diff --git a/backend/tests/AGENTS.md b/backend/tests/AGENTS.md
index 8ac1e6ae1..a95c58721 100644
--- a/backend/tests/AGENTS.md
+++ b/backend/tests/AGENTS.md
@@ -2,6 +2,23 @@
 
 Backend tests must preserve the runtime invariants they exercise without changing production execution topology.
 
+## Shared sandbox search contracts
+
+`test_sandbox_search_contract.py` runs shared `ls`/`glob`/`grep` scenarios through
+Local, AIO, E2B, BoxLite, Tenki and OpenSandbox adapters. POSIX shell transports
+execute production commands against temporary files; AIO file RPCs use an
+independent filesystem-backed double. Do not substitute precomputed final search
+results or import another test module's private fixtures. Provisioning, live SDK
+compatibility, permissions enforced above Sandbox, and session lifecycle remain
+in their existing suites. Windows skips this POSIX execution tier explicitly.
+
+Compare result names/content, errors and completeness, allowing documented root
+entries and directory suffixes to differ. First-stage cases use ordinary roots,
+positive caps and a plain literal pattern: ignored-root fixes (#5667), E2B literal
+metacharacters (#5627), and exactly-full local caps (#5491) have separate owners.
+Add those shared scenarios after their fixes land; do not encode known bugs as
+expected successful behavior or hide them with permanent xfails.
+
 ## External system-role admission
 
 `poc_external_system_message_injection.py --help` is the opt-in live reproduction
diff --git a/backend/tests/test_sandbox_search_contract.py b/backend/tests/test_sandbox_search_contract.py
new file mode 100644
index 000000000..6b1724c82
--- /dev/null
+++ b/backend/tests/test_sandbox_search_contract.py
@@ -0,0 +1,246 @@
+"""Shared search semantics through real providers and offline execution seams.
+
+Shell-backed providers run their production command strings with local sh/find/
+grep. AIO's file RPC seam reads the same fixture tree independently. This does
+not test a live SDK/server, shell-session lifecycle, or provider provisioning.
+"""
+
+from __future__ import annotations
+
+import glob as filesystem_glob
+import os
+import re
+import shutil
+import subprocess
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+from deerflow.sandbox.local.local_sandbox import LocalSandbox
+
+PROVIDERS = ("local", "aio", "e2b", "boxlite", "tenki", "opensandbox")
+REMOTE_PROVIDERS = tuple(name for name in PROVIDERS if name != "local")
+SHELL_SEARCH_PROVIDERS = ("e2b", "boxlite", "tenki", "opensandbox")
+pytestmark = pytest.mark.skipif(
+    os.name == "nt" or any(shutil.which(name) is None for name in ("sh", "find", "grep", "head")),
+    reason="offline provider search contract requires a POSIX shell and search utilities",
+)
+
+
+class _Transport:
+    """Execution/RPC replacement; never returns precomputed contract answers."""
+
+    def __init__(self, tmp_path: Path):
+        self.tmp_path = tmp_path
+        self.env = os.environ.copy()
+        self.error: OSError | None = None
+
+    def check(self, path: str | None = None):
+        if self.error is not None:
+            raise self.error
+        if path is not None and not Path(path).exists():
+            raise FileNotFoundError(path)
+
+    def shell(self, command: str, **_kwargs):
+        self.check()
+        result = subprocess.run(["sh", "-c", command], capture_output=True, text=True, env=self.env, timeout=10, check=False)
+        return SimpleNamespace(stdout=result.stdout, stderr=result.stderr, stdout_text=result.stdout, stderr_text=result.stderr, exit_code=result.returncode)
+
+    def aio_shell(self, *, command: str, **kwargs):
+        result = self.shell(command, **kwargs)
+        return SimpleNamespace(data=SimpleNamespace(output=result.stdout, exit_code=result.exit_code))
+
+    def opensandbox_shell(self, command: str, **kwargs):
+        result = self.shell(command, **kwargs)
+        return SimpleNamespace(logs=SimpleNamespace(stdout=[SimpleNamespace(text=result.stdout)], stderr=[]), exit_code=result.exit_code, error=None)
+
+    def missing_program(self, name: str):
+        directory = self.tmp_path / "unavailable-program"
+        directory.mkdir()
+        program = directory / name
+        program.write_text("#!/bin/sh\nexit 127\n", encoding="utf-8")
+        program.chmod(0o755)
+        self.env["PATH"] = str(directory) + os.pathsep + self.env.get("PATH", "")
+
+    def find_files(self, *, path: str, glob: str):
+        self.check(path)
+        # Python's filesystem glob is independent of DeerFlow's path_matches.
+        matches = sorted(p for p in filesystem_glob.glob(filesystem_glob.escape(str(Path(path))) + "/" + glob, recursive=True) if Path(p).is_file())
+        return SimpleNamespace(data=SimpleNamespace(files=matches))
+
+    def list_path(self, *, path: str, recursive: bool, show_hidden: bool):
+        self.check(path)
+        assert recursive and not show_hidden
+        return SimpleNamespace(data=SimpleNamespace(files=[SimpleNamespace(path=str(p)) for p in sorted(Path(path).rglob("*")) if not p.name.startswith(".")]))
+
+    def grep_files(self, *, path: str, pattern: str, case_insensitive: bool, fixed_strings: bool, max_results: int, max_file_size: str, recursive: bool):
+        self.check(path)
+        assert recursive and max_file_size == "1M"
+        matcher = re.compile(re.escape(pattern) if fixed_strings else pattern, re.IGNORECASE if case_insensitive else 0)
+        root = Path(path)
+        files = [root] if root.is_file() else sorted(p for p in root.rglob("*") if p.is_file())
+        matches = []
+        for file in files:
+            for number, line in enumerate(file.read_text(encoding="utf-8").splitlines(), 1):
+                if matcher.search(line):
+                    matches.append(SimpleNamespace(file=str(file), line_number=number, line_content=line))
+        return SimpleNamespace(data=SimpleNamespace(matches=matches[:max_results], truncated=len(matches) > max_results))
+
+
+@pytest.fixture(params=PROVIDERS)
+def provider(request, tmp_path, monkeypatch):
+    name = request.param
+    transport = _Transport(tmp_path)
+    if name == "local":
+        sandbox = LocalSandbox("search-contract")
+    elif name == "aio":
+        from deerflow.community.aio_sandbox import aio_sandbox as module
+
+        client = SimpleNamespace(file=transport, shell=SimpleNamespace(exec_command=transport.aio_shell))
+        monkeypatch.setattr(module, "AioSandboxClient", lambda **kwargs: client)
+        monkeypatch.setattr(module, "sandbox_http_trust_env", lambda _url: True)
+        sandbox = module.AioSandbox("search-contract", "http://127.0.0.1:1", home_dir=str(tmp_path))
+    elif name == "e2b":
+        from deerflow.community.e2b_sandbox.e2b_sandbox import E2BSandbox
+
+        sandbox = E2BSandbox("search-contract", SimpleNamespace(commands=SimpleNamespace(run=transport.shell)))
+    elif name == "boxlite":
+        from deerflow.community.boxlite.box import BoxliteBox
+
+        sandbox = BoxliteBox("search-contract", SimpleNamespace(), run=None)
+        monkeypatch.setattr(sandbox, "_sh", transport.shell)
+    elif name == "tenki":
+        from deerflow.community.tenki.sandbox import TenkiSandbox
+
+        sandbox = TenkiSandbox("search-contract", SimpleNamespace())
+        monkeypatch.setattr(sandbox, "_sh", transport.shell)
+    elif name == "opensandbox":
+        from deerflow.community.opensandbox.sandbox import OpenSandboxSandbox
+
+        sandbox = OpenSandboxSandbox("search-contract", SimpleNamespace(), run_command_opts_cls=SimpleNamespace)
+        monkeypatch.setattr(sandbox, "_run", transport.opensandbox_shell)
+    else:
+        raise AssertionError(f"Unregistered contract provider: {name}")
+    return SimpleNamespace(name=name, sandbox=sandbox, transport=transport)
+
+
+@pytest.fixture
+def tree(tmp_path):
+    root = tmp_path / "project [one]'s 中文"
+    root.mkdir()
+    (root / "nested").mkdir()
+    (root / "node_modules").mkdir()
+    (root / "-résumé '中文'.txt").write_text("header\nneedle exact\nNeedle upper\n", encoding="utf-8")
+    (root / "nested" / "result.txt").write_text("needle nested\n", encoding="utf-8")
+    (root / "node_modules" / "dependency.txt").write_text("needle ignored\n", encoding="utf-8")
+    return root
+
+
+def _relative_paths(paths, root):
+    # Directory suffixes and inclusion of the requested root are legitimate
+    # provider presentation differences; names and descendants must agree.
+    return {Path(path.rstrip("/")).relative_to(root).as_posix() for path in paths if Path(path.rstrip("/")) != root}
+
+
+def _call(sandbox, operation, root):
+    if operation == "ls":
+        return sandbox.list_dir(str(root))
+    if operation == "glob":
+        return sandbox.glob(str(root), "**/*.txt")
+    return sandbox.grep(str(root), "needle")
+
+
+def test_listing_preserves_paths_and_ignores_descendants(provider, tree):
+    assert _relative_paths(provider.sandbox.list_dir(str(tree)), tree) == {"-résumé '中文'.txt", "nested", "nested/result.txt"}
+
+
+def test_glob_preserves_paths_and_ignores_descendants(provider, tree):
+    matches, truncated = provider.sandbox.glob(str(tree), "**/*.txt")
+    assert _relative_paths(matches, tree) == {"-résumé '中文'.txt", "nested/result.txt"}
+    assert truncated is False
+
+
+def test_glob_can_include_directories(provider, tree):
+    matches, truncated = provider.sandbox.glob(str(tree), "**/nested", include_dirs=True)
+    assert _relative_paths(matches, tree) == {"nested"}
+    assert truncated is False
+
+
+def test_grep_preserves_line_numbers_and_ignores_descendants(provider, tree):
+    matches, truncated = provider.sandbox.grep(str(tree), "needle", case_sensitive=True)
+    assert {(Path(m.path).relative_to(tree).as_posix(), m.line_number, m.line) for m in matches} == {
+        ("-résumé '中文'.txt", 2, "needle exact"),
+        ("nested/result.txt", 1, "needle nested"),
+    }
+    assert truncated is False
+
+
+def test_grep_case_insensitive_and_file_scope(provider, tree):
+    file = tree / "-résumé '中文'.txt"
+    matches, truncated = provider.sandbox.grep(str(file), "needle", literal=True)
+    assert {(m.path, m.line_number) for m in matches} == {(str(file), 2), (str(file), 3)}
+    assert truncated is False
+
+
+def test_grep_glob_filter_is_root_relative(provider, tree):
+    matches, truncated = provider.sandbox.grep(str(tree), "needle", glob="nested/*.txt")
+    assert [(m.path, m.line_number) for m in matches] == [(str(tree / "nested" / "result.txt"), 1)]
+    assert truncated is False
+
+
+def test_no_match_is_empty_and_complete(provider, tree):
+    assert provider.sandbox.glob(str(tree), "**/*.missing") == ([], False)
+    assert provider.sandbox.grep(str(tree), "absentneedle") == ([], False)
+
+
+def test_existing_empty_directory_is_not_an_error(provider, tmp_path):
+    root = tmp_path / "empty"
+    root.mkdir()
+    assert _relative_paths(provider.sandbox.list_dir(str(root)), root) == set()
+    assert provider.sandbox.glob(str(root), "**/*.txt") == ([], False)
+    assert provider.sandbox.grep(str(root), "needle") == ([], False)
+
+
+@pytest.mark.parametrize("operation", ["ls", "glob", "grep"])
+def test_missing_root_is_not_an_empty_result(provider, tmp_path, operation):
+    with pytest.raises(FileNotFoundError):
+        _call(provider.sandbox, operation, tmp_path / "missing")
+
+
+def test_invalid_regex_is_rejected(provider, tree):
+    with pytest.raises(re.error):
+        provider.sandbox.grep(str(tree), "[invalid")
+
+
+@pytest.mark.parametrize("operation", ["glob", "grep"])
+def test_a_dropped_eligible_match_reports_truncation(provider, tmp_path, operation):
+    root = tmp_path / "results"
+    root.mkdir()
+    for number in range(3):
+        (root / f"result{number}.txt").write_text("needle\n", encoding="utf-8")
+    if operation == "glob":
+        matches, truncated = provider.sandbox.glob(str(root), "**/*.txt", max_results=2)
+    else:
+        matches, truncated = provider.sandbox.grep(str(root), "needle", max_results=2)
+    assert len(matches) == 2
+    assert truncated is True
+
+
+@pytest.mark.parametrize("provider", REMOTE_PROVIDERS, indirect=True)
+@pytest.mark.parametrize("operation", ["ls", "glob", "grep"])
+def test_transport_failure_does_not_become_no_matches(provider, tree, operation):
+    provider.transport.error = OSError("synthetic transport failure")
+    with pytest.raises(OSError):
+        _call(provider.sandbox, operation, tree)
+
+
+@pytest.mark.parametrize(
+    ("provider", "operation", "program"),
+    [(name, "ls", "find") for name in REMOTE_PROVIDERS] + [(name, operation, program) for name in SHELL_SEARCH_PROVIDERS for operation, program in (("glob", "find"), ("grep", "grep"))],
+    indirect=["provider"],
+)
+def test_missing_search_program_does_not_become_no_matches(provider, tree, operation, program):
+    provider.transport.missing_program(program)
+    with pytest.raises(OSError):
+        _call(provider.sandbox, operation, tree)