diff --git a/src/felix_agent_sdk/_version.py b/src/felix_agent_sdk/_version.py
index d3ec452..3ced358 100644
--- a/src/felix_agent_sdk/_version.py
+++ b/src/felix_agent_sdk/_version.py
@@ -1 +1 @@
-__version__ = "0.2.0"
+__version__ = "0.2.1"
diff --git a/src/felix_agent_sdk/visualization/helix_visualizer.py b/src/felix_agent_sdk/visualization/helix_visualizer.py
index 6ed7963..c45f13c 100644
--- a/src/felix_agent_sdk/visualization/helix_visualizer.py
+++ b/src/felix_agent_sdk/visualization/helix_visualizer.py
@@ -286,8 +286,21 @@ def render(
             day: Current simulation day for the header.
             extra_info: Arbitrary key-value pairs shown in the header.
         """
-        sys.stdout.write(clear_screen())
-        sys.stdout.write(self.render_to_string(tick=tick, day=day, extra_info=extra_info))
+        # Ensure stdout can handle Unicode block-drawing characters on Windows
+        # where the default encoding is cp1252.
+        if hasattr(sys.stdout, "reconfigure"):
+            try:
+                sys.stdout.reconfigure(encoding="utf-8")
+            except (AttributeError, OSError):
+                pass  # already reconfigured, unsupported, or redirected stream
+
+        output = clear_screen() + self.render_to_string(
+            tick=tick, day=day, extra_info=extra_info
+        )
+        try:
+            sys.stdout.write(output)
+        except UnicodeEncodeError:
+            sys.stdout.buffer.write(output.encode("utf-8"))
         sys.stdout.flush()
 
     def render_to_string(
diff --git a/tests/conftest.py b/tests/conftest.py
index 1aaac09..4de71c3 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -17,7 +17,6 @@
     CompletionResult,
     MessageRole,
     ProviderConfig,
-    StreamChunk,
 )
 
 
diff --git a/tests/integration/test_providers.py b/tests/integration/test_providers.py
index 1e8f4f9..96bf7db 100644
--- a/tests/integration/test_providers.py
+++ b/tests/integration/test_providers.py
@@ -20,7 +20,7 @@
 
 import pytest
 
-from felix_agent_sdk.providers.types import ChatMessage, CompletionResult, MessageRole, StreamChunk
+from felix_agent_sdk.providers.types import ChatMessage, CompletionResult, MessageRole
 
 # ---------------------------------------------------------------------------
 # Skip conditions
diff --git a/tests/integration/test_workflow_pipeline.py b/tests/integration/test_workflow_pipeline.py
index 5919e00..5b9acf3 100644
--- a/tests/integration/test_workflow_pipeline.py
+++ b/tests/integration/test_workflow_pipeline.py
@@ -9,7 +9,6 @@
 
 from unittest.mock import MagicMock
 
-import pytest
 
 from felix_agent_sdk.providers.base import BaseProvider
 from felix_agent_sdk.providers.types import CompletionResult
@@ -157,7 +156,7 @@ def test_hub_shutdown(self):
         )
         workflow = FelixWorkflow(config, provider)
 
-        result = workflow.run("Test cleanup")
+        workflow.run("Test cleanup")
 
         # If cleanup failed we'd get errors on subsequent runs
         result2 = workflow.run("Second run")
diff --git a/tests/unit/test_anthropic_provider.py b/tests/unit/test_anthropic_provider.py
index dd76ef3..6fa5528 100644
--- a/tests/unit/test_anthropic_provider.py
+++ b/tests/unit/test_anthropic_provider.py
@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-from contextlib import contextmanager
-from typing import Any
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -20,7 +18,6 @@
     ChatMessage,
     CompletionResult,
     MessageRole,
-    StreamChunk,
 )
 
 
diff --git a/tests/unit/test_central_post.py b/tests/unit/test_central_post.py
index 618f3bc..6a3caf2 100644
--- a/tests/unit/test_central_post.py
+++ b/tests/unit/test_central_post.py
@@ -398,7 +398,8 @@ def test_multiple_callbacks_for_same_event(self, central_post):
 
     def test_remove_lifecycle_callback(self, central_post):
         log = []
-        cb = lambda aid: log.append(aid)
+        def cb(aid):
+            return log.append(aid)
         central_post.add_lifecycle_callback(AgentLifecycleEvent.FAILED, cb)
         central_post.remove_lifecycle_callback(AgentLifecycleEvent.FAILED, cb)
         central_post.emit_lifecycle_event(AgentLifecycleEvent.FAILED, "agent-1")
diff --git a/tests/unit/test_cli.py b/tests/unit/test_cli.py
index ee639a1..fb88f02 100644
--- a/tests/unit/test_cli.py
+++ b/tests/unit/test_cli.py
@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-import os
-import tempfile
 from pathlib import Path
 
 import pytest
diff --git a/tests/unit/test_compression.py b/tests/unit/test_compression.py
index 77df80e..e348d8a 100644
--- a/tests/unit/test_compression.py
+++ b/tests/unit/test_compression.py
@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import json
 
 import pytest
 
diff --git a/tests/unit/test_context_builder.py b/tests/unit/test_context_builder.py
index 6316273..8975c4b 100644
--- a/tests/unit/test_context_builder.py
+++ b/tests/unit/test_context_builder.py
@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import pytest
 
 from felix_agent_sdk.workflows.context_builder import (
     CollaborativeContextBuilder,
diff --git a/tests/unit/test_dynamic_spawner.py b/tests/unit/test_dynamic_spawner.py
index f1d58dc..6198593 100644
--- a/tests/unit/test_dynamic_spawner.py
+++ b/tests/unit/test_dynamic_spawner.py
@@ -9,7 +9,7 @@
 from felix_agent_sdk.communication.central_post import CentralPost
 from felix_agent_sdk.communication.spoke import SpokeManager
 from felix_agent_sdk.core.helix import HelixConfig
-from felix_agent_sdk.events import EventBus, EventType
+from felix_agent_sdk.events import EventBus
 from felix_agent_sdk.providers.base import BaseProvider
 from felix_agent_sdk.providers.types import CompletionResult
 from felix_agent_sdk.spawning import ConfidenceMonitor, DynamicSpawner
diff --git a/tests/unit/test_events.py b/tests/unit/test_events.py
index 6d5a719..496062c 100644
--- a/tests/unit/test_events.py
+++ b/tests/unit/test_events.py
@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 import threading
-import time
 
 import pytest
 
diff --git a/tests/unit/test_helix_visualizer.py b/tests/unit/test_helix_visualizer.py
index fa742eb..d5939bf 100644
--- a/tests/unit/test_helix_visualizer.py
+++ b/tests/unit/test_helix_visualizer.py
@@ -317,3 +317,39 @@ def test_footer_without_monitor(self, viz):
         assert "Confidence" in output
         # Should not crash without monitor
         assert "Trend" not in output
+
+
+# ------------------------------------------------------------------
+# Windows encoding fallback
+# ------------------------------------------------------------------
+
+
+class TestRenderEncodingFallback:
+    def test_render_survives_unicode_encode_error(self, viz, monkeypatch):
+        """render() should not crash when stdout can't handle Unicode."""
+        import io
+
+        viz.register_agent("a1", "Agent1", color="cyan")
+        viz.update("a1", 0.5, 0.8)
+
+        # Simulate a stdout that raises UnicodeEncodeError on write
+        class FakeStdout:
+            def write(self, s):
+                raise UnicodeEncodeError("cp1252", s, 0, 1, "bad char")
+
+            def flush(self):
+                ...  # intentionally empty — test double
+
+            buffer = io.BytesIO()
+
+            def reconfigure(self, **kwargs):
+                ...  # intentionally empty — simulates already-reconfigured
+
+        fake = FakeStdout()
+        monkeypatch.setattr("sys.stdout", fake)
+
+        # Should not raise — falls back to buffer.write(utf-8)
+        viz.render()
+
+        # Verify something was written to the buffer
+        assert fake.buffer.tell() > 0
diff --git a/tests/unit/test_knowledge_store.py b/tests/unit/test_knowledge_store.py
index 0788eb3..f592516 100644
--- a/tests/unit/test_knowledge_store.py
+++ b/tests/unit/test_knowledge_store.py
@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import time
 
 import pytest
 
@@ -10,7 +9,6 @@
     ConfidenceLevel,
     KnowledgeEntry,
     KnowledgeQuery,
-    KnowledgeStore,
     KnowledgeType,
 )
 
diff --git a/tests/unit/test_llm_agent_streaming.py b/tests/unit/test_llm_agent_streaming.py
index fa516fe..96951d9 100644
--- a/tests/unit/test_llm_agent_streaming.py
+++ b/tests/unit/test_llm_agent_streaming.py
@@ -6,7 +6,7 @@
 
 from felix_agent_sdk.agents.llm_agent import LLMAgent, LLMTask
 from felix_agent_sdk.core.helix import HelixConfig, HelixGeometry
-from felix_agent_sdk.events import EventBus, EventType
+from felix_agent_sdk.events import EventBus
 from felix_agent_sdk.providers.base import BaseProvider
 from felix_agent_sdk.providers.types import CompletionResult, StreamChunk
 from felix_agent_sdk.streaming import CallbackStreamHandler, StreamHandler
diff --git a/tests/unit/test_local_provider.py b/tests/unit/test_local_provider.py
index 46937c5..c33e05f 100644
--- a/tests/unit/test_local_provider.py
+++ b/tests/unit/test_local_provider.py
@@ -4,7 +4,6 @@
 
 from unittest.mock import MagicMock, patch
 
-import pytest
 
 from felix_agent_sdk.providers.local import LocalProvider
 from felix_agent_sdk.providers.openai_provider import OpenAIProvider
diff --git a/tests/unit/test_logging.py b/tests/unit/test_logging.py
index 1ac70f8..b3642bc 100644
--- a/tests/unit/test_logging.py
+++ b/tests/unit/test_logging.py
@@ -5,7 +5,6 @@
 import json
 import logging
 
-import pytest
 
 from felix_agent_sdk.events import EventBus, EventType, FelixEvent
 from felix_agent_sdk.utils.logging import (
@@ -25,7 +24,6 @@ def _capture_handler() -> logging.Handler:
     """Return a handler that stores formatted records in handler.records."""
     handler = logging.StreamHandler()
     handler.records: list[str] = []  # type: ignore[attr-defined]
-    original_emit = handler.emit
 
     def capturing_emit(record: logging.LogRecord) -> None:
         handler.records.append(handler.format(record))  # type: ignore[attr-defined]
@@ -169,7 +167,7 @@ def test_logs_events(self):
         configure_logging(FelixLogConfig(level="DEBUG", output_handler=handler))
 
         bus = EventBus()
-        bridge = EventLogBridge(bus)
+        EventLogBridge(bus)
 
         bus.emit(FelixEvent(
             event_type=EventType.WORKFLOW_STARTED,
@@ -184,7 +182,7 @@ def test_json_bridge(self):
         configure_logging(FelixLogConfig(level="DEBUG", format="json", output_handler=handler))
 
         bus = EventBus()
-        bridge = EventLogBridge(bus)
+        EventLogBridge(bus)
 
         bus.emit(FelixEvent(
             event_type=EventType.TASK_COMPLETED,
@@ -215,7 +213,7 @@ def test_custom_level_map(self):
         configure_logging(FelixLogConfig(level="DEBUG", output_handler=handler))
 
         bus = EventBus()
-        bridge = EventLogBridge(bus, level_map={"custom.event": "WARNING"})
+        EventLogBridge(bus, level_map={"custom.event": "WARNING"})
 
         bus.emit(FelixEvent(event_type="custom.event", source="test"))
 
@@ -226,7 +224,7 @@ def test_default_level_is_debug(self):
         configure_logging(FelixLogConfig(level="DEBUG", output_handler=handler))
 
         bus = EventBus()
-        bridge = EventLogBridge(bus)
+        EventLogBridge(bus)
 
         bus.emit(FelixEvent(event_type="unknown.event.type", source="test"))
 
@@ -237,7 +235,7 @@ def test_workflow_events_log_at_info(self):
         configure_logging(FelixLogConfig(level="DEBUG", output_handler=handler))
 
         bus = EventBus()
-        bridge = EventLogBridge(bus)
+        EventLogBridge(bus)
 
         bus.emit(FelixEvent(event_type=EventType.WORKFLOW_STARTED, source="wf"))
         bus.emit(FelixEvent(event_type=EventType.WORKFLOW_COMPLETED, source="wf"))
diff --git a/tests/unit/test_messages.py b/tests/unit/test_messages.py
index 13636a0..a96d7ab 100644
--- a/tests/unit/test_messages.py
+++ b/tests/unit/test_messages.py
@@ -5,7 +5,6 @@
 import time
 import uuid
 
-import pytest
 
 from felix_agent_sdk.communication.messages import Message, MessageType
 
diff --git a/tests/unit/test_openai_provider.py b/tests/unit/test_openai_provider.py
index dc74fc3..2bdb47c 100644
--- a/tests/unit/test_openai_provider.py
+++ b/tests/unit/test_openai_provider.py
@@ -18,7 +18,6 @@
     ChatMessage,
     CompletionResult,
     MessageRole,
-    StreamChunk,
 )
 
 
diff --git a/tests/unit/test_registry.py b/tests/unit/test_registry.py
index ba761cd..1cd4af5 100644
--- a/tests/unit/test_registry.py
+++ b/tests/unit/test_registry.py
@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from unittest.mock import MagicMock, patch
+from unittest.mock import patch
 
 import pytest
 
diff --git a/tests/unit/test_spoke.py b/tests/unit/test_spoke.py
index cb709a0..277f06f 100644
--- a/tests/unit/test_spoke.py
+++ b/tests/unit/test_spoke.py
@@ -4,7 +4,6 @@
 
 from unittest.mock import MagicMock
 
-import pytest
 
 from felix_agent_sdk.communication.central_post import CentralPost
 from felix_agent_sdk.communication.messages import Message, MessageType
@@ -384,7 +383,7 @@ def test_broadcast_excludes_specified_ids(self, central_post, spoke_manager):
         assert len(confirmations) == 2
 
     def test_broadcast_skips_disconnected_spokes(self, central_post, spoke_manager):
-        spoke1 = spoke_manager.create_spoke("agent-1")
+        spoke_manager.create_spoke("agent-1")
         spoke2 = spoke_manager.create_spoke("agent-2")
         spoke2.disconnect()
         confirmations = spoke_manager.broadcast_message(
diff --git a/tests/unit/test_streaming.py b/tests/unit/test_streaming.py
index 0224532..621a22c 100644
--- a/tests/unit/test_streaming.py
+++ b/tests/unit/test_streaming.py
@@ -4,7 +4,7 @@
 
 import pytest
 
-from felix_agent_sdk.events import EventBus, EventType
+from felix_agent_sdk.events import EventBus
 from felix_agent_sdk.providers.types import StreamChunk
 from felix_agent_sdk.streaming import (
     CallbackStreamHandler,
diff --git a/tests/unit/test_synthesizer.py b/tests/unit/test_synthesizer.py
index 01179d9..c68ed55 100644
--- a/tests/unit/test_synthesizer.py
+++ b/tests/unit/test_synthesizer.py
@@ -4,7 +4,6 @@
 
 from unittest.mock import MagicMock
 
-import pytest
 
 from felix_agent_sdk.agents.llm_agent import LLMResult
 from felix_agent_sdk.providers.base import BaseProvider
@@ -108,7 +107,7 @@ def test_without_compression(self):
         synth = WorkflowSynthesizer(provider, config)
 
         results = [_make_result("a1", "Data", 0.5)]
-        output = synth.synthesize(results, "task")
+        synth.synthesize(results, "task")
         assert provider.complete.called
 
 
diff --git a/tests/unit/test_task_memory.py b/tests/unit/test_task_memory.py
index 78a8f6e..b9cb66c 100644
--- a/tests/unit/test_task_memory.py
+++ b/tests/unit/test_task_memory.py
@@ -2,12 +2,10 @@
 
 from __future__ import annotations
 
-import pytest
 
 from felix_agent_sdk.memory.task_memory import (
     TaskComplexity,
     TaskExecution,
-    TaskMemory,
     TaskMemoryQuery,
     TaskOutcome,
     TaskPattern,
diff --git a/tests/unit/test_workflow_config.py b/tests/unit/test_workflow_config.py
index 2bbee1f..eca4529 100644
--- a/tests/unit/test_workflow_config.py
+++ b/tests/unit/test_workflow_config.py
@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import pytest
 
 from felix_agent_sdk.core.helix import HelixConfig
 from felix_agent_sdk.workflows.config import (