Level 2: Certified ArcFlow Systems Engineer

Title: Certified ArcFlow Systems Engineer

Prerequisite: Level 1: Workflow Developer

What certified means at this level

You design graph workflows with conditional routing and joins, operate vector RAG ingest and retrieval, apply retry timeout and fallback patterns, implement HITL approval flows, integrate external callbacks with HMAC verification, configure SDK streaming, and read complex traces including retry events, MemoryRetrieved, and HITL states.

Competencies added over Level 1

Competency	Demonstration
Graph DAG	Branch selection and join nodes with trace proof
Vector RAG	Ingest plus query with `MemoryRetrieved`
Reliability	Retry, timeout, or step fallback on at least one step
HITL	Interrupt and approve via API
External callbacks	Outcome posted with verified auth
Streaming	`run_stream` or `runStream` consumer
Complex traces	Interpret retry and interrupt metadata

Continue with

Topic	Document
Graph	Graph workflows
RAG	Vector RAG pipeline
HITL	HITL overview
External	External callbacks
Streaming	SDK streaming
Traces	Trace event reference
Tutorial	Track D
Tutorial	Track E

Practical project

Build a graph-routed customer support workflow with RAG, HITL escalation, retry configuration, and external webhook notification.

Architecture sketch

text

classify (graph entry)
 ├─ billing branch
 └─ technical branch
 └─ join → answer with RAG
escalation branch → HITL manager approve → external notify webhook

Requirements

Requirement	Detail
Graph routing	At least two conditional branches plus one join
RAG	Knowledge base ingested; answers cite retrieved context in output behavior
HITL	Escalation path interrupts; approve via `POST.../approve/{key}`
Retry	Configure retry on a flaky tool or stub failure injection
External webhook	Post outcome via `report_outcome` or signed HTTP
Server runtime	Use `arcflow-server` for HITL and external paths
Trace pack	Export trace showing `MemoryRetrieved`, graph nodes, interrupt, completion

Suggested examples to compose

Pattern	Example
Graph join	`parallel_search.py`
RAG	`document_qa.py`
HITL	`expense_approval.py`
External	`playwright_stub_callback.py`
Streaming (optional UX)	`chat_stream.py`

Verification commands

bash

docker compose -f docker/docker-compose.server.yml up -d
python your_support_workflow/run.py
bash examples/hitl/approve_cli.sh RUN_ID # when escalated
python examples/external/playwright_stub_callback.py --run-id RUN_ID --status success
curl -s "http://localhost:8080/v1/runs/RUN_ID/trace" -H "Authorization: Bearer dev-secret"

Pass criteria:

Check	Pass
Wrong branch not executed	Graph trace proves branch taken
`MemoryRetrieved` on FAQ path	yes
HITL `Interrupted` then `Completed` after approve	yes
External callback accepted	run advances
Retry event in trace when failure injected	yes
Trace policy	no prompts in exported trace

Known gaps to acknowledge

ID	Impact on project
Graph recovery resume	Graph checkpoint resume partial; design linear recovery fallback
Server SSE streaming	Server SSE streaming deferred; use SDK streaming or poll

Note these in your README.

Self-assessment checklist

Question	Answer must be yes
Can you explain join preconditions?
Can you rotate HITL approval keys conceptually?
Can you verify webhook HMAC without disabling checks?
Can you read `MemoryRetrieved` without seeing chunk text?

Next level

Proceed to Level 3: Platform Engineer for deployment, static product, and trace data policy operations.