diff --git a/crates/oak-plugin/src/clip.rs b/crates/oak-plugin/src/clip.rs
index 08859cb09..69d09f483 100644
--- a/crates/oak-plugin/src/clip.rs
+++ b/crates/oak-plugin/src/clip.rs
@@ -112,6 +112,15 @@ impl ClipInstance {
 				),
 			);
 		}
+		// OfxImageClipPropConnected（ofxsImageEffect.cpp:1106 的
+		// `Clip::isConnected()` 是无默认值强读——缺这个属性时，CImg 这类
+		// 带可选 mask clip 的插件直接抛
+		// PropertyUnknownToHost → MissingHostFeature 紫帧）。默认 0
+		// （未连接），挂接输入纹理时由 set_input_texture 置 1。
+		props.set_one(
+			crate::host::PROP_CLIP_CONNECTED,
+			crate::property::Value::Int(0),
+		);
 		Self {
 			props,
 			name,
@@ -166,6 +175,14 @@ impl ClipInstance {
 	/// 挂接输入纹理（oaknode 侧 clip 输入值变化时由 param/render 桥
 	/// 调用）。`time` 用于多帧纹理选择。None 断开。
 	pub fn set_input_texture(&self, texture: Option<crate::render::Texture>, _time: f64) {
+		// The connection state follows the texture hand-off (the render
+		// driver only feeds clips that have input; optional mask clips
+		// stay 0, so `Clip::isConnected()` answers false for them).
+		let connected = i32::from(texture.is_some());
+		self.props.set_one(
+			crate::host::PROP_CLIP_CONNECTED,
+			crate::property::Value::Int(connected),
+		);
 		*self.input_texture.lock().unwrap_or_else(|e| e.into_inner()) = texture;
 	}
 
diff --git a/crates/oak-plugin/src/image.rs b/crates/oak-plugin/src/image.rs
index e14a94b41..d23921021 100644
--- a/crates/oak-plugin/src/image.rs
+++ b/crates/oak-plugin/src/image.rs
@@ -207,6 +207,38 @@ impl Image {
 			K_IMAGE_PROP_UNIQUE_ID,
 			vec![Value::String(unique_identifier())],
 		);
+		// OfxPropType="OfxTypeImage"：图像实例的类型标识（支持库
+		// validateImageBaseProperties 的必备项，带可校验默认值）。
+		img.props.define(
+			"OfxPropType",
+			vec![Value::String(std::ffi::CString::new("OfxTypeImage").unwrap())],
+		);
+		// OFX 必备图像属性（支持库 ImageBase/Image 构造的无默认值强读；
+		// 缺失即抛 PropertyUnknownToHost → MissingHostFeature 紫帧）：
+		// 方形像素 1.0；预乘声明（本管线按预乘 alpha 处理）；无场。
+		img.props.define(
+			"OfxImagePropPixelAspectRatio",
+			vec![Value::Double(1.0)],
+		);
+		img.props.define(
+			"OfxImageEffectPropPreMultiplication",
+			// kOfxImagePreMultiplied 的真实字符串值是
+			// "OfxImageAlphaPremultiplied"（ofxImageEffect.h），
+			// ofxs mapStrToPreMultiplicationEnum 只认这三个精确值。
+			vec![Value::String(
+				std::ffi::CString::new("OfxImageAlphaPremultiplied").unwrap(),
+			)],
+		);
+		img.props.define(
+			"OfxImagePropField",
+			vec![Value::String(std::ffi::CString::new("OfxFieldNone").unwrap())],
+		);
+		// OfxImageEffectPropRenderScale：openfx-misc 的
+		// checkBadRenderScaleOrField 用它比对渲染参数（1:1）。
+		img.props.define(
+			"OfxImageEffectPropRenderScale",
+			vec![Value::Double(1.0), Value::Double(1.0)],
+		);
 
 		img
 	}
diff --git a/crates/oak-plugin/src/instance.rs b/crates/oak-plugin/src/instance.rs
index 4e3c59fd7..a0e9c8779 100644
--- a/crates/oak-plugin/src/instance.rs
+++ b/crates/oak-plugin/src/instance.rs
@@ -264,6 +264,10 @@ impl Instance {
 			crate::suites::tag::INSTANCE,
 		);
 		let empty = PropertySet::new();
+		Self::add_action_arg_compat_props(&empty);
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[probe-args] getClipPreferences in_args {:p} out {:p}", &empty, &out);
+		}
 		let stat = unsafe {
 			self.plugin
 				.call_action(ACTION_GET_CLIP_PREFERENCES, inst_handle, &empty, &out)
@@ -360,6 +364,10 @@ impl Instance {
 			PROP_RENDER_SCALE,
 			vec![Value::Double(scale.x), Value::Double(scale.y)],
 		);
+		Self::add_action_arg_compat_props(&in_args);
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[probe-args] getRod in_args {:p}", &in_args);
+		}
 		// out args 预定义（HS 行为：宿主先建属性表，插件只管写——
 		// 缺失属性上插件的 propSet 会失败被忽略）。
 		let out = PropertySet::new();
@@ -407,6 +415,10 @@ impl Instance {
 			PROP_RENDER_SCALE,
 			vec![Value::Double(scale.x), Value::Double(scale.y)],
 		);
+		Self::add_action_arg_compat_props(&in_args);
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[probe-args] getRoi in_args {:p}", &in_args);
+		}
 		in_args.define(
 			PROP_ROI,
 			vec![
@@ -454,6 +466,19 @@ impl Instance {
 	}
 
 	/// isIdentity action：返回 Some((time, input_clip_name)) 表示本帧
+	/// OFX 1.4+/Natron 框架对 action in-args 的强读属性：缺了会被抛成
+	/// PropertyUnknownToHost → MissingHostFeature（紫帧根因）。每个
+	/// action in-args 都带上。
+	fn add_action_arg_compat_props(in_args: &PropertySet) {
+		use crate::property::Value;
+		// NatronOfxPropNativeOverlays：Natron 支持库强读（0 = 宿主不
+		// 支持原生 overlay，插件走自己的回退）。OfxImageEffectPropRenderPlanes
+		// 不放 in-args：Natron 框架按**字符串**读它，存在但类型是 Int
+		// 反而会抛 PropertyUnknownToHost（缺失它才容忍）——它只属于
+		// 图像/clip 属性（OFX 1.4 语义在 clipGetImagePlane 一侧）。
+		in_args.set_one("NatronOfxPropNativeOverlays", Value::Int(0));
+	}
+
 	/// 直接透传该输入 clip；None 表示需要真正 render。
 	///
 	/// 参照 HS: ofxhImageEffect.cpp:1378-1450：in args = time + scale +
@@ -475,16 +500,17 @@ impl Instance {
 		in_args.define(
 			PROP_RENDER_WINDOW,
 			vec![
-				Value::Double(0.0),
-				Value::Double(0.0),
-				Value::Double(0.0),
-				Value::Double(0.0),
+				Value::Int(0),
+				Value::Int(0),
+				Value::Int(0),
+				Value::Int(0),
 			],
 		);
 		in_args.set_one(
 			PROP_FIELD_TO_RENDER,
-			Value::String(CString::new("OfxImageFieldBoth").unwrap()),
+			Value::String(CString::new("OfxFieldNone").unwrap()),
 		);
+		in_args.set_one("NatronOfxPropNativeOverlays", Value::Int(0));
 		// out args 预定义：IsIdentity（String）+ Time（Double）。
 		let out = PropertySet::new();
 		out.set_one(PROP_IS_IDENTITY, Value::String(CString::new("").unwrap()));
@@ -494,14 +520,23 @@ impl Instance {
 			&self.props as *const PropertySet,
 			crate::suites::tag::INSTANCE,
 		);
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[ofx] isIdentity in_args {:p} out_args {:p}", &in_args, &out);
+		}
 		let stat = unsafe {
 			self.plugin
 				.call_action(ACTION_IS_IDENTITY, inst_handle, &in_args, &out)
 		};
 		if stat != crate::suites::status::OK && stat != crate::suites::status::REPLY_DEFAULT {
-			return Err(crate::error::Error::Failed(format!(
-				"isIdentity 失败：{stat}"
-			)));
+			// A failed isIdentity is NOT fatal: the C++ plugin renderer
+			// never calls this action at all (plugins that error on it —
+			// the CImg suite answers MissingHostFeature — simply render
+			// normally). Treat any non-OK as "not identity" and let the
+			// real render decide.
+			if std::env::var_os("OAK_OFX_TRACE").is_some() {
+				eprintln!("[ofx] isIdentity stat {stat}: proceeding to render");
+			}
+			return Ok(None);
 		}
 		let identity = out.get(PROP_IS_IDENTITY, 0);
 		match identity {
@@ -541,23 +576,29 @@ impl Instance {
 			PROP_RENDER_SCALE,
 			vec![Value::Double(scale.x), Value::Double(scale.y)],
 		);
+		// RenderWindow 必须是 Int x4（支持库 ofxsPropertyValidation 对
+		// render in-args 的强制类型；像素坐标本就是整型——Double 会校验
+		// 失败成 kOfxStatFailed）。
 		in_args.define(
 			PROP_RENDER_WINDOW,
 			vec![
-				Value::Double(window.x1),
-				Value::Double(window.y1),
-				Value::Double(window.x2),
-				Value::Double(window.y2),
+				Value::Int(window.x1.round() as i32),
+				Value::Int(window.y1.round() as i32),
+				Value::Int(window.x2.round() as i32),
+				Value::Int(window.y2.round() as i32),
 			],
 		);
 		in_args.set_one(
 			PROP_FIELD_TO_RENDER,
-			Value::String(CString::new("OfxImageFieldBoth").unwrap()),
+			Value::String(CString::new("OfxFieldNone").unwrap()),
 		);
 		in_args.set_one(PROP_SEQUENTIAL_RENDER, Value::Int(0));
 		in_args.set_one(PROP_INTERACTIVE_RENDER, Value::Int(0));
 		in_args.set_one(PROP_RENDER_QUALITY_DRAFT, Value::Int(0));
 		in_args.set_one(PROP_NO_SPATIAL_AWARENESS, Value::Int(0));
+		// Natron 支持库对 NatronOfxPropNativeOverlays 的强读（0 = 宿主
+		// 不支持原生 overlay——插件据此走自己的回退路径）。
+		in_args.set_one("NatronOfxPropNativeOverlays", Value::Int(0));
 		if gl_enabled {
 			in_args.set_one(crate::host::PROP_GL_ENABLED, Value::Int(1));
 		}
diff --git a/crates/oak-plugin/src/node_factory.rs b/crates/oak-plugin/src/node_factory.rs
index 5c30686c9..e03e9e01d 100644
--- a/crates/oak-plugin/src/node_factory.rs
+++ b/crates/oak-plugin/src/node_factory.rs
@@ -899,7 +899,11 @@ fn execute_plugin_job(
 		effect_input_id: effect_input_id.clone(),
 		inputs: inputs.clone(),
 		values: pod_values,
-		renderer: None,
+		// GL 渲染路径：OpenGL-only 插件（CImg 套件）在 CPU 路径的
+		// isIdentity 直接回 kOfxStatErrMissingHostFeature（紫帧根因）。
+		// 标记上下文只服务于 use_opengl 的 kind 判定；真正的 GL 渲染走
+		// gl_bridge 的离屏上下文（无头的 oak-worker 进程同样可用）。
+		renderer: Some(std::sync::Arc::new(crate::render::GlKindMarker)),
 		clear_destination: false,
 		interactive: false,
 	};
@@ -1129,6 +1133,76 @@ mod tests {
 		assert!(shared_plugin_instance("com.example.definitely-missing").is_none());
 	}
 
+	/// 最简单的真实插件（AddOFX：每个像素加一个常量）经 executor
+	/// 路径渲染成功——区分"系统性宿主问题"与"单插件问题"（机器上
+	/// 没装该插件则跳过）。
+	#[test]
+	fn add_plugin_renders_through_the_executor() {
+		render_real_plugin_smoke("net.sf.openfx.AddPlugin");
+	}
+
+	/// 真实 GL-only 插件（CImg 的 ChromaKeyerOFX）经 executor 路径渲染
+	/// 成功——GL-kind 标记必须把它引上可用的 GL 路径，而不是
+	/// MissingHostFeature 紫帧（机器上没装该插件则跳过）。
+	#[test]
+	fn cimg_chromakeyer_renders_through_the_executor() {
+		render_real_plugin_smoke("net.sf.openfx.ChromaKeyerPlugin");
+	}
+
+	fn render_real_plugin_smoke(identifier: &str) {
+		let host = crate::host::Host::global();
+		let _ = host.cache.scan();
+		if host.cache.find(identifier).is_none() {
+			eprintln!("{identifier} not installed; skipping");
+			return;
+		}
+		install_render_executor();
+		let instance = shared_plugin_instance(identifier)
+			.expect("the shared instance factory resolves the plugin");
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			let inst = instance_from_id(instance).expect("registered");
+			let props = &inst.value.plugin.descriptor.props;
+			props.with_locked(|all| {
+				for p in all.iter().filter(|p| p.name.contains("GL") || p.name.contains("OpenGL")) {
+					eprintln!("[probe] desc prop {} = {:?}", p.name, p.values);
+				}
+			});
+		}
+
+		// 8x8 不透明绿帧（典型 keyer 输入）。
+		let mut frame = oak_render::eval::generate_frame(
+			oak_core::Rational::new(0, 1),
+			(8, 8),
+			oak_core::PixelFormat::F32,
+		)
+		.unwrap();
+		for px in frame.data.chunks_exact_mut(16) {
+			for (c, v) in px.chunks_exact_mut(4).zip([0.1f32, 0.9, 0.1, 1.0]) {
+				c.copy_from_slice(&v.to_le_bytes());
+			}
+		}
+		let spec = oak_render::eval::JobSpec::Plugin {
+			instance,
+			time: 0.0,
+			effect_input_id: Some("Source".to_string()),
+			inputs: Vec::new(),
+			values: Vec::new(),
+		};
+		let out = execute_plugin_job(&oak_render::eval::PluginJobRequest {
+			spec: &spec,
+			src: oak_render::texture::Texture::wrap_frame(frame),
+		})
+		.expect("the GL-capable render succeeds (no MissingHostFeature purple)");
+		let oak_render::texture::Texture::Cpu(out_frame) = &out else {
+			panic!("a CPU frame comes back");
+		};
+		let mut px = [0f32; 4];
+		for i in 0..4 {
+			px[i] = f32::from_le_bytes(out_frame.data[i * 4..i * 4 + 4].try_into().unwrap());
+		}
+		assert_ne!(px, [1.0, 0.0, 1.0, 1.0], "must not be the purple failure frame");
+	}
+
 	/// 构造一个只含 push-button 参数的最小实例（直接登记进注册表）。
 	fn instance_with_push_button() -> u64 {
 		use std::ffi::{c_char, c_void};
diff --git a/crates/oak-plugin/src/param.rs b/crates/oak-plugin/src/param.rs
index d968142b3..a8670920c 100644
--- a/crates/oak-plugin/src/param.rs
+++ b/crates/oak-plugin/src/param.rs
@@ -442,8 +442,13 @@ impl ParamDef {
 				props.set_one(P_STRING_FILE_EXISTS, Value::Int(1));
 			}
 			TYPE_CHOICE => {
-				// 维度 0：选项数由插件 SetN 决定。
+				// 维度 0：选项数由插件 SetN 决定。ChoiceEnum（枚举值映射）
+				// 与 ChoiceLabelOption（OFX 1.5 按值标签）同样预定义空
+				// 数组——新支持库读它们时不是"未知属性"（其强读会抛成
+				// PropertyUnknownToHost → MissingHostFeature）。
 				props.define(P_CHOICE_OPTION, vec![]);
+				props.define("OfxParamPropChoiceEnum", vec![]);
+				props.define("OfxParamPropChoiceLabelOption", vec![]);
 			}
 			TYPE_CUSTOM => {
 				props.set_one(P_CUSTOM_INTERP, Value::Pointer(std::ptr::null_mut()));
diff --git a/crates/oak-plugin/src/render.rs b/crates/oak-plugin/src/render.rs
index dd3e32d9d..6c27ec003 100644
--- a/crates/oak-plugin/src/render.rs
+++ b/crates/oak-plugin/src/render.rs
@@ -144,6 +144,37 @@ pub fn renderer_is_open_gl(renderer: &Renderer) -> bool {
 	renderer.kind() == oak_render::backend::BackendKind::Gl
 }
 
+/// A GL-kind marker context for [`RenderJob::renderer`]. The field's only
+/// consumer is the use_opengl decision's kind check
+/// ([`renderer_is_open_gl`]); the actual GL work (offscreen context, FBO,
+/// readback) goes through [`crate::gl_bridge`], which needs no renderer
+/// object. Passing this marker flips OpenGL-requiring plugins (the CImg
+/// suite, which answers `kOfxStatErrMissingHostFeature` on the CPU path)
+/// onto the real GL path in any process — including the headless
+/// oak-worker, where gl_bridge creates its own offscreen context.
+pub struct GlKindMarker;
+
+impl oak_render::backend::GpuContextLike for GlKindMarker {
+	fn kind(&self) -> oak_render::backend::BackendKind {
+		oak_render::backend::BackendKind::Gl
+	}
+	fn destroy_texture(&self, _token: u64) {}
+	fn upload(&self, _token: u64, _frame: &oak_render::texture::Frame) -> oak_render::error::Result<()> {
+		Ok(())
+	}
+	fn download(&self, _token: u64) -> oak_render::error::Result<oak_render::texture::Frame> {
+		Ok(oak_render::texture::Frame::new())
+	}
+	fn blit(
+		&self,
+		_src: u64,
+		_dst: u64,
+		_processor: Option<&oak_render::color::ColorProcessor>,
+	) -> oak_render::error::Result<()> {
+		Ok(())
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;
diff --git a/crates/oak-plugin/src/render_driver.rs b/crates/oak-plugin/src/render_driver.rs
index a18ae2ead..85683f9dd 100644
--- a/crates/oak-plugin/src/render_driver.rs
+++ b/crates/oak-plugin/src/render_driver.rs
@@ -171,6 +171,16 @@ pub fn render_frame(
 				crate::suites::gl_render::pick_gl_pixel_depth(&inst.plugin.descriptor.props)
 					.is_some();
 			let gl_name_ok = crate::gl_bridge::gl_available();
+			if std::env::var_os("OAK_OFX_TRACE").is_some() {
+				let raw = inst
+					.plugin
+					.descriptor
+					.props
+					.get(crate::host::PROP_GL_RENDER_SUPPORTED, 0);
+				eprintln!(
+					"[ofx] use_opengl decision: plugin_gl={plugin_gl} depth_ok={depth_ok} gl_available={gl_name_ok} (raw GL prop: {raw:?})"
+				);
+			}
 			plugin_gl && depth_ok && gl_name_ok
 		}
 		_ => false,
@@ -203,6 +213,9 @@ pub fn render_frame(
 
 	// 4. getClipPreferences（pluginrenderer.cpp:1554-1594）。
 	let prefs = inst.get_clip_preferences()?;
+	if std::env::var_os("OAK_OFX_TRACE").is_some() {
+		eprintln!("[ofx] clip prefs: components={} (inst {})", prefs.output_components, inst.plugin.identifier);
+	}
 	let components = match prefs.output_components.as_str() {
 		"OfxImageComponentRGBA" => crate::image::Components::Rgba,
 		"OfxImageComponentRGB" => crate::image::Components::Rgb,
diff --git a/crates/oak-plugin/src/suites/gl_render.rs b/crates/oak-plugin/src/suites/gl_render.rs
index adae14a01..8ec68c55c 100644
--- a/crates/oak-plugin/src/suites/gl_render.rs
+++ b/crates/oak-plugin/src/suites/gl_render.rs
@@ -318,7 +318,7 @@ fn make_texture_props(
 	rect_props(&props, crate::image::K_IMAGE_PROP_BOUNDS, bounds);
 	rect_props(&props, crate::image::K_IMAGE_PROP_ROD, bounds);
 	props.set_one(crate::image::K_IMAGE_PROP_ROW_BYTES, Value::Int(row_bytes));
-	props.set_one("OfxImagePropField", Value::String(cs("OfxImageFieldNone")));
+	props.set_one("OfxImagePropField", Value::String(cs("OfxFieldNone")));
 	props.set_one(
 		crate::image::K_IMAGE_PROP_UNIQUE_ID,
 		Value::String(crate::image::unique_identifier()),
diff --git a/crates/oak-plugin/src/suites/image_effect.rs b/crates/oak-plugin/src/suites/image_effect.rs
index 56e68ea1d..2f6202fe6 100644
--- a/crates/oak-plugin/src/suites/image_effect.rs
+++ b/crates/oak-plugin/src/suites/image_effect.rs
@@ -100,6 +100,9 @@ fn caught(f: impl FnOnce() -> Result<(), c_int>) -> c_int {
 	if code != status::OK && std::env::var_os("OAK_OFX_TRACE").is_some() {
 		eprintln!("[ofx] image-effect suite error {code} at {caller}");
 	}
+	if std::env::var_os("OAK_OFX_TRACE").is_some() {
+		eprintln!("[ofx] image-effect suite call at {caller} -> {code}");
+	}
 	code
 }
 
diff --git a/crates/oak-plugin/src/suites/param.rs b/crates/oak-plugin/src/suites/param.rs
index 9f2bc524e..2e9e991ab 100644
--- a/crates/oak-plugin/src/suites/param.rs
+++ b/crates/oak-plugin/src/suites/param.rs
@@ -160,8 +160,10 @@ fn caught(f: impl FnOnce() -> Result<(), c_int>) -> c_int {
 		|_| status::FAILED,
 		|r| r.map_or_else(|c| c, |()| status::OK),
 	);
-	if code != status::OK && std::env::var_os("OAK_OFX_TRACE").is_some() {
-		eprintln!("[ofx] param suite error {code} at {caller}");
+	if std::env::var_os("OAK_OFX_TRACE").is_some() {
+		if code != status::OK {
+			eprintln!("[ofx] param suite error {code} at {caller}");
+		}
 	}
 	code
 }
diff --git a/crates/oak-plugin/src/suites/property.rs b/crates/oak-plugin/src/suites/property.rs
index 4644322ba..99774a851 100644
--- a/crates/oak-plugin/src/suites/property.rs
+++ b/crates/oak-plugin/src/suites/property.rs
@@ -130,7 +130,8 @@ unsafe fn caught(handle: *mut c_void, f: impl FnOnce(&PropertySet) -> Result<(),
 	}))
 	.unwrap_or(status::FAILED);
 	if code != status::OK && std::env::var_os("OAK_OFX_TRACE").is_some() {
-		eprintln!("[ofx] property suite error {code} at {caller}");
+		let tag = crate::suites::tag::kind(handle);
+		eprintln!("[ofx] property suite error {code} at {caller} (handle {handle:p} tag {tag})");
 	}
 	code
 }
@@ -185,7 +186,13 @@ fn get_value_inner<'a>(
 	// 固定类型，等价）。空数组没有类型探针，跳过类型检查，越界
 	// 由下面的索引访问报 BadIndex（HS getValueRaw 语义）。
 	if let Some(probe) = p.values.first() {
-		if Kind::of(probe) != kind {
+		// Int <-> Double 数值协随（与 get_n 同款宽容宿主语义）。
+		let numeric = matches!(Kind::of(probe), Kind::Int | Kind::Double)
+			&& matches!(kind, Kind::Int | Kind::Double);
+		if Kind::of(probe) != kind && !numeric {
+			if std::env::var_os("OAK_OFX_TRACE").is_some() {
+				eprintln!("[ofx] property kind mismatch: {name}");
+			}
 			return Err(status::ERR_UNKNOWN);
 		}
 	}
@@ -481,11 +488,11 @@ unsafe extern "C" fn prop_get_string(
 			}
 			let r = get_string(set, name, index);
 			if std::env::var_os("OAK_OFX_TRACE").is_some() {
-				let status = match &r {
-					Ok(_) => 0,
-					Err(c) => *c,
+				let rendered = match &r {
+					Ok(p) => format!("0 <- {:?}", unsafe { std::ffi::CStr::from_ptr(*p) }),
+					Err(c) => format!("{c}"),
 				};
-				eprintln!("[ofx] propGetString(h={handle:p}, {name}[{index}]) -> {status}");
+				eprintln!("[ofx] propGetString(h={handle:p}, {name}[{index}]) -> {rendered}");
 			}
 			*out = r?;
 			Ok(())
@@ -511,6 +518,11 @@ unsafe extern "C" fn prop_get_double(
 					*out = d;
 					Ok(())
 				}
+				// Int <-> Double 数值协随（宽容宿主语义，同 get_n）。
+				Value::Int(i) => {
+					*out = i as f64;
+					Ok(())
+				}
 				_ => Err(status::FAILED),
 			}
 		})
@@ -535,6 +547,11 @@ unsafe extern "C" fn prop_get_int(
 					*out = i;
 					Ok(())
 				}
+				// Int <-> Double 数值协随（宽容宿主语义，同 get_n）。
+				Value::Double(d) => {
+					*out = d as i32;
+					Ok(())
+				}
 				_ => Err(status::FAILED),
 			}
 			.map_err(|c| {
@@ -564,15 +581,33 @@ fn get_n(
 			.find(|p| p.name == name)
 			.ok_or(status::ERR_UNKNOWN)?;
 		let probe = p.values.first().ok_or(status::ERR_UNKNOWN)?;
-		if Kind::of(probe) != kind {
+		// Int <-> Double coercion (forgiving-host semantics): the CImg
+		// framework reads the DOUBLE render window with propGetIntN and
+		// must still get the values; strict kind checks turn that into a
+		// bogus MissingHostFeature at render time.
+		let numeric = matches!(Kind::of(probe), Kind::Int | Kind::Double)
+			&& matches!(kind, Kind::Int | Kind::Double);
+		if Kind::of(probe) != kind && !numeric {
 			return Err(status::ERR_UNKNOWN);
 		}
 		let n = idx(count)?.min(p.values.len());
 		for (i, v) in p.values.iter().take(n).enumerate() {
 			write(v, i);
 		}
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[ofx] propGetN({name} x{n}) -> ok");
+		}
 		Ok(())
 	})
+	.map_err(|code| {
+		// The property the plugin asked for and we did not have — the
+		// single most useful line when a plugin reports
+		// MissingHostFeature (trace-gated, like fetchSuite misses).
+		if std::env::var_os("OAK_OFX_TRACE").is_some() {
+			eprintln!("[ofx] property miss: {name} (code {code})");
+		}
+		code
+	})
 }
 
 unsafe extern "C" fn prop_get_pointer_n(
@@ -629,6 +664,7 @@ unsafe extern "C" fn prop_get_double_n(
 			}
 			get_n(set, name, count, Kind::Double, |v, i| match v {
 				Value::Double(d) => *out.add(i) = *d,
+				Value::Int(d) => *out.add(i) = *d as f64,
 				_ => {}
 			})
 		})
@@ -649,6 +685,7 @@ unsafe extern "C" fn prop_get_int_n(
 			}
 			get_n(set, name, count, Kind::Int, |v, i| match v {
 				Value::Int(d) => *out.add(i) = *d,
+				Value::Double(d) => *out.add(i) = *d as i32,
 				_ => {}
 			})
 		})
@@ -685,6 +722,10 @@ unsafe extern "C" fn prop_get_dimension(
 			// 已定义的空数组（如协商属性的初始状态）是合法维度 0，不是错误。
 			let exists = set.with_locked(|props| props.iter().any(|p| p.name == name));
 			if !exists {
+				if std::env::var_os("OAK_OFX_TRACE").is_some() {
+					let tag = crate::suites::tag::kind(handle);
+					eprintln!("[ofx] property miss (dimension): {name} (handle {handle:p} tag {tag})");
+				}
 				return Err(status::ERR_UNKNOWN);
 			}
 			*out = set.dimension(name) as c_int;