NAS Neuron — Claims Engine POC

A claims-validation app for NAS NEURON Health Services. The backend turns an editable rule set into a GoRules ZEN decision model, publishes it to object storage, and evaluates claims against the live ZEN Agent. The frontend is the operator console.

Security model: the ZEN access token and the iDrive e2 (S3) credentials live only on the backend. The browser talks exclusively to the .NET API; it never sees the token or storage keys.

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Run in Visual Studio 2022 (no Node required)

The Angular UI is pre-compiled and bundled into the backend's wwwroot. The .NET app serves the UI and the API together on one port, so nothing JavaScript runs on your machine — no npm, no Node, nothing for group policy / AppLocker to block. You only need the .NET 8 SDK and Visual Studio 2022.

1. File → Open → Project/Solution and choose NasNeuron.ClaimsEngine.sln.
2. (Optional, needed only to save rules) Open backend/NasNeuron.ClaimsApi/Properties/launchSettings.json and paste your iDrive e2 keys into the empty AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY values.
3. Press F5.

The browser opens to http://localhost:5080 and the whole app — UI plus API — runs from there. Members and Claims work immediately on the seeded sample data. Swagger is at /swagger.

Changing the UI later: the frontend source lives in frontend/ for reference, but editing it requires rebuilding the Angular bundle (ng build), which needs Node — so do that on a machine where Node is allowed, then copy frontend/dist/frontend/browser/* into backend/NasNeuron.ClaimsApi/wwwroot/. The backend logic (rules, ZEN, storage) is pure C# and you can iterate on it freely in Visual Studio.

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Architecture

Angular SPA  ──HTTP──>  .NET 8 Web API  ──S3 PUT──>  iDrive e2 bucket (gorules-poc)
(operator UI)           (rules + claims)                      │
                              │                                │ polls every ~5s
                              └────────── evaluate ───────────> GoRules ZEN Agent (Render)
                                       (X-Access-Token)         hot-reloads on change

• Medical Cases — the rule set. Editing a rule rebuilds the JDM, repackages the zip, and uploads it to the bucket. The agent hot-reloads within ~5s.
• Members — directory with a detail panel.
• Claims — history plus a New claim modal that evaluates against the live ruleset.

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Prerequisites

• .NET 8 SDK (this is all you need to run the app)
• iDrive e2 (S3-compatible) credentials with write access to the gorules-poc bucket (only needed to save rules)
• The ZEN Agent reachable at the configured base URL (only needed to evaluate claims)
• Node.js 20+ — not required to run; only needed if you want to rebuild the UI from source

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Running the backend

cd backend/NasNeuron.ClaimsApi

# storage credentials (required for saving rules)
export AWS_ACCESS_KEY_ID=your_idrive_access_key
export AWS_SECRET_ACCESS_KEY=your_idrive_secret_key

dotnet run

API: http://localhost:5080 · Swagger (dev): http://localhost:5080/swagger · Health: /health

Non-secret config lives in appsettings.json and can be overridden by environment variables (double-underscore syntax):

Setting	Default	Env override
Zen:AgentBaseUrl	https://agent-latest-jl93.onrender.com	Zen__AgentBaseUrl
Zen:AccessToken	nnhs-poc-token	Zen__AccessToken
S3:ServiceUrl	https://s3.eu-west-3.idrivee2.com	S3__ServiceUrl
S3:Bucket	gorules-poc	S3__Bucket
S3:ObjectKey	claim_validation.zip	S3__ObjectKey
Cors:Origins	http://localhost:4200	Cors__Origins__0
(S3 credentials)	—	AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY

Rebuilding the frontend (optional)

You don't need this to run the app — the compiled UI already ships in backend/NasNeuron.ClaimsApi/wwwroot. Only if you change the Angular source, on a machine where Node is allowed:

cd frontend
npm install
ng build
# then copy dist/frontend/browser/* into ../backend/NasNeuron.ClaimsApi/wwwroot/

The production build calls the API at the relative path /api (src/environments/environment.ts), so it works served same-origin by the backend with no CORS or proxy needed.

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API

Method	Path	Purpose
GET	/api/rules	List rules
GET	/api/rules/{code}	Get one rule
GET	/api/rules/jdm	Current JDM document (preview)
PUT	/api/rules/{code}	Save a rule → rebuild JDM → zip → upload (hot-reload)
GET	/api/members	List members
GET	/api/members/{id}	Member detail
GET	/api/claims	Claims history
POST	/api/claims/evaluate	Evaluate a claim via the ZEN Agent (optionally records it)

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The save-rule flow

PUT /api/rules/{code} runs entirely server-side:

1. Update/insert the rule in the in-memory set (the PASS catch-all stays last).
2. JdmBuilder serializes the full set into a ZEN decision-table graph (inputNode → decisionTableNode → outputNode, hit policy first).
3. ZipPackager builds the bundle in memory:

   claim_validation.zip
   ├── .config/project.json
   └── claim_validation.json
   

4. S3Uploader PUTs the zip to gorules-poc, overwriting claim_validation.zip (path-style addressing, payload signing disabled for S3-compatible storage).
5. The ZEN Agent polls the bucket and hot-reloads within ~5s.

If credentials are missing the endpoint returns 503 with a clear message; an upload failure returns 502. The UI surfaces both in the publish pipeline.

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The rule set

Evaluated top-to-bottom, first match wins:

Code	Condition	Decision
T01	Treatment date older than 1 year	rejected
T02	Treatment date outside the coverage window (2025-07-01 → 2026-06-30)	rejected
G01	Treatment country excluded, or not in the included list	rejected
M01	gender = male AND claimType = maternity	rejected
M02	claimType = pediatric AND age > 17	rejected
W01	claimType = dental AND age > 65	warning
PASS	catch-all	approved

G01 exposes editable included and excluded country collections in the UI; editing them and saving changes evaluation immediately. T02 exposes editable from/to dates.

ZEN expression dialect

JdmBuilder emits these ZEN Expression Language cells. The backend injects today into the evaluation context so date rules are deterministic:

• T01: date(today) - date(treatmentDate) > duration("365d")
• T02: date(treatmentDate) < date("2025-07-01") or date(treatmentDate) > date("2026-06-30")
• G01: country in ["North Korea","Syria"] or not (country in ["UAE","Saudi Arabia", …])
• M01/M02/W01: unary tests in the bound columns (gender, age, claimType), e.g. gender cell "male", age cell > 17.
• Output cells are quoted ZEN string literals, e.g. "rejected".

Tune against your agent build. Exact date/duration semantics vary slightly between ZEN engine versions. GET /api/rules/jdm returns the exact document being produced — diff it against what your agent expects and adjust the expressions in Services/JdmBuilder.cs if a rule misfires.

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Notes / caveats

• Rules, members, and claims are held in memory and reset on backend restart (POC scope). Swap RuleStore / ClaimStore / SeedData for a database when productionizing.
• The logo is a placeholder slot in the sidebar (AppComponent); drop the official mark in and replace the placeholder block.
• This repository was assembled in an environment without the .NET SDK, so the backend was not compiled here; build it with dotnet build on your machine. The frontend TypeScript was type-checked.