Add REPL effect detection and input handling to pipeline runner

- Detect REPL effect in pipeline and enable interactive mode
- Enable raw terminal mode for REPL input capture
- Add keyboard input loop for REPL commands (return, up/down arrows, backspace)
- Process commands and handle pipeline mutations from REPL
- Fix lint issues in graph and REPL modules (type annotations, imports)

engine/effects/plugins/repl.py

@@ -30,7 +30,6 @@ Keyboard:
 """
 
 from dataclasses import dataclass, field
-from typing import Any, Optional
 
 from engine.effects.types import (
     EffectConfig,
@@ -69,7 +68,7 @@ class ReplEffect(EffectPlugin):
     def __init__(self):
         super().__init__()
         self.state = REPLState()
-        self._last_metrics: Optional[dict] = None
+        self._last_metrics: dict | None = None
 
     def process_partial(
         self, buf: list[str], ctx: EffectContext, partial: PartialUpdate
@@ -82,8 +81,6 @@ class ReplEffect(EffectPlugin):
 
     def process(self, buf: list[str], ctx: EffectContext) -> list[str]:
         """Render buffer with REPL overlay."""
-        result = list(buf)
-
         # Get display dimensions from context
         height = ctx.terminal_height if hasattr(ctx, "terminal_height") else len(buf)
         width = ctx.terminal_width if hasattr(ctx, "terminal_width") else 80
@@ -94,7 +91,6 @@ class ReplEffect(EffectPlugin):
 
         # Reserve space for REPL at bottom
         # HUD uses top 3 lines if enabled
-        hud_lines = 3 if show_hud else 0
         content_height = max(1, height - repl_height)
 
         # Build output
@@ -220,9 +216,7 @@ class ReplEffect(EffectPlugin):
 
         return {"fps": 0.0, "frame_time": 0.0}
 
-    def process_command(
-        self, command: str, ctx: Optional[EffectContext] = None
-    ) -> None:
+    def process_command(self, command: str, ctx: EffectContext | None = None) -> None:
         """Process a REPL command."""
         cmd = command.strip()
         if not cmd:
@@ -283,7 +277,7 @@ class ReplEffect(EffectPlugin):
         self.state.output_buffer.append("  clear - Clear output buffer")
         self.state.output_buffer.append("  quit - Show exit message")
 
-    def _cmd_status(self, ctx: Optional[EffectContext]):
+    def _cmd_status(self, ctx: EffectContext | None):
         """Show pipeline status."""
         if ctx:
             metrics = self._get_metrics(ctx)
@@ -299,7 +293,7 @@ class ReplEffect(EffectPlugin):
             f"History: {len(self.state.command_history)} commands"
         )
 
-    def _cmd_effects(self, ctx: Optional[EffectContext]):
+    def _cmd_effects(self, ctx: EffectContext | None):
         """List all effects."""
         if ctx:
             # Try to get effect list from context
@@ -313,7 +307,7 @@ class ReplEffect(EffectPlugin):
         else:
             self.state.output_buffer.append("No context available")
 
-    def _cmd_effect(self, args: list[str], ctx: Optional[EffectContext]):
+    def _cmd_effect(self, args: list[str], ctx: EffectContext | None):
         """Toggle effect on/off."""
         if len(args) < 2:
             self.state.output_buffer.append("Usage: effect <name> <on|off>")
@@ -336,7 +330,7 @@ class ReplEffect(EffectPlugin):
             "stage": effect_name,
         }
 
-    def _cmd_param(self, args: list[str], ctx: Optional[EffectContext]):
+    def _cmd_param(self, args: list[str], ctx: EffectContext | None):
         """Set effect parameter."""
         if len(args) < 3:
             self.state.output_buffer.append("Usage: param <effect> <param> <value>")
@@ -362,7 +356,7 @@ class ReplEffect(EffectPlugin):
             "delta": param_value,  # Note: This sets absolute value, need adjustment
         }
 
-    def _cmd_pipeline(self, ctx: Optional[EffectContext]):
+    def _cmd_pipeline(self, ctx: EffectContext | None):
         """Show current pipeline order."""
         if ctx:
             pipeline_order = ctx.get_state("pipeline_order")
@@ -375,7 +369,7 @@ class ReplEffect(EffectPlugin):
         else:
             self.state.output_buffer.append("No context available")
 
-    def get_pending_command(self) -> Optional[dict]:
+    def get_pending_command(self) -> dict | None:
         """Get and clear pending command for external handling."""
         cmd = getattr(self, "_pending_command", None)
         if cmd: