deer-flow/backend/tests/test_tool_output_budget_middleware.py
Aari 3be3969f8f
fix(agent): snap tool-output tail forward so fallback truncation respects max_chars (#4017)
* fix(agent): snap tool-output tail forward so fallback truncation respects max_chars

_snap_to_line_boundary() moves an offset backwards to the preceding newline.
That is correct for the head's end offset, but _build_fallback() also applied it
to the tail's start offset, where moving backwards lengthens the tail. On output
whose last newline sits in the second half (log lines followed by one long
unbroken line: minified JSON, base64 artifacts), the returned string exceeded
max_chars by up to 17x, defeating the guard that exists to stop a single large
tool result from blowing the model context.

Add _snap_start_to_line_boundary(), the forward-snapping mirror, and use it for
the tail offset. The existing head_end guard becomes redundant because a forward
snap can only move the tail start away from the head.

test_result_never_exceeds_max_chars already asserted this invariant but passed
newline-free content, so the snapping branch was never exercised.

* test(agent): pin the forward-snap direction of the fallback tail

The bound test only asserts that the result fits max_chars. Its content has
no newline inside the tail's snap window, so _snap_start_to_line_boundary
returns pos unchanged and the test stays green even with the snap removed.

Place a newline in the window so the snap has to fire: the tail must begin
after it, which the pre-fix backward snap does not do.
2026-07-10 08:07:25 +08:00

1302 lines
51 KiB
Python

"""Comprehensive tests for ToolOutputBudgetMiddleware.
Covers: pass-through, disk externalization, fallback truncation, UTF-8
boundaries, Command results, model-request history patching, config
variations, exempt tools, per-tool overrides, edge cases, and both
sync/async code paths.
"""
from __future__ import annotations
import os
import tempfile
from types import SimpleNamespace
import pytest
from langchain.agents.middleware.types import ModelRequest
from langchain_core.messages import AIMessage, HumanMessage, ToolMessage
from langgraph.types import Command
from deerflow.agents.middlewares.tool_output_budget_middleware import (
ToolOutputBudgetMiddleware,
_build_fallback,
_build_preview,
_effective_trigger,
_externalize,
_message_text,
_needs_budget,
_patch_model_messages,
_sanitize_tool_name,
_snap_start_to_line_boundary,
_snap_to_line_boundary,
_tool_message_over_budget,
)
from deerflow.config.app_config import AppConfig
from deerflow.config.sandbox_config import SandboxConfig
from deerflow.config.tool_output_config import ToolOutputConfig
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
def _lines_then_long_line(total: int, newline_ratio: float = 0.6) -> str:
"""Content that is line-oriented for the first *newline_ratio*, then one unbroken line.
Mirrors real bash/web_fetch output that logs progress lines and then dumps a
single-line artifact (minified JSON, base64 blob). The last newline lands in
the second half of the content, which is what exercises line snapping around
the tail offset.
"""
head_len = int(total * newline_ratio)
lines = "".join(f"[info] step {i} ok\n" for i in range(head_len // 18 + 1))[:head_len]
lines = lines[:-1] + "\n" if not lines.endswith("\n") else lines
return lines + "A" * (total - len(lines))
def _make_request(tool_name: str = "remote_executor", tool_call_id: str = "tc-1", outputs_path: str | None = None) -> SimpleNamespace:
thread_data = {"outputs_path": outputs_path} if outputs_path else None
state = {"thread_data": thread_data} if thread_data else {}
runtime = SimpleNamespace(state=state)
return SimpleNamespace(
tool_call={"name": tool_name, "id": tool_call_id},
runtime=runtime,
)
def _tm(content: str = "ok", name: str = "tool", tool_call_id: str = "tc-1") -> ToolMessage:
return ToolMessage(content=content, name=name, tool_call_id=tool_call_id)
# ===========================================================================
# Unit tests for helper functions
# ===========================================================================
class TestMessageText:
def test_string_content(self):
assert _message_text("hello") == "hello"
def test_none_content(self):
assert _message_text(None) is None
def test_list_of_strings(self):
assert _message_text(["a", "b"]) == "a\nb"
def test_list_of_text_dicts(self):
assert _message_text([{"text": "x"}, {"text": "y"}]) == "x\ny"
def test_list_with_image_returns_none(self):
assert _message_text([{"type": "image", "data": "..."}]) is None
def test_empty_list(self):
assert _message_text([]) is None
def test_non_string_non_list(self):
assert _message_text(42) is None
class TestSnapToLineBoundary:
def test_snaps_to_newline(self):
text = "line1\nline2\nline3"
pos = 14 # inside "line3"
result = _snap_to_line_boundary(text, pos)
assert text[result - 1] == "\n"
def test_no_snap_when_no_newline_in_range(self):
text = "abcdefghij"
assert _snap_to_line_boundary(text, 8) == 8
def test_zero_pos(self):
assert _snap_to_line_boundary("abc", 0) == 0
def test_pos_beyond_length(self):
assert _snap_to_line_boundary("abc", 10) == 10
class TestSnapStartToLineBoundary:
def test_snaps_forward_to_newline(self):
text = "line1\nline2\nline3"
result = _snap_start_to_line_boundary(text, 2) # inside "line1"
assert text[result - 1] == "\n"
assert result >= 2
def test_never_moves_backwards(self):
text = "aaaa\n" + "b" * 20
for pos in range(1, len(text)):
assert _snap_start_to_line_boundary(text, pos) >= pos
def test_no_snap_when_no_newline_in_range(self):
assert _snap_start_to_line_boundary("abcdefghij", 2) == 2
def test_zero_pos(self):
assert _snap_start_to_line_boundary("a\nbc", 0) == 0
def test_pos_beyond_length(self):
assert _snap_start_to_line_boundary("abc", 10) == 10
class TestExternalize:
def test_writes_file_and_returns_virtual_path(self):
with tempfile.TemporaryDirectory() as tmpdir:
path = _externalize(
"full content here",
tool_name="bash",
tool_call_id="tc-1",
outputs_path=tmpdir,
storage_subdir=".tool-results",
)
assert path is not None
assert path.startswith("/mnt/user-data/outputs/.tool-results/bash-")
assert path.endswith(".log")
# Verify actual file on disk
storage_dir = os.path.join(tmpdir, ".tool-results")
files = os.listdir(storage_dir)
assert len(files) == 1
with open(os.path.join(storage_dir, files[0]), encoding="utf-8") as f:
assert f.read() == "full content here"
def test_returns_none_on_invalid_path(self):
# ``/dev/null`` is a character device on both Linux and macOS, so
# ``os.makedirs`` cannot create any subdirectory under it for any
# user (including root). The previously-used ``/nonexistent/...``
# path was silently created by ``mkdir -p`` when the test process
# ran as root inside the CI container, which made this test fail
# in CI independently of the externalization logic under test.
path = _externalize(
"data",
tool_name="test",
tool_call_id="tc-1",
outputs_path="/dev/null/cannot-mkdir-here",
storage_subdir=".tool-results",
)
assert path is None
def test_txt_extension_for_unknown_tool(self):
with tempfile.TemporaryDirectory() as tmpdir:
path = _externalize(
"data",
tool_name="unknown_tool",
tool_call_id="tc-1",
outputs_path=tmpdir,
storage_subdir=".tool-results",
)
assert path is not None
assert path.endswith(".txt")
class TestSanitizeToolName:
def test_strips_path_separators(self):
assert _sanitize_tool_name("../../etc/passwd") == "passwd"
def test_strips_backslashes(self):
result = _sanitize_tool_name("..\\..\\windows\\system32")
assert ".." not in result
assert "/" not in result
def test_normal_name_unchanged(self):
assert _sanitize_tool_name("bash") == "bash"
def test_empty_becomes_unknown(self):
assert _sanitize_tool_name("") == "unknown"
def test_dots_only_becomes_unknown(self):
assert _sanitize_tool_name("..") == "unknown"
class TestExternalizePathTraversal:
def test_traversal_tool_name_is_sanitized(self):
with tempfile.TemporaryDirectory() as tmpdir:
path = _externalize(
"data",
tool_name="../../etc/passwd",
tool_call_id="tc-1",
outputs_path=tmpdir,
storage_subdir=".tool-results",
)
assert path is not None
assert "passwd-" in path
assert "../" not in path
def test_absolute_storage_subdir_rejected(self):
path = _externalize(
"data",
tool_name="tool",
tool_call_id="tc-1",
outputs_path="/tmp",
storage_subdir="/etc/evil",
)
assert path is None
def test_traversal_storage_subdir_rejected(self):
path = _externalize(
"data",
tool_name="tool",
tool_call_id="tc-1",
outputs_path="/tmp",
storage_subdir="../../../etc",
)
assert path is None
class TestNeedsBudget:
def test_small_output_does_not_need_budget(self):
config = ToolOutputConfig(externalize_min_chars=1000)
msg = _tm("small", name="tool")
assert _needs_budget(msg, config) is False
def test_large_output_needs_budget(self):
config = ToolOutputConfig(externalize_min_chars=50)
msg = _tm("x" * 100, name="tool")
assert _needs_budget(msg, config) is True
def test_exempt_tool_does_not_need_budget(self):
config = ToolOutputConfig(externalize_min_chars=10)
msg = _tm("x" * 100, name="read_file")
assert _needs_budget(msg, config) is False
def test_multimodal_does_not_need_budget(self):
config = ToolOutputConfig(externalize_min_chars=10)
msg = ToolMessage(content=[{"type": "image", "data": "x" * 100}], name="tool", tool_call_id="tc-1")
assert _needs_budget(msg, config) is False
class TestBuildPreview:
def test_contains_head_and_tail_and_reference(self):
content = "HEAD_" + "x" * 5000 + "_TAIL"
preview = _build_preview(
content,
tool_name="bash",
virtual_path="/mnt/test/bash-abc.log",
head_chars=100,
tail_chars=50,
)
assert preview.startswith("HEAD_")
assert "_TAIL" in preview
assert "/mnt/test/bash-abc.log" in preview
assert "read_file" in preview
assert "start_line and end_line" in preview
def test_reports_total_chars(self):
content = "a" * 10000
preview = _build_preview(
content,
tool_name="web_search",
virtual_path="/mnt/test/file.txt",
head_chars=200,
tail_chars=100,
)
assert "10000 chars" in preview
class TestBuildFallback:
def test_short_content_unchanged(self):
assert _build_fallback("short", tool_name="t", max_chars=100, head_chars=50, tail_chars=50) == "short"
def test_zero_max_disables(self):
content = "a" * 1000
assert _build_fallback(content, tool_name="t", max_chars=0, head_chars=50, tail_chars=50) == content
def test_truncates_long_content(self):
content = "H" * 5000 + "M" * 20000 + "T" * 5000
result = _build_fallback(content, tool_name="bash", max_chars=12000, head_chars=6000, tail_chars=3000)
assert len(result) < len(content)
assert "omitted from bash output" in result
assert "Persistent storage unavailable" in result
def test_preserves_head_and_tail(self):
content = "HEADSTART" + "x" * 50000 + "TAILEND"
result = _build_fallback(content, tool_name="t", max_chars=20000, head_chars=10000, tail_chars=5000)
assert result.startswith("HEADSTART")
assert "TAILEND" in result
def test_result_never_exceeds_max_chars(self):
"""The marker itself has non-zero length; total must still respect max_chars."""
for max_chars in [200, 500, 1000, 5000, 20000]:
content = "x" * 50000
result = _build_fallback(content, tool_name="long_tool_name", max_chars=max_chars, head_chars=max_chars // 2, tail_chars=max_chars // 4)
assert len(result) <= max_chars, f"max_chars={max_chars}: got {len(result)}"
def test_result_never_exceeds_max_chars_with_newlines(self):
"""Same guarantee as above, on content that actually exercises line snapping.
``test_result_never_exceeds_max_chars`` passes newline-free content, so the
tail offset is never snapped. Real bash/web_fetch output has newlines.
"""
for total in [50_000, 200_000, 1_000_000]:
content = _lines_then_long_line(total)
result = _build_fallback(content, tool_name="bash", max_chars=30_000, head_chars=8_000, tail_chars=3_000)
assert len(result) <= 30_000, f"total={total}: got {len(result)}"
def test_fallback_forward_snaps_tail_onto_line_boundary(self):
"""The tail must begin *after* the newline, never before it.
The bound test above never moves the tail offset: its content has no
newline inside the snap window, so it would pass even with the snap
removed. Placing a newline in the window pins the direction instead —
a backward snap leaves the tail starting mid-line.
"""
total, newline_pos = 100_000, 98_000 # window is [97_000, 98_500)
content = "A" * newline_pos + "\n" + "B" * (total - newline_pos - 1)
result = _build_fallback(content, tool_name="bash", max_chars=30_000, head_chars=8_000, tail_chars=3_000)
assert len(result) <= 30_000
tail = result.rsplit("]\n\n", 1)[1]
assert tail.startswith("B"), f"tail begins mid-line: {tail[:20]!r}"
def test_very_small_max_chars_does_not_crash(self):
content = "x" * 1000
result = _build_fallback(content, tool_name="t", max_chars=50, head_chars=20, tail_chars=10)
assert len(result) <= 50
# ===========================================================================
# Middleware integration tests — wrap_tool_call
# ===========================================================================
class TestWrapToolCallPassThrough:
def test_small_output_passes_through(self):
mw = ToolOutputBudgetMiddleware(config=ToolOutputConfig(externalize_min_chars=1000))
msg = _tm("small output", name="bash")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
def test_disabled_middleware_passes_through(self):
mw = ToolOutputBudgetMiddleware(config=ToolOutputConfig(enabled=False, externalize_min_chars=10, fallback_max_chars=20))
msg = _tm("x" * 50000, name="bash")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
class TestWrapToolCallExternalize:
def test_oversized_output_externalized_to_disk(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=100, preview_head_chars=50, preview_tail_chars=30)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="remote_executor")
req = _make_request(outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
assert result is not msg
assert "Full remote_executor output saved to" in result.content
assert "read_file" in result.content
assert result.tool_call_id == "tc-1"
# Verify file was written
storage_dir = os.path.join(tmpdir, ".tool-results")
assert os.path.isdir(storage_dir)
files = os.listdir(storage_dir)
assert len(files) == 1
with open(os.path.join(storage_dir, files[0]), encoding="utf-8") as f:
assert f.read() == content
def test_preview_contains_head_and_tail(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = "HEADPART_" + "m" * 200 + "_TAILPART"
msg = _tm(content, name="web_search")
req = _make_request(outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert result.content.startswith("HEADPART_")
assert "_TAILPART" in result.content
class TestWrapToolCallFallback:
def test_fallback_when_no_outputs_path(self):
config = ToolOutputConfig(
externalize_min_chars=50,
fallback_max_chars=200,
fallback_head_chars=80,
fallback_tail_chars=40,
)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="mcp_tool")
req = _make_request(outputs_path=None)
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
assert result is not msg
assert "omitted from mcp_tool output" in result.content
assert "Persistent storage unavailable" in result.content
assert len(result.content) < len(content)
def test_fallback_when_disk_write_fails(self):
config = ToolOutputConfig(
externalize_min_chars=50,
fallback_max_chars=200,
fallback_head_chars=80,
fallback_tail_chars=40,
)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="tool")
req = _make_request(outputs_path="/dev/null/cannot-mkdir-here")
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
assert "omitted from tool output" in result.content
class TestWrapToolCallExemption:
def test_read_file_exempt(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 100
msg = _tm(content, name="read_file")
result = mw.wrap_tool_call(_make_request(tool_name="read_file"), lambda _: msg)
assert result is msg
def test_read_file_tool_exempt(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 100
msg = _tm(content, name="read_file_tool")
result = mw.wrap_tool_call(_make_request(tool_name="read_file_tool"), lambda _: msg)
assert result is msg
def test_custom_exempt_tool(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=50, exempt_tools=["my_tool"])
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 100
msg = _tm(content, name="my_tool")
result = mw.wrap_tool_call(_make_request(tool_name="my_tool"), lambda _: msg)
assert result is msg
class TestWrapToolCallPerToolOverride:
def test_per_tool_threshold(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(
externalize_min_chars=50000, # global: high
tool_overrides={"sensitive_tool": 100}, # override: low
)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="sensitive_tool")
req = _make_request(tool_name="sensitive_tool", outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is not msg
assert "Full sensitive_tool output saved to" in result.content
def test_per_tool_zero_disables_externalization(self):
config = ToolOutputConfig(
externalize_min_chars=50,
tool_overrides={"bash": 0},
fallback_max_chars=200,
fallback_head_chars=80,
fallback_tail_chars=40,
)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="bash")
# Even with outputs_path, externalization disabled for bash
req = _make_request(tool_name="bash", outputs_path="/tmp/test")
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
# Should use fallback instead of externalization
assert "Persistent storage unavailable" in result.content or "omitted" in result.content
class TestWrapToolCallCommand:
def test_command_messages_are_patched(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
tool_msg = _tm("x" * 200, name="present_files")
command = Command(update={"messages": [tool_msg], "artifacts": ["/mnt/report.html"]})
req = _make_request(tool_name="present_files", outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: command)
assert isinstance(result, Command)
assert result is not command
assert result.update["artifacts"] == ["/mnt/report.html"]
new_msg = result.update["messages"][0]
assert isinstance(new_msg, ToolMessage)
assert "Full present_files output saved to" in new_msg.content
def test_command_without_messages_unchanged(self):
config = ToolOutputConfig(externalize_min_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
command = Command(update={"key": "value"})
result = mw.wrap_tool_call(_make_request(), lambda _: command)
assert result is command
class TestWrapToolCallEdgeCases:
def test_none_content_passes_through(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=20)
mw = ToolOutputBudgetMiddleware(config=config)
msg = ToolMessage(content=None, name="tool", tool_call_id="tc-1")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
def test_empty_string_passes_through(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=20)
mw = ToolOutputBudgetMiddleware(config=config)
msg = _tm("", name="tool")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
def test_multimodal_content_skipped(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=20)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "image", "data": "x" * 100}]
msg = ToolMessage(content=content, name="tool", tool_call_id="tc-1")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
def test_exactly_at_threshold_passes_through(self):
config = ToolOutputConfig(externalize_min_chars=100, fallback_max_chars=100)
mw = ToolOutputBudgetMiddleware(config=config)
msg = _tm("x" * 100, name="tool")
result = mw.wrap_tool_call(_make_request(), lambda _: msg)
assert result is msg
def test_one_char_over_threshold_triggers(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=100)
mw = ToolOutputBudgetMiddleware(config=config)
msg = _tm("x" * 101, name="tool")
req = _make_request(outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is not msg
def test_chinese_content_preserved(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = "你好世界" * 50
msg = _tm(content, name="tool")
req = _make_request(outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
# File should contain the full Chinese content
storage_dir = os.path.join(tmpdir, ".tool-results")
files = os.listdir(storage_dir)
with open(os.path.join(storage_dir, files[0]), encoding="utf-8") as f:
assert f.read() == content
def test_no_runtime_state_uses_fallback(self):
config = ToolOutputConfig(
externalize_min_chars=50,
fallback_max_chars=500,
fallback_head_chars=100,
fallback_tail_chars=50,
)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 1000
msg = _tm(content, name="tool")
req = SimpleNamespace(
tool_call={"name": "tool", "id": "tc-1"},
runtime=None,
)
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
assert "omitted" in result.content
assert len(result.content) <= 500
# ===========================================================================
# MCP content_and_artifact format tests
# ===========================================================================
class TestMCPContentAndArtifact:
"""MCP tools return content as list of content blocks, not plain strings."""
def test_text_content_blocks_are_budgeted(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "text", "text": "x" * 200}]
msg = ToolMessage(content=content, name="mcp_tool", tool_call_id="tc-mcp")
req = _make_request(tool_name="mcp_tool", outputs_path=tmpdir)
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is not msg
assert isinstance(result.content, str)
assert "Full mcp_tool output saved to" in result.content
assert result.tool_call_id == "tc-mcp"
def test_multiple_text_blocks_joined_and_budgeted(self):
config = ToolOutputConfig(externalize_min_chars=50, fallback_max_chars=500, fallback_head_chars=100, fallback_tail_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "text", "text": "a" * 300}, {"type": "text", "text": "b" * 300}]
msg = ToolMessage(content=content, name="mcp_tool", tool_call_id="tc-mcp2")
req = _make_request(tool_name="mcp_tool")
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is not msg
assert "omitted" in result.content
def test_image_content_blocks_are_skipped(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=20)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "image", "data": "base64data" * 100}]
msg = ToolMessage(content=content, name="mcp_tool", tool_call_id="tc-img")
req = _make_request(tool_name="mcp_tool")
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is msg
def test_mixed_text_and_image_blocks_are_skipped(self):
config = ToolOutputConfig(externalize_min_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "text", "text": "x" * 100}, {"type": "image", "data": "base64"}]
msg = ToolMessage(content=content, name="mcp_tool", tool_call_id="tc-mix")
req = _make_request(tool_name="mcp_tool")
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is msg
def test_small_text_blocks_pass_through(self):
config = ToolOutputConfig(externalize_min_chars=1000)
mw = ToolOutputBudgetMiddleware(config=config)
content = [{"type": "text", "text": "small result"}]
msg = ToolMessage(content=content, name="mcp_tool", tool_call_id="tc-sm")
req = _make_request(tool_name="mcp_tool")
result = mw.wrap_tool_call(req, lambda _: msg)
assert result is msg
# ===========================================================================
# Async path tests
# ===========================================================================
class TestAsyncPaths:
@pytest.mark.anyio
async def test_async_tool_call_externalized(self):
with tempfile.TemporaryDirectory() as tmpdir:
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 200
msg = _tm(content, name="async_tool")
req = _make_request(tool_name="async_tool", outputs_path=tmpdir)
async def handler(_):
return msg
result = await mw.awrap_tool_call(req, handler)
assert isinstance(result, ToolMessage)
assert result is not msg
assert "Full async_tool output saved to" in result.content
@pytest.mark.anyio
async def test_async_model_call_patches_history(self):
config = ToolOutputConfig(fallback_max_chars=500, fallback_head_chars=100, fallback_tail_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
oversized = _tm("h" * 1000, name="tool", tool_call_id="tc-h")
request = ModelRequest(model=None, messages=[oversized], tools=[], state={})
captured: dict[str, ModelRequest] = {}
async def handler(req):
captured["request"] = req
return []
await mw.awrap_model_call(request, handler)
forwarded = captured["request"]
assert forwarded is not request
msg = forwarded.messages[0]
assert isinstance(msg, ToolMessage)
assert "omitted" in msg.content
# ===========================================================================
# wrap_model_call — historical message patching
# ===========================================================================
class TestWrapModelCall:
def test_oversized_historical_messages_truncated(self):
config = ToolOutputConfig(fallback_max_chars=500, fallback_head_chars=100, fallback_tail_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
oversized = _tm("q" * 1000, name="tool", tool_call_id="tc-q")
request = ModelRequest(model=None, messages=[oversized], tools=[], state={})
captured: dict[str, ModelRequest] = {}
def handler(req):
captured["request"] = req
return []
mw.wrap_model_call(request, handler)
forwarded = captured["request"]
assert forwarded is not request
msg = forwarded.messages[0]
assert isinstance(msg, ToolMessage)
assert "omitted" in msg.content
assert len(msg.content) < len(oversized.content) + 150
def test_small_historical_messages_unchanged(self):
config = ToolOutputConfig(fallback_max_chars=1000)
mw = ToolOutputBudgetMiddleware(config=config)
small = _tm("small", name="tool")
request = ModelRequest(model=None, messages=[small], tools=[], state={})
captured: dict[str, ModelRequest] = {}
def handler(req):
captured["request"] = req
return []
mw.wrap_model_call(request, handler)
assert captured["request"] is request
def test_exempt_tools_in_history_unchanged(self):
config = ToolOutputConfig(fallback_max_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
read_msg = _tm("x" * 200, name="read_file", tool_call_id="tc-r")
request = ModelRequest(model=None, messages=[read_msg], tools=[], state={})
captured: dict[str, ModelRequest] = {}
def handler(req):
captured["request"] = req
return []
mw.wrap_model_call(request, handler)
assert captured["request"] is request
def test_non_tool_messages_preserved(self):
config = ToolOutputConfig(fallback_max_chars=500, fallback_head_chars=100, fallback_tail_chars=50)
mw = ToolOutputBudgetMiddleware(config=config)
human = HumanMessage(content="x" * 200)
ai = AIMessage(content="y" * 200)
oversized_tool = _tm("z" * 1000, name="tool")
request = ModelRequest(model=None, messages=[human, ai, oversized_tool], tools=[], state={})
captured: dict[str, ModelRequest] = {}
def handler(req):
captured["request"] = req
return []
mw.wrap_model_call(request, handler)
msgs = captured["request"].messages
assert msgs[0] is human
assert msgs[1] is ai
assert isinstance(msgs[2], ToolMessage)
assert "omitted" in msgs[2].content
# ===========================================================================
# Config integration
# ===========================================================================
class TestFromAppConfig:
def test_from_app_config_with_tool_output(self):
config = AppConfig(
sandbox=SandboxConfig(use="test"),
tool_output={"externalize_min_chars": 5000, "preview_head_chars": 500},
)
mw = ToolOutputBudgetMiddleware.from_app_config(config)
assert mw._config.externalize_min_chars == 5000
assert mw._config.preview_head_chars == 500
def test_from_app_config_defaults(self):
config = AppConfig(sandbox=SandboxConfig(use="test"))
mw = ToolOutputBudgetMiddleware.from_app_config(config)
assert mw._config.externalize_min_chars == 12000
class TestPatchModelMessages:
def test_returns_none_when_no_changes(self):
config = ToolOutputConfig(fallback_max_chars=1000)
messages = [_tm("short", name="tool")]
assert _patch_model_messages(messages, config) is None
def test_patches_oversized_messages(self):
config = ToolOutputConfig(fallback_max_chars=500, fallback_head_chars=100, fallback_tail_chars=50)
messages = [_tm("x" * 1000, name="tool")]
result = _patch_model_messages(messages, config)
assert result is not None
assert len(result) == 1
assert "omitted" in result[0].content
# ===========================================================================
# Pre-scan helpers (_effective_trigger / _tool_message_over_budget / _needs_budget)
# These guard the fast-path optimization — a false negative here is a real bug
# (budgeting silently skipped), so per-tool overrides must be honored.
# ===========================================================================
class TestPreScanHelpers:
def test_effective_trigger_uses_global_externalize(self):
config = ToolOutputConfig(externalize_min_chars=12000, fallback_max_chars=30000)
# smallest of the two thresholds wins
assert _effective_trigger("any_tool", config) == 12000
def test_effective_trigger_respects_per_tool_override(self):
config = ToolOutputConfig(externalize_min_chars=50000, fallback_max_chars=0, tool_overrides={"sensitive": 100})
assert _effective_trigger("sensitive", config) == 100
# other tools fall back to the (high) global
assert _effective_trigger("other", config) == 50000
def test_effective_trigger_per_tool_zero_falls_to_fallback(self):
config = ToolOutputConfig(externalize_min_chars=50, tool_overrides={"bash": 0}, fallback_max_chars=200)
# externalize disabled for bash → only fallback can trigger
assert _effective_trigger("bash", config) == 200
def test_effective_trigger_returns_negative_when_fully_disabled(self):
config = ToolOutputConfig(externalize_min_chars=0, fallback_max_chars=0)
assert _effective_trigger("any", config) == -1
def test_pre_scan_does_not_short_circuit_per_tool_override(self):
"""Regression: pre-scan must honor per-tool overrides, not just global threshold."""
config = ToolOutputConfig(externalize_min_chars=50000, fallback_max_chars=0, tool_overrides={"sensitive": 100})
msg = _tm("x" * 500, name="sensitive")
# 500 < global 50000 but > per-tool 100 → must still be flagged
assert _tool_message_over_budget(msg, config) is True
assert _needs_budget(msg, config) is True
def test_exempt_tool_never_over_budget(self):
config = ToolOutputConfig(externalize_min_chars=10, fallback_max_chars=20, exempt_tools=["read_file"])
msg = _tm("x" * 1000, name="read_file")
assert _tool_message_over_budget(msg, config) is False
def test_model_call_pre_scan_skips_when_nothing_oversized(self):
"""_patch_model_messages returns None (no list rebuild) when all messages are small."""
config = ToolOutputConfig(externalize_min_chars=12000, fallback_max_chars=30000)
messages = [_tm("small", name="tool"), HumanMessage(content="hi"), _tm("also small", name="bash")]
assert _patch_model_messages(messages, config) is None
# ===========================================================================
# Middleware ordering in the chain
# ===========================================================================
class TestMiddlewareChainIntegration:
def test_budget_middleware_is_first_in_chain(self):
from deerflow.agents.middlewares.tool_error_handling_middleware import build_subagent_runtime_middlewares
app_config = AppConfig(sandbox=SandboxConfig(use="test"))
middlewares = build_subagent_runtime_middlewares(app_config=app_config, lazy_init=False)
# InputSanitizationMiddleware is the outermost wrap_model_call wrapper;
# ToolOutputBudgetMiddleware is the first wrap_tool_call handler.
from deerflow.agents.middlewares.input_sanitization_middleware import InputSanitizationMiddleware
assert isinstance(middlewares[0], InputSanitizationMiddleware)
assert isinstance(middlewares[1], ToolOutputBudgetMiddleware)
def test_budget_middleware_in_lead_chain(self):
from deerflow.agents.middlewares.tool_error_handling_middleware import build_lead_runtime_middlewares
app_config = AppConfig(sandbox=SandboxConfig(use="test"))
middlewares = build_lead_runtime_middlewares(app_config=app_config, lazy_init=False)
from deerflow.agents.middlewares.input_sanitization_middleware import InputSanitizationMiddleware
assert isinstance(middlewares[0], InputSanitizationMiddleware)
assert isinstance(middlewares[1], ToolOutputBudgetMiddleware)
# ===========================================================================
# Config version bump
# ===========================================================================
class TestConfigVersion:
def test_config_version_bumped(self):
import yaml
example_path = os.path.join(os.path.dirname(__file__), "..", "..", "config.example.yaml")
if os.path.exists(example_path):
with open(example_path, encoding="utf-8") as f:
data = yaml.safe_load(f)
assert data.get("config_version", 0) >= 11
def test_config_example_has_tool_output_section(self):
import yaml
example_path = os.path.join(os.path.dirname(__file__), "..", "..", "config.example.yaml")
if os.path.exists(example_path):
with open(example_path, encoding="utf-8") as f:
data = yaml.safe_load(f)
assert "tool_output" in data
tool_output = data["tool_output"]
assert tool_output["enabled"] is True
assert tool_output["externalize_min_chars"] == 12000
assert "read_file" in tool_output["exempt_tools"]
# ===========================================================================
# externalize into sandbox for non-mounted (remote) sandboxes
# ===========================================================================
class _FakeSandbox:
"""In-memory stand-in for a Sandbox. Records calls and supports failure injection."""
def __init__(self, *, write_ok: bool = True, check_result: str = "OK") -> None:
self.commands: list[str] = []
self.writes: list[tuple[str, str]] = []
self._write_ok = write_ok
self._check_result = check_result
def execute_command(
self,
command: str,
env: dict[str, str] | None = None,
timeout: float | None = None,
) -> str:
del env, timeout
self.commands.append(command)
if command.startswith("test -s"):
return self._check_result
return ""
def write_file(self, path: str, content: str, append: bool = False) -> None:
if not self._write_ok:
raise RuntimeError("simulated write failure")
self.writes.append((path, content))
class _FakeProvider:
"""Minimal SandboxProvider stand-in for monkeypatching get_sandbox_provider."""
def __init__(self, *, uses_thread_data_mounts: bool, sandbox: _FakeSandbox | None = None) -> None:
self.uses_thread_data_mounts = uses_thread_data_mounts
self._sandbox = sandbox
def get(self, sandbox_id: str):
return self._sandbox
class TestExternalizeToSandbox:
def test_writes_and_returns_virtual_path(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import (
_externalize_to_sandbox,
)
sb = _FakeSandbox()
result = _externalize_to_sandbox(
"x" * 100,
tool_name="bash",
tool_call_id="tc-1",
storage_subdir=".tool-results",
sandbox=sb,
)
assert result is not None
assert result.startswith("/mnt/user-data/outputs/.tool-results/bash-")
assert result.endswith(".log")
assert any(c.startswith("mkdir -p ") for c in sb.commands)
assert any(c.startswith("test -s ") for c in sb.commands)
assert sb.writes and sb.writes[0][0] == result
assert sb.writes[0][1] == "x" * 100
def test_returns_none_when_write_raises(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import (
_externalize_to_sandbox,
)
result = _externalize_to_sandbox(
"x" * 100,
tool_name="web_fetch",
tool_call_id="tc-2",
storage_subdir=".tool-results",
sandbox=_FakeSandbox(write_ok=False),
)
assert result is None
def test_returns_none_when_validation_fails(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import (
_externalize_to_sandbox,
)
result = _externalize_to_sandbox(
"x" * 100,
tool_name="bash",
tool_call_id="tc-3",
storage_subdir=".tool-results",
sandbox=_FakeSandbox(check_result="MISSING"),
)
assert result is None
def test_rejects_unsafe_storage_subdir(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import (
_externalize_to_sandbox,
)
sb = _FakeSandbox()
assert (
_externalize_to_sandbox(
"x" * 100,
tool_name="bash",
tool_call_id="tc-4",
storage_subdir="../escape",
sandbox=sb,
)
is None
)
assert (
_externalize_to_sandbox(
"x" * 100,
tool_name="bash",
tool_call_id="tc-5",
storage_subdir="/abs/path",
sandbox=sb,
)
is None
)
# Sandbox must not be touched when the subdir is rejected up-front.
assert sb.commands == []
assert sb.writes == []
def test_default_extension_for_unknown_tool(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import (
_externalize_to_sandbox,
)
result = _externalize_to_sandbox(
"data",
tool_name="unknown_tool",
tool_call_id="tc-6",
storage_subdir=".tool-results",
sandbox=_FakeSandbox(),
)
assert result is not None and result.endswith(".txt")
class TestBudgetContentSandboxDispatch:
"""_budget_content must branch on uses_thread_data_mounts (issue #3416)."""
def test_mounted_sandbox_uses_host_disk(self, monkeypatch, tmp_path):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
sb = _FakeSandbox()
monkeypatch.setattr(
mod,
"get_sandbox_provider",
lambda: _FakeProvider(uses_thread_data_mounts=True, sandbox=sb),
)
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
result = mod._budget_content(
"x" * 500,
tool_name="remote_executor",
tool_call_id="tc-m",
outputs_path=str(tmp_path),
config=config,
sandbox=sb,
)
assert result is not None
assert "Full remote_executor output saved to /mnt/user-data/outputs/" in result
# Mounted path must NOT touch the sandbox.
assert sb.commands == []
assert sb.writes == []
# And the host file must exist.
storage_dir = tmp_path / ".tool-results"
assert storage_dir.is_dir()
assert len(list(storage_dir.iterdir())) == 1
def test_non_mounted_sandbox_writes_to_sandbox(self, monkeypatch, tmp_path):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
sb = _FakeSandbox()
monkeypatch.setattr(
mod,
"get_sandbox_provider",
lambda: _FakeProvider(uses_thread_data_mounts=False, sandbox=sb),
)
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
result = mod._budget_content(
"x" * 500,
tool_name="remote_executor",
tool_call_id="tc-n",
outputs_path=str(tmp_path), # present, but ignored on non-mounted path
config=config,
sandbox=sb,
)
assert result is not None
assert "Full remote_executor output saved to /mnt/user-data/outputs/" in result
# Non-mounted path MUST write into the sandbox.
assert sb.writes and sb.writes[0][1] == "x" * 500
# And MUST NOT touch the host.
assert not (tmp_path / ".tool-results").exists()
def test_non_mounted_without_sandbox_falls_back(self, monkeypatch):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
monkeypatch.setattr(
mod,
"get_sandbox_provider",
lambda: _FakeProvider(uses_thread_data_mounts=False, sandbox=None),
)
config = ToolOutputConfig(
externalize_min_chars=50,
fallback_max_chars=500,
fallback_head_chars=100,
fallback_tail_chars=50,
)
result = mod._budget_content(
"x" * 5000,
tool_name="web_search",
tool_call_id="tc-fb",
outputs_path=None,
config=config,
sandbox=None,
)
assert result is not None
assert "Persistent storage unavailable" in result
class TestResolveSandbox:
def test_returns_none_when_no_state(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import _resolve_sandbox
req = SimpleNamespace(runtime=None)
assert _resolve_sandbox(req) is None
def test_returns_none_when_state_has_no_sandbox(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import _resolve_sandbox
req = SimpleNamespace(runtime=SimpleNamespace(state={}))
assert _resolve_sandbox(req) is None
def test_returns_none_when_sandbox_id_missing(self):
from deerflow.agents.middlewares.tool_output_budget_middleware import _resolve_sandbox
req = SimpleNamespace(runtime=SimpleNamespace(state={"sandbox": {}}))
assert _resolve_sandbox(req) is None
def test_returns_sandbox_from_provider(self, monkeypatch):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
sb = _FakeSandbox()
monkeypatch.setattr(
mod,
"get_sandbox_provider",
lambda: _FakeProvider(uses_thread_data_mounts=False, sandbox=sb),
)
req = SimpleNamespace(runtime=SimpleNamespace(state={"sandbox": {"sandbox_id": "sb-1"}}))
assert mod._resolve_sandbox(req) is sb
def test_returns_none_on_provider_exception(self, monkeypatch):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
class _Boom:
def get(self, sandbox_id):
raise RuntimeError("boom")
monkeypatch.setattr(mod, "get_sandbox_provider", lambda: _Boom())
req = SimpleNamespace(runtime=SimpleNamespace(state={"sandbox": {"sandbox_id": "sb-x"}}))
assert mod._resolve_sandbox(req) is None
class TestWrapToolCallSandboxIntegration:
"""End-to-end via wrap_tool_call for the non-mounted path (issue #3416)."""
def test_oversized_output_lands_in_sandbox_not_host(self, monkeypatch, tmp_path):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
sb = _FakeSandbox()
monkeypatch.setattr(
mod,
"get_sandbox_provider",
lambda: _FakeProvider(uses_thread_data_mounts=False, sandbox=sb),
)
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
mw = ToolOutputBudgetMiddleware(config=config)
content = "x" * 500
msg = _tm(content, name="remote_executor")
# Request carries BOTH outputs_path (host) AND a sandbox_id; the
# non-mounted branch must ignore outputs_path and write into sandbox.
req = SimpleNamespace(
tool_call={"name": "remote_executor", "id": "tc-1"},
runtime=SimpleNamespace(
state={
"thread_data": {"outputs_path": str(tmp_path)},
"sandbox": {"sandbox_id": "sb-1"},
}
),
)
result = mw.wrap_tool_call(req, lambda _: msg)
assert isinstance(result, ToolMessage)
assert "Full remote_executor output saved to /mnt/user-data/outputs/" in result.content
assert sb.writes and sb.writes[0][1] == content
# Host disk must not have been written.
assert not (tmp_path / ".tool-results").exists()
class TestBudgetContentNoSandboxNoProviderCall:
"""Without a sandbox, _budget_content must NOT call get_sandbox_provider.
This is the legacy host-disk path (and the CI-without-config.yaml path):
touching the provider would raise and force inline fallback, regressing
issue #3416's fix and breaking environments that never opt into sandbox.
"""
def test_no_provider_call_when_sandbox_absent(self, monkeypatch, tmp_path):
from deerflow.agents.middlewares import tool_output_budget_middleware as mod
called = {"n": 0}
def boom():
called["n"] += 1
raise RuntimeError("provider must not be called on the legacy path")
monkeypatch.setattr(mod, "get_sandbox_provider", boom)
config = ToolOutputConfig(externalize_min_chars=50, preview_head_chars=20, preview_tail_chars=10)
result = mod._budget_content(
"x" * 500,
tool_name="remote_executor",
tool_call_id="tc-legacy",
outputs_path=str(tmp_path),
config=config,
sandbox=None,
)
assert result is not None
assert "Full remote_executor output saved to /mnt/user-data/outputs/" in result
assert called["n"] == 0
assert (tmp_path / ".tool-results").is_dir()