diff --git a/envs/repl_env/rubrics.py b/envs/repl_env/rubrics.py
index 7c677f6d4..f971bb50d 100644
--- a/envs/repl_env/rubrics.py
+++ b/envs/repl_env/rubrics.py
@@ -21,6 +21,12 @@
 from typing import Any, Callable
 
 from openenv.core.rubrics.base import Rubric
+from openenv.core.rubrics.components import (
+    RewardComponent,
+    RewardComponentType,
+    aggregate_weighted_sum,
+    serialize_reward_components,
+)
 
 
 class ExactMatchRubric(Rubric):
@@ -173,16 +179,61 @@ def set_expected(self, expected: str | None) -> None:
         if hasattr(self.outcome, "set_expected"):
             self.outcome.set_expected(expected)
 
-    def forward(self, action: Any, observation: Any) -> float:
+    def evaluate_components(self, action: Any, observation: Any) -> list[RewardComponent]:
+        """Compute structured reward components for the current step."""
         done = getattr(observation, "done", False)
         if done:
             final = getattr(observation, "metadata", {}).get("final_answer")
             if final is not None:
-                return self.outcome(action, observation)
-            # Done but no final answer (max iterations exhausted)
-            return self.failure_reward
-        # Non-terminal step: process reward only
-        return self.process(action, observation)
+                return [
+                    RewardComponent(
+                        name="outcome_match",
+                        type=RewardComponentType.BINARY,
+                        value=float(self.outcome(action, observation)),
+                        weight=1.0,
+                        terminal_only=True,
+                    )
+                ]
+            return [
+                RewardComponent(
+                    name="max_iterations_failure",
+                    type=RewardComponentType.PENALTY,
+                    value=float(self.failure_reward),
+                    weight=1.0,
+                    terminal_only=True,
+                )
+            ]
+
+        return [
+            RewardComponent(
+                name="code_execution_quality",
+                type=RewardComponentType.SHAPING,
+                value=float(self.process(action, observation)),
+                weight=1.0,
+                terminal_only=False,
+            )
+        ]
+
+    def _attach_reward_metadata(
+        self,
+        observation: Any,
+        components: list[RewardComponent],
+        total: float,
+    ) -> None:
+        """Attach component diagnostics to observation metadata if available."""
+        if not hasattr(observation, "metadata"):
+            return
+        metadata = getattr(observation, "metadata", None) or {}
+        metadata["reward_components"] = serialize_reward_components(components)
+        metadata["reward_total"] = total
+        metadata["reward_aggregation"] = "weighted_sum_v1"
+        observation.metadata = metadata
+
+    def forward(self, action: Any, observation: Any) -> float:
+        components = self.evaluate_components(action, observation)
+        total = aggregate_weighted_sum(components)
+        self._attach_reward_metadata(observation, components, total)
+        return total
 
     def reset(self) -> None:
         self.outcome.reset()
diff --git a/src/openenv/core/rubrics/__init__.py b/src/openenv/core/rubrics/__init__.py
index abe368494..d7a51849c 100644
--- a/src/openenv/core/rubrics/__init__.py
+++ b/src/openenv/core/rubrics/__init__.py
@@ -10,6 +10,12 @@
 """
 
 from openenv.core.rubrics.base import Rubric
+from openenv.core.rubrics.components import (
+    RewardComponent,
+    RewardComponentType,
+    aggregate_weighted_sum,
+    serialize_reward_components,
+)
 from openenv.core.rubrics.containers import (
     Gate,
     RubricDict,
@@ -26,6 +32,11 @@
 __all__ = [
     # Base
     "Rubric",
+    # Components
+    "RewardComponent",
+    "RewardComponentType",
+    "aggregate_weighted_sum",
+    "serialize_reward_components",
     # Containers
     "Sequential",
     "Gate",
diff --git a/src/openenv/core/rubrics/components.py b/src/openenv/core/rubrics/components.py
new file mode 100644
index 000000000..23bab094e
--- /dev/null
+++ b/src/openenv/core/rubrics/components.py
@@ -0,0 +1,65 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""Reward component schema and helpers.
+
+This module provides a standard representation for decomposed reward signals
+while preserving a scalar optimization target.
+"""
+
+from enum import Enum
+from typing import Any, Dict, List
+
+from pydantic import BaseModel, ConfigDict, Field
+
+
+class RewardComponentType(str, Enum):
+    """Common reward component styles for training diagnostics."""
+
+    BINARY = "binary"
+    SPARSE = "sparse"
+    DENSE = "dense"
+    SHAPING = "shaping"
+    PENALTY = "penalty"
+
+
+class RewardComponent(BaseModel):
+    """Structured reward component emitted by a rubric/environment."""
+
+    model_config = ConfigDict(extra="forbid")
+
+    name: str = Field(..., description="Stable component identifier")
+    type: RewardComponentType = Field(..., description="Reward component style")
+    value: float = Field(..., description="Raw component value before weighting")
+    weight: float = Field(default=1.0, description="Aggregation weight")
+    weighted_value: float | None = Field(
+        default=None,
+        description="Optional explicit weighted value (defaults to value * weight)",
+    )
+    terminal_only: bool = Field(
+        default=False,
+        description="Whether this component is meaningful only at terminal steps",
+    )
+    metadata: Dict[str, Any] = Field(
+        default_factory=dict,
+        description="Additional component-specific diagnostics",
+    )
+
+    def effective_weighted_value(self) -> float:
+        """Return weighted component value, respecting explicit overrides."""
+        if self.weighted_value is not None:
+            return self.weighted_value
+        return self.value * self.weight
+
+
+def aggregate_weighted_sum(components: List[RewardComponent]) -> float:
+    """Aggregate reward components with weighted-sum semantics."""
+    return float(sum(component.effective_weighted_value() for component in components))
+
+
+def serialize_reward_components(components: List[RewardComponent]) -> List[Dict[str, Any]]:
+    """Serialize reward components for observation metadata."""
+    return [component.model_dump() for component in components]
diff --git a/tests/core/test_rubrics/test_reward_components.py b/tests/core/test_rubrics/test_reward_components.py
new file mode 100644
index 000000000..156d3fa16
--- /dev/null
+++ b/tests/core/test_rubrics/test_reward_components.py
@@ -0,0 +1,68 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+"""Tests for reward component schema and helpers."""
+
+from openenv.core.rubrics.components import (
+    RewardComponent,
+    RewardComponentType,
+    aggregate_weighted_sum,
+    serialize_reward_components,
+)
+
+
+class TestRewardComponent:
+    def test_weighted_value_defaults_to_value_times_weight(self):
+        component = RewardComponent(
+            name="progress",
+            type=RewardComponentType.DENSE,
+            value=0.6,
+            weight=0.5,
+        )
+        assert component.effective_weighted_value() == 0.3
+
+    def test_explicit_weighted_value_takes_precedence(self):
+        component = RewardComponent(
+            name="safety_penalty",
+            type=RewardComponentType.PENALTY,
+            value=-1.0,
+            weight=0.2,
+            weighted_value=-0.5,
+        )
+        assert component.effective_weighted_value() == -0.5
+
+
+class TestRewardComponentHelpers:
+    def test_aggregate_weighted_sum(self):
+        components = [
+            RewardComponent(
+                name="success",
+                type=RewardComponentType.BINARY,
+                value=1.0,
+                weight=0.7,
+            ),
+            RewardComponent(
+                name="format",
+                type=RewardComponentType.SPARSE,
+                value=1.0,
+                weight=0.3,
+            ),
+        ]
+        assert aggregate_weighted_sum(components) == 1.0
+
+    def test_serialize_reward_components(self):
+        components = [
+            RewardComponent(
+                name="step_quality",
+                type=RewardComponentType.SHAPING,
+                value=-0.05,
+            )
+        ]
+        payload = serialize_reward_components(components)
+        assert len(payload) == 1
+        assert payload[0]["name"] == "step_quality"
+        assert payload[0]["type"] == "shaping"
+        assert payload[0]["value"] == -0.05
diff --git a/tests/envs/test_repl_env.py b/tests/envs/test_repl_env.py
index 4811119fb..855770665 100644
--- a/tests/envs/test_repl_env.py
+++ b/tests/envs/test_repl_env.py
@@ -289,6 +289,13 @@ def test_rubric_reward_on_success(self):
         obs = env.step(REPLAction(code="print('FINAL(done)')"))
         assert obs.done
         assert obs.reward == 1.0
+        assert obs.metadata["reward_total"] == 1.0
+        assert obs.metadata["reward_aggregation"] == "weighted_sum_v1"
+        assert len(obs.metadata["reward_components"]) == 1
+        component = obs.metadata["reward_components"][0]
+        assert component["name"] == "outcome_match"
+        assert component["type"] == "binary"
+        assert component["terminal_only"] is True
 
     def test_rubric_reward_on_wrong_answer(self):
         """Test rubric reward when final answer does not match expected."""
@@ -299,6 +306,9 @@ def test_rubric_reward_on_wrong_answer(self):
         obs = env.step(REPLAction(code="print('FINAL(wrong)')"))
         assert obs.done
         assert obs.reward == 0.0
+        assert obs.metadata["reward_total"] == 0.0
+        assert obs.metadata["reward_components"][0]["name"] == "outcome_match"
+        assert obs.metadata["reward_components"][0]["type"] == "binary"
 
     def test_rubric_reward_on_error(self):
         """Test rubric process reward on code error."""
@@ -306,6 +316,10 @@ def test_rubric_reward_on_error(self):
         env.reset()
         obs = env.step(REPLAction(code="raise ValueError()"))
         assert obs.reward == -0.05  # default CodeExecutionRubric error_penalty
+        assert obs.metadata["reward_total"] == -0.05
+        assert obs.metadata["reward_components"][0]["name"] == "code_execution_quality"
+        assert obs.metadata["reward_components"][0]["type"] == "shaping"
+        assert obs.metadata["reward_components"][0]["terminal_only"] is False
 
     def test_close(self):
         """Test close cleans up resources."""