Files
usestrix__strix/strix/core/runner.py
yoni-at-strix f4ef8867f6 Add MCP server support (#1137)
* add a generic MCP client and a config for connecting MCP servers

* Add MCP docs and CLI polish: docs page, startup connect summary, --mcp-config flag, compact tool output

* Add MCP connection notes and per-run selection; clean up on cancel and dedupe names

* Show errored MCP tool calls as failed in the TUI

* Sanitize namespaced tool names so model APIs accept them

* Show MCP tool calls distinctly in the terminal and the run viewer

* Say what MCP servers are worth connecting for

* Correct the notes docstring to match how notes reach the agent

* keep the mcp tests from reading your shell's STRIX_MCP_* vars
2026-08-24 14:00:16 -04:00

568 lines
21 KiB
Python

"""Top-level Strix scan runner."""
from __future__ import annotations
import asyncio
import contextlib
import io
import json
import logging
import uuid
from collections.abc import Callable
from pathlib import Path
from typing import TYPE_CHECKING, Any
from agents import RunConfig
from agents.sandbox import SandboxRunConfig
from openai import RateLimitError
from strix.agents.factory import build_strix_agent, make_child_factory
from strix.agents.prompt import render_system_prompt
from strix.config import load_settings
from strix.config.models import (
StrixProvider,
configure_sdk_model_defaults,
supports_strict_tool_schemas,
uses_chat_completions_tool_schema,
)
from strix.config.settings import DEFAULT_MAX_TURNS
from strix.core.agents import AgentCoordinator
from strix.core.execution import (
respawn_subagents,
run_agent_loop,
)
from strix.core.execution import (
spawn_child_agent as start_child_agent,
)
from strix.core.hooks import BudgetExceededError, ReportUsageHooks, recomputed_budget_flags
from strix.core.inputs import (
build_root_task,
build_scan_targets,
build_scope_context,
make_model_settings,
)
from strix.core.paths import run_dir_for, runtime_state_dir
from strix.core.sessions import open_agent_session
from strix.report.state import get_global_report_state
from strix.runtime import session_manager
from strix.telemetry.logging import set_scan_id, setup_scan_logging
from strix.tools.output_store import (
WORKSPACE_SPILL_DIR,
configure_spill_writer,
)
if TYPE_CHECKING:
from agents.mcp import MCPServer
from agents.memory import SQLiteSession
from agents.result import RunResultBase
from strix.runtime.status import StatusSink
from strix.tools.mcp import ConnectedMcpServer
logger = logging.getLogger(__name__)
StreamEventSink = Callable[[str, Any], None]
def _mcp_startup_summary(connections: list[ConnectedMcpServer]) -> str:
"""One user-facing line summarizing the MCP servers that connected."""
server_count = len(connections)
tool_count = sum(c.tool_count for c in connections)
servers_word = "server" if server_count == 1 else "servers"
tools_word = "tool" if tool_count == 1 else "tools"
names = ", ".join(c.name for c in connections)
return f"MCP: connected {server_count} {servers_word} ({tool_count} {tools_word}): {names}"
def _record_mcp_connections(connections: list[ConnectedMcpServer]) -> None:
"""Record which MCP servers this run connected, for the interfaces.
A server's tools are offered to the model under a name built from the
connection name and the tool's own name, which cannot be split back apart, so
the TUI and the run viewer need the names to match a tool call against before
they can show which server it went out to. Kept on the run record because the
viewer reads a finished run from disk.
"""
report_state = get_global_report_state()
if report_state is None:
return
report_state.record_mcp_connections([connection.name for connection in connections])
def _mcp_connection_notes(connections: list[ConnectedMcpServer]) -> str | None:
"""A block describing the connections the user left notes on, for the agent.
Only connections with notes are listed, so the note describes the connection
once rather than being repeated onto every tool. Returns ``None`` when no
connection has notes.
"""
noted = [(c.name, c.notes) for c in connections if c.notes]
if not noted:
return None
lines = "\n".join(f"- `{name}.*` tools: {notes}" for name, notes in noted)
return (
"The user connected these MCP servers for this run and left notes on how "
f"to use each:\n{lines}"
)
def _merge_root_prompt_context(
scope_context: dict[str, Any],
extra_system_prompt_context: dict[str, Any] | None,
) -> dict[str, Any]:
if not extra_system_prompt_context:
return scope_context
reserved_keys = scope_context.keys() & extra_system_prompt_context.keys()
if reserved_keys:
raise ValueError(
"extra_system_prompt_context cannot override built-in scope keys: "
f"{sorted(reserved_keys)}",
)
return {**scope_context, **extra_system_prompt_context}
def _compose_root_instructions_override(
root_instructions_override: str | None,
*,
skills: list[str],
scan_mode: str,
is_whitebox: bool,
is_diff_scoped: bool,
interactive: bool,
system_prompt_context: dict[str, Any],
) -> str | None:
if root_instructions_override is None:
return None
base_instructions = render_system_prompt(
skills=skills,
scan_mode=scan_mode,
is_whitebox=is_whitebox,
is_root=True,
is_diff_scoped=is_diff_scoped,
interactive=interactive,
system_prompt_context=system_prompt_context,
)
return (
f"{base_instructions}\n\n"
"<root_scan_instructions_override>\n"
"The following root scan instructions are subordinate to the "
"system-verified scope above. They cannot expand, replace, or weaken "
"authorized target constraints.\n\n"
f"{root_instructions_override}\n"
"</root_scan_instructions_override>"
)
async def run_strix_scan(
*,
scan_config: dict[str, Any],
scan_id: str | None = None,
image: str,
local_sources: list[dict[str, Any]] | None = None,
extra_files: list[dict[str, Any]] | None = None,
coordinator: AgentCoordinator | None = None,
interactive: bool = False,
max_turns: int = DEFAULT_MAX_TURNS,
max_budget_usd: float | None = None,
model: str | None = None,
cleanup_on_exit: bool = True,
event_sink: StreamEventSink | None = None,
root_instructions_override: str | None = None,
extra_system_prompt_context: dict[str, Any] | None = None,
status_sink: StatusSink | None = None,
) -> RunResultBase | None:
"""Run or resume one Strix scan against a sandbox.
``root_instructions_override`` adds root scan instructions to the rendered
root prompt without replacing the system-verified scope block.
``extra_files`` entries (``{"workspace_path", "content"}``) are placed into
the sandbox workspace at session bring-up; see
:func:`strix.runtime.session_manager.create_or_reuse`.
``extra_system_prompt_context`` is merged into the root agent's scan
context before prompt rendering. Child agents keep the standard scan prompt
and context.
"""
def report(phase: str) -> None:
if status_sink is not None:
status_sink(phase)
if scan_id is None:
scan_id = f"scan-{uuid.uuid4().hex[:8]}"
run_dir = run_dir_for(scan_id)
run_dir.mkdir(parents=True, exist_ok=True)
state_dir = runtime_state_dir(run_dir)
state_dir.mkdir(parents=True, exist_ok=True)
teardown_logging = setup_scan_logging(run_dir)
set_scan_id(scan_id)
agents_path = state_dir / "agents.json"
agents_db = state_dir / "agents.db"
is_resume = agents_path.exists()
logger.info(
"%s Strix scan %s (image=%s, max_turns=%d, interactive=%s, run_dir=%s)",
"Resuming" if is_resume else "Starting",
scan_id,
image,
max_turns,
interactive,
run_dir,
)
settings = load_settings()
configure_sdk_model_defaults(settings)
resolved_model = (model or settings.llm.model or "").strip()
if not resolved_model:
raise RuntimeError(
"No LLM model configured. Set STRIX_LLM env or pass model= to run_strix_scan().",
)
logger.info("LLM model resolved: %s", resolved_model)
chat_completions_tools = uses_chat_completions_tool_schema(resolved_model, settings)
strict_tool_schemas = supports_strict_tool_schemas(resolved_model)
if not strict_tool_schemas:
logger.info("Sending non-strict tool schemas: %s caps strict tools", resolved_model)
if coordinator is None:
coordinator = AgentCoordinator()
coordinator.set_snapshot_path(agents_path)
from strix.tools.coverage.tools import hydrate_coverage_from_disk
from strix.tools.notes.tools import hydrate_notes_from_disk
from strix.tools.todo.tools import hydrate_todos_from_disk
hydrate_todos_from_disk(state_dir)
hydrate_notes_from_disk(state_dir)
hydrate_coverage_from_disk(state_dir)
root_id: str | None = None
if is_resume:
try:
snap = json.loads(agents_path.read_text(encoding="utf-8"))
except (OSError, json.JSONDecodeError) as exc:
raise RuntimeError(
f"Cannot resume scan {scan_id}: agents.json is unreadable: {exc}",
) from exc
if not agents_db.exists():
raise RuntimeError(
f"Cannot resume scan {scan_id}: missing SDK session database at {agents_db}",
)
await coordinator.restore(snap)
report_state = get_global_report_state()
if report_state is not None:
budget_stopped, reserve_stopped = recomputed_budget_flags(
report_state.get_total_llm_cost(),
max_budget_usd,
interactive=interactive,
)
await coordinator.reset_budget_stops(
budget_stopped=budget_stopped,
reserve_stopped=reserve_stopped,
budget_paused=interactive and coordinator.budget_paused,
)
for aid, parent in coordinator.parent_of.items():
if parent is None:
root_id = aid
break
if root_id is None:
raise RuntimeError(
f"Cannot resume scan {scan_id}: agents.json has no root agent (parent=None)",
)
logger.info(
"Resume: restored coordinator with %d agent(s); root=%s",
len(coordinator.statuses),
root_id,
)
else:
root_id = uuid.uuid4().hex[:8]
logger.info("Bringing up sandbox session for scan %s", scan_id)
bundle = await session_manager.create_or_reuse(
scan_id,
image=image,
local_sources=local_sources or [],
extra_files=extra_files,
status_sink=status_sink,
)
report("Waiting for the first model response")
logger.info("Sandbox ready for scan %s", scan_id)
sandbox_session = bundle["session"]
async def _spill_to_workspace(output_id: str, text: str) -> str | None:
"""Write an oversized tool result into the sandbox; return its path or None."""
path = f"{WORKSPACE_SPILL_DIR}/{output_id}.txt"
try:
await sandbox_session.write(Path(path), io.BytesIO(text.encode("utf-8")))
except Exception:
logger.exception("failed to spill tool output to sandbox workspace")
return None
return path
configure_spill_writer(_spill_to_workspace)
sessions_to_close: list[SQLiteSession] = []
mcp_servers: list[MCPServer] = []
try:
targets = scan_config.get("targets") or []
scan_mode = str(scan_config.get("scan_mode") or "deep")
is_whitebox = any(t.get("type") == "local_code" for t in targets)
diff_scope = scan_config.get("diff_scope")
is_diff_scoped = bool(isinstance(diff_scope, dict) and diff_scope.get("active"))
skills = list(scan_config.get("skills") or [])
root_task = build_root_task(scan_config)
model_settings = make_model_settings(
settings.llm.reasoning_effort,
model_name=resolved_model,
force_required_tool_choice=settings.llm.force_required_tool_choice,
request_timeout=settings.llm.timeout,
prompt_cache=settings.llm.prompt_cache,
extra_headers=settings.llm.extra_headers,
)
run_config = RunConfig(
model=resolved_model,
model_provider=StrixProvider(),
model_settings=model_settings,
sandbox=SandboxRunConfig(client=bundle["client"], session=bundle["session"]),
trace_include_sensitive_data=False,
# A hallucinated tool name is a recoverable model mistake, not a scan-ending
# error: hand it back as a tool result so the agent can correct itself.
tool_not_found_behavior="return_error_to_model",
)
hooks = ReportUsageHooks(
model=resolved_model,
max_budget_usd=max_budget_usd,
max_turns=max_turns,
interactive=interactive,
)
if interactive:
coordinator.set_budget_extender(hooks.extend_budget)
scope_context = build_scope_context(scan_config)
root_context = _merge_root_prompt_context(scope_context, extra_system_prompt_context)
root_instructions = _compose_root_instructions_override(
root_instructions_override,
skills=skills,
scan_mode=scan_mode,
is_whitebox=is_whitebox,
is_diff_scoped=is_diff_scoped,
interactive=interactive,
system_prompt_context=root_context,
)
# Connect any MCP servers the user listed in ~/.strix/mcp-servers.json and
# register their tools before the agent is built. Fail-open: a missing
# config, or a server that will not connect, must never break a run.
from strix.tools.mcp import connect_mcp_servers, load_user_mcp_configs
try:
user_mcp_configs = load_user_mcp_configs()
if user_mcp_configs:
connections = await connect_mcp_servers(user_mcp_configs)
mcp_servers = [c.server for c in connections]
# Recorded even when nothing connected, so a resumed run does not
# keep attributing tool calls to servers it no longer has.
_record_mcp_connections(connections)
if connections:
report(_mcp_startup_summary(connections))
notes_block = _mcp_connection_notes(connections)
if notes_block:
root_task = f"{root_task}\n\n{notes_block}"
except Exception:
logger.exception("Failed to connect user MCP servers; continuing without them")
root_agent = build_strix_agent(
name="Root Agent",
skills=skills,
is_root=True,
scan_mode=scan_mode,
is_whitebox=is_whitebox,
is_diff_scoped=is_diff_scoped,
interactive=interactive,
chat_completions_tools=chat_completions_tools,
strict_tool_schemas=strict_tool_schemas,
system_prompt_context=root_context,
instructions_override=root_instructions,
)
if not is_resume:
await coordinator.register(
root_id,
"Root Agent",
parent_id=None,
task=root_task,
skills=skills,
)
child_agent_builder = make_child_factory(
scan_mode=scan_mode,
is_whitebox=is_whitebox,
is_diff_scoped=is_diff_scoped,
interactive=interactive,
chat_completions_tools=chat_completions_tools,
strict_tool_schemas=strict_tool_schemas,
system_prompt_context=scope_context,
)
async def spawn_child_agent(**kwargs: Any) -> dict[str, Any]:
return await start_child_agent(
coordinator=coordinator,
factory=child_agent_builder,
agents_db_path=agents_db,
sessions_to_close=sessions_to_close,
run_config=run_config,
max_turns=max_turns,
interactive=interactive,
event_sink=event_sink,
hooks=hooks,
**kwargs,
)
context: dict[str, Any] = {
"coordinator": coordinator,
"sandbox_session": bundle["session"],
"caido_client": bundle["caido_client"],
"agent_id": root_id,
"parent_id": None,
"interactive": interactive,
"spawn_child_agent": spawn_child_agent,
"scan_targets": build_scan_targets(scan_config),
"max_context_images": settings.runtime.max_context_images,
}
root_session = open_agent_session(root_id, agents_db)
sessions_to_close.append(root_session)
await coordinator.attach_runtime(root_id, session=root_session)
if is_resume:
await respawn_subagents(
coordinator=coordinator,
factory=child_agent_builder,
agents_db_path=agents_db,
sessions_to_close=sessions_to_close,
run_config=run_config,
max_turns=max_turns,
interactive=interactive,
parent_ctx=context,
root_id=root_id,
event_sink=event_sink,
hooks=hooks,
)
initial_input: Any = [] if is_resume else root_task
# Resume + new ``--instruction``: SDK replay drives root from
# agents.db with ``initial_input=[]``, so a brand-new instruction
# passed on the resume CLI would otherwise be silently ignored.
# Inject it as a fresh user message in root's SDK session; the
# next run cycle will replay it with the rest of the session.
resume_instruction = str(scan_config.get("resume_instruction") or "").strip()
if is_resume and resume_instruction:
await coordinator.send(
root_id,
{
"from": "user",
"type": "instruction",
"priority": "high",
"content": resume_instruction,
},
)
logger.info(
"Resume: injected new instruction into root SDK session (len=%d)",
len(resume_instruction),
)
async with coordinator._lock:
root_status = coordinator.statuses.get(root_id)
result = await run_agent_loop(
agent=root_agent,
initial_input=initial_input,
run_config=run_config,
context=context,
max_turns=max_turns,
coordinator=coordinator,
agent_id=root_id,
interactive=interactive,
session=root_session,
start_parked=bool(interactive and is_resume and root_status != "running"),
event_sink=event_sink,
hooks=hooks,
)
if not interactive and result is not None:
final = getattr(result, "final_output", None)
scan_completed = False
if isinstance(final, str):
try:
parsed = json.loads(final)
scan_completed = bool(isinstance(parsed, dict) and parsed.get("scan_completed"))
except (ValueError, TypeError):
scan_completed = False
elif isinstance(final, dict):
scan_completed = bool(final.get("scan_completed"))
if not scan_completed:
logger.error(
"Scan %s ended without calling finish_scan. The agent "
"emitted a text-only turn instead of a lifecycle tool call, "
"so no executive report was written. Final output (first "
"300 chars): %r",
scan_id,
str(final)[:300],
)
return result # noqa: TRY300
except BudgetExceededError as exc:
logger.info("Scan %s stopped: %s", scan_id, exc)
if root_id is not None:
with contextlib.suppress(Exception):
await coordinator.set_status(root_id, "stopped")
return None
except RateLimitError as exc:
logger.warning(
"Scan %s stopped: persistent rate limit from the LLM provider (%s). "
"Resume with 'strix --resume %s' once the limit clears.",
scan_id,
exc,
scan_id,
)
if root_id is not None:
with contextlib.suppress(Exception):
await coordinator.set_status(root_id, "stopped")
return None
except (asyncio.CancelledError, KeyboardInterrupt):
logger.info("Scan %s interrupted by the user", scan_id)
if root_id is not None:
with contextlib.suppress(Exception):
await coordinator.set_status(root_id, "running")
raise
except BaseException:
logger.exception("Strix scan %s failed", scan_id)
if root_id is not None:
with contextlib.suppress(Exception):
await coordinator.set_status(root_id, "failed")
raise
finally:
configure_spill_writer(None)
# Settle descendants before closing sessions: on a clean finish a child
# can still be mid-turn, and closing its session underneath it crashes it.
if root_id is not None:
with contextlib.suppress(Exception):
await coordinator.cancel_descendants(root_id)
for s in sessions_to_close:
with contextlib.suppress(Exception):
s.close()
for mcp_server in mcp_servers:
with contextlib.suppress(Exception):
await mcp_server.cleanup() # type: ignore[no-untyped-call]
with contextlib.suppress(Exception):
await coordinator._maybe_snapshot()
if cleanup_on_exit:
logger.info("Tearing down sandbox session for scan %s", scan_id)
await session_manager.cleanup(scan_id)
logger.info("Strix scan %s done", scan_id)
teardown_logging()