From 0c2225bdbbaa4b9caaa68f03116ed6f6fa83dcf2 Mon Sep 17 00:00:00 2001
From: Admin <admin@viaeon.com>
Date: Fri, 17 Jul 2026 10:24:41 +0000
Subject: [PATCH] fix: handle dynamic dimensions in Math output shape

---
 internal/captcha/handler.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/internal/captcha/handler.go b/internal/captcha/handler.go
index 390c72e..7f49d7d 100644
--- a/internal/captcha/handler.go
+++ b/internal/captcha/handler.go
@@ -343,10 +343,31 @@ func preprocessMath(img image.Image) ([]float32, error) {
 func decodeMath(output []float32, outputShape []int64) string {
 	// 输出格式: [num_chars, batch, timesteps] = [51, 1, 19]
 	// 需要转置为 [batch, timesteps, num_chars] = [1, 19, 51]
+	if len(outputShape) < 3 || len(output) == 0 {
+		return ""
+	}
+
 	numChars := int(outputShape[0])  // 51
 	batch := int(outputShape[1])     // 1
 	timesteps := int(outputShape[2]) // 19
 
+	// 处理动态维度（可能返回 -1）
+	if numChars <= 0 {
+		numChars = 51 // 默认字符数
+	}
+	if batch <= 0 {
+		batch = 1
+	}
+	if timesteps <= 0 {
+		// 从输出大小推断
+		timesteps = len(output) / (numChars * batch)
+	}
+
+	// 边界检查
+	if numChars <= 0 || batch <= 0 || timesteps <= 0 {
+		return ""
+	}
+
 	// 转置: output[c*batch*t + b*t + t] -> transposed[b*timesteps*numChars + t*numChars + c]
 	transposed := make([]float32, batch*timesteps*numChars)
 	for b := 0; b < batch; b++ {