Fix project reopen persistence

Reviewed-on: #9

backend/gds_builder.py

@@ -4,12 +4,11 @@
 # Developer : Qin Yue @ 2026
 # Organization : OptiHK Limited
 # -----------------------------------------------------------------------------
-import os
+import tempfile
 from dataclasses import dataclass, field
-from typing import Dict, List
-
-import yaml
+from typing import List
 
+from layout_files import load_layout_cell_files, write_layout_cells_to_directory
 from router_dependency import require_router_stack
 
 
@@ -31,16 +30,25 @@ def build_project_gds(
     prefer_full_gds: bool = False,
 ) -> BuildResult:
     """Build a hierarchical project GDS from saved cell YAML files with mxpic_router."""
-    cells = _load_project_cells(project_dir)
+    cells, warnings = _load_project_cells(project_dir)
     if not cells:
         raise ValueError("No saved cell YAML files found for this project")
 
-    return _build_with_mxpic_router(
-        project_dir,
-        output_path,
-        pdk_public_root,
-        technology_manifest_path,
-        prefer_full_gds,
+    with tempfile.TemporaryDirectory(prefix="mxpic_gds_project_") as staged_project_dir:
+        write_layout_cells_to_directory(cells, staged_project_dir)
+        result = _build_with_mxpic_router(
+            staged_project_dir,
+            output_path,
+            pdk_public_root,
+            technology_manifest_path,
+            prefer_full_gds,
+        )
+
+    return BuildResult(
+        output_path=result.output_path,
+        engine=result.engine,
+        cells_built=result.cells_built,
+        warnings=warnings + result.warnings,
     )
 
 
@@ -70,15 +78,6 @@ def _build_with_mxpic_router(
     )
 
 
-def _load_project_cells(project_dir: str) -> Dict[str, dict]:
+def _load_project_cells(project_dir: str):
     """Load saved cell YAML documents from a project directory."""
-    cells = {}
-    for filename in sorted(os.listdir(project_dir)):
-        if not filename.lower().endswith((".yml", ".yaml")):
-            continue
-        path = os.path.join(project_dir, filename)
-        with open(path, "r", encoding="utf-8") as file:
-            data = yaml.safe_load(file) or {}
-        cell_name = str(data.get("name") or os.path.splitext(filename)[0])
-        cells[cell_name] = data
-    return cells
+    return load_layout_cell_files(project_dir)

backend/layout_files.py

@@ -0,0 +1,126 @@
+# -----------------------------------------------------------------------------
+# Description: Layout YAML file filtering, parsing, and staging helpers.
+# Inside functions: is_layout_cell_filename, parse_layout_cell_content, read_layout_cell_file, load_layout_cell_files, layout_cell_filename, write_layout_cells_to_directory
+# Developer : Qin Yue @ 2026
+# Organization : OptiHK Limited
+# -----------------------------------------------------------------------------
+import os
+import re
+
+import yaml
+
+
+LAYOUT_YAML_EXTENSIONS = (".yml", ".yaml")
+ROUTE_SIDECAR_SUFFIXES = (".routes.yml", ".routes.yaml")
+
+
+class LayoutFileError(ValueError):
+    """Raised when a saved layout YAML file cannot be used as a cell."""
+
+
+def is_layout_cell_filename(filename):
+    """Return True for user layout cell YAML files, excluding sidecars/manifests."""
+    lower = (filename or "").lower()
+    if lower == "technology.yml":
+        return False
+    if lower.endswith(ROUTE_SIDECAR_SUFFIXES):
+        return False
+    return lower.endswith(LAYOUT_YAML_EXTENSIONS)
+
+
+def is_layout_cell_document(data):
+    """Return True when parsed YAML looks like an mxPIC saved cell/project."""
+    if not isinstance(data, dict):
+        return False
+
+    kind = data.get("kind")
+    if kind and str(kind).strip().lower() != "cell":
+        return False
+
+    layout_keys = {
+        "schema_version",
+        "canvas_size",
+        "canvasSize",
+        "instances",
+        "elements",
+        "pins",
+        "ports",
+        "bundles",
+    }
+    return any(key in data for key in layout_keys)
+
+
+def parse_layout_cell_content(content, source="layout YAML"):
+    """Parse and validate saved layout YAML content."""
+    try:
+        data = yaml.safe_load(content or "") or {}
+    except yaml.YAMLError as exc:
+        raise LayoutFileError(f"{source} is not valid YAML: {exc}") from exc
+
+    if not is_layout_cell_document(data):
+        raise LayoutFileError(f"{source} is not a saved mxPIC layout cell")
+    return data
+
+
+def read_layout_cell_file(path):
+    """Read a saved layout cell file and return parsed data plus raw content."""
+    try:
+        with open(path, "r", encoding="utf-8") as file:
+            content = file.read()
+    except OSError as exc:
+        raise LayoutFileError(f"{os.path.basename(path)} could not be read: {exc}") from exc
+    return parse_layout_cell_content(content, os.path.basename(path)), content
+
+
+def load_layout_cell_files(project_dir):
+    """Load valid layout cell files from a project directory and collect warnings."""
+    cells = []
+    warnings = []
+    if not os.path.isdir(project_dir):
+        return cells, warnings
+
+    for filename in sorted(os.listdir(project_dir)):
+        if not is_layout_cell_filename(filename):
+            continue
+        path = os.path.join(project_dir, filename)
+        if not os.path.isfile(path):
+            continue
+        try:
+            data, content = read_layout_cell_file(path)
+        except LayoutFileError as exc:
+            warnings.append(f"Skipped {filename}: {exc}")
+            continue
+
+        cells.append({
+            "filename": filename,
+            "name": str(data.get("name") or os.path.splitext(filename)[0]),
+            "data": data,
+            "content": content,
+        })
+    return cells, warnings
+
+
+def layout_cell_filename(cell_name, fallback="canvas_1.yml"):
+    """Build a safe filename for staging a parsed layout cell."""
+    name = re.sub(r"[^A-Za-z0-9_.-]+", "_", str(cell_name or "")).strip("._")
+    if not name:
+        return fallback
+    return f"{name}.yml"
+
+
+def write_layout_cells_to_directory(cells, output_dir):
+    """Write valid layout cell contents into a clean staging directory."""
+    os.makedirs(output_dir, exist_ok=True)
+    used_names = set()
+    for index, cell in enumerate(cells, start=1):
+        filename = layout_cell_filename(cell.get("name"), cell.get("filename") or f"cell_{index}.yml")
+        base, ext = os.path.splitext(filename)
+        unique_filename = filename
+        counter = 1
+        while unique_filename.lower() in used_names:
+            counter += 1
+            unique_filename = f"{base}_{counter}{ext}"
+        used_names.add(unique_filename.lower())
+
+        with open(os.path.join(output_dir, unique_filename), "w", encoding="utf-8") as file:
+            file.write(cell["content"])

backend/routed_layout_preview.py

@@ -9,6 +9,7 @@ import tempfile
 
 import yaml
 
+from layout_files import load_layout_cell_files, write_layout_cells_to_directory
 from router_dependency import require_router_stack
 
 
@@ -32,9 +33,20 @@ def create_routed_layout_svg(
     # Build into a temporary GDS first, then convert the generated top cell into
     # the SVG preview consumed by the canvas.
     with tempfile.TemporaryDirectory(prefix="mxpic_routed_preview_") as temp_dir:
+        staged_project_dir = os.path.join(temp_dir, "project")
+        saved_cells, _warnings = load_layout_cell_files(project_dir)
+        staged_cells = [cell for cell in saved_cells if cell["name"] != cell_name]
+        staged_cells.append({
+            "filename": f"{cell_name}.yml",
+            "name": cell_name,
+            "data": layout,
+            "content": yaml_content,
+        })
+        write_layout_cells_to_directory(staged_cells, staged_project_dir)
+
         temp_gds = os.path.join(temp_dir, f"{cell_name}.gds")
         build_project_gds(
-            project_dir=project_dir,
+            project_dir=staged_project_dir,
             output_path=temp_gds,
             pdk_root=pdk_root,
             technology_manifest_path=technology_manifest_path,

backend/server.py

@@ -18,6 +18,13 @@ from werkzeug.security import check_password_hash
 import database  
 from flask import Response
 from gds_builder import build_project_gds
+from layout_files import (
+    LayoutFileError,
+    is_layout_cell_filename,
+    load_layout_cell_files,
+    parse_layout_cell_content,
+    read_layout_cell_file,
+)
 from pdk_access import (
     cleanup_expired_exports,
     create_export_path,
@@ -145,13 +152,17 @@ def cell_routes_path(project_name, cell_name):
 
 def write_route_points_sidecar(yaml_content, output_path):
     """Extract route points from layout YAML and save them beside the cell."""
-    layout = yaml.safe_load(yaml_content) or {}
+    layout = yaml_content if isinstance(yaml_content, dict) else parse_layout_cell_content(yaml_content)
     routes = {}
     # The sidecar preserves manually edited route control points separately from
     # the main YAML file for tooling that wants route-only metadata.
     for bundle_name, bundle in (layout.get("bundles") or {}).items():
+        if not isinstance(bundle, dict):
+            continue
         saved_links = []
         for link in bundle.get("links") or []:
+            if not isinstance(link, dict):
+                continue
             points = link.get("points") or []
             if not points:
                 continue
@@ -587,22 +598,24 @@ def list_projects():
     os.makedirs(root, exist_ok=True)
 
     projects = []
-    # Each project is a folder and each YAML file inside that folder is treated
-    # as one saved cell/canvas.
+    # Each project is a folder and each valid layout YAML file inside that
+    # folder is treated as one saved cell/canvas. Route sidecars and malformed
+    # files are ignored so reopen stays resilient to stale runtime artifacts.
     for name in sorted(os.listdir(root)):
         path = os.path.join(root, name)
         if not os.path.isdir(path):
             continue
         cells = []
         for filename in sorted(os.listdir(path)):
-            if not filename.lower().endswith(('.yml', '.yaml')):
+            if not is_layout_cell_filename(filename):
                 continue
             cell_name = os.path.splitext(filename)[0]
             yml_path = os.path.join(path, filename)
-            cells.append({
-                "name": cell_name,
-                "has_layout": os.path.exists(yml_path)
-            })
+            try:
+                read_layout_cell_file(yml_path)
+            except LayoutFileError:
+                continue
+            cells.append({"name": cell_name, "has_layout": True})
         meta = read_project_meta(name)
         projects.append({
             "name": name,
@@ -648,24 +661,20 @@ def get_project(project_name):
     if not os.path.isdir(root):
         return jsonify({"error": "Project not found"}), 404
 
-    cells = []
-    for filename in sorted(os.listdir(root)):
-        if not filename.lower().endswith(('.yml', '.yaml')):
-            continue
-        cell_name = os.path.splitext(filename)[0]
-        yml_path = os.path.join(root, filename)
-        if not os.path.exists(yml_path):
-            continue
-        with open(yml_path, 'r', encoding='utf-8') as f:
-            cells.append({
-                "name": cell_name,
-                "content": f.read()
-            })
+    loaded_cells, warnings = load_layout_cell_files(root)
+    cells = [
+        {
+            "name": os.path.splitext(cell["filename"])[0],
+            "content": cell["content"]
+        }
+        for cell in loaded_cells
+    ]
 
     return jsonify({
         "name": safe_name(project_name, 'project_1'),
         "cells": cells,
-        "technology": read_project_meta(project_name).get("technology")
+        "technology": read_project_meta(project_name).get("technology"),
+        "warnings": warnings
     })
 
 
@@ -728,18 +737,19 @@ def rename_cell(project_name, cell_name):
 def save_layout():
     """Persist a canvas layout YAML document and refresh its preview assets."""
     try:
-        data = request.get_json()
+        data = request.get_json(silent=True) or {}
         project = safe_name(data.get('project'), 'project_1')
         cell = safe_name(data.get('cell'), 'canvas_1')
         content = data.get('content', '')
         create_preview = bool(data.get('preview', True))
+        layout_doc = parse_layout_cell_content(content, f"{project}/{cell}.yml")
 
         save_path = cell_file_path(project, cell)
         os.makedirs(os.path.dirname(save_path), exist_ok=True)
 
         with open(save_path, 'w', encoding='utf-8') as f:
             f.write(content)
-        write_route_points_sidecar(content, cell_routes_path(project, cell))
+        write_route_points_sidecar(layout_doc, cell_routes_path(project, cell))
 
         svg_path = None
         svg_version = None
@@ -782,6 +792,8 @@ def save_layout():
             "preview_error": preview_error
         }), 200
 
+    except LayoutFileError as e:
+        return jsonify({"error": str(e)}), 400
     except Exception as e:
         return jsonify({"error": str(e)}), 500
 

frontend/canvas-helpers.js

@@ -1282,6 +1282,22 @@ bundles:${groupsYaml ? `\n${groupsYaml}` : ' {}'}`;
     return null;
   };
 
+  const getRotatableNodeHandleDirection = (node, handleId) => {
+    if (!node || !handleId) return null;
+    if (node.type !== 'rotatableNode' && !(!node.data?.elementType && node.data?.componentName)) return null;
+    const ports = node.data && node.data.ports;
+    if (!ports || !ports[handleId]) return null;
+    const boxSize = normalizeBoxSize({ box_size: node.data && node.data.boxSize }, DEFAULT_COMPONENT_BOX_SIZE);
+    const handles = buildPortHandles(ports, {
+      rotation: Number((node.data && node.data.rotation) || 0),
+      flip: Boolean(node.data && node.data.flip),
+      flop: Boolean(node.data && node.data.flop),
+      boxSize
+    });
+    const found = handles.find(handle => handle.name === handleId);
+    return found ? found.position : null;
+  };
+
   // Backward-compatible alias for same-type route crossing validation.
   const findSameFamilyRouteCrossing = findSameTypeRouteCrossing;
 
@@ -1324,6 +1340,7 @@ bundles:${groupsYaml ? `\n${groupsYaml}` : ' {}'}`;
     createComponentSymbolMetrics,
     transformPortInfo,
     getNodePortCanvasPoint,
+    getRotatableNodeHandleDirection,
     buildPortHandles,
     buildElementPorts,
     buildElementPinEntries,

frontend/canvas.html

@@ -1566,6 +1566,7 @@ Organization : OptiHK Limited
       calculateLayoutBounds,
       calculateCompositeBoxSize,
       buildPortHandles,
+      getRotatableNodeHandleDirection,
       buildElementPorts,
       getElementPinName,
       buildElementBoxSize,
@@ -1710,8 +1711,10 @@ Organization : OptiHK Limited
       useEffect(() => {
         const transformKey = `${data.rotation || 0}:${data.flip ? 1 : 0}:${data.flop ? 1 : 0}`;
         if (prevTransformRef.current !== transformKey) {
-          updateNodeInternalsRef.current(id);
           prevTransformRef.current = transformKey;
+          requestAnimationFrame(() => {
+            updateNodeInternalsRef.current(id);
+          });
         }
       }, [data.rotation, data.flip, data.flop, id]);
 
@@ -1731,6 +1734,16 @@ Organization : OptiHK Limited
         top: Position.Top,
         bottom: Position.Bottom
       };
+      const rotateHandleDirection = (dir, rot) => {
+        const norm = ((rot % 360) + 360) % 360;
+        const map = {
+          0: { right: 'right', left: 'left', top: 'top', bottom: 'bottom' },
+          90: { right: 'bottom', left: 'top', top: 'left', bottom: 'right' },
+          180: { right: 'left', left: 'right', top: 'bottom', bottom: 'top' },
+          270: { right: 'top', left: 'bottom', top: 'right', bottom: 'left' }
+        };
+        return (map[norm] || map[0])[dir] || dir;
+      };
       const componentSize = normalizeBoxSize({ box_size: data.boxSize }, DEFAULT_COMPONENT_BOX_SIZE);
       const flippedPorts = useMemo(
         () => {
@@ -1856,24 +1869,28 @@ Organization : OptiHK Limited
             transformOrigin: 'center center',
             pointerEvents: 'none'
           }}>
-            {portHandles.map((portHandle) => (
+            {portHandles.map((portHandle) => {
+              const originalDir = portDirectionMap.get(portHandle.name) || portHandle.position;
+              const effectiveDir = rotateHandleDirection(originalDir, data.rotation || 0);
+              return (
               <React.Fragment key={portHandle.name}>
                 <Handle
                   type="source"
-                  position={handlePositionMap[portDirectionMap.get(portHandle.name) || portHandle.position]}
+                  position={handlePositionMap[effectiveDir]}
                   id={portHandle.name}
                   title={portHandle.name}
                   style={{ ...baseHandleStyle, ...portHandle.style, zIndex: 10, pointerEvents: 'all' }}
                 />
                 <Handle
                   type="target"
-                  position={handlePositionMap[portDirectionMap.get(portHandle.name) || portHandle.position]}
+                  position={handlePositionMap[effectiveDir]}
                   id={portHandle.name}
                   title={portHandle.name}
                   style={{ ...baseHandleStyle, ...portHandle.style, zIndex: 5, pointerEvents: 'all' }}
                 />
               </React.Fragment>
-            ))}
+              );
+            })}
             {portHandles.map((portHandle) => (
               <span key={`label-${portHandle.name}`} className="port-name-label" style={portLabelStyle(portHandle)} title={portHandle.name}>
                 {portHandle.name}
@@ -2229,24 +2246,73 @@ Organization : OptiHK Limited
 
     // Displays generated layout SVG previews with zoom and pan controls.
     const LayoutSvgPreview = ({ page }) => {
-      const [layoutScale, setLayoutScale] = useState(100);
+      const [layoutScale, setLayoutScale] = useState(null);
+      const [previewViewport, setPreviewViewport] = useState({ width: 1, height: 1 });
+      const [svgSize, setSvgSize] = useState(null);
+      const previewCanvasRef = useRef(null);
       const previewBounds = useMemo(
         () => page.layoutBounds || calculateLayoutBounds(page),
         [page.layoutBounds, page.nodes, page.canvasSize]
       );
-      const normalizedScale = Math.min(800, Math.max(10, Number(layoutScale) || 100));
-      const stageWidth = Math.max(1, previewBounds.width) * normalizedScale / 100;
-      const stageHeight = Math.max(1, previewBounds.height) * normalizedScale / 100;
+      const minLayoutScale = 0.01;
+      const maxLayoutScale = 800;
+      const scalePrecision = 100;
+      const clampLayoutScale = (value, fallback = 100) => {
+        const numericValue = Number(value);
+        const scale = Number.isFinite(numericValue) && numericValue > 0 ? numericValue : fallback;
+        return Number(Math.min(maxLayoutScale, Math.max(minLayoutScale, scale)).toFixed(2));
+      };
+      const baseWidth = Math.max(1, svgSize?.width || previewBounds.width);
+      const baseHeight = Math.max(1, svgSize?.height || previewBounds.height);
+      const availableWidth = Math.max(1, previewViewport.width);
+      const availableHeight = Math.max(1, previewViewport.height);
+      const rawFitScalePercent = Math.min(availableWidth / baseWidth, availableHeight / baseHeight) * 100;
+      const fitScalePercent = clampLayoutScale(Math.floor(rawFitScalePercent * scalePrecision) / scalePrecision);
+      const normalizedScale = clampLayoutScale(layoutScale ?? fitScalePercent, fitScalePercent);
+      const stageWidth = baseWidth * normalizedScale / 100;
+      const stageHeight = baseHeight * normalizedScale / 100;
+
+      useEffect(() => {
+        const previewCanvas = previewCanvasRef.current;
+        if (!previewCanvas) return undefined;
+
+        const measurePreviewViewport = () => {
+          const styles = window.getComputedStyle(previewCanvas);
+          const paddingX = (parseFloat(styles.paddingLeft) || 0) + (parseFloat(styles.paddingRight) || 0);
+          const paddingY = (parseFloat(styles.paddingTop) || 0) + (parseFloat(styles.paddingBottom) || 0);
+          setPreviewViewport({
+            width: Math.max(1, previewCanvas.clientWidth - paddingX),
+            height: Math.max(1, previewCanvas.clientHeight - paddingY)
+          });
+        };
+
+        measurePreviewViewport();
+        if (typeof ResizeObserver === 'undefined') {
+          window.addEventListener('resize', measurePreviewViewport);
+          return () => window.removeEventListener('resize', measurePreviewViewport);
+        }
+
+        const observer = new ResizeObserver(measurePreviewViewport);
+        observer.observe(previewCanvas);
+        return () => observer.disconnect();
+      }, []);
 
       const updateScale = (value) => {
-        setLayoutScale(Math.min(800, Math.max(10, Number(value) || 100)));
+        setLayoutScale(clampLayoutScale(value, fitScalePercent));
       };
 
       const handleWheel = (event) => {
         event.preventDefault();
         const direction = event.deltaY > 0 ? -1 : 1;
         const step = event.shiftKey ? 5 : 15;
-        setLayoutScale(current => Math.min(800, Math.max(10, (Number(current) || 100) + direction * step)));
+        setLayoutScale(current => clampLayoutScale((current ?? fitScalePercent) + direction * step, fitScalePercent));
+      };
+
+      const handleSvgLoad = (event) => {
+        const image = event.currentTarget;
+        if (image.naturalWidth > 0 && image.naturalHeight > 0) {
+          setSvgSize({ width: image.naturalWidth, height: image.naturalHeight });
+        }
       };
 
       return (
@@ -2256,9 +2322,9 @@ Organization : OptiHK Limited
               Scale
               <input
                 type="range"
-                min="10"
-                max="800"
-                step="5"
+                min={minLayoutScale}
+                max={maxLayoutScale}
+                step="0.01"
                 value={normalizedScale}
                 onChange={(event) => updateScale(event.target.value)}
                 aria-label="Layout SVG preview scale"
@@ -2267,9 +2333,9 @@ Organization : OptiHK Limited
             <label>
               <input
                 type="number"
-                min="10"
-                max="800"
-                step="5"
+                min={minLayoutScale}
+                max={maxLayoutScale}
+                step="0.01"
                 value={normalizedScale}
                 onChange={(event) => updateScale(event.target.value)}
                 aria-label="Layout SVG preview scale percent"
@@ -2277,7 +2343,7 @@ Organization : OptiHK Limited
               %
             </label>
           </div>
-          <div className="layout-preview-canvas" onWheel={handleWheel}>
+          <div className="layout-preview-canvas" ref={previewCanvasRef} onWheel={handleWheel}>
             <div className="layout-preview-scroll-area">
               <div
                 className="layout-preview-stage"
@@ -2287,6 +2353,7 @@ Organization : OptiHK Limited
                   className="layout-preview-image"
                   src={page.svgUrl}
                   alt={`${page.name} layout preview`}
+                  onLoad={handleSvgLoad}
                   style={{ objectFit: 'contain' }}
                 />
               </div>
@@ -4127,8 +4194,10 @@ Organization : OptiHK Limited
           const targetEndpoint = `${edge.target}:${edge.targetHandle || ''}`;
           const key = [sourceEndpoint, targetEndpoint].sort().join('<>');
           const group = groups.get(key) || [];
-          const sourceDirection = getAnchorHandleRouteDirection(nodeMap[edge.source], edge.sourceHandle);
-          const targetDirection = getAnchorHandleRouteDirection(nodeMap[edge.target], edge.targetHandle);
+          const sourceDirection = getAnchorHandleRouteDirection(nodeMap[edge.source], edge.sourceHandle)
+            || getRotatableNodeHandleDirection(nodeMap[edge.source], edge.sourceHandle);
+          const targetDirection = getAnchorHandleRouteDirection(nodeMap[edge.target], edge.targetHandle)
+            || getRotatableNodeHandleDirection(nodeMap[edge.target], edge.targetHandle);
           const usesAnchorDirection = Boolean(sourceDirection || targetDirection);
           const hasRoutePoints = edge.data && Array.isArray(edge.data.points) && edge.data.points.length >= 2;
           const directionalEdge = usesAnchorDirection
@@ -4151,7 +4220,7 @@ Organization : OptiHK Limited
           };
         });
         return [...separatedEdges, ...rulerEdges];
-      }, [currentEdges, currentNodes, getAnchorHandleRouteDirection, rulerEdges]);
+      }, [currentEdges, currentNodes, getAnchorHandleRouteDirection, getRotatableNodeHandleDirection, rulerEdges]);
 
       const [projectCompositeMap, setProjectCompositeMap] = useState({});
       const [standaloneComposites, setStandaloneComposites] = useState([]);
@@ -5192,11 +5261,20 @@ Organization : OptiHK Limited
             }
 
             const data = await response.json();
+            (data.warnings || []).forEach(warning => addLog(warning));
             const technology = data.technology || '';
             setProjectTechnology(technology);
             const manifest = await loadTechnologyManifest(technology);
-            const knownCompositeNames = new Set((data.cells || []).map(cell => cell.name).filter(name => name !== currentProjectName));
-            const parsedCellPages = (data.cells || []).map(cell => pageFromYaml(cell.name, cell.content, manifest, knownCompositeNames));
+            const loadedCells = data.cells || [];
+            const knownCompositeNames = new Set(loadedCells.map(cell => cell.name).filter(name => name !== currentProjectName));
+            const parsedCellPages = [];
+            loadedCells.forEach(cell => {
+              try {
+                parsedCellPages.push(pageFromYaml(cell.name, cell.content, manifest, knownCompositeNames));
+              } catch (error) {
+                addLog(`Skipped saved cell "${cell.name}": ${error.message}`);
+              }
+            });
             const compositeBoxSizes = new Map(parsedCellPages
               .filter(page => page.type === 'composite')
               .map(page => [page.name, calculateCompositeBoxSize(page)]));
@@ -5258,7 +5336,7 @@ Organization : OptiHK Limited
         };
 
         loadProject();
-      }, [library, currentProjectName, loadTechnologyManifest, toBooleanFlag, makeFreeRouteEdge, buildElementNodesFromYaml, getAvailableComponentsForLoadedComponent, resolveLoadedPinHandle]);
+      }, [library, currentProjectName, loadTechnologyManifest, toBooleanFlag, makeFreeRouteEdge, buildElementNodesFromYaml, getAvailableComponentsForLoadedComponent, resolveLoadedPinHandle, addLog]);
 
       useEffect(() => {
         if (activePage && activePage.type !== 'layoutPreview' && reactFlowInstance) {
@@ -6130,6 +6208,7 @@ Organization : OptiHK Limited
         const route = currentLinkRoute;
         const view = routeStyleForSettings(route, false);
         const edgeId = `edge-${connection.source}-${connection.sourceHandle}-${connection.target}-${connection.targetHandle}-${Date.now()}`;
+        const nodeMap = Object.fromEntries(activePage.nodes.map(node => [node.id, node]));
         const candidate = {
           id: edgeId,
           source: connection.source,
@@ -6139,9 +6218,8 @@ Organization : OptiHK Limited
           type: view.type,
           selectable: true,
           style: view.style,
-          data: { route }
+          data: { route },
         };
-        const nodeMap = Object.fromEntries(activePage.nodes.map(node => [node.id, node]));
         const conflict = findSameTypeRouteCrossing(candidate, activePage.edges, nodeMap, technologyManifest);
         if (conflict) {
           const source = nodeMap[conflict.conflictEdge.source]?.data?.componentDisplayName || conflict.conflictEdge.source;
@@ -6155,7 +6233,7 @@ Organization : OptiHK Limited
             : p
         )));
         addLog(`Connected ${connection.sourceHandle} to ${connection.targetHandle}.`);
-      }, [activePageId, activePage, rulerMode, currentLinkRoute, technologyManifest, addLog]);
+      }, [activePageId, activePage, rulerMode, currentLinkRoute, technologyManifest, addLog, getAnchorHandleRouteDirection]);
 
       // Select custom route edges from their SVG hit target.
       const handleRouteEdgeMouseDown = useCallback((event) => {

tests/layout-backend-static.test.js

@@ -61,7 +61,6 @@ assert(
   'save-layout response should include an svg_url for the new layout tab'
 );
 assert(
-<<<<<<< HEAD
   serverPy.includes('svg_ready') &&
     serverPy.includes('svg_version') &&
     serverPy.includes('file_version(svg_path)') &&
@@ -74,8 +73,6 @@ assert(
   'save-layout should publish generated SVG previews atomically instead of serving partially written files'
 );
 assert(
-=======
->>>>>>> jingwen_main
   serverPy.includes('RouterStackUnavailable') &&
     serverPy.includes('except RouterStackUnavailable as e') &&
     serverPy.includes('"preview_status": preview_status') &&

tests/layout-ui-wiring.test.js

@@ -33,16 +33,6 @@ assert(
   'Build Layout should use the backend svg_url response'
 );
 assert(
-<<<<<<< HEAD
-  canvasHtml.includes('result.svg_ready && result.svg_url') &&
-    canvasHtml.includes('buildLayoutRequestRef') &&
-    canvasHtml.includes('buildLayoutBusyRef') &&
-    canvasHtml.includes("cache: 'no-store'"),
-  'Build Layout should wait for a ready, versioned SVG response and prevent stale duplicate preview updates'
-);
-assert(
-=======
->>>>>>> jingwen_main
   canvasHtml.includes('result.preview_error') &&
     canvasHtml.includes('Preview skipped: '),
   'Build Layout should log when the backend saves YAML but skips SVG preview because the router stack is unavailable'
@@ -60,8 +50,18 @@ assert(
   'layout SVG preview should expose an editable scale value'
 );
 assert(
-  canvasHtml.includes('objectFit: \'contain\''),
-  '100% layout preview scale should fit the full SVG within the screen'
+  canvasHtml.includes('objectFit: \'contain\'') &&
+    canvasHtml.includes('previewCanvasRef') &&
+    canvasHtml.includes('ResizeObserver') &&
+    canvasHtml.includes('svgSize') &&
+    canvasHtml.includes('naturalWidth') &&
+    canvasHtml.includes('naturalHeight') &&
+    canvasHtml.includes('const fitScalePercent = clampLayoutScale(Math.floor') &&
+    canvasHtml.includes('layoutScale ?? fitScalePercent') &&
+    canvasHtml.includes('const stageWidth = baseWidth * normalizedScale / 100') &&
+    !canvasHtml.includes('useState(100)') &&
+    !canvasHtml.includes('baseWidth * fitScale * normalizedScale / 100'),
+  'layout preview should default to the actual fitted SVG scale percent instead of redefining 100% as fit'
 );
 assert(
   canvasHtml.includes('className="build-gds-btn"'),
@@ -354,7 +354,7 @@ assert(
     canvasHtml.includes('layoutBounds') &&
     canvasHtml.includes('stageWidth') &&
     canvasHtml.includes('stageHeight'),
-  'layout preview should mouse-wheel zoom and size 100% from calculated box_size layout bounds'
+  'layout preview should mouse-wheel zoom from the actual calculated SVG scale'
 );
 assert(
   canvasHtml.includes('reactFlowInstance.fitBounds') &&

tests/project-persistence-static.test.js

@@ -0,0 +1,54 @@
+/*
+ * Description: Static regression tests for resilient project save/reopen behavior.
+ * Inside functions: N/A - assertion-based test/module script.
+ * Developer : Qin Yue @ 2026
+ * Organization : OptiHK Limited
+ */
+const assert = require('assert');
+const fs = require('fs');
+const path = require('path');
+
+const root = path.resolve(__dirname, '..');
+const backend = path.join(root, 'backend');
+const layoutFilesPath = path.join(backend, 'layout_files.py');
+const layoutFilesPy = fs.readFileSync(layoutFilesPath, 'utf8');
+const serverPy = fs.readFileSync(path.join(backend, 'server.py'), 'utf8');
+const gdsBuilderPy = fs.readFileSync(path.join(backend, 'gds_builder.py'), 'utf8');
+const routedPreviewPy = fs.readFileSync(path.join(backend, 'routed_layout_preview.py'), 'utf8');
+const canvasHtml = fs.readFileSync(path.join(root, 'frontend', 'canvas.html'), 'utf8');
+
+assert(
+  fs.existsSync(layoutFilesPath),
+  'backend/layout_files.py should centralize saved layout YAML filtering and parsing'
+);
+assert(
+  layoutFilesPy.includes('ROUTE_SIDECAR_SUFFIXES') &&
+    layoutFilesPy.includes('def is_layout_cell_filename') &&
+    layoutFilesPy.includes('def parse_layout_cell_content') &&
+    layoutFilesPy.includes('def load_layout_cell_files'),
+  'layout file helpers should exclude route sidecars and validate saved layout cells'
+);
+assert(
+  serverPy.includes('is_layout_cell_filename') &&
+    serverPy.includes('load_layout_cell_files(root)') &&
+    serverPy.includes('parse_layout_cell_content(content') &&
+    serverPy.includes('except LayoutFileError as e'),
+  'project list/load/save endpoints should filter invalid YAML and reject malformed saves'
+);
+assert(
+  gdsBuilderPy.includes('TemporaryDirectory(prefix="mxpic_gds_project_"') &&
+    gdsBuilderPy.includes('write_layout_cells_to_directory(cells, staged_project_dir)'),
+  'Build GDS should call mxpic_router with a clean staged project directory'
+);
+assert(
+  routedPreviewPy.includes('staged_project_dir') &&
+    routedPreviewPy.includes('write_layout_cells_to_directory(staged_cells, staged_project_dir)') &&
+    routedPreviewPy.includes('project_dir=staged_project_dir'),
+  'Build Layout preview should stage valid cells before calling mxpic_router'
+);
+assert(
+  canvasHtml.includes('(data.warnings || []).forEach(warning => addLog(warning))') &&
+    canvasHtml.includes('const parsedCellPages = [];') &&
+    canvasHtml.includes('Skipped saved cell'),
+  'canvas project loading should report skipped files and keep loading remaining valid cells'
+);