diff --git a/README.md b/README.md
index 3682bfe..e8bccb3 100644
--- a/README.md
+++ b/README.md
@@ -55,36 +55,47 @@ AI 调用后，stdout 输出网页正文（text/html/markdown 三种格式），
 | exit 1 | 失败 | 致命错误（所有实例不可用、参数错误等） |
 | exit 2 | 空结果 | 搜索成功但无结果 |
 
-**错误处理**：`--format json` 模式下，错误以 JSON 输出到 stdout（非 stderr），格式为 `{"error": "...", "error_code": "E_NETWORK", "exit_code": 1, "query": "..."}`，AI 可程序化捕获。
+**错误处理**：`--format json` 模式下，错误以 JSON 输出到 stdout（非 stderr），格式为 `{"error": "...", "error_code": "E_NETWORK", "recovery_hint": "...", "exit_code": 1, "query": "..."}`，AI 可程序化捕获并按 `recovery_hint` 采取恢复行动。
 
-**错误码体系**（`error_code` 字段）：
+**错误码体系**（`error_code` + `recovery_hint` 字段）：
 
-| 错误码 | 含义 | AI 恢复策略 |
-|--------|------|-------------|
-| `E_CONFIG` | 配置错误（无实例） | 提示用户设置 `-i` / `SEARXNG_INSTANCE` |
-| `E_AUTH` | 认证失败（401/403） | 检查 token/凭证 |
-| `E_NETWORK` | 网络错误（连接失败、5xx） | 重试或切换实例/代理 |
-| `E_RATE_LIMIT` | 限流（429） | 等待后重试 |
-| `E_PARSE` | 解析错误 | 检查实例 JSON 支持 |
-| `E_INPUT` | 输入错误（参数/文件） | 修正参数 |
-| `E_INTERNAL` | 内部错误 | 报告 bug |
+| 错误码 | 含义 | recovery_hint（节选） |
+|--------|------|----------------------|
+| `E_CONFIG` | 配置错误（无实例） | 设置 `-i`/`SEARXNG_INSTANCE`/配置文件 |
+| `E_AUTH` | 认证失败（401/403） | 检查凭证、token 过期与权限 |
+| `E_NETWORK` | 网络错误（连接失败、5xx） | 重试退避、切换实例、检查代理 |
+| `E_RATE_LIMIT` | 限流（429） | 等待重试、降低频率、分散负载 |
+| `E_PARSE` | 解析错误 | 切换实例、切换 `--method` |
+| `E_EMPTY` | 空结果（exit 2） | 调整查询词、扩大 `--time-range`/`--categories` |
+| `E_INPUT` | 输入错误（参数/文件） | 检查语法、标志组合、文件路径 |
+| `E_INTERNAL` | 内部错误 | 用 `--verbose` 重跑并报告 |
 
 ### 流式输出与进度事件（AI 高级用法）
 
 **`--stream`**：JSON Lines 流式输出，每条结果一行 JSON，AI 可增量处理：
 ```
 {"type": "result", "result": {"title": "...", "url": "..."}}
-{"type": "done", "count": 10, "query": "..."}
+{"type": "done", "schema_version": "1.0", "count": 10, "query": "..."}
 ```
+搜索失败时输出 error 事件（含 `recovery_hint`）：
+```
+{"type": "error", "error": "...", "error_code": "E_AUTH", "recovery_hint": "Verify credentials...", "query": "..."}
+```
+注意：`--stream` 仅在单查询 + `--format json` 下有效；与 `--queries-file` 或非 json 格式同用会立即报 `E_INPUT`。
 
 **`--progress`**：进度事件流（JSON Lines 到 stderr），AI 可实时跟踪执行：
 ```
 {"event": "start", "query": "...", "instances": 2}
+{"event": "instance_try", "url": "https://inst1.example.com", "attempt": 1}
+{"event": "instance_ok", "url": "https://inst1.example.com", "latency": 0.342, "results": 10}
+{"event": "instance_fail", "url": "https://inst2.example.com", "error": "HTTP 503", "error_code": "E_NETWORK"}
 {"event": "cache_hit", "query": "...", "ttl": 30}
 {"event": "fetch_ok", "url": "...", "chars": 12345}
 {"event": "done", "results": 10, "query": "..."}
 ```
 
+**`--dump-schema`**：输出当前版本的 JSON Schema 到 stdout 并退出，AI 可程序化发现字段名与类型，无需解析文档。
+
 ```bash
 # AI 推荐用法：流式输出 + 进度事件
 python scripts/search.py -q "research" -i https://your-instance --stream --progress
@@ -94,7 +105,7 @@ python scripts/search.py -q "research" -i https://your-instance --stream --progr
 
 ### 前置条件
 
-- Python 3.8+
+- Python 3.8+（3.11+ 开箱即用；3.8-3.10 使用 `searxng.toml` 配置需 `pip install tomli`）
 - 一个 SearXNG 实例 URL（自建或受信任的实例）
 
 ### 安装
@@ -105,9 +116,13 @@ git clone https://git.metona.cn/MetonaTeam/searxng-use-cli.git
 
 无需安装依赖。`search.py` 仅使用 Python 标准库，开箱即用。
 
-可选安装（提升 `fetch.py` 抓取质量）：
+可选安装：
 ```bash
+# 提升 fetch.py 抓取质量（HTTP 连接池 + HTML 解析）
 pip install requests beautifulsoup4
+
+# Python 3.8-3.10 使用 searxng.toml 配置文件时需要（3.11+ 内置 tomllib）
+pip install tomli
 ```
 
 ### 配置实例
@@ -248,10 +263,12 @@ python scripts/fetch.py -u https://example.com \
 **工程**
 - 共享 `common.py`（统一重试/字符集/认证/日志）
 - 结构化日志（`--verbose` / `--quiet`）
-- 结构化错误码（`E_NETWORK` / `E_AUTH` / `E_RATE_LIMIT` 等）
-- JSON Lines 流式输出（`--stream`）
-- 进度事件（`--progress`，JSON Lines 到 stderr）
-- 330 个单元+集成测试
+- 结构化错误码 + `recovery_hint` 恢复建议（`E_NETWORK` / `E_AUTH` / `E_RATE_LIMIT` 等）
+- JSON 输出含 `schema_version` 字段，`--dump-schema` 输出 JSON Schema 文档
+- JSON Lines 流式输出（`--stream`，含 `error` 事件类型）
+- 进度事件（`--progress`，含 `instance_try`/`instance_ok`/`instance_fail`，JSON Lines 到 stderr）
+- batch 模式统一 schema（`status` 字段区分成功/失败）
+- 352 个单元+集成测试
 
 ## 跨 Agent 兼容性
 
@@ -279,7 +296,7 @@ pip install pytest
 pytest -q
 ```
 
-330 个测试覆盖：缓存操作、认证解析、域名过滤、Markdown 转换、搜索逻辑、集成流程、日志配置、HTML 回退、自动抓取、健康检查、输出格式化、实例解析、并行搜索、CLI 端到端、错误码分类、流式输出、进度事件、配置文件认证。
+352 个测试覆盖：缓存操作、认证解析、域名过滤、Markdown 转换、搜索逻辑、集成流程、日志配置、HTML 回退、自动抓取、健康检查、输出格式化、实例解析、并行搜索、CLI 端到端、错误码分类、流式输出、进度事件、配置文件认证、schema_version、recovery_hint、batch 统一 schema、--dump-schema。
 
 ## 项目结构
 
diff --git a/SKILL.md b/SKILL.md
index 9906799..419e7b3 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -1,7 +1,7 @@
 ---
 name: searxng-use-cli
 description: Use when you need to search the web via your OWN SearXNG instance (no public-instance discovery). 3 CLI scripts + a shared common.py module — execute privacy-respecting searches against a user-supplied instance (with multi-instance failover, 5xx/429 retry, auto-fetch) or via SEARXNG_INSTANCE env / config file, fetch/extract readable text or markdown from web pages. Zero-config replacement for proprietary search APIs.
-version: 1.7.0
+version: 1.8.0
 author: Metona Team
 license: MIT
 platforms: [linux, macos, windows]
@@ -188,23 +188,24 @@ In `--format json` mode, errors are emitted as structured JSON on stdout:
 {
   "error": "All 2 instances failed. Last error: connection refused",
   "error_code": "E_NETWORK",
+  "recovery_hint": "Retry with backoff, or try a different SearXNG instance. Check network connectivity, proxy settings, and instance uptime.",
   "exit_code": 1,
   "query": "search term"
 }
 ```
 
-AI agents can use `error_code` to programmatically decide recovery strategy:
+AI agents can use `error_code` to programmatically decide recovery strategy, and `recovery_hint` for a ready-to-use actionable suggestion:
 
-| Code | Meaning | AI Recovery Strategy |
-|------|---------|---------------------|
-| `E_CONFIG` | Configuration error (no instance resolved) | Prompt user to set `-i` / `SEARXNG_INSTANCE` / config file |
-| `E_AUTH` | Authentication failed (401/403) | Check token/credentials, prompt user to re-authenticate |
-| `E_NETWORK` | Network error (connection refused, timeout, 5xx, all instances failed) | Retry with backoff, switch instance or proxy |
-| `E_RATE_LIMIT` | Rate limited (429) | Wait and retry with reduced frequency |
-| `E_PARSE` | Parse error (JSON/HTML parsing failed) | Check if instance supports JSON, try HTML fallback |
-| `E_EMPTY` | Empty results (exit code 2) | Adjust query terms or time range |
-| `E_INPUT` | Input error (bad parameters, file not found) | Fix CLI arguments or file paths |
-| `E_INTERNAL` | Internal error (unexpected exception) | Report bug with full error message |
+| Code | Meaning | recovery_hint (abridged) |
+|------|---------|--------------------------|
+| `E_CONFIG` | Configuration error (no instance resolved) | Provide `-i`/`SEARXNG_INSTANCE`/config file |
+| `E_AUTH` | Authentication failed (401/403) | Verify credentials, check token expiry & permissions |
+| `E_NETWORK` | Network error (connection refused, timeout, 5xx, all instances failed) | Retry with backoff, switch instance, check proxy |
+| `E_RATE_LIMIT` | Rate limited (429) | Wait and retry, reduce frequency, distribute load |
+| `E_PARSE` | Parse error (JSON/HTML parsing failed) | Try different instance, switch `--method` |
+| `E_EMPTY` | Empty results (exit code 2) | Refine query, broaden `--time-range`, add `--categories` |
+| `E_INPUT` | Input error (bad parameters, file not found) | Check query syntax, flag combinations, file paths |
+| `E_INTERNAL` | Internal error (unexpected exception) | Re-run with `--verbose`, report bug |
 
 ### JSON Lines Streaming (`--stream`)
 
@@ -221,14 +222,19 @@ Output format (each line is a separate JSON object):
 ```
 {"type": "result", "result": {"title": "...", "url": "...", "content": "..."}}
 {"type": "result", "result": {"title": "...", "url": "...", "content": "..."}}
-{"type": "done", "count": 2, "query": "large topic"}
+{"type": "done", "schema_version": "1.0", "count": 2, "query": "large topic"}
 ```
 
 - `type: "result"` — one per search result, emitted as soon as available
-- `type: "done"` — terminal event with total count, always emitted last
-- Exit code 0 on success, 2 on empty results (done event still emitted)
+- `type: "done"` — terminal event with total count and `schema_version`, always emitted last
+- `type: "error"` — emitted when the search fails, includes `error_code` and `recovery_hint`:
+  ```
+  {"type": "error", "error": "All 2 instances failed. Last error: HTTP Error 403", "error_code": "E_AUTH", "recovery_hint": "Verify credentials...", "query": "..."}
+  ```
+- Exit code 0 on success, 1 on error, 2 on empty results (done event still emitted)
 
-Only valid with `--format json` (the default).
+Only valid with `--format json` (single query mode). Using `--stream` with
+`--queries-file` or non-json formats raises `E_INPUT` immediately.
 
 ### Progress Events (`--progress`)
 
@@ -243,6 +249,9 @@ Event types (each on its own line, JSON Lines format on stderr):
 
 ```jsonl
 {"event": "start", "query": "research topic", "instances": 2}
+{"event": "instance_try", "url": "https://instance1.example.com", "attempt": 1}
+{"event": "instance_ok", "url": "https://instance1.example.com", "latency": 0.342, "results": 10}
+{"event": "instance_fail", "url": "https://instance2.example.com", "error": "HTTP 503", "error_code": "E_NETWORK"}
 {"event": "cache_hit", "query": "research topic", "ttl": 30}
 {"event": "cache_store", "query": "research topic", "ttl": 30}
 {"event": "fetch_start", "count": 3}
@@ -264,10 +273,19 @@ logs are human-readable text.
 
 ### Output JSON Schema
 
-The default `--format json` output shape (for reference, not enforced):
+The default `--format json` output includes a `schema_version` field so AI
+agents can detect breaking changes. Run `--dump-schema` to get the full JSON
+Schema document programmatically:
+
+```bash
+python scripts/search.py --dump-schema
+```
+
+Single query output shape:
 
 ```json
 {
+  "schema_version": "1.0",
   "query": "search term",
   "number_of_results": 10,
   "results": [
@@ -294,13 +312,28 @@ The default `--format json` output shape (for reference, not enforced):
       "text_length": 12345,
       "truncated": false,
       "final_url": "https://example.com/final",
-      "user_agent_used": "searxng-cli/1.7.0"
+      "user_agent_used": "searxng-cli/1.8.0"
     }
   ],
   "fetched_source": "json"
 }
 ```
 
+Batch mode (`--queries-file`) wraps results in a unified schema:
+
+```json
+{
+  "schema_version": "1.0",
+  "queries": [
+    {"query": "term1", "status": "ok", "results": {...}},
+    {"query": "term2", "status": "error", "error": "...", "error_code": "E_NETWORK"}
+  ]
+}
+```
+
+Each batch entry has a `status` field (`"ok"` or `"error"`). Successful entries
+contain `results`; failed entries contain `error` and `error_code`.
+
 Fields marked as optional may be absent. The `fetched` and `fetched_source`
 fields only appear when `--fetch N` is used.
 
@@ -431,7 +464,7 @@ usage: search.py [-h] [--query QUERY] [--instance URL]
                  [--exclude-domain DOMAINS] [--queries-file FILE]
                  [--cache-ttl MINUTES] [--clear-cache] [--cache-stats]
                  [--sort-by {score,date,engine,none}] [--no-dedup]
-                 [--config FILE] [--verbose] [--quiet] [--version]
+                 [--config FILE] [--dump-schema] [--verbose] [--quiet] [--version]
 ```
 
 **What it does:**
@@ -445,14 +478,14 @@ usage: search.py [-h] [--query QUERY] [--instance URL]
 8. **Stable auto-fetch:** `--fetch 3` concurrently downloads top 3 result pages with retry, browser-UA fallback, CAPTCHA detection, and **`fetch.py`'s higher-quality text extractor** (the same engine `fetch.py` uses)
 9. **Health-check mode:** `--verify` probes each instance (reachability / JSON-API support / latency / POST support / engine list / auth status) and prints a report, then exits without searching — use it to validate your instance list
 10. **Result caching:** `--cache-ttl 30` stores results for 30 min; identical queries within the TTL skip the network entirely. Cache lives at `$SEARXNG_CACHE_DIR` or `~/.cache/searxng-cli/cache.db` (SQLite, WAL mode). `--clear-cache` / `--cache-stats` manage it without searching
-11. **Batch mode:** `--queries-file FILE` reads one query per line (blank/`#` lines skipped) and runs them in sequence; output is a JSON array (or one block per query in brief/urls). A failed query is recorded but does not abort the batch
+11. **Batch mode:** `--queries-file FILE` reads one query per line (blank/`#` lines skipped) and runs them in sequence; JSON output is `{"schema_version": "1.0", "queries": [{"query":..., "status": "ok"|"error", ...}]}` (or one block per query in brief/urls). A failed query is recorded but does not abort the batch. Exit codes: 0 if any query returned results, 1 if all errored, 2 if all empty
 12. **Dedup + sort + domain filter:** After search (and cache), duplicate URLs are collapsed (default; `--no-dedup` disables), results are sorted (`--sort-by`; default: score descending), and then `--include-domain`/`--exclude-domain` filter by domain. Matching is case-insensitive and ignores a leading `www.`; when a domain is in both lists, exclude wins
 13. **Proxy & auth:** `--proxy URL` routes both search and fetch through a proxy; `--auth-bearer` / `--auth-basic` (plus `*-file` variants, `searxng.toml` `auth_basic`/`auth_bearer` fields, and `SEARXNG_BEARER_TOKEN` / `SEARXNG_BASIC_AUTH` env vars) supply credentials. Priority: CLI flag > file > config file > env var
 14. **Config defaults:** `searxng.toml` may pre-set most flags (engines, categories, language, safesearch, time_range, method, format, sort_by, timeout, max_retries, proxy, cache_ttl, fetch, fetch_timeout, fetch_retries, max_size, auth_basic, auth_bearer); explicit CLI flags always win
-15. **Structured errors:** in `--format json` mode, failures print a JSON object `{"error": "...", "exit_code": N, "query": "..."}` to stdout so agents can parse them
+15. **Structured errors:** in `--format json` mode, failures print a JSON object `{"error": "...", "error_code": "E_*", "recovery_hint": "...", "exit_code": N, "query": "..."}` to stdout so agents can parse them and decide recovery strategy
 
 **Key options:**
-- `--query "your search"` — **required unless** `--verify`, `--queries-file`, `--clear-cache`, or `--cache-stats` is used
+- `--query "your search"` — **required unless** `--verify`, `--queries-file`, `--clear-cache`, `--cache-stats`, or `--dump-schema` is used
 - `--instance https://searx.example.org` — **required unless** `SEARXNG_INSTANCE` env var or a config file supplies it; comma-separated list enables failover
 - `--queries-file FILE` — read queries from a file (one per line; blank/`#` skipped) and run them in sequence; overrides `--query`
 - `--engines google,duckduckgo` — restrict to specific search engines (whitespace around commas is auto-stripped; see default list above)
@@ -487,6 +520,7 @@ usage: search.py [-h] [--query QUERY] [--instance URL]
 - `--cache-ttl MINUTES` — cache results for N minutes (default: `0` = disabled); identical queries within the TTL skip the network
 - `--clear-cache` — delete all cached entries and exit (no search)
 - `--cache-stats` — print cache statistics (entries, age, size, path) and exit
+- `--dump-schema` — print the JSON Schema for `--format json` output and exit; lets AI agents programmatically discover field names and types without parsing prose docs
 - `--auth-bearer TOKEN` — `Authorization: Bearer` header for private instances
 - `--auth-bearer-file FILE` — read Bearer token from a file (first non-empty, non-`#` line); also honors `SEARXNG_BEARER_TOKEN` env var
 - `--auth-basic USER:PASS` — `Authorization: Basic` header (auto base64-encoded)
diff --git a/scripts/_config.py b/scripts/_config.py
index 1ac219e..42e1e65 100644
--- a/scripts/_config.py
+++ b/scripts/_config.py
@@ -1,11 +1,12 @@
 """Package-level constants for searxng-cli scripts.
 
 Import in sibling scripts with:
-    from _config import VERSION, USER_AGENT
+    from _config import VERSION, USER_AGENT, SCHEMA_VERSION
 
 Retry settings and shared HTTP utilities now live in ``common.py`` so that
 both ``search.py`` and ``fetch.py`` share one consistent implementation.
 """
 
-VERSION = "1.7.0"
+VERSION = "1.8.0"
+SCHEMA_VERSION = "1.0"
 USER_AGENT = f"searxng-cli/{VERSION}"
diff --git a/scripts/cache.py b/scripts/cache.py
index 6902c33..ae08756 100644
--- a/scripts/cache.py
+++ b/scripts/cache.py
@@ -22,6 +22,7 @@ Design notes:
     cache failure must never break a search.
 """
 
+import contextlib
 import hashlib
 import json
 import os
@@ -40,8 +41,15 @@ def _cache_path() -> Path:
     return DEFAULT_CACHE_DIR / "cache.db"
 
 
-def _connect(path: Path) -> sqlite3.Connection:
-    """Open a connection with WAL mode and ensure the schema exists."""
+def _connect(path: Path):
+    """Open a connection with WAL mode and ensure the schema exists.
+
+    Returns a :class:`contextlib.closing` wrapper so ``with _connect(...) as conn:``
+    closes the connection on exit. ``sqlite3.Connection.__exit__`` only commits /
+    rolls back the transaction — it does **not** call ``close()``, which leaks
+    file descriptors across many cache operations (especially under
+    ``--queries-file`` + ``--cache-ttl`` batch runs).
+    """
     path.parent.mkdir(parents=True, exist_ok=True)
     conn = sqlite3.connect(str(path), timeout=10)
     # WAL allows concurrent readers alongside a single writer, which matters
@@ -59,7 +67,7 @@ def _connect(path: Path) -> sqlite3.Connection:
         """
     )
     conn.commit()
-    return conn
+    return contextlib.closing(conn)
 
 
 def _make_key(params: dict) -> str:
diff --git a/scripts/common.py b/scripts/common.py
index e4ff6e8..8111646 100644
--- a/scripts/common.py
+++ b/scripts/common.py
@@ -60,8 +60,12 @@ def setup_logging(verbose: bool = False, quiet: bool = False) -> None:
 MAX_RETRIES = 3
 RETRY_BACKOFF_BASE = 1.5  # seconds; exponential backoff + jitter
 
-# HTTP status codes that are worth retrying (rate limit + gateway errors)
-RETRYABLE_STATUS = frozenset({429, 502, 503, 504})
+# HTTP status codes worth retrying. 403 is included so fetch_url's UA-fallback
+# loop can kick in when a site blocks the default searxng-cli User-Agent
+# (a fresh UA is tried on each retry attempt). search.py also retries 403 —
+# it doesn't switch UAs, so true auth failures waste ~3 attempts, accepted
+# as a trade-off for one shared retry policy across both scripts.
+RETRYABLE_STATUS = frozenset({403, 429, 502, 503, 504})
 
 # Browser-like UA strings for fallback when the searxng-cli UA is blocked
 FALLBACK_UAS = [
@@ -302,6 +306,29 @@ E_EMPTY = "E_EMPTY"
 E_INPUT = "E_INPUT"
 E_INTERNAL = "E_INTERNAL"
 
+# 每个 E_* 配套的可操作恢复建议，让 AI Agent 能自决策下一步动作，
+# 而不是盲目重试或放弃。在 _emit_error 的 JSON 输出中作为 recovery_hint 字段。
+RECOVERY_HINTS = {
+    E_CONFIG: "Provide -i/--instance, set SEARXNG_INSTANCE env var, or create "
+              "searxng.toml/instances.txt config file.",
+    E_AUTH: "Verify --auth-bearer/--auth-basic credentials or "
+            "SEARXNG_BEARER_TOKEN/SEARXNG_BASIC_AUTH env vars. Check token "
+            "expiry and instance access permissions.",
+    E_NETWORK: "Retry with backoff, or try a different SearXNG instance. "
+               "Check network connectivity, proxy settings, and instance uptime.",
+    E_RATE_LIMIT: "Wait before retrying (exponential backoff). Reduce query "
+                  "frequency, narrow --time-range, or distribute load across "
+                  "multiple instances.",
+    E_INPUT: "Check query syntax, --categories values, --time-range format, "
+             "and flag combinations. Use --help for valid options.",
+    E_PARSE: "The instance returned malformed data. Try a different instance, "
+             "switch --method, or check if the instance version is compatible.",
+    E_EMPTY: "Refine the query (more specific terms), broaden --time-range, "
+             "add --categories, or increase --pageno to find more results.",
+    E_INTERNAL: "This is likely a bug. Re-run with --verbose and report the "
+                "full output for diagnosis.",
+}
+
 
 def classify_error(exc: BaseException) -> str:
     """将异常分类为结构化错误码，供 AI Agent 程序化处理。
@@ -350,18 +377,36 @@ def classify_error(exc: BaseException) -> str:
     if isinstance(exc, (ValueError, _json.JSONDecodeError)):
         return E_PARSE
 
-    # RuntimeError：从消息中推断（search_multi 的 "All N instances failed" 等）
+    # RuntimeError：从消息中推断（search_multi 的 "All N instances failed.
+    # Last error: HTTP Error 403: Forbidden" 等）。并行路径现在会把 last_error
+    # 拼进消息，让这里能提取真实错误类型，而不是一律误判 E_NETWORK。
     msg = str(exc).lower()
     if isinstance(exc, RuntimeError):
+        # 先检查 auth/rate-limit 关键字（最常见，来自 last_error 详情）
         if "auth" in msg or "403" in msg or "401" in msg:
             return E_AUTH
         if "rate" in msg or "429" in msg:
             return E_RATE_LIMIT
+        # 从 "http error NNN" / "http NNN" 模式中提取状态码，
+        # 正确分类 "All instances failed. Last error: HTTP Error 403" 等
+        import re as _re
+        status_match = _re.search(r'http(?: error)? (\d{3})', msg)
+        if status_match:
+            status = int(status_match.group(1))
+            if status == 429:
+                return E_RATE_LIMIT
+            if status in (401, 403):
+                return E_AUTH
+            if 400 <= status < 500:
+                return E_INPUT
+            if 500 <= status < 600:
+                return E_NETWORK
+        # 所有实例失败的通用模式（无更具体的 HTTP 状态码时才判为网络错误）
         if "all" in msg and "instance" in msg and "fail" in msg:
             return E_NETWORK
         if "parse" in msg or "json" in msg or "html" in msg:
             return E_PARSE
-        if "not found" in msg or "no " in msg and "instance" in msg:
+        if "not found" in msg or ("no " in msg and "instance" in msg):
             return E_CONFIG
         return E_INTERNAL
 
diff --git a/scripts/fetch.py b/scripts/fetch.py
index fc00907..4de50ae 100644
--- a/scripts/fetch.py
+++ b/scripts/fetch.py
@@ -513,35 +513,42 @@ def fetch_url(url: str, timeout: int = 15, user_agent: str = None,
             if _HAS_REQUESTS:
                 resp = _requests.get(url, timeout=timeout, headers=headers,
                                      allow_redirects=allow_redirects, stream=True)
-                resp.raise_for_status()
+                # stream=True holds the socket open; must close explicitly,
+                # including on raise_for_status() / max_size break / decode
+                # errors — otherwise the connection leaks back to the pool
+                # and long-running agents exhaust ports.
+                try:
+                    resp.raise_for_status()
 
-                # Read: unlimited if max_size is None, chunked with limit otherwise
-                if max_size is None:
-                    raw = resp.content
-                    truncated = False
-                else:
-                    chunks = []
-                    total = 0
-                    for chunk in resp.iter_content(chunk_size=65536, decode_unicode=False):
-                        if chunk:
-                            chunks.append(chunk)
-                            total += len(chunk)
-                            if total > max_size:
-                                break
-                    raw = b"".join(chunks)
-                    truncated = total > max_size
+                    # Read: unlimited if max_size is None, chunked with limit otherwise
+                    if max_size is None:
+                        raw = resp.content
+                        truncated = False
+                    else:
+                        chunks = []
+                        total = 0
+                        for chunk in resp.iter_content(chunk_size=65536, decode_unicode=False):
+                            if chunk:
+                                chunks.append(chunk)
+                                total += len(chunk)
+                                if total > max_size:
+                                    break
+                        raw = b"".join(chunks)
+                        truncated = total > max_size
 
-                if encoding:
-                    content = raw.decode(encoding)
-                else:
-                    charset = detect_charset(raw, resp.headers.get("Content-Type", ""))
-                    try:
-                        content = raw.decode(charset)
-                    except (UnicodeDecodeError, LookupError):
-                        content = raw.decode("utf-8", errors="replace")
+                    if encoding:
+                        content = raw.decode(encoding)
+                    else:
+                        charset = detect_charset(raw, resp.headers.get("Content-Type", ""))
+                        try:
+                            content = raw.decode(charset)
+                        except (UnicodeDecodeError, LookupError):
+                            content = raw.decode("utf-8", errors="replace")
 
-                return FetchResult(content, resp.headers.get("Content-Type", ""),
-                                   resp.url, truncated, ua)
+                    return FetchResult(content, resp.headers.get("Content-Type", ""),
+                                       resp.url, truncated, ua)
+                finally:
+                    resp.close()
 
             # stdlib fallback
             req = urllib.request.Request(url, headers=headers)
@@ -588,7 +595,7 @@ def fetch_url(url: str, timeout: int = 15, user_agent: str = None,
                 logger.info(f"  Fetch retry {attempt+1}/{max_retries} ({e}) in {delay:.1f}s")
                 time.sleep(delay)
                 continue
-            raise RuntimeError(f"HTTP {e.code} for {url}")
+            raise RuntimeError(f"HTTP {e.code} for {url}") from e
         except (urllib.error.URLError, OSError, TimeoutError) as e:
             last_error = e
             if attempt < max_retries:
@@ -596,7 +603,7 @@ def fetch_url(url: str, timeout: int = 15, user_agent: str = None,
                 logger.info(f"  Fetch retry {attempt+1}/{max_retries} ({e}) in {delay:.1f}s")
                 time.sleep(delay)
                 continue
-            raise RuntimeError(f"Request failed for {url}: {e}")
+            raise RuntimeError(f"Request failed for {url}: {e}") from e
         except Exception as e:
             # requests backend: retry only on connection errors (no response)
             # or transient 429/5xx; do NOT retry permanent errors like 404.
@@ -608,9 +615,9 @@ def fetch_url(url: str, timeout: int = 15, user_agent: str = None,
                     logger.info(f"  Fetch retry {attempt+1}/{max_retries} ({e}) in {delay:.1f}s")
                     time.sleep(delay)
                     continue
-            raise RuntimeError(f"Request failed for {url}: {e}")
+            raise RuntimeError(f"Request failed for {url}: {e}") from e
 
-    raise RuntimeError(f"All {max_retries+1} attempts failed for {url}: {last_error}")
+    raise RuntimeError(f"All {max_retries+1} attempts failed for {url}: {last_error}") from last_error
 
 
 # ----- Main -----
diff --git a/scripts/search.py b/scripts/search.py
index 9dcf1d5..353827c 100644
--- a/scripts/search.py
+++ b/scripts/search.py
@@ -24,11 +24,12 @@ from pathlib import Path
 
 # Allow running standalone from any working directory
 sys.path.insert(0, str(Path(__file__).resolve().parent))
-from _config import USER_AGENT, VERSION
+from _config import SCHEMA_VERSION, USER_AGENT, VERSION
 from common import (
     RETRYABLE_STATUS,
     RETRY_BACKOFF_BASE,
     MAX_RETRIES,
+    RECOVERY_HINTS,
     apply_proxy,
     build_auth_headers,
     classify_error,
@@ -143,7 +144,7 @@ class SearXNGHTMLParser(HTMLParser):
                 self._in_time = True
                 self._text_buf = []
             elif tag in ("script", "style"):
-                self._skip_depth = 1
+                self._skip_depth += 1
 
         # Suggestions: <div id="suggestions"> or class containing "suggestion"
         if tag_id == "suggestions" or "suggestion" in classes:
@@ -312,6 +313,17 @@ def _read_instance_file(path: Path) -> list:
                 continue
             out.extend(parse_instances(line))
         return out
+    except RuntimeError as e:
+        # tomllib 缺失（Python 3.8-3.10 未装 tomli）是可恢复的——可改用
+        # instances.txt——但必须明确提示用户，而不是静默返回空列表让 main
+        # 报 "no instance resolved"，让用户困惑真正的失败原因。
+        msg = str(e).lower()
+        if "toml" in msg and ("3.11" in msg or "tomli" in msg):
+            logger.error(f"Cannot parse '{path}': {e} "
+                         f"(consider 'pip install tomli' or use instances.txt)")
+        else:
+            logger.warning(f"Warning: cannot read instance file '{path}': {e}")
+        return []
     except Exception as e:
         logger.warning(f"Warning: cannot read instance file '{path}': {e}")
         return []
@@ -423,7 +435,7 @@ def _retry_with_backoff(fn, max_retries: int = MAX_RETRIES, base_delay: float =
         try:
             return fn()
         except urllib.error.HTTPError as e:
-            if e.code in RETRYABLE_STATUS:  # 429 rate-limit + 5xx gateway errors
+            if e.code in RETRYABLE_STATUS:  # 403 (UA block) + 429 + 5xx
                 last_error = e
                 if attempt < max_retries:
                     delay = base_delay * (2 ** attempt) + random.uniform(0, 1)
@@ -524,14 +536,22 @@ def search_multi(instance_urls: list, params: dict, method: str = "GET",
         last_error = None
         for instance in instance_urls:
             logger.info(f"Trying {instance}...")
+            emit_progress("instance_try", url=instance, attempt=1)
+            start = time.time()
             try:
                 def _do():
                     return search_single(instance, params, method=method,
                                          timeout=timeout, auth_headers=auth_headers)
-                return _retry_with_backoff(_do, max_retries=retry_per)
+                result = _retry_with_backoff(_do, max_retries=retry_per)
+                emit_progress("instance_ok", url=instance,
+                              latency=round(time.time() - start, 3),
+                              results=len(result.get("results", [])) if result else 0)
+                return result
             except Exception as e:
                 last_error = e
                 logger.info(f"  Failed: {e}")
+                emit_progress("instance_fail", url=instance,
+                              error=str(e), error_code=classify_error(e))
                 continue
         raise RuntimeError(f"All {len(instance_urls)} instances failed. Last error: {last_error}")
 
@@ -540,15 +560,24 @@ def search_multi(instance_urls: list, params: dict, method: str = "GET",
     logger.info(f"Trying {len(instance_urls)} instances in parallel...")
 
     def _task(instance: str):
+        emit_progress("instance_try", url=instance, attempt=1)
+        start = time.time()
         def _do():
             return search_single(instance, params, method=method,
                                  timeout=timeout, auth_headers=auth_headers)
         try:
-            return instance, _retry_with_backoff(_do, max_retries=retry_per)
+            result = _retry_with_backoff(_do, max_retries=retry_per)
+            emit_progress("instance_ok", url=instance,
+                          latency=round(time.time() - start, 3),
+                          results=len(result.get("results", [])) if result else 0)
+            return instance, result
         except Exception as e:
+            emit_progress("instance_fail", url=instance,
+                          error=str(e), error_code=classify_error(e))
             return instance, e
 
     results_by_url = {}
+    last_parallel_error = None
     with ThreadPoolExecutor(max_workers=min(len(instance_urls), 8)) as ex:
         futures = {ex.submit(_task, u): u for u in instance_urls}
         for fut in as_completed(futures):
@@ -558,6 +587,10 @@ def search_multi(instance_urls: list, params: dict, method: str = "GET",
             except Exception:
                 continue
             if isinstance(res, Exception):
+                # 保留最后一个失败详情，让 classify_error 能从消息中提取
+                # 真实错误类型（401/403→E_AUTH，429→E_RATE_LIMIT 等），
+                # 而不是一律误判为 E_NETWORK。
+                last_parallel_error = res
                 logger.info(f"  Failed {u}: {res}")
             else:
                 results_by_url[u] = res
@@ -567,7 +600,8 @@ def search_multi(instance_urls: list, params: dict, method: str = "GET",
         if u in results_by_url:
             return results_by_url[u]
 
-    raise RuntimeError(f"All {len(instance_urls)} instances failed (parallel).")
+    raise RuntimeError(f"All {len(instance_urls)} instances failed (parallel). "
+                       f"Last error: {last_parallel_error}")
 
 
 # ----- Output formatting -----
@@ -675,7 +709,10 @@ def verify_instances(instance_urls: list, timeout: int = 15,
             # users know whether their token is wrong or the instance is down.
             auth_status = ("rejected" if has_auth and e.code in (401, 403)
                            else ("ok" if has_auth else "n/a"))
-            return {"url": u, "reachable": e.code not in (401, 403, 404),
+            # 5xx 是服务器错误，实例虽然响应了但不可用，应视为不可达。
+            # 400 可能只是请求格式问题，实例本身在线，仍算可达。
+            is_5xx = 500 <= e.code < 600
+            return {"url": u, "reachable": e.code not in (401, 403, 404) and not is_5xx,
                     "json_supported": False, "post_supported": None,
                     "config_endpoint": None, "engines": [],
                     "latency": round(time.time() - start, 3),
@@ -900,7 +937,9 @@ def deduplicate_results(results: dict) -> dict:
     if not results.get("results"):
         return results
 
-    TRACKING_PREFIXES = ("utm_", "gclid", "fbclid", "mc_", "ref", "ref_")
+    # 跟踪参数前缀。裸 "ref" 过于宽泛（会误删 reference/refcode 等正常参数），
+    # 收紧为 "ref_" 只匹配 ref_source/ref_campaign 等跟踪参数。
+    TRACKING_PREFIXES = ("utm_", "gclid", "fbclid", "mc_", "ref_")
 
     def _normalize_url(url: str) -> str:
         try:
@@ -1052,6 +1091,7 @@ def _format_results(results: dict, args) -> str:
     the exact same formatting for each per-query block.
     """
     if args.format == "json":
+        results["schema_version"] = SCHEMA_VERSION
         return json.dumps(results, indent=2, ensure_ascii=False)
     if args.format == "urls":
         return format_urls(results)
@@ -1188,9 +1228,89 @@ def _run_single_query(query: str, args, instance_urls: list,
 
     result_count = len(results.get("results", []))
     emit_progress("done", results=result_count, query=query)
+    # 清理内部 _fallback 字段，避免泄漏到 JSON 输出。
+    # fetched_source（对 AI 有用的公开字段）已在 --fetch 路径中设置。
+    results.pop("_fallback", None)
     return results, None, None
 
 
+def _get_output_schema():
+    """Return the JSON Schema describing --format json output.
+
+    Used by ``--dump-schema`` so AI agents can programmatically discover the
+    output structure without parsing prose documentation.
+    """
+    return {
+        "$schema": "https://json-schema.org/draft/2020-12/schema",
+        "title": "SearXNG CLI Search Result",
+        "schema_version": SCHEMA_VERSION,
+        "description": "Output schema for 'python search.py --format json' (single query). "
+                       "Batch mode (--queries-file) wraps results in "
+                       '{"schema_version, queries:[]}.',
+        "type": "object",
+        "properties": {
+            "schema_version": {
+                "type": "string",
+                "const": SCHEMA_VERSION,
+                "description": "Output schema version. Bump on breaking field changes.",
+            },
+            "query": {"type": "string", "description": "The search query string."},
+            "number_of_results": {
+                "type": "integer",
+                "description": "Total matches reported by SearXNG (JSON path) or "
+                               "count of parsed results (HTML fallback path).",
+            },
+            "results": {
+                "type": "array",
+                "description": "Search result items, ordered by relevance (score desc).",
+                "items": {
+                    "type": "object",
+                    "properties": {
+                        "title": {"type": "string"},
+                        "url": {"type": "string", "format": "uri"},
+                        "engine": {"type": "string", "description": "Source engine name."},
+                        "score": {"type": ["number", "null"]},
+                        "published_date": {"type": ["string", "null"]},
+                        "content": {"type": "string", "description": "Snippet/summary text."},
+                    },
+                    "required": ["title", "url"],
+                },
+            },
+            "unresponsive_engines": {
+                "type": "array",
+                "items": {"type": "string"},
+                "description": "Engines that failed to respond.",
+            },
+            "suggestions": {
+                "type": "array",
+                "items": {"type": "string"},
+                "description": "Related query suggestions from the instance.",
+            },
+            "fetched": {
+                "type": "array",
+                "description": "Present only when --fetch N is used. Page content "
+                               "for the top N results.",
+                "items": {
+                    "type": "object",
+                    "properties": {
+                        "url": {"type": "string"},
+                        "text": {"type": "string"},
+                        "text_length": {"type": "integer"},
+                        "error": {"type": "string"},
+                    },
+                },
+            },
+            "fetched_source": {
+                "type": "string",
+                "enum": ["json", "html"],
+                "description": "Present only when --fetch is used. Indicates whether "
+                               "search results came from JSON API or HTML fallback.",
+            },
+        },
+        "required": ["query", "results"],
+    }
+
+
 def _emit_error(message: str, args, query: str = None, exit_code: int = 1,
                 error_code: str = None):
     """Emit an error and exit.
@@ -1201,22 +1321,30 @@ def _emit_error(message: str, args, query: str = None, exit_code: int = 1,
 
     The JSON shape is::
 
-        {"error": "...", "exit_code": N, "error_code": "E_*", "query": "..."}
+        {"error": "...", "exit_code": N, "error_code": "E_*",
+         "recovery_hint": "...", "query": "..."}
 
     ``error_code`` 是结构化错误码（E_CONFIG/E_AUTH/E_NETWORK 等），让 AI
-    Agent 程序化判断错误类型并采取恢复策略。``query`` 仅在提供时包含。
+    Agent 程序化判断错误类型并采取恢复策略。``recovery_hint`` 给出可操作的
+    恢复建议，让 AI 能自决策下一步动作。``query`` 仅在提供时包含。
     """
     if getattr(args, "format", None) == "json":
         payload = {"error": message, "exit_code": exit_code}
         if error_code:
             payload["error_code"] = error_code
+            hint = RECOVERY_HINTS.get(error_code)
+            if hint:
+                payload["recovery_hint"] = hint
         if query:
             payload["query"] = query
         print(json.dumps(payload, indent=2, ensure_ascii=False))
     else:
         prefix = f"[query: {query}] " if query else ""
         code_prefix = f"[{error_code}] " if error_code else ""
-        logger.error(f"{prefix}{code_prefix}Error: {message}")
+        hint_suffix = ""
+        if error_code and error_code in RECOVERY_HINTS:
+            hint_suffix = f"\n  Hint: {RECOVERY_HINTS[error_code]}"
+        logger.error(f"{prefix}{code_prefix}Error: {message}{hint_suffix}")
     sys.exit(exit_code)
 
 
@@ -1406,13 +1534,35 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
                         help="Delete all cached entries and exit (no search performed)")
     parser.add_argument("--cache-stats", action="store_true",
                         help="Print cache statistics (entry count, age, size, path) and exit")
+    parser.add_argument("--dump-schema", action="store_true",
+                        help="Print the JSON Schema for --format json output and exit. "
+                             "Lets AI agents programmatically discover field names and types.")
     parser.add_argument("--version", action="version", version=f"searxng-cli v{VERSION}")
 
     args = parser.parse_args()
 
+    # --dump-schema：输出 JSON Schema 到 stdout 并退出，AI Agent 可程序化发现字段
+    if getattr(args, "dump_schema", False):
+        print(json.dumps(_get_output_schema(), indent=2, ensure_ascii=False))
+        sys.exit(0)
+
     # 启用 --progress 进度事件（JSON Lines 到 stderr）
     set_progress_enabled(getattr(args, "progress", False))
 
+    # --stream 只在单查询 + --format json 下有效。batch 模式输出 JSON 数组，
+    # 非 json 格式无 JSON Lines 语义；两种组合都显式报错 E_INPUT，避免静默失效
+    # 让 AI Agent 误以为流式输出已生效。
+    if getattr(args, "stream", False):
+        if args.queries_file:
+            _emit_error("--stream cannot be used with --queries-file: batch mode "
+                        "emits a JSON array, not JSON Lines. Drop --stream for "
+                        "batch output, or use a single --query with --stream.",
+                        args, error_code=E_INPUT)
+        if args.format != "json":
+            _emit_error(f"--stream requires --format json (current: {args.format}). "
+                        "JSON Lines streaming only produces valid output with json format.",
+                        args, error_code=E_INPUT)
+
     # --query is required unless we're doing a non-search operation.
     # --queries-file is an alternative to --query for batch mode.
     if (not args.verify and not args.query and not args.queries_file
@@ -1427,6 +1577,33 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
         apply_proxy(args.proxy)
         logger.info(f"Proxy: {args.proxy}")
 
+    # --clear-cache / --cache-stats 不需要实例，在实例解析之前处理并退出。
+    # 避免无 -i 时报 E_CONFIG "no instance resolved" 让 AI 困惑。
+    if args.clear_cache:
+        removed = cache_module.clear()
+        logger.info(f"Cleared {removed} cache entr{'y' if removed == 1 else 'ies'}.")
+        sys.exit(0)
+
+    if args.cache_stats:
+        s = cache_module.stats()
+        if args.format == "json":
+            # JSON 模式：结构化数据走 stdout，AI Agent 可管道解析
+            print(json.dumps(s, indent=2, ensure_ascii=False))
+        else:
+            # 非 JSON 模式：人类可读的状态信息走 stderr，保持 stdout 纯净，
+            # 避免 AI Agent 用 --format json 解析 stdout 时被非 JSON 污染。
+            print(f"Cache path:  {s.get('path', '?')}", file=sys.stderr)
+            print(f"Entries:     {s.get('entries', 0)}", file=sys.stderr)
+            size = s.get("size_bytes", 0)
+            print(f"Size:        {size:,} bytes ({size / 1024:.1f} KB)", file=sys.stderr)
+            if s.get("oldest_created_at"):
+                print(f"Oldest:      {time.ctime(s['oldest_created_at'])}", file=sys.stderr)
+            if s.get("newest_created_at"):
+                print(f"Newest:      {time.ctime(s['newest_created_at'])}", file=sys.stderr)
+            if s.get("error"):
+                print(f"Error:       {s['error']}", file=sys.stderr)
+        sys.exit(0)
+
     # Resolve instance(s): -i > SEARXNG_INSTANCE env > config file
     instance_urls = resolve_instances(args.instance)
     # Fallback: if --config was used, instance may be in the config dict
@@ -1441,9 +1618,26 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
             instance_urls = [u if u.startswith(("http://", "https://"))
                              else "https://" + u for u in raw if u and str(u).strip()]
     if not instance_urls:
+        # Python 3.8-3.10 无 tomllib 时，.toml 配置文件无法读取。检查这种
+        # 情况并在错误信息中附加提示，让 AI Agent 能给出可操作的恢复建议。
+        toml_hint = ""
+        try:
+            import tomllib  # Python 3.11+
+        except ModuleNotFoundError:
+            try:
+                import tomli  # type: ignore[import-not-found]
+            except ModuleNotFoundError:
+                toml_candidates = [
+                    Path.cwd() / "searxng.toml",
+                    Path.home() / ".config" / "searxng-cli" / "searxng.toml",
+                ]
+                if any(p.exists() for p in toml_candidates):
+                    toml_hint = (" (hint: a searxng.toml file exists but cannot be "
+                                 "read on Python < 3.11 without the 'tomli' package. "
+                                 "Run 'pip install tomli' or use instances.txt instead.)")
         _emit_error("no SearXNG instance resolved. Provide -i/--instance, set the "
                     "SEARXNG_INSTANCE environment variable, or create a searxng.toml / "
-                    "instances.txt config file.", args, error_code=E_CONFIG)
+                    "instances.txt config file." + toml_hint, args, error_code=E_CONFIG)
 
     # Build auth headers if provided (needed by both verify and search).
     # Credentials may come from CLI flag, file, config file, or env var
@@ -1473,29 +1667,6 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
         _print_verify_report(report, as_json=(args.format == "json"))
         sys.exit(0)
 
-    # Cache management modes (no search performed)
-    if args.clear_cache:
-        removed = cache_module.clear()
-        logger.info(f"Cleared {removed} cache entr{'y' if removed == 1 else 'ies'}.")
-        sys.exit(0)
-
-    if args.cache_stats:
-        s = cache_module.stats()
-        if args.format == "json":
-            print(json.dumps(s, indent=2, ensure_ascii=False))
-        else:
-            print(f"Cache path:  {s.get('path', '?')}")
-            print(f"Entries:     {s.get('entries', 0)}")
-            size = s.get("size_bytes", 0)
-            print(f"Size:        {size:,} bytes ({size / 1024:.1f} KB)")
-            if s.get("oldest_created_at"):
-                print(f"Oldest:      {time.ctime(s['oldest_created_at'])}")
-            if s.get("newest_created_at"):
-                print(f"Newest:      {time.ctime(s['newest_created_at'])}")
-            if s.get("error"):
-                print(f"Error:       {s['error']}")
-        sys.exit(0)
-
     if args.fail_fast:
         instance_urls = instance_urls[:1]
 
@@ -1519,23 +1690,27 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
 
         logger.info(f"Running {len(queries)} queries from {args.queries_file}...")
         batch = []
-        any_ok = False
+        any_with_results = False
+        error_count = 0
         for i, q in enumerate(queries, 1):
             logger.info(f"\n[{i}/{len(queries)}] {q}")
             results, err, err_code = _run_single_query(q, args, instance_urls,
                                                         auth_headers, ttl_seconds)
             if err:
+                error_count += 1
                 logger.error(f"  [ERROR] {err}")
-                entry = {"query": q, "error": err}
+                entry = {"query": q, "status": "error", "error": err}
                 if err_code:
                     entry["error_code"] = err_code
                 batch.append(entry)
             else:
-                any_ok = True
-                batch.append({"query": q, "results": results})
+                if len(results.get("results", [])) > 0:
+                    any_with_results = True
+                batch.append({"query": q, "status": "ok", "results": results})
 
         if args.format == "json":
-            output = json.dumps(batch, indent=2, ensure_ascii=False)
+            output = json.dumps({"schema_version": SCHEMA_VERSION, "queries": batch},
+                                indent=2, ensure_ascii=False)
         elif args.format == "csv":
             import csv as csv_mod
             import io
@@ -1588,27 +1763,49 @@ Use --config FILE to load a non-default config file (overrides the auto-discover
             logger.info(f"Saved results to {args.output}")
         else:
             print(output)
-        # Exit 0 if at least one query succeeded; 1 only if all failed.
-        sys.exit(0 if any_ok else 1)
+        # Exit code semantics — aligned with single-query mode so AI agents
+        # can use one consistent rule:
+        #   1 = all queries errored (fatal)
+        #   2 = no query returned any results (empty), though at least one
+        #       searched successfully without error
+        #   0 = at least one query returned results
+        if error_count == len(queries):
+            sys.exit(1)
+        if not any_with_results:
+            sys.exit(2)
+        sys.exit(0)
 
     # ----- Single query mode -----
     results, err, err_code = _run_single_query(args.query, args, instance_urls,
                                                 auth_headers, ttl_seconds)
-    if err:
-        _emit_error(err, args, query=args.query, error_code=err_code)
 
-    # --stream: JSON Lines 流式输出，每条结果一行，AI 可增量处理
+    # --stream: JSON Lines 流式输出，每条结果一行，AI 可增量处理。
+    # stream 模式下所有输出（包括错误）都是单行 JSON，保持 JSON Lines 格式一致性。
+    # 非 stream 模式的错误走 _emit_error（多行 JSON 或 stderr 文本）。
     if getattr(args, "stream", False) and args.format == "json":
+        if err:
+            error_event = {"type": "error", "error": err, "query": args.query}
+            if err_code:
+                error_event["error_code"] = err_code
+                hint = RECOVERY_HINTS.get(err_code)
+                if hint:
+                    error_event["recovery_hint"] = hint
+            print(json.dumps(error_event, ensure_ascii=False), flush=True)
+            sys.exit(1)
         for r in results.get("results", []):
             print(json.dumps({"type": "result", "result": r},
                              ensure_ascii=False), flush=True)
         print(json.dumps({"type": "done",
+                          "schema_version": SCHEMA_VERSION,
                           "count": len(results.get("results", [])),
                           "query": args.query}, ensure_ascii=False), flush=True)
         if not results.get("results"):
             sys.exit(2)
         sys.exit(0)
 
+    if err:
+        _emit_error(err, args, query=args.query, error_code=err_code)
+
     output = _format_results(results, args)
     if args.output:
         with open(args.output, "w", encoding="utf-8") as f:
diff --git a/tests/test_batch.py b/tests/test_batch.py
new file mode 100644
index 0000000..df19c9f
--- /dev/null
+++ b/tests/test_batch.py
@@ -0,0 +1,134 @@
+"""Tests for --queries-file batch mode: exit code semantics and JSON schema.
+
+Covers:
+  * Exit codes: all-empty (no error) -> 2, all-error -> 1, partial -> 0
+  * Batch JSON shape: {"schema_version": "1.0", "queries": [...]}
+  * Per-entry "status" field ("ok"/"error") and result/error payload shape
+
+Uses in-process main() with search_multi mocked so no network is touched.
+``--retry 0`` is passed to avoid backoff sleeps when search_multi raises.
+"""
+import json
+import sys
+import urllib.error
+from unittest.mock import patch
+
+import pytest
+
+import search as search_mod
+from search import main
+
+
+def _batch_argv(queries_file_path, fmt="json"):
+    """Build the sys.argv for a batch main() invocation.
+
+    ``--retry 0`` keeps failing tests fast (no backoff sleeps).
+    """
+    return ["search.py", "-i", "https://x.example.com",
+            "--queries-file", str(queries_file_path),
+            "--format", fmt, "--retry", "0"]
+
+
+# ===== batch exit code semantics =====
+
+def test_batch_all_empty_results_exits_2(tmp_path, capsys):
+    """All queries return empty results (no error) -> exit 2."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\nq2\n", encoding="utf-8")
+    empty = {"results": []}
+    with patch.object(search_mod, "search_multi", return_value=empty):
+        with pytest.raises(SystemExit) as exc_info:
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    assert exc_info.value.code == 2
+
+
+def test_batch_all_error_exits_1(tmp_path, capsys):
+    """All queries error -> exit 1."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\nq2\n", encoding="utf-8")
+    err = urllib.error.URLError("connection refused")
+    with patch.object(search_mod, "search_multi", side_effect=err):
+        with pytest.raises(SystemExit) as exc_info:
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    assert exc_info.value.code == 1
+
+
+def test_batch_partial_results_exits_0(tmp_path, capsys):
+    """At least one query returns results -> exit 0."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\nq2\n", encoding="utf-8")
+    with_data = {"results": [{"url": "https://a.com/1", "title": "A"}]}
+    empty = {"results": []}
+    with patch.object(search_mod, "search_multi",
+                      side_effect=[with_data, empty]):
+        with pytest.raises(SystemExit) as exc_info:
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    assert exc_info.value.code == 0
+
+
+# ===== batch unified JSON schema =====
+
+def test_batch_json_has_schema_version_and_queries(tmp_path, capsys):
+    """Batch JSON output wraps entries in {schema_version, queries}."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\n", encoding="utf-8")
+    mock_results = {"results": [{"url": "https://a.com/1", "title": "A"}]}
+    with patch.object(search_mod, "search_multi", return_value=mock_results):
+        with pytest.raises(SystemExit):
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    assert data["schema_version"] == "1.0"
+    assert "queries" in data
+    assert isinstance(data["queries"], list)
+    assert len(data["queries"]) == 1
+
+
+def test_batch_entry_has_status_field(tmp_path, capsys):
+    """Each batch entry has a 'status' field of 'ok' or 'error'."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\nq2\n", encoding="utf-8")
+    ok_results = {"results": [{"url": "https://a.com/1", "title": "A"}]}
+    err = urllib.error.URLError("down")
+    with patch.object(search_mod, "search_multi",
+                      side_effect=[ok_results, err]):
+        with pytest.raises(SystemExit):
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    statuses = [e["status"] for e in data["queries"]]
+    assert "ok" in statuses
+    assert "error" in statuses
+
+
+def test_batch_success_entry_has_results_error_entry_has_error_and_code(tmp_path, capsys):
+    """ok entry has 'results'; error entry has 'error' and 'error_code'."""
+    qf = tmp_path / "queries.txt"
+    qf.write_text("q1\nq2\n", encoding="utf-8")
+    ok_results = {"results": [{"url": "https://a.com/1", "title": "A"}]}
+    err = urllib.error.URLError("connection refused")
+    with patch.object(search_mod, "search_multi",
+                      side_effect=[ok_results, err]):
+        with pytest.raises(SystemExit):
+            with patch.object(sys, "argv", _batch_argv(qf)):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    ok_entry = next(e for e in data["queries"] if e["status"] == "ok")
+    assert "results" in ok_entry
+    err_entry = next(e for e in data["queries"] if e["status"] == "error")
+    assert "error" in err_entry
+    assert "error_code" in err_entry
+    # URLError -> E_NETWORK per classify_error
+    assert err_entry["error_code"] == "E_NETWORK"
diff --git a/tests/test_cli_e2e.py b/tests/test_cli_e2e.py
index 89b64ff..ec6c9cd 100644
--- a/tests/test_cli_e2e.py
+++ b/tests/test_cli_e2e.py
@@ -23,7 +23,7 @@ from types import SimpleNamespace
 
 import pytest
 
-from search import _run_single_query, _emit_error, _build_params
+from search import _run_single_query, _emit_error, _build_params, _format_results
 import cache as cache_module
 
 PROJECT_ROOT = Path(__file__).resolve().parent.parent
@@ -256,7 +256,7 @@ def test_cli_version_prints_version():
     """`--version` exits 0 and prints the version string."""
     r = _run_cli("--version")
     assert r.returncode == 0
-    assert "1.7.0" in r.stdout
+    assert "1.8.0" in r.stdout
     assert "searxng-cli" in r.stdout
 
 
@@ -294,3 +294,117 @@ def test_cli_cache_stats_outputs_json(tmp_path):
     data = json.loads(r.stdout)
     assert "entries" in data
     assert "path" in data
+
+
+# ===== --dump-schema (v1.8.0) =====
+
+def test_cli_dump_schema_outputs_valid_json():
+    """`--dump-schema` prints valid JSON with schema_version/title/properties.
+
+    The schema dump is a non-search operation: it exits 0 and does NOT
+    require --query or -i (it short-circuits before instance resolution).
+    """
+    r = _run_cli("--dump-schema")
+    assert r.returncode == 0
+    data = json.loads(r.stdout)
+    assert data["schema_version"] == "1.0"
+    assert data["title"] == "SearXNG CLI Search Result"
+    assert "properties" in data
+    assert isinstance(data["properties"], dict)
+
+
+def test_cli_dump_schema_does_not_require_query():
+    """`--dump-schema` exits 0 without --query (non-search operation)."""
+    r = _run_cli("--dump-schema")
+    assert r.returncode == 0
+    # The --query-required check must not fire for --dump-schema.
+    assert "required" not in r.stderr.lower()
+
+
+# ===== --stream mutual exclusion (v1.8.0) =====
+
+def test_cli_stream_with_queries_file_rejected(tmp_path):
+    """--stream + --queries-file is rejected with E_INPUT on stdout.
+
+    Batch mode emits a JSON array, not JSON Lines; the combination is
+    explicitly rejected so AI agents don't silently get the wrong format.
+    """
+    qf = tmp_path / "queries.txt"
+    qf.write_text("query\n", encoding="utf-8")
+    r = _run_cli("--stream", "--queries-file", str(qf),
+                 "--format", "json", "-i", "https://x.example.com")
+    assert r.returncode == 1
+    data = json.loads(r.stdout)
+    assert data["error_code"] == "E_INPUT"
+
+
+def test_cli_stream_with_csv_format_rejected():
+    """--stream + --format csv is rejected with E_INPUT.
+
+    csv is a non-json format, so _emit_error routes the error to stderr
+    (as a ``[E_INPUT]`` prefixed log line) rather than stdout JSON.
+    """
+    r = _run_cli("--stream", "--format", "csv", "-q", "test",
+                 "-i", "https://x.example.com")
+    assert r.returncode == 1
+    assert "E_INPUT" in r.stderr
+
+
+# ===== schema_version in single-query JSON (v1.8.0) =====
+
+def test_format_results_json_includes_schema_version():
+    """Single-query JSON output includes schema_version: '1.0'."""
+    results = {"results": [{"title": "T", "url": "https://example.com"}]}
+    args = SimpleNamespace(format="json")
+    out = _format_results(results, args)
+    parsed = json.loads(out)
+    assert parsed["schema_version"] == "1.0"
+
+
+# ===== _fallback field must not leak to JSON output (v1.8.0) =====
+
+def test_run_single_query_html_fallback_pops_underscore_fallback(monkeypatch):
+    """HTML-fallback's internal _fallback field is removed before output.
+
+    _run_single_query pops _fallback at the end so it never appears in
+    the JSON payload; fetched_source (the public field) is set separately
+    on the --fetch path.
+    """
+    args = _make_args(format="json")
+    fake = {"results": [{"url": "https://a.com/1", "title": "A"}],
+            "_fallback": "html"}
+    monkeypatch.setattr("search.search_multi", lambda *a, **kw: fake)
+
+    results, err, _ = _run_single_query("test", args,
+                                        ["https://x.example.com"], {}, 0)
+    assert err is None
+    # _fallback must be popped so it doesn't leak into JSON output
+    assert "_fallback" not in results
+    # And the serialized JSON also omits it
+    out = _format_results(results, args)
+    parsed = json.loads(out)
+    assert "_fallback" not in parsed
+
+
+def test_run_single_query_fetch_sets_fetched_source_from_html_fallback(monkeypatch):
+    """--fetch path sets fetched_source from _fallback (or 'json').
+
+    When the search came via HTML fallback (_fallback='html'), the
+    fetched_source field reflects that origin, while _fallback itself is
+    cleaned up and never reaches JSON output.
+    """
+    args = _make_args(fetch=1)
+    fake = {"results": [{"url": "https://a.com/1"}], "_fallback": "html"}
+    monkeypatch.setattr("search.search_multi", lambda *a, **kw: fake)
+    monkeypatch.setattr("search.fetch_top_results", lambda *a, **kw: [
+        {"url": "https://a.com/1", "status": "ok", "text": "page A",
+         "text_length": 6, "truncated": False},
+    ])
+
+    results, err, _ = _run_single_query("test", args,
+                                        ["https://x.example.com"], {}, 0)
+    assert err is None
+    # fetched_source reflects the HTML fallback origin
+    assert results["fetched_source"] == "html"
+    # _fallback still cleaned up
+    assert "_fallback" not in results
diff --git a/tests/test_common.py b/tests/test_common.py
index d429cd0..c8f0d67 100644
--- a/tests/test_common.py
+++ b/tests/test_common.py
@@ -143,8 +143,10 @@ def test_non_retryable_404():
     assert is_retryable_error(_http_error(404)) is False
 
 
-def test_non_retryable_403():
-    assert is_retryable_error(_http_error(403)) is False
+def test_retryable_403():
+    # 403 是可重试的：让 fetch_url 的 UA-fallback 循环有机会切换到浏览器 UA。
+    # 真正的认证错误会在重试耗尽后由 classify_error 归为 E_AUTH。
+    assert is_retryable_error(_http_error(403)) is True
 
 
 def test_non_retryable_200():
@@ -160,7 +162,8 @@ def test_retryable_os_error():
 
 
 def test_retryable_status_set_contents():
-    assert RETRYABLE_STATUS == frozenset({429, 502, 503, 504})
+    # 403 加入可重试集合，让 UA-fallback 在 UA 被屏蔽时有机会切换浏览器 UA
+    assert RETRYABLE_STATUS == frozenset({403, 429, 502, 503, 504})
 
 
 # ----- apply_proxy -----
diff --git a/tests/test_error_codes.py b/tests/test_error_codes.py
index 60e907d..7f567ee 100644
--- a/tests/test_error_codes.py
+++ b/tests/test_error_codes.py
@@ -231,3 +231,70 @@ def test_run_single_query_propagates_rate_limit():
         _, _, err_code = _run_single_query(
             "test", args, ["https://x.example.com"], {}, 0)
     assert err_code == E_RATE_LIMIT
+
+
+# ----- classify_error: HTTP status extraction from RuntimeError messages -----
+#
+# search_multi wraps the last error into its RuntimeError message, e.g.
+#   "All 3 instances failed. Last error: HTTP Error 403: Forbidden"
+# classify_error must extract the status code from that message rather than
+# always falling back to E_NETWORK.
+
+def test_classify_runtime_all_instances_failed_with_http_403_is_auth():
+    """'...Last error: HTTP Error 403' -> E_AUTH (not E_NETWORK)."""
+    err = RuntimeError("All 3 instances failed. Last error: HTTP Error 403: Forbidden")
+    assert classify_error(err) == E_AUTH
+
+
+def test_classify_runtime_all_instances_failed_with_http_500_is_network():
+    """'...Last error: HTTP Error 500' -> E_NETWORK (5xx server error)."""
+    err = RuntimeError("All 3 instances failed. Last error: HTTP Error 500: Internal Server Error")
+    assert classify_error(err) == E_NETWORK
+
+
+def test_classify_runtime_parallel_failed_with_http_429_is_rate_limit():
+    """'...(parallel). Last error: HTTP Error 429' -> E_RATE_LIMIT."""
+    err = RuntimeError("All 3 instances failed (parallel). Last error: HTTP Error 429: Too Many Requests")
+    assert classify_error(err) == E_RATE_LIMIT
+
+
+# ----- _emit_error: recovery_hint in JSON output -----
+#
+# recovery_hint gives AI agents an actionable suggestion per error_code.
+# Only present when error_code is known; omitted otherwise (backwards compat).
+
+def test_emit_error_json_includes_recovery_hint_for_config(capsys):
+    """JSON error with E_CONFIG includes the config recovery_hint."""
+    args = SimpleNamespace(format="json")
+    with pytest.raises(SystemExit):
+        _emit_error("no instance resolved", args, error_code=E_CONFIG)
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    assert data["error_code"] == E_CONFIG
+    assert "recovery_hint" in data
+    hint = data["recovery_hint"].lower()
+    assert "instance" in hint or "config" in hint
+
+
+def test_emit_error_json_includes_recovery_hint_for_auth(capsys):
+    """JSON error with E_AUTH includes the auth recovery_hint."""
+    args = SimpleNamespace(format="json")
+    with pytest.raises(SystemExit):
+        _emit_error("forbidden", args, error_code=E_AUTH)
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    assert data["error_code"] == E_AUTH
+    assert "recovery_hint" in data
+    hint = data["recovery_hint"].lower()
+    assert "credential" in hint or "token" in hint
+
+
+def test_emit_error_json_no_recovery_hint_without_error_code(capsys):
+    """No error_code -> no recovery_hint field (backwards compat)."""
+    args = SimpleNamespace(format="json")
+    with pytest.raises(SystemExit):
+        _emit_error("something broke", args)
+    out, _ = capsys.readouterr()
+    data = json.loads(out)
+    assert "error_code" not in data
+    assert "recovery_hint" not in data
diff --git a/tests/test_stream_progress.py b/tests/test_stream_progress.py
index 5975690..2623785 100644
--- a/tests/test_stream_progress.py
+++ b/tests/test_stream_progress.py
@@ -6,8 +6,9 @@ disabled by default, stream only works with --format json.
 """
 import json
 import sys
+import urllib.error
 from types import SimpleNamespace
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 import pytest
 
 import common
@@ -205,3 +206,115 @@ def test_stream_result_event_shape():
     assert parsed[0]["result"]["url"] == "https://x.com"
     assert parsed[-1]["type"] == "done"
     assert parsed[-1]["count"] == 1
+
+
+# ----- stream done/error: schema_version & recovery_hint (v1.8.0) -----
+
+def test_stream_done_includes_schema_version(capsys):
+    """stream done event includes the schema_version field."""
+    mock_results = {"results": [{"title": "t", "url": "https://x.com"}]}
+    with patch.object(search_mod, "search_multi", return_value=mock_results):
+        with pytest.raises(SystemExit) as exc_info:
+            with patch.object(sys, "argv", ["search.py", "-q", "test",
+                                            "-i", "https://x.example.com",
+                                            "--stream", "--format", "json",
+                                            "--retry", "0"]):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    assert exc_info.value.code == 0
+    out, _ = capsys.readouterr()
+    lines = [json.loads(l) for l in out.strip().split("\n") if l]
+    done_events = [e for e in lines if e["type"] == "done"]
+    assert len(done_events) == 1
+    assert done_events[0]["schema_version"] == "1.0"
+
+
+def test_stream_error_includes_recovery_hint(capsys):
+    """stream error event includes recovery_hint for classified errors.
+
+    HTTP 403 -> E_AUTH, which has a recovery_hint in RECOVERY_HINTS.
+    --retry 0 avoids backoff sleeps on the (mocked) 403.
+    """
+    err = urllib.error.HTTPError("url", 403, "Forbidden", {}, None)
+    with patch.object(search_mod, "search_multi", side_effect=err):
+        with pytest.raises(SystemExit) as exc_info:
+            with patch.object(sys, "argv", ["search.py", "-q", "test",
+                                            "-i", "https://x.example.com",
+                                            "--stream", "--format", "json",
+                                            "--retry", "0"]):
+                with patch.object(search_mod, "setup_logging"):
+                    main()
+    assert exc_info.value.code == 1
+    out, _ = capsys.readouterr()
+    lines = [json.loads(l) for l in out.strip().split("\n") if l]
+    error_events = [e for e in lines if e["type"] == "error"]
+    assert len(error_events) == 1
+    assert error_events[0]["error_code"] == "E_AUTH"
+    assert "recovery_hint" in error_events[0]
+
+
+# ----- instance_try / instance_ok / instance_fail progress events (v1.8.0) -----
+#
+# These events are emitted inside search_multi (not _run_single_query), so
+# we must let the real search_multi run and only mock urllib.request.urlopen.
+
+def _mock_urlopen_resp(data: bytes, content_type="application/json"):
+    """Build a MagicMock that quacks like an urlopen context manager."""
+    resp = MagicMock()
+    resp.read.return_value = data
+    resp.headers = {"Content-Type": content_type}
+    resp.__enter__.return_value = resp
+    resp.__exit__.return_value = None
+    return resp
+
+
+def _url_router(routing):
+    """Build a side_effect that dispatches urlopen by request URL substring."""
+    def _side_effect(req, *args, **kwargs):
+        url = getattr(req, "full_url", str(req))
+        for key, resp in routing.items():
+            if key in url:
+                if isinstance(resp, BaseException):
+                    raise resp
+                return resp
+        raise AssertionError(f"unexpected urlopen for {url!r}")
+    return _side_effect
+
+
+def test_progress_emits_instance_try_ok_fail(capsys):
+    """instance_try/instance_ok/instance_fail events are emitted to stderr.
+
+    Uses serial mode (parallel=False) so the events come out in a
+    deterministic order: try a -> fail a -> try b -> ok b.
+    """
+    set_progress_enabled(True)
+    try:
+        payload = json.dumps(
+            {"results": [{"title": "b", "url": "https://b.com"}]}
+        ).encode()
+        router = _url_router({
+            "a.example.com": urllib.error.URLError("down"),
+            "b.example.com": _mock_urlopen_resp(payload),
+        })
+        with patch("urllib.request.urlopen", side_effect=router):
+            search_mod.search_multi(
+                ["https://a.example.com", "https://b.example.com"],
+                {"q": "test", "format": "json"},
+                parallel=False, retry_per=0,
+            )
+        _, err = capsys.readouterr()
+        lines = [json.loads(l) for l in err.strip().split("\n") if l]
+        events = [e["event"] for e in lines]
+        assert "instance_try" in events
+        assert "instance_fail" in events
+        assert "instance_ok" in events
+        # instance_fail carries error_code
+        fail_events = [e for e in lines if e["event"] == "instance_fail"]
+        assert len(fail_events) >= 1
+        assert "error_code" in fail_events[0]
+        # instance_ok carries results count
+        ok_events = [e for e in lines if e["event"] == "instance_ok"]
+        assert len(ok_events) >= 1
+        assert "results" in ok_events[0]
+    finally:
+        set_progress_enabled(False)