[foundation] activator skips reinstall when a module's source changes, so a repointed module keeps running the old editable checkout

[Joi]

Summary

amplifier_foundation/modules/activator.py skips the editable install of a module whenever a distribution with the same name is already installed in the tool venv (Package '<name>' already installed from wheels, skipping editable install from <path>). The check keys only on the distribution name. It does not compare the requested module path with where the installed distribution actually lives. So after a module's source is repointed (a sources.modules.<id> override in settings, a bundle behavior's source: line, or a removed pin), the old editable checkout keeps running on every host that installed the module before the change. Nothing in a run's output says so.

Repro

1. amplifier with a bundle whose hooks-routing source is fork A. Run once. The venv now has _editable_impl_amplifier_module_hooks_routing.pth -> ~/.amplifier/cache/<fork-A>/modules/hooks-routing.
2. Change the source to upstream B (settings sources.modules.hooks-routing, or the bundle file). Run again.
3. uv pip list --python ~/.local/share/uv/tools/amplifier/bin/python | grep hooks-routing still shows the fork-A path. Log: Package 'amplifier-module-hooks-routing' already installed from wheels, skipping editable install from ~/.amplifier/cache/<upstream-B>/modules/hooks-routing.
4. uv pip uninstall --python <venv python> amplifier-module-hooks-routing, run again. Now the .pth points at upstream B.

Versions: amplifier 2026.09.08-dfa56a7, amplifier-core 1.6.1, amplifier-foundation 1.0.0 (activator.py around lines 596-612, the _distribution_installed(pkg_name) guard; the same guard exists at ~397 in activate_bundle_package).

What it cost us

One Mac ran a fork of hooks-routing from June for three months after the fork override was superseded. That fork predates the model_role_resolver capability, so every recipe step with model_role: and every delegate(model_role=...) logged "no model_role_resolver capability is registered" and fell back to the default provider. The bundle and settings both said upstream. The same happened to tool-recipes after a fork pin was removed; the recipes engine's own provenance guard (engine_provenance.py, "editable install ... points at X but this engine was imported from Y") is what finally made it visible.

Suggestion

Keep the name-based skip for packages that came from PyPI wheels (that is the #326 case). For editable installs, compare the installed distribution's direct_url.json / .pth target with the module path being activated and reinstall when they differ. At minimum, log at WARNING when the requested path and the installed editable location disagree, so a repointed source is not silent.

[Joi]

A second shape of the same skip, seen on three Macs this week: the module's cache directory is deleted, not repointed, and the venv keeps the old editable install.

When a module's source URL or content changes, the cache path rotates to a new hash (~/.amplifier/cache/amplifier-module-provider-openai-<newhash>) and the old directory goes away. The .pth written by the earlier uv pip install -e still names the old directory. The next run resolves the module, sees the distribution is installed, and skips the install. Import then fails, and every headless run logs

Module 'provider-openai' not found in prepared bundle.

and continues without the provider. Nothing else says anything. On one machine provider-openai, provider-gemini and provider-github-copilot were all in this state.

Diagnostic:

cd ~/.local/share/uv/tools/amplifier/lib/python3.*/site-packages
for p in _editable_impl_amplifier_module_*.pth; do
  t=$(head -n1 "$p"); [ -d "$t" ] || echo "STALE $p -> $t"
done

Fix, per stale distribution: uv pip uninstall --python ~/.local/share/uv/tools/amplifier/bin/python <dist>, then run amplifier once. With nothing installed under that name the activator installs from the live cache directory. Rewriting the .pth by hand is not equivalent: it leaves direct_url.json pointing at the old directory.

The same check before skipping would cover both shapes: if the installed distribution's direct_url.json root is not the module path just resolved, or does not exist, reinstall instead of skipping.