Summary

Create a unified error code registry document that catalogs all error code ranges across the ecosystem, verifies no overlaps, and provides a lookup reference.

Parent Issue

Part of: [EPIC] docs: Address documentation gaps across all ecosystem systems (#325)

Background (Why)

The kcenon ecosystem uses a decentralized error code registry where each system is allocated a range:

• common_system: -1 to -99
• thread_system: -100 to -199
• logger_system: -200 to -299
• container_system: -300 to -399
• monitoring_system: -400 to -499
• database_system: -500 to -599
• network_system: -600 to -699

However, there is no centralized document verifying:

• Actual error codes defined in each system
• Whether any codes overlap between systems
• What each specific error code means
• How to handle cross-system error propagation

Scope (What)

Create docs/ERROR_CODES.md covering:

1. Error Code Range Allocation

2. Per-System Error Code Catalog

For each system, list every defined error code:

-1: UNKNOWN_ERROR — General unknown error
-2: INVALID_ARGUMENT — Invalid function argument
...

3. Error Code Lookup

• How to look up error code meaning programmatically
• Error code to string conversion API
• Logging error codes with context

4. Cross-System Error Handling

• How errors propagate across system boundaries
• Error wrapping and context addition
• Best practices for multi-system error handling

5. Error Code Verification

• Script or test to verify no overlapping codes
• CI integration for error code uniqueness

Acceptance Criteria

• All error code ranges documented
• Actual used codes enumerated per system
• No overlapping codes verified
• Cross-system error handling patterns documented
• Verification script or test provided