• Convert existing null TenantId values to empty strings for default tenant data in WorkflowDefinitions, WorkflowInstances, and runtime entities.
• Review ADR-0008 (Default Tenant ID) and ADR-0009 (Tenant-Agnostic Entities) in doc/adr/ for detailed rationale and migration guidance.

Query filter changes: EF Core query filters have been updated to handle the new tenant ID conventions, ensuring tenant isolation is properly maintained. (7bc9035f5) (#7226)

✨ New features

Multitenancy enhancements

• Configuration-based multitenancy: Introduced configuration-based tenant provider to streamline tenant initialization and customization. (b09a56481) (#7217)
• Tenant-agnostic workflow support: Workflows and activities can now be marked as tenant-agnostic (using "*" as tenant ID) to make them accessible across all tenants. (7bc9035f5) (#7226)
• Selective lock mocking in tests: Added SelectiveMockLockProvider for precise lock mocking in tests without affecting unrelated background operations. (b09a56481) (#7217)

🔧 Improvements

Multitenancy

• Tenant filtering in workflow store populator: Added tenant-specific filtering in DefaultWorkflowDefinitionStorePopulator to ensure workflows are only loaded for the current tenant. (b09a56481) (#7217)
• Tenant isolation in activity provider: Enforced tenant isolation in WorkflowDefinitionActivityProvider and included tenant ID in activity type names for better separation. (558902bb7)
• Optimized activity registry: Improved ActivityRegistry.Find to prefer tenant-specific descriptors over tenant-agnostic ones with single-pass iteration for better performance. (7bc9035f5) (#7226)
• Tenant headers support: Added tenant headers support to BackgroundWorkflowCancellationDispatcher for proper tenant context propagation during workflow cancellation. (bc70beff1) (#7040)

API improvements

• Labels endpoints migration: Updated Labels endpoints to use ElsaEndpoint base class with standardized permission configuration. (72569702f) (#7205)

Error handling

• Graceful ParentInstanceId handling: Enhanced ResumeBulkDispatchWorkflowActivity to gracefully handle missing ParentInstanceId values. (641dd664d)
• Improved async handling: Enhanced async handling in CommandHandlerInvokerMiddleware to properly await tasks without blocking. (7bc9035f5) (#7226)
• Enhanced logging for recurring tasks: Added error handling and logger support to prevent crashes in scheduled timers. (7bc9035f5) (#7226)

🐛 Fixes

• Synthetic inputs exception handling: Fixed uncaught exception thrown in ReadSyntheticInputs when workflow inputs have reserved names like 'Metadata'. Now collects exceptions and returns them to the caller with a valid IActivity instance instead of breaking the publishing loop. (4cd2c4cda, b8228351a) (#7199)
• Memory leak in compression: Fixed memory leak by properly disposing IronCompressResult in Zstd codec implementation. (05d40e3a2) (#7193)
• Default tenant data visibility: Fixed data visibility leak by removing NullIfEmpty conversion to properly distinguish between default tenant ("") and tenant-agnostic ("*") entities. (7bc9035f5) (#7226)

🧪 Tests

• Reserved keywords documentation: Added unit tests to document and verify reserved keywords in workflow inputs (e.g., CustomProperties, Metadata). (ffd4327d2) (#7180)
• Tenant ID normalization tests: Added comprehensive unit tests for tenant ID normalization covering null, empty, and valid ID scenarios. (b09a56481) (#7217)
• Multitenancy pipeline tests: Added tests for multitenancy pipeline invoker covering various tenant resolution scenarios. (b09a56481) (#7217)
• Activity registry tests: Added extensive tests for ActivityRegistry to verify tenant-specific and tenant-agnostic descriptor handling. (7bc9035f5) (#7226)
• Compression codec tests: Added tests for Zstd codec compression and decompression to prevent memory leaks. (05d40e3a2) (#7193)
• Workflow deletion tests: Enhanced DeleteWorkflowTests with signal-based waiting and improved registry refresh verification. (641dd664d, 25bf37705, cc3a2c2c0, afe33baf0)
• Activity construction tests: Improved test coverage for ActivityConstructionResult and exception handling scenarios. (b09a56481) (#7217)
• Workflow store populator tests: Expanded test coverage for DefaultWorkflowDefinitionStorePopulator with tenant-specific scenarios. (b09a56481) (#7217)

📖 Documentation

• Architecture Decision Records: Added multiple ADRs documenting multitenancy design decisions:
  • ADR-0008: Empty string as default tenant ID (⚠️ breaking)
  • ADR-0009: Asterisk as tenant-agnostic sentinel value (⚠️ breaking)
  • (b09a56481, 7bc9035f5) (#7217, #7226)

📦 Full changelog

Commits not covered above:

• Remove duplicate reference to tenant-deleted-event ADR in solution file. (af1e4e835)
• Remove unused variables in synthetic input handling. (a69d44794)
• Apply code review suggestions from @sfmskywalker. (b0b2080a3)
• Refactor obsolete class handling to avoid contract changes. (b3d155de6)

🙏 Contributors

Special thanks to all contributors to this release:

• @sfmskywalker
• Community contributors who reported issues and provided feedback

Note: This is a release candidate. Please report any issues on GitHub Issues.