Runtime plane / Tier 1 / Phase 1
Model & Inference
Which intelligence executes?
Serve, version and scale the models — proprietary and open-weight — with predictable latency and cost, and keep them swappable so no single provider becomes load-bearing.
01 / WHAT THIS BOUNDARY OWNS
- Inference serving: batching, KV cache, tensor and pipeline parallelism
- Model registry and version pinning, including deprecation calendars
- Routing between model tiers, plus fallbacks when a provider degrades
- Embedding and reranking endpoints used by retrieval
- Capacity and quota per tenant on shared accelerators
02 / INTEGRATION POINTS
01
Infrastructure & Runtime
03runs on scheduled GPU capacity
AI Gateway
07exposed only through the gateway
Retrieval & Context Engineering
15consumes assembled context under a token budget
Observability & FinOps
16emits token and latency telemetry
Evaluation & Assurance
model changes gated by regression evaluation
03 / ENTERPRISE ACCOUNTABILITY
ML Platform / AI Engineering
- Head of ML Platform — accountable owner
- Inference engineer — serving performance and memory
- GPU performance engineer — batching, quantisation, cache
- Model operations engineer — versions, rollouts, deprecations
Architectural recommendation, not a research finding.
04 / WHAT DONE LOOKS LIKE
Pilot needs one hosted model and one self-hosted fallback behind the same interface, both version-pinned, with a documented switch procedure.
Signals to watch
- Time to first token and tokens per second
- P99 end-to-end latency by model tier
- Prefix cache hit rate
- Cost per thousand tokens by tenant
- Share of traffic that could fail over to the open-weight path
05 / FAILURE MODES
- Vendor lock-in through provider-specific features in prompts and tools
- Silent provider upgrades shifting behaviour mid-quarter
- KV cache reuse leaking context across tenants if isolation is careless
- P99 latency collapsing under burst without admission control
06 / REFERENCE LANDSCAPE
Tool and standards snapshot · last reviewed approximately mid-2026
Open source
- vLLM
- llm-d
- SGLang
- TensorRT-LLM
- KServe or Ray Serve
- Hugging Face TGI
- Text Embeddings Inference
Managed
- Anthropic API
- Bedrock, Vertex AI, Azure AI Foundry
- Managed embedding and rerank endpoints
Standards
- OpenAI-compatible API surface
- JSON Schema structured outputs
- Model cards for each served version
ARCHITECTURE NOTE
Keeping this harness distinct from Infrastructure is what makes model choice reversible. If serving is buried in the platform, changing models becomes a platform migration.
