vllm-project/semantic-router - Open Source PR Review Scorecard

A programmable Mixture-of-Models router for heterogeneous LLM inference

C-Rank Grade: A (Welcoming) - 68/100

External PR Merge Rate: 62%

Response Time: 16h

First Timer Success: 53%

Frequently Asked Questions

Is vllm-project/semantic-router welcoming to first-time open-source contributors?

vllm-project/semantic-router has a recorded first-timer success rate of 52.8%. Repositories ranked A typically provide actionable feedback during code reviews and actively nurture new community contributors.

How fast can I expect code review feedback on my pull request?

Maintainers in vllm-project/semantic-router respond to incoming external pull requests in approximately 16.4 hours on average. Keeping PRs focused on single tasks and ensuring tests pass helps maintainers review faster.

What does the 68.2 C-Rank™ score (A Tier) represent?

The C-Rank™ system evaluates GitHub projects on a 0–100 scale using real data: PR merge rates, review turnaround time, active maintainer presence, and first-time contributor success. A score of 68.2 places vllm-project/semantic-router in the A tier.

What is the external contributor pull request merge rate for vllm-project/semantic-router?

The external contributor pull request merge rate for vllm-project/semantic-router is 61.8%, based on public PR activity from non-core contributors.

Are there Good First Issues available in vllm-project/semantic-router?

vllm-project/semantic-router currently has 2 active issue(s) tagged with beginner-friendly labels like "good first issue", "beginner", or "up-for-grabs".

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A programmable Mixture-of-Models router for heterogeneous LLM inference

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AI Maintainer Review Guidelines

Review Persona

High-Friction Gatekeeper

Warmth Score
6.2/10
Patience Score
6.9/10
Nitpick Rate
49%

Rigorous architecture standards (75% critical review signals). Ensure PRs strictly follow guidelines before requesting review in vllm-project/semantic-router.

Top PR Submission Do's

  • •Add unit tests with >80% coverage for modified code paths
  • •Run repository linter and code formatters locally before pushing
  • •Link relevant GitHub issue ID in PR description pre-flight checklist

Top PR Friction Pitfalls (Don'ts)

  • •Do not submit unlinked PRs without referencing an existing issue
  • •Do not mix refactoring and feature logic into a single commit
  • •Do not ping maintainers repeatedly within 24 hours of opening
Response Velocity
16 hours
Standard maintainer review cycle

Average Response Latency

Tracks hours until a maintainer leaves a review, comment, or PR response.

Merge Efficiency
61.8%
Moderate PR acceptance rate

External Acceptance Rate

Percentage of community pull requests successfully merged into main.

First-Timer Success
52.8%
Strong first-timer PR acceptance rate

First PR Conversion

Rate at which developers submitting their first repository PR succeed.

Active Maintainers
131 core
Highly collaborative maintainer core
Diagnostic Health HUD
61.8%
Merge Gauge
52.8%
1st-Timer
Community Vibe58/100

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Active Good First Issues (5)

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Problem The model runtime's cuda accelerator is implemented and unit-tested, but not validated on NVIDIA GPUs. Its fused kernels stay disabled until a bit-exactness record exists, and the user guide lists NVIDIA GPUs as "work but not yet validated". Scope On NVIDIA GPUs (for example H100, A100 or L4): A GPU smoke of the CUDA router image as the charts run it. Golden answers for every built-in model the CUDA image serves on the GPU. Parity records per family against the released references: Decision 1.0 and Decision 2.0 panels, Vela 2.0's request panel, and the Vela 1.0 path. A bit-exactness record for each fused kernel slot before it is enabled on CUDA, plus pinned FLA kernel choices for the Qwen3.5 decoders. Performance records against the legacy path or the released runtime, to the repository's no-regression standard. The user guide and design doc updated from "unvalidated" to "validated" for what was measured. Acceptance All records committed under src/model-runtime/docs/records/,

📅 Opened Oct 6, 2026💬 3 comments
Quality: 90/100Contribute

Goal Make it clear what each router checkpoint was trained on. Eight Vela cards (Domain, Guard, PII, Safety, Hazard, FactCheck, Feedback, Modality) don't name their training data, either in the datasets metadata or in the text, and Halu lists its two LettuceDetect datasets only in the metadata. The Vela Shield card already does this: every source with licence, revision and rows used, and an exposure column in each eval table saying which compared model trained on the same source. It matters when choosing eval sets. The older intent classifier names MMLU-Pro as its training data and scores 0.944 on the 12,032-question MMLU-Pro test split, against 0.496 on 1,988 MMLU-CF questions and 0.606 on 1,882 SuperGPQA questions mapped to the same labels. Vela Domain scores 0.709, 0.529 and 0.587. With the older card a reader can see why its first number is high. The Vela card names nothing, and its MMLU-Pro number is partly on its own training data too (#4300). Proposed Workgroup Router Models & I

📅 Opened Sep 28, 2026💬 7 comments
Quality: 90/100Contribute

Goal Part of #4241. SR Bench 2.0 should show how task success and continuity hold up when a provider fails partway through a task. Today the provider mocker's behavior is set once per process through environment variables, including one global response delay (settings.py). bench/openai_fault_proxy.py, from #1989, injects faults for the soak harness that @drivebyer built in #3264 and @xuuuge extended to streaming in #3447. Its faults also apply to the whole process. Neither lets one benchmark task ask for "return 503 on this task's third call" while other tasks run normally. @ZireaelK's #3428 adds stall probes to the mocker for timeout tests, which a schedule could reuse. This builds on that work, so @drivebyer, @xuuuge or @ZireaelK get first pick. Proposed Workgroup Evaluation & Quality Scope Let the provider mocker read a fault schedule keyed by a request-scoped value, where each entry picks a call index and a fault: an HTTP status, a delay, or a stream cut short. Let an sr-bench man

📅 Opened Sep 26, 2026💬 3 comments
Quality: 90/100Contribute

Proposed Workgroup Developer Experience & Ecosystem Describe the enhancement While checking whether a model is live on Build → Config → Models (/config/models), the Live verification control causes neighboring table columns to shift. The Pricing column’s $ symbol appears appear and disappear or slide horizontally during the Checking state, even though pricing data does not change. Screen recording: Screen.Recording.2026-09-11.at.4.50.28.PM.mov What happens Clicking Check runs a real inference probe (POST /api/models/verify). The control (ConfigPageModelLiveVerification) lives in the Live column, immediately before Pricing in ConfigPageModelInventoryPanel.tsx. Phase Status label Button label Extra UI idle Not checked Check — pending Checking Checking… yellow pulsing dot verified Live Check again green dot failed Unavailable Check again inline error message Each phase changes the width of the Live cell: Variable button label

📅 Opened Sep 11, 2026💬 4 comments
Quality: 100/100Contribute

Goal Remote classifier backends (http_classify and other connector-backed classifier calls) should stop issuing live RPCs for a bounded cooldown after consecutive timeouts or unavailability, instead of waiting on a dead endpoint on every request. The breaker only decides whether to place the call. A skipped call must still surface as the existing unresolved/timeout error so decision-tree Unknown, rules.on_unknown, and prompt-guard on_error keep their current meaning. This is the cooldown follow-up called out on #3106 and in #2759, not a replacement for those policies. Proposed Workgroup Router Models & Inference Runtime Scope Per remote-classifier backend instance in a process: consecutive-failure threshold, open interval, and a single half-open probe. On open, skip the RPC and return the same typed timeout/unavailable error the connector already returns. Default off, or on only for remote HTTP/MCP-style backends. In-process local models (mmbert / Candle) stay unchanged. Jailbreak/PII

📅 Opened Sep 11, 2026💬 3 comments
Quality: 90/100Contribute
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Contributor Compatibility & Review Speed Analysis for vllm-project/semantic-router

When evaluating whether to contribute to vllm-project/semantic-router, response velocity and maintainer engagement are crucial. GetMerged continuously tracks pull request trajectories, first-comment latency, and code review rounds to help developers avoid submitting pull requests to backlogged repositories.

Currently, maintainers of vllm-project/semantic-router acknowledge new external contributions in approximately 16 hours. Out of all submitted pull requests from non-core authors in the last 180-day window, 61.8% were successfully merged into the primary branch.

Frequently Asked Questions - Contributing to vllm-project/semantic-router

01

Is vllm-project/semantic-router welcoming to first-time open-source contributors?

vllm-project/semantic-router has a recorded first-timer success rate of 52.8%. Repositories ranked Welcoming typically provide actionable feedback during code reviews and actively nurture new community contributors.

02

How fast can I expect code review feedback on my pull request?

The initial maintainer response time averages ~16 hours. Keeping PRs scoped to single concerns and ensuring CI checks succeed will optimize review turnaround.

03

What does the 68.2 C-Rank™ score represent?

The C-Rank™ index scores repositories on a 0 to 100 scale using an objective formula: external PR merge rates, initial response speed, active maintainer count, and first-time contributor retention. A score of 68.2 places vllm-project/semantic-router in the Welcoming tier.

04

What is the external contributor pull request merge rate for vllm-project/semantic-router?

The external pull request merge rate is 61.8%. GetMerged isolates non-core community contributions so external developers get an accurate benchmark of PR acceptance probability.

05

Are there beginner Good First Issues open in vllm-project/semantic-router?

Yes, vllm-project/semantic-router currently has 2 active issue(s) tagged with beginner-friendly labels. You can inspect these directly from the repository issues tab.

GetMerged C-Rank™ Indexing Standard

All metrics displayed for vllm-project/semantic-router are automatically retrieved via the public GitHub API and recalculated daily. Insider pull requests submitted by repository owners or organization members are excluded from merge rate calculations to preserve objective external contributor statistics.