diff --git a/modules/engine-graphics/src/rhi_shadow_bridge_tests.zig b/modules/engine-graphics/src/rhi_shadow_bridge_tests.zig
new file mode 100644
index 00000000..240e09d0
--- /dev/null
+++ b/modules/engine-graphics/src/rhi_shadow_bridge_tests.zig
@@ -0,0 +1,126 @@
+const std = @import("std");
+const testing = std.testing;
+const rhi = @import("engine-rhi").rhi;
+const Mat4 = @import("engine-math").Mat4;
+const validateCascades = @import("engine-shadows").validateCascades;
+const ShadowCascades = @import("engine-shadows").ShadowCascades;
+const CASCADE_COUNT = @import("engine-shadows").CASCADE_COUNT;
+
+const rhi_shadow_bridge = @import("vulkan/rhi_shadow_bridge.zig");
+
+test "validateCascades returns true for valid cascades" {
+    var cascades = ShadowCascades.initZero();
+    cascades.cascade_splits = .{ 10.0, 50.0, 150.0, 500.0 };
+    cascades.texel_sizes = .{ 0.5, 1.0, 2.0, 4.0 };
+    cascades.light_space_matrices = .{Mat4.identity} ** CASCADE_COUNT;
+
+    const MockLogScope = struct {
+        var warn_called: bool = false;
+        fn warn(_: @TypeOf(@as(u32, 0)), comptime _: []const u8, _: anytype) void {
+            warn_called = true;
+        }
+    };
+
+    MockLogScope.warn_called = false;
+    const result = validateCascades(cascades, MockLogScope{ .unused = 0 });
+    try testing.expect(result);
+    try testing.expect(!MockLogScope.warn_called);
+}
+
+test "validateCascades returns false and logs for invalid cascades" {
+    var cascades = ShadowCascades.initZero();
+    cascades.cascade_splits = .{ 10.0, std.math.nan(f32), 150.0, 500.0 };
+    cascades.texel_sizes = .{ 0.5, 1.0, 2.0, 4.0 };
+    cascades.light_space_matrices = .{Mat4.identity} ** CASCADE_COUNT;
+
+    const MockLogScope = struct {
+        var warn_count: u32 = 0;
+        fn warn(_: @TypeOf(@as(u32, 0)), comptime _: []const u8, _: anytype) void {
+            warn_count += 1;
+        }
+    };
+
+    MockLogScope.warn_count = 0;
+    const result = validateCascades(cascades, MockLogScope{ .unused = 0 });
+    try testing.expect(!result);
+    try testing.expect(MockLogScope.warn_count > 0);
+}
+
+test "ShadowParams resolution defaults to 4096" {
+    const params = rhi.ShadowParams{
+        .light_space_matrices = .{Mat4.identity} ** rhi.SHADOW_CASCADE_COUNT,
+        .cascade_splits = .{ 10.0, 50.0, 150.0, 500.0 },
+        .shadow_texel_sizes = .{ 0.5, 1.0, 2.0, 4.0 },
+    };
+
+    try testing.expectEqual(@as(u32, 4096), params.resolution);
+}
+
+test "ShadowParams shadow_texel_sizes accessible via real field" {
+    const params = rhi.ShadowParams{
+        .light_space_matrices = .{Mat4.identity} ** rhi.SHADOW_CASCADE_COUNT,
+        .cascade_splits = .{ 10.0, 50.0, 150.0, 500.0 },
+        .shadow_texel_sizes = .{ 0.125, 0.25, 0.5, 1.0 },
+        .resolution = 2048,
+    };
+
+    try testing.expectEqual(@as(f32, 0.125), params.shadow_texel_sizes[0]);
+    try testing.expectEqual(@as(f32, 1.0), params.shadow_texel_sizes[3]);
+    try testing.expectEqual(@as(u32, 2048), params.resolution);
+}
+
+test "rhi_shadow_bridge getShadowMapHandle returns 0 for OOB cascade" {
+    const MockShadowRuntime = struct {
+        shadow_map_handles: [rhi.SHADOW_CASCADE_COUNT]rhi.TextureHandle = .{ 10, 20, 30, 40 },
+    };
+
+    const ctx = struct {
+        shadow_runtime: MockShadowRuntime,
+    }{ .shadow_runtime = .{} };
+
+    const handle = rhi_shadow_bridge.getShadowMapHandle(ctx, rhi.SHADOW_CASCADE_COUNT);
+    try testing.expectEqual(@as(rhi.TextureHandle, 0), handle);
+
+    const handle_plus_one = rhi_shadow_bridge.getShadowMapHandle(ctx, rhi.SHADOW_CASCADE_COUNT + 5);
+    try testing.expectEqual(@as(rhi.TextureHandle, 0), handle_plus_one);
+}
+
+test "rhi_shadow_bridge getShadowMapHandle returns valid handle for cascade 0..3" {
+    const MockShadowRuntime = struct {
+        shadow_map_handles: [rhi.SHADOW_CASCADE_COUNT]rhi.TextureHandle = .{ 100, 200, 300, 400 },
+    };
+
+    const ctx = struct {
+        shadow_runtime: MockShadowRuntime,
+    }{ .shadow_runtime = .{} };
+
+    try testing.expectEqual(@as(rhi.TextureHandle, 100), rhi_shadow_bridge.getShadowMapHandle(ctx, 0));
+    try testing.expectEqual(@as(rhi.TextureHandle, 200), rhi_shadow_bridge.getShadowMapHandle(ctx, 1));
+    try testing.expectEqual(@as(rhi.TextureHandle, 300), rhi_shadow_bridge.getShadowMapHandle(ctx, 2));
+    try testing.expectEqual(@as(rhi.TextureHandle, 400), rhi_shadow_bridge.getShadowMapHandle(ctx, 3));
+}
+
+test "ShadowUniforms extern struct size matches production layout" {
+    const ShadowUniforms = @import("vulkan/rhi_shadow_bridge.zig").ShadowUniforms;
+
+    const matrices_size = @sizeOf([rhi.SHADOW_CASCADE_COUNT]Mat4);
+    const splits_size = @sizeOf([4]f32);
+    const sizes_size = @sizeOf([4]f32);
+    const params_size = @sizeOf([4]f32);
+    const expected = matrices_size + splits_size + sizes_size + params_size;
+
+    try testing.expectEqual(@as(usize, expected), @sizeOf(ShadowUniforms));
+}
+
+test "ShadowUniforms field offsets are sequential for GPU upload" {
+    const ShadowUniforms = @import("vulkan/rhi_shadow_bridge.zig").ShadowUniforms;
+
+    const matrices_end = @sizeOf([rhi.SHADOW_CASCADE_COUNT]Mat4);
+    const splits_offset = @offsetOf(ShadowUniforms, "cascade_splits");
+    const sizes_offset = @offsetOf(ShadowUniforms, "shadow_texel_sizes");
+    const params_offset = @offsetOf(ShadowUniforms, "shadow_params");
+
+    try testing.expectEqual(matrices_end, splits_offset);
+    try testing.expectEqual(matrices_end + @sizeOf([4]f32), sizes_offset);
+    try testing.expectEqual(matrices_end + @sizeOf([4]f32) * 2, params_offset);
+}
diff --git a/modules/engine-graphics/src/root.zig b/modules/engine-graphics/src/root.zig
index 84a5419a..c55e1703 100644
--- a/modules/engine-graphics/src/root.zig
+++ b/modules/engine-graphics/src/root.zig
@@ -94,6 +94,7 @@ pub const VulkanDevice = vulkan_device.VulkanDevice;
 pub const VulkanContext = vulkan_rhi_context_types.VulkanContext;
 pub const VulkanSwapchain = vulkan_swapchain.VulkanSwapchain;
 pub const rhi_tests = @import("rhi_tests.zig");
+pub const rhi_shadow_bridge_tests = @import("rhi_shadow_bridge_tests.zig");
 pub const shadow_cascade_tests = @import("engine-shadows").shadow_cascade_tests;
 pub const shadow_tests = @import("shadow_tests.zig");
 pub const shadow_system_tests = @import("engine-shadows").shadow_system_tests;
diff --git a/src/tests.zig b/src/tests.zig
index 374fd1ce..9ae23709 100644
--- a/src/tests.zig
+++ b/src/tests.zig
@@ -47,6 +47,7 @@ test {
     _ = @import("engine-graphics").rhi_tests;
     _ = @import("engine-clouds").cloud_system;
     _ = @import("engine-shadows").shadow_cascade_tests;
+    _ = @import("engine-graphics").rhi_shadow_bridge_tests;
     _ = @import("engine-graphics").shadow_tests;
     _ = @import("engine-shadows").shadow_system_tests;
     _ = @import("engine-math").utils_tests;