Complete a partially implemented feature by filling gaps and ensuring production readiness.

## Steps


1. Assess the current state of the feature:
2. Identify remaining work:
3. Complete each missing piece:
4. Harden the implementation:
5. Write missing tests and verify coverage.
6. Update documentation:
7. Run the full test suite and fix any regressions.

## Format


```
Feature: <name>
Completion Status: <before>% -> <after>%
Gaps Filled:
  - <gap>: <what was added>
```


## Rules

- Treat incomplete features as bugs that need fixing.
- Focus on making the feature shippable, not perfect.
- Every public API must have error handling and validation.