diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index d3dc6f4b1..a8ef3c4a4 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -28,6 +28,12 @@ BC-Bench is category-based and designed to grow over time. It currently has two
 - Prefer high-order functions like map, filter, reduce over loops
 - Prefer immutable data structures where possible
 
+### Architecture design conventions
+
+Preserve one-way dependency flow from orchestration toward lower-level abstractions. Keep domain and result models independent of runtime code. CLI commands are composition roots: they select concrete agents and inject them into evaluation pipelines through `AgentRunner`; pipelines must not select agent implementations.
+
+`bcbench.types` is the central category registry. Extend `EvaluationCategory` for category-owned mappings such as datasets, pipelines, results, and scoring behavior instead of duplicating those decisions elsewhere. Keep imports following the existing direction and avoid circular dependencies.
+
 ### Readable code over documentation or comments
 Function names should be self-explanatory. Do NOT add docstrings to functions unless absolutely necessary.
 When a docstring is necessary, keep it short and use Google style. Include only useful sections such as `Args:` and `Returns:`; skip details that are obvious from names and type hints.
diff --git a/pyproject.toml b/pyproject.toml
index 4023d8ccd..12b3126f5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -89,6 +89,9 @@ extend-select = [
     "RSE",   # flake8-raise: drop redundant parentheses on bare exception raises
     "PGH",   # pygrep-hooks: require codes on noqa/type-ignore comments (PGH003/PGH004)
     "S307",  # flake8-bandit: ban eval (was PGH001, which ruff removed in favour of this rule)
+    "DTZ",   # flake8-datetimez: require timezone-aware datetime usage
+    "NPY",   # NumPy-specific correctness and modernization checks
+    "PIE",   # flake8-pie: miscellaneous correctness and simplification checks
 ]
 
 ignore = [
@@ -98,6 +101,9 @@ ignore = [
     "TRY003",  # raise-vanilla-args: forces a custom exception class for every error message (96 sites)
 ]
 
+[tool.ruff.lint.flake8-tidy-imports]
+ban-relative-imports = "all"
+
 [tool.ruff.lint.flake8-tidy-imports.banned-api]
 # Force sandboxed rendering:
 "jinja2.Template".msg = "Use jinja2.sandbox.SandboxedEnvironment instead; the bare Template is not sandboxed."
diff --git a/src/bcbench/commands/evaluate.py b/src/bcbench/commands/evaluate.py
index 6aa1dcbc7..101b8b92c 100644
--- a/src/bcbench/commands/evaluate.py
+++ b/src/bcbench/commands/evaluate.py
@@ -1,6 +1,5 @@
 import random
 import shutil
-from collections.abc import Callable
 from pathlib import Path
 from typing import Annotated, cast
 
@@ -22,7 +21,7 @@
 )
 from bcbench.config import get_config
 from bcbench.dataset import BaseDatasetEntry, NL2ALEntry
-from bcbench.evaluate import EvaluationPipeline
+from bcbench.evaluate import AgentRunner, EvaluationPipeline
 from bcbench.evaluate.codereview_judge_calibration import run_calibration
 from bcbench.logger import get_logger
 from bcbench.results import BaseEvaluationResult, CodeReviewResult, ExecutionBasedEvaluationResult, JudgeBasedEvaluationResult
@@ -335,7 +334,7 @@ def setup_workspace(self, entry: BaseDatasetEntry, repo_path: Path) -> None:
     def setup(self, context: EvaluationContext[BaseDatasetEntry]) -> None:
         logger.info("Mock pipeline: Skipping setup")
 
-    def run_agent(self, context: EvaluationContext[BaseDatasetEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[BaseDatasetEntry], agent_runner: AgentRunner[BaseDatasetEntry]) -> None:
         """Generate random agent metrics and experiment configuration."""
         logger.info("Mock pipeline: Generating random metrics and experiment configuration")
 
diff --git a/src/bcbench/evaluate/__init__.py b/src/bcbench/evaluate/__init__.py
index fd15bd584..c9c63ee90 100644
--- a/src/bcbench/evaluate/__init__.py
+++ b/src/bcbench/evaluate/__init__.py
@@ -1,6 +1,6 @@
 """Evaluation module for running pipelines and creating results."""
 
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.evaluate.bugfix import BugFixPipeline
 from bcbench.evaluate.codereview import CodeReviewPipeline
 from bcbench.evaluate.ext_request_advisor import ExtRequestAdvisorPipeline
@@ -10,6 +10,7 @@
 from bcbench.evaluate.testgeneration import TestGenerationPipeline
 
 __all__ = [
+    "AgentRunner",
     "BugFixPipeline",
     "CodeReviewPipeline",
     "EvaluationPipeline",
diff --git a/src/bcbench/evaluate/base.py b/src/bcbench/evaluate/base.py
index bdd1542ae..2eaf427bd 100644
--- a/src/bcbench/evaluate/base.py
+++ b/src/bcbench/evaluate/base.py
@@ -1,8 +1,8 @@
 from __future__ import annotations
 
 from abc import ABC, abstractmethod
-from collections.abc import Callable
 from pathlib import Path
+from typing import Protocol
 
 from bcbench.config import get_config
 from bcbench.dataset import BaseDatasetEntry
@@ -14,7 +14,11 @@
 logger = get_logger(__name__)
 _config = get_config()
 
-__all__ = ["EvaluationPipeline"]
+__all__ = ["AgentRunner", "EvaluationPipeline"]
+
+
+class AgentRunner[E: BaseDatasetEntry](Protocol):
+    def __call__(self, context: EvaluationContext[E], /) -> tuple[AgentMetrics | None, ExperimentConfiguration | None]: ...
 
 
 class EvaluationPipeline[E: BaseDatasetEntry](ABC):
@@ -45,7 +49,7 @@ def setup(self, context: EvaluationContext[E]) -> None:
         raise NotImplementedError
 
     @abstractmethod
-    def run_agent(self, context: EvaluationContext[E], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[E], agent_runner: AgentRunner[E]) -> None:
         """Run the agent and capture metrics.
 
         Args:
@@ -74,7 +78,7 @@ def evaluate(self, context: EvaluationContext[E]) -> None:
     def execute(
         self,
         context: EvaluationContext[E],
-        agent_runner: Callable[[EvaluationContext[E]], tuple[AgentMetrics | None, ExperimentConfiguration | None]],
+        agent_runner: AgentRunner[E],
     ) -> None:
         """Template method orchestrating the evaluation flow.
 
diff --git a/src/bcbench/evaluate/bugfix.py b/src/bcbench/evaluate/bugfix.py
index 625319b18..acc1c9838 100644
--- a/src/bcbench/evaluate/bugfix.py
+++ b/src/bcbench/evaluate/bugfix.py
@@ -1,8 +1,7 @@
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset import BugFixEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.exceptions import BuildError, TestExecutionError
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
@@ -46,7 +45,7 @@ def setup(self, context: EvaluationContext[BugFixEntry]) -> None:
         copy_problem_statement_folder(context.entry, context.repo_path)
         set_runtime_version(context.repo_path, context.entry.project_paths)
 
-    def run_agent(self, context: EvaluationContext[BugFixEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[BugFixEntry], agent_runner: AgentRunner[BugFixEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/src/bcbench/evaluate/codereview.py b/src/bcbench/evaluate/codereview.py
index 62c167c64..fefbdc05a 100644
--- a/src/bcbench/evaluate/codereview.py
+++ b/src/bcbench/evaluate/codereview.py
@@ -1,9 +1,8 @@
 import subprocess
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset.codereview import CodeReviewEntry, ReviewComment
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.evaluate.codereview_judge import judge_expected_and_ignored
 from bcbench.evaluate.review_parsing import parse_review_output
 from bcbench.github_actions import github_log_group
@@ -50,7 +49,7 @@ def setup_workspace(self, entry: CodeReviewEntry, repo_path: Path) -> None:
     def setup(self, context: EvaluationContext[CodeReviewEntry]) -> None:
         self.setup_workspace(context.entry, context.repo_path)
 
-    def run_agent(self, context: EvaluationContext[CodeReviewEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[CodeReviewEntry], agent_runner: AgentRunner[CodeReviewEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/src/bcbench/evaluate/ext_request_advisor.py b/src/bcbench/evaluate/ext_request_advisor.py
index c8ecddcf9..4ce32f92d 100644
--- a/src/bcbench/evaluate/ext_request_advisor.py
+++ b/src/bcbench/evaluate/ext_request_advisor.py
@@ -1,8 +1,7 @@
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset import ExtRequestAdvisorEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
 from bcbench.operations import setup_repo_prebuild
@@ -26,7 +25,7 @@ def setup_workspace(self, entry: ExtRequestAdvisorEntry, repo_path: Path) -> Non
     def setup(self, context: EvaluationContext[ExtRequestAdvisorEntry]) -> None:
         self.setup_workspace(context.entry, context.repo_path)
 
-    def run_agent(self, context: EvaluationContext[ExtRequestAdvisorEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[ExtRequestAdvisorEntry], agent_runner: AgentRunner[ExtRequestAdvisorEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/src/bcbench/evaluate/ext_request_implement.py b/src/bcbench/evaluate/ext_request_implement.py
index de4a04d22..23b4f40b6 100644
--- a/src/bcbench/evaluate/ext_request_implement.py
+++ b/src/bcbench/evaluate/ext_request_implement.py
@@ -1,8 +1,7 @@
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset import ExtRequestImplementEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.exceptions import EmptyDiffError
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
@@ -31,7 +30,7 @@ def setup_workspace(self, entry: ExtRequestImplementEntry, repo_path: Path) -> N
     def setup(self, context: EvaluationContext[ExtRequestImplementEntry]) -> None:
         self.setup_workspace(context.entry, context.repo_path)
 
-    def run_agent(self, context: EvaluationContext[ExtRequestImplementEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[ExtRequestImplementEntry], agent_runner: AgentRunner[ExtRequestImplementEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/src/bcbench/evaluate/ext_request_triage.py b/src/bcbench/evaluate/ext_request_triage.py
index 2a3f7b7cb..f2539cdfc 100644
--- a/src/bcbench/evaluate/ext_request_triage.py
+++ b/src/bcbench/evaluate/ext_request_triage.py
@@ -8,11 +8,10 @@
 `expected` checklist.
 """
 
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset import ExtRequestTriageEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
 from bcbench.operations import setup_repo_prebuild
@@ -36,7 +35,7 @@ def setup_workspace(self, entry: ExtRequestTriageEntry, repo_path: Path) -> None
     def setup(self, context: EvaluationContext[ExtRequestTriageEntry]) -> None:
         self.setup_workspace(context.entry, context.repo_path)
 
-    def run_agent(self, context: EvaluationContext[ExtRequestTriageEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[ExtRequestTriageEntry], agent_runner: AgentRunner[ExtRequestTriageEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/src/bcbench/evaluate/nl2al.py b/src/bcbench/evaluate/nl2al.py
index cc704a204..157bf4edf 100644
--- a/src/bcbench/evaluate/nl2al.py
+++ b/src/bcbench/evaluate/nl2al.py
@@ -1,10 +1,9 @@
 import os
 import subprocess
-from collections.abc import Callable
 from pathlib import Path
 
 from bcbench.dataset import NL2ALEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.exceptions import EmptyDiffError
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
@@ -52,7 +51,7 @@ def setup_workspace(self, entry: NL2ALEntry, repo_path: Path) -> None:
     def setup(self, context: EvaluationContext[NL2ALEntry]) -> None:
         self.setup_workspace(context.entry, context.repo_path)
 
-    def run_agent(self, context: EvaluationContext[NL2ALEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[NL2ALEntry], agent_runner: AgentRunner[NL2ALEntry]) -> None:
         for attempt in range(1, _EMPTY_DIFF_MAX_ATTEMPTS + 1):
             with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id} (attempt {attempt}/{_EMPTY_DIFF_MAX_ATTEMPTS})"):
                 context.metrics, context.experiment = agent_runner(context)
diff --git a/src/bcbench/evaluate/testgeneration.py b/src/bcbench/evaluate/testgeneration.py
index 7c2af2034..966db099a 100644
--- a/src/bcbench/evaluate/testgeneration.py
+++ b/src/bcbench/evaluate/testgeneration.py
@@ -1,4 +1,3 @@
-from collections.abc import Callable
 from pathlib import Path
 
 import yaml
@@ -6,7 +5,7 @@
 from bcbench.collection.patch_utils import extract_file_paths_from_patch
 from bcbench.config import get_config
 from bcbench.dataset import TestEntry, TestGenEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.exceptions import BuildError, NoTestsExtractedError, TestExecutionError
 from bcbench.github_actions import github_log_group
 from bcbench.logger import get_logger
@@ -78,7 +77,7 @@ def setup(self, context: EvaluationContext[TestGenEntry]) -> None:
         self._apply_input_postbuild(context.entry, context.repo_path)
         set_runtime_version(context.repo_path, context.entry.project_paths)
 
-    def run_agent(self, context: EvaluationContext[TestGenEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[TestGenEntry], agent_runner: AgentRunner[TestGenEntry]) -> None:
         with github_log_group(f"{context.agent_name} -- Entry: {context.entry.instance_id}"):
             context.metrics, context.experiment = agent_runner(context)
 
diff --git a/tests/test_evaluate_pipeline.py b/tests/test_evaluate_pipeline.py
index a1fc8324a..13ce7eeec 100644
--- a/tests/test_evaluate_pipeline.py
+++ b/tests/test_evaluate_pipeline.py
@@ -1,7 +1,6 @@
 """Tests for EvaluationPipeline.execute() template-method orchestration."""
 
 import json
-from collections.abc import Callable
 from pathlib import Path
 from unittest.mock import patch
 
@@ -10,7 +9,7 @@
 from bcbench.commands.evaluate import MockEvaluationPipeline
 from bcbench.config import get_config
 from bcbench.dataset import BaseDatasetEntry, BugFixEntry
-from bcbench.evaluate.base import EvaluationPipeline
+from bcbench.evaluate.base import AgentRunner, EvaluationPipeline
 from bcbench.exceptions import AgentTimeoutError
 from bcbench.results.base import BaseEvaluationResult
 from bcbench.types import AgentMetrics, EvaluationCategory, EvaluationContext, ExperimentConfiguration
@@ -31,7 +30,7 @@ def setup_workspace(self, entry: BugFixEntry, repo_path: Path) -> None:
     def setup(self, context: EvaluationContext[BugFixEntry]) -> None:
         self.setup_called = True
 
-    def run_agent(self, context: EvaluationContext[BugFixEntry], agent_runner: Callable) -> None:
+    def run_agent(self, context: EvaluationContext[BugFixEntry], agent_runner: AgentRunner[BugFixEntry]) -> None:
         self.run_agent_called = True
         if self.raise_in_run_agent is not None:
             raise self.raise_in_run_agent