# Nova Retail Context Delta

> Nova Retail Context Delta is a paid API for AI agents from nova-retail-controlled-proof.onrender.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-11).

Submits a context delta update for a retail session, capturing incremental state changes in a retail context resource

## Facts

- Endpoint: POST https://nova-retail-controlled-proof.onrender.com/retail/v1/context/context-delta?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/nova-retail-context-delta-dffe75a1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_np3192RGRAC9urCQaOoUA

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability nova-retail-context-delta-dffe75a1 -d '<json body>'
```

Example prompt: Push a context delta update to the Nova retail context service for our current retail session — the cart quantity changed from 2 to 5 and the selected SKU is 'SHOE-RED-42'.

## When to prefer this

Choose this endpoint when you need to submit incremental, differential state changes to a retail context resource rather than replacing the full state. It is suited for event-driven retail workflows where only changed fields need to be pushed, keeping payloads small and efficient.

## Known failure modes

- Invalid or missing context delta payload returns a 400 error
- Session or context identifier not found returns a 404
- Payment not included or invalid x402 payment header returns a 402
- Malformed delta structure results in rejection
- Service unavailable on Render cold start returns a 503

## How this service works

Nova retail context_delta context resource

## Output

Returns an acknowledgment confirming the context delta was received and applied, along with the updated context state or a confirmation identifier for the delta event.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "subject": {
   "label": "BTC/USD",
   "subject_id": "BTC-USD",
   "subject_type": "market_pair"
  },
  "limitations": [],
  "resource_id": "context-delta-91e9a7267ab3fcdce8fe8f66",
  "delta_status": "changed",
  "generated_at": "2026-09-12T12:00:00Z",
  "resource_type": "context_delta",
  "schema_version": "0.1.0",
  "authority_effect": "none",
  "material_changes": [
   {
    "field": "observed_at",
    "item_id": null,
    "category": "freshness",
    "change_id": "material-change-aad59f135d32b8e6cfb9f8e3",
    "change_type": "value_changed",
    "current_value": "2026-09-12T12:00:00Z",
    "previous_value": "2026-09-12T11:55:00Z"
   },
   {
    "field": "observed_at",
    "item_id": "public-example-source",
    "category": "provenance",
    "change_id": "material-change-ee1ca54c09fa66775144e3a4",
    "change_type": "value_changed",
    "current_value": "2026-09-12T12:00:00Z",
    "previous_value": "2026-09-12T11:55:00Z"
   },
   {
    "field": "content",
    "item_id": "public-example-last-price",
    "category": "evidence",
    "change_id": "material-change-f712bc18f08980ebc25df088",
    "change_type": "content_changed",
    "current_value": "{\"claim_or_observation\":\"last_price=100100 BTC-USD\",\"evidence_id\":\"public-example-last-price\",\"source_id\":\"public-example-source\"}",
    "previous_value": "{\"claim_or_observation\":\"last_price=100000 BTC-USD\",\"evidence_id\":\"public-example-last-price\",\"source_id\":\"public-example-source\"}"
   }
  ],
  "freshness_changes": [
   {
    "field": "observed_at",
    "change_id": "freshness-change-ebecda1fcbfb3c08e114de17",
    "current_value": "2026-09-12T12:00:00Z",
    "previous_value": "2026-09-12T11:55:00Z"
   }
  ],
  "confidence_changes": [],
  "current_context_id": "state-ping-example-current",
  "limitation_changes": [],
  "provenance_changes": [
   {
    "field": "observed_at",
    "change_id": "provenance-change-c14455d3e5b633ef90196215",
    "source_id": "public-example-source",
    "change_type": "observed_at_changed",
    "current_value": "2026-09-12T12:00:00Z",
    "previous_value": "2026-09-12T11:55:00Z"
   }
  ],
  "previous_context_id": "state-ping-example-previous",
  "contradiction_changes": [],
  "evidence_state_changes": [
   {
    "change_id": "evidence-change-d18b1a54a0b68c6855212169",
    "source_id": "public-example-source",
    "change_type": "content_changed",
    "evidence_id": "public-example-last-price",
    "current_status": "observe
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/nova-retail-context-delta-dffe75a1/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from nova-retail-controlled-proof.onrender.com](https://www.zero.xyz/host/nova-retail-controlled-proof.onrender.com/llms.txt)