Add opt-in refreshExtensionOnPackagesChange to restart the language server on package changes

[Copilot]

Summary

Adds an opt-in ToolConfig.refreshExtensionOnPackagesChange key that restarts the language server whenever the active Python environment's package managers report a package change (install/uninstall). The behavior is wired through the shared activation logic and is off by default, so existing extensions are unaffected until they opt in.

Changes

• types.ts — new optional ToolConfig.refreshExtensionOnPackagesChange boolean (defaults to false).
• activation.ts — when the key is true, initializePython is given a callback that restarts the language server (safeRunServer, same path as config/interpreter changes) on each package change.
• python.ts — IPythonApi exposes an onDidChangePackages subscription. The newer ms-python.python-environments adapter forwards the extension event; the legacy ms-python.python adapter is a no-op since it does not emit package events. The automatic refresh wiring (the callback that restarts the server) stays internal to activation.
• Tests — activation.test.ts covers the enabled (callback restarts server) and disabled (no callback) paths; python.test.ts confirms initializePython accepts the optional callback.
• Docs — README and CHANGELOG updated.
• Version — bumped to 0.8.0.

Validation

• npm run build — clean
• npm test — 127 passing

[edvilme]

Related: microsoft/vscode-python-environments#1597

[rchiodo]

Solid, well-scoped opt-in feature. The main thing to resolve before merge is that the package-change subscription is only wired when the Python extension resolves the interpreter — pinning an interpreter via setting makes refreshExtensionOnPackagesChange: true silently do nothing. Either wire it in both paths or document the limitation. A few smaller hardening/test items are noted inline.

[rchiodo]

Solid, well-scoped opt-in feature. The main thing to resolve before merge is the pinned-interpreter dead zone: when <serverId>.interpreter is set, initializePython is never called, so refreshExtensionOnPackagesChange: true does nothing and nothing tells the user. Either wire the subscription independently of how the interpreter was resolved (mirroring the onDidChangeInterpreter pattern in registerCommonSubscriptions) or document the limitation. Also worth hardening: don't let the refresh subscription run before refreshServerPython(), and add a real integration test for the one wiring line.

[edvilme]

Thanks for the thorough review! Addressed in 4cb83cb:

• Pinned-interpreter blocker — the package subscription is now wired in initialize() after interpreter resolution in both paths (extension-resolved and pinned via <serverId>.interpreter), so refreshExtensionOnPackagesChange: true is never silently inert.
• Non-fatal subscription — moved into a dedicated PythonEnvironmentsProvider.subscribeToPackageChanges() that guards typeof onDidChangePackages and try/catches, returning undefined on failure. It can no longer block interpreter resolution or server startup.
• Debounce — added a trailing-edge debounce around the package trigger to collapse bursty installs. Active-environment filtering is deferred pending the richer event payload (Add site-packages watchers vscode-python-environments#1597).
• Tests — real subscription test (fake API + fired event), pinned-path coverage, and rewrote the activation test to await an observable restart signal instead of counting macrotasks.
• Lock hygiene — reverted the incidental "peer": true drift; the lock diff is now just the version bump.

npm run build, npm run lint, and npm test (131 passing) all green.

[rchiodo]

Looks good. Note that most of the carried-over 'unresolved' findings no longer apply to this revision: the subscription is now a standalone subscribeToPackageChanges method wired after interpreter resolution (so it works for pinned interpreters too, with a test to prove it), a trailing-edge triggerPackageRefresh debounce was added, and the tests now inject a fake API / await an observable signal rather than relying on getApi() returning undefined or flushing macrotasks. Only two small non-blocking items below.

[rchiodo]

Approved via Review Center.