fix: keep deployments backend optional

[svvarom]

The Automodel nightly image build fails while validating its reduced uv workspace because nmp-models declares nemo-deployments-plugin as a required workspace dependency even though that backend is loaded lazily. This removes the accidental required edge, refreshes the lockfile, and adds regression coverage for all reduced Docker workspaces so the normal uv sync --package nmp-models path works again.

Failure: Platform-Deploy run 29388161869

This is the root-contract alternative to #697: it keeps dependency resolution enabled instead of installing nmp-models with --no-deps.

Human attention needed

• Decision: confirm the deployments plugin is optional for nmp-models and should be installed through the platform plugin profile when enabled
• Read carefully: services/core/models/pyproject.toml and the optional-dependency assertion
• Safe to skim: the two-line uv.lock update
• Proof: focused tests, lint/format checks, bake graph, and the exact private Docker build all pass
• Biggest risk: a consumer may have relied on installing bare nmp-models to pull the deployments plugin implicitly

Evidence

• uv lock --check
• pytest tests/unit/test_docker_workspace_slices.py services/core/models/tests/unit/controllers/test_backend_registry.py (5 passed)
• ruff check and ruff format --check on the new test
• BUILD_ARCH=linux/amd64 make docker-print TARGET=nmp-automodel-tasks-docker
• Platform-Deploy run 29429138807 passed the full Automodel, Unsloth, and RL bake plus both Automodel smoke targets against commit 39d915c22a6335d189810e7e22c4990145dc7e89.

[coderabbitai]

📝 Walkthrough

Walkthrough

The models service removes nemo-deployments-plugin from unconditional dependencies and workspace sources. New tests validate workspace-source coverage for Docker slices and ensure the deployments plugin remains optional.

Changes

Models workspace dependencies

Layer / File(s)	Summary
Remove optional deployments dependency services/core/models/pyproject.toml	Removes nemo-deployments-plugin from dependencies and tool.uv.sources.
Validate workspace slice consistency tests/unit/test_docker_workspace_slices.py	Adds helpers and regression tests covering workspace-source membership across Docker slices and the models plugin declaration.

Possibly related PRs

• NVIDIA-NeMo/nemo-platform#663: Adds the deployments plugin backend and reintroduces its workspace dependency in the models service.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: keeping the deployments backend optional.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/automodel-workspace-contract

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[github-actions]

Suite	Lines Covered	Line Rate	Branch Rate
Unit Tests	25439/32661	77.9%	62.5%
Integration Tests	14703/31310	47.0%	19.3%