalars and mapping keys as strings', () => {
+    expect(load('date: 2012-10-17').date).to.equal('2012-10-17');
+    expect(load('dateTime: 2020-12-12T00:00:00Z').dateTime).to.equal('2020-12-12T00:00:00Z');
+    expect(load('spaced: 2020-12-12 00:00:00').spaced).to.equal('2020-12-12 00:00:00');
+    expect(load('map:\n  2012-10-17: value').map).to.deep.equal({ '2012-10-17': 'value' });
+  });
+
+  it('constructs a Date for an explicit timestamp tag', () => {
+    expect(load('date: !!timestamp 2020-12-12').date).to.be.instanceOf(Date);
+  });
+});