---

Verified — 36/36 E2E Checks Passed

Every Sylo subsystem has been end-to-end tested against real infrastructure — no mocks, no simulation:

Subsystem	What Was Tested	Status
Checkpoint Recovery	Real Groq LLM call → crash → resume → completed step skipped from disk checkpoint	✅
Approval Gates	Real HTTP server on localhost:7749 → auto-approve click → pipeline resumed	✅
LangGraph Integration	Real 2-node StateGraph + SyloGraph wrapper with live Groq inference	✅
OpenAI Agents SDK Integration	Real Agent + Runner wrapped with wrap_agent with live Groq inference	✅
CrewAI Integration	Real Crew + Task wrapped with SyloCrew with live Groq inference	✅
Trust Broker	ctx.access() enforced at runtime — allowed reads pass, undeclared writes blocked	✅
Audit Engine	get_summary(), replay(dry_run=True), pretty_print_audit() against real executions	✅
CLI	sylo executions list and sylo audit <id> against live stored data	✅
Disk Persistence	Checkpoint JSON, audit JSONL, execution records, and approval files validated on disk	✅

156 automated tests + 36 E2E integration checks = full coverage & honesty.
Every code snippet and feature statement in this README is automated and verified in tests/test_readme_snippets.py.
Live infrastructure E2E proofs are located in examples/e2e_test_suite.py, examples/test_openai_agents_integration.py, and examples/test_crewai_integration.py.

---

Why Sylo?

When autonomous AI agents move from local prototypes to production environments, unexpected edge cases inevitably arise: API rate limits trigger crashes, hallucinations lead to unauthorized resource access, or destructive actions fire without oversight.

Sylo wraps your existing workflows (LangGraph, CrewAI, OpenAI Agents SDK, or vanilla Python) with mission-critical reliability and safety rails:

Challenge in Production	Without Sylo	With Sylo SDK
Pipeline Failures & Crashes	A 5-step workflow crashes at step 4 due to an API timeout. You restart from step 1, burning duplicated LLM tokens and wasting minutes.	Instant Checkpoint Recovery. Sylo automatically resumes execution exactly at step 4, returning cached results for steps 1–3 and saving up to 90% in token costs.
Agent Over-Privilege & Leaks	An autonomous email assistant hallucinates and accesses internal customer databases or file systems it shouldn't touch.	Zero-Trust Runtime Enforcement. Declare granular permissions (can_read, can_write) per step. Unauthorized access attempts are blocked and logged instantly.
Irreversible Destructive Actions	An agent deletes customer records, initiates financial transfers, or modifies production databases automatically without notice.	Human Approval Gates. Execution automatically pauses at defined gates, dispatching Slack/Email/Webhook notifications and waiting for explicit human sign-off.
Compliance & Traceability	Debugging agent behavior requires sifting through scattered text logs with no standardized cost metrics or audit trails.	Immutable Audit Logging. Every step, retry, cost estimate, and permission check produces standardized JSONL or Redis Stream audit records.

---

Architecture & Data Flow

Sylo acts as an asynchronous middleware layer between your pipeline logic and your infrastructure storage.

graph TD
    subgraph App [Your Application Pipeline]
        P[sylo.pipeline context] --> S1["@sylo.step: Fetch Data"]
        S1 --> S2["@sylo.step + @sylo.trust: Transform & Access API"]
        S2 --> S3["@sylo.step + @sylo.requires_approval: Execute Action"]
    end

    subgraph Core [Sylo Core Engine]
        C[Checkpoint Engine]
        T[Trust & Security Broker]
        A[Approval Gate Engine]
    end

    subgraph Store [Persistence Layer]
        LStore[(Local Disk JSONL)]
        RStore[(Redis / Streams)]
        CStore[(Sylo Cloud API)]
    end

    S1 <-->|Read Cache / Save State| C
    S2 <-->|Validate Permissions| T
    S3 <-->|Pause & Notify / Poll Decision| A

    C --> Store
    T --> Store
    A --> Store

---

Quickstart

1. Installation

Install the Sylo SDK via pip:

pip install sylo-sdk

For Redis storage support in production environments:

pip install "sylo-sdk[redis]"

2. Five-Minute Integration

Here is a complete, production-ready pipeline demonstrating Checkpointing, Permission Enforcement, and Human Approval Gates working together:

import asyncio
import httpx
import sylo

# 1. Initialize Sylo SDK (defaults to local disk storage in development)
sylo.init(project="customer-operations", environment="development")


# 2. Define pipeline steps using decorators
@sylo.step("fetch-customer-data", max_retries=3, retry_delay=1.0)
@sylo.trust(can_read=["crm.customers"])
async def fetch_customer(ctx: sylo.Context, customer_id: str) -> dict:
    """Fetch customer details through permission-checked context access."""
    
    async def _api_call():
        # Simulate external API call
        return {"id": customer_id, "name": "Acme Corp", "status": "inactive"}

    # Sylo verifies at runtime that "crm.customers" is allowed for reading
    return await ctx.access("crm.customers", action="read", handler=_api_call)


@sylo.step("analyze-churn-risk")
async def analyze_churn(ctx: sylo.Context) -> dict:
    """Analyze risk using previous step outputs."""
    # Retrieve cached output from the previous step without re-running it
    customer = ctx.get_output("fetch-customer-data")
    
    # In production, pass real token counts from your LLM provider's response object.
    # See examples/real_world_test.py for a complete working example with Groq.
    ctx.record_token_usage(prompt_tokens=450, completion_tokens=120, model="gpt-4o")
    
    return {"customer_id": customer["id"], "risk_score": 0.89, "recommendation": "terminate"}


@sylo.step("delete-account")
@sylo.requires_approval(
    title="Confirm Account Deletion",
    description="About to permanently delete account for {customer_id} (Risk Score: {risk_score})",
    action_class="destructive",
    timeout_hours=24,
    on_timeout="abort",
    notify=["slack", "email"],
    metadata_keys=["customer_id", "risk_score"]
)
async def delete_account(ctx: sylo.Context) -> dict:
    """Dangerous action guarded by a human approval gate."""
    customer_id = ctx.metadata["customer_id"]
    return {"status": "deleted", "customer_id": customer_id}


# 3. Run the pipeline context
async def main():
    async with sylo.pipeline("churn-remediation", metadata={"customer_id": "cust_8842"}) as pipe:
        data = await fetch_customer(pipe.context, "cust_8842")
        analysis = await analyze_churn(pipe.context)
        
        # Merge analysis results into metadata so the approval gate template can render them
        pipe.context.metadata.update(analysis)
        
        result = await delete_account(pipe.context)
        print(f"Pipeline finished successfully: {result}")

if __name__ == "__main__":
    asyncio.run(main())

Console Output During Execution

When reaching the approval gate in local development mode, Sylo automatically spins up a background HTTP server on port 7749 and prints a clean, actionable prompt to your terminal:

[APPROVAL REQUIRED] Sylo Approval Required
  Pipeline: churn-remediation
  Step: delete-account
  Action: About to permanently delete account for cust_8842 (Risk Score: 0.89) (DESTRUCTIVE)

  Approve: http://localhost:7749/approve/d3b07384-d113-4c4e-9c81-bcc318231221
  Reject:  http://localhost:7749/reject/d3b07384-d113-4c4e-9c81-bcc318231221

  Expires in: 24.0 hours
  Waiting for decision...

Clicking either URL instantly registers your decision, logs the audit event, and resumes or aborts the asynchronous pipeline.

---

Core Features

1. Smart Checkpointing & Cost Tracking

Wrap any async or sync function with @sylo.step("step-name"). Every successful execution is serialized and persisted to storage. If a downstream step crashes or raises an exception, subsequent reruns skip completed steps instantly.

@sylo.step("generate-report", max_retries=5, retry_delay=2.0)
async def generate_report(ctx: sylo.Context) -> dict:
    # Access outputs from earlier steps safely
    raw_data = ctx.get_output("fetch-data")
    
    # Track model usage
    ctx.record_token_usage(prompt_tokens=1200, completion_tokens=350, model="claude-3-5-sonnet")
    return {"report_url": "https://..."}

• Automatic Retries: Exponential backoff with jitter on network failures.
• Token & Cost Ledger: Automatically tallies prompt and completion tokens across models (gpt-4o, claude-3-5-sonnet, etc.), estimating real-time USD costs in the execution summary.

2. Zero-Trust Security Broker

Prevent agents from performing unauthorized network requests or file modifications by declaring explicit capability manifests.

@sylo.step("send-slack-notification")
@sylo.trust(
    can_read=["slack.channels", "users.profile"],
    can_write=["slack.messages"],
    can_execute=[],
    can_delete=[]
)
async def notify_team(ctx: sylo.Context):
    # This succeeds: matches declared can_write pattern
    await ctx.access("slack.messages", action="write", handler=post_message)
    
    # This raises SyloPermissionError and logs an audit violation immediately!
    await ctx.access("aws.s3.buckets", action="delete", handler=delete_bucket)

3. Human Approval Gates

Guard destructive, financial, or external actions behind asynchronous human reviews.

@sylo.requires_approval(
    title="Wire Transfer Request",
    description="Transferring ${amount} to account {recipient}",
    action_class="financial",
    timeout_hours=4.0,
    on_timeout="escalate",        # Options: "abort", "auto_approve", "escalate"
    notify=["slack", "webhook"],  # Dispatches Block Kit / HMAC webhooks
    metadata_keys=["amount", "recipient"]
)

• Programmatic Fallbacks: You can also approve or reject requests programmatically from external backend webhooks or CLI scripts via await sylo.approve(approval_id, decided_by="supervisor").

4. Immutable Audit Trails

Every execution maintains an append-only sequence of immutable events (PIPELINE_STARTED, STEP_COMPLETED, PERMISSION_VIOLATION, APPROVAL_REQUESTED, APPROVAL_DECISION).

In local mode, logs are formatted as standard JSONL (~/.sylo/executions/{id}/audit.jsonl). In production Redis storage, events are streamed to high-throughput Redis Streams (XRANGE), providing complete auditability for SOC2 and enterprise compliance.

5. Cross-Thread Context Propagation

Some frameworks (e.g. LangChain, CrewAI) dispatch work to thread pools or new event loops. Python's ContextVar values are not automatically inherited by worker threads, which means @sylo.step would lose track of the active pipeline.

Sylo detects this and raises a SyloContextError with actionable guidance instead of silently falling back to passthrough. To fix it, wrap the callable with sylo.propagate_context() before dispatching it:

import asyncio
import sylo

@sylo.step("call-tool")
async def call_tool(ctx: sylo.Context) -> dict:
    # Wrap the sync function to carry the pipeline context into the thread
    wrapped = sylo.propagate_context(my_sync_tool)

    loop = asyncio.get_event_loop()
    result = await loop.run_in_executor(None, wrapped, arg1, arg2)
    return {"result": result}

propagate_context() snapshots the current ContextVar state and replays it inside the worker thread, so @sylo.step, trust enforcement, and audit logging all work correctly across the boundary.

---

Storage Backends

Sylo provides a standardized interface across multiple storage engines, allowing you to develop locally without infrastructure overhead and deploy to production seamlessly.

Storage Backend	Configuration	Use Case & Persistence Guarantees
Local File Store (Default)	storage="local"	Perfect for local development and CI testing. Stores execution manifests, checkpoints, and JSONL audit logs under ~/.sylo/executions/. Fails silently on network errors so development workflows are never blocked.
Redis & Redis Streams	storage="redis"	Built for high-concurrency production workloads. Uses Redis key-value storage for state checkpoints and append-only Redis Streams for real-time audit event distribution.
Sylo Cloud API	storage="cloud"	Enterprise managed cloud platform. Syncs executions, approval queues, and telemetry directly to your centralized Sylo Cloud dashboard.

---

Configuration Matrix

Initialize Sylo programmatically at application startup or via standard environment variables:

Programmatic Configuration

import sylo

sylo.init(
    project="autonomous-researcher",
    api_key="sylo_live_xxxxx",
    environment="production",           # "development" | "staging" | "production"
    storage="redis",                    # "local" | "redis" | "cloud"
    redis_url="redis://redis-master:6379/0",
    notifications={
        "slack": {"webhook_url": "https://hooks.slack.com/services/..."},
        "email": {"provider": "resend", "api_key": "re_123456", "from": "saketjndl2005@gmail.com"}
    }
)

Environment Variables

Variable	Description	Default
SYLO_PROJECT	Identifier for the pipeline group or application	default
SYLO_ENVIRONMENT	Current runtime environment (development, production)	development
SYLO_STORAGE	Storage backend driver (local, redis, cloud)	local
SYLO_API_KEY	API key when communicating with Sylo Cloud	None
SYLO_REDIS_URL	Connection string for Redis backend	redis://localhost:6379

---

Framework Integrations

Sylo wraps around your existing agent code without replacing your framework. Every adapter has been verified in production against real LLM infrastructure.

Framework	Adapter / Class	Verified Against	E2E Status
LangGraph	SyloGraph	Live Groq (openai/gpt-oss-20b)	✅ 100% Tested
OpenAI Agents SDK	wrap_agent (WrappedAgent)	Live Groq (openai/gpt-oss-20b)	✅ 100% Tested
CrewAI	SyloCrew	Live Groq (groq/openai/gpt-oss-20b)	✅ 100% Tested
Vanilla Python	@sylo.step, @sylo.trust	Async/Sync Python pipelines	✅ 100% Tested

1. LangGraph Integration

Wrap any LangGraph StateGraph with SyloGraph to automatically checkpoint individual nodes and skip completed steps upon resume:

from langgraph.graph import StateGraph, START, END
from sylo.integrations.langgraph import SyloGraph
import sylo

# Define your LangGraph nodes
def research_node(state: dict) -> dict:
    return {"findings": "..."}

base_graph = StateGraph(dict)
base_graph.add_node("research", research_node)
base_graph.add_edge(START, "research")
base_graph.add_edge("research", END)

# Wrap with SyloGraph
graph = SyloGraph(base_graph, pipeline_name="langgraph-researcher")
app = graph.compile()

async def run():
    async with sylo.pipeline("langgraph-researcher"):
        return app.invoke({"topic": "quantum computing"})

2. OpenAI Agents SDK Integration

Wrap standard OpenAI Agent instances with wrap_agent (WrappedAgent). Sylo intercepts execution, records token usage automatically from Runner.run(), and caches step outputs:

from openai import AsyncOpenAI
from agents import Agent, Runner, set_tracing_disabled
from agents.models.openai_chatcompletions import OpenAIChatCompletionsModel
from sylo.integrations.openai_agents import wrap_agent
import sylo

# Disable Agents SDK telemetry when pointing at non-OpenAI endpoints (e.g. Groq)
set_tracing_disabled(True)

client = AsyncOpenAI(base_url="https://api.groq.com/openai/v1", api_key="...")
model = OpenAIChatCompletionsModel(model="openai/gpt-oss-20b", openai_client=client)

agent = Agent(name="Researcher", instructions="Analyze breakthroughs.", model=model)
wrapped = wrap_agent(agent, step_name="research-step")

async def run():
    async with sylo.pipeline("openai-agents-pipeline") as pipe:
        return await wrapped.run("Analyze recent quantum breakthroughs.")

3. CrewAI Integration

Wrap your agents and tasks with SyloCrew. Sylo executes tasks as isolated mini-crews asynchronously inside thread pools, allowing fine-grained checkpoint recovery at the task level:

import litellm
litellm.drop_params = True  # Required for non-native providers (e.g., Groq)

from crewai import Agent, Task
from sylo.integrations.crewai import SyloCrew
import sylo

researcher = Agent(role="Researcher", goal="Research topic", backstory="Expert researcher", llm="groq/openai/gpt-oss-20b")
task1 = Task(description="Research quantum computing", agent=researcher, expected_output="Facts summary")

crew = SyloCrew(agents=[researcher], tasks=[task1])

async def run():
    async with sylo.pipeline("crewai-pipeline") as pipe:
        return await crew.kickoff_async()

Known Limitations & Compatibility Notes

• Thread & Event-Loop Boundaries: Frameworks that dispatch work to thread pools (e.g. asyncio.to_thread, run_in_executor) do not automatically carry Python ContextVar values into worker threads. If a @sylo.step is invoked from a worker thread without propagation, Sylo raises SyloContextError with guidance. Wrap the callable with sylo.propagate_context() before dispatching — see Cross-Thread Context Propagation above.
• CrewAI & Groq / LiteLLM Compatibility: When using third-party OpenAI-compatible endpoints like Groq with CrewAI, CrewAI injects prompt-caching markers (cache_breakpoint) into message dictionaries. Sylo automatically patches crewai.llms.cache.mark_cache_breakpoint and strips unsupported message flags during execution to prevent 400 Bad Request API errors.
• OpenAI Agents SDK Tracing: When pointing OpenAIChatCompletionsModel at non-OpenAI endpoints (such as Groq or local vLLM instances), make sure to call agents.set_tracing_disabled(True) to prevent the SDK from attempting to phone home trace telemetry to OpenAI servers.
• Async Execution: Both OpenAI Agents SDK (Runner.run()) and CrewAI (kickoff()) run synchronously by default. Sylo wraps them seamlessly inside asyncio.to_thread executors so they integrate natively into non-blocking async Sylo pipelines.

---

Contributing & Development

We welcome contributions from the open-source community!

# 1. Clone the repository
git clone https://github.com/saketjndl/Sylo.git
cd Sylo

# 2. Install dependencies in editable mode
pip install -e ".[dev,redis]"

# 3. Run the test suite (100% async test coverage)
pytest tests/ -v

---

License

Sylo is open-source software licensed under the MIT License.