refactor(gpu): move SamplerCache impl to .cc, expose single entry point

get_or_create() and clear() moved out of the header-only class.
SamplerSpec and presets remain inline (trivial, no deps).

handoff(Gemini): sampler_cache split into .h/.cc, sampler_cache.cc added to COMMON_GPU_EFFECTS.

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

2 files changed, 36 insertions, 27 deletions

diff --git a/src/gpu/sampler_cache.cc b/src/gpu/sampler_cache.cc
new file mode 100644
index 0000000..c61c232
--- /dev/null
+++ b/src/gpu/sampler_cache.cc
@@ -0,0 +1,32 @@
+// Sampler cache implementation
+// See sampler_cache.h
+#include "gpu/sampler_cache.h"
+
+#include "platform/platform.h"
+#include "util/fatal_error.h"
+
+WGPUSampler SamplerCache::get_or_create(WGPUDevice device,
+                                        const SamplerSpec& spec) {
+  HEADLESS_RETURN_VAL_IF_NULL(device, nullptr);
+
+  auto it = cache_.find(spec);
+  if (it != cache_.end())
+    return it->second;
+
+  WGPUSamplerDescriptor desc{};
+  desc.addressModeU = spec.u;
+  desc.addressModeV = spec.v;
+  desc.magFilter = spec.mag;
+  desc.minFilter = spec.min;
+  desc.maxAnisotropy = spec.anisotropy;
+  WGPUSampler sampler = wgpuDeviceCreateSampler(device, &desc);
+  cache_[spec] = sampler;
+  return sampler;
+}
+
+void SamplerCache::clear() {
+  for (auto& pair : cache_) {
+    wgpuSamplerRelease(pair.second);
+  }
+  cache_.clear();
+}
diff --git a/src/gpu/sampler_cache.h b/src/gpu/sampler_cache.h
index 7d88109..0a2afa0 100644
--- a/src/gpu/sampler_cache.h
+++ b/src/gpu/sampler_cache.h
@@ -1,4 +1,5 @@
-// Sampler cache - deduplicates samplers across effects
+// Sampler cache - deduplicates WGPUSampler objects across effects
+// Single entry point: SamplerCache::Get().get_or_create(device, spec)
 #pragma once
 #include <map>
 
@@ -9,7 +10,6 @@ struct WGPUSamplerImpl;
 typedef struct WGPUSamplerImpl* WGPUSampler;
 
 #include "platform/platform.h"
-#include "util/fatal_error.h"
 
 struct SamplerSpec {
   WGPUAddressMode u, v;
@@ -39,24 +39,8 @@ class SamplerCache {
     return instance;
   }
 
-  WGPUSampler get_or_create(WGPUDevice device, const SamplerSpec& spec) {
-    // Headless mode: skip sampler creation (compiled out in STRIP_ALL)
-    HEADLESS_RETURN_VAL_IF_NULL(device, nullptr);
-
-    auto it = cache_.find(spec);
-    if (it != cache_.end())
-      return it->second;
-
-    WGPUSamplerDescriptor desc{};
-    desc.addressModeU = spec.u;
-    desc.addressModeV = spec.v;
-    desc.magFilter = spec.mag;
-    desc.minFilter = spec.min;
-    desc.maxAnisotropy = spec.anisotropy;
-    WGPUSampler sampler = wgpuDeviceCreateSampler(device, &desc);
-    cache_[spec] = sampler;
-    return sampler;
-  }
+  WGPUSampler get_or_create(WGPUDevice device, const SamplerSpec& spec);
+  void clear();
 
   // Common presets
   static SamplerSpec linear() {
@@ -67,11 +51,4 @@ class SamplerCache {
     return {WGPUAddressMode_ClampToEdge, WGPUAddressMode_ClampToEdge,
             WGPUFilterMode_Linear, WGPUFilterMode_Linear, 1};
   }
-
-  void clear() {
-    for (auto& pair : cache_) {
-      wgpuSamplerRelease(pair.second);
-    }
-    cache_.clear();
-  }
 };