refactor: unify runner lifecycles and weight residency (#1940)

include/stable-diffusion.h

@@ -229,9 +229,8 @@ typedef struct {
     bool vae_conv_direct;
     bool force_sdxl_vae_conv_scale;
     enum sd_vae_format_t vae_format;
-    const char* max_vram;  // GiB budget or backend assignment spec for graph-cut segmented param offload (0 = disabled, -1 = auto)
-    bool stream_layers;  // Enable residency+prefetch streaming on top of --max-vram (no effect without --max-vram)
-    bool disable_prefetch;  // Disable asynchronous layer prefetch while retaining synchronous stream_layers behavior
+    const char* max_vram;  // Optional per-device GiB budget for managed weights and runner buffers; 0 uses live free VRAM without an explicit budget
+    bool disable_prefetch;  // Disable asynchronous next-segment weight prefetch
     bool eager_load;  // Load all params into the params backend at model-load time instead of lazily on first use
     const char* backend;
     const char* params_backend;
@@ -239,6 +238,7 @@ typedef struct {
     bool auto_fit;
     const char* rpc_servers;
     const char* model_args;
+    bool disable_segmented_compute;  // Force monolithic graph execution even when automatic graph cutting would fit memory better
 } sd_ctx_params_t;
 
 typedef struct {