chore: checkpoint web Blender migration source, tools and docs

Accumulated uncommitted work: GHOST Web backend, WebGL/GPU web layer,
web workflow engine and protocol, tooling, docs and task records.
Large generated evidence, user-testing archives, build snapshots and
imported test assets remain untracked.

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

blender-5.2.0/source/blender/blenkernel/intern/pointcache.cc

@@ -8,6 +8,10 @@
  */
 
 #include <algorithm>
+#include <cerrno>
+#include <charconv>
+#include <memory>
+#include <vector>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
@@ -3453,7 +3457,7 @@ void BKE_ptcache_toggle_disk_cache(PTCacheID *pid)
   }
 }
 
-void BKE_ptcache_disk_cache_rename(PTCacheID *pid, const char *name_src, const char *name_dst)
+bool BKE_ptcache_disk_cache_rename(PTCacheID *pid, const char *name_src, const char *name_dst)
 {
   char old_name[80];
   int len; /* store the length of the string */
@@ -3468,46 +3472,99 @@ void BKE_ptcache_disk_cache_rename(PTCacheID *pid, const char *name_src, const c
 
   /* If both names are the same, there is nothing to do. */
   if (STREQ(name_src, name_dst)) {
-    return;
+    return true;
   }
 
   /* save old name */
   STRNCPY(old_name, pid->cache->name);
+  struct RestoreName {
+    PointCache *cache;
+    const char *name;
+    ~RestoreName() { STRNCPY(cache->name, name); }
+  } restore_name{pid->cache, old_name};
 
   /* get "from" filename */
   STRNCPY(pid->cache->name, name_src);
 
   len = ptcache_filepath(pid, old_filepath, 0, false, false); /* no path */
+  if (len <= 0) { CLOG_ERROR(&LOG, "Cannot rename point cache without a valid source filename"); return false; }
 
   BKE_ptcache_path(pid, path);
   dir = opendir(path);
   if (dir == nullptr) {
-    STRNCPY(pid->cache->name, old_name);
-    return;
+    if (errno == ENOENT && !(pid->cache->flag & PTCACHE_BAKED)) return true;
+    CLOG_ERROR(&LOG, "Cannot open point cache directory '%s': %s", path, std::strerror(errno));
+    return false;
   }
+  std::unique_ptr<DIR, decltype(&closedir)> directory(dir, closedir);
+  std::vector<int> frames;
+  bool found_source = false;
 
   ptcache_filepath_ext_append(pid, ext, 0, false, 0);
 
   /* put new name into cache */
   STRNCPY(pid->cache->name, name_dst);
 
-  while ((de = readdir(dir)) != nullptr) {
-    if (strstr(de->d_name, ext)) {                   /* Do we have the right extension? */
+  while (true) {
+    errno = 0;
+    de = readdir(dir);
+    if (!de) break;
+    const size_t name_len = strlen(de->d_name), ext_len = strlen(ext);
+    if (name_len > size_t(len) + 1 + ext_len && de->d_name[len] == '_' && STREQ(de->d_name + name_len - ext_len, ext)) {
       if (STREQLEN(old_filepath, de->d_name, len)) { /* Do we have the right prefix. */
         /* read the number of the file */
-        const int frame = ptcache_frame_from_filename(de->d_name, ext);
+        int frame;
+        const char *frame_end = de->d_name + name_len - ext_len;
+        const auto parsed = std::from_chars(de->d_name + len + 1, frame_end, frame);
 
-        if (frame != -1) {
+        if (parsed.ec == std::errc() && parsed.ptr == frame_end) {
+          char expected[MAX_PTCACHE_FILE];
+          STRNCPY(pid->cache->name, name_src);
+          const bool matches = ptcache_filepath(pid, expected, frame, false, true) > 0 && STREQ(expected, de->d_name);
+          STRNCPY(pid->cache->name, name_dst);
+          if (!matches) continue;
+          found_source = true;
           BLI_path_join(old_path_full, sizeof(old_path_full), path, de->d_name);
-          ptcache_filepath(pid, new_path_full, frame, true, true);
-          BLI_rename_overwrite(old_path_full, new_path_full);
+          if (ptcache_filepath(pid, new_path_full, frame, true, true) <= 0) { CLOG_ERROR(&LOG, "Invalid point-cache rename destination"); return false; }
+          if (STREQ(old_path_full, new_path_full)) continue;
+          if (BLI_exists(new_path_full)) { CLOG_ERROR(&LOG, "Point-cache rename destination already exists: '%s'", new_path_full); return false; }
+          try { frames.push_back(frame); }
+          catch (const std::bad_alloc &) { CLOG_ERROR(&LOG, "Not enough memory to plan point-cache rename"); return false; }
         }
       }
     }
   }
-  closedir(dir);
-
-  STRNCPY(pid->cache->name, old_name);
+  if (errno != 0) { CLOG_ERROR(&LOG, "Cannot enumerate point cache directory '%s': %s", path, std::strerror(errno)); return false; }
+  if (closedir(directory.release()) != 0) { CLOG_ERROR(&LOG, "Cannot close point cache directory '%s': %s", path, std::strerror(errno)); return false; }
+  if (!found_source && (pid->cache->flag & PTCACHE_BAKED)) { CLOG_ERROR(&LOG, "No matching files found for baked point cache in '%s'", path); return false; }
+  const auto rename_frame = [&](int frame, const char *from, const char *to) {
+    STRNCPY(pid->cache->name, from);
+    if (ptcache_filepath(pid, old_path_full, frame, true, true) <= 0) { errno = EINVAL; return -1; }
+    STRNCPY(pid->cache->name, to);
+    if (ptcache_filepath(pid, new_path_full, frame, true, true) <= 0) { errno = EINVAL; return -1; }
+    errno = 0;
+    const int result = BLI_rename(old_path_full, new_path_full);
+    if (result != 0 && errno == 0) errno = EIO;
+    return result;
+  };
+  size_t moved = 0;
+  for (; moved < frames.size(); moved++) {
+    if (rename_frame(frames[moved], name_src, name_dst) != 0) {
+      CLOG_ERROR(&LOG, "Cannot rename point cache '%s' to '%s': %s", old_path_full, new_path_full, std::strerror(errno));
+      break;
+    }
+  }
+  if (moved != frames.size()) {
+    while (moved > 0) {
+      if (rename_frame(frames[--moved], name_dst, name_src) != 0) {
+        CLOG_ERROR(&LOG, "Cannot restore point-cache file '%s' to '%s': %s", old_path_full, new_path_full, std::strerror(errno));
+        pid->cache->flag &= ~PTCACHE_BAKED;
+        pid->cache->flag |= PTCACHE_OUTDATED | PTCACHE_FLAG_INFO_DIRTY;
+      }
+    }
+    return false;
+  }
+  return true;
 }
 
 void BKE_ptcache_load_external(PTCacheID *pid)