fix(ui): redirect pre-refactor CoSTEER module path so old demo_traces deserialise

[genisis0x]

Summary

• Closes ModuleNotFoundError : No module named 'rdagent.components.coder.factor_coder.CoSTEER'' #1331. The `demo_traces` archive linked from the README was pickled when CoSTEER lived at `rdagent.components.coder.factor_coder.CoSTEER`. After the refactor relocated it to `rdagent.components.coder.CoSTEER`, opening those traces in `rdagent ui` fails with `ModuleNotFoundError: No module named 'rdagent.components.coder.factor_coder.CoSTEER'`. Current maintainer guidance is to roll back to a legacy commit just to view the demo, which is a steep ask for a feature the README advertises front and center.
• Install a `sys.meta_path` finder in `rdagent/components/coder/factor_coder/_costeer_compat.py` that transparently redirects imports under `rdagent.components.coder.factor_coder.CoSTEER[.]` to the matching submodule under `rdagent.components.coder.CoSTEER[.]`. The redirector is registered as the first thing `rdagent.components.coder.factor_coder.init` does, so any pickle loaded after `rdagent` is imported (which `rdagent ui` does at startup) can resolve the old path.

Why this approach

• A meta-path finder is the smallest possible change that handles every submodule the old pickles might reference, including ones we haven't touched yet, without needing stub `.py` files mirroring the entire pre-refactor tree.
• The finder only matches the specific old prefix and falls through for every other import, so it cannot mask unrelated `ModuleNotFoundError`s.
• Already-imported submodules are reused from `sys.modules`; uncached submodules are imported lazily via `importlib.import_module`.

Tests

`test/utils/coder/test_costeer_path_compat.py` covers:

• the old package path resolves to the same module object as the new one
• each of the relocated submodules (`evaluators`, `evolving_strategy`, `knowledge_management`, `task`, `config`) resolves identically
• a pickle whose recorded `module` points at the old path round-trips successfully after the old-path entries are dropped from `sys.modules` to simulate a fresh process

Checklist

• Issue linked
• Tests added
• No behavioural change for users who already imported via the new path
• CLA will be confirmed in a follow-up comment

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📚 Documentation preview 📚: https://RDAgent--1413.org.readthedocs.build/en/1413/

[genisis0x]

Read the CLA — all clear from my side.

@microsoft-github-policy-service agree