Fix #1599: onDidChangePythonProjects never fires on runtime project a…

[Mohit Yadav (mohityadav8)]

Summary

Fixes #1599 — PythonEnvironmentApi.onDidChangePythonProjects never fired when projects were added or removed at runtime. The internal project list updated correctly, but the public event was never forwarded, so consumers (notably Pylance's per-folder interpreter support) never got notified and required a restart to pick up new projects.

Root cause

PythonEnvironmentApiImpl's constructor subscribed to environment-change events but never subscribed toprojectManager.onDidChangeProjects, so _onDidChangePythonProjects.fire(...) was never called.

Fix

• Added a previousProjects field on PythonEnvironmentApiImpl that tracks the last-known project set.
• Subscribed to projectManager.onDidChangeProjects in the constructor. On each internal change, compute the added/removed delta by diffing project URIs against the previous snapshot, update the snapshot, and fire _onDidChangePythonProjects with { added, removed } when the set actually changed.

Diffing by URI (rather than relying on the manager's internal eventpayload) was needed because the manager currently emits the full projectarray rather than a delta, and DidChangePythonProjectsEventArgs expectsadded/removed.

Testing

• npm run compile — clean build.
• Manually verified via getPythonProjects() that the set updates as expected; confirmed the new subscription fires on addPythonProject() and removePythonProject() calls.

[Mohit Yadav (mohityadav8)]

cc Eleanor Boyd (@eleanorjboyd)

[Eduardo Villalpando Mello (edvilme)]

Is there a reason we are exporting this?

[Mohit Yadav (mohityadav8)]

Hi Eduardo Villalpando Mello (@edvilme)! I exported PythonEnvironmentApiImpl so I could import and instantiate it directly in the new unit test file (src/test/features/pythonApi.unit.test.ts) to verify onDidChangePythonProjects. If you prefer a different factory/internal access pattern for unit testing this class, let me know and I'd be happy to adjust!

[Eduardo Villalpando Mello (edvilme)]

Hello Mohit Yadav (@mohityadav8) thanks for the contribution!! Everything looks great, but there are some linting issues around the use of any in TS. Once they get fixed, we can merge this! 😄

[Mohit Yadav (mohityadav8)]

Eduardo Villalpando Mello (@edvilme) thanks for review i have updated my pr now blint check is passing thanks for reviewing this

[Copilot]

Pull request overview

Fixes PythonEnvironmentApi.onDidChangePythonProjects not firing by wiring the internal project-manager change event through to the public API, computing an { added, removed } delta snapshot-to-snapshot so API consumers (e.g., Pylance) receive runtime project updates.

Changes:

• Subscribes PythonEnvironmentApiImpl to projectManager.onDidChangeProjects and fires onDidChangePythonProjects with computed added/removed deltas.
• Tracks a previousProjects snapshot to enable delta computation even though the manager emits a full project list.
• Adds a unit test validating the public event fires on project changes.

Show a summary per file

File	Description
src/features/pythonApi.ts	Wires internal project changes to the public API event and computes deltas via snapshot diffing.
src/test/features/pythonApi.unit.test.ts	Adds unit coverage for onDidChangePythonProjects event forwarding/delta behavior.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 3
• Review effort level: Low

[Mohit Yadav (mohityadav8)]

Eduardo Villalpando Mello (@edvilme) everthing is solved :D

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[Eleanor Boyd (eleanorjboyd)]

Mohit Yadav (@mohityadav8) could you take a look at the copilot comments- I agree that they are reasonable. Otherwise thanks so much for the contribution!

[Mohit Yadav (mohityadav8)]

Mohit Yadav (@mohityadav8) could you take a look at the copilot comments- I agree that they are reasonable. Otherwise thanks so much for the contribution!

Solved copilot review in e14f6e4

[Eduardo Villalpando Mello (edvilme)]

Thanks so much for your contribution and fixes. PR looks good to me! :D