allow for image pretraining on video tokenizer

Update Discord channel link in README to use permanent link

.github/workflows/test.yml

@@ -5,11 +5,11 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-    timeout-minutes: 20
+    timeout-minutes: 60
     strategy:
       fail-fast: false
       matrix:
-        group: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+        group: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
 
     steps:
     - uses: actions/checkout@v4
@@ -24,4 +24,4 @@ jobs:
         python -m uv pip install -e .[test]
     - name: Test with pytest
       run: |
-        python -m pytest --num-shards 10 --shard-id ${{ matrix.group }} tests/
+        python -m pytest --num-shards 20 --shard-id ${{ matrix.group }} tests/

README.md

@@ -1,10 +1,99 @@
 <img src="./dreamer4-fig2.png" width="400px"></img>
 
-## Dreamer 4 (wip)
+## Dreamer 4
 
 Implementation of Danijar's [latest iteration](https://arxiv.org/abs/2509.24527v1) for his [Dreamer](https://danijar.com/project/dreamer4/) line of work
 
-[Temporary Discord](https://discord.gg/MkACrrkrYR)
+[Discord channel](https://discord.gg/PmGR7KRwxq) for collaborating with other researchers interested in this work
+
+## Appreciation
+
+- [@dirkmcpherson](https://github.com/dirkmcpherson) for fixes to typo errors and unpassed arguments!
+
+## Install
+
+```bash
+$ pip install dreamer4
+```
+
+## Usage
+
+```python
+import torch
+from dreamer4 import VideoTokenizer, DynamicsWorldModel
+
+# video tokenizer, learned through MAE + lpips
+
+tokenizer = VideoTokenizer(
+    dim = 512,
+    dim_latent = 32,
+    patch_size = 32,
+    image_height = 256,
+    image_width = 256
+)
+
+video = torch.randn(2, 3, 10, 256, 256)
+
+# learn the tokenizer
+
+loss = tokenizer(video)
+loss.backward()
+
+# dynamics world model
+
+world_model = DynamicsWorldModel(
+    dim = 512,
+    dim_latent = 32,
+    video_tokenizer = tokenizer,
+    num_discrete_actions = 4,
+    num_residual_streams = 1
+)
+
+# state, action, rewards
+
+video = torch.randn(2, 3, 10, 256, 256)
+discrete_actions = torch.randint(0, 4, (2, 10, 1))
+rewards = torch.randn(2, 10)
+
+# learn dynamics / behavior cloned model
+
+loss = world_model(
+    video = video,
+    rewards = rewards,
+    discrete_actions = discrete_actions
+)
+
+loss.backward()
+
+# do the above with much data
+
+# then generate dreams
+
+dreams = world_model.generate(
+    10,
+    batch_size = 2,
+    return_decoded_video = True,
+    return_for_policy_optimization = True
+)
+
+# learn from the dreams
+
+actor_loss, critic_loss = world_model.learn_from_experience(dreams)
+
+(actor_loss + critic_loss).backward()
+
+# learn from environment
+
+from dreamer4.mocks import MockEnv
+
+mock_env = MockEnv((256, 256), vectorized = True, num_envs = 4)
+
+experience = world_model.interact_with_env(mock_env, max_timesteps = 8, env_is_vectorized = True)
+
+actor_loss, critic_loss = world_model.learn_from_experience(experience)
+
+(actor_loss + critic_loss).backward()
+```
 
 ## Citation
 
@@ -20,11 +109,4 @@ Implementation of Danijar's [latest iteration](https://arxiv.org/abs/2509.24527v
 }
 ```
 
-```bibtex
+*the conquest of nature is to be achieved through number and measure - angels to Descartes in a dream*
-@misc{xiong2025ndrope,
-    author = {Jerry Xiong},
-    title  = {On n-dimensional rotary positional embeddings},
-    year   = {2025},
-    url    = {https://jerryxio.ng/posts/nd-rope/}
-}
-```

dreamer4/__init__.py

@@ -1,5 +1,12 @@
 from dreamer4.dreamer4 import (
     VideoTokenizer,
     DynamicsWorldModel,
-    Dreamer
+    AxialSpaceTimeTransformer
+)
+
+
+from dreamer4.trainers import (
+    VideoTokenizerTrainer,
+    BehaviorCloneTrainer,
+    DreamTrainer
 )

dreamer4/mocks.py

@@ -0,0 +1,97 @@
+from __future__ import annotations
+from random import choice
+
+import torch
+from torch import tensor, empty, randn, randint
+from torch.nn import Module
+
+from einops import repeat
+
+# helpers
+
+def exists(v):
+    return v is not None
+
+# mock env
+
+class MockEnv(Module):
+    def __init__(
+        self,
+        image_shape,
+        reward_range = (-100, 100),
+        num_envs = 1,
+        vectorized = False,
+        terminate_after_step = None,
+        rand_terminate_prob = 0.05,
+        can_truncate = False,
+        rand_truncate_prob = 0.05,
+    ):
+        super().__init__()
+        self.image_shape = image_shape
+        self.reward_range = reward_range
+
+        self.num_envs = num_envs
+        self.vectorized = vectorized
+        assert not (vectorized and num_envs == 1)
+
+        # mocking termination and truncation
+
+        self.can_terminate = exists(terminate_after_step)
+        self.terminate_after_step = terminate_after_step
+        self.rand_terminate_prob = rand_terminate_prob
+
+        self.can_truncate = can_truncate
+        self.rand_truncate_prob = rand_truncate_prob
+
+        self.register_buffer('_step', tensor(0))
+
+    def get_random_state(self):
+        return randn(3, *self.image_shape)
+
+    def reset(
+        self,
+        seed = None
+    ):
+        self._step.zero_()
+        state = self.get_random_state()
+
+        if self.vectorized:
+            state = repeat(state, '... -> b ...', b = self.num_envs)
+
+        return state
+
+    def step(
+        self,
+        actions,
+    ):
+        state = self.get_random_state()
+
+        reward = empty(()).uniform_(*self.reward_range)
+
+        if self.vectorized:
+            discrete, continuous = actions
+            assert discrete.shape[0] == self.num_envs, f'expected batch of actions for {self.num_envs} environments'
+
+            state = repeat(state, '... -> b ...', b = self.num_envs)
+            reward = repeat(reward, ' -> b', b = self.num_envs)
+
+        out = (state, reward)
+
+
+        if self.can_terminate:
+            shape = (self.num_envs,) if self.vectorized else (1,)
+            valid_step = self._step > self.terminate_after_step
+
+            terminate = (torch.rand(shape) < self.rand_terminate_prob) & valid_step
+
+            out = (*out, terminate)
+
+            # maybe truncation
+
+            if self.can_truncate:
+                truncate = (torch.rand(shape) < self.rand_truncate_prob) & valid_step & ~terminate
+                out = (*out, truncate)
+
+        self._step.add_(1)
+
+        return out

dreamer4/trainers.py

@@ -1,17 +1,539 @@
+from __future__ import annotations
+
 import torch
+from torch import is_tensor
 from torch.nn import Module
+from torch.optim import AdamW
+from torch.utils.data import Dataset, TensorDataset, DataLoader
 
 from accelerate import Accelerator
 
+from adam_atan2_pytorch import MuonAdamAtan2
+
 from dreamer4.dreamer4 import (
     VideoTokenizer,
-    DynamicsModel
+    DynamicsWorldModel,
+    Experience,
+    combine_experiences
 )
 
+from ema_pytorch import EMA
+
+# helpers
+
+def exists(v):
+    return v is not None
+
+def default(v, d):
+    return v if exists(v) else d
+
+def cycle(dl):
+    while True:
+        for batch in dl:
+            yield batch
+
+# trainers
+
 class VideoTokenizerTrainer(Module):
     def __init__(
         self,
-        model: VideoTokenizer
+        model: VideoTokenizer,
+        dataset: Dataset,
+        optim_klass = MuonAdamAtan2,
+        batch_size = 16,
+        learning_rate = 3e-4,
+        max_grad_norm = None,
+        num_train_steps = 10_000,
+        weight_decay = 0.,
+        accelerate_kwargs: dict = dict(),
+        optim_kwargs: dict = dict(),
+        cpu = False,
     ):
         super().__init__()
-        raise NotImplementedError
+        batch_size = min(batch_size, len(dataset))
+
+        self.accelerator = Accelerator(
+            cpu = cpu,
+            **accelerate_kwargs
+        )
+
+        self.model = model
+        self.dataset = dataset
+        self.train_dataloader = DataLoader(dataset, batch_size = batch_size, drop_last = True, shuffle = True)
+
+        optim_kwargs = dict(
+            lr = learning_rate,
+            weight_decay = weight_decay
+        )
+
+        if optim_klass is MuonAdamAtan2:
+            optim = MuonAdamAtan2(
+                model.muon_parameters(),
+                model.parameters(),
+                **optim_kwargs
+            )
+        else:
+            optim = optim_klass(
+                model.parameters(),
+                **optim_kwargs
+            )
+
+        self.optim = optim
+
+        self.max_grad_norm = max_grad_norm
+
+        self.num_train_steps = num_train_steps
+        self.batch_size = batch_size
+
+        (
+            self.model,
+            self.train_dataloader,
+            self.optim
+        ) = self.accelerator.prepare(
+            self.model,
+            self.train_dataloader,
+            self.optim
+        )
+
+    @property
+    def device(self):
+        return self.accelerator.device
+
+    def print(self, *args, **kwargs):
+        return self.accelerator.print(*args, **kwargs)
+
+    def forward(
+        self
+    ):
+        iter_train_dl = cycle(self.train_dataloader)
+
+        for _ in range(self.num_train_steps):
+            video = next(iter_train_dl)
+
+            loss = self.model(video)
+            self.accelerator.backward(loss)
+
+            if exists(self.max_grad_norm):
+                self.accelerator.clip_grad_norm_(self.model.parameters(), self.max_grad_norm)
+
+            self.optim.step()
+            self.optim.zero_grad()
+
+        self.print('training complete')
+
+# dynamics world model
+
+class BehaviorCloneTrainer(Module):
+    def __init__(
+        self,
+        model: DynamicsWorldModel,
+        dataset: Dataset,
+        optim_klass = MuonAdamAtan2,
+        batch_size = 16,
+        learning_rate = 3e-4,
+        max_grad_norm = None,
+        num_train_steps = 10_000,
+        weight_decay = 0.,
+        accelerate_kwargs: dict = dict(),
+        optim_kwargs: dict = dict(),
+        cpu = False,
+    ):
+        super().__init__()
+        batch_size = min(batch_size, len(dataset))
+
+        self.accelerator = Accelerator(
+            cpu = cpu,
+            **accelerate_kwargs
+        )
+
+        self.model = model
+        self.dataset = dataset
+        self.train_dataloader = DataLoader(dataset, batch_size = batch_size, drop_last = True, shuffle = True)
+
+        optim_kwargs = dict(
+            lr = learning_rate,
+            weight_decay = weight_decay
+        )
+
+        if optim_klass is MuonAdamAtan2:
+            optim = MuonAdamAtan2(
+                model.muon_parameters(),
+                model.parameters(),
+                **optim_kwargs
+            )
+        else:
+            optim = optim_klass(
+                model.parameters(),
+                **optim_kwargs
+            )
+
+        self.optim = optim
+
+        self.max_grad_norm = max_grad_norm
+
+        self.num_train_steps = num_train_steps
+        self.batch_size = batch_size
+
+        (
+            self.model,
+            self.train_dataloader,
+            self.optim
+        ) = self.accelerator.prepare(
+            self.model,
+            self.train_dataloader,
+            self.optim
+        )
+
+    @property
+    def device(self):
+        return self.accelerator.device
+
+    def print(self, *args, **kwargs):
+        return self.accelerator.print(*args, **kwargs)
+
+    def forward(
+        self
+    ):
+        iter_train_dl = cycle(self.train_dataloader)
+
+        for _ in range(self.num_train_steps):
+            batch_data = next(iter_train_dl)
+
+            # just assume raw video dynamics training if batch_data is a tensor
+            # else kwargs for video, actions, rewards
+
+            if is_tensor(batch_data):
+                loss = self.model(batch_data)
+            else:
+                loss = self.model(**batch_data)
+
+            self.accelerator.backward(loss)
+
+            if exists(self.max_grad_norm):
+                self.accelerator.clip_grad_norm_(self.model.parameters(), self.max_grad_norm)
+
+            self.optim.step()
+            self.optim.zero_grad()
+
+        self.print('training complete')
+
+# training from dreams
+
+class DreamTrainer(Module):
+    def __init__(
+        self,
+        model: DynamicsWorldModel,
+        optim_klass = AdamW,
+        batch_size = 16,
+        generate_timesteps = 16,
+        learning_rate = 3e-4,
+        max_grad_norm = None,
+        num_train_steps = 10_000,
+        weight_decay = 0.,
+        accelerate_kwargs: dict = dict(),
+        optim_kwargs: dict = dict(),
+        cpu = False,
+    ):
+        super().__init__()
+
+        self.accelerator = Accelerator(
+            cpu = cpu,
+            **accelerate_kwargs
+        )
+
+        self.model = model
+
+        optim_kwargs = dict(
+            lr = learning_rate,
+            weight_decay = weight_decay
+        )
+
+        self.policy_head_optim = AdamW(model.policy_head_parameters(), **optim_kwargs)
+        self.value_head_optim = AdamW(model.value_head_parameters(), **optim_kwargs)
+
+        self.max_grad_norm = max_grad_norm
+
+        self.num_train_steps = num_train_steps
+        self.batch_size = batch_size
+        self.generate_timesteps = generate_timesteps
+
+        self.unwrapped_model = self.model
+
+        (
+            self.model,
+            self.policy_head_optim,
+            self.value_head_optim,
+        ) = self.accelerator.prepare(
+            self.model,
+            self.policy_head_optim,
+            self.value_head_optim
+        )
+
+    @property
+    def device(self):
+        return self.accelerator.device
+
+    @property
+    def unwrapped_model(self):
+        return self.accelerator.unwrap_model(self.model)
+
+    def print(self, *args, **kwargs):
+        return self.accelerator.print(*args, **kwargs)
+
+    def forward(
+        self
+    ):
+
+        for _ in range(self.num_train_steps):
+
+            dreams = self.unwrapped_model.generate(
+                self.generate_timesteps + 1, # plus one for bootstrap value
+                batch_size = self.batch_size,
+                return_rewards_per_frame = True,
+                return_agent_actions = True,
+                return_log_probs_and_values = True
+            )
+
+            policy_head_loss, value_head_loss = self.model.learn_from_experience(dreams)
+
+            self.print(f'policy head loss: {policy_head_loss.item():.3f} | value head loss: {value_head_loss.item():.3f}')
+
+            # update policy head
+
+            self.accelerator.backward(policy_head_loss)
+
+            if exists(self.max_grad_norm):
+                self.accelerator.clip_grad_norm_(self.model.policy_head_parameters()(), self.max_grad_norm)
+
+            self.policy_head_optim.step()
+            self.policy_head_optim.zero_grad()
+
+            # update value head
+
+            self.accelerator.backward(value_head_loss)
+
+            if exists(self.max_grad_norm):
+                self.accelerator.clip_grad_norm_(self.model.value_head_parameters(), self.max_grad_norm)
+
+            self.value_head_optim.step()
+            self.value_head_optim.zero_grad()
+
+        self.print('training complete')
+
+# training from sim
+
+class SimTrainer(Module):
+    def __init__(
+        self,
+        model: DynamicsWorldModel,
+        optim_klass = AdamW,
+        batch_size = 16,
+        generate_timesteps = 16,
+        learning_rate = 3e-4,
+        max_grad_norm = None,
+        epochs = 2,
+        weight_decay = 0.,
+        accelerate_kwargs: dict = dict(),
+        optim_kwargs: dict = dict(),
+        cpu = False,
+    ):
+        super().__init__()
+
+        self.accelerator = Accelerator(
+            cpu = cpu,
+            **accelerate_kwargs
+        )
+
+        self.model = model
+
+        optim_kwargs = dict(
+            lr = learning_rate,
+            weight_decay = weight_decay
+        )
+
+        self.policy_head_optim = AdamW(model.policy_head_parameters(), **optim_kwargs)
+        self.value_head_optim = AdamW(model.value_head_parameters(), **optim_kwargs)
+
+        self.max_grad_norm = max_grad_norm
+
+        self.epochs = epochs
+        self.batch_size = batch_size
+
+        self.generate_timesteps = generate_timesteps
+
+        self.unwrapped_model = self.model
+
+        (
+            self.model,
+            self.policy_head_optim,
+            self.value_head_optim,
+        ) = self.accelerator.prepare(
+            self.model,
+            self.policy_head_optim,
+            self.value_head_optim
+        )
+
+    @property
+    def device(self):
+        return self.accelerator.device
+
+    @property
+    def unwrapped_model(self):
+        return self.accelerator.unwrap_model(self.model)
+
+    def print(self, *args, **kwargs):
+        return self.accelerator.print(*args, **kwargs)
+
+    def learn(
+        self,
+        experience: Experience
+    ):
+
+        step_size = experience.step_size
+        agent_index = experience.agent_index
+
+        latents = experience.latents
+        old_values = experience.values
+        rewards = experience.rewards
+
+        has_agent_embed = exists(experience.agent_embed)
+        agent_embed = experience.agent_embed
+
+        discrete_actions, continuous_actions = experience.actions
+        discrete_log_probs, continuous_log_probs = experience.log_probs
+
+        discrete_old_action_unembeds, continuous_old_action_unembeds = default(experience.old_action_unembeds, (None, None))
+
+        # handle empties
+
+        empty_tensor = torch.empty_like(rewards)
+
+        agent_embed = default(agent_embed, empty_tensor)
+
+        has_discrete = exists(discrete_actions)
+        has_continuous = exists(continuous_actions)
+
+        discrete_actions = default(discrete_actions, empty_tensor)
+        continuous_actions = default(continuous_actions, empty_tensor)
+
+        discrete_log_probs = default(discrete_log_probs, empty_tensor)
+        continuous_log_probs = default(continuous_log_probs, empty_tensor)
+
+        discrete_old_action_unembeds = default(discrete_old_action_unembeds, empty_tensor)
+        continuous_old_action_unembeds = default(discrete_old_action_unembeds, empty_tensor)
+
+        # create the dataset and dataloader
+
+        dataset = TensorDataset(
+            latents,
+            discrete_actions,
+            continuous_actions,
+            discrete_log_probs,
+            continuous_log_probs,
+            agent_embed,
+            discrete_old_action_unembeds,
+            continuous_old_action_unembeds,
+            old_values,
+            rewards
+        )
+
+        dataloader = DataLoader(dataset, batch_size = self.batch_size, shuffle = True)
+
+        for epoch in range(self.epochs):
+
+            for (
+                latents,
+                discrete_actions,
+                continuous_actions,
+                discrete_log_probs,
+                continuous_log_probs,
+                agent_embed,
+                discrete_old_action_unembeds,
+                continuous_old_action_unembeds,
+                old_values,
+                rewards
+            ) in dataloader:
+
+                actions = (
+                    discrete_actions if has_discrete else None,
+                    continuous_actions if has_continuous else None
+                )
+
+                log_probs = (
+                    discrete_log_probs if has_discrete else None,
+                    continuous_log_probs if has_continuous else None
+                )
+
+                old_action_unembeds = (
+                    discrete_old_action_unembeds if has_discrete else None,
+                    continuous_old_action_unembeds if has_continuous else None
+                )
+
+                batch_experience = Experience(
+                    latents = latents,
+                    actions = actions,
+                    log_probs = log_probs,
+                    agent_embed = agent_embed if has_agent_embed else None,
+                    old_action_unembeds = old_action_unembeds,
+                    values = old_values,
+                    rewards = rewards,
+                    step_size = step_size,
+                    agent_index = agent_index
+                )
+
+                policy_head_loss, value_head_loss = self.model.learn_from_experience(batch_experience)
+
+                self.print(f'policy head loss: {policy_head_loss.item():.3f} | value head loss: {value_head_loss.item():.3f}')
+
+                # update policy head
+
+                self.accelerator.backward(policy_head_loss)
+
+                if exists(self.max_grad_norm):
+                    self.accelerator.clip_grad_norm_(self.model.policy_head_parameters()(), self.max_grad_norm)
+
+                self.policy_head_optim.step()
+                self.policy_head_optim.zero_grad()
+
+                # update value head
+
+                self.accelerator.backward(value_head_loss)
+
+                if exists(self.max_grad_norm):
+                    self.accelerator.clip_grad_norm_(self.model.value_head_parameters(), self.max_grad_norm)
+
+                self.value_head_optim.step()
+                self.value_head_optim.zero_grad()
+
+        self.print('training complete')
+
+    def forward(
+        self,
+        env,
+        num_episodes = 50000,
+        max_experiences_before_learn = 8,
+        env_is_vectorized = False
+    ):
+
+        for _ in range(num_episodes):
+
+            total_experience = 0
+            experiences = []
+
+            while total_experience < max_experiences_before_learn:
+
+                experience = self.unwrapped_model.interact_with_env(env, env_is_vectorized = env_is_vectorized)
+
+                num_experience = experience.video.shape[0]
+
+                total_experience += num_experience
+
+                experiences.append(experience.cpu())
+
+            combined_experiences = combine_experiences(experiences)
+
+            self.learn(combined_experiences)
+
+            experiences.clear()
+
+        self.print('training complete')

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "dreamer4"
-version = "0.0.19"
+version = "0.1.24"
 description = "Dreamer 4"
 authors = [
     { name = "Phil Wang", email = "lucidrains@gmail.com" }
@@ -31,11 +31,13 @@ dependencies = [
     "assoc-scan",
     "einx>=0.3.0",
     "einops>=0.8.1",
+    "ema-pytorch",
     "hl-gauss-pytorch",
     "hyper-connections>=0.2.1",
     "torch>=2.4",
     "torchvision",
-    "x-mlps-pytorch>=0.0.29"
+    "x-mlps-pytorch>=0.0.29",
+    "vit-pytorch>=1.15.3"
 ]
 
 [project.urls]

tests/test_dreamer.py

@@ -2,6 +2,9 @@ import pytest
 param = pytest.mark.parametrize
 import torch
 
+def exists(v):
+    return v is not None
+
 @param('pred_orig_latent', (False, True))
 @param('grouped_query_attn', (False, True))
 @param('dynamics_with_video_input', (False, True))
@@ -12,6 +15,9 @@ import torch
 @param('condition_on_actions', (False, True))
 @param('num_residual_streams', (1, 4))
 @param('add_reward_embed_to_agent_token', (False, True))
+@param('add_state_pred_head', (False, True))
+@param('use_time_cache', (False, True))
+@param('var_len', (False, True))
 def test_e2e(
     pred_orig_latent,
     grouped_query_attn,
@@ -22,19 +28,24 @@ def test_e2e(
     signal_and_step_passed_in,
     condition_on_actions,
     num_residual_streams,
-    add_reward_embed_to_agent_token
+    add_reward_embed_to_agent_token,
+    add_state_pred_head,
+    use_time_cache,
+    var_len
 ):
     from dreamer4.dreamer4 import VideoTokenizer, DynamicsWorldModel
 
     tokenizer = VideoTokenizer(
         16,
-        encoder_depth = 1,
+        encoder_depth = 4,
-        decoder_depth = 1,
+        decoder_depth = 4,
         dim_latent = 16,
         patch_size = 32,
         attn_dim_head = 16,
         num_latent_tokens = 4,
-        num_residual_streams = num_residual_streams
+        num_residual_streams = num_residual_streams,
+        encoder_add_decor_aux_loss = True,
+        decorr_sample_frac = 1.
     )
 
     video = torch.randn(2, 3, 4, 256, 256)
@@ -62,12 +73,13 @@ def test_e2e(
         pred_orig_latent = pred_orig_latent,
         num_discrete_actions = 4,
         attn_dim_head = 16,
+        attn_heads = heads,
         attn_kwargs = dict(
-            heads = heads,
             query_heads = query_heads,
         ),
         prob_no_shortcut_train = prob_no_shortcut_train,
         add_reward_embed_to_agent_token = add_reward_embed_to_agent_token,
+        add_state_pred_head = add_state_pred_head,
         num_residual_streams = num_residual_streams
     )
 
@@ -88,10 +100,15 @@ def test_e2e(
 
     actions = None
     if condition_on_actions:
-        actions = torch.randint(0, 4, (2, 4, 1))
+        actions = torch.randint(0, 4, (2, 3, 1))
+
+    lens = None
+    if var_len:
+        lens = torch.randint(1, 4, (2,))
 
     flow_loss = dynamics(
         **dynamics_input,
+        lens = lens,
         tasks = tasks,
         signal_levels = signal_levels,
         step_sizes_log2 = step_sizes_log2,
@@ -103,16 +120,17 @@ def test_e2e(
 
     # generating
 
-    generated_video, generated_rewards = dynamics.generate(
+    generations = dynamics.generate(
         time_steps = 10,
         image_height = 128,
         image_width = 128,
         batch_size = 2,
-        return_rewards_per_frame = True
+        return_rewards_per_frame = True,
+        use_time_cache = use_time_cache
     )
 
-    assert generated_video.shape == (2, 3, 10, 128, 128)
+    assert generations.video.shape == (2, 3, 10, 128, 128)
-    assert generated_rewards.shape == (2, 10)
+    assert generations.rewards.shape == (2, 10)
 
     # rl
 
@@ -187,6 +205,63 @@ def test_attend_factory(
 
     assert torch.allclose(flex_out, out, atol = 1e-6)
 
+def test_action_with_world_model():
+    from dreamer4.dreamer4 import VideoTokenizer, DynamicsWorldModel
+
+    tokenizer = VideoTokenizer(
+        512,
+        dim_latent = 32,
+        patch_size = 32,
+        encoder_depth = 4,
+        decoder_depth = 4,
+        attn_heads = 8,
+        image_height = 256,
+        image_width = 256,
+        attn_kwargs = dict(
+            query_heads = 16
+        )
+    )
+
+    dynamics = DynamicsWorldModel(
+        512,
+        num_agents = 1,
+        video_tokenizer = tokenizer,
+        dim_latent = 32,
+        depth = 4,
+        num_discrete_actions = 4
+    )
+
+    rewards = torch.randn(1, 4)
+    discrete_actions = torch.randint(0, 4, (1, 4, 1))
+
+    gen = dynamics.generate(
+        16,
+        batch_size = 4,
+        return_rewards_per_frame = True,
+        return_agent_actions = True,
+        return_log_probs_and_values = True
+    )
+
+    assert gen.video.shape == (4, 3, 16, 256, 256)
+    assert gen.rewards.shape == (4, 16)
+
+    discrete_actions, continuous_actions = gen.actions
+
+    assert discrete_actions.shape == (4, 16, 1)
+    assert continuous_actions is None
+
+    discrete_log_probs, _ = gen.log_probs
+
+    assert discrete_log_probs.shape == (4, 16, 1)
+    assert gen.values.shape == (4, 16)
+
+    # take a reinforcement learning step
+
+    actor_loss, critic_loss = dynamics.learn_from_experience(gen)
+
+    actor_loss.backward(retain_graph = True)
+    critic_loss.backward()
+
 def test_action_embedder():
     from dreamer4.dreamer4 import ActionEmbedder
 
@@ -276,6 +351,15 @@ def test_action_embedder():
     assert discrete_logits.shape == (2, 3, 8)
     assert continuous_mean_log_var.shape == (2, 3, 2, 2)
 
+    # test kl div
+
+    discrete_logits_tgt, continuous_mean_log_var_tgt = embedder.unembed(action_embed)
+
+    discrete_kl_div, continuous_kl_div = embedder.kl_div((discrete_logits, continuous_mean_log_var), (discrete_logits_tgt, continuous_mean_log_var_tgt))
+
+    assert discrete_kl_div.shape == (2, 3)
+    assert continuous_kl_div.shape == (2, 3)
+
     # return discrete split by number of actions
 
     discrete_logits, continuous_mean_log_var = embedder.unembed(action_embed, return_split_discrete = True)
@@ -310,6 +394,17 @@ def test_action_embedder():
     assert discrete_log_probs.shape == (2, 3, 2)
     assert continuous_log_probs.shape == (2, 3, 2)
 
+    _, (discrete_entropies, continuous_entropies) = embedder.log_probs(
+        action_embed,
+        discrete_targets = discrete_actions,
+        continuous_targets = continuous_actions,
+        parallel_discrete_calc = True,
+        return_entropies = True
+    )
+
+    assert discrete_entropies.shape == (2, 3, 2)
+    assert continuous_entropies.shape == (2, 3, 2)
+
     parallel_discrete_log_probs, _ = embedder.log_probs(
         action_embed,
         discrete_targets = discrete_actions,
@@ -318,3 +413,419 @@ def test_action_embedder():
     )
 
     assert torch.allclose(discrete_log_probs, parallel_discrete_log_probs, atol = 1e-5)
+
+def test_mtp():
+    from dreamer4.dreamer4 import create_multi_token_prediction_targets
+
+    rewards = torch.randn(3, 16) # (b t)
+
+    reward_targets, mask = create_multi_token_prediction_targets(rewards, 3) # say three token lookahead
+
+    assert reward_targets.shape == (3, 16, 3)
+    assert mask.shape == (3, 16, 3)
+
+    actions = torch.randint(0, 10, (3, 16, 2))
+    action_targets, mask = create_multi_token_prediction_targets(actions, 3)
+
+    assert action_targets.shape == (3, 16, 3, 2)
+    assert mask.shape == (3, 16, 3)
+
+    from dreamer4.dreamer4 import ActionEmbedder
+
+    embedder = ActionEmbedder(
+        512,
+        num_discrete_actions = (4, 4),
+        num_continuous_actions = 2,
+        can_unembed = True,
+        num_unembed_preds = 8
+    )
+
+    discrete_actions = torch.randint(0, 4, (2, 3, 2))
+    continuous_actions = torch.randn(2, 3, 2)
+
+    action_embed = torch.randn(2, 16, 512)
+    discrete_logits, continuous_logits = embedder.unembed(action_embed)
+
+    assert discrete_logits.shape == (8, 2, 16, 8)
+
+    discrete_logits, continuous_logits = embedder.unembed(action_embed, pred_head_index = 0)
+
+    assert discrete_logits.shape == (2, 16, 8)
+
+def test_loss_normalizer():
+    from torch import cat
+    from dreamer4.dreamer4 import LossNormalizer
+
+    loss_normalizer = LossNormalizer(4, beta = 0.)
+
+    losses = torch.rand(4)
+
+    _ = loss_normalizer(losses)
+    normed_losses = loss_normalizer(losses)
+
+    assert (normed_losses == 1.).all()
+
+def test_tokenizer_trainer():
+    from dreamer4.trainers import VideoTokenizerTrainer
+    from dreamer4.dreamer4 import VideoTokenizer
+    from torch.utils.data import Dataset
+
+    class MockDataset(Dataset):
+        def __len__(self):
+            return 2
+
+        def __getitem__(self, idx):
+            return torch.randn(3, 2, 64, 64)
+
+    dataset = MockDataset()
+
+    tokenizer = VideoTokenizer(
+        16,
+        encoder_depth = 1,
+        decoder_depth = 1,
+        time_block_every = 1,
+        dim_latent = 16,
+        patch_size = 32,
+        attn_dim_head = 16,
+        num_latent_tokens = 4
+    )
+
+    trainer = VideoTokenizerTrainer(
+        tokenizer,
+        dataset = dataset,
+        num_train_steps = 1,
+        batch_size = 1,
+        cpu = True,
+        max_grad_norm = 0.5
+    )
+
+    trainer()
+
+@param('with_actions', (True, False))
+@param('with_rewards', (True, False))
+def test_bc_trainer(
+    with_actions,
+    with_rewards
+):
+    from dreamer4.trainers import BehaviorCloneTrainer
+    from dreamer4.dreamer4 import DynamicsWorldModel, VideoTokenizer
+
+    from torch.utils.data import Dataset
+
+    class MockDataset(Dataset):
+        def __len__(self):
+            return 2
+
+        def __getitem__(self, idx):
+            state = torch.randn(3, 2, 64, 64)
+
+            pkg = dict(video = state)
+
+            if with_actions:
+                pkg.update(discrete_actions = torch.randint(0, 4, (2, 1)))
+
+            if with_rewards:
+                pkg.update(rewards = torch.randn(2,))
+
+            return pkg
+
+    dataset = MockDataset()
+
+    tokenizer = VideoTokenizer(
+        16,
+        encoder_depth = 1,
+        decoder_depth = 1,
+        time_block_every = 1,
+        dim_latent = 16,
+        patch_size = 32,
+        attn_dim_head = 16,
+        num_latent_tokens = 1
+    )
+
+    world_model = DynamicsWorldModel(
+        video_tokenizer = tokenizer,
+        dim = 16,
+        dim_latent = 16,
+        max_steps = 64,
+        num_tasks = 4,
+        num_latent_tokens = 1,
+        depth = 1,
+        time_block_every = 1,
+        num_spatial_tokens = 1,
+        pred_orig_latent = True,
+        num_discrete_actions = 4,
+        attn_dim_head = 16,
+        prob_no_shortcut_train = 0.1,
+        num_residual_streams = 1
+    )
+
+    trainer = BehaviorCloneTrainer(
+        world_model,
+        dataset = dataset,
+        batch_size = 1,
+        num_train_steps = 1,
+        cpu = True
+    )
+
+    trainer()
+
+def test_dream_trainer():
+    from dreamer4.dreamer4 import DynamicsWorldModel
+
+    world_model = DynamicsWorldModel(
+        dim = 16,
+        dim_latent = 16,
+        max_steps = 64,
+        num_tasks = 4,
+        num_latent_tokens = 1,
+        depth = 1,
+        time_block_every = 1,
+        num_spatial_tokens = 1,
+        pred_orig_latent = True,
+        num_discrete_actions = 4,
+        attn_dim_head = 16,
+        prob_no_shortcut_train = 0.1,
+        num_residual_streams = 1
+    )
+
+    # training from self-generations (dreams)
+
+    from dreamer4.trainers import DreamTrainer
+
+    dream_trainer = DreamTrainer(
+        world_model,
+        batch_size = 2,
+        num_train_steps = 1,
+        cpu = True,
+    )
+
+    dream_trainer()
+
+def test_cache_generate():
+    from dreamer4.dreamer4 import DynamicsWorldModel
+
+    dynamics = DynamicsWorldModel(
+        dim = 16,
+        dim_latent = 16,
+        max_steps = 64,
+        num_tasks = 4,
+        num_latent_tokens = 4,
+        depth = 1,
+        time_block_every = 1,
+        num_spatial_tokens = 1,
+        pred_orig_latent = True,
+        num_discrete_actions = 4,
+        attn_dim_head = 16,
+        prob_no_shortcut_train = 0.1,
+        num_residual_streams = 1
+    )
+
+    generated, time_cache = dynamics.generate(1, return_time_cache = True)
+    generated, time_cache = dynamics.generate(1, time_cache = time_cache, return_time_cache = True)
+    generated, time_cache = dynamics.generate(1, time_cache = time_cache, return_time_cache = True)
+
+@param('vectorized', (False, True))
+@param('use_pmpo', (False, True))
+@param('env_can_terminate', (False, True))
+@param('env_can_truncate', (False, True))
+@param('store_agent_embed', (False, True))
+def test_online_rl(
+    vectorized,
+    use_pmpo,
+    env_can_terminate,
+    env_can_truncate,
+    store_agent_embed
+):
+    from dreamer4.dreamer4 import DynamicsWorldModel, VideoTokenizer
+
+    tokenizer = VideoTokenizer(
+        16,
+        encoder_depth = 1,
+        decoder_depth = 1,
+        time_block_every = 1,
+        dim_latent = 16,
+        patch_size = 32,
+        attn_dim_head = 16,
+        num_latent_tokens = 1,
+        image_height = 256,
+        image_width = 256,
+    )
+
+    world_model_and_policy = DynamicsWorldModel(
+        video_tokenizer = tokenizer,
+        dim = 16,
+        dim_latent = 16,
+        max_steps = 64,
+        num_tasks = 4,
+        num_latent_tokens = 1,
+        depth = 1,
+        time_block_every = 1,
+        num_spatial_tokens = 1,
+        pred_orig_latent = True,
+        num_discrete_actions = 4,
+        attn_dim_head = 16,
+        prob_no_shortcut_train = 0.1,
+        num_residual_streams = 1
+    )
+
+    from dreamer4.mocks import MockEnv
+    from dreamer4.dreamer4 import combine_experiences
+
+    mock_env = MockEnv(
+        (256, 256),
+        vectorized = vectorized,
+        num_envs = 4,
+        terminate_after_step = 2 if env_can_terminate else None,
+        can_truncate = env_can_truncate,
+        rand_terminate_prob = 0.1
+    )
+
+    # manually
+
+    dream_experience = world_model_and_policy.generate(10, batch_size = 1, store_agent_embed = store_agent_embed, return_for_policy_optimization = True)
+
+    one_experience = world_model_and_policy.interact_with_env(mock_env, max_timesteps = 8, env_is_vectorized = vectorized, store_agent_embed = store_agent_embed)
+    another_experience = world_model_and_policy.interact_with_env(mock_env, max_timesteps = 16, env_is_vectorized = vectorized, store_agent_embed = store_agent_embed)
+
+    combined_experience = combine_experiences([dream_experience, one_experience, another_experience])
+
+    # quick test moving the experience to different devices
+
+    if torch.cuda.is_available():
+        combined_experience = combined_experience.to(torch.device('cuda'))
+        combined_experience = combined_experience.to(world_model_and_policy.device)
+
+    if store_agent_embed:
+        assert exists(combined_experience.agent_embed)
+
+    actor_loss, critic_loss = world_model_and_policy.learn_from_experience(combined_experience, use_pmpo = use_pmpo)
+
+    actor_loss.backward()
+    critic_loss.backward()
+
+    # with trainer
+
+    from dreamer4.trainers import SimTrainer
+
+    trainer = SimTrainer(
+        world_model_and_policy,
+        batch_size = 4,
+        cpu = True
+    )
+
+    trainer(mock_env, num_episodes = 2, env_is_vectorized = vectorized)
+
+@param('num_video_views', (1, 2))
+def test_proprioception(
+    num_video_views
+):
+    from dreamer4.dreamer4 import VideoTokenizer, DynamicsWorldModel
+
+    tokenizer = VideoTokenizer(
+        512,
+        dim_latent = 32,
+        patch_size = 32,
+        encoder_depth = 2,
+        decoder_depth = 2,
+        time_block_every = 2,
+        attn_heads = 8,
+        image_height = 256,
+        image_width = 256,
+        attn_kwargs = dict(
+            query_heads = 16
+        )
+    )
+
+    dynamics = DynamicsWorldModel(
+        512,
+        num_agents = 1,
+        video_tokenizer = tokenizer,
+        dim_latent = 32,
+        dim_proprio = 21,
+        num_tasks = 4,
+        num_video_views = num_video_views,
+        num_discrete_actions = 4,
+        num_residual_streams = 1
+    )
+
+    if num_video_views > 1:
+        video_shape = (2, num_video_views, 3, 10, 256, 256)
+    else:
+        video_shape = (2, 3, 10, 256, 256)
+
+    video = torch.randn(*video_shape)
+    rewards = torch.randn(2, 10)
+    proprio = torch.randn(2, 10, 21)
+    discrete_actions = torch.randint(0, 4, (2, 10, 1))
+    tasks = torch.randint(0, 4, (2,))
+
+    loss = dynamics(
+        video = video,
+        rewards = rewards,
+        tasks = tasks,
+        proprio = proprio,
+        discrete_actions = discrete_actions
+    )
+
+    loss.backward()
+
+    generations = dynamics.generate(
+        10,
+        batch_size = 2,
+        return_decoded_video = True
+    )
+
+    assert exists(generations.proprio)
+    assert generations.video.shape == video_shape
+
+def test_epo():
+    from dreamer4.dreamer4 import VideoTokenizer, DynamicsWorldModel
+
+    tokenizer = VideoTokenizer(
+        512,
+        dim_latent = 32,
+        patch_size = 32,
+        encoder_depth = 2,
+        decoder_depth = 2,
+        time_block_every = 2,
+        attn_heads = 8,
+        image_height = 256,
+        image_width = 256,
+        attn_kwargs = dict(
+            query_heads = 16
+        )
+    )
+
+    dynamics = DynamicsWorldModel(
+        512,
+        num_agents = 1,
+        video_tokenizer = tokenizer,
+        dim_latent = 32,
+        dim_proprio = 21,
+        num_tasks = 4,
+        num_latent_genes = 16,
+        num_discrete_actions = 4,
+        num_residual_streams = 1
+    )
+
+    fitness = torch.randn(16,)
+    dynamics.evolve_(fitness)
+
+def test_images_to_video_tokenizer():
+    import torch
+    from dreamer4 import VideoTokenizer, DynamicsWorldModel, AxialSpaceTimeTransformer
+
+    tokenizer = VideoTokenizer(
+        dim = 512,
+        dim_latent = 32,
+        patch_size = 32,
+        image_height = 256,
+        image_width = 256,
+        encoder_add_decor_aux_loss = True
+    )
+
+    images = torch.randn(2, 3, 256, 256)
+    loss, (losses, recon_images) = tokenizer(images, return_intermediates = True)
+    loss.backward()
+
+    assert images.shape == recon_images.shape