Managing Metal4 Resources

---
name: managing-metal4-resources
description: ALWAYS use when working with Metal 4 resources — buffer / texture / heap creation, storage modes, `MTLResidencySet` management, heap aliasing, purgeable state, texture view pools, GPU lossless compression, and deferred destruction. Trigger for MTLBuffer, MTLTexture, MTLHeap, MTLResidencySet, addAllocation, requestResidency, useResidencySet, addResidencySet, MTLStorageMode*, MTLPurgeableState, MTLTextureViewPool, MTLResourceViewPool, newTextureViewWithPixelFormat:, copyFromBuffer:toTexture:, "GPU fault on resource", "non-resident resource", heap aliasing. Do NOT trigger for TBDR architecture or Metal 3 → Metal 4 namespace tables — use `translating-to-metal4-api`. Barrier visibility / `MTL4VisibilityOption*` / render-pass transition barriers — use `managing-metal4-synchronization`. `CAMetalLayer.residencySet` — use `presenting-metal-drawables`. `NS::SharedPtr` / autorelease pool / ARC bridging — use `managing-metal-cpp-lifetimes`.
---

# Metal 4 Resources

## Overview

Metal 4 requires explicit residency management via `MTLResidencySet`, removes managed storage mode, and uses GPU addresses for resource binding. Command buffers do NOT retain resources — you must manage lifetimes. All Apple Silicon uses unified memory (CPU and GPU share the same physical memory pool) and Tile-Based Deferred Rendering (TBDR).

## Ownership

**Owns:**
- Buffer / texture / heap creation, storage-mode selection
- General `MTLResidencySet` semantics — kernel/userspace, attachment levels, validation rules, deferred destruction
- Heap allocation and aliasing patterns
- Purgeable state, texture view pools, view reinterpretation
- GPU lossless compression rules
- Deferred destruction pattern (frame-delayed release queue)

**Doesn't own:**
- TBDR architecture → `translating-to-metal4-api/references/tbdr-architecture.md`
- Drawable-owned `CAMetalLayer.residencySet` (read-only specialization) → `presenting-metal-drawables`
- Barrier visibility options for aliased resources (`MTL4VisibilityOptions`) → `managing-metal4-synchronization`