[WIP] Define protocol interface evolution strategy for connector contracts

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Architecture: Protocol Interface Evolution</issue_title>
<issue_description>## Summary
Define a protocol interface evolution strategy for connector contracts to ensure backward compatibility as APIs evolve.

Architecture Decision

Enterprise APIs change over time. The connector architecture must:

• Support multiple API versions simultaneously
• Enable gradual migration between versions
• Maintain backward compatibility for consumers
• Provide clear deprecation paths

Version Strategy

• Protocol Versioning: PIMConnectorProtocol_v1, v2
• Adapter Pattern: Version-specific adapters behind common interface
• Feature Flags: Enable new capabilities incrementally
• Response Transformation: Normalize across versions

Migration Patterns

1. Add new version alongside existing
2. Mark old version deprecated
3. Migrate consumers
4. Remove old version after grace period

Implementation Location

connectors/common/versioning.py
connectors/common/protocols_v2.py (future)

Tasks

• Design versioning strategy for protocols
• Implement version negotiation
• Create adapter wrappers for version translation
• Add deprecation logging
• Document migration procedures
• Write compatibility tests

References

• connectors/common/protocols.py
• Semantic versioning best practices
  </issue_description>

<agent_instructions>Follow the Architecture_Patterns agent instructions in .github/agents/Architecture_Patterns.agent.md</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Custom agent used: Architecture_Patterns
Implements architecture patterns: Connector Registry, Event-Driven Sync, Multi-Tenant Config, Protocol Evolution, Data Guardrails, and Reference Architectures (Issues #79-#84)

• Fixes Architecture: Protocol Interface Evolution #82

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[Cataldir]

Rebase sync update: this PR branch has been rebased onto current main (8c05ea9) after #145 merge. Please trigger any final validation you want before review/merge.