perf(storage): simplify cloud adapters to always-on write buffering

Removes dynamic high-volume mode switching complexity from all cloud
storage adapters (GCS, S3, R2, Azure). Write buffering is now always
enabled for consistent, predictable performance.

Changes:
- Remove highVolumeMode, lastVolumeCheck, volumeCheckInterval properties
- Remove checkVolumeMode() methods (~100 lines in S3 alone)
- Remove BRAINY_FORCE_HIGH_VOLUME env var checks
- Always use write buffer when available
- Preserve v6.2.6 cache-before-buffer fix for consistency

Benefits:
- Consistent behavior regardless of load
- Predictable performance characteristics
- -204 lines of code complexity
- Cloud storage always benefits from batching

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

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

src/storage/adapters/r2Storage.ts

@@ -112,11 +112,8 @@ export class R2Storage extends BaseStorage {
   // Request coalescer for deduplication
   private requestCoalescer: RequestCoalescer | null = null
 
-  // High-volume mode detection (R2-specific thresholds)
-  private highVolumeMode = false
-  private lastVolumeCheck = 0
-  private volumeCheckInterval = 800  // Check more frequently on R2
-  private forceHighVolumeMode = false
+  // v6.2.7: Write buffering always enabled for consistent performance
+  // Removes dynamic mode switching complexity - cloud storage always benefits from batching
 
   // Multi-level cache manager for efficient data access
   private nounCacheManager: CacheManager<HNSWNode>
@@ -171,12 +168,7 @@ export class R2Storage extends BaseStorage {
     })
     this.verbCacheManager = new CacheManager<Edge>(options.cacheConfig)
 
-    // Check for high-volume mode override
-    if (typeof process !== 'undefined' && process.env?.BRAINY_FORCE_HIGH_VOLUME === 'true') {
-      this.forceHighVolumeMode = true
-      this.highVolumeMode = true
-      prodLog.info('🚀 R2: High-volume mode FORCED via environment variable')
-    }
+    // v6.2.7: Write buffering always enabled - no env var check needed
   }
 
   /**
@@ -417,32 +409,7 @@ export class R2Storage extends BaseStorage {
     }
   }
 
-  /**
-   * Check if high-volume mode should be enabled
-   */
-  private checkVolumeMode(): void {
-    if (this.forceHighVolumeMode) {
-      return
-    }
-
-    const now = Date.now()
-    if (now - this.lastVolumeCheck < this.volumeCheckInterval) {
-      return
-    }
-
-    this.lastVolumeCheck = now
-
-    // R2 threshold: enable at 15 pending operations (lower than S3/GCS)
-    const shouldEnable = this.pendingOperations > 15
-
-    if (shouldEnable && !this.highVolumeMode) {
-      this.highVolumeMode = true
-      prodLog.info('🚀 R2: High-volume mode ENABLED (pending:', this.pendingOperations, ')')
-    } else if (!shouldEnable && this.highVolumeMode && !this.forceHighVolumeMode) {
-      this.highVolumeMode = false
-      prodLog.info('🐌 R2: High-volume mode DISABLED (pending:', this.pendingOperations, ')')
-    }
-  }
+  // v6.2.7: Removed checkVolumeMode() - write buffering always enabled for cloud storage
 
   /**
    * Flush noun buffer to R2
@@ -477,18 +444,16 @@ export class R2Storage extends BaseStorage {
 
   /**
    * Save a node to storage
+   * v6.2.7: Always uses write buffer for consistent performance
    */
   protected async saveNode(node: HNSWNode): Promise<void> {
     await this.ensureInitialized()
 
-    this.checkVolumeMode()
-
-    // Use write buffer in high-volume mode
-    if (this.highVolumeMode && this.nounWriteBuffer) {
+    // v6.2.7: Always use write buffer - cloud storage benefits from batching
+    if (this.nounWriteBuffer) {
       this.logger.trace(`📝 BUFFERING: Adding noun ${node.id} to write buffer`)
 
-      // v6.2.6: CRITICAL FIX - Populate cache BEFORE buffering for read-after-write consistency
-      // Without this, add() returns but relate() can't find the entity (cloud storage production bug)
+      // v6.2.6: Populate cache BEFORE buffering for read-after-write consistency
       if (node.vector && Array.isArray(node.vector) && node.vector.length > 0) {
         this.nounCacheManager.set(node.id, node)
       }
@@ -497,7 +462,7 @@ export class R2Storage extends BaseStorage {
       return
     }
 
-    // Direct write in normal mode
+    // Fallback to direct write if buffer not initialized (shouldn't happen after init)
     await this.saveNodeDirect(node)
   }
 
@@ -761,18 +726,23 @@ export class R2Storage extends BaseStorage {
 
   // Verb storage methods (similar to noun methods - implementing key methods for space)
 
+  /**
+   * Save an edge to storage
+   * v6.2.7: Always uses write buffer for consistent performance
+   */
   protected async saveEdge(edge: Edge): Promise<void> {
     await this.ensureInitialized()
-    this.checkVolumeMode()
 
-    if (this.highVolumeMode && this.verbWriteBuffer) {
-      // v6.2.6: CRITICAL FIX - Populate cache BEFORE buffering for read-after-write consistency
+    // v6.2.7: Always use write buffer - cloud storage benefits from batching
+    if (this.verbWriteBuffer) {
+      // v6.2.6: Populate cache BEFORE buffering for read-after-write consistency
       this.verbCacheManager.set(edge.id, edge)
 
       await this.verbWriteBuffer.add(edge.id, edge)
       return
     }
 
+    // Fallback to direct write if buffer not initialized (shouldn't happen after init)
     await this.saveEdgeDirect(edge)
   }