diff --git a/hackable_diffusion/lib/architecture/arch_typing.py b/hackable_diffusion/lib/architecture/arch_typing.py
index 0a8cd8d..5a8264d 100644
--- a/hackable_diffusion/lib/architecture/arch_typing.py
+++ b/hackable_diffusion/lib/architecture/arch_typing.py
@@ -19,6 +19,7 @@
 """
 
 import enum
+from typing import Any
 from typing import Callable, Protocol
 from hackable_diffusion.lib import hd_typing
 import jax
@@ -50,17 +51,6 @@ class EmbeddingMergeMethod(enum.StrEnum):
   CONCAT = "concat"
 
 
-class ConditioningMechanism(enum.StrEnum):
-  """Types of conditioning mechanisms."""
-
-  ADAPTIVE_NORM = "adaptive_norm"
-  CROSS_ATTENTION = "cross_attention"
-  CONCATENATE = "concatenate"
-  SUM = "sum"
-  SELF_CONDITIONING = "self_conditioning"
-  CUSTOM = "custom"
-
-
 class RoPEPositionType(enum.StrEnum):
   """Rotary Position Embedding (RoPE) types."""
 
@@ -95,6 +85,29 @@ class SkipConnectionMethod(enum.StrEnum):
   NORMALIZED_ADD = "normalized_add"
 
 
+################################################################################
+# MARK: Conditioning Mechanism
+################################################################################
+
+
+class ConditioningMechanism(enum.StrEnum):
+  """Types of conditioning mechanisms."""
+
+  ADAPTIVE_NORM = "adaptive_norm"
+  CROSS_ATTENTION = "cross_attention"
+  CONCATENATE = "concatenate"
+  SUM = "sum"
+  SELF_CONDITIONING = "self_conditioning"
+  CUSTOM = "custom"
+
+
+# Conditioning embeddings corresponds to a dictionary with keys corresponding to
+# the specification of a conditioning mechanism. We use `ConditioningMechanism`
+# as a reference for the most common conditioning mechanisms, but the type
+# structure is more flexible to allow for more general conditioning mechanisms.
+ConditioningEmbeddings = dict[str, Any]
+
+
 ################################################################################
 # MARK: Types and protocols
 ################################################################################
@@ -108,7 +121,7 @@ class ConditionalBackbone(Protocol):
   def __call__(
       self,
       x: DataTree,
-      conditioning_embeddings: dict[ConditioningMechanism, Float["batch ..."]],
+      conditioning_embeddings: ConditioningEmbeddings,
       is_training: bool,
   ) -> DataTree:
     ...
diff --git a/hackable_diffusion/lib/architecture/conditioning_encoder.py b/hackable_diffusion/lib/architecture/conditioning_encoder.py
index dc2d973..adfd284 100644
--- a/hackable_diffusion/lib/architecture/conditioning_encoder.py
+++ b/hackable_diffusion/lib/architecture/conditioning_encoder.py
@@ -42,6 +42,7 @@
 
 ConditioningMechanism = arch_typing.ConditioningMechanism
 EmbeddingMergeMethod = arch_typing.EmbeddingMergeMethod
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 
 ################################################################################
 # MARK: Base classes
@@ -76,7 +77,7 @@ def __call__(
       time: hd_typing.TimeArray,
       conditioning: hd_typing.Conditioning | None,
       is_training: bool,
-  ) -> dict[ConditioningMechanism, Float['batch ...']]:
+  ) -> ConditioningEmbeddings:
     ...
 
 
@@ -342,6 +343,28 @@ def __call__(
 ################################################################################
 
 
+class CopyConditioningEncoder(nn.Module, BaseConditioningEncoder):
+  """Copies the conditioning to the output and optionally encodes time."""
+
+  time_embedder: BaseTimeEmbedder | None = None
+
+  @nn.compact
+  def __call__(
+      self,
+      time: hd_typing.TimeArray,
+      conditioning: hd_typing.Conditioning | None,
+      is_training: bool,
+  ) -> ConditioningEmbeddings:
+    cond_embs = {}
+    if self.time_embedder is not None:
+      cond_embs['time'] = cast(nn.Module, self.time_embedder).copy(
+          name='TimeEmbedder'
+      )(time)
+    if conditioning is not None:
+      cond_embs.update(conditioning)
+    return cond_embs
+
+
 class ConditioningEncoder(nn.Module, BaseConditioningEncoder):
   """Encodes and combines time and conditioning signals for a diffusion model.
 
@@ -392,7 +415,7 @@ class ConditioningEncoder(nn.Module, BaseConditioningEncoder):
   time_embedder: BaseTimeEmbedder
   conditioning_embedders: dict[str, BaseEmbedder]
   embedding_merging_method: EmbeddingMergeMethod
-  conditioning_rules: dict[str, ConditioningMechanism]
+  conditioning_rules: dict[str, str]
   conditioning_dropout_rate: float = 0.0
 
   def setup(self):
@@ -427,7 +450,7 @@ def __call__(
       time: hd_typing.TimeTree,
       conditioning: hd_typing.Conditioning | None,
       is_training: bool,
-  ) -> dict[ConditioningMechanism, Num['batch ...']]:
+  ) -> ConditioningEmbeddings:
     """Encodes and combines time and conditioning signals.
 
     The output is a dictionary where keys are the embedding mechanisms specified
diff --git a/hackable_diffusion/lib/architecture/conditioning_encoder_test.py b/hackable_diffusion/lib/architecture/conditioning_encoder_test.py
index 4b6849b..59d2ad1 100644
--- a/hackable_diffusion/lib/architecture/conditioning_encoder_test.py
+++ b/hackable_diffusion/lib/architecture/conditioning_encoder_test.py
@@ -699,6 +699,80 @@ def test_dropout(self):
         jnp.all(output_eval['adaptive_norm'] == time_embedding_train)
     )
 
+  def test_copy_conditioning_encoder(self):
+    """Tests the CopyConditioningEncoder."""
+    batch_size = 4
+    encoder = conditioning_encoder.CopyConditioningEncoder()
+    t = jnp.ones((batch_size,))
+    conditioning = {
+        'label': jnp.arange(batch_size),
+        'arbitrary_pytree': dict(
+            a=jnp.ones((batch_size, 127, 199)),
+            b=dict(c=jnp.ones((batch_size, 127, 199))),
+        ),
+    }
+    rng = jax.random.PRNGKey(0)
+    variables = encoder.init(rng, t, conditioning, is_training=True)
+    jitted_apply = jax.jit(encoder.apply, static_argnames=['is_training'])
+    output = jitted_apply(
+        variables,
+        t,
+        conditioning,
+        is_training=True,
+        rngs={'dropout': rng},
+    )
+    # Compare the pytree structure and leaves individually.
+    output_leaves, output_treedef = jax.tree.flatten(output)
+    cond_leaves, cond_treedef = jax.tree.flatten(conditioning)
+    self.assertEqual(output_treedef, cond_treedef)
+    for out_leaf, cond_leaf in zip(output_leaves, cond_leaves):
+      self.assertTrue(jnp.array_equal(out_leaf, cond_leaf))
+
+  def test_copy_conditioning_encoder_with_time_embedder(self):
+    """Tests the CopyConditioningEncoder."""
+    batch_size = 4
+    num_features = 17
+    time_embedder = conditioning_encoder.SinusoidalTimeEmbedder(
+        activation='silu',
+        embedding_dim=5,
+        num_features=num_features,
+    )
+
+    encoder = conditioning_encoder.CopyConditioningEncoder(
+        time_embedder=time_embedder
+    )
+    t = jnp.ones((batch_size,))
+    conditioning = {
+        'label': jnp.arange(batch_size),
+        'arbitrary_pytree': dict(
+            a=jnp.ones((batch_size, 127, 199)),
+            b=dict(c=jnp.ones((batch_size, 127, 199))),
+        ),
+    }
+    rng = jax.random.PRNGKey(0)
+    variables = encoder.init(rng, t, conditioning, is_training=True)
+    jitted_apply = jax.jit(encoder.apply, static_argnames=['is_training'])
+    output = jitted_apply(
+        variables,
+        t,
+        conditioning,
+        is_training=True,
+        rngs={'dropout': rng},
+    )
+
+    # Verify all conditioning fields are copied through.
+    for key in conditioning:
+      self.assertIn(key, output)
+      out_leaves, out_td = jax.tree.flatten(output[key])
+      cond_leaves, cond_td = jax.tree.flatten(conditioning[key])
+      self.assertEqual(out_td, cond_td)
+      for out_leaf, cond_leaf in zip(out_leaves, cond_leaves):
+        self.assertTrue(jnp.array_equal(out_leaf, cond_leaf))
+
+    # Verify the time embedding shape.
+    self.assertIn('time', output)
+    self.assertEqual(output['time'].shape, (batch_size, num_features))
+
 
 if __name__ == '__main__':
   absltest.main()
diff --git a/hackable_diffusion/lib/architecture/discrete.py b/hackable_diffusion/lib/architecture/discrete.py
index 77d93ac..d8521a3 100644
--- a/hackable_diffusion/lib/architecture/discrete.py
+++ b/hackable_diffusion/lib/architecture/discrete.py
@@ -33,6 +33,7 @@
 
 ConditionalBackbone = arch_typing.ConditionalBackbone
 ConditioningMechanism = arch_typing.ConditioningMechanism
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 
 ################################################################################
 # MARK: Token Embedder
@@ -213,7 +214,7 @@ def __post_init__(self):
   def __call__(
       self,
       x: Int['batch *other 1'],
-      conditioning_embeddings: dict[ConditioningMechanism, Float['batch ...']],
+      conditioning_embeddings: ConditioningEmbeddings,
       is_training: bool,
   ) -> Float['batch *other V']:
 
diff --git a/hackable_diffusion/lib/architecture/dit.py b/hackable_diffusion/lib/architecture/dit.py
index fec0891..7118153 100644
--- a/hackable_diffusion/lib/architecture/dit.py
+++ b/hackable_diffusion/lib/architecture/dit.py
@@ -40,6 +40,7 @@
 
 ConditionalBackbone = arch_typing.ConditionalBackbone
 ConditioningMechanism = arch_typing.ConditioningMechanism
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 NormalizationType = arch_typing.NormalizationType
 
 ################################################################################
@@ -100,7 +101,7 @@ def setup(self):
   def __call__(
       self,
       x: DataArray,
-      conditioning_embeddings: dict[ConditioningMechanism, Float["batch ..."]],
+      conditioning_embeddings: ConditioningEmbeddings,
       is_training: bool,
   ) -> DataArray:
     adaptive_norm_emb = conditioning_embeddings.get(
diff --git a/hackable_diffusion/lib/architecture/mlp.py b/hackable_diffusion/lib/architecture/mlp.py
index f2c2ab0..8d7d585 100644
--- a/hackable_diffusion/lib/architecture/mlp.py
+++ b/hackable_diffusion/lib/architecture/mlp.py
@@ -38,6 +38,7 @@
 
 ConditionalBackbone = arch_typing.ConditionalBackbone
 ConditioningMechanism = arch_typing.ConditioningMechanism
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 
 ################################################################################
 # MARK: ConditionalMLP
@@ -77,7 +78,7 @@ class ConditionalMLP(nn.Module, ConditionalBackbone):
   def __call__(
       self,
       x: DataArray,
-      conditioning_embeddings: dict[ConditioningMechanism, Float['batch ...']],
+      conditioning_embeddings: ConditioningEmbeddings,
       *,
       is_training: bool,
   ) -> DataArray:
diff --git a/hackable_diffusion/lib/architecture/riemannian.py b/hackable_diffusion/lib/architecture/riemannian.py
index 225e88e..a81677b 100644
--- a/hackable_diffusion/lib/architecture/riemannian.py
+++ b/hackable_diffusion/lib/architecture/riemannian.py
@@ -23,6 +23,7 @@
 ################################################################################
 
 ConditionalBackbone = arch_typing.ConditionalBackbone
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 
 
 class RiemannianConditionalBackbone(nn.Module, ConditionalBackbone):
@@ -35,9 +36,15 @@ class RiemannianConditionalBackbone(nn.Module, ConditionalBackbone):
   manifold: manifolds.Manifold
 
   @nn.compact
-  def __call__(self, x, conditioning_embeddings, is_training=True):
-
-    v = self.backbone(x, conditioning_embeddings, is_training=is_training)
+  def __call__(
+      self, x, conditioning_embeddings: ConditioningEmbeddings, is_training=True
+  ):
+
+    v = self.backbone(
+        x,
+        conditioning_embeddings=conditioning_embeddings,
+        is_training=is_training,
+    )
 
     # Project v to tangent space at xt.
     if isinstance(v, dict) and 'velocity' in v:
diff --git a/hackable_diffusion/lib/architecture/unet.py b/hackable_diffusion/lib/architecture/unet.py
index d8159c5..cef7426 100644
--- a/hackable_diffusion/lib/architecture/unet.py
+++ b/hackable_diffusion/lib/architecture/unet.py
@@ -39,6 +39,7 @@
 SkipConnectionMethod = arch_typing.SkipConnectionMethod
 ConditionalBackbone = arch_typing.ConditionalBackbone
 ConditioningMechanism = arch_typing.ConditioningMechanism
+ConditioningEmbeddings = arch_typing.ConditioningEmbeddings
 
 ################################################################################
 # MARK: Unet
@@ -163,7 +164,7 @@ def setup(self):
   def __call__(
       self,
       x: Float["batch height width channels"],
-      conditioning_embeddings: dict[ConditioningMechanism, Float["batch ..."]],
+      conditioning_embeddings: ConditioningEmbeddings,
       *,
       is_training: bool,
   ) -> Float["batch height width output_channels"]:
diff --git a/hackable_diffusion/lib/test_helpers.py b/hackable_diffusion/lib/test_helpers.py
index fd2b307..2c834c4 100644
--- a/hackable_diffusion/lib/test_helpers.py
+++ b/hackable_diffusion/lib/test_helpers.py
@@ -91,9 +91,7 @@ class IdentityBackbone(nn.Module, arch_typing.ConditionalBackbone):
   def __call__(
       self,
       x: arch_typing.DataTree,
-      conditioning_embeddings: dict[
-          arch_typing.ConditioningMechanism, Float['batch ...']
-      ],
+      conditioning_embeddings: arch_typing.ConditioningEmbeddings,
       is_training: bool,
   ) -> arch_typing.DataTree:
     return x