Fix 25+ bugs across rounds 4-8 of comprehensive code review

history_tree.py:
- Cycle protection in generate_graph() parent walk
- KeyError → .get() for malformed node data in commit() and generate_graph()
- UUID collision check with for/else raise in commit() and _migrate_legacy()
- RuntimeError → ValueError for consistent exception handling

tab_timeline_ng.py:
- Re-parent children walks to surviving ancestor for batch deletes
- Branch tip deletion re-points to parent instead of removing branch
- Cycle protection in _walk_branch_nodes and _find_branch_for_node
- Full data.clear() restore instead of merge in _restore_node
- Safe .get('data', {}) in restore and preview
- Reset stale branch selection after node deletion
- json.dumps for safe JS string escaping in graphviz renderer

tab_batch_ng.py:
- NaN/inf rejection in dict_number with math.isfinite()
- _safe_int used in recalc_vace, update_mode_label, frame_to_skip
- Uncaught ValueError from htree.commit() caught with user notification

tab_comfy_ng.py:
- asyncio.get_event_loop() → get_running_loop()

utils.py:
- Atomic writes for save_config and save_snippets
- save_config extra_data can't override explicit last_dir/favorites

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

history_tree.py

@@ -18,7 +18,10 @@ class HistoryTree:
     def _migrate_legacy(self, old_list: list[dict[str, Any]]) -> None:
         parent = None
         for item in reversed(old_list):
-            node_id = str(uuid.uuid4())[:8]
+            for _ in range(10):
+                node_id = str(uuid.uuid4())[:8]
+                if node_id not in self.nodes:
+                    break
             self.nodes[node_id] = {
                 "id": node_id, "parent": parent, "timestamp": time.time(),
                 "data": item, "note": item.get("note", "Legacy Import")
@@ -28,7 +31,13 @@ class HistoryTree:
         self.head_id = parent
 
     def commit(self, data: dict[str, Any], note: str = "Snapshot") -> str:
-        new_id = str(uuid.uuid4())[:8]
+        # Generate unique node ID with collision check
+        for _ in range(10):
+            new_id = str(uuid.uuid4())[:8]
+            if new_id not in self.nodes:
+                break
+        else:
+            raise ValueError("Failed to generate unique node ID after 10 attempts")
 
         # Cycle detection: walk parent chain from head to verify no cycle
         if self.head_id:
@@ -39,7 +48,7 @@ class HistoryTree:
                     raise ValueError(f"Cycle detected in history tree at node {current}")
                 visited.add(current)
                 node = self.nodes.get(current)
-                current = node["parent"] if node else None
+                current = node.get("parent") if node else None
 
         active_branch = None
         for b_name, tip_id in self.branches.items():
@@ -115,8 +124,12 @@ class HistoryTree:
         # Build reverse lookup: node_id -> branch name (walk each branch ancestry)
         node_to_branch: dict[str, str] = {}
         for b_name, tip_id in self.branches.items():
+            visited = set()
             current = tip_id
             while current and current in self.nodes:
+                if current in visited:
+                    break
+                visited.add(current)
                 if current not in node_to_branch:
                     node_to_branch[current] = b_name
                 current = self.nodes[current].get('parent')
@@ -192,11 +205,18 @@ class HistoryTree:
                 + '</TABLE>>'
             )
 
-            safe_tooltip = full_note.replace('\\', '\\\\').replace('"', '\\"')
+            safe_tooltip = (full_note
-            dot.append(f'  "{nid}" [label={label}, tooltip="{safe_tooltip}"];')
+                .replace('\\', '\\\\')
+                .replace('"', '\\"')
+                .replace('\n', ' ')
+                .replace('\r', '')
+                .replace(']', '&#93;'))
+            safe_nid = nid.replace('"', '_')
+            dot.append(f'  "{safe_nid}" [label={label}, tooltip="{safe_tooltip}"];')
 
-            if n["parent"] and n["parent"] in self.nodes:
+            if n.get("parent") and n["parent"] in self.nodes:
-                dot.append(f'  "{n["parent"]}" -> "{nid}";')
+                safe_parent = n["parent"].replace('"', '_')
+                dot.append(f'  "{safe_parent}" -> "{safe_nid}";')
 
         dot.append("}")
         return "\n".join(dot)

tab_batch_ng.py

@@ -1,5 +1,6 @@
 import copy
 import json
+import math
 import random
 from pathlib import Path
 
@@ -143,6 +144,8 @@ def dict_number(label, seq, key, default=0, **kwargs):
     try:
         # Try float first to handle "1.5" strings, then check if it's a clean int
         fval = float(val)
+        if not math.isfinite(fval):
+            fval = float(default)
         val = int(fval) if fval == int(fval) else fval
     except (ValueError, TypeError, OverflowError):
         val = default
@@ -153,10 +156,13 @@ def dict_number(label, seq, key, default=0, **kwargs):
         if v is None:
             v = d
         elif isinstance(v, float):
-            try:
+            if not math.isfinite(v):
-                v = int(v) if v == int(v) else v
-            except (OverflowError, ValueError):
                 v = d
+            else:
+                try:
+                    v = int(v) if v == int(v) else v
+                except (OverflowError, ValueError):
+                    v = d
         seq[k] = v
 
     el.on('blur', lambda _: _sync())
@@ -336,7 +342,11 @@ def render_batch_processor(state: AppState):
                 snapshot_payload = copy.deepcopy(data)
                 snapshot_payload.pop(KEY_HISTORY_TREE, None)
                 note = commit_input.value if commit_input.value else _auto_change_note(htree, batch_list)
-                htree.commit(snapshot_payload, note=note)
+                try:
+                    htree.commit(snapshot_payload, note=note)
+                except ValueError as e:
+                    ui.notify(f'Save failed: {e}', type='negative')
+                    return
                 data[KEY_HISTORY_TREE] = htree.to_dict()
                 save_json(file_path, data)
                 if state.db_enabled and state.current_project and state.db:
@@ -635,18 +645,18 @@ def _render_vace_settings(i, seq, batch_list, data, file_path, state, refresh_li
                 fts_input = dict_number('Frame to Skip', seq, 'frame_to_skip').classes(
                     'col').props('outlined')
 
-                _original_fts = int(seq.get('frame_to_skip', FRAME_TO_SKIP_DEFAULT))
+                _original_fts = _safe_int(seq.get('frame_to_skip', FRAME_TO_SKIP_DEFAULT), FRAME_TO_SKIP_DEFAULT)
 
                 def shift_fts(idx=i, orig=_original_fts):
-                    new_fts = int(fts_input.value) if fts_input.value is not None else orig
+                    new_fts = _safe_int(fts_input.value, orig)
                     delta = new_fts - orig
                     if delta == 0:
                         ui.notify('No change to shift', type='info')
                         return
                     shifted = 0
                     for j in range(idx + 1, len(batch_list)):
-                        batch_list[j]['frame_to_skip'] = int(
+                        batch_list[j]['frame_to_skip'] = _safe_int(
-                            batch_list[j].get('frame_to_skip', FRAME_TO_SKIP_DEFAULT)) + delta
+                            batch_list[j].get('frame_to_skip', FRAME_TO_SKIP_DEFAULT), FRAME_TO_SKIP_DEFAULT) + delta
                         shifted += 1
                     data[KEY_BATCH_DATA] = batch_list
                     save_json(file_path, data)
@@ -670,7 +680,7 @@ def _render_vace_settings(i, seq, batch_list, data, file_path, state, refresh_li
                 ui.button(icon='help', on_click=ref_dlg.open).props('flat dense round')
 
                 def update_mode_label(e):
-                    idx = int(e.sender.value) if e.sender.value is not None else 0
+                    idx = _safe_int(e.sender.value, 0)
                     idx = max(0, min(idx, len(VACE_MODES) - 1))
                     mode_label.set_text(VACE_MODES[idx])
 
@@ -706,10 +716,10 @@ def _render_vace_settings(i, seq, batch_list, data, file_path, state, refresh_li
 
     # Recalculate VACE output when any input changes
     def recalc_vace(*_args):
-        mi = int(vs_input.value) if vs_input.value is not None else 0
+        mi = _safe_int(vs_input.value, 0)
-        ia = int(ia_input.value) if ia_input.value is not None else 16
+        ia = _safe_int(ia_input.value, 16)
-        ib = int(ib_input.value) if ib_input.value is not None else 16
+        ib = _safe_int(ib_input.value, 16)
-        nb = int(vl_input.value) if vl_input.value is not None else 1
+        nb = _safe_int(vl_input.value, 1)
 
         if mi == 0:
             raw = nb + ia
@@ -794,7 +804,11 @@ def _render_mass_update(batch_list, data, file_path, state: AppState, refresh_li
             htree = HistoryTree(data.get(KEY_HISTORY_TREE, {}))
             snapshot = copy.deepcopy(data)
             snapshot.pop(KEY_HISTORY_TREE, None)
-            htree.commit(snapshot, f"Mass update: {', '.join(selected_keys)}")
+            try:
+                htree.commit(snapshot, f"Mass update: {', '.join(selected_keys)}")
+            except ValueError as e:
+                ui.notify(f'Mass update failed: {e}', type='negative')
+                return
             data[KEY_HISTORY_TREE] = htree.to_dict()
             save_json(file_path, data)
             if state.db_enabled and state.current_project and state.db:

tab_comfy_ng.py

@@ -139,7 +139,7 @@ def _render_single_instance(state: AppState, instance_config: dict, index: int,
 
     async def refresh_status():
         status_container.clear()
-        loop = asyncio.get_event_loop()
+        loop = asyncio.get_running_loop()
         res, err = await loop.run_in_executor(
             None, lambda: _fetch_blocking(f'{comfy_url}/queue'))
         with status_container:
@@ -237,7 +237,7 @@ def _render_single_instance(state: AppState, instance_config: dict, index: int,
 
         async def check_image():
             img_container.clear()
-            loop = asyncio.get_event_loop()
+            loop = asyncio.get_running_loop()
             res, err = await loop.run_in_executor(
                 None, lambda: _fetch_blocking(f'{comfy_url}/history', timeout=2))
             with img_container:

tab_timeline_ng.py

@@ -1,4 +1,5 @@
 import copy
+import json
 import time
 
 from nicegui import ui
@@ -9,16 +10,37 @@ from utils import save_json, sync_to_db, KEY_BATCH_DATA, KEY_HISTORY_TREE
 
 
 def _delete_nodes(htree, data, file_path, node_ids):
-    """Delete nodes with backup, branch cleanup, and head fallback."""
+    """Delete nodes with backup, branch cleanup, re-parenting, and head fallback."""
     if 'history_tree_backup' not in data:
         data['history_tree_backup'] = []
     data['history_tree_backup'].append(copy.deepcopy(htree.to_dict()))
     data['history_tree_backup'] = data['history_tree_backup'][-10:]
+    # Save deleted node parents before removal (needed for branch re-pointing)
+    deleted_parents = {}
+    for nid in node_ids:
+        deleted_node = htree.nodes.get(nid)
+        if deleted_node:
+            deleted_parents[nid] = deleted_node.get('parent')
+    # Re-parent children of deleted nodes — walk up to find a surviving ancestor
+    for nid in node_ids:
+        surviving_parent = deleted_parents.get(nid)
+        while surviving_parent in node_ids:
+            surviving_parent = deleted_parents.get(surviving_parent)
+        for child in htree.nodes.values():
+            if child.get('parent') == nid:
+                child['parent'] = surviving_parent
     for nid in node_ids:
         htree.nodes.pop(nid, None)
+    # Re-point branches whose tip was deleted to a surviving ancestor
     for b, tip in list(htree.branches.items()):
         if tip in node_ids:
-            del htree.branches[b]
+            new_tip = deleted_parents.get(tip)
+            while new_tip in node_ids:
+                new_tip = deleted_parents.get(new_tip)
+            if new_tip and new_tip in htree.nodes:
+                htree.branches[b] = new_tip
+            else:
+                del htree.branches[b]
     if htree.head_id in node_ids:
         if htree.nodes:
             htree.head_id = sorted(htree.nodes.values(),
@@ -153,8 +175,12 @@ def _render_batch_delete(htree, data, file_path, state, refresh_fn):
 def _walk_branch_nodes(htree, tip_id):
     """Walk parent pointers from tip, returning nodes newest-first."""
     nodes = []
+    visited = set()
     current = tip_id
     while current and current in htree.nodes:
+        if current in visited:
+            break
+        visited.add(current)
         nodes.append(htree.nodes[current])
         current = htree.nodes[current].get('parent')
     return nodes
@@ -173,10 +199,14 @@ def _find_active_branch(htree):
 def _find_branch_for_node(htree, node_id):
     """Return the branch name whose ancestry contains node_id, or None."""
     for b_name, tip_id in htree.branches.items():
+        visited = set()
         current = tip_id
         while current and current in htree.nodes:
+            if current in visited:
+                break
             if current == node_id:
                 return b_name
+            visited.add(current)
             current = htree.nodes[current].get('parent')
     return None
 
@@ -311,6 +341,10 @@ def _render_node_manager(all_nodes, htree, data, file_path, restore_fn, refresh_
                     _delete_nodes(htree, data, file_path, {sel_id})
                     if state and state.db_enabled and state.current_project and state.db:
                         sync_to_db(state.db, state.current_project, file_path, data)
+                    # Reset selection if branch was removed
+                    if selected['branch'] not in htree.branches:
+                        selected['branch'] = next(iter(htree.branches), None)
+                    selected['node_id'] = htree.head_id
                     ui.notify('Node Deleted', type='positive')
                     refresh_fn()
 
@@ -434,7 +468,7 @@ def _render_graphviz(dot_source: str, selected_node_id: str | None = None):
         src = graphviz.Source(dot_source)
         svg = src.pipe(format='svg').decode('utf-8')
 
-        sel_escaped = selected_node_id.replace("'", "\\'") if selected_node_id else ''
+        sel_escaped = json.dumps(selected_node_id or '')[1:-1]  # strip quotes, get JS-safe content
 
         # CSS inline (allowed), JS via run_javascript (script tags blocked)
         css = '''<style>
@@ -491,11 +525,18 @@ def _render_graphviz(dot_source: str, selected_node_id: str | None = None):
 
 
 def _restore_node(data, node, htree, file_path, state: AppState):
-    """Restore a history node as the current version."""
+    """Restore a history node as the current version (full replace, not merge)."""
-    node_data = copy.deepcopy(node['data'])
+    node_data = copy.deepcopy(node.get('data', {}))
-    if KEY_BATCH_DATA not in node_data and KEY_BATCH_DATA in data:
+    # Preserve the history tree before clearing
-        del data[KEY_BATCH_DATA]
+    preserved_tree = data.get(KEY_HISTORY_TREE)
+    preserved_backup = data.get('history_tree_backup')
+    data.clear()
     data.update(node_data)
+    # Re-attach history tree (not part of snapshot data)
+    if preserved_tree is not None:
+        data[KEY_HISTORY_TREE] = preserved_tree
+    if preserved_backup is not None:
+        data['history_tree_backup'] = preserved_backup
     htree.head_id = node['id']
     data[KEY_HISTORY_TREE] = htree.to_dict()
     save_json(file_path, data)
@@ -512,7 +553,7 @@ def _render_data_preview(nid, htree):
         ui.label('No node selected.').classes('text-caption')
         return
 
-    node_data = htree.nodes[nid]['data']
+    node_data = htree.nodes[nid].get('data', {})
     batch_list = node_data.get(KEY_BATCH_DATA, [])
 
     if batch_list and isinstance(batch_list, list) and len(batch_list) > 0:

utils.py

@@ -114,14 +114,17 @@ def save_config(current_dir, favorites, extra_data=None):
     existing = load_config()
     data.update(existing)
     
-    data["last_dir"] = str(current_dir)
-    data["favorites"] = favorites
-    
     if extra_data:
         data.update(extra_data)
 
-    with open(CONFIG_FILE, 'w') as f:
+    # Force-set explicit params last so extra_data can't override them
+    data["last_dir"] = str(current_dir)
+    data["favorites"] = favorites
+
+    tmp = CONFIG_FILE.with_suffix('.json.tmp')
+    with open(tmp, 'w') as f:
         json.dump(data, f, indent=4)
+    os.replace(tmp, CONFIG_FILE)
 
 def load_snippets():
     if SNIPPETS_FILE.exists():
@@ -133,8 +136,10 @@ def load_snippets():
     return {}
 
 def save_snippets(snippets):
-    with open(SNIPPETS_FILE, 'w') as f:
+    tmp = SNIPPETS_FILE.with_suffix('.json.tmp')
+    with open(tmp, 'w') as f:
         json.dump(snippets, f, indent=4)
+    os.replace(tmp, SNIPPETS_FILE)
 
 def load_json(path: str | Path) -> tuple[dict[str, Any], float]:
     path = Path(path)