Add ADR for ModelCollection design (PR #180)

[Copilot]

Documents the architectural decision to introduce ModelCollection, a new base class combining MutableSequence with EasyScience features for managing collections of model objects.

Structure

• docs/adr/ - Markdown ADRs for GitHub viewing
• docs/src/adr/ - RST versions integrated with Sphinx documentation
• docs/src/index.rst - Added "Architecture" section to main docs

ADR-0001 Content

Context: No dedicated collection class existed that provided list operations while maintaining interface propagation, graph tracking, and serialization.

Decision: ModelCollection(ModelBase, MutableSequence[T]) with:

• Automatic interface propagation to contained items
• Graph edge management for dependency tracking
• Type-safe access by index, slice, or name
• 278 LOC implementation, 102 tests

Key Design Choices:

• Dual inheritance over composition for standard list semantics
• _add_item/_remove_item helpers for graph consistency
• TypeVar generics and @overload for IDE support

Trade-offs: Unified API and type safety vs. additional complexity and memory overhead for graph tracking.

Status: Proposed (PR #180 is draft/open)

# Enables patterns like:
collection = ModelCollection(model1, model2, model3, interface=calc_interface)
collection[0]  # by index
collection['model_name']  # by name
collection.append(model4)  # interface auto-propagates

Future Maintenance

Status should be updated to "Accepted" when PR #180 merges.

Original prompt

Create an ADR proposal based on this draft pull request (#180 - New collection base)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.