fix(vfs): resolve two critical VFS bugs causing directory listing corruption

Bug 1: verbCountsByType optimization skipping requested verb types
- After restart, stale statistics could cause VerbType.Contains to be skipped
- readdir() would return empty/incomplete results
- Fixed by never skipping verb types explicitly requested in filter
- Added fast path for sourceId + verbType combo (common VFS pattern)
- Save statistics on first entity of each type (not just every 100th)

Bug 2: UnifiedCache not invalidated on path deletion
- rmdir() cleared local caches but NOT the global UnifiedCache
- When folder recreated, resolve() returned stale entity ID
- Caused "Source entity not found" errors
- Fixed by adding deleteByPrefix() to UnifiedCache
- Fixed invalidatePath() to also clear UnifiedCache entries

Files modified:
- src/storage/baseStorage.ts (verbCountsByType fix + fast path)
- src/utils/unifiedCache.ts (deleteByPrefix method)
- src/vfs/PathResolver.ts (cache invalidation fix)

Tests added:
- tests/unit/storage/vfs-mkdir-bug.test.ts (7 tests)

Reported by: Soulcraft Workshop team

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/storage/baseStorage.ts

@@ -1582,6 +1582,52 @@ export abstract class BaseStorage extends BaseStorageAdapter {
           nextCursor
         }
       }
+
+      // v6.2.9: Fast path for SINGLE sourceId + verbType combo (common VFS pattern)
+      // This avoids the slow type-iteration fallback for VFS operations
+      // NOTE: Only use fast path for single sourceId to avoid incomplete results
+      const isSingleSourceId = options.filter.sourceId &&
+        !Array.isArray(options.filter.sourceId)
+      if (
+        isSingleSourceId &&
+        options.filter.verbType &&
+        !options.filter.targetId &&
+        !options.filter.service &&
+        !options.filter.metadata
+      ) {
+        const sourceId = options.filter.sourceId as string
+        const verbTypes = Array.isArray(options.filter.verbType)
+          ? options.filter.verbType
+          : [options.filter.verbType]
+
+        prodLog.debug(`[BaseStorage] getVerbs: Using fast path for sourceId=${sourceId}, verbTypes=${verbTypes.join(',')}`)
+
+        // Get verbs by source (uses GraphAdjacencyIndex if available)
+        const verbsBySource = await this.getVerbsBySource_internal(sourceId)
+
+        // Filter by verbType in memory (fast - usually small number of verbs per source)
+        const filtered = verbsBySource.filter(v => verbTypes.includes(v.verb))
+
+        // Apply pagination
+        const paginatedVerbs = filtered.slice(offset, offset + limit)
+        const hasMore = offset + limit < filtered.length
+
+        // Set next cursor if there are more items
+        let nextCursor: string | undefined = undefined
+        if (hasMore && paginatedVerbs.length > 0) {
+          const lastItem = paginatedVerbs[paginatedVerbs.length - 1]
+          nextCursor = lastItem.id
+        }
+
+        prodLog.debug(`[BaseStorage] getVerbs: Fast path returned ${filtered.length} verbs (${paginatedVerbs.length} after pagination)`)
+
+        return {
+          items: paginatedVerbs,
+          totalCount: filtered.length,
+          hasMore,
+          nextCursor
+        }
+      }
     }
 
     // For more complex filtering or no filtering, use a paginated approach
@@ -1656,15 +1702,39 @@ export abstract class BaseStorage extends BaseStorageAdapter {
       const totalVerbCountFromArray = this.verbCountsByType.reduce((sum, c) => sum + c, 0)
       const useOptimization = totalVerbCountFromArray > 0
 
+      // v6.2.9 BUG FIX: Pre-compute requested verb types to avoid skipping them
+      // When a specific verbType filter is provided, we MUST check that type
+      // even if verbCountsByType shows 0 (counts can be stale after restart)
+      const requestedVerbTypes = options?.filter?.verbType
+      const requestedVerbTypesSet = requestedVerbTypes
+        ? new Set(Array.isArray(requestedVerbTypes) ? requestedVerbTypes : [requestedVerbTypes])
+        : null
+
       // Iterate through all 127 verb types (Stage 3 CANONICAL) with early termination
       // OPTIMIZATION: Skip types with zero count (only if counts are reliable)
       for (let i = 0; i < VERB_TYPE_COUNT && collectedVerbs.length < targetCount; i++) {
-        // Skip empty types for performance (but only if optimization is enabled)
-        if (useOptimization && this.verbCountsByType[i] === 0) {
+        const type = TypeUtils.getVerbFromIndex(i)
+
+        // v6.2.9 FIX: Never skip a type that's explicitly requested in the filter
+        // This fixes VFS bug where Contains relationships were skipped after restart
+        // when verbCountsByType[Contains] was 0 due to stale statistics
+        const isRequestedType = requestedVerbTypesSet?.has(type) ?? false
+        const countIsZero = this.verbCountsByType[i] === 0
+
+        // Skip empty types for performance (but only if optimization is enabled AND not requested)
+        if (useOptimization && countIsZero && !isRequestedType) {
           continue
         }
 
-        const type = TypeUtils.getVerbFromIndex(i)
+        // v6.2.9: Log when we DON'T skip a requested type that would have been skipped
+        // This helps diagnose stale statistics issues in production
+        if (useOptimization && countIsZero && isRequestedType) {
+          prodLog.debug(
+            `[BaseStorage] getVerbs: NOT skipping type=${type} despite count=0 (type was explicitly requested). ` +
+            `Statistics may be stale - consider running rebuildTypeCounts().`
+          )
+        }
+
         try {
           const verbsOfType = await this.getVerbsByType_internal(type)
 
@@ -2650,8 +2720,11 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     // COW-aware write (v5.0.1): Use COW helper for branch isolation
     await this.writeObjectToBranch(path, noun)
 
-    // Periodically save statistics (every 100 saves)
-    if (this.nounCountsByType[typeIndex] % 100 === 0) {
+    // Periodically save statistics
+    // v6.2.9: Also save on first noun of each type to ensure low-count types are tracked
+    const shouldSave = this.nounCountsByType[typeIndex] === 1 ||  // First noun of type
+                       this.nounCountsByType[typeIndex] % 100 === 0  // Every 100th
+    if (shouldSave) {
       await this.saveTypeStatistics()
     }
   }
@@ -2773,7 +2846,11 @@ export abstract class BaseStorage extends BaseStorageAdapter {
     }
 
     // Periodically save statistics
-    if (this.verbCountsByType[typeIndex] % 100 === 0) {
+    // v6.2.9: Also save on first verb of each type to ensure low-count types are tracked
+    // This prevents stale statistics after restart for types with < 100 verbs (common for VFS)
+    const shouldSave = this.verbCountsByType[typeIndex] === 1 ||  // First verb of type
+                       this.verbCountsByType[typeIndex] % 100 === 0  // Every 100th
+    if (shouldSave) {
       await this.saveTypeStatistics()
     }
   }

src/utils/unifiedCache.ts

@@ -415,6 +415,24 @@ export class UnifiedCache {
     return false
   }
 
+  /**
+   * Delete all items with keys starting with the given prefix
+   * v6.2.9: Added for VFS cache invalidation (fixes stale parent ID bug)
+   * @param prefix - The key prefix to match
+   * @returns Number of items deleted
+   */
+  deleteByPrefix(prefix: string): number {
+    let deleted = 0
+    for (const [key, item] of this.cache) {
+      if (key.startsWith(prefix)) {
+        this.currentSize -= item.size
+        this.cache.delete(key)
+        deleted++
+      }
+    }
+    return deleted
+  }
+
   /**
    * Clear cache or specific type
    */

src/vfs/PathResolver.ts

@@ -345,30 +345,44 @@ export class PathResolver {
 
   /**
    * Invalidate cache entries for a path and its children
+   * v6.2.9 FIX: Also invalidates UnifiedCache to prevent stale entity IDs
+   * This fixes the "Source entity not found" bug after delete+recreate operations
    */
   invalidatePath(path: string, recursive = false): void {
     const normalizedPath = this.normalizePath(path)
 
-    // Remove from all caches
+    // v6.2.9 FIX: Clear parent cache BEFORE deleting from pathCache
+    // (we need the entityId from the cache entry)
+    const cached = this.pathCache.get(normalizedPath)
+    if (cached) {
+      this.parentCache.delete(cached.entityId)
+    }
+
+    // Remove from local caches
     this.pathCache.delete(normalizedPath)
     this.hotPaths.delete(normalizedPath)
 
+    // v6.2.9 CRITICAL FIX: Also invalidate UnifiedCache (global LRU cache)
+    // This was missing before, causing stale entity IDs to be returned after delete
+    const cacheKey = `vfs:path:${normalizedPath}`
+    getGlobalCache().delete(cacheKey)
+
     if (recursive) {
       // Remove all paths that start with this path
       const prefix = normalizedPath.endsWith('/') ? normalizedPath : normalizedPath + '/'
 
-      for (const [cachedPath] of this.pathCache) {
+      for (const [cachedPath, entry] of this.pathCache) {
         if (cachedPath.startsWith(prefix)) {
           this.pathCache.delete(cachedPath)
           this.hotPaths.delete(cachedPath)
+          // v6.2.9: Also clear parent cache for this entry
+          this.parentCache.delete(entry.entityId)
         }
       }
-    }
 
-    // Clear parent cache for the entity
-    const cached = this.pathCache.get(normalizedPath)
-    if (cached) {
-      this.parentCache.delete(cached.entityId)
+      // v6.2.9 CRITICAL FIX: Also invalidate UnifiedCache entries with this prefix
+      const globalCachePrefix = `vfs:path:${prefix}`
+      getGlobalCache().deleteByPrefix(globalCachePrefix)
     }
   }