Reorganize Collab examples by difficulty

[holgerroth]

What changed

• Moved the self-contained NumPy Collab introduction to examples/hello-world/hello-collab/.
• Moved hello_fedavg, simple_split_learning, async aggregation, and swarm to examples/advanced/collab/ while preserving their shared collab package layout.
• Updated example catalogs, design documentation, run commands, links, and unit-test import paths for the new tiered locations.

Why

NVFlare already tiers examples by difficulty. Putting the minimal Collab workflow beside hello-numpy makes the recommended custom-workflow path visible where new users start, while keeping the more specialized response-callback, split-learning, and decentralized workflows in the advanced tier.

The hello example is already self-contained in one file, so it does not depend on the shared advanced package context.

Validation

• pytest tests/unit_test/collab/examples_test.py -q — 2 passed
• Collab example/public-import/runtime targeted suite — 16 passed
• Relocated simple_split_learning import and recipe finalization — passed
• ./runtest.sh -s --skip-install — Black, isort, flake8, and agent-skill lint passed
• ./build_doc.sh --html --skip-api — Sphinx HTML build passed
• git diff --check

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.28%. Comparing base (3244fa3) to head (1b77db7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4960   +/-   ##
=======================================
  Coverage   64.28%   64.28%           
=======================================
  Files        1030     1030           
  Lines      103739   103739           
=======================================
+ Hits        66686    66693    +7     
+ Misses      37053    37046    -7     

Flag	Coverage Δ
unit-tests	64.28% <ø> (+<0.01%)	⬆️

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[nvidianz]

Notice the unit test for collab example. I think that's too much, should we remove it?

[holgerroth]

@nvidianz Good point — agreed that asserting example behavior is testing documentation. Pushed 3f91cc7:

• Removed the numpy training-math assertions and the example-level torch-block subprocess test.
• Kept a deliberately minimal smoke layer: one parametrized test that imports each cataloged example and checks make_recipe().finalize() returns a job. That isn't really testing the examples — it's the cheapest alarm for API drift, since the catalog is the first thing users run against a still-new API (the blob_cb regression in Add simple Collab split learning example #4958 passed all runtime unit tests and only surfaced when an example was actually run).
• The torch-free base-install constraint the removed test carried now lives fully at the library level: test_collab_public_surface_does_not_require_torch additionally imports CollabRecipe.

If you'd rather have zero pytest coupling to examples, I'd swap the smoke layer for a CI step that runs hello_numpy_collab end-to-end in SimEnv (numpy-only, finishes in seconds) — happy to do that as a follow-up.

[greptile-apps]

Greptile Summary

Reorganizes Collab examples by difficulty.

• Moves the self-contained NumPy introduction into the hello-world catalog.
• Relocates specialized Collab workflows under advanced examples.
• Updates documentation, commands, links, requirements, and smoke-test import paths for the new layout.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
examples/hello-world/hello-collab/job.py	Relocates the introductory Collab workflow into a directly runnable hello-world script.
examples/advanced/collab/README.md	Updates the advanced Collab catalog, execution commands, and documentation links for its new location.
tests/unit_test/collab/examples_test.py	Updates recipe-finalization smoke tests to import examples from their reorganized locations.
tests/unit_test/collab/public_imports_test.py	Extends the torch-free public-surface check to import CollabRecipe explicitly.

_{Reviews (9): Last reviewed commit: "Merge branch 'main' into feat/reorganize..." | Re-trigger Greptile}