[eric] security: mirror the executor sandbox gate into the public edge, with a drift test

backend/tests/test_edge_sandbox_mirrors_backend.py

@@ -0,0 +1,29 @@
+"""The public edge vendors the desktop sandbox's static gate, and a gate that
+only gets tightened on the desktop leaves the internet-facing copy open. So the
+two files must stay byte-identical below their docstrings; SECURITY.md has
+carried "drift risk" as an open note on this pair since the edge shipped.
+
+Run:
+    backend/.venv/bin/python -m pytest backend/tests/test_edge_sandbox_mirrors_backend.py -v
+"""
+
+import ast
+from pathlib import Path
+
+P_ROOT = Path(__file__).resolve().parents[2]
+P_DESKTOP = P_ROOT / "backend" / "apps" / "outputs" / "code_safety.py"
+P_EDGE = P_ROOT / "openswarm-edge" / "app" / "code_safety.py"
+
+
+def p_body(path: Path) -> str:
+    """The file with its module docstring (the only licensed difference) removed."""
+    source = path.read_text()
+    docstring = ast.parse(source).body[0]
+    return "".join(source.splitlines(keepends=True)[docstring.end_lineno:])
+
+
+def test_edge_gate_is_a_verbatim_copy_of_the_desktop_gate() -> None:
+    assert p_body(P_EDGE) == p_body(P_DESKTOP), (
+        "openswarm-edge/app/code_safety.py has drifted from "
+        "backend/apps/outputs/code_safety.py; re-copy it below the docstring."
+    )

linter/config/config.json

@@ -19,7 +19,7 @@
     "eslint-knip": "Node tooling deferred to a later pass.",
     "classes": "Placeholder check, not wired up. endpoints: orphaned-endpoint triage deferred.",
     "max-file-lines-exceptions": "Grandfather list of pre-existing >300-line files (existing debt, not new). Paths updated after the folder-tree restructure moved several of them. The two manager/prompt/* entries are from the agent_manager decomposition: prompt_context.py aggregates the system-prompt context builders and attachments.py is one cohesive 230-line attachment resolver; both are single-responsibility and a few lines over, not splittable without an artificial seam.",
-    "max-folder-items-exceptions": "Exact-path allow for folders intentionally over the cap. The rule trips at >7 (7 items is fine, the 8th tips it), so only genuinely 8+ folders are listed. backend/ and backend/apps are FastAPI feature-package registries (each child is an app mounted in main.py); agents/ aggregates agent subsystems; agents/manager/ is the agent_manager god-object decomposition (cohesive AgentManager mixins + standalone run helpers + the streaming/permissions/prompt/session subtrees), conventionally flat like agents/ and core/ since its standalone helpers are heterogeneous and don't group cleanly; agents/manager/streaming and agents/manager/session are flat peer collections of one-module-per-concern handlers; core/, tools_lib/, tests/ are conventionally flat. Frontend: app/pages is the page registry, AgentChat/ChatInput/Settings-sections/Onboarding are organizational parents, and shared/state (Redux slices) plus hooks/steps/mcp-cards/Views are flat peer collections. scripts/, electron/, linter/checks/ are flat tool dirs. These replaced blanket .lintignore-max-folder-items sentinels (backend, frontend, scripts, electron, linter/checks) so the rule still catches NEW unplanned bloat everywhere else. Kept as whole-subtree sentinels on purpose: debugger/ (self-contained injected sub-tool with its own Vite GUI), webapp_template (Vite scaffold payload), and vendored mcp-bundles. 2026-07 desktop-shell additions: Dashboard canvas/cards/desktop + hooks/interaction + hooks/lifecycle, AgentChat bubbles/tool-ui, and shared/styles are flat peer collections (one component or hook per concern) that crossed 7 as the redesign surface grew. frontend/src/toolui carries a whole-subtree .lintignore: vendored tool-ui component library (pierre), same treatment as mcp-bundles.",
+    "max-folder-items-exceptions": "Exact-path allow for folders intentionally over the cap. The rule trips at >7 (7 items is fine, the 8th tips it), so only genuinely 8+ folders are listed. backend/ and backend/apps are FastAPI feature-package registries (each child is an app mounted in main.py); agents/ aggregates agent subsystems; agents/manager/ is the agent_manager god-object decomposition (cohesive AgentManager mixins + standalone run helpers + the streaming/permissions/prompt/session subtrees), conventionally flat like agents/ and core/ since its standalone helpers are heterogeneous and don't group cleanly; agents/manager/streaming and agents/manager/session are flat peer collections of one-module-per-concern handlers; core/, tools_lib/, tests/ are conventionally flat. Frontend: app/pages is the page registry, AgentChat/ChatInput/Settings-sections/Onboarding are organizational parents, and shared/state (Redux slices) plus hooks/steps/mcp-cards/Views are flat peer collections. scripts/, electron/, linter/checks/ are flat tool dirs. These replaced blanket .lintignore-max-folder-items sentinels (backend, frontend, scripts, electron, linter/checks) so the rule still catches NEW unplanned bloat everywhere else. Kept as whole-subtree sentinels on purpose: debugger/ (self-contained injected sub-tool with its own Vite GUI), webapp_template (Vite scaffold payload), and vendored mcp-bundles. 2026-07 desktop-shell additions: Dashboard canvas/cards/desktop + hooks/interaction + hooks/lifecycle, AgentChat bubbles/tool-ui, and shared/styles are flat peer collections (one component or hook per concern) that crossed 7 as the redesign surface grew. frontend/src/toolui carries a whole-subtree .lintignore: vendored tool-ui component library (pierre), same treatment as mcp-bundles. openswarm-edge/app is the edge's flat one-module-per-concern set (routing, bundles, inject, ratelimit, sandbox, and the vendored code_safety gate); it crossed 7 when the sandbox's static gate was split out to mirror the desktop file byte for byte.",
     "import-cycles": "Flags RUNTIME circular imports only (SCC>1). Skips type-only imports (import type / export type) and dynamic import() since neither runs at module init, which is why the idiomatic Redux store<->hooks type cycle is not flagged. Frontend alias resolution comes from import-cycle-aliases. Zero cycles today; the check keeps it that way.",
     "ruff + pyright": "Ported from Haik's linter (haik/feat/ingest). ruff is narrowed to F401/F811/F841 (unused imports/redefs/locals) and intentionally DROPS Haik's ARG001/ARG002 (unused args): our SDK-callback signatures require unused params (can_use_tool/pre_tool_hook take a `context` they don't use) and we ban the `_unused` prefix, so ARG is noise here. pyright runs Haik's existence-only config (typeCheckingMode off) with reportAttributeAccessIssue ENABLED: the AgentManager behavior classes now inherit a typing-only AgentManagerProtocol base (manager/AgentManagerProtocol.py) that declares the composed __init__ state + cross-class methods, so the checker sees self.sessions etc. from inside a mixin. pyright caught real bugs: a dangling `_conns` ref + TWO broken lazy imports (`_load_all`/`_load` from outputs.py, renamed to load_all/load in workspace_io but the import sites weren't updated \u2014 App Builder workspace seeding/name-sync was silently failing in a try/except). The one grandfathered SURFACE file (handle_assistant_message) is the SDK-optional try/except-import boundary (TextBlock=object fallback defeats isinstance narrowing). Both grandfather pre-existing debt by file; the refactor surface is clean. Requires `ruff` + `pyright` on PATH (added to requirements-dev.txt); pyright's config expects the venv at backend/.venv.",
     "no-underscore-names + p-private": "Convention checks ported verbatim from Haik's linter (haik/feat/ingest): no-underscore-names bans leading-underscore names (a dead-code-tooling blind spot; use p_ for private), p-private enforces that p_-prefixed names are accessed only inside their owning file/class (cross-file/class use means the name should be public). Backend Python only. The exception lists grandfather pre-existing debt that landed with the workflows/analytics forward-ports (eric's 'don't mass-migrate untouched files' rule); the agent_manager refactor surface is clean. NOTE: Haik's full linter (his branch also adds pyright + ruff and runs a different enabled set) should eventually supersede this; these two were lifted to enforce the p_ conventions on eric/dev now. browser_cookies.py is excepted for `_fields_` only: a ctypes.Structure protocol name required by the ctypes metaclass, not our naming."
@@ -165,6 +165,7 @@
       "backend/apps/agents/manager/session",
       "backend/apps/agents/manager/streaming",
       "backend/apps/outputs",
+      "openswarm-edge/app",
       "backend/apps/tools_lib",
       "backend/apps/service",
       "backend/tests",

openswarm-edge/app/code_safety.py

@@ -0,0 +1,223 @@
+"""Static safety gate for published apps' backend.py compute.
+
+VENDORED, verbatim below this docstring, from backend/apps/outputs/code_safety.py
+(the desktop App Builder gate). test_edge_sandbox_mirrors_backend.py in the
+backend suite fails if the two drift, because a gate that is only tightened on
+the desktop leaves the internet-facing copy open.
+"""
+
+import ast
+import importlib
+import types
+from typing import Dict, List, Optional, Set
+
+# Modules backend code is allowed to import. This is not an OS-level jail, so keep the list to "data shaping" libraries; no I/O, no networking, no subprocess. It pairs with cwd=tempdir + minimal env so the blast radius stays small.
+ALLOWED_MODULES = frozenset({
+    "json", "math", "re", "datetime", "collections", "itertools",
+    "functools", "statistics", "decimal", "fractions", "random",
+    "string", "textwrap", "unicodedata", "csv", "copy", "enum",
+    "dataclasses", "typing", "abc", "numbers", "uuid", "hashlib",
+    "base64", "binascii", "operator", "heapq", "bisect", "array",
+})
+
+# Builtins that punch holes through the allowlist or do I/O. Most are also deleted off `builtins` inside the subprocess; exec/compile/__import__ can't be, because the import machinery runs on them.
+P_BLOCKED_BUILTINS = frozenset({
+    "exec", "eval", "compile", "__import__", "open", "input",
+    "breakpoint", "exit", "quit",
+})
+
+# These hand back a live namespace dict, which is every blocked name again through a different door. Warned about but never deleted: library code calls them constantly, and a scrubbed `builtins` would break `import csv` itself.
+P_NAMESPACE_BUILTINS = frozenset({"vars", "globals", "locals"})
+
+# Spell an attribute as a string and the AST can't read it, so these are allowed only with a plain literal that would have passed written out longhand.
+P_DYNAMIC_ATTR_BUILTINS = frozenset({"getattr", "setattr", "delattr"})
+
+# Modules the executor preamble binds into the user's namespace with no import. `json` stays usable (it is allowlisted anyway); these three were the free handles that made the whole allowlist decorative.
+P_SANDBOX_MODULE_HANDLES = frozenset({"sys", "io", "builtins"})
+
+# Dunders that hold a reference to nothing at all, and `if __name__ == "__main__"` is far too common to punish.
+P_INERT_DUNDERS = frozenset({"__name__", "__file__", "__doc__"})
+
+
+class UnsafeCodeError(Exception):
+    """Raised when the static gate rejects user-supplied backend code."""
+
+
+def p_is_dunder(name: str) -> bool:
+    return len(name) > 4 and name.startswith("__") and name.endswith("__")
+
+
+def p_dotted_chain(node: ast.expr) -> Optional[List[str]]:
+    """['json', 'codecs', 'open'] for `json.codecs.open`; None when the chain
+    doesn't start at a plain name."""
+    parts: List[str] = []
+    current: ast.expr = node
+    while isinstance(current, ast.Attribute):
+        parts.append(current.attr)
+        current = current.value
+    if not isinstance(current, ast.Name):
+        return None
+    parts.append(current.id)
+    parts.reverse()
+    return parts
+
+
+def p_resolved_module(chain: List[str], aliases: Dict[str, str]) -> Optional[str]:
+    """The name of the module an attribute chain resolves to, or None if it
+    resolves to something that isn't a module.
+
+    `json.codecs` is a module and `datetime.time` is a class, and only the live
+    object knows which; matching attribute names against a list of module names
+    would flag both. So resolve against the module actually imported. Safe to
+    import here because `aliases` only ever holds allowlisted stdlib roots.
+    """
+    root = aliases.get(chain[0])
+    if root is None:
+        return None
+    try:
+        value: object = importlib.import_module(root)
+        for attr in chain[1:]:
+            value = getattr(value, attr)
+    except Exception:
+        return None
+    return value.__name__ if isinstance(value, types.ModuleType) else None
+
+
+def p_module_aliases(tree: ast.Module) -> Dict[str, str]:
+    """Local name -> allowlisted module it holds. Plain assignment counts, so
+    `m = json` doesn't launder `m.codecs` past the chain check. Modules outside
+    the allowlist are never recorded, which is what keeps the resolver above
+    from importing anything a hostile file names."""
+    aliases: Dict[str, str] = {"json": "json"}
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                root = alias.name.split(".")[0]
+                if root in ALLOWED_MODULES:
+                    aliases[alias.asname or root] = root
+    assigns = [n for n in ast.walk(tree) if isinstance(n, ast.Assign)]
+    for _ in range(len(assigns)):
+        before = len(aliases)
+        for node in assigns:
+            if len(node.targets) != 1 or not isinstance(node.targets[0], ast.Name):
+                continue
+            chain = p_dotted_chain(node.value)
+            resolved = p_resolved_module(chain, aliases) if chain else None
+            if resolved and resolved.split(".")[0] in ALLOWED_MODULES:
+                aliases[node.targets[0].id] = resolved
+        if len(aliases) == before:
+            break
+    return aliases
+
+
+def p_dunder_warning(attr: str, prefix: str) -> Optional[str]:
+    if p_is_dunder(attr) and attr not in P_INERT_DUNDERS:
+        return f"Uses dunder '{prefix}{attr}', which walks the object graph past the allowlist"
+    return None
+
+
+def p_attribute_warning(chain: List[str], aliases: Dict[str, str]) -> Optional[str]:
+    """The verdict on one resolved attribute chain, dunders first."""
+    for attr in chain[1:]:
+        dunder = p_dunder_warning(attr, ".")
+        if dunder:
+            return dunder
+    for depth in range(2, len(chain) + 1):
+        reached = p_resolved_module(chain[:depth], aliases)
+        if reached and reached.split(".")[0] not in ALLOWED_MODULES:
+            return f"Reaches module '{reached}' via '{'.'.join(chain[:depth])}' (outside the safe-data-shaping allowlist)"
+    return None
+
+
+def p_call_warning(node: ast.Call, aliases: Dict[str, str]) -> Optional[str]:
+    if not isinstance(node.func, ast.Name):
+        return None
+    name = node.func.id
+    if name in P_BLOCKED_BUILTINS:
+        return f"Calls builtin '{name}()' which can escape the sandbox"
+    if name in P_NAMESPACE_BUILTINS:
+        return f"Calls '{name}()', which hands back the sandbox's own namespace"
+    if name not in P_DYNAMIC_ATTR_BUILTINS:
+        return None
+    attr = node.args[1] if len(node.args) > 1 else None
+    if not isinstance(attr, ast.Constant) or not isinstance(attr.value, str):
+        return f"Computes an attribute name for '{name}()', which can spell any escape as a string"
+    base = p_dotted_chain(node.args[0])
+    if base is None:
+        return p_dunder_warning(attr.value, ".")
+    return p_attribute_warning(base + [attr.value], aliases)
+
+
+def p_star_import_warning(module: str, aliases: Dict[str, str]) -> Optional[str]:
+    """`from json import *` binds whatever json's __all__ names, which is a
+    short list of functions today but is not ours to assume."""
+    try:
+        imported = importlib.import_module(module)
+    except Exception:
+        return None
+    names = getattr(imported, "__all__", None) or [n for n in dir(imported) if not n.startswith("_")]
+    for name in names:
+        warning = p_attribute_warning([module, str(name)], aliases)
+        if warning:
+            return warning
+    return None
+
+
+def get_code_warnings(code: str) -> List[str]:
+    """Return human-readable warnings for every static risk, without raising.
+
+    `/api/outputs/execute` surfaces these in the run dialog, so an Output that
+    genuinely needs `pandas` gets a "review and click Run Anyway" affordance
+    instead of a silent 500. An empty list is what buys the no-prompt auto-run
+    path, so anything that could reach past the allowlist has to land in it. A
+    syntax error is reported as a warning rather than raised, so the dialog can
+    show it next to the code.
+    """
+    try:
+        tree = ast.parse(code)
+    except SyntaxError as e:
+        return [f"Syntax error: {e}"]
+
+    aliases = p_module_aliases(tree)
+    warnings: List[str] = []
+    seen: Set[str] = set()
+
+    def note(msg: Optional[str]) -> None:
+        if msg and msg not in seen:
+            seen.add(msg)
+            warnings.append(msg)
+
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name.split(".")[0] not in ALLOWED_MODULES:
+                    note(f"Imports '{alias.name}' (outside the safe-data-shaping allowlist)")
+        elif isinstance(node, ast.ImportFrom):
+            root = (node.module or "").split(".")[0]
+            if root not in ALLOWED_MODULES:
+                note(f"Imports from '{node.module}' (outside the safe-data-shaping allowlist)")
+                continue
+            for alias in node.names:
+                if alias.name == "*":
+                    note(p_star_import_warning(root, aliases))
+                else:
+                    note(p_attribute_warning([root, alias.name], aliases))
+        elif isinstance(node, ast.Call):
+            note(p_call_warning(node, aliases))
+        elif isinstance(node, ast.Attribute):
+            chain = p_dotted_chain(node)
+            note(p_attribute_warning(chain, aliases) if chain else p_dunder_warning(node.attr, "."))
+        elif isinstance(node, ast.Name):
+            if node.id in P_SANDBOX_MODULE_HANDLES:
+                note(f"References '{node.id}', a live module the sandbox binds but the allowlist withholds")
+            else:
+                note(p_dunder_warning(node.id, ""))
+    return warnings
+
+
+def validate_code_safety(code: str) -> None:
+    """Raise UnsafeCodeError on the first static risk. The strict wrapper around
+    get_code_warnings, for callers with no user to ask."""
+    warnings = get_code_warnings(code)
+    if warnings:
+        raise UnsafeCodeError(warnings[0])

openswarm-edge/app/main.py

@@ -20,7 +20,8 @@ from .bundles import get_bundle, resolve_file
 from .fallback import apex_page, not_found_page
 from .inject import inject_runtime
 from .ratelimit import RateLimiter
-from .sandbox import UnsafeCodeError, run_backend
+from .code_safety import UnsafeCodeError
+from .sandbox import run_backend
 
 APPS_BASE_DOMAIN = os.environ.get("APPS_BASE_DOMAIN", "openswarm.host")
 # The metered-LLM call goes to the cloud over Fly's PRIVATE 6PN mesh (encrypted,

openswarm-edge/app/sandbox.py

@@ -1,13 +1,13 @@
 """Sandboxed Python runner for published apps' backend.py compute.
 
 VENDORED from backend/apps/outputs/executor.py (the desktop App Builder runtime).
-Keep the allow/deny lists + the subprocess hardening in sync with that file; this
-is the same data-shaping sandbox, just running in the edge instead of on the
-desktop. Pure compute only: no network, no disk, no subprocess, no secrets. Safe
-to run multi-tenant on one machine because nothing here can reach shared state."""
+Keep the subprocess hardening in sync with that file; this is the same
+data-shaping sandbox, just running in the edge instead of on the desktop. The
+static gate it runs on every call lives in the vendored app/code_safety.py. Pure
+compute only: no network, no disk, no subprocess, no secrets. Safe to run
+multi-tenant on one machine because nothing here can reach shared state."""
 from __future__ import annotations
 
-import ast
 import asyncio
 import json
 import os
@@ -15,46 +15,10 @@ import sys
 import tempfile
 from dataclasses import dataclass
 
+from app.code_safety import ALLOWED_MODULES, validate_code_safety
+
 TIMEOUT_SECONDS = 30
 
-_ALLOWED_MODULES = frozenset({
-    "json", "math", "re", "datetime", "collections", "itertools",
-    "functools", "statistics", "decimal", "fractions", "random",
-    "string", "textwrap", "unicodedata", "csv", "copy", "enum",
-    "dataclasses", "typing", "abc", "numbers", "uuid", "hashlib",
-    "base64", "binascii", "operator", "heapq", "bisect", "array",
-})
-
-_BLOCKED_BUILTINS = frozenset({
-    "exec", "eval", "compile", "__import__", "open", "input",
-    "breakpoint", "exit", "quit",
-})
-
-
-class UnsafeCodeError(Exception):
-    """AST validation rejected the backend code."""
-
-
-def validate_code_safety(code: str) -> None:
-    """Raise UnsafeCodeError on the first AST-visible risk. Published apps are
-    vetted at publish time, but we re-check here: the edge never trusts that the
-    bundle in storage matches what was scanned."""
-    try:
-        tree = ast.parse(code)
-    except SyntaxError as e:
-        raise UnsafeCodeError(f"Syntax error: {e}")
-    for node in ast.walk(tree):
-        if isinstance(node, ast.Import):
-            for alias in node.names:
-                if alias.name.split(".")[0] not in _ALLOWED_MODULES:
-                    raise UnsafeCodeError(f"import '{alias.name}' is not allowed")
-        elif isinstance(node, ast.ImportFrom):
-            if node.module and node.module.split(".")[0] not in _ALLOWED_MODULES:
-                raise UnsafeCodeError(f"import from '{node.module}' is not allowed")
-        elif isinstance(node, ast.Call):
-            if isinstance(node.func, ast.Name) and node.func.id in _BLOCKED_BUILTINS:
-                raise UnsafeCodeError(f"builtin '{node.func.id}()' is not allowed")
-
 
 def _minimal_env() -> dict:
     return {
@@ -79,19 +43,22 @@ async def run_backend(code: str, input_data: dict) -> ComputeResult:
 
     preamble = (
         "import json, sys, io, builtins\n"
-        "for _b in ('exec','eval','compile','open','input',\n"
-        "           'breakpoint','exit','quit'):\n"
-        "    try: delattr(builtins, _b)\n"
-        "    except AttributeError: pass\n"
-        "_orig_stdout = sys.stdout\n"
-        "_capture = io.StringIO()\n"
-        "sys.stdout = _capture\n"
+        "p_stdout = sys.stdout\n"
+        "p_capture = io.StringIO()\n"
+        "sys.stdout = p_capture\n"
         "input_data = json.loads(sys.stdin.read())\n"
         "result = {}\n"
+        # Warm the allowlist BEFORE scrubbing builtins: half the stdlib borrows the builtins the scrub deletes while it loads (tokenize does `from builtins import open`, taking `import dataclasses` with it). Then the module handles go, because leaving `sys` bound hands gate-passing code a live `sys.modules['os']` with no import statement in sight.
+        f"for p_name in {tuple(sorted(ALLOWED_MODULES))!r}:\n"
+        "    try: __import__(p_name)\n"
+        "    except ImportError: pass\n"
+        "for p_name in ('open','input','breakpoint','exit','quit'):\n"
+        "    try: delattr(builtins, p_name)\n"
+        "    except AttributeError: pass\n"
+        "del sys, io, builtins, p_name\n"
     )
     postamble = (
-        "\nsys.stdout = _orig_stdout\n"
-        'json.dump({"__stdout__": _capture.getvalue(), "__result__": result}, sys.stdout)\n'
+        "\np_stdout.write(json.dumps({\"__stdout__\": p_capture.getvalue(), \"__result__\": result}))\n"
     )
     wrapper = preamble + code + postamble
 

openswarm-edge/tests/test_edge.py

@@ -21,7 +21,9 @@ from app.main import slug_from_host
 from app.bundles import unpack, resolve_file
 from app.inject import inject_runtime
 from app.ratelimit import RateLimiter
-from app.sandbox import validate_code_safety, run_backend, UnsafeCodeError
+from app.code_safety import validate_code_safety, UnsafeCodeError
+from app import sandbox as edge_sandbox
+from app.sandbox import run_backend
 
 
 def test_slug_from_host():
@@ -179,11 +181,51 @@ def test_sandbox_rejects_unsafe_and_allows_safe():
     validate_code_safety("import math\nresult={'x': math.pi}")  # no raise
 
 
+def test_sandbox_rejects_the_module_handle_escapes():
+    """Issue #134 at the public tier: the preamble's own `sys`/`io` handles, an
+    attribute chain onto a withheld module, and the dunder walk."""
+    for code in (
+        "result = {'cwd': sys.modules['os'].getcwd()}",
+        "result = {'x': str(io.open)}",
+        "result = {'c': str(json.codecs)}",
+        "result = {'n': len(().__class__.__bases__[0].__subclasses__())}",
+        "result = {'c': str(getattr(json, 'codecs'))}",
+    ):
+        try:
+            validate_code_safety(code)
+            assert False, f"expected UnsafeCodeError for {code!r}"
+        except UnsafeCodeError:
+            pass
+
+
 def test_sandbox_runs_safe_code():
     res = asyncio.run(run_backend("result = {'sum': sum(input_data['nums'])}", {"nums": [1, 2, 3]}))
     assert res.result == {"sum": 6}
 
 
+def test_sandbox_runs_allowlisted_imports():
+    """The builtins scrub used to delete exec/eval, which broke `import statistics`
+    and every namedtuple; a sandbox that can't run real code isn't secure, it's off."""
+    res = asyncio.run(run_backend(
+        "import statistics, datetime\n"
+        "result = {'mean': statistics.mean(input_data['nums']), 'd': datetime.time(9, 0).isoformat()}",
+        {"nums": [1, 2, 3]},
+    ))
+    assert res.result == {"mean": 2, "d": "09:00:00"}
+
+
+def test_sandbox_subprocess_has_no_module_handles(monkeypatch):
+    """Second wall: pretend a payload beats the gate, and the subprocess still
+    has no module left to grab."""
+    monkeypatch.setattr(edge_sandbox, "validate_code_safety", lambda code: None)
+    for handle in ("sys", "io", "builtins"):
+        try:
+            asyncio.run(run_backend(f"result = {{'x': str({handle})}}", {}))
+            assert False, f"{handle} was still reachable"
+        except RuntimeError as e:
+            assert "NameError" in str(e)
+
+
 def test_inject_runtime():
     out = inject_runtime(b"<html><head><title>x</title></head><body>hi</body></html>").decode()
     assert "OUTPUT_COMPUTE" in out and "OUTPUT_LLM" in out