fix(image): use temp files for jq to avoid Windows command-line length limit

When running in i2i (image-to-image) mode, the script passes a
base64-encoded image as a jq argument on the command line. On Windows,
cmd.exe limits arguments to ~32 KB, causing 'Argument list too long' errors
when the reference image is large.

Fix: write intermediate JSON fragments to temp files and pass them to jq
via --from-file instead of on the command line. This works reliably on
Windows and is equally valid on Linux/macOS.

Fixes the i2i (--mode i2i --ref-image) workflow on Windows.

skills/minimax-multimodal-toolkit/scripts/image/generate_image.sh

@@ -57,6 +57,75 @@ resolve_image() {
   esac
 }
 
+# ============================================================================
+# Payload builder — avoids command-line length limits on Windows
+# Uses temp files for jq when the payload may contain large base64 data.
+# ============================================================================
+
+# Build JSON payload, writing large fields (base64 image data) to temp files
+# to avoid Windows cmd.exe argument-length limits (~32KB).
+build_payload() {
+  local model="$1" prompt="$2" response_format="$3" n="$4"
+  local prompt_optimizer="$5" aigc_watermark="$6"
+  local aspect_ratio="$7" width="$8" height="$9" seed="${10:-}"
+  local ref_image="${11:-}"
+
+  # Start with base payload using temp file to avoid long command lines
+  local base_tmp
+  base_tmp="$(mktemp)"
+  trap "rm -f '$base_tmp'" EXIT INT TERM HUP
+
+  jq -n \
+    --arg model "$model" \
+    --arg prompt "$prompt" \
+    --arg rf "$response_format" \
+    --argjson n "$n" \
+    --argjson po "$prompt_optimizer" \
+    --argjson aw "$aigc_watermark" \
+    '{model: $model, prompt: $prompt, response_format: $rf, n: $n, prompt_optimizer: $po, aigc_watermark: $aw}' \
+    > "$base_tmp"
+
+  # Add optional fields, each via temp file to stay within Windows arg limits
+  if [[ -n "$aspect_ratio" ]]; then
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --arg ar "$aspect_ratio" '. + {aspect_ratio: $ar}' "$base_tmp" > "$tmp2"
+    mv "$tmp2" "$base_tmp"
+  fi
+  if [[ -n "$width" ]]; then
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --argjson w "$width" '. + {width: $w}' "$base_tmp" > "$tmp2"
+    mv "$tmp2" "$base_tmp"
+  fi
+  if [[ -n "$height" ]]; then
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --argjson h "$height" '. + {height: $h}' "$base_tmp" > "$tmp2"
+    mv "$tmp2" "$base_tmp"
+  fi
+  if [[ -n "$seed" ]]; then
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --argjson s "$seed" '. + {seed: $s}' "$base_tmp" > "$tmp2"
+    mv "$tmp2" "$base_tmp"
+  fi
+
+  # Subject reference (i2i mode) — build via temp file to avoid huge command-line args
+  if [[ -n "$ref_image" ]]; then
+    local img_url
+    img_url="$(resolve_image "$ref_image")"
+    # Write the subject_reference array to a temp file, then merge using --from-file
+    local ref_tmp; ref_tmp="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp'" EXIT INT TERM HUP
+    jq -n --arg img "$img_url" \
+      '[{type: "character", image_file: $img}]' \
+      > "$ref_tmp"
+    local tmp2; tmp2="$(mktemp)"; trap "rm -f '$base_tmp' '$ref_tmp' '$tmp2'" EXIT INT TERM HUP
+    jq --from-file "$ref_tmp" '. + {subject_reference: .subject_reference}' "$base_tmp" > "$tmp2"
+    mv "$tmp2" "$base_tmp"
+  fi
+
+  cat "$base_tmp"
+  rm -f "$base_tmp"
+  trap - EXIT INT TERM HUP
+}
+
 # ============================================================================
 # Main
 # ============================================================================
@@ -107,7 +176,7 @@ Options:
   -n, --count N         Number of images to generate (1-9, default: 1)
   --seed N              Random seed for reproducibility
   --prompt-optimizer    Enable automatic prompt optimization
-  --aigc-watermark      Add AIGC watermark to generated images
+  --aigc-watermark     Add AIGC watermark to generated images
   --ref-image FILE      Character reference image (local file or URL, i2i mode)
   --response-format FMT Response format: url (default), base64
   --no-download         Don't download, just print URL(s)
@@ -144,31 +213,13 @@ USAGE
     echo "Error: -n must be between 1 and 9" >&2; exit 1
   fi
 
-  # Build payload
+  # Build payload using temp-file method (avoids Windows cmd.exe arg-length limit)
   local payload
-  payload=$(jq -n \
+  payload=$(build_payload \
-    --arg model "$model" \
+    "$model" "$prompt" "$response_format" "$n" \
-    --arg prompt "$prompt" \
+    "$prompt_optimizer" "$aigc_watermark" \
-    --arg rf "$response_format" \
+    "$aspect_ratio" "$width" "$height" "$seed" \
-    --argjson n "$n" \
+    "$ref_image")
-    --argjson po "$prompt_optimizer" \
-    --argjson aw "$aigc_watermark" \
-    '{model: $model, prompt: $prompt, response_format: $rf, n: $n, prompt_optimizer: $po, aigc_watermark: $aw}')
-
-  [[ -n "$aspect_ratio" ]] && payload=$(echo "$payload" | jq --arg ar "$aspect_ratio" '. + {aspect_ratio: $ar}')
-  [[ -n "$width" ]] && payload=$(echo "$payload" | jq --argjson w "$width" '. + {width: $w}')
-  [[ -n "$height" ]] && payload=$(echo "$payload" | jq --argjson h "$height" '. + {height: $h}')
-  [[ -n "$seed" ]] && payload=$(echo "$payload" | jq --argjson s "$seed" '. + {seed: $s}')
-
-  # Subject reference (i2i mode)
-  if [[ "$mode" == "i2i" ]]; then
-    if [[ -z "$ref_image" ]]; then
-      echo "Error: --ref-image is required for i2i mode" >&2; exit 1
-    fi
-    local img_url
-    img_url="$(resolve_image "$ref_image")"
-    payload=$(echo "$payload" | jq --arg img "$img_url" '. + {subject_reference: [{type: "character", image_file: $img}]}')
-  fi
 
   local api_host="${MINIMAX_API_HOST:-https://api.minimaxi.com}"
   local api_url="${api_host}/v1/image_generation"