# UI, Query API, and Schema Validation Design

Date: 2026-01-17

## Overview

This design covers three related improvements to agentmon:

1. **Web UI** — Sessions list, session detail, and run detail views
2. **Query API** — New endpoints to support the UI
3. **Schema Validation** — Required field validation at ingest-gateway

## URL Structure

| URL | View | Description |
|-----|------|-------------|
| `/` | Redirect | Redirects to `/sessions` |
| `/sessions` | Sessions List | Recent sessions, filterable |
| `/sessions/:session_id` | Session Detail | Runs within a session |
| `/runs/:run_id` | Run Detail | Spans within a run |

Query parameters for filtering:

- `/sessions?from=2026-01-17&to=2026-01-18` — time range
- `/sessions?framework=opencode` — filter by framework
- `/sessions?host=willlaptop` — filter by host
- Parameters combine: `/sessions?framework=claude-code&host=willlaptop`

## Query API Endpoints

### GET /v1/sessions

List sessions with filters.

Query params:

- `from`, `to` — ISO timestamps (default: last 24h)
- `framework` — filter by source framework
- `host` — filter by source host
- `limit` — max results (default 50, max 200)
- `cursor` — pagination token (opaque, timestamp-based)

Response:

```json
{
  "sessions": [
    {
      "session_id": "s1",
      "started_at": "2026-01-17T08:00:00Z",
      "ended_at": "2026-01-17T09:30:00Z",
      "framework": "claude-code",
      "host": "willlaptop",
      "run_count": 5
    }
  ],
  "next_cursor": "..."
}
```

### GET /v1/sessions/:session_id

Session detail with runs.

Response:

```json
{
  "session": {
    "session_id": "...",
    "started_at": "...",
    "ended_at": "...",
    "framework": "...",
    "host": "..."
  },
  "runs": [
    {
      "run_id": "r1",
      "started_at": "...",
      "ended_at": "...",
      "status": "success",
      "span_count": 12
    }
  ]
}
```

### GET /v1/runs/:run_id

Run detail with spans.

Response:

```json
{
  "run": {
    "run_id": "...",
    "session_id": "...",
    "started_at": "...",
    "ended_at": "...",
    "status": "..."
  },
  "spans": [
    {
      "span_id": "sp1",
      "name": "Bash",
      "kind": "tool",
      "started_at": "...",
      "duration_ms": 1234,
      "status": "success",
      "payload": {}
    }
  ]
}
```

## UI Views

### Sessions List

Default view showing last 24 hours, most recent first.

Layout:

- Filter bar: time range (from/to), framework dropdown, host dropdown
- Table columns: Session ID, Framework, Host, Run Count, Time (relative)
- Click row to navigate to session detail
- "Load more" button for pagination

### Session Detail

Shows session metadata and all runs within it.

Layout:

- Header: Session ID, framework, host, start time, total duration
- Back link to sessions list
- Runs table: Run ID, Status, Span Count, Duration, Start Time
- Click row to navigate to run detail

Status indicators:

- Green checkmark for success
- Red X for error
- Yellow circle for running/unknown

### Run Detail

Shows run metadata and all spans within it.

Layout:

- Header: Run ID, status, start time, duration
- Back link to session detail
- Spans table: Name, Kind, Status, Duration
- Click row to expand/collapse details

Expanded span shows:

- Model name, tokens, cost (for LLM spans)
- Error details (for failed spans)
- Raw payload JSON

## Schema Validation

Validation performed at ingest-gateway before publishing to NATS.

### Required Fields

All events must include:

```
schema.name          = "agentmon.event"
schema.version       = 1
event.id             — non-empty string
event.type           — one of: session.start, session.end, run.start,
                       run.end, span.start, span.end, error, metric.snapshot
event.ts             — valid timestamp (RFC3339 or unix-ms)
event.source.framework   — non-empty string
event.source.client_id   — non-empty string
event.source.host        — non-empty string
```

### Validation Responses

| Scenario | HTTP | WebSocket |
|----------|------|-----------|
| Valid | 202 Accepted | `{"ack": {"seq": N}}` |
| Missing field | 400 + error | `{"error": "missing_field", "field": "..."}` |
| Invalid type | 400 + error | `{"error": "invalid_type", "value": "..."}` |
| Unknown fields | Allow | Allow |

Non-strict mode: unknown fields in `correlation`, `attributes`, and `payload` are stored as-is.

## Frontend Implementation

Technology: Vanilla JavaScript (no framework, no build step).

File structure:

```
cmd/web-ui/static/
├── index.html      # Shell + router
├── app.js          # Router + page loader
├── pages/
│   ├── sessions.js
│   ├── session.js
│   └── run.js
└── style.css
```

Routing: History API with catch-all handler serving index.html for all routes.

Data fetching: Native fetch() to query-api endpoints via /api proxy.

## Implementation Order

1. Query API endpoints (sessions, session detail, run detail)
2. Schema validation at ingest-gateway
3. Frontend pages (sessions list, session detail, run detail)
4. Rebuild and deploy

## Future Considerations

- Waterfall visualization for spans (SVG/canvas)
- Token/cost aggregations in session/run summaries
- Free-text search across sessions
- Real-time updates via WebSocket subscription