hncb-fusion-deid-demo/fusion/POLICY_SETUP.md

Fusion policy setup (steps 2, 3-route, 8)

This is the one part that isn't Terraform/CLI — it's configured in the Amplify AI Gateway (Fusion) itself. Below is the flow the gateway must implement. It is the orchestration + transformation layer only; detection and the vault are the separate components it calls.

Endpoints to fill in

• PRESIDIO_URL = http://<presidio-task-ip>:5001/analyze
• VAULT_TABLE = hncb-deid-demo-vault (DynamoDB)
• AGENT_RUNTIME_ARN = printed by scripts/agentcore_setup.sh (step 3)

Ingress policy (advisor request → cloud)

1. Authenticate the advisor and apply the RBAC / business-purpose check.
2. Detect: POST the raw query to PRESIDIO_URL. You get back typed findings: [{entity_type, start, end, score, text}]. (Findings, not redaction.)
3. Mint + splice (Fusion owns this):
   • for each finding, generate a fresh random token — different every request. Convention: CUST_<random> for a PERSON that resolves to a customer, TW_<random> for a TW_ROC_ID, etc.
   • write the reversible entry to the vault: { token, type, value, session_id, expires_at }
   • replace each finding's span in the text with its token.
4. Route: invoke AGENT_RUNTIME_ARN with { "prompt": "<de-identified text>" }.
5. Trace: log the tokenized payload only — never the pre-substitution text.

Egress policy (cloud response → advisor)

1. Receive the agent's de-identified result.
2. Restore: for this session_id, look up the vault and re-attach the real identity (envelope-level here — the talking points are generic, so you prepend "王小明 —"; if any token appears inline, swap it back too).
3. Return { "final": "<restored answer>", "deidentified_prompt": "<what the cloud saw>" } so the UI can show the split view.

Vault item shape (DynamoDB)

{ "token": "CUST_000123", "type": "CUSTOMER", "value": "cust-0001",
  "session_id": "<conv id>", "expires_at": <epoch+ttl> }

Demo-simplest alternative

If wiring all of this into Fusion policy is too much for the first recording, implement steps 2-5 as a thin Fusion flow that calls a small "tokenizer" Lambda (detect → mint → vault write → splice) and a "restore" Lambda on egress. Same architecture on screen, less console clicking. The point of the demo is that the gateway owns the flow and the cloud only ever sees tokens.