Overview:

Adds NVIDIA Dynamo as an optional inference backend alongside the existing vLLM path. Controlled by a new ClientConfig.backend field ("vllm" | "dynamo"). Three self-contained changes: a pluggable AdminAPI abstraction, renderer_transport selection for the verifiers wire shape, and a Dynamo teacher-logprobs path for OPD training.

Details:

packages/prime-rl-configs/src/prime_rl/configs/shared.py

• ClientConfig.backend: Literal["vllm", "dynamo"] — selects the AdminAPI implementation and verifiers wire shape. Default "vllm" is a no-op for existing configs.
• ClientConfig.rl_base_url — optional override for the Dynamo RL worker discovery listener (GET /v1/rl/workers). When unset, the port is derived from DYN_RL_PORT (default 8001).

src/prime_rl/utils/client.py

• AdminAPI Protocol + VLLMAdminAPI — extracts the existing vLLM admin paths (/pause, /resume, /update_weights, /load_lora_adapter, /init_broadcaster) into a typed protocol. VLLMAdminAPI methods go through a shared _admin_post helper that adds bounded per-attempt timeouts and tenacity retry on 5xx/transport errors (300 s for pause/resume, 720 s for weight updates).
• DynamoAdminAPI — Dynamo worker admin over POST /engine/<method>: pause_generation, resume_generation, update_weights_from_disk / update_weights_from_distributed (filesystem vs NCCL paths), load_lora_adapter. Inherits health/model checks from VLLMAdminAPI.
• setup_admin_api(client_config) — picks DynamoAdminAPI when backend="dynamo", VLLMAdminAPI otherwise.
• discover_dynamo_admin_base_urls — resolves worker system URLs from GET /v1/rl/workers; falls back to port-replaced base_url when rl_base_url is unset.
• setup_clients — sets renderer_transport="dynamo_chat" on all vf.ClientConfig objects when backend="dynamo", "vllm_generate" otherwise. Requires verifiers #1574 + renderers #79.

src/prime_rl/orchestrator/utils.py

• Splits compute_teacher_logprobs into two paths dispatched on client_config.renderer_transport: _compute_teacher_logprobs_vllm (existing /inference/v1/generate path) and _compute_teacher_logprobs_dynamo (POST /v1/chat/completions with nvext.token_data + nvext.extra_fields=["prompt_logprobs"]).
• _flatten_prompt_logprobs — shared flattener that handles both vLLM typed Logprob objects and Dynamos dict shape {logprob, rank?, decoded_token?}.

Where should the reviewer start?

1. src/prime_rl/utils/client.py — AdminAPI protocol (line ~32), DynamoAdminAPI class, setup_admin_api, and setup_clients renderer_transport selection. Core of the change.
2. src/prime_rl/orchestrator/utils.py — _compute_teacher_logprobs_dynamo and the compute_teacher_logprobs dispatcher. Note the placeholder messages field required by the Dynamo frontend even when nvext.token_data is set.
3. packages/prime-rl-configs/src/prime_rl/configs/shared.py — the two new ClientConfig fields; verify defaults are backward-compatible.

Related Issues:

• Relates to verifiers #1574 — adds renderer_transport field to vf.ClientConfig
• Relates to renderers #79 — adds dynamo_chat transport to renderers.generate()