Project Memory - Smartdata

TC39 Decorator Migration (v6.0.0) - ✅ COMPLETED

Final Status: All Tests Passing (157/157)

Migration successfully completed on 2025-11-17.

What Changed:

✅ Removed experimentalDecorators from tsconfig.json
✅ Refactored all 7 decorators to TC39 Stage 3 syntax
- 5 property decorators: @globalSvDb, @svDb, @unI, @index, @searchable
- 2 class decorators: @Collection, @managed
✅ Implemented context.metadata pattern for shared decorator state
✅ All tests passing across Node.js and Deno runtimes

Critical Discovery: TC39 Metadata Access Pattern

THE KEY INSIGHT: In TC39 decorators, metadata is NOT accessed via constructor[Symbol.metadata]. Instead:

Field decorators: Write to context.metadata
Class decorators: Read from context.metadata (same shared object!)
The context.metadata object is shared between all decorators on the same class
Attempting to write to constructor[Symbol.metadata] throws: "Cannot assign to read only property"

Implementation Pattern:

// Field decorator - stores metadata
export function svDb() {
  return (value: undefined, context: ClassFieldDecoratorContext) => {
    const metadata = context.metadata as ISmartdataDecoratorMetadata;
    if (!metadata.saveableProperties) {
      metadata.saveableProperties = [];
    }
    metadata.saveableProperties.push(String(context.name));
  };
}

// Class decorator - reads metadata and initializes prototype
export function Collection(dbArg: SmartdataDb) {
  return function(value: Function, context: ClassDecoratorContext) => {
    const metadata = context.metadata as ISmartdataDecoratorMetadata;
    if (metadata?.saveableProperties) {
      decoratedClass.prototype.saveableProperties = [...metadata.saveableProperties];
    }
    return decoratedClass;
  };
}

Runtime Compatibility:

✅ Node.js v23.8.0: Full TC39 support
✅ Deno v2.5.4: Full TC39 support
❌ Bun v1.3.0: No TC39 support (uses legacy decorators only)
- Removed "+bun" from test filenames to skip Bun tests

Key Technical Notes:

Metadata Initialization Timing: Class decorators run AFTER field decorators, allowing them to read accumulated metadata and initialize prototypes before any instances are created
Prototype vs Instance Properties: Properties set on prototype are accessible via this.propertyName in instances
TypeScript Lib Support: TypeScript 5.9.3 includes built-in decorator types (no custom lib configuration needed)
Interface Naming: Used ISmartdataDecoratorMetadata extending DecoratorMetadataObject for type safety

Files Modified:

ts/classes.doc.ts (property decorators + metadata interface)
ts/classes.collection.ts (class decorators + prototype initialization)
tsconfig.json (removed experimentalDecorators flag)
test/*.ts (renamed files to remove "+bun" suffix)

Test Results:

All 157 tests passing across 10 test files:

test.cursor.ts: 7/7
test.deno.ts: 11/11 (queries working correctly!)
test.search.advanced.ts: 41/41
test.typescript.ts: 4/4
test.watch.ts: 5/5
And 5 more test files

Migration Learnings for Future Reference:

context.metadata is the ONLY way to share state between decorators
Class decorators must initialize prototypes from metadata immediately
Symbol.metadata on constructors is read-only (managed by runtime)
Field decorators run before class decorators (guaranteed order)
TypeScript 5.2+ has built-in TC39 decorator support

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