# New Domain Hub — Quickstart Guide

**Audience:** A developer starting a new domain hub (dev-hub, ops-hub, fin-hub, etc.)
that will live in its own repository and use inter-hub as the governance substrate.

**Current state:** inter-hub v0.2.0-alpha.1 is running at `http://192.168.178.135:8080`.

---

## Two Patterns — Choose One

### Pattern A: API Consumer Hub (any language, start today)

Your hub is a standalone application that talks to inter-hub via REST API.
No Haskell required. Full framework services available from day one.

**Best for:** Hubs that already have a tech stack (Node, Python, Go, etc.),
prototypes, or teams that want zero build overhead.

### Pattern B: IHP Extension Hub (Haskell, shares build infra)

Your hub is a separate IHP project that runs alongside inter-hub, sharing
the same Nix/GHC installation on haskelseed and optionally the same
PostgreSQL cluster (different schema or database).

**Best for:** Hubs that need server-rendered UI, deep governance integration,
or type-safe access to inter-hub's data model.

---

## Pattern A — API Consumer Hub

### 1. Create an API consumer in inter-hub

Go to `http://192.168.178.135:8080/ApiConsumers` → New.

Fill in:
- **Name:** `dev-hub` (or your hub name)
- **Contact:** your team email
- **Description:** what this hub does

After creating the consumer, go to **API Keys → New** and generate a key
for this consumer. Copy the key — it is shown only once.

### 2. Register your hub

```bash
curl -X POST http://192.168.178.135:8080/api/v2/hubs \
  -H "Authorization: Bearer <your-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Dev Hub",
    "slug": "dev-hub",
    "domain": "dev.example.com",
    "hubKind": "domain"
  }'
```

Save the returned `id` — this is your `hubId` for all subsequent calls.

### 3. Register your type vocabulary

Before creating widgets with domain-specific types, register them via the
inter-hub UI at `/HubCapabilityManifests` → New → select your hub.

In the manifest editor, declare your types:
```json
["dev-pipeline-run", "dev-pr-review", "dev-build-status"]
```

Click **Activate**. See `docs/domain-hub-extension-guide.md` for the full
naming rules and conflict-resolution workflow.

### 4. Register widgets

```bash
curl -X POST http://192.168.178.135:8080/api/v2/widgets \
  -H "Authorization: Bearer <your-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Pipeline Status Panel",
    "widgetType": "dev-pipeline-run",
    "hubId": "<your-hub-id>",
    "viewContext": "pipeline-dashboard"
  }'
```

### 5. Record interaction events

```bash
curl -X POST http://192.168.178.135:8080/api/v2/interaction-events \
  -H "Authorization: Bearer <your-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
    "widgetId": "<widget-id>",
    "eventType": "clicked",
    "userId": "<optional-user-id>",
    "payload": {"button": "retry", "pipeline": "main-ci"}
  }'
```

### 6. What you get for free

Once events are flowing, the inter-hub framework automatically provides:
- Annotation collection on any widget
- Requirement candidate escalation from annotations
- Triage queue and governance lifecycle (Requirement → Decision → Deployment)
- AI-assisted requirement drafting (if AgentRegistration is configured)
- Outcome signals and regression detection
- Widget marketplace discovery

Your hub only needs to POST events. Everything downstream is managed by
inter-hub.

---

## Pattern B — IHP Extension Hub (Haskell)

### Prerequisites

The same build infrastructure used for inter-hub works directly:
- haskelseed VM (`192.168.178.135`) with GHC 9.10.3 in the Nix store
- `devenv` for reproducible environments
- The painful one-time Nix setup is already done — a new IHP project reuses
  the same Nix store

### Bootstrap a new hub repo

```bash
# On your workstation (Nix must be installed)
nix profile install nixpkgs#ihp-new
ihp-new dev-hub
cd dev-hub

# Edit devenv.nix to pin to the same IHP version as inter-hub (1.5.0)
# Then:
devenv up
```

The first `devenv up` on a fresh machine takes 20–40 min to fetch Nix
dependencies. On haskelseed, most dependencies are already in the Nix store
and the setup takes ~2 minutes.

### Connect to inter-hub's API

Add the inter-hub API client to your hub. The simplest approach:

```haskell
-- Application/Helper/InterHubClient.hs
module Application.Helper.InterHubClient where

import IHP.Prelude
import Network.HTTP.Simple

postEvent :: Text -> Text -> Text -> Value -> IO ()
postEvent apiKey widgetId eventType payload = do
    let req = setRequestMethod "POST"
            $ setRequestHeader "Authorization" ["Bearer " <> cs apiKey]
            $ setRequestHeader "Content-Type" ["application/json"]
            $ setRequestBodyJSON (object
                [ "widgetId"  .= widgetId
                , "eventType" .= eventType
                , "payload"   .= payload
                ])
            $ parseRequest_ "http://192.168.178.135:8080/api/v2/interaction-events"
    void $ httpLBS req
```

### Shared database (optional)

If your hub needs read access to inter-hub's tables (e.g., to join against
`requirements` or `decision_records`), connect to the same PostgreSQL:

```bash
# In your hub's .env:
DATABASE_URL=postgresql://ihp:ihp@192.168.178.135/interhub
```

Your IHP app can then use `query @DecisionRecord` directly without going
through the API. This is appropriate for tightly-coupled hubs that are
part of the same operational boundary.

For loosely-coupled hubs (separate teams, separate deploy cadence), use
the API only — do not share the database.

### How fast is the Haskell build for a new hub?

A fresh IHP project with 10 controllers and 20 views compiles to ~150
modules (vs inter-hub's 616). With the Nix store already populated on
haskelseed:

| Stage | Time |
|-------|------|
| First `devenv up` (Nix fetch) | ~2 min (store populated) |
| First GHCi load (150 modules) | ~3–5 min |
| Incremental reload (1 module changed) | ~5–15 s |
| Adding a new controller+view pair | ~10–30 s compile time |

This is practical for active development. The painful build experience with
inter-hub was caused by its scale (616 modules, 12 phases worth of code)
and the Alpine setup being done from scratch. A new hub starts small.

---

## Honest Assessment: Is IHP a Good Framework for Domain Hubs?

**Yes, with caveats.**

**Strengths:**
- Type safety catches integration errors at compile time, not at 2am
- Server-rendered HSX views are fast to write once you know IHP conventions
- The query builder and auto-generated types eliminate a whole class of SQL bugs
- IHP's code generator scaffolds a controller+4 views in seconds
- Once the Nix environment is set up, it is reproducible — no "works on my machine"

**Caveats:**
- The initial Nix setup is still painful on a new machine (~1h)
- GHC error messages for type inference failures are dense
- No hot-reload for Haskell (GHCi restart is fast, but not instant)
- The `hub-core` shared library is planned but not yet implemented —
  each new hub currently duplicates boilerplate for API client setup,
  hub registration, and event posting

**Bottom line:** If you are already comfortable with Haskell and IHP,
building domain hubs in the same stack is efficient and the type safety
pays dividends quickly. If your team is not Haskell-native, Pattern A
(API consumer) is the pragmatic choice — the API surface is stable and
well-documented, and you can add a lightweight web layer in whatever
language fits your team.

---

## What hub-core Would Provide

The planned `hub-core` Haskell library (not yet implemented) would give
every domain hub:

- `HubRegistration` typeclass — register with inter-hub on startup
- `WidgetEnvelope` helpers — consistent widget wrapping across hubs
- `InterHubClient` — typed API client with retry and auth built in
- `HubCapabilityManifest` bootstrap — auto-activate manifest on startup
- Shared `defaultLayout` with inter-hub navigation integration

Until `hub-core` exists, copy the client helper above and the 3-step
registration pattern into your new hub. It is ~50 lines of boilerplate.

---

## Checklist for a New Hub

- [ ] Create ApiConsumer + ApiKey in inter-hub UI
- [ ] Record your hub ID and API key in the new hub's `.env`
- [ ] Register HubCapabilityManifest with domain type vocabulary
- [ ] Activate the manifest (validates no naming conflicts)
- [ ] Create at least one Widget per meaningful UI surface
- [ ] Instrument interactions with POST to `/api/v2/interaction-events`
- [ ] Verify events appear in inter-hub at `/InteractionEvents`
- [ ] (Optional) Configure AgentRegistration and ModelRoutingPolicy for
      AI-assisted requirement drafting
- [ ] (Optional) Set up HubRoutingRules to route annotations to your hub's
      triage queue

---

## Reference

| Resource | Location |
|----------|----------|
| API reference (OpenAPI) | `http://192.168.178.135:8080/api/v2/openapi.json` |
| Type registry browser | `http://192.168.178.135:8080/TypeRegistries/WidgetTypes` |
| Domain hub extension guide | `docs/domain-hub-extension-guide.md` |
| IHP data and queries | `docs/ihp-data-and-queries.md` |
| IHP controllers and views | `docs/ihp-controllers-views-forms.md` |
| Functional module maturity | `docs/functional-modules.md` |
| IHF v0.2 specification | `specs/InteractionHubFrameworkSpecification_v0.2.md` |