fix(ai-outfit): per-resolution timeout + _to_int default fallback

- §8 dynamic timeout: add resolution_timeout() (512/1K/2K/4K ->
  180/240/360/600s); generate() uses it for the POST and image download.
  timeout_seconds now defaults to 0 = auto-by-resolution; an explicit
  positive value overrides. Validation allows 0, rejects negatives.
- _to_int now returns the supplied default on parse failure (was 0), so a
  bad connect_timeout_seconds falls back to 30 instead of failing as 0.
- Tests: +5 (resolution map, auto vs override timeout, connect fallback).
- tasks.md §19.1/§19.2: tick unit-test item, note runner is pure-logic.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/services/ai_image_service.py

@@ -28,6 +28,16 @@ SUPPORTED_API_TYPES = {
 _BASE64_KEYS = {"image_base64", "base64", "b64_json", "data"}
 _IMAGE_EXTENSIONS = {".png", ".jpg", ".jpeg", ".webp", ".gif"}
 
+# Default read timeout (seconds) per output resolution (docs/11-ai-outfit.md §8).
+# Higher resolutions take longer to generate; a fixed timeout_seconds in the
+# model config overrides this mapping.
+RESOLUTION_TIMEOUTS = {"512": 180, "1K": 240, "2K": 360, "4K": 600}
+
+
+def resolution_timeout(resolution, default=240):
+    """Return the default read timeout in seconds for *resolution*."""
+    return RESOLUTION_TIMEOUTS.get(str(resolution).strip().upper(), default)
+
 
 class AiImageServiceError(RuntimeError):
     """Base error for AI image generation service failures."""
@@ -45,7 +55,7 @@ class AiModelConfig:
     model: str
     api_key: str
     api_type: str = API_AUTO
-    timeout_seconds: int = 240
+    timeout_seconds: int = 0          # 0 = 按分辨率自动（resolution_timeout）
     connect_timeout_seconds: int = 30
     extra_body: Any = field(default_factory=dict)
 
@@ -58,7 +68,7 @@ class AiModelConfig:
             model=str(data.get("model", "") or ""),
             api_key=str(data.get("api_key", "") or ""),
             api_type=str(data.get("api_type", API_AUTO) or API_AUTO),
-            timeout_seconds=_to_int(data.get("timeout_seconds", 240), 240),
+            timeout_seconds=_parse_optional_timeout(data.get("timeout_seconds")),
             connect_timeout_seconds=_to_int(data.get("connect_timeout_seconds", 30), 30),
             extra_body=data.get("extra_body") or {},
         )
@@ -84,7 +94,7 @@ def api_config_errors(config):
         errors.append("缺少 api_key")
     if cfg.api_type not in SUPPORTED_API_TYPES:
         errors.append("api_type 不支持: {}".format(cfg.api_type))
-    if cfg.timeout_seconds <= 0:
+    if cfg.timeout_seconds < 0:   # 0 = 按分辨率自动；负数 = 解析失败/非法
         errors.append("timeout_seconds 必须大于 0")
     if cfg.connect_timeout_seconds <= 0:
         errors.append("connect_timeout_seconds 必须大于 0")
@@ -285,7 +295,12 @@ class ImageApiClient:
             url = url.replace("{model}", self.config.model)
 
         headers = {"Authorization": "Bearer {}".format(self.config.api_key)}
-        timeout = (self.config.connect_timeout_seconds, self.config.timeout_seconds)
+        read_timeout = (
+            self.config.timeout_seconds
+            if self.config.timeout_seconds > 0
+            else resolution_timeout(resolution)
+        )
+        timeout = (self.config.connect_timeout_seconds, read_timeout)
 
         if api_type == API_IMAGES_EDITS:
             data, files = build_multipart_fields(self.config, prompt, image_path, resolution)
@@ -310,7 +325,7 @@ class ImageApiClient:
         image_bytes = extract_image_from_response(
             payload,
             session=self.session,
-            timeout=self.config.timeout_seconds,
+            timeout=read_timeout,
         )
         if not image_bytes:
             raise AiImageServiceError("AI 响应中未找到图片")
@@ -327,7 +342,21 @@ def _to_int(value, default):
     try:
         return int(value or default)
     except (TypeError, ValueError):
+        return default
+
+
+def _parse_optional_timeout(value):
+    """Parse an optional read timeout.
+
+    Absent/blank -> 0 (auto by resolution); an explicit positive value overrides
+    the per-resolution default; an unparseable value -> -1 so validation flags it.
+    """
+    if value is None or value == "":
         return 0
+    try:
+        return int(value)
+    except (TypeError, ValueError):
+        return -1
 
 
 def _join_url(base_url, suffix):