[module-resolution] AMPLIFIER_MODULE_<ID> env override honored by inspection commands but not session activation

Component: module resolution (amplifier-app-cli, amplifier-foundation — both have Issues disabled, filed here)

Setting AMPLIFIER_MODULE_PROVIDER_ANTHROPIC=/path/to/local/checkout:

Current behavior:

• amplifier module show provider-anthropic correctly displays the override source (code: commands/module.py:65,217,426; source.py:586)
• amplifier run executes the stock installed/cached package with the same env var set

How we know:
Verified via request-param A/B test: both live sessions emitted identical requests with the same env var set; the override path's code demonstrably did not run.

Related issues (same class of problem):

1. #342: auto-repair clobbers pinned installs after install-time gates pass
2. (This issue) env var override honored by inspection, not activation
3. config.providers[].source recorded in mount plans but ignored at activation

The pattern:
Three documented override surfaces, none of which control executed code when a package is already installed. Mount plans and inspection commands record intent, not code identity.

Ask:
Module activation must consult the same override ladder that inspection commands use — or the docs must stop claiming per-session env overrides work.

Related PRs:

• microsoft/amplifier-module-provider-anthropic#76 (canonical reasoning_effort key for anthropic)
• microsoft/amplifier-module-provider-openai#55 (canonical reasoning_effort key for openai)
• microsoft/amplifier-foundation#282 (SHA-ref support for reproducible bundle pinning)

Cross-references microsoft/amplifier#342.

Start with commands/module.py and source.py:586, comparing the override ladder used by module inspection with the path taken by amplifier run during session activation. Reproduce the request-parameter A/B test with AMPLIFIER_MODULE_PROVIDER_ANTHROPIC pointing to a local checkout. Done means activation executes the override code, not the installed or cached package, while inspection and activation agree.