Salesforce Winter '27 Developer Features: Apex, LWC, AI

The Salesforce Winter '27 release brings a suite of powerful features and enhancements targeted at developers, aiming to improve performance, development efficiency, and AI integration. This update focuses on increasing resource limits, streamlining testing, and providing richer metadata access.

Key Developer Features in Salesforce Winter '27

1. Increased Apex Heap Limits

Salesforce has significantly increased the heap limits for Apex transactions. This addresses a common pain point for developers dealing with larger datasets in production environments.

• Synchronous Transactions: Increased to 10MB (from 6MB).
• Asynchronous Transactions: Increased to 25MB (from 12MB).

This substantial increase (66% for synchronous, 108% for asynchronous) will help mitigate heap overflow errors. The "Enforce the Summer ‘26 Apex heap limit" setting will become effectively obsolete as these new limits are globally enforced.

Developers can check current heap limits using Limits.getLimitHeapSize() in Apex.

2. Test External Services and HTTP Callouts in Apex Integration Tests (Developer Preview)

This new developer preview feature allows for more robust integration testing by enabling direct testing of external services and HTTP callouts within Apex integration tests. This moves beyond mock callouts to validate interactions with real service responses.

Configuration:

• Enable ApexIntegrationTests in your scratch org's definition file.
• Annotate the integration test class and relevant test methods with @IntegrationTest.

Considerations:

• Integration tests forgo automatic rollback; you must manage your test data lifecycle.
• Use @BeforeClass to set up shared test data and @TearDown to clean up committed data.
• Only one concurrent integration test can run, and it must execute asynchronously.

Refer to the official release notes for sample code demonstrating data setup and teardown with @BeforeClass and @TearDown.

3. Apex Symbol API for Richer Development Tools (Beta)

The Apex Symbol API is a new Tooling API REST resource that provides detailed metadata about Apex types. This is a significant step towards improving developer tooling, particularly for code completion in IDEs and providing context for AI agents.

• Benefits: Powers IDE code completion, provides context for AI agents, and supports AI grounding for Apex code queries.
• Functionality: Bridges the gap between the /completions endpoint and the SymbolTable Tooling API object, offering a single source of truth for Apex type information.
• Use Case: Enables the creation of more accurate AI tools that can generate executable code rather than hallucinated results.

Sample code is available in the release notes for reference.

4. Complex Template Expressions in Lightning Web Components (Generally Available)

Complex JavaScript expressions are now generally available for use within LWC HTML template files, building upon the beta introduction in Spring ‘26.

• Functionality: Allows a broad subset of JavaScript expressions directly within templates, enabling more dynamic component rendering.
• Benefits: Reduces the need for numerous getters solely for data formatting or CSS class construction, and simplifies handling iterations by allowing data binding directly in the template.
• Opt-in: Supported from LWC version 66.0 or later, configured in the .js-meta.xml file.

5. Use Third-Party Web Components in LWC (Generally Available)

Salesforce now supports the integration of third-party web components directly into LWCs, eliminating the need for workarounds like iframes or manual library management.

• Implementation: Apply the lwc:external directive to an element in your LWC template.
• Benefits: Saves development time and reduces code maintenance by leveraging existing, standards-compliant web components.
• Underlying Technology: Built on web standards, enabling seamless integration.

6. Salesforce Development Claude Code Plugin

A dedicated Claude code plugin for Salesforce development aims to improve the accuracy and effectiveness of AI coding assistants by providing them with Salesforce DX project context and org context.

• Functionality: Detects Salesforce DX projects and uses hosted MCP servers for org context.
• Benefit: Grounds AI models like Claude, leading to more accurate code suggestions and reducing the incidence of AI-generated errors specific to the Salesforce platform.
• Target Audience: Useful for both experienced Salesforce developers and those less familiar with the platform asking questions about code.

7. Compare Values Between Fields in SOQL (Beta)

This beta feature introduces the FORMULA() function within SOQL WHERE clauses, allowing for direct comparison and calculation between fields.

• Functionality: Enables the creation of inline formulas within SOQL queries.
• Benefits: Eliminates the need for formula fields or extensive Apex processing for simple data filtering, saving time and resources.
• Example:

  SELECT Id, Name FROM Opportunity WHERE FORMULA('Amount_To_Pay__c - Amount_Paid__c') > 0
  

• Availability: Beta in Winter ‘27, requires API version 68.0+, and is not available in production environments.

8. Simplify REST API Version Management

Developers can now use the latest keyword in REST API URIs to automatically reference the most recent API version, simplifying integration maintenance.

• Usage: Replace the specific version number (e.g., v66.0) with latest in your API endpoint.
• Example:

  https://<MyDomainName>.my.salesforce.com/services/data/latest/sobjects/Account
  

• Benefit: Reduces the frequency of integration updates required for API version changes.

9. Resolve Field Name Conflicts in Managed Package SOQL Queries

This feature addresses a common challenge for Independent Software Vendors (ISVs) by allowing them to resolve potential field name conflicts in SOQL queries within managed packages. This enhancement aims to prevent issues where subscriber custom fields might clash with package field API names.

Key Takeaways

• Increased Performance: Higher Apex heap limits and LWC template expression improvements boost runtime efficiency.
• Enhanced Testing: Apex integration tests now support direct callout validation for more reliable code.
• AI-Native Development: The Apex Symbol API and Claude code plugin facilitate the development of smarter, context-aware AI tools for Salesforce.
• Simplified Integrations: Using latest in REST API URIs and the FORMULA() function in SOQL reduce development and maintenance overhead.
• ISV Support: New capabilities for resolving field name conflicts benefit managed package developers.