Improve web search region selection and normalize provider resultsHEADmain

Update ddgs to 9.16.0 and keep backend="auto" while preserving the
LLM-facing query/max_results inputs and title/href/body result schema.

Implementation:
- Add OLLAMA_WEB_SEARCH_REGION with auto/us-en/jp-jp values, normalized
  configuration input, and a clear startup error for unsupported values.
- In auto mode, detect kana after NFKC normalization and exclusion of URLs
  and site:/filetype: tokens. Select jp-jp for kana and us-en otherwise,
  without modifying the original query or sharing per-call region state.
- Preserve href/url and body/snippet fallbacks and normalize None values.
- Reject malformed HTTP(S) URLs without DNS lookups or extra requests.
- Unwrap known Yahoo redirect URLs before excluding Bing aclick ads.
- Represent missing and URL-only titles as empty strings rather than
  inventing titles from snippets. Preserve remaining provider order and
  allow fewer results after filtering, without additional searches.
- Preserve provider exception propagation and identify ddgs in error logs.

Coverage and documentation:
- Add 72 regression cases for configuration, region routing, concurrency,
  public schemas, title/URL/ad boundaries, limits, and search_and_fetch
  continuation. Update existing provider mocks and log assertions.
- Document the region environment setting and result semantics in both
  READMEs and tools-schema.md; update the changelog.
- Keep only a short backend availability caveat in tools-schema.md and
  remove the temporary backend comparison, design, and validation docs.

Validation:
- pytest: 222 passed; ruff check . and mypy src/ passed.
- uv lock --check and git diff --check passed.
- Initial live acceptance: 56 searches plus 3 registry smoke checks;
  default-region auto succeeded 8/18 times and real ad filtering removed
  two ads. Stable relevance/title quality targets remain unmet because
  provider acquisition is unreliable.
- Follow-up backend study: 234 comparative searches plus 3 Yahoo response
  diagnostics. Yahoo led individual backends at 9/18; restricted multi-
  backend combinations did not outperform the contemporaneous auto
  control. Authentication, access restrictions, temporary upstream
  failures, and Yahoo HTML/parser mismatches were observed.

Do not claim search reliability is fixed or add backend configuration,
custom retries, ranking changes, or challenge bypasses. Running app
processes were not restarted; restart is needed to load the changes.

3 files changed, 293 insertions, 6 deletions

diff --git a/tests/test_logging.py b/tests/test_logging.py
index ef6fbd2..68aeb97 100644
--- a/tests/test_logging.py
+++ b/tests/test_logging.py
@@ -73,7 +73,7 @@ def test_web_search_provider_error_is_written_to_server_log(
         def __exit__(self, *args):
             return None
 
-        def text(self, query, max_results=5):
+        def text(self, query, max_results=5, *, region, backend):
             raise RuntimeError("403 Forbidden")
 
     with patch("ollama_web.tools.search.DDGS", FailingDDGS), TestClient(create_app()):
@@ -83,6 +83,6 @@ def test_web_search_provider_error_is_written_to_server_log(
 
     assert result == {"error": "RuntimeError: 403 Forbidden"}
     content = (data_dir / "server.log").read_text(encoding="utf-8")
-    assert "DuckDuckGo web search failed" in content
+    assert "ddgs web search failed" in content
     assert "RuntimeError: 403 Forbidden" in content
     assert "private search terms" not in content
diff --git a/tests/test_search.py b/tests/test_search.py
new file mode 100644
index 0000000..77f6ee4
--- /dev/null
+++ b/tests/test_search.py
@@ -0,0 +1,285 @@
+"""Search policy and result-boundary regression tests (no live network)."""
+
+import json
+import socket
+import subprocess
+import sys
+from concurrent.futures import ThreadPoolExecutor
+from threading import Barrier
+from urllib.parse import quote
+
+import pytest
+from ollama._utils import convert_function_to_tool
+
+from ollama_web.config import Settings, settings
+from ollama_web.tools import search
+from ollama_web.tools.helper.pagination import parse_paged_result
+from ollama_web.tools.registry import default_registry
+
+
+@pytest.fixture
+def provider(monkeypatch):
+    calls = []
+    rows = [{"title": "Recipe", "href": "https://example.com/recipe", "body": "Summary"}]
+
+    class FakeDDGS:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *args):
+            pass
+
+        def text(self, query, **kwargs):
+            calls.append((query, kwargs))
+            return rows
+
+    monkeypatch.setattr(search, "DDGS", FakeDDGS)
+    monkeypatch.setattr(settings, "search_region", "auto")
+    return calls, rows
+
+
+@pytest.mark.parametrize(
+    "value,expected",
+    [
+        (None, "auto"),
+        ("auto", "auto"),
+        ("us-en", "us-en"),
+        ("jp-jp", "jp-jp"),
+        (" JP-JP ", "jp-jp"),
+    ],
+)
+def test_region_setting(monkeypatch, value, expected):
+    monkeypatch.delenv("OLLAMA_WEB_SEARCH_REGION", raising=False)
+    if value is not None:
+        monkeypatch.setenv("OLLAMA_WEB_SEARCH_REGION", value)
+    assert Settings().search_region == expected
+
+
+@pytest.mark.parametrize("value", ["", "ja", "jp", "en-US", "jp-ja"])
+def test_invalid_region_setting(monkeypatch, value):
+    monkeypatch.setenv("OLLAMA_WEB_SEARCH_REGION", value)
+    with pytest.raises(ValueError, match="OLLAMA_WEB_SEARCH_REGION.*auto, us-en, jp-jp"):
+        Settings()
+
+
+def test_invalid_region_fails_at_import(monkeypatch):
+    monkeypatch.setenv("OLLAMA_WEB_SEARCH_REGION", "invalid")
+    process = subprocess.run(
+        [sys.executable, "-c", "import ollama_web.config"], capture_output=True, text=True
+    )
+    assert process.returncode != 0
+    assert "OLLAMA_WEB_SEARCH_REGION must be one of: auto, us-en, jp-jp" in process.stderr
+
+
+@pytest.mark.parametrize(
+    "query,region",
+    [
+        ("カレー おすすめ レシピ", "jp-jp"),
+        ("引越し 費用 相場", "jp-jp"),
+        ("ｶﾚｰ ﾚｼﾋﾟ", "jp-jp"),
+        ("best curry recipe", "us-en"),
+        ("東京 天気", "us-en"),
+        ("北京 天气", "us-en"),
+        ("рецепт карри", "us-en"),
+        ("curry レシピ", "jp-jp"),
+        ("カレー site:cookpad.com filetype:pdf", "jp-jp"),
+        ("recipe https://example.com/カレー", "us-en"),
+        ("recipe WWW.example.com/レシピ", "us-en"),
+        ("recipe SITE:レシピ.example -filetype:カレー", "us-en"),
+        ("recipe https://example.com/カレー おすすめ", "jp-jp"),
+    ],
+)
+def test_region_and_original_query(provider, query, region):
+    calls, _ = provider
+    search.web_search(query, 2)
+    assert calls == [(query, {"max_results": 2, "region": region, "backend": "auto"})]
+
+
+@pytest.mark.parametrize("region,query", [("us-en", "カレー"), ("jp-jp", "best curry recipe")])
+def test_fixed_region_overrides_query(provider, monkeypatch, region, query):
+    monkeypatch.setattr(settings, "search_region", region)
+    search.web_search(query)
+    assert provider[0][0][1]["region"] == region
+
+
+@pytest.mark.parametrize("query", ["", " \n\t"])
+def test_empty_query_does_not_search(provider, query):
+    assert search.web_search(query) == []
+    assert provider[0] == []
+
+
+def test_concurrent_regions_are_local(monkeypatch):
+    barrier = Barrier(2)
+    monkeypatch.setattr(settings, "search_region", "auto")
+
+    class ConcurrentDDGS:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *args):
+            pass
+
+        def text(self, query, **kwargs):
+            barrier.wait(timeout=5)
+            return [{"title": kwargs["region"], "href": "https://example.com", "body": query}]
+
+    monkeypatch.setattr(search, "DDGS", ConcurrentDDGS)
+    with ThreadPoolExecutor(max_workers=2) as executor:
+        results = list(executor.map(search.web_search, ["カレー", "curry"]))
+    assert [r[0]["title"] for r in results] == ["jp-jp", "us-en"]
+    assert settings.search_region == "auto"
+
+
+@pytest.mark.parametrize(
+    "title,expected",
+    [
+        (None, ""),
+        ("", ""),
+        ("  ", ""),
+        ("Recipe", "Recipe"),
+        ("https://www.example.com/カレー/", ""),
+        ("www.example.com/カレー", ""),
+        ("example.com/%E3%82%AB%E3%83%AC%E3%83%BC/", ""),
+        ("https://other.example/recipe", ""),
+        ("other.example/recipe", ""),
+        ("example.com の使い方", "example.com の使い方"),
+        ("Recipe at example.com", "Recipe at example.com"),
+        ("Python3.12", "Python3.12"),
+        ("v9.16.0", "v9.16.0"),
+    ],
+)
+def test_title_semantics(provider, title, expected):
+    _, rows = provider
+    rows[:] = [
+        {"title": title, "href": "https://www.example.com/カレー/", "body": "A real summary"}
+    ]
+    assert search.web_search("recipe") == [
+        {"title": expected, "href": "https://www.example.com/カレー/", "body": "A real summary"}
+    ]
+
+
+@pytest.mark.parametrize(
+    "url",
+    [
+        None,
+        "",
+        "/relative",
+        "javascript:alert(1)",
+        "ftp://example.com/file",
+        "https:///path",
+        "https://bad host.example",
+        "https://[invalid",
+        "https://example.com:bad",
+        "https://example.com:99999",
+        "https://example..com",
+        "https://example.com/\npath",
+    ],
+)
+def test_invalid_url_is_omitted(provider, url):
+    provider[1][:] = [{"title": "Invalid", "href": url}]
+    assert search.web_search("recipe") == []
+    assert len(provider[0]) == 1
+
+
+def test_fallbacks_and_no_extra_network(provider, monkeypatch):
+    def unexpected(*args, **kwargs):
+        raise AssertionError("Search normalization must not resolve or fetch URLs")
+
+    monkeypatch.setattr(socket, "getaddrinfo", unexpected)
+    provider[1][:] = [
+        {
+            "title": None,
+            "href": None,
+            "url": "https://example.com/a",
+            "body": None,
+            "snippet": "Fallback",
+        }
+    ]
+    assert search.web_search("recipe") == [
+        {"title": "", "href": "https://example.com/a", "body": "Fallback"}
+    ]
+
+
+@pytest.mark.parametrize(
+    "href,expected",
+    [
+        ("https://bing.com/aclick?u=ad", None),
+        ("https://www.bing.com/aclick?u=ad", None),
+        ("https://www.bing.com./aclick?u=ad", None),
+        (
+            "https://r.search.yahoo.com/a/RU="
+            + quote("https://www.bing.com/aclick?u=ad", safe="")
+            + "/RK=2/RS=x",
+            None,
+        ),
+        (
+            "https://r.search.yahoo.com/a/RU="
+            + quote("https://example.com/article?q=1", safe="")
+            + "/RK=2/RS=x",
+            "https://example.com/article?q=1",
+        ),
+        ("https://r.search.yahoo.com/a/RU=javascript%3Aalert(1)/RK=2", None),
+        ("https://www.bing.com/search?q=curry", "https://www.bing.com/search?q=curry"),
+        ("https://example.com/RU=article/RK=2", "https://example.com/RU=article/RK=2"),
+        ("https://r.search.yahoo.com/article", "https://r.search.yahoo.com/article"),
+    ],
+)
+def test_known_ad_and_wrapper_boundaries(provider, href, expected):
+    provider[1][:] = [{"title": "Article", "href": href, "body": "Summary"}]
+    result = search.web_search("article")
+    assert [r["href"] for r in result] == ([] if expected is None else [expected])
+
+
+@pytest.mark.parametrize("limit,expected", [(None, 2), (0, 2), (-1, 2), (1, 1), (3, 3)])
+def test_limits_and_order(provider, monkeypatch, limit, expected):
+    monkeypatch.setattr(settings, "search_max_results", 2)
+    provider[1][:] = [{"title": str(i), "href": f"https://example.com/{i}"} for i in range(4)]
+    assert [r["title"] for r in search.web_search("recipe", limit)] == [
+        str(i) for i in range(expected)
+    ]
+    assert provider[0][0][1]["max_results"] == expected
+
+
+def test_omitted_results_do_not_trigger_retry(provider):
+    provider[1][:] = [
+        {"href": "https://bing.com/aclick?u=ad"},
+        {"title": "Kept", "href": "https://example.com/article"},
+    ]
+    assert len(search.web_search("recipe", 5)) == 1
+    assert len(provider[0]) == 1
+
+
+def test_public_schema_and_registry_result(provider):
+    schema = convert_function_to_tool(search.web_search).function.parameters
+    assert set(schema.properties) == {"query", "max_results"}
+    assert schema.required == ["query"]
+    results = json.loads(default_registry().execute("web_search", {"query": "カレー"}))
+    assert set(results[0]) == {"title", "href", "body"}
+    assert provider[0][0][1]["region"] == "jp-jp"
+
+
+def test_search_and_fetch_uses_cleaned_candidates_and_continues(provider, monkeypatch):
+    from ollama_web.tools import fetch
+
+    provider[1][:] = [
+        {"href": "https://bing.com/aclick?u=ad"},
+        {"title": "https://example.com/a.txt", "href": "https://example.com/a.txt"},
+        {"title": "B", "href": "https://example.com/b.txt"},
+    ]
+    monkeypatch.setattr(
+        fetch,
+        "fetch_public_bytes",
+        lambda url, timeout=None: (
+            ("FIRST" if url.endswith("a.txt") else "SECOND").encode(),
+            url,
+            "text/plain",
+        ),
+    )
+    first = fetch.search_and_fetch("カレー", "txt", max_results=2)
+    body, has_more, token = parse_paged_result(first)
+    assert "FIRST" in body and has_more and token
+    second = fetch.search_and_fetch("カレー", "txt", continue_from=token)
+    assert "SECOND" in parse_paged_result(second)[0]
+    assert provider[0] == [
+        ("カレー filetype:txt", {"max_results": 4, "region": "jp-jp", "backend": "auto"})
+    ]
diff --git a/tests/test_tools.py b/tests/test_tools.py
index 6ba537b..487ce98 100644
--- a/tests/test_tools.py
+++ b/tests/test_tools.py
@@ -103,7 +103,9 @@ def test_web_search_mocked():
         def __exit__(self, *a):
             return None
 
-        def text(self, q, max_results=5):
+        def text(self, q, max_results=5, *, region, backend):
+            assert region == "us-en"
+            assert backend == "auto"
             return fake
 
     monkey = MagicMock()
@@ -126,7 +128,7 @@ def test_web_search_returns_empty_list_for_no_provider_results() -> None:
         def __exit__(self, *args):
             return None
 
-        def text(self, query, max_results=5):
+        def text(self, query, max_results=5, *, region, backend):
             return []
 
     with patch.object(search_mod, "DDGS", EmptyDDGS):
@@ -145,7 +147,7 @@ def test_web_search_logs_and_propagates_provider_errors(
         def __exit__(self, *args):
             return None
 
-        def text(self, query, max_results=5):
+        def text(self, query, max_results=5, *, region, backend):
             raise RuntimeError("403 Forbidden")
 
     with (
@@ -155,7 +157,7 @@ def test_web_search_logs_and_propagates_provider_errors(
         with pytest.raises(RuntimeError, match="403 Forbidden"):
             search_mod.web_search("private search terms")
 
-    assert "DuckDuckGo web search failed" in caplog.text
+    assert "ddgs web search failed" in caplog.text
     assert "private search terms" not in caplog.text
 
     registry = ToolRegistry()