cvkg_render_gpu/

renderer.rs

//! The main SurtrRenderer struct and core frame lifecycle.
use crate::draw::{parse_svg_animations, usvg_to_lyon};
use crate::heim::SundrPacker;
use crate::kvasir;
use crate::types::*;
use crate::vertex::*;
use crate::{
    WGSL_BIFROST, WGSL_BLOOM, WGSL_COLOR_BLIND, WGSL_COMMON, WGSL_MATERIAL_GLASS,
    WGSL_MATERIAL_OPAQUE, WGSL_SHAPES, WGSL_TONEMAP,
};
use bytemuck;
use cvkg_core::Rect;
use cvkg_core::Renderer;
use cvkg_core::{ColorTheme, SceneUniforms};
use lru::LruCache;
use lyon::tessellation::{
    BuffersBuilder, FillOptions, FillTessellator, StrokeOptions, StrokeTessellator, VertexBuffers,
};
use std::collections::VecDeque;
use std::num::NonZeroUsize;
use std::sync::Arc;

/// SurtrRenderer implements the high-performance GPU backend.
pub struct SurtrRenderer {
    pub(crate) instance: Arc<wgpu::Instance>,
    pub(crate) adapter: Arc<wgpu::Adapter>,
    pub(crate) device: Arc<wgpu::Device>,
    pub(crate) queue: Arc<wgpu::Queue>,

    // Kvasir resource registry — tracks GPU resource lifetimes
    pub(crate) registry: crate::kvasir::registry::ResourceRegistry,

    pub(crate) active_offscreens: Vec<crate::types::OffscreenEffectConfig>,
    pub(crate) effect_pipelines: std::collections::HashMap<String, wgpu::RenderPipeline>,
    pub(crate) effect_params_buffer: wgpu::Buffer,
    pub(crate) effect_params_bind_group: wgpu::BindGroup,
    pub(crate) linear_sampler: wgpu::Sampler,
    // AI Generator Channel
    pub ai_material_rx: Option<
        std::sync::mpsc::Receiver<
            Result<crate::material::CompiledMaterial, crate::ai::GeneratorError>,
        >,
    >,

    // Multi-Window Surface Management
    pub(crate) surfaces: std::collections::HashMap<winit::window::WindowId, SurfaceContext>,
    pub(crate) current_window: Option<winit::window::WindowId>,
    pub headless_context: Option<HeadlessContext>,

    // Mega-Heim (Shared across all windows)
    pub(crate) text_engine: cvkg_runic_text::RunicTextEngine,
    pub(crate) mega_heim_tex: wgpu::Texture,
    pub(crate) mega_heim_bind_group: wgpu::BindGroup,
    pub(crate) text_cache: LruCache<u64, (Rect, f32, f32, f32, f32)>,
    pub(crate) shaped_text_cache:
        std::collections::HashMap<(String, u32), cvkg_runic_text::ShapedText>,
    pub(crate) heim_packer: SundrPacker,
    pub(crate) image_uv_registry: LruCache<String, Rect>,
    pub(crate) texture_registry: LruCache<String, u32>,
    pub(crate) texture_views: Vec<wgpu::TextureView>,
    pub(crate) dummy_sampler: wgpu::Sampler,
    pub(crate) svg_cache: LruCache<String, SvgModel>,
    /// Parsed SVG trees for serialization and filter application.
    pub(crate) svg_trees: LruCache<String, usvg::Tree>,
    /// SVG filter evaluation engine.
    pub(crate) filter_engine: Option<cvkg_svg_filters::FilterEngine>,
    /// Pending filter batches accumulated during tessellation.
    pub(crate) filter_batches: Vec<cvkg_svg_filters::FilterNode>,

    // Niflheim Resources (Shared)
    pub(crate) dummy_texture_bind_group: wgpu::BindGroup,
    pub(crate) dummy_env_bind_group: wgpu::BindGroup,
    pub(crate) texture_bind_group_layout: wgpu::BindGroupLayout,
    pub(crate) texture_bind_groups: Vec<wgpu::BindGroup>,
    pub(crate) shared_elements: LruCache<String, cvkg_core::Rect>,

    // The Forge's Anvil (GPU Buffers)
    pub(crate) vertex_buffer: wgpu::Buffer,
    pub(crate) index_buffer: wgpu::Buffer,
    pub(crate) instance_buffer: wgpu::Buffer,
    pub(crate) vertices: Vec<Vertex>,
    pub(crate) indices: Vec<u32>,
    pub(crate) instance_data: Vec<InstanceData>,
    pub(crate) staging_belt: wgpu::util::StagingBelt,
    pub(crate) staging_command_buffers: Vec<wgpu::CommandBuffer>,
    pub(crate) draw_calls: Vec<DrawCall>,
    pub(crate) current_texture_id: Option<u32>,

    // Opacity & Clip Stacks
    pub(crate) opacity_stack: Vec<f32>,
    pub(crate) clip_stack: Vec<Rect>,
    pub(crate) slice_stack: Vec<(f32, f32)>,
    pub(crate) shadow_stack: Vec<ShadowState>,

    // The Forge's Heart (Shared Berserker State)
    pub(crate) theme_buffer: wgpu::Buffer,
    pub(crate) scene_buffer: wgpu::Buffer,
    pub(crate) berserker_bind_group: wgpu::BindGroup,
    pub(crate) berserker_bind_group_layout: wgpu::BindGroupLayout,
    pub(crate) start_time: std::time::Instant,
    pub(crate) current_theme: ColorTheme,
    pub(crate) current_scene: SceneUniforms,
    pub(crate) current_z: f32,

    // Muspelheim Pipelines (Shared)
    pub(crate) pipeline: wgpu::RenderPipeline,
    /// Specialized opaque/2D material pipeline (modes 0-20 excluding 7,13-15,18,21).
    pub(crate) opaque_pipeline: wgpu::RenderPipeline,
    /// Non-multisampled pipeline used specifically to draw UI overlays.
    /// Drawn with sample count 1 and no depth testing/depth stencil attachment.
    pub(crate) ui_pipeline: wgpu::RenderPipeline,
    /// Specialized glass material pipeline (mode 7 only, ~150 lines of complex math).
    pub(crate) glass_pipeline: wgpu::RenderPipeline,
    pub(crate) background_pipeline: wgpu::RenderPipeline,
    pub(crate) bloom_extract_pipeline: wgpu::RenderPipeline,
    /// Identity copy pipeline for Pass 2 backdrop blur (all pixels, no luminance gate).
    pub(crate) copy_pipeline: wgpu::RenderPipeline,
    pub(crate) composite_pipeline: wgpu::RenderPipeline,
    /// Color blindness simulation pipeline (fullscreen triangle).
    pub(crate) color_blind_pipeline: wgpu::RenderPipeline,
    /// Volumetric raymarching pipeline (fullscreen triangle with SDF raymarch).
    pub(crate) volumetric_pipeline: wgpu::RenderPipeline,
    /// Volumetric bind group layout for scene uniforms (time/resolution/light).
    pub(crate) volumetric_bind_group_layout: wgpu::BindGroupLayout,
    /// Persistent uniform buffer for volumetric data (updated each frame).
    pub(crate) volumetric_uniform_buffer: wgpu::Buffer,
    /// Kawase blur pyramid downsample pipeline (separate shader module).
    pub(crate) kawase_down_pipeline: wgpu::RenderPipeline,
    /// Kawase blur pyramid upsample pipeline (separate shader module).
    pub(crate) kawase_up_pipeline: wgpu::RenderPipeline,
    /// Kawase blur bind group layout (uniform + texture + sampler).
    pub(crate) kawase_bind_group_layout: wgpu::BindGroupLayout,
    /// Persistent uniform buffer for Kawase blur operations (avoids per-frame allocation).
    pub(crate) kawase_uniform: wgpu::Buffer,
    /// Environment bind group layout (texture + sampler).
    pub(crate) env_bind_group_layout: wgpu::BindGroupLayout,

    // Telemetry
    pub telemetry: cvkg_core::TelemetryData,

    /// Configuration for render-loop frame timing and degradation strategies.
    pub frame_budget: cvkg_core::FrameBudget,
    /// Staging buffer for windowed frame capture.
    pub(crate) capture_staging_buffer: Option<wgpu::Buffer>,
    /// Instant at the start of the last redraw, used for measuring frame timings.
    pub last_redraw_start: std::time::Instant,
    /// Instant at the start of the last frame, used for frame_time_ms calculation.
    pub last_frame_start: std::time::Instant,

    // VRAM Tracking (Bytes)
    pub(crate) vram_buffers_bytes: u64,
    pub(crate) vram_textures_bytes: u64,

    // Debugging
    pub(crate) _debug_layout: bool,

    // Transform Stack — stores full affine matrices for correct SVG transform composition.
    pub(crate) transform_stack: Vec<glam::Mat3>,
    /// Whether a redraw has been requested for the next frame.
    pub redraw_requested: bool,
    /// Cursor for compositor draw call submission tracking.
    pub(crate) compositor_index_cursor: u32,

    /// Bloom post-processing enabled flag.
    pub bloom_enabled: bool,
    /// Dynamic toggle to enable or disable the volumetric raymarching pass, which handles fog and light shaft simulations.
    pub volumetric_enabled: bool,
    /// Color blindness bind group layout (texture + sampler + uniform).
    pub(crate) color_blind_bind_group_layout: wgpu::BindGroupLayout,
    /// Color blindness uniform buffer (updated each frame when mode changes).
    pub(crate) color_blind_uniform_buffer: wgpu::Buffer,
    /// Color blindness simulation mode (Normal = disabled).
    pub color_blind_mode: crate::color_blindness::ColorBlindMode,
    /// Color blindness effect intensity (0.0–1.0).
    pub color_blind_intensity: f32,
    /// Sampler for the color blindness pass (reused from main pipeline).
    pub(crate) sampler: wgpu::Sampler,

    // Timestamp Queries (Norse: Skuld = future/time/debt)
    pub(crate) skuld_queries: Option<wgpu::QuerySet>,
    pub(crate) skuld_buffer: Option<wgpu::Buffer>,
    pub(crate) skuld_read_buffer: Option<wgpu::Buffer>,
    pub(crate) skuld_period: f32,
    pub last_gpu_time_ns: u64,

    // VDOM node stack for hierarchy tracking
    pub(crate) vnode_stack: Vec<(Rect, &'static str)>,

    /// Event handlers registered during render passes.
    /// Maps "event_type" -> list of handlers.
    pub(crate) event_handlers: std::collections::HashMap<
        String,
        Vec<std::sync::Arc<dyn Fn(cvkg_core::Event) + Send + Sync>>,
    >,

    /// Bind group layout for reading blur output in glass composite pass.
    pub(crate) glass_output_bind_group_layout: wgpu::BindGroupLayout,
    /// Current material state — draw calls are tagged with this material.
    pub(crate) current_draw_material: cvkg_core::DrawMaterial,

    /// Portal backdrop blur regions — collected during portal enter/exit
    /// Used for per-element isolated backdrop blur (Tahoe feature)
    pub(crate) portal_regions: std::collections::VecDeque<cvkg_core::Rect>,

    /// Cache of the compiled Kvasir render graph execution plan.
    /// Used to bypass graph rebuilding and topological sorting when configuration is unchanged.
    pub(crate) cached_graph_plan: Option<kvasir::graph_cache::CachedGraphPlan>,
    /// Memoization cache for frame-level render skipping.
    /// Tracks (id, data_hash) -> skip_render for deduplication.
    pub(crate) memo_cache: std::collections::HashMap<u64, u64>,
    /// Thread-safe bind group cache to avoid per-frame allocations during render passes.
    /// Maps a cache key representing texture/pass metadata to the pre-created wgpu::BindGroup.
    pub(crate) bind_group_cache: std::sync::Mutex<
        std::collections::HashMap<
            (crate::kvasir::resource::ResourceId, u32, bool),
            wgpu::BindGroup,
        >,
    >,
    /// Thread-safe texture view cache to avoid per-frame allocations of TextureViews.
    /// Maps (texture id, mip level) -> wgpu::TextureView.
    pub(crate) texture_view_cache: std::sync::Mutex<
        std::collections::HashMap<(crate::kvasir::resource::ResourceId, u32), wgpu::TextureView>,
    >,
}

#[cfg(target_arch = "wasm32")]
unsafe impl Send for SurtrRenderer {}
#[cfg(target_arch = "wasm32")]
unsafe impl Sync for SurtrRenderer {}

/// SVG tessellation parameters.
pub(crate) struct TessellateParams<'a> {
    fill_tessellator: &'a mut FillTessellator,
    stroke_tessellator: &'a mut StrokeTessellator,
    vertices: &'a mut Vec<Vertex>,
    indices: &'a mut Vec<u32>,
    parsed_animations: &'a [SvgAnimation],
    finalized_animations: &'a mut Vec<SvgAnimation>,
    paths: &'a mut Vec<crate::types::SvgPath>,
}

impl SurtrRenderer {
    /// Update cursor pointer uniforms for tactile hover shader interactions.
    ///
    /// # Contract
    /// - `mouse` represents logical window coordinates.
    /// - `velocity` is the change in logical coordinates per second.
    pub fn update_mouse(&mut self, mouse: [f32; 2], velocity: [f32; 2]) {
        self.current_scene.mouse = mouse;
        self.current_scene.mouse_velocity = velocity;
    }

    /// select_best_surface_format selects the highest precision/HDR texture format
    /// supported by the surface. Favors floating point HDR (Rgba16Float) or Display P3 wide gamut
    /// (Rgba8Unorm) over standard sRGB, falling back to sRGB/first option if not available.
    pub(crate) fn select_best_surface_format(
        formats: &[wgpu::TextureFormat],
    ) -> wgpu::TextureFormat {
        let preferred_formats = [
            wgpu::TextureFormat::Rgba16Float, // HDR10 / Rec. 2020 FP16
            wgpu::TextureFormat::Rgba8Unorm,  // Wide Color Display P3
            wgpu::TextureFormat::Bgra8UnormSrgb,
            wgpu::TextureFormat::Rgba8UnormSrgb,
        ];
        for preferred in &preferred_formats {
            if formats.contains(preferred) {
                return *preferred;
            }
        }
        formats[0]
    }

    /// forge — Initializes the Surtr GPU renderer from a winit window.
    ///
    /// This method performs the following:
    /// 1. Negotiates a wgpu surface and adapter.
    /// 2. Forges the Muspelheim multi-pass pipeline layouts.
    /// 3. Initializes the Berserker state buffers and texture registries.
    pub async fn forge(window: Arc<winit::window::Window>) -> Self {
        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
            backends: wgpu::Backends::all(),
            flags: wgpu::InstanceFlags::default(),
            backend_options: wgpu::BackendOptions::default(),
            display: None,
            memory_budget_thresholds: wgpu::MemoryBudgetThresholds::default(),
        });

        let surface = instance
            .create_surface(window.clone())
            .expect("Failed to create surface");

        // Request adapter with robust multi-stage fallback for Bumblebee/Optimus compatibility
        log::info!("[GPU] Requesting HighPerformance adapter...");

        let mut adapter = None;

        #[cfg(not(target_arch = "wasm32"))]
        if let Ok(filter) = std::env::var("WGPU_ADAPTER_NAME") {
            let adapters = instance.enumerate_adapters(wgpu::Backends::all()).await;
            log::info!("[GPU] Available adapters:");
            for a in &adapters {
                let info = a.get_info();
                log::info!(
                    "  - Name: '{}' | Driver: '{}' | Backend: {:?}",
                    info.name,
                    info.driver,
                    info.backend
                );
            }

            adapter = adapters.into_iter().find(|a| {
                let info = a.get_info();
                let match_found = info.name.to_lowercase().contains(&filter.to_lowercase())
                    || info.driver.to_lowercase().contains(&filter.to_lowercase());
                if match_found {
                    log::info!(
                        "[GPU] Manual selection match: {} | Driver: {}",
                        info.name,
                        info.driver
                    );
                }
                match_found
            });

            if adapter.is_some() {
                log::info!(
                    "[GPU] Forced adapter selection via WGPU_ADAPTER_NAME='{}'",
                    filter
                );
            } else {
                log::warn!(
                    "[GPU] WGPU_ADAPTER_NAME='{}' provided but no matching adapter found. Falling back...",
                    filter
                );
            }
        }

        if adapter.is_none() {
            adapter = instance
                .request_adapter(&wgpu::RequestAdapterOptions {
                    power_preference: wgpu::PowerPreference::HighPerformance,
                    compatible_surface: Some(&surface),
                    force_fallback_adapter: false,
                })
                .await
                .ok();
        }

        if adapter.is_none() {
            log::warn!(
                "[GPU] HighPerformance adapter failed (possible Bumblebee/Optimus), trying LowPower..."
            );
            adapter = instance
                .request_adapter(&wgpu::RequestAdapterOptions {
                    power_preference: wgpu::PowerPreference::LowPower,
                    compatible_surface: Some(&surface),
                    force_fallback_adapter: false,
                })
                .await
                .ok();
        }

        if adapter.is_none() {
            log::warn!("[GPU] Hardware adapters failed, trying Software fallback...");
            adapter = instance
                .request_adapter(&wgpu::RequestAdapterOptions {
                    power_preference: wgpu::PowerPreference::LowPower,
                    compatible_surface: Some(&surface),
                    force_fallback_adapter: true,
                })
                .await
                .ok();
        }

        let adapter = adapter.expect("Failed to find a suitable GPU for Surtr");
        let info = adapter.get_info();
        log::info!(
            "[GPU] Selected adapter: {} ({:?}) on backend: {:?}",
            info.name,
            info.device_type,
            info.backend
        );
        log::info!("[GPU] Driver info: {} - {}", info.driver, info.driver_info);
        let supports_timestamps = adapter.features().contains(wgpu::Features::TIMESTAMP_QUERY);
        #[cfg(not(target_arch = "wasm32"))]
        let mut required_features =
            wgpu::Features::SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING
                | wgpu::Features::TEXTURE_BINDING_ARRAY;

        #[cfg(target_arch = "wasm32")]
        let mut required_features = wgpu::Features::empty(); // Fallbacks for WebGL
        if supports_timestamps {
            required_features |= wgpu::Features::TIMESTAMP_QUERY;
        }
                // Enable validation layer in debug builds for better error reporting
        #[cfg(all(debug_assertions, not(target_arch = "wasm32")))]
        {
            log::info!("[GPU] Validation layer enabled (debug build)");
        }

        let (device, queue) = adapter
            .request_device(&wgpu::DeviceDescriptor {
                label: Some("Surtr Forge"),
                required_features,
                required_limits: wgpu::Limits {
                    max_bindings_per_bind_group: 256,
                    max_binding_array_elements_per_shader_stage: 256,
                    ..wgpu::Limits::default()
                },
                memory_hints: wgpu::MemoryHints::default(),
                experimental_features: wgpu::ExperimentalFeatures::disabled(),
                trace: wgpu::Trace::Off,
            })
            .await
            .expect("Failed to create Surtr device");

        let instance = Arc::new(instance);
        let adapter = Arc::new(adapter);

        device.on_uncaptured_error(Arc::new(|error| {
            log::error!(
                "[GPU] Uncaptured device error (Device Lost or Panic): {:?}",
                error
            );
            // In a full recovery scenario, we would signal the event loop to rebuild the GPU context
        }));

        let device = Arc::new(device);
        let queue = Arc::new(queue);

        let size = window.inner_size();
        // Ensure we have valid dimensions - Wayland may return 0 for not-yet-committed surfaces
        let width = if size.width > 0 { size.width } else { 1280 };
        let height = if size.height > 0 { size.height } else { 720 };
        let surface_caps = surface.get_capabilities(&adapter);
        let surface_format = if surface_caps.formats.is_empty() {
            log::error!("[GPU] CRITICAL: No compatible surface formats found for this adapter!");
            log::error!(
                "[GPU] Adapter: {} | Backend: {:?}",
                adapter.get_info().name,
                adapter.get_info().backend
            );
            // Fallback to a common format to avoid immediate panic, though configuration may still fail
            wgpu::TextureFormat::Rgba8UnormSrgb
        } else {
            surface_caps
                .formats
                .iter()
                .find(|f| f.is_srgb())
                .copied()
                .unwrap_or(surface_caps.formats[0])
        };

        // Dynamic capability selection for robust Wayland/X11 rendering
        let present_mode = if surface_caps
            .present_modes
            .contains(&wgpu::PresentMode::Mailbox)
        {
            wgpu::PresentMode::Mailbox
        } else {
            log::warn!("[GPU] Mailbox not supported, falling back to Fifo (V-Sync)");
            wgpu::PresentMode::Fifo
        };

        let alpha_mode = if surface_caps
            .alpha_modes
            .contains(&wgpu::CompositeAlphaMode::PostMultiplied)
        {
            wgpu::CompositeAlphaMode::PostMultiplied
        } else if surface_caps
            .alpha_modes
            .contains(&wgpu::CompositeAlphaMode::PreMultiplied)
        {
            wgpu::CompositeAlphaMode::PreMultiplied
        } else {
            surface_caps.alpha_modes[0]
        };

        log::info!(
            "[GPU] Configuring surface: {}x{} | {:?} | {:?}",
            width,
            height,
            present_mode,
            alpha_mode
        );

        let config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format: surface_format,
            width,
            height,
            present_mode,
            alpha_mode,
            view_formats: vec![],
            desired_maximum_frame_latency: 2,
        };
        surface.configure(&device, &config);
        log::info!("[GPU] Surface configuration successful.");

        let renderer = Self::forge_internal(
            instance,
            adapter,
            device,
            queue,
            Some((window, surface, config)),
            None,
        )
        .await;
        log::info!("[GPU] Forge internal complete.");
        renderer
    }

    /// Internal rendering pipeline constructor.
    /// This function spans ~600 lines because it is responsible for forging the entire wgpu state machine.
    ///
    /// ## Structure:
    /// 1. Formats & Timestamp query resolution buffers
    /// 2. Bind Group Layouts (Uniforms, Environment, Blur, Color Blindness)
    /// 3. Pipeline compilation (Opaque, Glass, Text, SVG paths)
    /// 4. Global Mega Atlas and Dummy Texture initialization
    /// 5. Staging belt & Telemetry scaffolding
    pub(crate) async fn forge_internal(
        instance: Arc<wgpu::Instance>,
        adapter: Arc<wgpu::Adapter>,
        device: Arc<wgpu::Device>,
        queue: Arc<wgpu::Queue>,
        surface_info: Option<(
            Arc<winit::window::Window>,
            wgpu::Surface<'static>,
            wgpu::SurfaceConfiguration,
        )>,
        headless_info: Option<(u32, u32, wgpu::TextureFormat)>,
    ) -> Self {
        let format = if let Some((_, _, ref config)) = surface_info {
            config.format
        } else if let Some((_, _, f)) = headless_info {
            f
        } else {
            wgpu::TextureFormat::Rgba8UnormSrgb
        };

        let supports_timestamps = adapter.features().contains(wgpu::Features::TIMESTAMP_QUERY);
        let skuld_period = queue.get_timestamp_period();
        let (skuld_queries, skuld_buffer, skuld_read_buffer) = if supports_timestamps {
            let q = device.create_query_set(&wgpu::QuerySetDescriptor {
                label: Some("Skuld Timestamp Queries"),
                count: 2,
                ty: wgpu::QueryType::Timestamp,
            });
            let b = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Skuld Query Buffer"),
                size: 16,
                usage: wgpu::BufferUsages::QUERY_RESOLVE | wgpu::BufferUsages::COPY_SRC,
                mapped_at_creation: false,
            });
            let rb = device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Skuld Read Buffer"),
                size: 16,
                usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
                mapped_at_creation: false,
            });
            (Some(q), Some(b), Some(rb))
        } else {
            (None, None, None)
        };

        // Dynamically compile material WGSL
        let materials_generated = crate::material::generate_builtins_wgsl();

        let wgsl_src = format!(
            "{}{}{}{}{}{}",
            WGSL_COMMON,
            WGSL_SHAPES,
            WGSL_BIFROST,
            WGSL_BLOOM,
            WGSL_COLOR_BLIND,
            materials_generated
        );
        let wgsl_opaque = format!(
            "{}{}{}{}{}{}",
            WGSL_COMMON,
            WGSL_MATERIAL_OPAQUE,
            WGSL_BIFROST,
            WGSL_BLOOM,
            WGSL_COLOR_BLIND,
            materials_generated
        );
        let wgsl_glass = format!(
            "{}{}{}{}{}{}",
            WGSL_COMMON,
            WGSL_MATERIAL_GLASS,
            WGSL_BIFROST,
            WGSL_BLOOM,
            WGSL_COLOR_BLIND,
            materials_generated
        );

        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Surtr Main Shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Owned(wgsl_src)),
        });

        // Niflheim Bind Group Layout (for textures/samplers)
        let texture_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            multisampled: false,
                            view_dimension: wgpu::TextureViewDimension::D2,
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        },
                        count: std::num::NonZeroU32::new(256),
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                ],
                label: Some("Niflheim Texture Bind Group Layout"),
            });

        // Environment Bind Group Layout (for blurred background / Bifrost)
        // Environment Bind Group Layout (for blurred background / Bifrost)
        let env_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Texture {
                            multisampled: false,
                            view_dimension: wgpu::TextureViewDimension::D2,
                            sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                        count: None,
                    },
                ],
                label: Some("Surtr Environment Bind Group Layout"),
            });

        let berserker_bind_group_layout =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStages::FRAGMENT,
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStages::FRAGMENT | wgpu::ShaderStages::VERTEX,
                        ty: wgpu::BindingType::Buffer {
                            ty: wgpu::BufferBindingType::Uniform,
                            has_dynamic_offset: false,
                            min_binding_size: None,
                        },
                        count: None,
                    },
                ],
                label: Some("Surtr Berserker Bind Group Layout"),
            });

        // Pipeline setup
        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Surtr Main Pipeline Layout"),
            bind_group_layouts: &[
                Some(&texture_bind_group_layout),
                Some(&env_bind_group_layout),
                Some(&berserker_bind_group_layout),
            ],
            immediate_size: 0,
        });

        // Specialized layout for post-processing (Bloom Extract, Blur) which only need Group 0 + Globals
        let post_process_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Muspelheim Post Process Layout"),
            bind_group_layouts: &[
                Some(&texture_bind_group_layout),
                Some(&env_bind_group_layout),
                Some(&berserker_bind_group_layout),
            ],
            immediate_size: 0,
        });

        // Specialized layout for composite (Blur + Scene)
        let composite_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Muspelheim Composite Layout"),
            bind_group_layouts: &[
                Some(&texture_bind_group_layout),
                Some(&env_bind_group_layout),
                Some(&berserker_bind_group_layout),
            ],
            immediate_size: 0,
        });

        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Surtr Main Pipeline"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: Some("vs_main"),
                buffers: &[Vertex::desc(), InstanceData::desc()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: Some(true),
                depth_compare: Some(wgpu::CompareFunction::LessEqual),
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: 4,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview_mask: None,
            cache: None,
        });

        let background_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Surtr Background Pipeline"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: Some("vs_fullscreen"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: Some("fs_background"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: Some(false),
                depth_compare: Some(wgpu::CompareFunction::Always),
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: 4,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview_mask: None,
            cache: None,
        });

        // ── Specialized Material Pipelines ─────────────────────────────────────
        let opaque_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Muspelheim Opaque"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Owned(wgsl_opaque)),
        });
        let glass_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Muspelheim Glass"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Owned(wgsl_glass)),
        });

        let opaque_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Muspelheim Opaque"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &opaque_shader,
                entry_point: Some("vs_main"),
                buffers: &[Vertex::desc(), InstanceData::desc()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &opaque_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: Some(wgpu::DepthStencilState {
                format: wgpu::TextureFormat::Depth32Float,
                depth_write_enabled: Some(true),
                depth_compare: Some(wgpu::CompareFunction::LessEqual),
                stencil: wgpu::StencilState::default(),
                bias: wgpu::DepthBiasState::default(),
            }),
            multisample: wgpu::MultisampleState {
                count: 4,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview_mask: None,
            cache: None,
        });
        let ui_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Muspelheim UI"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &opaque_shader,
                entry_point: Some("vs_main"),
                buffers: &[Vertex::desc(), InstanceData::desc()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &opaque_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview_mask: None,
            cache: None,
        });
        let glass_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Muspelheim Glass"),
            layout: Some(&pipeline_layout),
            vertex: wgpu::VertexState {
                module: &opaque_shader,
                entry_point: Some("vs_main"),
                buffers: &[Vertex::desc(), InstanceData::desc()],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &glass_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState::ALPHA_BLENDING),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState {
                count: 1,
                mask: !0,
                alpha_to_coverage_enabled: false,
            },
            multiview_mask: None,
            cache: None,
        });

        // Muspelheim Bloom Extract Pipeline
        let bloom_extract_pipeline =
            device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
                label: Some("Muspelheim Bloom Extract"),
                layout: Some(&post_process_layout),
                vertex: wgpu::VertexState {
                    module: &shader,
                    entry_point: Some("vs_fullscreen"),
                    buffers: &[],
                    compilation_options: wgpu::PipelineCompilationOptions::default(),
                },
                fragment: Some(wgpu::FragmentState {
                    module: &shader,
                    entry_point: Some("fs_bloom_extract"),
                    targets: &[Some(wgpu::ColorTargetState {
                        format,
                        blend: None,
                        write_mask: wgpu::ColorWrites::ALL,
                    })],
                    compilation_options: wgpu::PipelineCompilationOptions::default(),
                }),
                primitive: wgpu::PrimitiveState::default(),
                depth_stencil: None,
                multisample: wgpu::MultisampleState::default(),
                multiview_mask: None,
                cache: None,
            });

        // Muspelheim Copy Pipeline (identity copy for backdrop blur Pass 2)
        let copy_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Muspelheim Copy"),
            layout: Some(&post_process_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: Some("vs_fullscreen"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: Some("fs_copy"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // Kawase blur pyramid pipelines (separate shader module — conflicting bindings)
        // NOTE: Compiled separately because blur_pyramid.wgsl defines its own
        // @group(0) bindings (BlurUniforms + texture + sampler) that conflict
        // with the main WGSL_SRC pipeline layout.
        let kawase_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Kawase Blur Pyramid"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "shaders/blur_pyramid.wgsl"
            ))),
        });
        let kawase_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("Kawase Blur BGL"),
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(32),
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        view_dimension: wgpu::TextureViewDimension::D2,
                        multisampled: false,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
            ],
        });
        let kawase_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Kawase Pipeline Layout"),
            bind_group_layouts: &[Some(&kawase_bgl)],
            immediate_size: 0,
        });
        let kawase_down_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Kawase Downsample"),
            layout: Some(&kawase_layout),
            vertex: wgpu::VertexState {
                module: &kawase_shader,
                entry_point: Some("vs_blur"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &kawase_shader,
                entry_point: Some("fs_kawase_down"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });
        let kawase_up_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Kawase Upsample"),
            layout: Some(&kawase_layout),
            vertex: wgpu::VertexState {
                module: &kawase_shader,
                entry_point: Some("vs_blur"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &kawase_shader,
                entry_point: Some("fs_kawase_up"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // Muspelheim Composite Pipeline (additive blend onto screen)
        let composite_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Muspelheim Composite"),
            layout: Some(&composite_layout),
            vertex: wgpu::VertexState {
                module: &shader,
                entry_point: Some("vs_fullscreen"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &shader,
                entry_point: Some("fs_composite"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    // Additive blend: src + dst — glow lights up the scene
                    blend: Some(wgpu::BlendState {
                        color: wgpu::BlendComponent {
                            src_factor: wgpu::BlendFactor::One,
                            dst_factor: wgpu::BlendFactor::One,
                            operation: wgpu::BlendOperation::Add,
                        },
                        alpha: wgpu::BlendComponent {
                            src_factor: wgpu::BlendFactor::SrcAlpha,
                            dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
                            operation: wgpu::BlendOperation::Add,
                        },
                    }),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // Forge the Mega-Heim (4096x4096 RGBA for production batching)
        let mega_heim_tex = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Surtr Mega-Heim"),
            size: wgpu::Extent3d {
                width: 4096,
                height: 4096,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsages::TEXTURE_BINDING
                | wgpu::TextureUsages::COPY_DST
                | wgpu::TextureUsages::COPY_SRC,
            view_formats: &[],
        });
        let mega_heim_view_obj = mega_heim_tex.create_view(&wgpu::TextureViewDescriptor::default());
        let text_sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear, // Use linear for images
            min_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        // Forge the Niflheim Dummy Texture (1x1 White)
        let dummy_size = wgpu::Extent3d {
            width: 1,
            height: 1,
            depth_or_array_layers: 1,
        };
        let dummy_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Niflheim Dummy Texture"),
            size: dummy_size,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_DST,
            view_formats: &[],
        });
        queue.write_texture(
            wgpu::TexelCopyTextureInfo {
                texture: &dummy_texture,
                mip_level: 0,
                origin: wgpu::Origin3d::ZERO,
                aspect: wgpu::TextureAspect::All,
            },
            &[255, 255, 255, 255],
            wgpu::TexelCopyBufferLayout {
                offset: 0,
                bytes_per_row: Some(4),
                rows_per_image: Some(1),
            },
            dummy_size,
        );

        let dummy_view = dummy_texture.create_view(&wgpu::TextureViewDescriptor::default());
        let dummy_sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            address_mode_w: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Nearest,
            mipmap_filter: wgpu::MipmapFilterMode::Nearest,
            ..Default::default()
        });

        let mut texture_views_list: Vec<wgpu::TextureView> =
            (0..256).map(|_| dummy_view.clone()).collect();
        texture_views_list[0] = mega_heim_view_obj.clone();

        let views_refs: Vec<&wgpu::TextureView> = texture_views_list.iter().collect();
        let mega_heim_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureViewArray(&views_refs),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&text_sampler),
                },
            ],
            label: Some("Mega-Heim Bind Group"),
        });

        let dummy_views_refs: Vec<&wgpu::TextureView> = (0..256).map(|_| &dummy_view).collect();
        let dummy_texture_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureViewArray(&dummy_views_refs),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&dummy_sampler),
                },
            ],
            label: Some("Dummy Texture Bind Group"),
        });

        let dummy_env_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&dummy_view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&dummy_sampler),
                },
            ],
            label: Some("Dummy Env Bind Group"),
        });

        let mut texture_registry = LruCache::new(NonZeroUsize::new(255).unwrap());
        let mut texture_bind_groups = Vec::new();

        texture_registry.put("__mega_heim".to_string(), 0);
        texture_bind_groups.push(mega_heim_bind_group.clone());

        // Forge the Anvil (Buffers)
        let vertex_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Surtr Vertex Anvil"),
            size: (MAX_VERTICES * std::mem::size_of::<Vertex>()) as u64,
            usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        let index_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Surtr Index Anvil"),
            size: (MAX_INDICES * std::mem::size_of::<u32>()) as u64,
            usage: wgpu::BufferUsages::INDEX | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });
        let instance_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Surtr Instance Anvil"),
            size: (MAX_VERTICES / 4 * std::mem::size_of::<InstanceData>()) as u64,
            usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        // Forge the Heart (Berserker Uniforms)
        let current_theme = ColorTheme::default();
        use wgpu::util::DeviceExt;
        let theme_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Surtr Theme Buffer"),
            contents: bytemuck::bytes_of(&current_theme),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        let (width, height, scale_factor) = if let Some((ref window, _, ref config)) = surface_info
        {
            (config.width, config.height, window.scale_factor() as f32)
        } else if let Some((w, h, _)) = headless_info {
            (w, h, 1.0)
        } else {
            (1280, 720, 1.0)
        };

        let mut current_scene =
            SceneUniforms::new(width as f32 / scale_factor, height as f32 / scale_factor);
        current_scene.scale_factor = scale_factor;
        let scene_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Surtr Scene Buffer"),
            contents: bytemuck::bytes_of(&current_scene),
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
        });

        let berserker_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &berserker_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: theme_buffer.as_entire_binding(),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: scene_buffer.as_entire_binding(),
                },
            ],
            label: Some("Surtr Berserker Bind Group"),
        });

        let mut registry = crate::kvasir::registry::ResourceRegistry::new();
        let mut surfaces = std::collections::HashMap::new();
        let mut current_window = None;
        let mut headless_context = None;

        if let Some((window, surface, config)) = surface_info {
            let window_id = window.id();
            let ctx = Self::create_surface_context(
                &device,
                surface,
                config,
                &env_bind_group_layout,
                &texture_bind_group_layout,
                scale_factor,
                &mut registry,
            );
            surfaces.insert(window_id, ctx);
            current_window = Some(window_id);
        } else if let Some((w, h, f)) = headless_info {
            headless_context = Some(Self::create_headless_context(
                &device,
                w,
                h,
                f,
                &env_bind_group_layout,
                &texture_bind_group_layout,
                &mut registry,
            ));
        }

        let staging_belt = wgpu::util::StagingBelt::new((*device).clone(), 1024 * 1024);

        let glass_output_bind_group_layout = env_bind_group_layout.clone();

        // Color blindness pipeline layout (1 bind group: texture + sampler + uniform)
        let color_blind_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("Color Blind Bind Group Layout"),
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        view_dimension: wgpu::TextureViewDimension::D2,
                        multisampled: false,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(std::mem::size_of::<
                            crate::color_blindness::ColorBlindUniforms,
                        >() as u64),
                    },
                    count: None,
                },
            ],
        });
        let color_blind_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: Some("Color Blind Pipeline Layout"),
                bind_group_layouts: &[Some(&color_blind_bgl)],
                immediate_size: 0,
            });

        // Color blindness shader module and pipeline (separate from main shader)
        let color_blind_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Surtr Color Blind Shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(
                crate::color_blindness::shader_source(),
            )),
        });
        let color_blind_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Surtr Color Blindness"),
            layout: Some(&color_blind_pipeline_layout),
            vertex: wgpu::VertexState {
                module: &color_blind_shader,
                entry_point: Some("fs_main_vs"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &color_blind_shader,
                entry_point: Some("fs_color_blind"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // Volumetric raymarching pipeline (fullscreen triangle with SDF raymarch).
        // Uses the dedicated volumetric.wgsl shader for fog/light shaft effects.
        // Now includes scene uniforms for time-based animation and light positioning.
        let volumetric_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Surtr Volumetric Shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(include_str!(
                "shaders/volumetric.wgsl"
            ))),
        });
        // Volumetric bind group layout: uniform buffer for time/resolution/light
        let volumetric_bgl =
            device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: Some("Volumetric Bind Group Layout"),
                entries: &[wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(
                            std::mem::size_of::<[f32; 16]>() as u64
                        ),
                    },
                    count: None,
                }],
            });
        let volumetric_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Surtr Volumetric Layout"),
            bind_group_layouts: &[Some(&volumetric_bgl)],
            immediate_size: 0,
        });

        let volumetric_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Surtr Volumetric Raymarching"),
            layout: Some(&volumetric_layout),
            vertex: wgpu::VertexState {
                module: &volumetric_shader,
                entry_point: Some("vs_fullscreen"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &volumetric_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format: wgpu::TextureFormat::Rgba16Float,
                    blend: Some(wgpu::BlendState {
                        color: wgpu::BlendComponent {
                            src_factor: wgpu::BlendFactor::One,
                            dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
                            operation: wgpu::BlendOperation::Add,
                        },
                        alpha: wgpu::BlendComponent {
                            src_factor: wgpu::BlendFactor::One,
                            dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
                            operation: wgpu::BlendOperation::Add,
                        },
                    }),
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // HDR tone mapping pipeline (ACES filmic tone mapping).
        // Converts HDR scene to LDR for display. Falls back to passthrough on LDR surfaces.
        let tonemap_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
            label: Some("Surtr ToneMap Shader"),
            source: wgpu::ShaderSource::Wgsl(std::borrow::Cow::Borrowed(WGSL_TONEMAP)),
        });
        let tonemap_bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: Some("ToneMap Bind Group Layout"),
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: wgpu::BufferSize::new(
                            std::mem::size_of::<[f32; 4]>() as u64
                        ),
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Texture {
                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
                        view_dimension: wgpu::TextureViewDimension::D2,
                        multisampled: false,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStages::FRAGMENT,
                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                    count: None,
                },
            ],
        });
        let tonemap_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: Some("Surtr ToneMap Layout"),
            bind_group_layouts: &[Some(&tonemap_bgl)],
            immediate_size: 0,
        });
        let tonemap_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Surtr ToneMapping"),
            layout: Some(&tonemap_layout),
            vertex: wgpu::VertexState {
                module: &tonemap_shader,
                entry_point: Some("vs_fullscreen"),
                buffers: &[],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            },
            fragment: Some(wgpu::FragmentState {
                module: &tonemap_shader,
                entry_point: Some("fs_main"),
                targets: &[Some(wgpu::ColorTargetState {
                    format,
                    blend: None,
                    write_mask: wgpu::ColorWrites::ALL,
                })],
                compilation_options: wgpu::PipelineCompilationOptions::default(),
            }),
            primitive: wgpu::PrimitiveState::default(),
            depth_stencil: None,
            multisample: wgpu::MultisampleState::default(),
            multiview_mask: None,
            cache: None,
        });

        // Tone map uniform buffer (exposure, gamma)
        let color_blind_uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Color Blind Uniforms"),
            size: std::mem::size_of::<crate::color_blindness::ColorBlindUniforms>() as u64,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        // Volumetric uniform buffer (updated each frame for time/resolution/light)
        let volumetric_uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Volumetric Uniforms"),
            size: std::mem::size_of::<[f32; 16]>() as u64,
            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            mapped_at_creation: false,
        });

        // Sampler for the color blindness pass (and other post-process passes)
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        Self {
            registry,
            ai_material_rx: None,
            active_offscreens: Vec::new(),
            effect_pipelines: std::collections::HashMap::new(),
            effect_params_buffer: device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Dummy Effect Buffer"),
                size: 256,
                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            }),
            effect_params_bind_group: device.create_bind_group(&wgpu::BindGroupDescriptor {
                label: Some("Dummy Effect Bind Group"),
                layout: &device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                    label: None,
                    entries: &[],
                }),
                entries: &[],
            }),
            linear_sampler: device.create_sampler(&wgpu::SamplerDescriptor {
                label: Some("Linear Sampler"),
                address_mode_u: wgpu::AddressMode::ClampToEdge,
                address_mode_v: wgpu::AddressMode::ClampToEdge,
                address_mode_w: wgpu::AddressMode::ClampToEdge,
                mag_filter: wgpu::FilterMode::Linear,
                min_filter: wgpu::FilterMode::Linear,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                ..Default::default()
            }),
            instance,
            adapter,
            device: device.clone(),
            queue: queue.clone(),

            surfaces,
            current_window,
            headless_context,
            pipeline,
            opaque_pipeline,
            ui_pipeline,
            glass_pipeline,
            bloom_extract_pipeline,
            copy_pipeline,
            composite_pipeline,
            env_bind_group_layout,
            text_engine: cvkg_runic_text::RunicTextEngine::default(),
            mega_heim_tex,
            mega_heim_bind_group,
            text_cache: LruCache::new(NonZeroUsize::new(2048).unwrap()),
            shaped_text_cache: std::collections::HashMap::new(),
            heim_packer: SundrPacker::new(4096, 4096),
            image_uv_registry: {
                let mut cache = LruCache::new(NonZeroUsize::new(256).unwrap());
                cache.put("__mega_heim".to_string(), cvkg_core::Rect { x: 0.0, y: 0.0, width: 1.0, height: 1.0 });
                cache
            },
            texture_registry,
            texture_views: texture_views_list,
            dummy_sampler,
            svg_cache: LruCache::new(NonZeroUsize::new(128).unwrap()),
            svg_trees: LruCache::new(NonZeroUsize::new(128).unwrap()),
            filter_engine: Some(
                cvkg_svg_filters::FilterEngine::new(cvkg_svg_filters::GpuContext {
                    device: device.clone(),
                    queue: queue.clone(),
                })
                .expect("Failed to create SVG filter engine"),
            ),
            filter_batches: Vec::new(),
            dummy_texture_bind_group,
            dummy_env_bind_group,
            texture_bind_group_layout,
            texture_bind_groups,
            shared_elements: LruCache::new(NonZeroUsize::new(1024).unwrap()),
            vertex_buffer,
            index_buffer,
            instance_buffer,
            vertices: Vec::with_capacity(MAX_VERTICES),
            indices: Vec::with_capacity(MAX_INDICES),
            instance_data: Vec::with_capacity(MAX_VERTICES / 4),
            draw_calls: Vec::new(),
            current_texture_id: None,
            opacity_stack: vec![1.0],
            clip_stack: Vec::new(),
            slice_stack: Vec::new(),
            shadow_stack: Vec::new(),
            theme_buffer,
            scene_buffer,
            berserker_bind_group,
            berserker_bind_group_layout,
            start_time: std::time::Instant::now(),
            current_theme,
            current_scene,
            background_pipeline,
            current_z: 0.0,
            telemetry: cvkg_core::TelemetryData::default(),
            last_frame_start: std::time::Instant::now(),
            last_redraw_start: std::time::Instant::now(),
            frame_budget: cvkg_core::FrameBudget::default(),
            capture_staging_buffer: None,
            compositor_index_cursor: 0,
            vram_buffers_bytes: 0,
            vram_textures_bytes: 0,
            _debug_layout: false,
            transform_stack: Vec::new(),
            redraw_requested: false,
            skuld_queries,
            skuld_buffer,
            skuld_read_buffer,
            skuld_period,
            last_gpu_time_ns: 0,
            vnode_stack: Vec::new(),
            event_handlers: std::collections::HashMap::new(),
            staging_belt,
            staging_command_buffers: Vec::new(),
            glass_output_bind_group_layout,
            current_draw_material: cvkg_core::DrawMaterial::Opaque,
            portal_regions: VecDeque::new(),
            cached_graph_plan: None,
            memo_cache: std::collections::HashMap::new(),
            bloom_enabled: true,
            volumetric_enabled: false,
            color_blind_mode: crate::color_blindness::ColorBlindMode::Normal,
            color_blind_intensity: 1.0,
            color_blind_pipeline,
            volumetric_pipeline,
            volumetric_bind_group_layout: volumetric_bgl,
            volumetric_uniform_buffer,
            color_blind_bind_group_layout: color_blind_bgl,
            color_blind_uniform_buffer,
            sampler,
            kawase_down_pipeline,
            kawase_up_pipeline,
            kawase_bind_group_layout: kawase_bgl,
            kawase_uniform: device.create_buffer(&wgpu::BufferDescriptor {
                label: Some("Kawase Persistent Uniform"),
                size: 32,
                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
                mapped_at_creation: false,
            }),
            bind_group_cache: std::sync::Mutex::new(std::collections::HashMap::new()),
            texture_view_cache: std::sync::Mutex::new(std::collections::HashMap::new()),
        }
    }

    pub(crate) fn rebuild_texture_array_bind_group(&mut self) {
        let views: Vec<&wgpu::TextureView> = self.texture_views.iter().collect();
        self.mega_heim_bind_group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &self.texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureViewArray(&views),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&self.dummy_sampler),
                },
            ],
            label: Some("Surtr Texture Array Bind Group"),
        });
    }

    /// Update VRAM telemetry based on currently allocated resources.
    pub(crate) fn update_vram_telemetry(&mut self) {
        // Calculate Buffer VRAM
        let mut buffer_bytes = 0;
        buffer_bytes += (MAX_VERTICES * std::mem::size_of::<Vertex>()) as u64;
        buffer_bytes += (MAX_INDICES * std::mem::size_of::<u32>()) as u64;
        buffer_bytes += std::mem::size_of::<cvkg_core::ColorTheme>() as u64;
        buffer_bytes += std::mem::size_of::<cvkg_core::SceneUniforms>() as u64;
        self.vram_buffers_bytes = buffer_bytes;

        // Calculate Texture VRAM
        let mut texture_bytes = 0;
        texture_bytes += 4096 * 4096 * 4; // Mega Heim (RGBA8)
        texture_bytes += 4; // Dummy (RGBA8)

        for ctx in self.surfaces.values() {
            let bpp = 4;
            let surface_bytes = (ctx.config.width * ctx.config.height * bpp) as u64;
            texture_bytes += surface_bytes * 3; // scene (1x), depth (1x), blur a/b (0.5x), bloom a/b (0.5x)
        }

        self.vram_textures_bytes = texture_bytes;

        self.telemetry.vram_buffers_mb = buffer_bytes as f32 / 1_048_576.0;
        self.telemetry.vram_textures_mb = texture_bytes as f32 / 1_048_576.0;
        self.telemetry.vram_pipelines_mb = 0.0;
        self.telemetry.vram_usage_mb =
            self.telemetry.vram_buffers_mb + self.telemetry.vram_textures_mb;
    }

    /// Get real-time performance telemetry.
    pub fn get_telemetry(&self) -> cvkg_core::TelemetryData {
        self.telemetry.clone()
    }

    /// resize — Reconfigures a specific surface and its internal textures.
    pub fn resize(
        &mut self,
        window_id: winit::window::WindowId,
        width: u32,
        height: u32,
        scale_factor: f32,
    ) {
        if width > 0
            && height > 0
            && let Some(ctx) = self.surfaces.get_mut(&window_id)
        {
            if ctx.config.width == width && ctx.config.height == height {
                // Ignore redundant resizes to prevent Wayland protocol errors (ERROR_SURFACE_LOST_KHR / syncobj already exists)
                return;
            }

            log::info!("[GPU] Reconfiguring surface: {}x{}", width, height);
            self.bind_group_cache.lock().unwrap().clear();
            self.texture_view_cache.lock().unwrap().clear();
            self.shaped_text_cache.clear();
            ctx.config.width = width;
            ctx.config.height = height;
            ctx.scale_factor = scale_factor;
            ctx.surface.configure(&self.device, &ctx.config);

            // Re-create Muspelheim textures for this surface
            let texture_desc = wgpu::TextureDescriptor {
                label: Some("Surtr Scene Texture"),
                size: wgpu::Extent3d {
                    width,
                    height,
                    depth_or_array_layers: 1,
                },
                mip_level_count: 1,
                sample_count: 1,
                dimension: wgpu::TextureDimension::D2,
                format: wgpu::TextureFormat::Rgba16Float,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING,
                view_formats: &[],
            };

            let scene_tex = self.device.create_texture(&texture_desc);

            let msaa_desc = wgpu::TextureDescriptor {
                label: Some("Scene MSAA"),
                size: texture_desc.size,
                mip_level_count: 1,
                sample_count: 4,
                dimension: wgpu::TextureDimension::D2,
                format: wgpu::TextureFormat::Rgba16Float,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
                view_formats: &[],
            };
            let scene_msaa_tex = self.device.create_texture(&msaa_desc);
            ctx.scene_texture = scene_tex.create_view(&wgpu::TextureViewDescriptor::default());
            ctx.scene_msaa_texture =
                scene_msaa_tex.create_view(&wgpu::TextureViewDescriptor::default());

            self.registry.remove_image(ctx.blur_tex_a);
            self.registry.remove_image(ctx.blur_tex_b);
            self.registry.remove_image(ctx.bloom_tex_a);
            self.registry.remove_image(ctx.bloom_tex_b);

            let blur_width = (width / 2).max(1);
            let blur_height = (height / 2).max(1);

            let blur_desc_a = crate::kvasir::resource::ResourceDescriptor {
                label: Some("Surtr Blur Texture A".into()),
                kind: crate::kvasir::resource::ResourceKind::Image {
                    format: ctx.config.format,
                    width: blur_width,
                    height: blur_height,
                    mip_level_count: 6,
                    usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                        | wgpu::TextureUsages::TEXTURE_BINDING
                        | wgpu::TextureUsages::COPY_SRC,
                },
                lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
            };
            ctx.blur_tex_a = self.registry.allocate_image(&self.device, &blur_desc_a);

            let blur_desc_b = crate::kvasir::resource::ResourceDescriptor {
                label: Some("Surtr Blur Texture B".into()),
                kind: crate::kvasir::resource::ResourceKind::Image {
                    format: ctx.config.format,
                    width: blur_width,
                    height: blur_height,
                    mip_level_count: 6,
                    usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                        | wgpu::TextureUsages::TEXTURE_BINDING
                        | wgpu::TextureUsages::COPY_SRC,
                },
                lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
            };
            ctx.blur_tex_b = self.registry.allocate_image(&self.device, &blur_desc_b);

            let bloom_desc_a = crate::kvasir::resource::ResourceDescriptor {
                label: Some("Surtr Bloom Texture A".into()),
                kind: crate::kvasir::resource::ResourceKind::Image {
                    format: ctx.config.format,
                    width: blur_width,
                    height: blur_height,
                    mip_level_count: 6,
                    usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                        | wgpu::TextureUsages::TEXTURE_BINDING
                        | wgpu::TextureUsages::COPY_SRC,
                },
                lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
            };
            ctx.bloom_tex_a = self.registry.allocate_image(&self.device, &bloom_desc_a);

            let bloom_desc_b = crate::kvasir::resource::ResourceDescriptor {
                label: Some("Surtr Bloom Texture B".into()),
                kind: crate::kvasir::resource::ResourceKind::Image {
                    format: ctx.config.format,
                    width: blur_width,
                    height: blur_height,
                    mip_level_count: 6,
                    usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                        | wgpu::TextureUsages::TEXTURE_BINDING
                        | wgpu::TextureUsages::COPY_SRC,
                },
                lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
            };
            ctx.bloom_tex_b = self.registry.allocate_image(&self.device, &bloom_desc_b);

            // Re-create bind groups for this surface
            ctx.scene_bind_group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
                layout: &self.env_bind_group_layout,
                entries: &[
                    wgpu::BindGroupEntry {
                        binding: 0,
                        resource: wgpu::BindingResource::TextureView(&ctx.scene_texture),
                    },
                    wgpu::BindGroupEntry {
                        binding: 1,
                        resource: wgpu::BindingResource::Sampler(&ctx.sampler),
                    },
                ],
                label: Some("Scene Bind Group Resize"),
            });

            let scene_views: Vec<&wgpu::TextureView> =
                (0..256).map(|_| &ctx.scene_texture).collect();
            ctx.scene_texture_bind_group =
                self.device.create_bind_group(&wgpu::BindGroupDescriptor {
                    layout: &self.texture_bind_group_layout,
                    entries: &[
                        wgpu::BindGroupEntry {
                            binding: 0,
                            resource: wgpu::BindingResource::TextureViewArray(&scene_views),
                        },
                        wgpu::BindGroupEntry {
                            binding: 1,
                            resource: wgpu::BindingResource::Sampler(&ctx.sampler),
                        },
                    ],
                    label: Some("Scene Texture Bind Group Resize"),
                });

            let depth_texture = self.device.create_texture(&wgpu::TextureDescriptor {
                label: Some("Surtr Depth Texture"),
                size: wgpu::Extent3d {
                    width,
                    height,
                    depth_or_array_layers: 1,
                },
                mip_level_count: 1,
                sample_count: 4,
                dimension: wgpu::TextureDimension::D2,
                format: wgpu::TextureFormat::Depth32Float,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
                view_formats: &[],
            });
            ctx.depth_texture_view =
                depth_texture.create_view(&wgpu::TextureViewDescriptor::default());
        }
    }

    /// begin_frame_headless — Strike the flaming sword to begin a new GPU frame for headless rendering.
    pub fn begin_frame_headless(&mut self) -> wgpu::CommandEncoder {
        self.current_window = None;
        self.vertices.clear();
        self.indices.clear();
        self.instance_data.clear();
        self.draw_calls.clear();
        self.filter_batches.clear();
        self.shared_elements.clear();
        self.current_texture_id = None;
        self.opacity_stack = vec![1.0];
        self.clip_stack.clear();
        self.slice_stack.clear();
        self.transform_stack.clear();
        self.portal_regions.clear(); // Clear portal regions for fresh frame
        self.current_z = 0.0;
        self.compositor_index_cursor = self.indices.len() as u32;
        self.vnode_stack.clear();
        self.event_handlers.clear();

        // Clear memoization cache at the start of each frame
        self.memo_cache.clear();

        self.last_frame_start = std::time::Instant::now();
        self.telemetry.draw_calls = 0;
        self.telemetry.vertices = 0;

        // Recall staging belt buffers so they can be reused for vertex upload
        self.staging_belt.recall();

        let ctx = self
            .headless_context
            .as_ref()
            .expect("Headless context not initialized");
        let time = self.start_time.elapsed().as_secs_f32();
        let logical_w = ctx.width as f32 / ctx.scale_factor;
        let logical_h = ctx.height as f32 / ctx.scale_factor;
        let dt = time - self.current_scene.time;
        self.current_scene.time = time;
        self.current_scene.delta_time = dt;
        self.current_scene.resolution = [logical_w, logical_h];
        self.current_scene.scale_factor = ctx.scale_factor;
        self.current_scene.proj =
            glam::Mat4::orthographic_lh(0.0, logical_w, logical_h, 0.0, -1000.0, 1000.0);

        self.queue.write_buffer(
            &self.scene_buffer,
            0,
            bytemuck::bytes_of(&self.current_scene),
        );

        self.device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Surtr Headless Command Encoder"),
            })
    }

    /// begin_frame — Strike the flaming sword to begin a new GPU frame for a specific window.
    pub fn begin_frame(&mut self, window_id: winit::window::WindowId) -> wgpu::CommandEncoder {
        // Drain AI material channel
        if let Some(rx) = &self.ai_material_rx {
            while let Ok(res) = rx.try_recv() {
                match res {
                    Ok(_) => log::info!("[Surtr] Received AI generated material"),
                    Err(e) => log::warn!("[Surtr] AI material generation error: {:?}", e),
                }
            }
        }

        // Skuld: Read the timestamps from the previous frame
        if let Some(rb) = &self.skuld_read_buffer {
            let slice = rb.slice(..);
            let (tx, rx) = std::sync::mpsc::channel();
            slice.map_async(wgpu::MapMode::Read, move |r| {
                let _ = tx.send(r);
            });

            // Poll to ensure mapping is complete
            self.device
                .poll(wgpu::PollType::Wait {
                    submission_index: None,
                    timeout: None,
                })
                .unwrap();

            if rx.recv().is_ok() {
                let data = slice.get_mapped_range();
                let timestamps: [u64; 2] = bytemuck::cast_slice(&data).try_into().unwrap_or([0, 0]);
                drop(data);
                rb.unmap();

                if timestamps[1] > timestamps[0] {
                    let diff_ticks = timestamps[1] - timestamps[0];
                    self.last_gpu_time_ns = (diff_ticks as f64 * self.skuld_period as f64) as u64;
                    log::trace!(
                        "[Skuld] GPU time: {} ms",
                        self.last_gpu_time_ns as f64 / 1_000_000.0
                    );
                }
            }
        }

        self.staging_belt.recall();
        self.current_window = Some(window_id);
        self.vertices.clear();
        self.indices.clear();
        self.instance_data.clear();
        self.draw_calls.clear();
        self.filter_batches.clear();
        self.shared_elements.clear();
        self.current_texture_id = None;
        self.opacity_stack = vec![1.0];
        self.clip_stack.clear();
        self.slice_stack.clear();
        self.transform_stack.clear();
        self.portal_regions.clear(); // Clear portal regions for fresh frame
        self.current_z = 0.0;
        self.vnode_stack.clear();
        self.event_handlers.clear();

        // Clear memoization cache at the start of each frame
        self.memo_cache.clear();

        self.last_frame_start = std::time::Instant::now();
        self.telemetry.draw_calls = 0;
        self.telemetry.vertices = 0;

        let ctx = self
            .surfaces
            .get(&window_id)
            .expect("Window not registered");
        let time = self.start_time.elapsed().as_secs_f32();
        let logical_w = ctx.config.width as f32 / ctx.scale_factor;
        let logical_h = ctx.config.height as f32 / ctx.scale_factor;
        let dt = time - self.current_scene.time;
        self.current_scene.time = time;
        self.current_scene.delta_time = dt;
        self.current_scene.resolution = [logical_w, logical_h];
        self.current_scene.scale_factor = ctx.scale_factor;
        self.current_scene.proj =
            glam::Mat4::orthographic_lh(0.0, logical_w, logical_h, 0.0, -1000.0, 1000.0);

        self.queue.write_buffer(
            &self.scene_buffer,
            0,
            bytemuck::bytes_of(&self.current_scene),
        );

        self.device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Surtr Command Encoder"),
            })
    }

    /// register_window — Attaches a new OS window to the shared GPU context.
    pub fn register_window(&mut self, window: Arc<winit::window::Window>) {
        let size = window.inner_size();
        let surface = self
            .instance
            .create_surface(window.clone())
            .expect("Failed to create surface");
        let caps = surface.get_capabilities(&self.adapter);
        let format = caps.formats[0];

        // Dynamic present mode selection — Mailbox not available on all platforms (e.g. Wayland)
        let present_mode = if caps.present_modes.contains(&wgpu::PresentMode::Mailbox) {
            wgpu::PresentMode::Mailbox
        } else {
            log::warn!("[GPU] Mailbox not supported, falling back to Fifo (V-Sync)");
            wgpu::PresentMode::Fifo
        };

        let alpha_mode = if caps
            .alpha_modes
            .contains(&wgpu::CompositeAlphaMode::PostMultiplied)
        {
            wgpu::CompositeAlphaMode::PostMultiplied
        } else if caps
            .alpha_modes
            .contains(&wgpu::CompositeAlphaMode::PreMultiplied)
        {
            wgpu::CompositeAlphaMode::PreMultiplied
        } else {
            caps.alpha_modes[0]
        };

        log::info!(
            "[GPU] Configuring surface: {}x{} | {:?} | {:?}",
            size.width,
            size.height,
            present_mode,
            alpha_mode
        );

        let config = wgpu::SurfaceConfiguration {
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            format,
            width: size.width,
            height: size.height,
            present_mode,
            alpha_mode,
            view_formats: vec![],
            desired_maximum_frame_latency: 1,
        };
        surface.configure(&self.device, &config);

        let ctx = Self::create_surface_context(
            &self.device,
            surface,
            config,
            &self.env_bind_group_layout,
            &self.texture_bind_group_layout,
            window.scale_factor() as f32,
            &mut self.registry,
        );

        self.surfaces.insert(window.id(), ctx);
    }

    pub(crate) fn create_headless_context(
        device: &wgpu::Device,
        width: u32,
        height: u32,
        format: wgpu::TextureFormat,
        env_bind_group_layout: &wgpu::BindGroupLayout,
        texture_bind_group_layout: &wgpu::BindGroupLayout,
        registry: &mut crate::kvasir::registry::ResourceRegistry,
    ) -> HeadlessContext {
        let texture_desc = wgpu::TextureDescriptor {
            label: Some("Surtr Headless Scene Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba16Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                | wgpu::TextureUsages::TEXTURE_BINDING
                | wgpu::TextureUsages::COPY_SRC,
            view_formats: &[],
        };

        let scene_tex = device.create_texture(&texture_desc);

        let msaa_desc = wgpu::TextureDescriptor {
            label: Some("Scene MSAA"),
            size: texture_desc.size,
            mip_level_count: 1,
            sample_count: 4,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba16Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            view_formats: &[],
        };
        let scene_msaa_tex = device.create_texture(&msaa_desc);
        let scene_texture = scene_tex.create_view(&wgpu::TextureViewDescriptor::default());
        let scene_msaa_texture =
            scene_msaa_tex.create_view(&wgpu::TextureViewDescriptor::default());

        let blur_width = (width / 2).max(1);
        let blur_height = (height / 2).max(1);
        let blur_desc_a = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Headless Blur Texture A".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let blur_tex_a = registry.allocate_image(device, &blur_desc_a);

        let blur_desc_b = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Headless Blur Texture B".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let blur_tex_b = registry.allocate_image(device, &blur_desc_b);

        let bloom_desc_a = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Headless Bloom Texture A".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let bloom_tex_a = registry.allocate_image(device, &bloom_desc_a);

        let bloom_desc_b = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Headless Bloom Texture B".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let bloom_tex_b = registry.allocate_image(device, &bloom_desc_b);

        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        let scene_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&scene_texture),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Scene Bind Group"),
        });

        let blur_view_a = registry.get_texture_view(blur_tex_a).unwrap();
        let blur_view_b = registry.get_texture_view(blur_tex_b).unwrap();
        let bloom_view_a = registry.get_texture_view(bloom_tex_a).unwrap();
        let bloom_view_b = registry.get_texture_view(bloom_tex_b).unwrap();

        let blur_env_bind_group_a = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&blur_view_a),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Blur Env Bind Group A"),
        });
        let blur_env_bind_group_b = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&blur_view_b),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Blur Env Bind Group B"),
        });
        let bloom_env_bind_group_a = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&bloom_view_a),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Bloom Env Bind Group A"),
        });
        let bloom_env_bind_group_b = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&bloom_view_b),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Bloom Env Bind Group B"),
        });

        let scene_views: Vec<&wgpu::TextureView> = (0..256).map(|_| &scene_texture).collect();
        let scene_texture_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureViewArray(&scene_views),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Headless Scene Texture Bind Group"),
        });

        let depth_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Headless Depth Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 4,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Depth32Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            view_formats: &[],
        });
        let depth_texture_view = depth_texture.create_view(&wgpu::TextureViewDescriptor::default());

        let output_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Headless Output Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                | wgpu::TextureUsages::COPY_DST
                | wgpu::TextureUsages::COPY_SRC,
            view_formats: &[],
        });
        let output_view = output_texture.create_view(&wgpu::TextureViewDescriptor::default());

        crate::types::HeadlessContext {
            scene_texture,
            scene_msaa_texture,
            scene_bind_group,
            scene_texture_bind_group,
            depth_texture_view,
            blur_tex_a,
            blur_tex_b,
            bloom_tex_a,
            bloom_tex_b,
            blur_env_bind_group_a,
            blur_env_bind_group_b,
            bloom_env_bind_group_a,
            bloom_env_bind_group_b,
            scale_factor: 1.0,
            sampler,
            width,
            height,
            output_texture,
            output_view,
        }
    }

    pub(crate) fn create_surface_context(
        device: &wgpu::Device,
        surface: wgpu::Surface<'static>,
        config: wgpu::SurfaceConfiguration,
        env_bind_group_layout: &wgpu::BindGroupLayout,
        texture_bind_group_layout: &wgpu::BindGroupLayout,
        scale_factor: f32,
        registry: &mut crate::kvasir::registry::ResourceRegistry,
    ) -> SurfaceContext {
        let width = config.width;
        let height = config.height;

        let texture_desc = wgpu::TextureDescriptor {
            label: Some("Surtr Scene Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba16Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        };

        let scene_tex = device.create_texture(&texture_desc);

        let msaa_desc = wgpu::TextureDescriptor {
            label: Some("Scene MSAA"),
            size: texture_desc.size,
            mip_level_count: 1,
            sample_count: 4,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba16Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
            view_formats: &[],
        };
        let scene_msaa_tex = device.create_texture(&msaa_desc);
        let scene_texture = scene_tex.create_view(&wgpu::TextureViewDescriptor::default());
        let scene_msaa_texture =
            scene_msaa_tex.create_view(&wgpu::TextureViewDescriptor::default());

        let blur_width = (config.width / 2).max(1);
        let blur_height = (config.height / 2).max(1);
        let blur_desc_a = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Surface Blur Texture A".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format: config.format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let blur_tex_a = registry.allocate_image(device, &blur_desc_a);

        let blur_desc_b = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Surface Blur Texture B".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format: config.format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let blur_tex_b = registry.allocate_image(device, &blur_desc_b);

        let bloom_desc_a = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Surface Bloom Texture A".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format: config.format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let bloom_tex_a = registry.allocate_image(device, &bloom_desc_a);

        let bloom_desc_b = crate::kvasir::resource::ResourceDescriptor {
            label: Some("Surface Bloom Texture B".into()),
            kind: crate::kvasir::resource::ResourceKind::Image {
                format: config.format,
                width: blur_width,
                height: blur_height,
                mip_level_count: 6,
                usage: wgpu::TextureUsages::RENDER_ATTACHMENT
                    | wgpu::TextureUsages::TEXTURE_BINDING
                    | wgpu::TextureUsages::COPY_SRC,
            },
            lifetime: crate::kvasir::resource::ResourceLifetime::Persistent,
        };
        let bloom_tex_b = registry.allocate_image(device, &bloom_desc_b);

        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Linear,
            min_filter: wgpu::FilterMode::Linear,
            ..Default::default()
        });

        let scene_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&scene_texture),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Scene Bind Group"),
        });

        let blur_view_a = registry.get_texture_view(blur_tex_a).unwrap();
        let blur_view_b = registry.get_texture_view(blur_tex_b).unwrap();
        let bloom_view_a = registry.get_texture_view(bloom_tex_a).unwrap();
        let bloom_view_b = registry.get_texture_view(bloom_tex_b).unwrap();

        let blur_env_bind_group_a = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&blur_view_a),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Blur Env Bind Group A"),
        });
        let blur_env_bind_group_b = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&blur_view_b),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Blur Env Bind Group B"),
        });
        let bloom_env_bind_group_a = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&bloom_view_a),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Bloom Env Bind Group A"),
        });
        let bloom_env_bind_group_b = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: env_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&bloom_view_b),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Bloom Env Bind Group B"),
        });

        let scene_views: Vec<&wgpu::TextureView> = (0..256).map(|_| &scene_texture).collect();
        let scene_texture_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: texture_bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureViewArray(&scene_views),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: Some("Scene Texture Bind Group"),
        });

        let depth_texture = device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Surtr Depth Texture"),
            size: wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 4,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Depth32Float,
            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::TEXTURE_BINDING,
            view_formats: &[],
        });
        let depth_texture_view = depth_texture.create_view(&wgpu::TextureViewDescriptor::default());

        crate::types::SurfaceContext {
            surface,
            config,
            scene_texture,
            scene_msaa_texture,
            scene_bind_group,
            scene_texture_bind_group,
            depth_texture_view,
            blur_tex_a,
            blur_tex_b,
            bloom_tex_a,
            bloom_tex_b,
            blur_env_bind_group_a,
            blur_env_bind_group_b,
            bloom_env_bind_group_a,
            bloom_env_bind_group_b,
            scale_factor,
            sampler,
        }
    }

    pub fn reset_time(&mut self) {
        self.start_time = std::time::Instant::now();
    }

    /// reclaim_vram — Atomic recycling of the Mega-Heim and all associated caches.
    /// This prevents OOM and silent failures by quenching the heim when full.
    pub fn reclaim_vram(&mut self) {
        log::warn!("[GPU] Sundr Compaction: Compacting Mega-Heim...");

        let new_mega_heim_tex = self.device.create_texture(&wgpu::TextureDescriptor {
            label: Some("Sundr Mega-Heim (Compacted)"),
            size: wgpu::Extent3d {
                width: 4096,
                height: 4096,
                depth_or_array_layers: 1,
            },
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsages::TEXTURE_BINDING
                | wgpu::TextureUsages::COPY_DST
                | wgpu::TextureUsages::COPY_SRC,
            view_formats: &[],
        });

        let mut new_packer = SundrPacker::new(4096, 4096);
        let mut encoder = self
            .device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Heim Compaction Encoder"),
            });

        let image_entries: Vec<(String, Rect)> = self
            .image_uv_registry
            .iter()
            .map(|(k, v)| (k.clone(), *v))
            .collect();
        for (name, old_uv) in image_entries {
            if let Some(&tex_idx) = self.texture_registry.get(&name)
                && tex_idx == 0
            {
                let w_px = (old_uv.width * 4096.0).round() as u32;
                let h_px = (old_uv.height * 4096.0).round() as u32;
                let old_x_px = (old_uv.x * 4096.0).round() as u32;
                let old_y_px = (old_uv.y * 4096.0).round() as u32;

                if let Some((new_x, new_y)) = new_packer.pack(w_px, h_px) {
                    encoder.copy_texture_to_texture(
                        wgpu::TexelCopyTextureInfo {
                            texture: &self.mega_heim_tex,
                            mip_level: 0,
                            origin: wgpu::Origin3d {
                                x: old_x_px,
                                y: old_y_px,
                                z: 0,
                            },
                            aspect: wgpu::TextureAspect::All,
                        },
                        wgpu::TexelCopyTextureInfo {
                            texture: &new_mega_heim_tex,
                            mip_level: 0,
                            origin: wgpu::Origin3d {
                                x: new_x,
                                y: new_y,
                                z: 0,
                            },
                            aspect: wgpu::TextureAspect::All,
                        },
                        wgpu::Extent3d {
                            width: w_px,
                            height: h_px,
                            depth_or_array_layers: 1,
                        },
                    );

                    let new_uv = Rect {
                        x: new_x as f32 / 4096.0,
                        y: new_y as f32 / 4096.0,
                        width: old_uv.width,
                        height: old_uv.height,
                    };
                    self.image_uv_registry.put(name.clone(), new_uv);
                }
            }
        }

        let text_entries: Vec<(u64, (Rect, f32, f32, f32, f32))> =
            self.text_cache.iter().map(|(k, v)| (*k, *v)).collect();
        for (hash, (old_uv, w_f, h_f, x_off, y_off)) in text_entries {
            let w_px = (old_uv.width * 4096.0).round() as u32;
            let h_px = (old_uv.height * 4096.0).round() as u32;
            let old_x_px = (old_uv.x * 4096.0).round() as u32;
            let old_y_px = (old_uv.y * 4096.0).round() as u32;

            if let Some((new_x, new_y)) = new_packer.pack(w_px, h_px) {
                encoder.copy_texture_to_texture(
                    wgpu::TexelCopyTextureInfo {
                        texture: &self.mega_heim_tex,
                        mip_level: 0,
                        origin: wgpu::Origin3d {
                            x: old_x_px,
                            y: old_y_px,
                            z: 0,
                        },
                        aspect: wgpu::TextureAspect::All,
                    },
                    wgpu::TexelCopyTextureInfo {
                        texture: &new_mega_heim_tex,
                        mip_level: 0,
                        origin: wgpu::Origin3d {
                            x: new_x,
                            y: new_y,
                            z: 0,
                        },
                        aspect: wgpu::TextureAspect::All,
                    },
                    wgpu::Extent3d {
                        width: w_px,
                        height: h_px,
                        depth_or_array_layers: 1,
                    },
                );

                let new_uv = Rect {
                    x: new_x as f32 / 4096.0,
                    y: new_y as f32 / 4096.0,
                    width: old_uv.width,
                    height: old_uv.height,
                };
                self.text_cache.put(hash, (new_uv, w_f, h_f, x_off, y_off));
            }
        }

        self.queue.submit(std::iter::once(encoder.finish()));

        self.mega_heim_tex = new_mega_heim_tex;
        let mega_heim_view_obj = self
            .mega_heim_tex
            .create_view(&wgpu::TextureViewDescriptor::default());
        self.texture_views[0] = mega_heim_view_obj.clone();

        self.rebuild_texture_array_bind_group();

        if !self.texture_bind_groups.is_empty() {
            self.texture_bind_groups[0] = self.mega_heim_bind_group.clone();
        }

        self.heim_packer = new_packer;
        self.telemetry.vram_exhausted = false;
    }

    pub(crate) fn shatter_internal(
        &mut self,
        rect: Rect,
        pieces: u32,
        force: f32,
        color: [f32; 4],
        material_id: u32,
    ) {
        // High-Fidelity Variable Particle Density
        let count = (pieces as f32).sqrt().ceil() as u32;
        let dw = rect.width / count as f32;
        let dh = rect.height / count as f32;

        let c = self.apply_opacity(color);

        let cx = rect.x + rect.width * 0.5;
        let cy = rect.y + rect.height * 0.5;

        for y in 0..count {
            for x in 0..count {
                let init_x = rect.x + x as f32 * dw;
                let init_y = rect.y + y as f32 * dh;

                // Center of the shard relative to the card center
                let dx = (init_x + dw * 0.5) - cx;
                let dy = (init_y + dh * 0.5) - cy;
                let dist = (dx * dx + dy * dy).sqrt().max(1.0);

                // Normal direction outwards
                let nx = dx / dist;
                let ny = dy / dist;

                // Hash-based pseudo-random variations for dispersion
                let hash =
                    ((x as f32 * 12.9898 + y as f32 * 78.233).sin().fract() * 43_758.547).fract();
                let hash2 =
                    ((x as f32 * 37.11 + y as f32 * 149.87).sin().fract() * 23_412.19).fract();

                let speed_var = 0.5 + hash * 1.5;
                let angle = ny.atan2(nx) + (hash2 - 0.5) * 0.6;
                let disp_x = angle.cos() * force * 50.0 * speed_var;
                let disp_y = angle.sin() * force * 50.0 * speed_var;

                // Downward gravity-like drift over time/force
                let gravity = force * force * 20.0;

                // Shrink shard size as it scatters away
                // Assuming max force in demo is ~6.0
                let scale_factor = (1.0 - (force / 6.0).min(1.0)).max(0.0);
                let shard_w = dw * scale_factor;
                let shard_h = dh * scale_factor;

                let displaced_x = init_x + disp_x + (dw - shard_w) * 0.5;
                let displaced_y = init_y + disp_y + gravity + (dh - shard_h) * 0.5;

                let shard_rect = Rect {
                    x: displaced_x,
                    y: displaced_y,
                    width: shard_w,
                    height: shard_h,
                };

                let uv = Rect {
                    x: x as f32 / count as f32,
                    y: y as f32 / count as f32,
                    width: 1.0 / count as f32,
                    height: 1.0 / count as f32,
                };

                self.fill_rect_with_full_params(shard_rect, c, material_id, None, force, uv);
            }
        }
    }

    pub(crate) fn recursive_bolt(
        &mut self,
        from: [f32; 2],
        to: [f32; 2],
        depth: u32,
        color: [f32; 4],
    ) {
        if depth == 0 {
            self.draw_lightning_segment(from, to, color);
            return;
        }

        let mid_x = (from[0] + to[0]) * 0.5;
        let mid_y = (from[1] + to[1]) * 0.5;

        let dx = to[0] - from[0];
        let dy = to[1] - from[1];
        let len = (dx * dx + dy * dy).sqrt();

        if len < 1e-4 {
            return;
        }

        // Perpendicular offset for jaggedness
        let offset_scale = len * 0.15;
        let seed = (from[0] * 12.9898 + from[1] * 78.233 + (depth as f32) * 37.11)
            .sin()
            .fract();
        let offset_x = -dy / len * (seed - 0.5) * offset_scale;
        let offset_y = dx / len * (seed - 0.5) * offset_scale;

        let mid = [mid_x + offset_x, mid_y + offset_y];

        self.recursive_bolt(from, mid, depth - 1, color);
        self.recursive_bolt(mid, to, depth - 1, color);

        // 20% chance of a secondary branch
        if depth > 2 && seed > 0.8 {
            let branch_to = [
                mid[0] + offset_x * 2.0 + (seed * 100.0).sin() * 50.0,
                mid[1] + offset_y * 2.0 + (seed * 100.0).cos() * 50.0,
            ];
            self.recursive_bolt(mid, branch_to, depth - 2, color);
        }
    }

    pub(crate) fn draw_lightning_segment(&mut self, from: [f32; 2], to: [f32; 2], color: [f32; 4]) {
        let dx = to[0] - from[0];
        let dy = to[1] - from[1];
        let len = (dx * dx + dy * dy).sqrt();
        if len < 0.001 {
            return;
        }

        let glow_width = 32.0;
        let core_width = 4.0;
        let c = self.apply_opacity(color);

        // 1. Render Volumetric Glow (Cyan)
        let gnx = -dy / len * glow_width * 0.5;
        let gny = dx / len * glow_width * 0.5;
        let gp1 = [from[0] + gnx, from[1] + gny];
        let gp2 = [to[0] + gnx, to[1] + gny];
        let gp3 = [to[0] - gnx, to[1] - gny];
        let gp4 = [from[0] - gnx, from[1] - gny];
        self.push_oriented_quad(
            [gp1, gp2, gp3, gp4],
            c,
            9,
            Rect {
                x: 0.0,
                y: 0.0,
                width: 1.0,
                height: 1.0,
            },
        );

        // 2. Render Blinding Core (White)
        let cnx = -dy / len * core_width * 0.5;
        let cny = dx / len * core_width * 0.5;
        let cp1 = [from[0] + cnx, from[1] + cny];
        let cp2 = [to[0] + cnx, to[1] + cny];
        let cp3 = [to[0] - cnx, to[1] - cny];
        let cp4 = [from[0] - cnx, from[1] - cny];
        self.push_oriented_quad(
            [cp1, cp2, cp3, cp4],
            [1.0, 1.0, 1.0, c[3]],
            0,
            Rect {
                x: 0.0,
                y: 0.0,
                width: 1.0,
                height: 1.0,
            },
        );
    }

    pub(crate) fn push_oriented_quad(
        &mut self,
        points: [[f32; 2]; 4],
        color: [f32; 4],
        material_id: u32,
        uv_rect: Rect,
    ) {
        let scissor = self.clip_stack.last().copied();
        let texture_id = None; // Oriented quads like lightning don't use textures yet

        let (translation, scale_transform, rotation, _, _) = self.current_transform();
        let current_instance_data = InstanceData {
            translation,
            scale: scale_transform,
            rotation,
            blur_radius: 0.0,
            ior_override: 0.0,
        };

        if self.draw_calls.is_empty()
            || self.current_texture_id != texture_id
            || self.draw_calls.last().unwrap().scissor_rect != scissor
            || self.instance_data.last() != Some(&current_instance_data)
        {
            self.current_texture_id = texture_id;
            self.instance_data.push(current_instance_data);
            self.draw_calls.push(DrawCall {
                target_id: None,
                texture_id,
                scissor_rect: scissor,
                index_start: self.indices.len() as u32,
                index_count: 0,
                material: if material_id == 7 {
                    if let cvkg_core::DrawMaterial::Glass {
                        blur_radius,
                        ior_override,
                    } = self.current_draw_material
                    {
                        cvkg_core::DrawMaterial::Glass {
                            blur_radius,
                            ior_override,
                        }
                    } else {
                        cvkg_core::DrawMaterial::Glass {
                            blur_radius: 20.0,
                            ior_override: 0.0,
                        }
                    }
                } else if material_id == 6 {
                    cvkg_core::DrawMaterial::TopUI
                } else {
                    cvkg_core::DrawMaterial::Opaque
                },
                instance_start: (self.instance_data.len() - 1) as u32,
            });
        }

        let uvs = [
            [uv_rect.x, uv_rect.y],
            [uv_rect.x + uv_rect.width, uv_rect.y],
            [uv_rect.x + uv_rect.width, uv_rect.y + uv_rect.height],
            [uv_rect.x, uv_rect.y + uv_rect.height],
        ];

        let screen = [self.current_width() as f32, self.current_height() as f32];
        let rect = Rect {
            x: points[0][0],
            y: points[0][1],
            width: 1.0,
            height: 1.0,
        };

        for i in 0..4 {
            let px = points[i][0];
            let py = points[i][1];

            let (translation, scale_transform, rotation, _, _) = self.current_transform();
            self.vertices.push(Vertex {
                position: [px, py, 0.0],
                normal: [0.0, 0.0, 1.0],
                uv: uvs[i],
                color,
                material_id,
                radius: 0.0,
                slice: [0.0, 0.0, 0.0, 1.0],
                logical: [px - rect.x, py - rect.y],
                size: [rect.width, rect.height],
                clip: [-f32::INFINITY, -f32::INFINITY, f32::INFINITY, f32::INFINITY],
                tex_index: 0,
            });
        }

        if let Some(call) = self.draw_calls.last_mut() {
            call.index_count += 6;
        }
    }
    pub(crate) fn get_texture_id(&mut self, name: &str) -> Option<u32> {
        self.texture_registry.get(name).copied()
    }

    /// fill_rect_with_mode — Specialized rectangle drawing with mode-specific shader logic.
    pub fn fill_rect_with_mode(
        &mut self,
        rect: Rect,
        color: [f32; 4],
        material_id: u32,
        texture_id: Option<u32>,
    ) {
        self.fill_rect_with_full_params(
            rect,
            color,
            material_id,
            texture_id,
            0.0,
            Rect {
                x: 0.0,
                y: 0.0,
                width: 1.0,
                height: 1.0,
            },
        );
    }

    pub(crate) fn fill_rect_with_full_params(
        &mut self,
        rect: Rect,
        color: [f32; 4],
        material_id: u32,
        texture_id: Option<u32>,
        radius: f32,
        uv_rect: Rect,
    ) {
        // If a shadow is active, draw it first
        if let Some(shadow) = self.shadow_stack.last().copied()
            && shadow.color[3] > 0.001
        {
            Renderer::draw_drop_shadow(
                self,
                rect,
                radius,
                shadow.color,
                shadow.radius,
                0.0, // Spread
            );
        }

        let slice = self
            .slice_stack
            .last()
            .copied()
            .map(|(a, o)| [a, o, 1.0, 1.0])
            .unwrap_or([0.0, 0.0, 0.0, 1.0]);
        self.fill_rect_with_full_params_and_slice(
            rect,
            color,
            material_id,
            texture_id,
            radius,
            uv_rect,
            slice,
            [0.0, 0.0],
        );
    }

    #[allow(clippy::too_many_arguments)]
    pub(crate) fn fill_rect_with_full_params_and_slice(
        &mut self,
        rect: Rect,
        color: [f32; 4],
        material_id: u32,
        texture_id: Option<u32>,
        radius: f32,
        uv_rect: Rect,
        slice: [f32; 4],
        glyph_time: [f32; 2],
    ) {
        let scissor = self.clip_stack.last().copied();

        let material = if material_id == 7 {
            if let cvkg_core::DrawMaterial::Glass {
                blur_radius,
                ior_override,
            } = self.current_draw_material
            {
                cvkg_core::DrawMaterial::Glass {
                    blur_radius,
                    ior_override,
                }
            } else {
                cvkg_core::DrawMaterial::Glass {
                    blur_radius: 20.0,
                    ior_override: 0.0,
                }
            }
        } else if material_id == 6 {
            cvkg_core::DrawMaterial::TopUI
        } else {
            // Non-trivial algorithm: Draw Material Routing
            // WHY: Any material ID other than 7 (Glass) or 6 (TopUI/Text) is processed by the opaque WGSL pipeline.
            // Under immediate-mode rendering, inheriting self.current_draw_material can route shapes incorrectly.
            // CONTRACT: If the material ID is not Glass or TopUI, it maps directly to Opaque.
            cvkg_core::DrawMaterial::Opaque
        };

        let (translation, scale_transform, rotation, _, _) = self.current_transform();
        let (blur_radius, ior_override) = if let cvkg_core::DrawMaterial::Glass {
            blur_radius,
            ior_override,
        } = material
        {
            (blur_radius, ior_override)
        } else {
            (0.0, 0.0)
        };

        let current_instance_data = InstanceData {
            translation,
            scale: scale_transform,
            rotation,
            blur_radius,
            ior_override,
        };

        // Batching: check if we need to start a new DrawCall
        // With Texture Array, we no longer need to break batches when the texture changes,
        // as long as they are all part of the same array bind group (Group 0).
        let last_call = self.draw_calls.last();
        let needs_new_call = self.draw_calls.is_empty()
            || last_call.unwrap().scissor_rect != scissor
            || last_call.unwrap().material != material
            || self.instance_data.last() != Some(&current_instance_data);

        if needs_new_call {
            self.current_texture_id = Some(0); // All textures are now in the binding array at Group 0
            self.instance_data.push(current_instance_data);
            self.draw_calls.push(DrawCall {
                target_id: None,
                texture_id: self.current_texture_id,
                scissor_rect: scissor,
                index_start: self.indices.len() as u32,
                index_count: 0,
                material,
                instance_start: (self.instance_data.len() - 1) as u32,
            });
        }

        let scale = self.current_scale_factor();
        let snap = |v: f32| (v * scale).round() / scale;

        let base_idx = self.vertices.len() as u32;
        let x1 = snap(rect.x);
        let y1 = snap(rect.y);
        let x2 = snap(rect.x + rect.width);
        let y2 = snap(rect.y + rect.height);
        let z = self.current_z;
        let normal = [0.0, 0.0, 1.0];
        let screen = [self.current_width() as f32, self.current_height() as f32];
        let clip_rect = self.clip_stack.last().copied().unwrap_or(cvkg_core::Rect {
            x: -10000.0,
            y: -10000.0,
            width: 20000.0,
            height: 20000.0,
        });
        let clip = [clip_rect.x, clip_rect.y, clip_rect.width, clip_rect.height];

        let tex_index = texture_id.unwrap_or(0);

        self.vertices.push(Vertex {
            position: [x1, y1, z],
            normal,
            uv: [uv_rect.x, uv_rect.y],
            color,
            material_id,
            radius,
            slice,
            logical: [0.0, 0.0],
            size: [rect.width, rect.height],
            clip,
            tex_index,
        });
        self.vertices.push(Vertex {
            position: [x2, y1, z],
            normal,
            uv: [uv_rect.x + uv_rect.width, uv_rect.y],
            color,
            material_id,
            radius,
            slice,
            logical: [rect.width, 0.0],
            size: [rect.width, rect.height],
            clip,
            tex_index,
        });
        self.vertices.push(Vertex {
            position: [x2, y2, z],
            normal,
            uv: [uv_rect.x + uv_rect.width, uv_rect.y + uv_rect.height],
            color,
            material_id,
            radius,
            slice,
            logical: [rect.width, rect.height],
            size: [rect.width, rect.height],
            clip,
            tex_index,
        });
        self.vertices.push(Vertex {
            position: [x1, y2, z],
            normal,
            uv: [uv_rect.x, uv_rect.y + uv_rect.height],
            color,
            material_id,
            radius,
            slice,
            logical: [0.0, rect.height],
            size: [rect.width, rect.height],
            clip,
            tex_index,
        });

        self.indices.extend_from_slice(&[
            base_idx,
            base_idx + 1,
            base_idx + 2,
            base_idx,
            base_idx + 2,
            base_idx + 3,
        ]);

        if let Some(call) = self.draw_calls.last_mut() {
            call.index_count += 6;
        }
    }

    // ═══════════════════════════════════════════════════════════════════════════
    // Kvasir pass encoding methods
    // ═══════════════════════════════════════════════════════════════════════════
    // Each method encodes one render pass into the provided command encoder.
    // Called from end_frame() which assembles the graph-driven pass sequence.

    /// Pass 1: Clear scene+depth, draw atmosphere, draw opaque geometry.
    /// end_frame -- Quench the blade by submitting the full Muspelheim multi-pass effect.
    ///
    /// Since the Renderer 3.0 migration, the pass sequence is driven by a Kvasir
    /// dependency graph rather than hardcoded ordering. The graph is built each
    /// frame (cheap — just node/edge allocation), validated (cycle detection,
    /// input satisfiability), then executed. Conditional passes (glass, bloom,
    /// accessibility) are automatically eliminated when not needed.
    pub fn end_frame(&mut self, mut encoder: wgpu::CommandEncoder) {
        struct ActiveFrameResources {
            surface_texture: Option<wgpu::SurfaceTexture>,
            target_view: wgpu::TextureView,
            scene_texture: wgpu::TextureView,
            scene_msaa_texture: wgpu::TextureView,
            depth_texture_view: wgpu::TextureView,
            blur_env_bind_group_a: wgpu::BindGroup,
            blur_env_bind_group_b: wgpu::BindGroup,
            bloom_env_bind_group_a: wgpu::BindGroup,
            bloom_env_bind_group_b: wgpu::BindGroup,
        }

        let res = if let Some(window_id) = self.current_window {
            let Some(ctx) = self.surfaces.get(&window_id) else {
                log::error!("[GPU] Missing surface context for end_frame");
                return;
            };
            let frame = match ctx.surface.get_current_texture() {
                wgpu::CurrentSurfaceTexture::Success(t) => t,
                wgpu::CurrentSurfaceTexture::Suboptimal(t) => {
                    ctx.surface.configure(&self.device, &ctx.config);
                    t
                }
                other => {
                    log::warn!(
                        "[GPU] Surface texture acquisition failed ({:?}), reconfiguring surface",
                        other
                    );
                    ctx.surface.configure(&self.device, &ctx.config);
                    self.queue.submit(std::iter::once(encoder.finish()));
                    return;
                }
            };
            let view = frame
                .texture
                .create_view(&wgpu::TextureViewDescriptor::default());

            ActiveFrameResources {
                surface_texture: Some(frame),
                target_view: view,
                scene_texture: ctx.scene_texture.clone(),
                scene_msaa_texture: ctx.scene_msaa_texture.clone(),
                depth_texture_view: ctx.depth_texture_view.clone(),
                blur_env_bind_group_a: ctx.blur_env_bind_group_a.clone(),
                blur_env_bind_group_b: ctx.blur_env_bind_group_b.clone(),
                bloom_env_bind_group_a: ctx.bloom_env_bind_group_a.clone(),
                bloom_env_bind_group_b: ctx.bloom_env_bind_group_b.clone(),
            }
        } else {
            let Some(ctx) = self.headless_context.as_ref() else {
                log::error!("[GPU] No headless context for end_frame");
                return;
            };

            ActiveFrameResources {
                surface_texture: None,
                target_view: ctx.output_view.clone(),
                scene_texture: ctx.scene_texture.clone(),
                scene_msaa_texture: ctx.scene_msaa_texture.clone(),
                depth_texture_view: ctx.depth_texture_view.clone(),
                blur_env_bind_group_a: ctx.blur_env_bind_group_a.clone(),
                blur_env_bind_group_b: ctx.blur_env_bind_group_b.clone(),
                bloom_env_bind_group_a: ctx.bloom_env_bind_group_a.clone(),
                bloom_env_bind_group_b: ctx.bloom_env_bind_group_b.clone(),
            }
        };

        // ── Build and execute the Kvasir frame graph ─────────────────────────────
        let has_glass = self
            .draw_calls
            .iter()
            .any(|c| matches!(c.material, cvkg_core::DrawMaterial::Glass { .. }));
        let has_bloom = self.bloom_enabled;
        let has_accessibility =
            self.color_blind_mode != crate::color_blindness::ColorBlindMode::Normal;

        // Build the frame graph using the Kvasir helper for correct pass ordering.
        // Conditional passes (glass, bloom, accessibility) are included/excluded based on frame state.
        // This replaces the hardcoded if/else pass dispatch with a data-driven approach:
        // the graph declares which passes exist and their ordering, and we execute only enabled ones.
        //
        // NOTE: Geometry is uploaded by render_frame() via StagingBelt into staging_command_buffers.
        // Those staging commands must be submitted before the render pass encoders below, which is
        // guaranteed by inserting the render encoders after the existing staging entries (see submit block).

        let (blur_id, bloom_id) = if let Some(window_id) = self.current_window {
            let ctx = self.surfaces.get(&window_id).unwrap();
            (ctx.blur_tex_a, ctx.bloom_tex_a)
        } else {
            let ctx = self.headless_context.as_ref().unwrap();
            (ctx.blur_tex_a, ctx.bloom_tex_a)
        };
        self.registry.alias(kvasir::nodes::RES_BLUR_A, blur_id);
        self.registry.alias(kvasir::nodes::RES_BLOOM_A, bloom_id);
        self.registry
            .alias_view(kvasir::nodes::RES_SCENE, res.scene_texture.clone());
        self.registry.alias_view(
            kvasir::nodes::RES_SCENE_MSAA,
            res.scene_msaa_texture.clone(),
        );

        let scale = self.current_scale_factor();
        let scale_bits = scale.to_bits();
        let active_offscreens_count = self.active_offscreens.len();
        let portal_regions_count = self.portal_regions.len();
        let width = self.current_width();
        let height = self.current_height();
        let has_volumetric = self.volumetric_enabled;

        let use_cache = if let Some(ref cached) = self.cached_graph_plan {
            cached.matches(
                has_glass,
                has_bloom,
                has_accessibility,
                has_volumetric,
                active_offscreens_count,
                portal_regions_count,
                width,
                height,
                scale_bits,
            )
        } else {
            false
        };

        if !use_cache {
            let render_graph = kvasir::nodes::build_render_graph(&kvasir::nodes::RenderGraphConfig {
                has_glass,
                has_bloom,
                has_accessibility,
                has_volumetric,
                active_offscreens: &self.active_offscreens,
                portal_regions: &self.portal_regions.iter().cloned().collect::<Vec<_>>(),
                width,
                height,
                scale,
            });
            let planner = kvasir::planner::ExecutionPlanner::new(&render_graph);
            let compiled_plan = planner.compile().expect("RenderGraph cycle detected!");
            
            self.cached_graph_plan = Some(kvasir::graph_cache::CachedGraphPlan {
                has_glass,
                has_bloom,
                has_accessibility,
                has_volumetric,
                active_offscreens_count,
                portal_regions_count,
                width,
                height,
                scale_bits,
                graph: render_graph,
                plan: compiled_plan,
            });
        }

        let cached = self.cached_graph_plan.as_ref().unwrap();
        for &pass_id in &cached.plan {
            if let Some(node) = cached.graph.node(pass_id) {
                log::trace!("[Kvasir] Executing node: {}", node.label());
                let mut ctx = kvasir::node::ExecutionContext {
                    device: &self.device,
                    queue: &self.queue,
                    encoder: &mut encoder,
                    registry: &self.registry,
                    renderer: self,
                    target_view: &res.target_view,
                    depth_view: &res.depth_texture_view,
                    blur_env_bind_group_a: &res.blur_env_bind_group_a,
                    blur_env_bind_group_b: &res.blur_env_bind_group_b,
                    bloom_env_bind_group_a: &res.bloom_env_bind_group_a,
                    bloom_env_bind_group_b: &res.bloom_env_bind_group_b,
                    scale_factor: scale,
                };
                node.execute(&mut ctx);
            }
        }

        // ── Submit ─────────────────────────────────────────────────────────────
        // staging_command_buffers already contains the geometry upload encoder from
        // render_frame() (StagingBelt). The render pass encoders must come AFTER it
        // so the GPU sees vertex/index data before the draw calls that reference it.
        self.staging_command_buffers.push(encoder.finish());

        // Skuld: Resolve timestamps (preserved from original)
        if let (Some(q), Some(b), Some(rb)) = (
            &self.skuld_queries,
            &self.skuld_buffer,
            &self.skuld_read_buffer,
        ) {
            let mut resolve_encoder =
                self.device
                    .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                        label: Some("Skuld Resolve Encoder"),
                    });
            resolve_encoder.resolve_query_set(q, 0..2, b, 0);
            resolve_encoder.copy_buffer_to_buffer(b, 0, rb, 0, 16);
            self.staging_command_buffers.push(resolve_encoder.finish());
        }

        let cmds = std::mem::take(&mut self.staging_command_buffers);
        self.queue.submit(cmds);
        self.telemetry.frame_time_ms = self.last_frame_start.elapsed().as_secs_f32() * 1000.0;
        self.update_vram_telemetry();

        if let Some(f) = res.surface_texture {
            f.present();
        }
    }
}

impl Drop for SurtrRenderer {
    fn drop(&mut self) {
        // Ensure GPU is idle before dropping to avoid Swapchain semaphore panics
        let _ = self.device.poll(wgpu::PollType::Wait {
            submission_index: None,
            timeout: None,
        });
    }
}

impl SurtrRenderer {
    /// Submit pre-routed draw command buckets from the cvkg-compositor.
    ///
    /// Accepts `CommandBuckets` produced by `CompositorEngine::flatten_and_route()`
    /// and submits draw calls in the correct pass order for the Backdrop Capture
    /// Architecture:
    /// 1. Scene commands (opaque) → Scene Capture pass
    /// 2. Glass commands → Material Composite pass (samples blur pyramid)
    /// 3. Overlay commands → Top-Level Foreground pass
    pub fn submit_buckets(&mut self, buckets: &cvkg_compositor::CommandBuckets) {
        // Scene pass — opaque draw calls
        let mut active_offscreens = Vec::new();
        let mut current_target_id = None;

        for cmd in &buckets.scene_commands {
            match cmd {
                cvkg_compositor::engine::RenderCommand::Draw(routed) => {
                    self.set_material(cvkg_core::DrawMaterial::Opaque);
                    self.submit_routed(routed, current_target_id);
                }
                cvkg_compositor::engine::RenderCommand::PushOffscreen {
                    source_layer,
                    material,
                    bounds,
                } => {
                    current_target_id = Some(source_layer.0);

                    // Pre-allocate the texture
                    let width = (bounds.width).max(1.0) as u32;
                    let height = (bounds.height).max(1.0) as u32;
                    self.registry
                        .allocate_offscreen(&self.device, source_layer.0, [width, height]);

                    if let cvkg_compositor::Material::ShaderEffect {
                        effect_name,
                        params_json: _,
                        ..
                    } = material
                    {
                        active_offscreens.push(crate::types::OffscreenEffectConfig {
                            target_id: source_layer.0,
                            effect: effect_name.clone(),
                            blend_mode: 0,          // Default blend
                            effect_args: [0.0; 16], // Need to parse params_json
                        });
                    }
                }
                cvkg_compositor::engine::RenderCommand::PopOffscreen => {
                    current_target_id = None;
                }
            }
        }
        self.active_offscreens = active_offscreens;

        // Glass pass — glassmorphism draw calls sampling blur pyramid
        for cmd in &buckets.glass_commands {
            if let cvkg_compositor::engine::RenderCommand::Draw(routed) = cmd {
                let core_material = match routed.material {
                    cvkg_compositor::Material::Opaque => cvkg_core::DrawMaterial::Opaque,
                    cvkg_compositor::Material::Glass {
                        blur_radius,
                        depth_index: _,
                    } => cvkg_core::DrawMaterial::Glass {
                        blur_radius,
                        ior_override: 0.0,
                    },
                    cvkg_compositor::Material::Overlay => cvkg_core::DrawMaterial::TopUI,
                    _ => cvkg_core::DrawMaterial::Opaque,
                };
                self.set_material(core_material);
                self.submit_routed(routed, None);
            }
        }

        // Overlay pass — foreground UI (crisp text, icons, edge lighting)
        for cmd in &buckets.overlay_commands {
            if let cvkg_compositor::engine::RenderCommand::Draw(routed) = cmd {
                self.set_material(cvkg_core::DrawMaterial::TopUI);
                self.submit_routed(routed, None);
            }
        }
    }

    /// Submit a single routed draw command through the internal pipeline.
    pub(crate) fn submit_routed(
        &mut self,
        routed: &cvkg_compositor::RoutedDrawCommand,
        target_id: Option<u64>,
    ) {
        let cmd = &routed.command;
        if cmd.index_count == 0 {
            return;
        }
        let material = match &routed.material {
            cvkg_compositor::Material::Glass { blur_radius, .. } => {
                cvkg_core::DrawMaterial::Glass {
                    blur_radius: *blur_radius,
                    ior_override: 0.0,
                }
            }
            cvkg_compositor::Material::Overlay => cvkg_core::DrawMaterial::TopUI,
            _ => cvkg_core::DrawMaterial::Opaque,
        };
        self.draw_calls.push(DrawCall {
            texture_id: cmd.texture_id,
            scissor_rect: cmd.scissor_rect,
            index_start: cmd.index_start,
            index_count: cmd.index_count,
            material,
            target_id,
            instance_start: cmd.instance_id,
        });
    }
}

impl SurtrRenderer {
    /// Returns the current effective opacity (product of all stacked values).
    pub(crate) fn apply_opacity(&self, mut color: [f32; 4]) -> [f32; 4] {
        if let Some(&alpha) = self.opacity_stack.last() {
            color[3] *= alpha;
        }
        color
    }

    /// load_svg — Parses an SVG file and tessellates its paths into GPU triangles.
    pub fn load_svg(&mut self, name: &str, data: &[u8]) {
        if self.svg_cache.contains(name) {
            return;
        }

        let mut opt = usvg::Options::default();
        opt.fontdb_mut().load_system_fonts();
        let tree = match usvg::Tree::from_data(data, &opt) {
            Ok(t) => t,
            Err(e) => {
                log::error!("Failed to parse SVG '{}': {:?}, skipping load", name, e);
                return;
            }
        };

        let view_box = Rect {
            x: 0.0,
            y: 0.0,
            width: tree.size().width(),
            height: tree.size().height(),
        };

        let parsed_animations = parse_svg_animations(data);

        let mut vertices = Vec::new();
        let mut indices = Vec::new();
        let mut fill_tessellator = FillTessellator::new();
        let mut stroke_tessellator = StrokeTessellator::new();
        let mut finalized_animations = Vec::new();
        let mut paths = Vec::new();

        for child in tree.root().children() {
            let mut tess_params = TessellateParams {
                fill_tessellator: &mut fill_tessellator,
                stroke_tessellator: &mut stroke_tessellator,
                vertices: &mut vertices,
                indices: &mut indices,
                parsed_animations: &parsed_animations,
                finalized_animations: &mut finalized_animations,
                paths: &mut paths,
            };
            self.tessellate_node(child, &mut tess_params);
        }

        self.svg_cache.put(
            name.to_string(),
            SvgModel {
                vertices,
                indices,
                view_box,
                paths,
                animations: finalized_animations,
            },
        );
        self.svg_trees.put(name.to_string(), tree);
    }

    pub(crate) fn tessellate_node(&self, node: &usvg::Node, params: &mut TessellateParams<'_>) {
        let start_idx = params.vertices.len();
        let node_id = match node {
            usvg::Node::Group(g) => g.id().to_string(),
            usvg::Node::Path(p) => p.id().to_string(),
            _ => String::new(),
        };

        if let usvg::Node::Group(ref group) = *node {
            for child in group.children() {
                let mut child_params = TessellateParams {
                    fill_tessellator: params.fill_tessellator,
                    stroke_tessellator: params.stroke_tessellator,
                    vertices: params.vertices,
                    indices: params.indices,
                    parsed_animations: params.parsed_animations,
                    finalized_animations: params.finalized_animations,
                    paths: params.paths,
                };
                self.tessellate_node(child, &mut child_params);
            }
        } else if let usvg::Node::Path(ref path) = *node {
            let has_fill = path.fill().is_some();
            let has_stroke = path.stroke().is_some();

            // If neither fill nor stroke, log and skip
            if !has_fill && !has_stroke {
                log::debug!("SVG path '{}' has no fill or stroke, skipping", node_id);
                return;
            }

            let lyon_path = usvg_to_lyon(path, node.abs_transform());
            let screen = [4096.0, 4096.0]; // Placeholder, will be overridden if needed
            let clip = [-f32::INFINITY, -f32::INFINITY, f32::INFINITY, f32::INFINITY]; // Default clip

            // Tessellate fill if present
            if has_fill && let Some(fill) = path.fill() {
                let color = match fill.paint() {
                    usvg::Paint::Color(c) => [
                        c.red as f32 / 255.0,
                        c.green as f32 / 255.0,
                        c.blue as f32 / 255.0,
                        fill.opacity().get(),
                    ],
                    usvg::Paint::LinearGradient(_)
                    | usvg::Paint::RadialGradient(_)
                    | usvg::Paint::Pattern(_) => {
                        log::warn!(
                            "SVG path '{}' uses gradient/pattern fill which is not supported, using white fallback",
                            node_id
                        );
                        [1.0, 1.0, 1.0, 1.0]
                    }
                };

                let mut buffers: VertexBuffers<Vertex, u32> = VertexBuffers::new();
                let base_vertex_idx = params.vertices.len() as u32;

                if let Err(e) = params.fill_tessellator.tessellate_path(
                    &lyon_path,
                    &FillOptions::default(),
                    &mut BuffersBuilder::new(&mut buffers, SceneVertexConstructor { color }),
                ) {
                    log::warn!(
                        "SVG fill tessellation failed for path '{}': {:?}, skipping",
                        node_id,
                        e
                    );
                    return;
                }

                params.vertices.extend(buffers.vertices);
                for idx in buffers.indices {
                    params.indices.push(base_vertex_idx + idx);
                }
            }

            // Tessellate stroke if present
            if has_stroke && let Some(stroke) = path.stroke() {
                let base_vertex_idx = params.vertices.len() as u32;
                let stroke_width = stroke.width().get(); // Direct float value
                let color = match stroke.paint() {
                    usvg::Paint::Color(c) => [
                        c.red as f32 / 255.0,
                        c.green as f32 / 255.0,
                        c.blue as f32 / 255.0,
                        stroke.opacity().get(),
                    ],
                    usvg::Paint::LinearGradient(_)
                    | usvg::Paint::RadialGradient(_)
                    | usvg::Paint::Pattern(_) => {
                        log::warn!(
                            "SVG path '{}' uses gradient/pattern stroke which is not supported, using white fallback",
                            node_id
                        );
                        [1.0, 1.0, 1.0, 1.0]
                    }
                };

                let mut buffers: VertexBuffers<Vertex, u32> = VertexBuffers::new();

                let path_length = lyon::algorithms::length::approximate_length(&lyon_path, 0.1);

                if let Err(e) = params.stroke_tessellator.tessellate_path(
                    &lyon_path,
                    &StrokeOptions::default().with_line_width(stroke_width),
                    &mut BuffersBuilder::new(
                        &mut buffers,
                        CustomStrokeVertexConstructor { color, clip, path_length },
                    ),
                ) {
                    log::warn!(
                        "SVG stroke tessellation failed for path '{}': {:?}, skipping",
                        node_id,
                        e
                    );
                    return;
                }

                params.vertices.extend(buffers.vertices);
                for idx in buffers.indices {
                    params.indices.push(base_vertex_idx + idx);
                }
            }
        }

        let end_idx = params.vertices.len();
        let end_idx_indices = params.indices.len();
        if !node_id.is_empty() && start_idx < end_idx {
            for anim in params.parsed_animations {
                if anim.target_id == node_id {
                    let mut final_anim = anim.clone();
                    final_anim.vertex_range = start_idx..end_idx;
                    params.finalized_animations.push(final_anim);
                }
            }
            // Record this path's range for per-path transforms.
            params.paths.push(crate::types::SvgPath {
                    id: node_id,
                    vertex_range: start_idx..end_idx,
                    index_range: end_idx_indices..params.indices.len(),
                    local_transform: Default::default(),
                });
        }
    }

    /// draw_svg — Renders a pre-loaded SVG icon at the specified logical rect.
    /// animation_time_offset shifts the animation phase for this instance,
    /// allowing multiple draws of the same SVG to animate independently.
    pub fn draw_svg(&mut self, name: &str, rect: Rect, color: Option<[f32; 4]>, material_id: u32) {
        self.draw_svg_with_offset(name, rect, color, material_id, 0.0);
    }

    pub fn draw_svg_with_offset(&mut self, name: &str, rect: Rect, color: Option<[f32; 4]>, material_id: u32, animation_time_offset: f32) {
        let clip_rect = self.clip_stack.last().copied().unwrap_or(cvkg_core::Rect {
            x: -10000.0,
            y: -10000.0,
            width: 20000.0,
            height: 20000.0,
        });
        let scale = self.current_scale_factor();
        let screen_w = self.current_width() as f32 / scale;
        let screen_h = self.current_height() as f32 / scale;

        if rect.x > clip_rect.x + clip_rect.width
            || rect.x + rect.width < clip_rect.x
            || rect.y > clip_rect.y + clip_rect.height
            || rect.y + rect.height < clip_rect.y
        {
            return;
        }

        log::info!("DRAW_SVG '{}' called with rect: {:?}, model_view_box: {:?}", name, rect, self.svg_cache.get(name).map(|m| m.view_box));
        
        if rect.x > screen_w
            || rect.x + rect.width < 0.0
            || rect.y > screen_h
            || rect.y + rect.height < 0.0
        {
            return;
        }

        let model = if let Some(m) = self.svg_cache.get(name) {
            m.clone()
        } else {
            return;
        };

        let _scale_x = rect.width / model.view_box.width;
        let _scale_y = rect.height / model.view_box.height;
        let base_idx = self.vertices.len() as u32;
        let screen = [self.current_width() as f32, self.current_height() as f32];
        let clip_rect = self.clip_stack.last().copied().unwrap_or(cvkg_core::Rect {
            x: -10000.0,
            y: -10000.0,
            width: 20000.0,
            height: 20000.0,
        });
        let clip = [clip_rect.x, clip_rect.y, clip_rect.width, clip_rect.height];
        let scale = self.current_scale_factor();
        let snap = |v: f32| (v * scale).round() / scale;

        if model.paths.is_empty() {
            // Fallback: no path data, treat all vertices as one blob.
            let mut local_vertices = model.vertices.clone();
            Self::position_vertices(&mut local_vertices, model.view_box, rect, material_id, clip, snap);
            let base_vertex = self.vertices.len() as u32;
            self.vertices.extend(local_vertices);
            let index_count = model.indices.len();
            for idx in &model.indices {
                self.indices.push(base_vertex + *idx);
            }
            let material = Self::resolve_material(material_id);
            let tid = self.get_texture_id("__mega_heim");
            Self::emit_draw_call(self, material, tid, clip_rect, index_count as u32, base_vertex);
            // Emit single draw call for all vertices
            let material = Self::resolve_material(material_id);
            let tid = self.get_texture_id("__mega_heim");
            Self::emit_draw_call(self, material, tid, clip_rect, index_count as u32, base_vertex);
        } else {
            // Per-path rendering: each path gets its own transform and draw call.
            for path in &model.paths {
                let mut path_verts: Vec<Vertex> = model.vertices[path.vertex_range.clone()].to_vec();
                // Apply local transform (translate, rotate, scale) in SVG space.
                if path.local_transform.scale != 1.0 || path.local_transform.rotation != 0.0 || path.local_transform.translate != [0.0, 0.0] {
                    let s = path.local_transform.scale;
                    let rad = path.local_transform.rotation.to_radians();
                    let c = rad.cos();
                    let sn = rad.sin();
                    let tx = path.local_transform.translate[0];
                    let ty = path.local_transform.translate[1];
                    for v in &mut path_verts {
                        let px = v.position[0] * s;
                        let py = v.position[1] * s;
                        v.position[0] = px * c - py * sn + tx;
                        v.position[1] = px * sn + py * c + ty;
                    }
                }
                // Apply animations targeting this path.
                for anim in &model.animations {
                    if anim.target_id == path.id {
                        let effective_time = self.current_scene.time + animation_time_offset;
                        let t = (effective_time % anim.duration) / anim.duration;
                        let val = anim.from_val + (anim.to_val - anim.from_val) * t;
                        if anim.attribute_name == "transform" {
                            let mut min_x = f32::MAX; let mut min_y = f32::MAX;
                            let mut max_x = f32::MIN; let mut max_y = f32::MIN;
                            for v in &path_verts {
                                min_x = min_x.min(v.position[0]);
                                min_y = min_y.min(v.position[1]);
                                max_x = max_x.max(v.position[0]);
                                max_y = max_y.max(v.position[1]);
                            }
                            let cx = (min_x + max_x) * 0.5;
                            let cy = (min_y + max_y) * 0.5;
                            let c = val.to_radians().cos();
                            let s = val.to_radians().sin();
                            for v in &mut path_verts {
                                let dx = v.position[0] - cx;
                                let dy = v.position[1] - cy;
                                v.position[0] = cx + dx * c - dy * s;
                                v.position[1] = cy + dx * s + dy * c;
                            }
                        } else if anim.attribute_name == "opacity" {
                            for v in &mut path_verts { v.color[3] = val; }
                        } else if anim.attribute_name == "stroke-dashoffset" {
                            for v in &mut path_verts { v.slice[3] = 1.0 - val; }
                        }
                    }
                }
                // Position into output rect.
                Self::position_vertices(&mut path_verts, model.view_box, rect, material_id, clip, snap);
                let base_vertex = self.vertices.len() as u32;
                let index_start = self.indices.len();
                self.vertices.extend(path_verts);
                // Remap indices for this path's vertex offset.
                let path_index_start = path.index_range.start;
                for idx in &model.indices[path.index_range.clone()] {
                    self.indices.push(base_vertex + *idx - path_index_start as u32);
                }
                let index_count = path.index_range.len() as u32;
                let material = Self::resolve_material(material_id);
                let tid = self.get_texture_id("__mega_heim");
                Self::emit_draw_call(self, material, tid, clip_rect, index_count, base_vertex);
            }
        }
    }

    /// Helper: resolve material_id to DrawMaterial.
    fn resolve_material(material_id: u32) -> cvkg_core::DrawMaterial {
        match material_id {
            7 => cvkg_core::DrawMaterial::Glass {
                blur_radius: 20.0,
                ior_override: 0.0,
            },
            0 => cvkg_core::DrawMaterial::Opaque,
            _ => cvkg_core::DrawMaterial::TopUI,
        }
    }

    /// Helper: position vertices from SVG view_box into output rect.
    fn position_vertices(
        vertices: &mut [Vertex],
        view_box: Rect,
        rect: Rect,
        material_id: u32,
        clip: [f32; 4],
        snap: impl Fn(f32) -> f32,
    ) {
        for v in vertices.iter_mut() {
            let rel_x = (v.position[0] - view_box.x) / view_box.width;
            let rel_y = (v.position[1] - view_box.y) / view_box.height;
            v.position[0] = snap(rect.x + rel_x * rect.width);
            v.position[1] = snap(rect.y + rel_y * rect.height);
            v.position[2] = 0.0; // z will be set by transform stack
            v.logical = [v.position[0], v.position[1]];
            v.clip = clip;
            v.material_id = material_id;
        }
    }

    /// Helper: emit a draw call for a batch of vertices.
    fn emit_draw_call(
        renderer: &mut SurtrRenderer,
        material: cvkg_core::DrawMaterial,
        texture_id: Option<u32>,
        scissor_rect: Rect,
        index_count: u32,
        base_vertex: u32,
    ) {
        let (translation, scale_transform, rotation, _, _) = renderer.current_transform();
        let current_instance_data = InstanceData {
            translation,
            scale: scale_transform,
            rotation,
            blur_radius: 0.0,
            ior_override: 0.0,
        };
        let last_call = renderer.draw_calls.last();
        let needs_new_call = renderer.draw_calls.is_empty()
            || renderer.current_texture_id != texture_id
            || last_call.unwrap().scissor_rect != renderer.clip_stack.last().copied()
            || last_call.unwrap().material != material
            || renderer.instance_data.last() != Some(&current_instance_data);

        if needs_new_call {
            renderer.current_texture_id = texture_id;
            renderer.instance_data.push(current_instance_data);
            renderer.draw_calls.push(DrawCall {
                target_id: None,
                texture_id,
                scissor_rect: renderer.clip_stack.last().copied(),
                index_start: (renderer.indices.len() - index_count as usize) as u32,
                index_count,
                material,
                instance_start: (renderer.instance_data.len() - 1) as u32,
            });
        } else if let Some(call) = renderer.draw_calls.last_mut() {
            call.index_count += index_count;
        }
    }

    /// forge_headless — Initializes Surtr without a window for visual regression testing.
    pub async fn forge_headless(width: u32, height: u32) -> Self {
        let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
            backends: wgpu::Backends::all(),
            flags: wgpu::InstanceFlags::default(),
            backend_options: wgpu::BackendOptions::default(),
            display: None,
            memory_budget_thresholds: wgpu::MemoryBudgetThresholds::default(),
        });

        // Request adapter with robust multi-stage fallback for Bumblebee/Optimus compatibility
        log::info!("[GPU] Requesting HighPerformance adapter (headless)...");
        let mut adapter = instance
            .request_adapter(&wgpu::RequestAdapterOptions {
                power_preference: wgpu::PowerPreference::HighPerformance,
                compatible_surface: None,
                force_fallback_adapter: false,
            })
            .await
            .ok();

        if adapter.is_none() {
            log::warn!(
                "[GPU] HighPerformance adapter failed (possible Bumblebee/Optimus), trying LowPower..."
            );
            adapter = instance
                .request_adapter(&wgpu::RequestAdapterOptions {
                    power_preference: wgpu::PowerPreference::LowPower,
                    compatible_surface: None,
                    force_fallback_adapter: false,
                })
                .await
                .ok();
        }

        if adapter.is_none() {
            log::warn!("[GPU] Hardware adapters failed, trying Software fallback...");
            adapter = instance
                .request_adapter(&wgpu::RequestAdapterOptions {
                    power_preference: wgpu::PowerPreference::LowPower,
                    compatible_surface: None,
                    force_fallback_adapter: true,
                })
                .await
                .ok();
        }

        let adapter = adapter.expect("Failed to find a suitable GPU for Surtr");
        let info = adapter.get_info();
        log::info!(
            "[GPU] Selected adapter: {} ({:?}) on backend: {:?}",
            info.name,
            info.device_type,
            info.backend
        );
        log::info!("[GPU] Driver info: {} - {}", info.driver, info.driver_info);
        let required_features = adapter.features()
            & (wgpu::Features::TIMESTAMP_QUERY
                | wgpu::Features::SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING
                | wgpu::Features::TEXTURE_BINDING_ARRAY);

        let (device, queue) = adapter
            .request_device(&wgpu::DeviceDescriptor {
                label: Some("Surtr Headless Forge"),
                required_features,
                required_limits: wgpu::Limits {
                    max_bindings_per_bind_group: adapter
                        .limits()
                        .max_bindings_per_bind_group
                        .min(256),
                    max_binding_array_elements_per_shader_stage: adapter
                        .limits()
                        .max_binding_array_elements_per_shader_stage
                        .min(256),
                    ..wgpu::Limits::default()
                },
                memory_hints: wgpu::MemoryHints::default(),
                experimental_features: wgpu::ExperimentalFeatures::disabled(),
                trace: wgpu::Trace::Off,
            })
            .await
            .expect("Failed to create Surtr device");

        let instance = Arc::new(instance);
        let adapter = Arc::new(adapter);

        device.on_uncaptured_error(Arc::new(|error| {
            log::error!(
                "[GPU] Uncaptured device error (Device Lost or Panic): {:?}",
                error
            );
        }));

        let device = Arc::new(device);
        let queue = Arc::new(queue);

        Self::forge_internal(
            instance,
            adapter,
            device,
            queue,
            None,
            Some((width, height, wgpu::TextureFormat::Rgba8UnormSrgb)),
        )
        .await
    }

    /// capture_frame — Read back the rendered frame as a byte buffer (RGBA8).
    pub async fn capture_frame(&self) -> Result<Vec<u8>, String> {
        let ctx = self
            .headless_context
            .as_ref()
            .ok_or("Headless context required for capture")?;
        let current_width = self.current_width();
        let current_height = self.current_height();

        let u32_size = std::mem::size_of::<u32>() as u32;
        let width = ctx.width;
        let height = ctx.height;
        let bytes_per_row = width * u32_size;
        let padding = (256 - (bytes_per_row % 256)) % 256;
        let padded_bytes_per_row = bytes_per_row + padding;

        let output_buffer = self.device.create_buffer(&wgpu::BufferDescriptor {
            label: Some("Capture Buffer"),
            size: (padded_bytes_per_row as u64 * height as u64),
            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
            mapped_at_creation: false,
        });

        let mut encoder = self
            .device
            .create_command_encoder(&wgpu::CommandEncoderDescriptor {
                label: Some("Capture Encoder"),
            });

        encoder.copy_texture_to_buffer(
            wgpu::TexelCopyTextureInfo {
                texture: &ctx.output_texture,
                mip_level: 0,
                origin: wgpu::Origin3d::ZERO,
                aspect: wgpu::TextureAspect::All,
            },
            wgpu::TexelCopyBufferInfo {
                buffer: &output_buffer,
                layout: wgpu::TexelCopyBufferLayout {
                    offset: 0,
                    bytes_per_row: Some(padded_bytes_per_row),
                    rows_per_image: Some(height),
                },
            },
            wgpu::Extent3d {
                width,
                height,
                depth_or_array_layers: 1,
            },
        );

        self.queue.submit(Some(encoder.finish()));

        let buffer_slice = output_buffer.slice(..);
        let (sender, receiver) = futures::channel::oneshot::channel();
        buffer_slice.map_async(wgpu::MapMode::Read, move |v| {
            let _ = sender.send(v);
        });

        let _ = self.device.poll(wgpu::PollType::Wait {
            submission_index: None,
            timeout: None,
        });

        if let Ok(Ok(_)) = receiver.await {
            let data = buffer_slice.get_mapped_range();
            let mut result = Vec::with_capacity((width * height * 4) as usize);

            for y in 0..height {
                let start = (y * padded_bytes_per_row) as usize;
                let end = start + bytes_per_row as usize;
                result.extend_from_slice(&data[start..end]);
            }

            log::trace!(
                "[GPU] capture_frame: data len={}, first 4 bytes={:?}",
                data.len(),
                &data[0..4.min(data.len())]
            );

            drop(data);
            output_buffer.unmap();
            Ok(result)
        } else {
            Err("Failed to capture frame".to_string())
        }
    }

    pub(crate) fn current_width(&self) -> u32 {
        if let Some(id) = self.current_window {
            self.surfaces.get(&id).map(|s| s.config.width).unwrap_or(1)
        } else {
            self.headless_context.as_ref().map(|h| h.width).unwrap_or(1)
        }
    }

    pub(crate) fn current_height(&self) -> u32 {
        if let Some(id) = self.current_window {
            self.surfaces.get(&id).map(|s| s.config.height).unwrap_or(1)
        } else {
            self.headless_context
                .as_ref()
                .map(|h| h.height)
                .unwrap_or(1)
        }
    }

    pub(crate) fn current_scale_factor(&self) -> f32 {
        if let Some(id) = self.current_window {
            self.surfaces
                .get(&id)
                .map(|s| s.scale_factor)
                .unwrap_or(1.0)
        } else {
            self.headless_context
                .as_ref()
                .map(|h| h.scale_factor)
                .unwrap_or(1.0)
        }
    }

    /// Returns the elapsed time in seconds since the renderer was created.
    /// Used by shaders for time-based animations (volumetric, particles, etc.).
    pub(crate) fn current_time(&self) -> f32 {
        self.start_time.elapsed().as_secs_f32()
    }

    /// Find a filter by ID in the SVG tree's filter list.
    pub(crate) fn find_filter<'a>(
        tree: &'a usvg::Tree,
        filter_id: &str,
    ) -> Option<&'a usvg::filter::Filter> {
        tree.filters()
            .iter()
            .find(|f| f.id() == filter_id)
            .map(|arc| arc.as_ref())
    }
}

#[cfg(test)]
mod wgsl_tests {
    #[test]
    fn test_wgsl() {
        let source = include_str!("shaders/effects.wgsl");
        let mut frontend = naga::front::wgsl::Frontend::new();
        match frontend.parse(source) {
            Ok(_) => println!("WGSL parsed successfully!"),
            Err(e) => {
                panic!("WGSL parsing failed: \n{}", e.emit_to_string(source));
            }
        }
    }
}