cli/display: render web_search as a pretty line

``web_search`` is composed by the CLI host rather than the builtin catalog, so it had no ``_PRETTY_LINES`` entry and fell back to the ``[tool] …`` / ``[tool ok] …`` whole lines. It now leads with ``* Web Search '<query>' `` (the query as a 60-character preview, like the ask and skill subjects) and lands on the hit count — or on ``(no results)`` when every source came up empty, an emptiness the tool reports as ``error: the search found nothing`` and which is therefore not shown as a failure. A real error still prints in red with its message.

The guard test that keeps a builtin tool from shipping without a renderer now checks this host-composed tool too, since a catalog walk cannot see it.

src/plyngent/cli/display.py

@@ -423,6 +423,27 @@ def _fetch_detail(_args_json: str, result: str) -> str:
     return _pretty_segments((f"({status or 'done'})", _http_status_fg(status)))
 
 
+# ``web_search`` reports "every source found nothing (or failed)" as an error, so
+# the renderer splits that emptiness off the failures that are real errors.
+_WEB_SEARCH_EMPTY = "error: the search found nothing"
+
+
+def _web_search_prefix(args_json: str) -> str:
+    query = _json_str_arg(args_json, "query") or "?"
+    return _pretty_prefix(f"* Web Search '{_preview(query, _ASK_SUBJECT_PREVIEW)}' ")
+
+
+def _web_search_detail(_args_json: str, result: str) -> str:
+    """``web_search`` outcome: hit count, nothing found, or a failing source."""
+    if result.startswith(_WEB_SEARCH_EMPTY):
+        return _pretty_segments(("(no results)", "dim"))
+    if result.startswith("error:"):
+        return _pretty_segments((f"({result})", "red"))
+    hits = sum(1 for line in result.splitlines() if line.startswith("- "))
+    unit = "hit" if hits == 1 else "hits"
+    return _pretty_segments((f"({hits} {unit})", None))
+
+
 _MUTATOR_VERBS: dict[str, str] = {
     "edit_replace": "Edit",
     "edit_lineno": "Edit",
@@ -825,6 +846,7 @@ _PRETTY_LINES: dict[str, PrettyLine] = {
     "run_argv": PrettyLine(prefix=_run_argv_prefix, detail=_run_argv_detail),
     "run_argv_batch": PrettyLine(prefix=_run_argv_batch_prefix, detail=_run_argv_batch_detail),
     "fetch": PrettyLine(prefix=_fetch_prefix, detail=_fetch_detail),
+    "web_search": PrettyLine(prefix=_web_search_prefix, detail=_web_search_detail),
     "edit_replace": _mutator_line("edit_replace"),
     "edit_lineno": _mutator_line("edit_lineno"),
     "write_file": _mutator_line("write_file"),

tests/test_cli/test_display.py

@@ -509,6 +509,42 @@ async def test_pretty_fetch_error(capsys: pytest.CaptureFixture[str]) -> None:
     assert "* Fetch GET https://example.com (error: fetch failed: boom)" in out
 
 
+async def test_pretty_web_search(capsys: pytest.CaptureFixture[str]) -> None:
+    result = (
+        "- CPython free-threading — https://example.com/ft\n"
+        "  PEP 703 landed in 3.13\n"
+        "- Another page — https://example.com/other\n"
+    )
+    call = _pretty_call("web_search", '{"query": "python 3.14 free-threading"}')
+    await render_events(_aiter([call, _result(result)]))
+    out = capsys.readouterr().out
+    assert "* Web Search 'python 3.14 free-threading' (2 hits)" in out
+    assert "[tool]" not in out
+    assert "[tool ok]" not in out
+
+
+async def test_pretty_web_search_truncates_the_query(capsys: pytest.CaptureFixture[str]) -> None:
+    query = "a" * 80
+    await render_events(
+        _aiter([_pretty_call("web_search", f'{{"query": "{query}"}}'), _result("- One — https://example.com\n")])
+    )
+    out = capsys.readouterr().out
+    assert f"* Web Search '{'a' * 60}…' (1 hit)" in out
+
+
+async def test_pretty_web_search_no_results(capsys: pytest.CaptureFixture[str]) -> None:
+    result = "error: the search found nothing (DeepseekSearchBackend: no results; BingSearchBackend: no results)"
+    await render_events(_aiter([_pretty_call("web_search", '{"query": "zzz"}'), _result(result)]))
+    out = capsys.readouterr().out
+    assert "* Web Search 'zzz' (no results)" in out
+
+
+async def test_pretty_web_search_failing_source(capsys: pytest.CaptureFixture[str]) -> None:
+    await render_events(_aiter([_pretty_call("web_search", '{"query": "x"}'), _result("error: search HTTP 401")]))
+    out = capsys.readouterr().out
+    assert "* Web Search 'x' (error: search HTTP 401)" in out
+
+
 async def test_pretty_mutators(capsys: pytest.CaptureFixture[str]) -> None:
     cases = [
         ("write_file", '{"path": "src/x.py"}', "wrote 120 characters to src/x.py", "* Write 'src/x.py' (120 chars)"),
@@ -862,8 +898,13 @@ async def test_pretty_mcp_tools_use_one_generic_line(capsys: pytest.CaptureFixtu
 def test_every_builtin_tool_has_a_pretty_line() -> None:
     """A new builtin tool must ship a renderer, or it silently loses the syntax."""
     from plyngent.tools.catalog import default_tool_definitions
+    from plyngent.tools.net.search import WEB_SEARCH_TOOL_NAME
 
-    missing = [d.name for d in default_tool_definitions() if _pretty_line_for(d.name) is None]
+    names = [d.name for d in default_tool_definitions()]
+    # The CLI host composes ``web_search`` over the builtins, so a catalog walk
+    # on its own would let a renderer-less tool ship.
+    names.append(WEB_SEARCH_TOOL_NAME)
+    missing = [name for name in names if _pretty_line_for(name) is None]
     assert missing == []