[simonvanlierde]

Hi Bernhard,

As you suggested in #1745, AB now fetches the template catalogue from files.brightway.dev once per session instead of on every project switch. On a slow connection, every switch waited for that request on the main thread.

• fetch_remote_projects() is now cached for the session with lru_cache. ProjectManagerSettingsChapter.sync called it every time, which means every project switch and every Save, Cancel and Restore Defaults in Settings. A failed fetch is cached too, so the list stays empty until you refresh.
• There's a new "Refresh remote templates" entry in the right-click menu of the Templates tab (Settings > Projects). I left it out of the top menu, since Project > Manage projects already leads there.
• ProjectNewTemplateMenu (Project > New > Import from template) now rebuilds when it opens, so it picks up a refresh. Templates made with "Create template from project" now also show up there without a restart.

With bw2io's request faked to take 2 s, a project switch took 4.2 s on major and 0.23 s with this change. The test setup keeps two Settings pages alive, so it makes two requests per switch; the app makes one, so expect about half that saving there. I haven't measured it in the real app.

Tests: 2 new tests in tests/test_remote_templates.py (no network, bw2io is faked). Full suite on Python 3.12, Linux, offscreen: 470 passed, 2 skipped, 1 failed. The failure is test_database_delete_multiple ("QAbstractEventDispatcher already deleted" in DatabaseOpen.run), and it fails the same way on major in my setup, so it's not from this change. I couldn't try Windows or macOS.

Checklist

• Keep pull requests small so they can be easily reviewed.
• Update the documentation (only the docstring changed; no wiki page covers templates)
  • For in-code documentation, please follow the numpy style guide.
  • For user documentation, please update the wiki in
    ./activity_browser/docs/wiki
• Update tests.
• Link this PR to related issues by using closing keywords. ("Refs", since Two proposals: check online templates once, and add tests that pin calculation results #1745 has a second point, answered in the issue)

If you have write access (otherwise a maintainer will do this for you):

• Categorize the PR by setting a good title and adding one of the labels:
  bug, feature, ui, change, documentation, breaking, ci
  as they show up in the changelog. (no write access)
• Add a milestone to the PR (and related issues, if any) for the intended release. (no write access)
• Request a review from another developer. (no write access)

Refs #1745

Best,

Simon