Make JAX the primary fused-pipeline path for CPU/GPU parity

JAX via XLA produces identical output on CPU and GPU. Previously
CUDA hand-written kernels were preferred on GPU, causing visual
differences vs the JAX CPU fallback. Now JAX is always used first,
with legacy CuPy/GPUFrame as fallback only when JAX is unavailable.

Also adds comprehensive CLAUDE.md for the monorepo.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

l1/sexp_effects/primitive_libs/streaming_gpu.py

@@ -979,51 +979,52 @@ def prim_fused_pipeline(img, effects_list, **dynamic_params):
     # Update effects list to exclude resize ops
     effects_list = other_effects
 
-    if not _FUSED_KERNELS_AVAILABLE:
-        if _FUSED_JAX_AVAILABLE:
-            # JAX path: convert to JAX array, apply effects, convert back to numpy
-            if _FUSED_CALL_COUNT <= 3:
-                print(f"[FUSED JAX] Using JAX path for {len(effects_list)} effects", file=sys.stderr)
-            # Extract numpy array from GPUFrame if needed
-            if isinstance(img, GPUFrame):
-                arr = img.cpu if not img.is_on_gpu else img.gpu.get()
-            elif hasattr(img, 'get'):
-                arr = img.get()  # CuPy to numpy
+    # JAX is the primary path — same code on CPU and GPU, XLA handles dispatch
+    if _FUSED_JAX_AVAILABLE:
+        if _FUSED_CALL_COUNT <= 3:
+            print(f"[FUSED JAX] Using JAX path for {len(effects_list)} effects", file=sys.stderr)
+        # Extract numpy array from GPUFrame if needed
+        if isinstance(img, GPUFrame):
+            arr = img.cpu if not img.is_on_gpu else img.gpu.get()
+        elif hasattr(img, 'get'):
+            arr = img.get()  # CuPy to numpy
+        else:
+            arr = np.asarray(img)
+        result = jnp.array(arr)
+        for effect in effects_list:
+            op = effect['op']
+            if op == 'rotate':
+                angle = dynamic_params.get('rotate_angle', effect.get('angle', 0))
+                result = _jax_fused_fns['rotate'](result, angle=angle)
+            elif op == 'zoom':
+                amount = dynamic_params.get('zoom_amount', effect.get('amount', 1.0))
+                result = _jax_fused_fns['zoom'](result, amount=amount)
+            elif op == 'hue_shift':
+                degrees = effect.get('degrees', 0)
+                if abs(degrees) > 0.1:
+                    result = _jax_fused_fns['hue_shift'](result, degrees=degrees)
+            elif op == 'ripple':
+                amplitude = dynamic_params.get('ripple_amplitude', effect.get('amplitude', 10))
+                if amplitude > 0.1:
+                    result = _jax_fused_fns['ripple'](result,
+                        amplitude=amplitude,
+                        frequency=effect.get('frequency', 8),
+                        decay=effect.get('decay', 2),
+                        phase=dynamic_params.get('ripple_phase', effect.get('phase', 0)),
+                        cx=effect.get('center_x'),
+                        cy=effect.get('center_y'))
+            elif op == 'brightness':
+                factor = effect.get('factor', 1.0)
+                result = _jax_fused_fns['brightness'](result, factor=factor)
+            elif op == 'invert':
+                amount = effect.get('amount', 0)
+                if amount > 0.5:
+                    result = _jax_fused_fns['invert'](result)
             else:
-                arr = np.asarray(img)
-            result = jnp.array(arr)
-            for effect in effects_list:
-                op = effect['op']
-                if op == 'rotate':
-                    angle = dynamic_params.get('rotate_angle', effect.get('angle', 0))
-                    result = _jax_fused_fns['rotate'](result, angle=angle)
-                elif op == 'zoom':
-                    amount = dynamic_params.get('zoom_amount', effect.get('amount', 1.0))
-                    result = _jax_fused_fns['zoom'](result, amount=amount)
-                elif op == 'hue_shift':
-                    degrees = effect.get('degrees', 0)
-                    if abs(degrees) > 0.1:
-                        result = _jax_fused_fns['hue_shift'](result, degrees=degrees)
-                elif op == 'ripple':
-                    amplitude = dynamic_params.get('ripple_amplitude', effect.get('amplitude', 10))
-                    if amplitude > 0.1:
-                        result = _jax_fused_fns['ripple'](result,
-                            amplitude=amplitude,
-                            frequency=effect.get('frequency', 8),
-                            decay=effect.get('decay', 2),
-                            phase=dynamic_params.get('ripple_phase', effect.get('phase', 0)),
-                            cx=effect.get('center_x'),
-                            cy=effect.get('center_y'))
-                elif op == 'brightness':
-                    factor = effect.get('factor', 1.0)
-                    result = _jax_fused_fns['brightness'](result, factor=factor)
-                elif op == 'invert':
-                    amount = effect.get('amount', 0)
-                    if amount > 0.5:
-                        result = _jax_fused_fns['invert'](result)
-                else:
-                    raise ValueError(f"Unsupported fused pipeline operation: '{op}'. Supported ops: rotate, zoom, hue_shift, ripple, brightness, invert, resize")
-            return np.asarray(result)
+                raise ValueError(f"Unsupported fused pipeline operation: '{op}'. Supported ops: rotate, zoom, hue_shift, ripple, brightness, invert, resize")
+        return np.asarray(result)
+
+    if not _FUSED_KERNELS_AVAILABLE:
 
         # Legacy CuPy/GPUFrame fallback
         print(f"[FUSED FALLBACK] Using legacy GPUFrame path for {len(effects_list)} effects", file=sys.stderr)