feat(sglang): add managed Python sidecar entrypoint

[connorcarpenter15]

Summary

• Replace the top-level dynamo.sglang_sidecar module with the SGLang-scoped dynamo.sglang.sidecar entry point.
• Move the native launcher to the private dynamo._core.backend._run_sglang_sidecar(argv) binding.
• Preserve ordinary Python argument semantics by prepending the executable name before clap parses the arguments.
• Release the GIL while bootstrapping and running Dynamo's unified worker lifecycle.
• Configure Dynamo logging only when main() runs, not when the module is imported.
• Add binding and Python launcher coverage.

Motivation

SGLang's module-based sidecar interface needs an importable entry point that composes the native SGLang engine adapter with Dynamo's unified backend lifecycle. Keeping this under dynamo.sglang makes the ownership and invocation clearer while retaining the released wheel as the only required installation.

python3 -m sglang.launch_server \
    <args> \
    --grpc-port 30001 \
    --sidecar dynamo.sglang.sidecar

Scope

This extracts the Python entry-point portion of #11636. It intentionally leaves the standalone executable changes and the lib/ directory organization to separate PRs. The Rust crate remains at lib/sglang-sidecar.

Validation

• cargo fmt --all -- --check
• cargo metadata --manifest-path lib/bindings/python/Cargo.toml --no-deps --format-version 1
• ruff check on the changed Python tests and launcher
• git diff --check

A full local Cargo test build could not complete because the workspace filesystem ran out of space while compiling Dynamo's transitive dependencies; draft PR CI will provide the full build and test result.

Summary by CodeRabbit

• New Features

  • Added a dedicated SGLang sidecar launcher that supports command-line arguments and uses the native backend runner.
  • Updated the Python interface to expose the launcher through the backend module.

• Removed

  • Removed the previous standalone SGLang sidecar entry point.

• Tests

  • Added coverage for argument forwarding, default process arguments, logging behavior, and backend interface availability.

[datadog-official]

⚠️ Warnings

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

[coderabbitai]

Walkthrough

Changes

The SGLang sidecar launcher now runs through a backend-scoped Rust binding and a new Python module. The former top-level entrypoint is removed, type stubs and tests are updated, and ownership and CI path mappings exclude the old sidecar directory.

SGLang sidecar launcher

Layer / File(s)	Summary
Backend launcher binding lib/bindings/python/rust/backend.rs, lib/bindings/python/rust/llm/entrypoint.rs, lib/bindings/python/rust/lib.rs, lib/bindings/python/src/dynamo/_core.pyi, components/src/dynamo/common/backend/tests/test_backend_bindings.py	Adds backend._run_sglang_sidecar, removes the former top-level export, updates the type stub, and verifies the backend attribute is callable.
Python sidecar entrypoint and tests components/src/dynamo/sglang/sidecar.py, components/src/dynamo/sglang/tests/test_sidecar.py	Adds logging-aware argument forwarding through dynamo.sglang.sidecar and tests explicit arguments, process arguments, and import behavior.
SGLang path routing updates .github/codeowners/areas.yaml, .github/filters.yaml, CODEOWNERS	Removes the old sglang_sidecar path from backend ownership and SGLang CI filtering mappings.

Estimated code review effort: 3 (Moderate) | ~20 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is detailed but does not follow the required template and omits the mandatory Related Issues section and reviewer-start guidance.	Add the required Overview, Details, Where should reviewer start?, and Related Issues sections, and include either the linked issue number or the no-issue confirmation.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: adding a managed Python SGLang sidecar entrypoint.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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[coderabbitai]

🧹 Nitpick comments (1)

lib/bindings/python/rust/llm/entrypoint.rs (1)

951-956: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Reuse the crate-level to_pyerr helper
lib/bindings/python/rust/llm/entrypoint.rs:951 duplicates the shared crate::to_pyerr already defined in lib/bindings/python/rust/lib.rs. Use the shared helper here instead of keeping a second conversion path.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/bindings/python/rust/llm/entrypoint.rs` around lines 951 - 956, Remove
the local to_pyerr function in entrypoint.rs and reuse the existing crate-level
crate::to_pyerr helper for all corresponding error conversions, preserving the
current PyErr behavior.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@lib/bindings/python/rust/llm/entrypoint.rs`:
- Around line 951-956: Remove the local to_pyerr function in entrypoint.rs and
reuse the existing crate-level crate::to_pyerr helper for all corresponding
error conversions, preserving the current PyErr behavior.

---

ℹ️ Review info

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Run ID: ae44fcb0-2e5f-46df-985e-3852793b4c31

📥 Commits

Reviewing files that changed from the base of the PR and between 01d2cb2 and f827205.

📒 Files selected for processing (13)

• .github/codeowners/areas.yaml
• .github/filters.yaml
• CODEOWNERS
• components/src/dynamo/common/backend/tests/test_backend_bindings.py
• components/src/dynamo/sglang/sidecar.py
• components/src/dynamo/sglang/tests/test_sidecar.py
• components/src/dynamo/sglang_sidecar/__init__.py
• components/src/dynamo/sglang_sidecar/__main__.py
• components/src/dynamo/sglang_sidecar/main.py
• lib/bindings/python/rust/backend.rs
• lib/bindings/python/rust/lib.rs
• lib/bindings/python/rust/llm/entrypoint.rs
• lib/bindings/python/src/dynamo/_core.pyi

💤 Files with no reviewable changes (7)

• components/src/dynamo/sglang_sidecar/main.py
• components/src/dynamo/sglang_sidecar/init.py
• .github/filters.yaml
• CODEOWNERS
• components/src/dynamo/sglang_sidecar/main.py
• .github/codeowners/areas.yaml
• lib/bindings/python/rust/lib.rs