diff --git a/app.js b/app.js
index 1436ab9..c8cfb25 100644
--- a/app.js
+++ b/app.js
@@ -149,12 +149,25 @@ uniform float iTime;
 uniform float iTimeDelta;
 uniform int iFrame;
 uniform vec4 iMouse;
+uniform vec4 iDate;
 ${userCode}
 void main() {
   mainImage(outColor, gl_FragCoord.xy);
 }`;
 }
 
+function setIDateUniform(gl, loc) {
+  if (loc == null) return;
+  const d = new Date();
+  gl.uniform4f(
+    loc,
+    d.getFullYear(),
+    d.getMonth() + 1,
+    d.getDate(),
+    d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds() + d.getMilliseconds() * 0.001
+  );
+}
+
 function createQuad(gl) {
   const quad = new Float32Array([-1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1]);
   const vao = gl.createVertexArray();
@@ -169,20 +182,30 @@ function createQuad(gl) {
 }
 
 function compileProgram(gl, fragmentShaderSource) {
-  function compile(type, source) {
+  function compile(type, label, source) {
+    if (gl.isContextLost?.()) {
+      throw new Error(`${label}: WebGL context lost`);
+    }
     const shader = gl.createShader(type);
     gl.shaderSource(shader, source);
     gl.compileShader(shader);
     if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
-      const info = gl.getShaderInfoLog(shader);
+      let info = (gl.getShaderInfoLog(shader) || "").trim();
+      if (!info) {
+        const err = gl.getError();
+        info =
+          err && err !== gl.NO_ERROR
+            ? `WebGL getError 0x${err.toString(16)} (driver returned no compile log)`
+            : "No compile log (often: shader too complex, loop/unroll limits, or driver bug).";
+      }
       gl.deleteShader(shader);
-      throw new Error(info || "unknown compile error");
+      throw new Error(`${label} shader:\n${info}`);
     }
     return shader;
   }
 
-  const vs = compile(gl.VERTEX_SHADER, vertexShaderSource);
-  const fs = compile(gl.FRAGMENT_SHADER, fragmentShaderSource);
+  const vs = compile(gl.VERTEX_SHADER, "Vertex", vertexShaderSource);
+  const fs = compile(gl.FRAGMENT_SHADER, "Fragment", fragmentShaderSource);
   const program = gl.createProgram();
   gl.attachShader(program, vs);
   gl.attachShader(program, fs);
@@ -190,9 +213,16 @@ function compileProgram(gl, fragmentShaderSource) {
   gl.deleteShader(vs);
   gl.deleteShader(fs);
   if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
-    const info = gl.getProgramInfoLog(program);
+    let info = (gl.getProgramInfoLog(program) || "").trim();
+    if (!info) {
+      const err = gl.getError();
+      info =
+        err && err !== gl.NO_ERROR
+          ? `WebGL getError 0x${err.toString(16)} (no link log)`
+          : "No link log (vertex/fragment interface mismatch or resource limits).";
+    }
     gl.deleteProgram(program);
-    throw new Error(info || "unknown link error");
+    throw new Error(`Program link:\n${info}`);
   }
   return program;
 }
@@ -260,6 +290,7 @@ function createPreviewCard(name, code) {
     iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
     iFrame: gl.getUniformLocation(program, "iFrame"),
     iMouse: gl.getUniformLocation(program, "iMouse"),
+    iDate: gl.getUniformLocation(program, "iDate"),
   };
 
   const state = {
@@ -366,6 +397,7 @@ function openDetail(previewState) {
     iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
     iFrame: gl.getUniformLocation(program, "iFrame"),
     iMouse: gl.getUniformLocation(program, "iMouse"),
+    iDate: gl.getUniformLocation(program, "iDate"),
   };
 
   detailRuntime = {
@@ -424,6 +456,7 @@ function renderAll(ts) {
     gl.uniform1f(uniforms.iTime, preview.localTime);
     gl.uniform1f(uniforms.iTimeDelta, preview.isPlaying && !paused ? localDt : 0);
     gl.uniform1i(uniforms.iFrame, preview.localFrame);
+    setIDateUniform(gl, uniforms.iDate);
     gl.uniform4f(
       uniforms.iMouse,
       mouse.x,
@@ -452,6 +485,7 @@ function renderAll(ts) {
     gl.uniform1f(uniforms.iTime, elapsed);
     gl.uniform1f(uniforms.iTimeDelta, dt);
     gl.uniform1i(uniforms.iFrame, frame);
+    setIDateUniform(gl, uniforms.iDate);
     gl.uniform4f(
       uniforms.iMouse,
       mouse.x,
diff --git a/display.js b/display.js
index e25758a..f71b6fe 100644
--- a/display.js
+++ b/display.js
@@ -106,6 +106,7 @@ uniform float iTime;
 uniform float iTimeDelta;
 uniform int iFrame;
 uniform vec4 iMouse;
+uniform vec4 iDate;
 uniform sampler2D iChannel0;
 uniform sampler2D iChannel1;
 uniform sampler2D iChannel2;
@@ -114,6 +115,18 @@ ${userCode}
 void main() { mainImage(outColor, gl_FragCoord.xy); }`;
 }
 
+function setIDateUniform(gl, loc) {
+  if (loc == null) return;
+  const d = new Date();
+  gl.uniform4f(
+    loc,
+    d.getFullYear(),
+    d.getMonth() + 1,
+    d.getDate(),
+    d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds() + d.getMilliseconds() * 0.001
+  );
+}
+
 function createQuad(gl) {
   const quad = new Float32Array([-1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, 1]);
   const vao = gl.createVertexArray();
@@ -128,19 +141,29 @@ function createQuad(gl) {
 }
 
 function compileProgram(gl, fragmentShaderSource) {
-  function compile(type, source) {
+  function compile(type, label, source) {
+    if (gl.isContextLost?.()) {
+      throw new Error(`${label}: WebGL context lost`);
+    }
     const shader = gl.createShader(type);
     gl.shaderSource(shader, source);
     gl.compileShader(shader);
     if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
-      const info = gl.getShaderInfoLog(shader);
+      let info = (gl.getShaderInfoLog(shader) || "").trim();
+      if (!info) {
+        const err = gl.getError();
+        info =
+          err && err !== gl.NO_ERROR
+            ? `WebGL getError 0x${err.toString(16)} (driver returned no compile log)`
+            : "No compile log (often: shader too complex, loop/unroll limits, or driver bug). Try a simpler shader.";
+      }
       gl.deleteShader(shader);
-      throw new Error(info || "unknown compile error");
+      throw new Error(`${label} shader:\n${info}`);
     }
     return shader;
   }
-  const vs = compile(gl.VERTEX_SHADER, vertexShaderSource);
-  const fs = compile(gl.FRAGMENT_SHADER, fragmentShaderSource);
+  const vs = compile(gl.VERTEX_SHADER, "Vertex", vertexShaderSource);
+  const fs = compile(gl.FRAGMENT_SHADER, "Fragment", fragmentShaderSource);
   const program = gl.createProgram();
   gl.attachShader(program, vs);
   gl.attachShader(program, fs);
@@ -148,9 +171,16 @@ function compileProgram(gl, fragmentShaderSource) {
   gl.deleteShader(vs);
   gl.deleteShader(fs);
   if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
-    const info = gl.getProgramInfoLog(program);
+    let info = (gl.getProgramInfoLog(program) || "").trim();
+    if (!info) {
+      const err = gl.getError();
+      info =
+        err && err !== gl.NO_ERROR
+          ? `WebGL getError 0x${err.toString(16)} (no link log)`
+          : "No link log (vertex/fragment interface mismatch or resource limits).";
+    }
     gl.deleteProgram(program);
-    throw new Error(info || "unknown link error");
+    throw new Error(`Program link:\n${info}`);
   }
   return program;
 }
@@ -349,6 +379,7 @@ function ensurePreviewWebGL(state) {
     iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
     iFrame: gl.getUniformLocation(program, "iFrame"),
     iMouse: gl.getUniformLocation(program, "iMouse"),
+    iDate: gl.getUniformLocation(program, "iDate"),
   };
   state.gl = gl;
   state.program = program;
@@ -611,6 +642,7 @@ function openDetail(previewState) {
       iTimeDelta: gl.getUniformLocation(program, "iTimeDelta"),
       iFrame: gl.getUniformLocation(program, "iFrame"),
       iMouse: gl.getUniformLocation(program, "iMouse"),
+      iDate: gl.getUniformLocation(program, "iDate"),
     },
     mouse: { x: 0, y: 0, downX: 0, downY: 0, down: false },
     _layoutW: 0,
@@ -741,6 +773,7 @@ function renderAll(ts) {
       gl.uniform1f(uniforms.iTimeDelta, 0);
       gl.uniform1i(uniforms.iFrame, 0);
     }
+    setIDateUniform(gl, uniforms.iDate);
     gl.uniform4f(
       uniforms.iMouse,
       mouse.x,
@@ -776,6 +809,7 @@ function renderAll(ts) {
     gl.uniform1f(uniforms.iTime, elapsed);
     gl.uniform1f(uniforms.iTimeDelta, dt);
     gl.uniform1i(uniforms.iFrame, frame);
+    setIDateUniform(gl, uniforms.iDate);
     gl.uniform4f(
       uniforms.iMouse,
       mouse.x,