open-swe/AGENTS.md

AGENTS.md

This file provides guidance to Coding Agents when working with code in this repository.

Project

Open SWE is an open-source coding-agent framework built on LangGraph + Deep Agents (deepagents.create_deep_agent). It runs as a LangGraph app: each thread spawns its own isolated cloud sandbox, and the agent is invoked from Slack, Linear, or GitHub (PR comments, plus auto-review on opened / ready-for-review).

A separate reviewer graph runs read-only code reviews on PRs, and a review-style analyzer graph learns per-repo review style from historical PRs.

Commands

Dependencies are managed with uv. Tests use pytest (asyncio_mode = "auto"). Lint/format is ruff (line-length 100, target py311). requires-python = ">=3.11"; langgraph.json pins the runtime to 3.12.

make install            # uv pip install -e .
make dev                # uv run langgraph dev — serves all three graphs + the FastAPI app from langgraph.json
make run                # uvicorn agent.webapp:app --reload --port 8000 (FastAPI only, no LangGraph runtime)
make test               # uv run pytest -vvv tests/
make test TEST_FILE=tests/test_open_pr_middleware.py    # single test file
uv run pytest -vvv tests/test_open_pr_middleware.py::test_name  # single test
make lint               # ruff check + ruff format --diff
make format             # ruff format + ruff check --fix

langgraph.json declares three graph entrypoints and the FastAPI app, all served together by langgraph dev:

Graph	Entrypoint	Purpose
agent	agent.server:get_agent	Main coding agent (Slack/Linear/GitHub-triggered).
reviewer	agent.reviewer:get_reviewer_agent	Read-only PR reviewer. Findings model + publish_review.
analyzer	agent.analyzer:get_analyzer	Learns per-repo reviewer style from historical PRs and this reviewer's own finding outcomes.
ci_monitor	agent.ci_monitor:get_ci_monitor	Polling fallback for CI auto-fix: each tick sweeps open agent-authored PRs for failing checks / merge conflicts via agent.ci_autofix.sweep_open_prs.

The FastAPI app is agent.webapp:app.

CI auto-fix ("PR babysitting") lives in agent/ci_autofix.py: when a CI check fails (webhook check_run / check_suite / workflow_run / status) or a reviewer leaves actionable feedback on a PR Open SWE opened, it locates the originating agent thread (by pr_url metadata) and dispatches a confidence-gated fix run on the agent graph. Gated by the per-user auto_fix_ci profile flag, the enabled-repos opt-in, and a per-PR @open-swe autofix on|off toggle (agent/dashboard/autofix_state.py). Skip-rules (base-branch failures, human commits, same-head dedupe, batching while runs are active, loop cap) all live in ci_autofix.py.

Architecture

Entrypoints

• agent/server.py → get_agent(config) — main graph factory. Called per-thread. Resolves the GitHub token, gets-or-creates the sandbox for the thread, resolves the team/profile/per-thread model + effort, then constructs a fresh create_deep_agent(...) with the curated tool list and middleware stack. The agent itself is stateless — all per-thread state lives in the sandbox + thread metadata.
• agent/reviewer.py → get_reviewer_agent(config) — reviewer graph factory. Shares ensure_sandbox_for_thread with the main agent but wires a reviewer-only toolset (add_finding, update_finding, list_findings, publish_review, web_search, fetch_url, http_request) and a different system prompt that pins the single-evolving-findings model and the diff-anchored bar for filing a finding. Read-only: no commit/push/PR-opening tools.
• agent/analyzer.py → get_analyzer(config) — small graph that emits a per-repo style prompt via the save_review_style_prompt tool, consumed by the reviewer as a "repository-specific review style" appendix. It runs in one of two modes (analyzer_mode in configurable): bootstrap (cold-start: crawl historical PR reviews) and continual (nightly: refine using this reviewer's own finding outcomes via read_finding_outcomes). Each mode's procedure lives in a deepagents skill (agent/skills/bootstrap-repo-analysis/, agent/skills/continual-learning/) served as virtual files via a CompositeBackend /skills/ route + StateBackend (seeded into the run's files channel by the launcher — never written to the sandbox). Launchers and the per-repo nightly cron live in agent/dashboard/review_style_jobs.py and agent/dashboard/analyzer_cron.py; the cron is registered when bootstrap completes.
• agent/webapp.py — custom FastAPI routes mounted alongside the LangGraph server. Webhooks land here (GitHub, Linear, Slack). Each webhook resolves a deterministic thread_id (so follow-up messages route to the same agent run) and triggers/streams a run via the langgraph_sdk client. Also auto-reviews PRs on opened / ready_for_review events when the repo+author opt in.
• agent/dashboard/ — router mounted under the FastAPI app at startup (app.include_router(dashboard_router)). Owns GitHub OAuth, per-user profiles, admin endpoints, team defaults, enabled-repo lists, review-style management, and the Agents chat thread API used by the UI in ui/.

Sandbox lifecycle (the tricky part)

SANDBOX_BACKENDS (in agent/utils/sandbox_state.py) is an in-process dict keyed by thread_id. Thread metadata persists sandbox_id across processes. ensure_sandbox_for_thread handles four cases:

1. Sandbox cached in memory → ping it (echo ok); recreate on SandboxClientError. Healthy reused sandboxes also get a GitHub-proxy refresh (recreate on failure).
2. Metadata says __creating__ and no cache → reset stale metadata so a fresh sandbox can be created.
3. No sandbox at all → set __creating__ sentinel, create one, persist the real id.
4. Metadata has an id but no cache → reconnect; fall back to recreate on failure.

For SANDBOX_TYPE=langsmith (default), every sandbox creation/refresh also calls _configure_github_proxy with a fresh GitHub App installation token (get_github_app_installation_token). The proxy injects Basic auth for github.com git traffic and Bearer auth for api.github.com so sandbox commands can use GH_TOKEN=dummy gh ... without storing real tokens in the sandbox. Other providers (modal, daytona, runloop, local) skip the proxy step. Provider is selected via SANDBOX_TYPE; factory is agent/utils/sandbox.py:create_sandbox (SANDBOX_FACTORIES maps each provider name to a creator in agent/integrations/).

Every run re-applies git config --global user.name/email for the bot identity, because reused/reconnected sandboxes can lose --global config and Vercel preview deploys reject commits whose author email doesn't resolve to a GitHub account.

Middleware stack (order matters)

Configured in agent/server.py:get_agent, runs around every model call (in this order):

1. SanitizeToolInputsMiddleware — strips/normalizes tool inputs before they reach tools.
2. ModelCallLimitMiddleware (from langchain.agents.middleware) — caps model calls at MODEL_CALL_RECURSION_LIMIT (~half of DEFAULT_RECURSION_LIMIT); exit_behavior="end".
3. ToolErrorMiddleware — catches tool exceptions and surfaces them as tool messages.
4. check_message_queue_before_model — pulls Linear comments / Slack messages that arrived mid-run from the thread queue and injects them as user messages before the next LLM call. This is what makes "message the agent while it's working" work.
5. SlackAssistantStatusMiddleware — keeps the Slack "assistant is typing"-style status up to date around model calls.
6. notify_step_limit_reached — after-agent hook that posts a Slack reply when the agent hits the step limit, so the user gets a clear signal instead of silence.
7. SandboxCircuitBreakerMiddleware — trips the agent out of repeated sandbox failures instead of looping.
8. ModelFallbackMiddleware (optional) — added only when LLM_FALLBACK_MODEL_ID or the per-model default fallback differs from the primary model.
9. SanitizeThinkingBlocksMiddleware — strips malformed empty Anthropic thinking blocks immediately before provider calls.

The agent ends its turn naturally when the model emits a final message with no tool call; there is intentionally no middleware that forces a tool call on every turn.

Other middleware exists in agent/middleware/ (ExcludeToolsMiddleware) but isn't wired into the default agent. The reviewer uses a leaner stack: SanitizeToolInputsMiddleware, ModelCallLimitMiddleware, ToolErrorMiddleware, SlackAssistantStatusMiddleware, SanitizeThinkingBlocksMiddleware.

There is intentionally no after-agent safety net that opens a PR for the agent. The agent itself is responsible for committing, pushing, opening/updating the draft PR, and replying in the source channel — all via GH_TOKEN=dummy gh and slack_thread_reply / linear_comment.

Tools

All tools live in agent/tools/ and are flat-imported via agent/tools/__init__.py. The set is intentionally small and curated — see README "Tools — Curated, Not Accumulated".

Wired into get_agent: http_request, fetch_url, web_search, linear_comment, linear_create_issue, linear_delete_issue, linear_get_issue, linear_get_issue_comments, linear_list_teams, linear_update_issue, request_pr_review, slack_read_thread_messages, slack_thread_reply.

Reviewer-only tools (in agent/reviewer.py): add_finding, update_finding, list_findings, publish_review. The review-style analyzer uses save_review_style (exported as save_review_style_prompt).

Built-in deepagents tools (read_file, write_file, edit_file, ls, glob, grep, execute, write_todos, task for subagent spawning, …) are added by create_deep_agent itself; don't duplicate them.

Models, profiles, and team defaults

Model + reasoning effort are resolved per run in this precedence (highest wins):

1. Per-thread config (agent_model_id + agent_effort in configurable) — set by webhooks/UI.
2. Per-user dashboard profile override (agent/dashboard/agent_overrides.py:load_profile), keyed by resolved GitHub login.
3. Team default model (agent/dashboard/team_settings.py:get_team_default_model("agent")).

Supported model IDs and per-model effort/reasoning rules live in agent/dashboard/options.py. Profile flags also drive run behavior — e.g. profile_create_prs enables the opt-in Always Create PRs policy. Model construction goes through agent/utils/model.py (make_model, provider_model_kwargs, fallback_model_id_for).

Auth

• GitHub: dual-mode. User OAuth tokens are encrypted at rest in the dashboard OAuth store and cached only in process during a run (utils/auth.py:resolve_github_token, utils/github_token.py). When no user token is available, falls back to a GitHub App installation token (utils/github_app.py). The installation token is also what configures the LangSmith sandbox's GitHub proxy.
• Webhooks: GitHub signatures verified in utils/github_comments.py:verify_github_signature; Slack/Linear handled in their respective utils.
• Dashboard / UI: GitHub OAuth login lives in agent/dashboard/oauth.py and routes.py (/auth/login, /auth/callback, /auth/logout, /me).

Thread-id derivation

Webhooks compute deterministic thread ids so the same Linear issue / Slack thread / PR routes back to the same running agent. See utils/github_comments.py:get_thread_id_from_branch and the equivalents in utils/linear.py / utils/slack.py. Reviewer threads have their own deterministic ids and are tagged with REVIEWER_THREAD_KIND metadata so the FastAPI side can find them.

Conventions

• Tests are unit-only by default (tests/). Integration tests would go under tests/integration_tests/ (currently empty — make integration_tests no-ops if missing).
• New sandbox providers: add a module under agent/integrations/ and wire it into SANDBOX_FACTORIES in agent/utils/sandbox.py. See CUSTOMIZATION.md.
• New tools: add to agent/tools/, export from agent/tools/__init__.py, add to the tools=[...] list in server.py:get_agent (or reviewer.py for reviewer-only tools).
• New middleware: add to agent/middleware/, export from agent/middleware/__init__.py, add to the middleware=[...] list in server.py:get_agent — order is significant (see the stack above).
• New dashboard endpoints: add to agent/dashboard/routes.py. The router is auto-mounted on the FastAPI app.
• New graphs: register the entrypoint in langgraph.json under graphs.
• Minimal-to-no code comments — only when the why isn't obvious from the code.