diff --git a/engine/config.py b/engine/config.py
index bf227ba..f7f86a3 100644
--- a/engine/config.py
+++ b/engine/config.py
@@ -129,7 +129,7 @@ class Config:
 
     script_fonts: dict[str, str] = field(default_factory=_get_platform_font_paths)
 
-    display: str = "terminal"
+    display: str = "pygame"
     websocket: bool = False
     websocket_port: int = 8765
 
@@ -237,7 +237,7 @@ GLITCH = "░▒▓█▌▐╌╍╎╏┃┆┇┊┋"
 KATA = "ﾊﾐﾋｰｳｼﾅﾓﾆｻﾜﾂｵﾘｱﾎﾃﾏｹﾒｴｶｷﾑﾕﾗｾﾈｽﾀﾇﾍ"
 
 # ─── WEBSOCKET ─────────────────────────────────────────────
-DISPLAY = _arg_value("--display", sys.argv) or "terminal"
+DISPLAY = _arg_value("--display", sys.argv) or "pygame"
 WEBSOCKET = "--websocket" in sys.argv
 WEBSOCKET_PORT = _arg_int("--websocket-port", 8765)
 
diff --git a/engine/pipeline/adapters.py b/engine/pipeline/adapters.py
index 6636760..35a0cab 100644
--- a/engine/pipeline/adapters.py
+++ b/engine/pipeline/adapters.py
@@ -183,7 +183,7 @@ class DisplayStage(Stage):
     def init(self, ctx: PipelineContext) -> bool:
         w = ctx.params.viewport_width if ctx.params else 80
         h = ctx.params.viewport_height if ctx.params else 24
-        result = self._display.init(w, h)
+        result = self._display.init(w, h, reuse=False)
         return result is not False
 
     def process(self, data: Any, ctx: PipelineContext) -> Any:
diff --git a/engine/pipeline/controller.py b/engine/pipeline/controller.py
index 11e39d1..b9bc92a 100644
--- a/engine/pipeline/controller.py
+++ b/engine/pipeline/controller.py
@@ -303,18 +303,14 @@ def create_pipeline_from_params(params: PipelineParams) -> Pipeline:
 
 def create_default_pipeline() -> Pipeline:
     """Create a default pipeline with all standard components."""
+    from engine.pipeline.adapters import DataSourceStage
+    from engine.sources_v2 import HeadlinesDataSource
+
     pipeline = Pipeline()
 
-    # Add source stage
-    source = StageRegistry.create("source", "headlines")
-    if source:
-        pipeline.add_stage("source", source)
-
-    # Add effect stages
-    for effect_name in ["noise", "fade", "glitch", "firehose", "hud"]:
-        effect = StageRegistry.create("effect", effect_name)
-        if effect:
-            pipeline.add_stage(f"effect_{effect_name}", effect)
+    # Add source stage (wrapped as Stage)
+    source = HeadlinesDataSource()
+    pipeline.add_stage("source", DataSourceStage(source, name="headlines"))
 
     # Add display stage
     display = StageRegistry.create("display", "terminal")
diff --git a/engine/pipeline/registry.py b/engine/pipeline/registry.py
index 4e0f969..e0b4423 100644
--- a/engine/pipeline/registry.py
+++ b/engine/pipeline/registry.py
@@ -28,7 +28,7 @@ class StageRegistry:
             cls._categories[category] = {}
 
         # Use class name as key
-        key = stage_class.__name__
+        key = getattr(stage_class, "__name__", stage_class.__class__.__name__)
         cls._categories[category][key] = stage_class
 
     @classmethod
@@ -90,6 +90,10 @@ def discover_stages() -> None:
         StageRegistry.register("source", HeadlinesDataSource)
         StageRegistry.register("source", PoetryDataSource)
         StageRegistry.register("source", PipelineDataSource)
+
+        StageRegistry._categories["source"]["headlines"] = HeadlinesDataSource
+        StageRegistry._categories["source"]["poetry"] = PoetryDataSource
+        StageRegistry._categories["source"]["pipeline"] = PipelineDataSource
     except ImportError:
         pass
 
@@ -98,14 +102,48 @@ def discover_stages() -> None:
     except ImportError:
         pass
 
-    try:
-        from engine.display import Display  # noqa: F401
-    except ImportError:
-        pass
+    # Register display stages
+    _register_display_stages()
 
     StageRegistry._discovered = True
 
 
+def _register_display_stages() -> None:
+    """Register display backends as stages."""
+    try:
+        from engine.display import DisplayRegistry
+    except ImportError:
+        return
+
+    DisplayRegistry.initialize()
+
+    for backend_name in DisplayRegistry.list_backends():
+        factory = _DisplayStageFactory(backend_name)
+        StageRegistry._categories.setdefault("display", {})[backend_name] = factory
+
+
+class _DisplayStageFactory:
+    """Factory that creates DisplayStage instances for a specific backend."""
+
+    def __init__(self, backend_name: str):
+        self._backend_name = backend_name
+
+    def __call__(self):
+        from engine.display import DisplayRegistry
+        from engine.pipeline.adapters import DisplayStage
+
+        display = DisplayRegistry.create(self._backend_name)
+        if display is None:
+            raise RuntimeError(
+                f"Failed to create display backend: {self._backend_name}"
+            )
+        return DisplayStage(display, name=self._backend_name)
+
+    @property
+    def __name__(self) -> str:
+        return self._backend_name.capitalize() + "Stage"
+
+
 # Convenience functions
 def register_source(stage_class: type[Stage]) -> None:
     """Register a source stage."""
diff --git a/engine/sources_v2.py b/engine/sources_v2.py
index 9a3aa67..9fc7652 100644
--- a/engine/sources_v2.py
+++ b/engine/sources_v2.py
@@ -9,6 +9,7 @@ Each data source implements a common interface:
 """
 
 from abc import ABC, abstractmethod
+from collections.abc import Callable
 from dataclasses import dataclass
 from typing import Any
 
@@ -125,6 +126,115 @@ class PipelineDataSource(DataSource):
         return self.fetch()
 
 
+class MetricsDataSource(DataSource):
+    """Data source that renders live pipeline metrics as ASCII art.
+
+    Wraps a Pipeline and displays active stages with their average execution
+    time and approximate FPS impact. Updates lazily when camera is about to
+    focus on a new node (frame % 15 == 12).
+    """
+
+    def __init__(
+        self,
+        pipeline: Any,
+        viewport_width: int = 80,
+        viewport_height: int = 24,
+    ):
+        self.pipeline = pipeline
+        self.viewport_width = viewport_width
+        self.viewport_height = viewport_height
+        self.frame = 0
+        self._cached_metrics: dict | None = None
+
+    @property
+    def name(self) -> str:
+        return "metrics"
+
+    @property
+    def is_dynamic(self) -> bool:
+        return True
+
+    def fetch(self) -> list[SourceItem]:
+        if self.frame % 15 == 12:
+            self._cached_metrics = None
+
+        if self._cached_metrics is None:
+            self._cached_metrics = self._fetch_metrics()
+
+        buffer = self._render_metrics(self._cached_metrics)
+        self.frame += 1
+        content = "\n".join(buffer)
+        return [
+            SourceItem(content=content, source="metrics", timestamp=f"f{self.frame}")
+        ]
+
+    def _fetch_metrics(self) -> dict:
+        if hasattr(self.pipeline, "get_metrics_summary"):
+            metrics = self.pipeline.get_metrics_summary()
+            if "error" not in metrics:
+                return metrics
+        return {"stages": {}, "pipeline": {"avg_ms": 0}}
+
+    def _render_metrics(self, metrics: dict) -> list[str]:
+        stages = metrics.get("stages", {})
+
+        if not stages:
+            return self._render_empty()
+
+        active_stages = {
+            name: stats for name, stats in stages.items() if stats.get("avg_ms", 0) > 0
+        }
+
+        if not active_stages:
+            return self._render_empty()
+
+        total_avg = sum(s["avg_ms"] for s in active_stages.values())
+        if total_avg == 0:
+            total_avg = 1
+
+        lines: list[str] = []
+        lines.append("═" * self.viewport_width)
+        lines.append(" PIPELINE METRICS ".center(self.viewport_width, "─"))
+        lines.append("─" * self.viewport_width)
+
+        header = f"{'STAGE':<20} {'AVG_MS':>8} {'FPS %':>8}"
+        lines.append(header)
+        lines.append("─" * self.viewport_width)
+
+        for name, stats in sorted(active_stages.items()):
+            avg_ms = stats.get("avg_ms", 0)
+            fps_impact = (avg_ms / 16.67) * 100 if avg_ms > 0 else 0
+
+            row = f"{name:<20} {avg_ms:>7.2f} {fps_impact:>7.1f}%"
+            lines.append(row[: self.viewport_width])
+
+        lines.append("─" * self.viewport_width)
+        total_row = (
+            f"{'TOTAL':<20} {total_avg:>7.2f} {(total_avg / 16.67) * 100:>7.1f}%"
+        )
+        lines.append(total_row[: self.viewport_width])
+        lines.append("─" * self.viewport_width)
+        lines.append(
+            f" Frame:{self.frame:04d}  Cache:{'HIT' if self._cached_metrics else 'MISS'}"
+        )
+
+        while len(lines) < self.viewport_height:
+            lines.append(" " * self.viewport_width)
+
+        return lines[: self.viewport_height]
+
+    def _render_empty(self) -> list[str]:
+        lines = [" " * self.viewport_width for _ in range(self.viewport_height)]
+        msg = "No metrics available"
+        y = self.viewport_height // 2
+        x = (self.viewport_width - len(msg)) // 2
+        lines[y] = " " * x + msg + " " * (self.viewport_width - x - len(msg))
+        return lines
+
+    def get_items(self) -> list[SourceItem]:
+        return self.fetch()
+
+
 class CachedDataSource(DataSource):
     """Data source that wraps another source with caching."""
 
@@ -146,6 +256,44 @@ class CachedDataSource(DataSource):
         return self._items
 
 
+class TransformDataSource(DataSource):
+    """Data source that transforms items from another source.
+
+    Applies optional filter and map functions to each item.
+    This enables chaining: source → transform → transformed output.
+
+    Args:
+        source: The source to fetch items from
+        filter_fn: Optional function(item: SourceItem) -> bool
+        map_fn: Optional function(item: SourceItem) -> SourceItem
+    """
+
+    def __init__(
+        self,
+        source: DataSource,
+        filter_fn: Callable[[SourceItem], bool] | None = None,
+        map_fn: Callable[[SourceItem], SourceItem] | None = None,
+    ):
+        self.source = source
+        self.filter_fn = filter_fn
+        self.map_fn = map_fn
+
+    @property
+    def name(self) -> str:
+        return f"transform:{self.source.name}"
+
+    def fetch(self) -> list[SourceItem]:
+        items = self.source.fetch()
+
+        if self.filter_fn:
+            items = [item for item in items if self.filter_fn(item)]
+
+        if self.map_fn:
+            items = [self.map_fn(item) for item in items]
+
+        return items
+
+
 class CompositeDataSource(DataSource):
     """Data source that combines multiple sources."""
 
diff --git a/mise.toml b/mise.toml
index 17ebbdb..c4e89a6 100644
--- a/mise.toml
+++ b/mise.toml
@@ -38,19 +38,16 @@ run-kitty = { run = "uv run mainline.py --display kitty", depends = ["sync-all"]
 run-pygame = { run = "uv run mainline.py --display pygame", depends = ["sync-all"] }
 run-both = { run = "uv run mainline.py --display both", depends = ["sync-all"] }
 run-client = { run = "mise run run-both & sleep 2 && $(open http://localhost:8766 2>/dev/null || xdg-open http://localhost:8766 2>/dev/null || echo 'Open http://localhost:8766 manually'); wait", depends = ["sync-all"] }
-run-demo = { run = "uv run mainline.py --demo --display pygame", depends = ["sync-all"] }
-run-pipeline = "uv run mainline.py --pipeline-diagram"
-run-pipeline-demo = { run = "uv run mainline.py --pipeline-demo --display pygame", depends = ["sync-all"] }
 
 # =====================
-# New Pipeline Architecture (unified Stage-based)
+# Pipeline Architecture (unified Stage-based)
 # =====================
 
-run-v2 = { run = "uv run mainline.py --pipeline --display pygame", depends = ["sync-all"] }
-run-v2-demo = { run = "uv run mainline.py --pipeline --pipeline-preset demo --display pygame", depends = ["sync-all"] }
-run-v2-poetry = { run = "uv run mainline.py --pipeline --pipeline-preset poetry --display pygame", depends = ["sync-all"] }
-run-v2-websocket = { run = "uv run mainline.py --pipeline --pipeline-preset websocket", depends = ["sync-all"] }
-run-v2-firehose = { run = "uv run mainline.py --pipeline --pipeline-preset firehose --display pygame", depends = ["sync-all"] }
+run-pipeline = { run = "uv run mainline.py --pipeline --display pygame", depends = ["sync-all"] }
+run-pipeline-demo = { run = "uv run mainline.py --pipeline --pipeline-preset demo --display pygame", depends = ["sync-all"] }
+run-pipeline-poetry = { run = "uv run mainline.py --pipeline --pipeline-preset poetry --display pygame", depends = ["sync-all"] }
+run-pipeline-websocket = { run = "uv run mainline.py --pipeline --pipeline-preset websocket", depends = ["sync-all"] }
+run-pipeline-firehose = { run = "uv run mainline.py --pipeline --pipeline-preset firehose --display pygame", depends = ["sync-all"] }
 
 # =====================
 # Presets (Animation-controlled modes)
diff --git a/tests/test_pipeline.py b/tests/test_pipeline.py
new file mode 100644
index 0000000..aab2099
--- /dev/null
+++ b/tests/test_pipeline.py
@@ -0,0 +1,281 @@
+"""
+Tests for the new unified pipeline architecture.
+"""
+
+from unittest.mock import MagicMock
+
+from engine.pipeline import (
+    Pipeline,
+    PipelineConfig,
+    PipelineContext,
+    Stage,
+    StageRegistry,
+    create_default_pipeline,
+    discover_stages,
+)
+
+
+class TestStageRegistry:
+    """Tests for StageRegistry."""
+
+    def setup_method(self):
+        """Reset registry before each test."""
+        StageRegistry._discovered = False
+        StageRegistry._categories.clear()
+        StageRegistry._instances.clear()
+
+    def test_discover_stages_registers_sources(self):
+        """discover_stages registers source stages."""
+        discover_stages()
+
+        sources = StageRegistry.list("source")
+        assert "HeadlinesDataSource" in sources
+        assert "PoetryDataSource" in sources
+        assert "PipelineDataSource" in sources
+
+    def test_discover_stages_registers_displays(self):
+        """discover_stages registers display stages."""
+        discover_stages()
+
+        displays = StageRegistry.list("display")
+        assert "terminal" in displays
+        assert "pygame" in displays
+        assert "websocket" in displays
+        assert "null" in displays
+        assert "sixel" in displays
+
+    def test_create_source_stage(self):
+        """StageRegistry.create creates source stages."""
+        discover_stages()
+
+        source = StageRegistry.create("source", "HeadlinesDataSource")
+        assert source is not None
+        assert source.name == "headlines"
+
+    def test_create_display_stage(self):
+        """StageRegistry.create creates display stages."""
+        discover_stages()
+
+        display = StageRegistry.create("display", "terminal")
+        assert display is not None
+        assert hasattr(display, "_display")
+
+    def test_create_display_stage_pygame(self):
+        """StageRegistry.create creates pygame display stage."""
+        discover_stages()
+
+        display = StageRegistry.create("display", "pygame")
+        assert display is not None
+
+
+class TestPipeline:
+    """Tests for Pipeline class."""
+
+    def setup_method(self):
+        """Reset registry before each test."""
+        StageRegistry._discovered = False
+        StageRegistry._categories.clear()
+        StageRegistry._instances.clear()
+        discover_stages()
+
+    def test_create_pipeline(self):
+        """Pipeline can be created with config."""
+        config = PipelineConfig(source="headlines", display="terminal")
+        pipeline = Pipeline(config=config)
+
+        assert pipeline.config is not None
+        assert pipeline.config.source == "headlines"
+        assert pipeline.config.display == "terminal"
+
+    def test_add_stage(self):
+        """Pipeline.add_stage adds a stage."""
+        pipeline = Pipeline()
+        mock_stage = MagicMock(spec=Stage)
+        mock_stage.name = "test_stage"
+        mock_stage.category = "test"
+
+        pipeline.add_stage("test", mock_stage)
+
+        assert "test" in pipeline.stages
+
+    def test_build_resolves_dependencies(self):
+        """Pipeline.build resolves execution order."""
+        pipeline = Pipeline()
+        mock_source = MagicMock(spec=Stage)
+        mock_source.name = "source"
+        mock_source.category = "source"
+        mock_source.dependencies = set()
+
+        mock_display = MagicMock(spec=Stage)
+        mock_display.name = "display"
+        mock_display.category = "display"
+        mock_display.dependencies = {"source"}
+
+        pipeline.add_stage("source", mock_source)
+        pipeline.add_stage("display", mock_display)
+        pipeline.build()
+
+        assert pipeline._initialized is True
+        assert "source" in pipeline.execution_order
+        assert "display" in pipeline.execution_order
+
+    def test_execute_runs_stages(self):
+        """Pipeline.execute runs all stages in order."""
+        pipeline = Pipeline()
+
+        call_order = []
+
+        mock_source = MagicMock(spec=Stage)
+        mock_source.name = "source"
+        mock_source.category = "source"
+        mock_source.dependencies = set()
+        mock_source.process = lambda data, ctx: call_order.append("source") or "data"
+
+        mock_effect = MagicMock(spec=Stage)
+        mock_effect.name = "effect"
+        mock_effect.category = "effect"
+        mock_effect.dependencies = {"source"}
+        mock_effect.process = lambda data, ctx: call_order.append("effect") or data
+
+        mock_display = MagicMock(spec=Stage)
+        mock_display.name = "display"
+        mock_display.category = "display"
+        mock_display.dependencies = {"effect"}
+        mock_display.process = lambda data, ctx: call_order.append("display") or data
+
+        pipeline.add_stage("source", mock_source)
+        pipeline.add_stage("effect", mock_effect)
+        pipeline.add_stage("display", mock_display)
+        pipeline.build()
+
+        result = pipeline.execute(None)
+
+        assert result.success is True
+        assert call_order == ["source", "effect", "display"]
+
+    def test_execute_handles_stage_failure(self):
+        """Pipeline.execute handles stage failures."""
+        pipeline = Pipeline()
+
+        mock_source = MagicMock(spec=Stage)
+        mock_source.name = "source"
+        mock_source.category = "source"
+        mock_source.dependencies = set()
+        mock_source.process = lambda data, ctx: "data"
+
+        mock_failing = MagicMock(spec=Stage)
+        mock_failing.name = "failing"
+        mock_failing.category = "effect"
+        mock_failing.dependencies = {"source"}
+        mock_failing.optional = False
+        mock_failing.process = lambda data, ctx: (_ for _ in ()).throw(
+            Exception("fail")
+        )
+
+        pipeline.add_stage("source", mock_source)
+        pipeline.add_stage("failing", mock_failing)
+        pipeline.build()
+
+        result = pipeline.execute(None)
+
+        assert result.success is False
+        assert result.error is not None
+
+    def test_optional_stage_failure_continues(self):
+        """Pipeline.execute continues on optional stage failure."""
+        pipeline = Pipeline()
+
+        mock_source = MagicMock(spec=Stage)
+        mock_source.name = "source"
+        mock_source.category = "source"
+        mock_source.dependencies = set()
+        mock_source.process = lambda data, ctx: "data"
+
+        mock_optional = MagicMock(spec=Stage)
+        mock_optional.name = "optional"
+        mock_optional.category = "effect"
+        mock_optional.dependencies = {"source"}
+        mock_optional.optional = True
+        mock_optional.process = lambda data, ctx: (_ for _ in ()).throw(
+            Exception("fail")
+        )
+
+        pipeline.add_stage("source", mock_source)
+        pipeline.add_stage("optional", mock_optional)
+        pipeline.build()
+
+        result = pipeline.execute(None)
+
+        assert result.success is True
+
+
+class TestPipelineContext:
+    """Tests for PipelineContext."""
+
+    def test_init_empty(self):
+        """PipelineContext initializes with empty services and state."""
+        ctx = PipelineContext()
+
+        assert ctx.services == {}
+        assert ctx.state == {}
+
+    def test_init_with_services(self):
+        """PipelineContext accepts initial services."""
+        ctx = PipelineContext(services={"display": MagicMock()})
+
+        assert "display" in ctx.services
+
+    def test_init_with_state(self):
+        """PipelineContext accepts initial state."""
+        ctx = PipelineContext(initial_state={"count": 42})
+
+        assert ctx.get_state("count") == 42
+
+    def test_get_set_services(self):
+        """PipelineContext can get/set services."""
+        ctx = PipelineContext()
+        mock_service = MagicMock()
+
+        ctx.set("test_service", mock_service)
+
+        assert ctx.get("test_service") == mock_service
+
+    def test_get_set_state(self):
+        """PipelineContext can get/set state."""
+        ctx = PipelineContext()
+
+        ctx.set_state("counter", 100)
+
+        assert ctx.get_state("counter") == 100
+
+    def test_lazy_resolver(self):
+        """PipelineContext resolves lazy services."""
+        ctx = PipelineContext()
+
+        config = ctx.get("config")
+        assert config is not None
+
+    def test_has_capability(self):
+        """PipelineContext.has_capability checks for services."""
+        ctx = PipelineContext(services={"display.output": MagicMock()})
+
+        assert ctx.has_capability("display.output") is True
+        assert ctx.has_capability("missing") is False
+
+
+class TestCreateDefaultPipeline:
+    """Tests for create_default_pipeline function."""
+
+    def setup_method(self):
+        """Reset registry before each test."""
+        StageRegistry._discovered = False
+        StageRegistry._categories.clear()
+        StageRegistry._instances.clear()
+        discover_stages()
+
+    def test_create_default_pipeline(self):
+        """create_default_pipeline creates a working pipeline."""
+        pipeline = create_default_pipeline()
+
+        assert pipeline is not None
+        assert "display" in pipeline.stages