diff --git a/packages/prime-rl-configs/src/prime_rl/configs/trainer.py b/packages/prime-rl-configs/src/prime_rl/configs/trainer.py
index f4d37cd9d0..8464331bc0 100644
--- a/packages/prime-rl-configs/src/prime_rl/configs/trainer.py
+++ b/packages/prime-rl-configs/src/prime_rl/configs/trainer.py
@@ -479,8 +479,16 @@ class NCCLWeightBroadcastConfig(BaseWeightBroadcastConfig):
 ]
 
 
+class TokenExportConfig(BaseConfig):
+    """Configures per-token rollout exports from the RL trainer."""
+
+    path: Path | None = None
+    """JSONL output file. If unset, writes to ``<output_dir>/token_exports/rank_<rank>.jsonl``. Relative paths are resolved under output_dir."""
+
+
 class TrainerExperimentalConfig(BaseConfig):
-    pass
+    token_export: TokenExportConfig | None = None
+    """Opt-in per-token JSONL export for rollout debugging. When enabled, writes token ids and aligned trainer metrics after each forward pass."""
 
 
 class TrainerConfig(BaseConfig):
diff --git a/skills/configs/SKILL.md b/skills/configs/SKILL.md
index 1eddac38ac..c8ca0fe463 100644
--- a/skills/configs/SKILL.md
+++ b/skills/configs/SKILL.md
@@ -60,6 +60,18 @@ CLI: `--env.0.id reverse-text --env.1.id math-env`.
 
 In TOML, an empty section header (`[ckpt]`) does the same.
 
+## RL trainer token exports
+
+For rollout debugging, enable trainer-side token export under `trainer.experimental.token_export` (or `experimental.token_export` when running the trainer entrypoint directly). It writes one JSONL record per exported sequence. Each record stores aligned per-token arrays for token ids, loss mask, advantage, reward, entropy, mismatch KL, inference/trainer logprobs, importance ratios, probability deltas, and masking diagnostics. It does not decode token text in the trainer.
+
+```toml
+[trainer.experimental.token_export]
+# Optional. Relative paths resolve under trainer.output_dir.
+path = "token_exports/sample.jsonl"
+```
+
+Leave it unset for normal training. When enabled, it exports every sequence from each exporting rank.
+
 ## Key files
 
 - `packages/prime-rl-configs/src/prime_rl/` — config classes under `configs/`; `utils/config.py` re-exports `BaseConfig` and `cli`
diff --git a/src/prime_rl/trainer/batch.py b/src/prime_rl/trainer/batch.py
index 9f0a923b89..9db4aefd74 100644
--- a/src/prime_rl/trainer/batch.py
+++ b/src/prime_rl/trainer/batch.py
@@ -12,6 +12,8 @@ def prepare_sample(training_example: TrainingSample, seq_len: int) -> MicroBatch
     loss_mask = training_example.prompt_mask + training_example.completion_mask
     inference_logprobs = [0.0] * len(training_example.prompt_ids) + training_example.completion_logprobs
     advantages = [training_example.advantage] * len(input_ids)
+    reward = training_example.reward if training_example.reward is not None else float("nan")
+    rewards = [reward] * len(input_ids)
     position_ids = list(range(len(input_ids)))
     mm_token_type_ids = training_example.mm_token_type_ids
     assert training_example.env_name != "all", "env_name='all' is reserved for aggregate metric keys"
@@ -33,6 +35,7 @@ def prepare_sample(training_example: TrainingSample, seq_len: int) -> MicroBatch
         inference_logprobs = inference_logprobs[:seq_len]
         position_ids = position_ids[:seq_len]
         advantages = advantages[:seq_len]
+        rewards = rewards[:seq_len]
         temperatures = temperatures[:seq_len]
         if teacher_logprobs is not None:
             teacher_logprobs = teacher_logprobs[:seq_len]
@@ -48,9 +51,10 @@ def prepare_sample(training_example: TrainingSample, seq_len: int) -> MicroBatch
         == len(loss_mask)
         == len(position_ids)
         == len(inference_logprobs)
+        == len(rewards)
         == len(temperatures)
     ), (
-        f"input_ids: {len(input_ids)}, advantages: {len(advantages)}, loss_mask: {len(loss_mask)}, position_ids: {len(position_ids)}, inference_logprobs: {len(inference_logprobs)}, temperatures: {len(temperatures)}"
+        f"input_ids: {len(input_ids)}, advantages: {len(advantages)}, loss_mask: {len(loss_mask)}, position_ids: {len(position_ids)}, inference_logprobs: {len(inference_logprobs)}, rewards: {len(rewards)}, temperatures: {len(temperatures)}"
     )
     if teacher_logprobs is not None:
         assert len(teacher_logprobs) == len(input_ids), f"teacher_logprobs: {len(teacher_logprobs)}"
@@ -74,6 +78,7 @@ def prepare_sample(training_example: TrainingSample, seq_len: int) -> MicroBatch
         inference_logprobs=inference_logprobs,
         teacher_logprobs=teacher_logprobs,
         temperatures=temperatures,
+        rewards=rewards,
         routed_experts=routed_experts,
         mm_token_type_ids=mm_token_type_ids,
         env_names=env_names,
@@ -122,9 +127,16 @@ def packed_samples_into_micro_bs(
                 len(bin_content.input_ids) + len(sample.input_ids) <= max_seq_len
                 and bin_content.training_mode == sample.training_mode
             ):
+                existing_len = len(bin_content.input_ids)
                 bin_content.input_ids.extend(sample.input_ids)
                 bin_content.loss_mask.extend(sample.loss_mask)
                 bin_content.advantages.extend(sample.advantages)
+                if sample.rewards is not None:
+                    if bin_content.rewards is None:
+                        bin_content.rewards = [float("nan")] * existing_len
+                    bin_content.rewards.extend(sample.rewards)
+                elif bin_content.rewards is not None:
+                    bin_content.rewards.extend([float("nan")] * len(sample.input_ids))
                 bin_content.inference_logprobs.extend(sample.inference_logprobs)
                 bin_content.temperatures.extend(sample.temperatures)
                 if sample.teacher_logprobs is not None:
@@ -175,6 +187,8 @@ def pad_micro_batch(micro_batch: MicroBatch, pad_to_multiple_of: int) -> MicroBa
 
     micro_batch.input_ids.extend([1] * padding_size)
     micro_batch.advantages.extend([0.0] * padding_size)
+    if micro_batch.rewards is not None:
+        micro_batch.rewards.extend([float("nan")] * padding_size)
     micro_batch.loss_mask.extend([False] * padding_size)
     micro_batch.position_ids.extend(list(range(padding_size)))
     micro_batch.inference_logprobs.extend([0.0] * padding_size)
diff --git a/src/prime_rl/trainer/rl/data.py b/src/prime_rl/trainer/rl/data.py
index acc6b23384..73e35159af 100644
--- a/src/prime_rl/trainer/rl/data.py
+++ b/src/prime_rl/trainer/rl/data.py
@@ -20,6 +20,7 @@ class TensorMicroBatch(TypedDict):
     input_ids: Int[Tensor, "batch seq"]
     position_ids: Int[Tensor, "batch seq"]
     advantages: Float[Tensor, "batch seq"]
+    rewards: Float[Tensor, "batch seq"] | None
     inference_logprobs: Float[Tensor, "batch seq"]
     teacher_logprobs: Float[Tensor, "batch seq"] | None
     loss_mask: Bool[Tensor, "batch seq"]
@@ -108,6 +109,7 @@ def _get_sample_micro_batch(self, generator: torch.Generator) -> TensorMicroBatc
             "input_ids": input_ids.unsqueeze(0),
             "position_ids": position_ids.unsqueeze(0),
             "advantages": advantages.unsqueeze(0),
+            "rewards": None,
             "inference_logprobs": inference_logprobs.unsqueeze(0),
             "teacher_logprobs": None,
             "temperatures": torch.ones(input_ids.shape[0]).unsqueeze(0),
@@ -135,6 +137,7 @@ def _get_micro_batch(self, generator: torch.Generator) -> TensorMicroBatch:
             ),
             "position_ids": torch.cat([torch.arange(self.seq_len)]).unsqueeze(0),
             "advantages": torch.randn(self.seq_len, generator=generator).unsqueeze(0),
+            "rewards": None,
             "inference_logprobs": torch.randn(self.seq_len, generator=generator).unsqueeze(0),
             "teacher_logprobs": None,
             "temperatures": torch.ones(self.seq_len).unsqueeze(0),
@@ -211,6 +214,9 @@ def _micro_batch_to_tensor(self, micro_batch: MicroBatch) -> TensorMicroBatch:
             input_ids=torch.tensor(micro_batch.input_ids, dtype=torch.long).unsqueeze(0),
             position_ids=torch.tensor(micro_batch.position_ids, dtype=torch.long).unsqueeze(0),
             advantages=torch.tensor(micro_batch.advantages, dtype=torch.float).unsqueeze(0),
+            rewards=torch.tensor(micro_batch.rewards, dtype=torch.float).unsqueeze(0)
+            if micro_batch.rewards is not None
+            else None,
             inference_logprobs=torch.tensor(micro_batch.inference_logprobs, dtype=torch.float).unsqueeze(0),
             teacher_logprobs=torch.tensor(micro_batch.teacher_logprobs, dtype=torch.float).unsqueeze(0)
             if micro_batch.teacher_logprobs is not None
diff --git a/src/prime_rl/trainer/rl/token_export.py b/src/prime_rl/trainer/rl/token_export.py
new file mode 100644
index 0000000000..a142088b82
--- /dev/null
+++ b/src/prime_rl/trainer/rl/token_export.py
@@ -0,0 +1,234 @@
+import atexit
+import json
+import math
+from collections.abc import Mapping, Sequence
+from pathlib import Path
+from typing import Any
+
+import torch
+from torch import Tensor
+
+from prime_rl.configs.trainer import DefaultLossConfig, TokenExportConfig, TrainerConfig
+from prime_rl.trainer.rl.loss import compute_importance_ratio_and_mismatch_kl
+
+SCHEMA_VERSION = 1
+
+
+class DisabledTokenExporter:
+    def export(self, *args: Any, **kwargs: Any) -> None:
+        return
+
+    def close(self) -> None:
+        return
+
+
+class TokenExporter:
+    def __init__(
+        self,
+        config: TokenExportConfig,
+        output_dir: Path,
+        rank: int,
+    ) -> None:
+        self.config = config
+        self.rank = rank
+        self.path = self._resolve_path(config.path, output_dir, rank)
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        self._file = self.path.open("a", encoding="utf-8")
+        self._closed = False
+        self._current_step: int | None = None
+        self._sequences_this_step = 0
+        atexit.register(self.close)
+
+    def export(
+        self,
+        step: int,
+        micro_step: int,
+        micro_batch: Mapping[str, Any],
+        model_output: Mapping[str, Tensor],
+        response_lengths: list[int],
+        loss_config: Any,
+    ) -> None:
+        if self._current_step != step:
+            self._current_step = step
+            self._sequences_this_step = 0
+
+        columns = _export_columns(micro_batch, model_output, loss_config)
+        _check_lengths(columns)
+
+        start = 0
+        for micro_sequence_idx, length in enumerate(response_lengths):
+            raw_end = start + length
+            end = _trim_padding(columns, start, raw_end)
+            if end > start and any(columns["loss_mask"][start:end]):
+                self._write(
+                    {
+                        "schema_version": SCHEMA_VERSION,
+                        "step": step,
+                        "rank": self.rank,
+                        "micro_step": micro_step,
+                        "micro_sequence_idx": micro_sequence_idx,
+                        "export_sequence_idx": self._sequences_this_step,
+                        "env_name": _first_non_empty(columns["env_names"][start:end]),
+                        "training_mode": str(micro_batch["training_mode"]),
+                        **_slice_columns(columns, start, end),
+                    }
+                )
+                self._sequences_this_step += 1
+            start = raw_end
+
+    def close(self) -> None:
+        if self._closed:
+            return
+        self._closed = True
+        self._file.close()
+
+    def _write(self, record: dict[str, Any]) -> None:
+        if self._closed:
+            raise RuntimeError(f"Token exporter is closed for {self.path}")
+        self._file.write(json.dumps(record, separators=(",", ":"), allow_nan=False) + "\n")
+
+    @staticmethod
+    def _resolve_path(path: Path | None, output_dir: Path, rank: int) -> Path:
+        if path is None:
+            return output_dir / "token_exports" / f"rank_{rank}.jsonl"
+        if path.is_absolute():
+            return path
+        return output_dir / path
+
+
+def setup_token_exporter(
+    config: TrainerConfig, parallel_dims: Any, world: Any, logger: Any
+) -> TokenExporter | DisabledTokenExporter:
+    token_export_config = config.experimental.token_export
+    if token_export_config is None:
+        return DisabledTokenExporter()
+    if parallel_dims.cp_enabled and parallel_dims.world_mesh["cp"].get_local_rank() != 0:
+        return DisabledTokenExporter()
+
+    exporter = TokenExporter(token_export_config, config.output_dir, world.rank)
+    logger.info(f"Writing token exports to {exporter.path}")
+    return exporter
+
+
+def _export_columns(
+    micro_batch: Mapping[str, Any], model_output: Mapping[str, Tensor], loss_config: Any
+) -> dict[str, list[Any]]:
+    token_ids = _tensor_to_ints(micro_batch["input_ids"])
+    seq_len = len(token_ids)
+    trainer_logprobs = model_output["logprobs"]
+    export_tensors = _compute_export_tensors(micro_batch, trainer_logprobs, loss_config)
+
+    return {
+        "token_ids": token_ids,
+        "position_ids": _tensor_to_ints(micro_batch["position_ids"]),
+        "loss_mask": _tensor_to_bools(micro_batch["loss_mask"]),
+        "advantages": _tensor_to_floats(micro_batch["advantages"]),
+        "rewards": _optional_tensor_to_floats(micro_batch.get("rewards"), seq_len),
+        "inference_logprobs": _tensor_to_floats(micro_batch["inference_logprobs"]),
+        "trainer_logprobs": _tensor_to_floats(trainer_logprobs),
+        "entropy": _tensor_to_floats(model_output["entropy"]),
+        "mismatch_kl": _optional_tensor_to_floats(export_tensors["mismatch_kl"], seq_len),
+        "log_importance_ratio": _optional_tensor_to_floats(export_tensors["log_importance_ratio"], seq_len),
+        "importance_ratio": _optional_tensor_to_floats(export_tensors["importance_ratio"], seq_len),
+        "prob_delta": _optional_tensor_to_floats(export_tensors["prob_delta"], seq_len),
+        "is_masked": _optional_tensor_to_bools(export_tensors["is_masked"], seq_len),
+        "is_masked_high": _optional_tensor_to_bools(export_tensors["is_masked_high"], seq_len),
+        "is_masked_low": _optional_tensor_to_bools(export_tensors["is_masked_low"], seq_len),
+        "env_names": list(micro_batch["env_names"]),
+    }
+
+
+def _compute_export_tensors(
+    micro_batch: Mapping[str, Any], trainer_logprobs: Tensor, loss_config: Any
+) -> dict[str, Tensor | None]:
+    fields: dict[str, Tensor | None] = {
+        "log_importance_ratio": None,
+        "importance_ratio": None,
+        "mismatch_kl": None,
+        "prob_delta": None,
+        "is_masked": None,
+        "is_masked_high": None,
+        "is_masked_low": None,
+    }
+    if micro_batch["training_mode"] == "sft":
+        return fields
+
+    inference_logprobs = micro_batch["inference_logprobs"].to(trainer_logprobs.device)
+    loss_mask = micro_batch["loss_mask"].to(trainer_logprobs.device)
+    advantages = micro_batch["advantages"].to(trainer_logprobs.device)
+    with torch.no_grad():
+        log_ratio, ratio, mismatch_kl = compute_importance_ratio_and_mismatch_kl(trainer_logprobs, inference_logprobs)
+        prob_delta = torch.exp(trainer_logprobs) - torch.exp(inference_logprobs)
+        fields["log_importance_ratio"] = log_ratio
+        fields["importance_ratio"] = ratio
+        fields["mismatch_kl"] = mismatch_kl
+        fields["prob_delta"] = prob_delta
+        if isinstance(loss_config, DefaultLossConfig):
+            invalid_high = prob_delta > loss_config.dppo_mask_high
+            invalid_low = prob_delta < -loss_config.dppo_mask_low
+            positive_advantages = advantages > 0
+            negative_advantages = advantages < 0
+            invalid = torch.where(positive_advantages, invalid_high, invalid_low)
+            fields["is_masked"] = loss_mask & invalid
+            fields["is_masked_high"] = loss_mask & positive_advantages & invalid_high
+            fields["is_masked_low"] = loss_mask & negative_advantages & invalid_low
+    return fields
+
+
+def _tensor_to_ints(tensor: Tensor) -> list[int]:
+    return [int(value) for value in tensor.detach().cpu().reshape(-1).tolist()]
+
+
+def _tensor_to_bools(tensor: Tensor) -> list[bool]:
+    return [bool(value) for value in tensor.detach().cpu().reshape(-1).tolist()]
+
+
+def _tensor_to_floats(tensor: Tensor) -> list[float | None]:
+    values = tensor.detach().to(dtype=torch.float32, device="cpu").reshape(-1).tolist()
+    return [_json_float(value) for value in values]
+
+
+def _optional_tensor_to_floats(tensor: Tensor | None, seq_len: int) -> list[float | None]:
+    if tensor is None:
+        return [None] * seq_len
+    return _tensor_to_floats(tensor)
+
+
+def _optional_tensor_to_bools(tensor: Tensor | None, seq_len: int) -> list[bool | None]:
+    if tensor is None:
+        return [None] * seq_len
+    return _tensor_to_bools(tensor)
+
+
+def _check_lengths(columns: Mapping[str, Sequence[Any]]) -> None:
+    lengths = {key: len(values) for key, values in columns.items()}
+    if len(set(lengths.values())) != 1:
+        raise ValueError(f"Token export fields must have aligned lengths, got {lengths}")
+
+
+def _slice_columns(columns: Mapping[str, Sequence[Any]], start: int, end: int) -> dict[str, list[Any]]:
+    return {key: list(values[start:end]) for key, values in columns.items() if key != "env_names"}
+
+
+def _trim_padding(columns: Mapping[str, Sequence[Any]], start: int, end: int) -> int:
+    env_names = columns["env_names"]
+    loss_mask = columns["loss_mask"]
+    while end > start and env_names[end - 1] == "" and not loss_mask[end - 1]:
+        end -= 1
+    return end
+
+
+def _json_float(value: float | None) -> float | None:
+    if value is None:
+        return None
+    value = float(value)
+    if not math.isfinite(value):
+        return None
+    return value
+
+
+def _first_non_empty(values: Sequence[str]) -> str | None:
+    for value in values:
+        if value:
+            return value
+    return None
diff --git a/src/prime_rl/trainer/rl/train.py b/src/prime_rl/trainer/rl/train.py
index e437efb9e2..d359bae5e7 100644
--- a/src/prime_rl/trainer/rl/train.py
+++ b/src/prime_rl/trainer/rl/train.py
@@ -35,6 +35,7 @@
     shift_tensor_left,
     shift_tensor_right,
 )
+from prime_rl.trainer.rl.token_export import setup_token_exporter
 from prime_rl.trainer.model import (
     forward,
     setup_tokenizer,
@@ -239,6 +240,8 @@ def load_run_checkpoint(_optimizer, idx: int) -> None:
             config.rollout_transport,
         )
 
+    token_exporter = setup_token_exporter(config, parallel_dims, world, logger)
+
     gc_handler = GarbageCollection(config.gc.interval) if config.gc else None
 
     logger.info(f"Starting training loop (max_steps={config.max_steps or 'infinite'})")
@@ -500,6 +503,8 @@ def load_run_checkpoint(_optimizer, idx: int) -> None:
                 for env_name, indices in env_to_indices.items():
                     tensors[f"mismatch_kl/{env_name}"].append(mismatch_kl[indices])
 
+            token_exporter.export(progress.step, micro_step, micro_batch, out, response_lengths, config.loss)
+
             if is_tt_moe_model(model):
                 load_balance_stats = get_load_balance_stats(model)
                 for k, v in load_balance_stats.items():
@@ -678,6 +683,8 @@ def load_run_checkpoint(_optimizer, idx: int) -> None:
         prof.export_chrome_trace(trace_file)
         logger.info(f"Saved trace to {trace_file}")
 
+    token_exporter.close()
+
     # Write final checkpoint (only for single-run mode; multi-run checkpoints are managed by MultiCheckpointManager)
     if config.max_concurrent_runs == 1 and ckpt_manager is not None:
         if not (config.ckpt and config.ckpt.weights_only):
diff --git a/src/prime_rl/transport/types.py b/src/prime_rl/transport/types.py
index de9b246eb2..d4c947224f 100644
--- a/src/prime_rl/transport/types.py
+++ b/src/prime_rl/transport/types.py
@@ -80,3 +80,4 @@ class MicroBatch(msgspec.Struct, array_like=True, gc=False, omit_defaults=True):
     # Loss dispatch is batch-driven (rl/opd → default loss with mode-specific taus,
     # sft → sft loss). All samples packed into a micro batch share the same mode.
     training_mode: TrainingMode = "rl"
+    rewards: list[float] | None = None