From 755c56d06e8a4933f4d77734485b336987b52483 Mon Sep 17 00:00:00 2001 From: guozhihao-224 Date: Sat, 18 Apr 2026 11:25:09 +0800 Subject: [PATCH] docs: clarify backend field is required, no implicit inheritance The `backend` field in `TrainEngineConfig` has `default=MISSING`, making it required. The docs previously claimed that empty `critic.backend` or `ref.backend` would "automatically inherit" from `actor.backend`, but there is no code-level fallback. Clarify that users should use OmegaConf interpolation (`${actor.backend}`) to share the actor backend. Ref: #1165 (Finding #1) Co-Authored-By: Claude Opus 4.6 --- docs/en/reference/alloc_mode.md | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/docs/en/reference/alloc_mode.md b/docs/en/reference/alloc_mode.md index 9188bee781..b23760017d 100644 --- a/docs/en/reference/alloc_mode.md +++ b/docs/en/reference/alloc_mode.md @@ -30,17 +30,18 @@ rollout: actor: backend: "fsdp:d8" -# Critic engine (falls back to actor.backend if empty) +# Critic engine (use YAML interpolation to share actor's backend) critic: - backend: "" + backend: "${actor.backend}" -# Ref engine (falls back to actor.backend if empty) +# Ref engine (use YAML interpolation to share actor's backend) ref: - backend: "" + backend: "${actor.backend}" ``` -When `critic.backend` or `ref.backend` is empty, it automatically inherits from -`actor.backend`. +The `backend` field is required for all engines. To reuse the actor's backend +configuration, use OmegaConf interpolation `${actor.backend}` as shown above. +There is no implicit fallback—an empty or missing `backend` value will raise an error. > **Note:** The top-level `allocation_mode` config field is deprecated and only retained > for backward compatibility with legacy SPMD launchers (local/ray/slurm). It is ignored