> ## Documentation Index
> Fetch the complete documentation index at: https://docs.interchange.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Apply proposal

> Accept a seller proposal's full budget allocation in one call

`POST /api/v2/buyer/discovery/{discoveryId}/apply-proposal`

Applies a seller proposal returned by [Discover products](/v2/buyer/discovery/tasks/discover-products), auto-adding its products with the proposal's recommended budget allocations. Requires discover-products to have run first so the proposal's products are in the session cache. Defaults the distributed budget to `proposal.totalBudgetGuidance.recommended`; set `replace: true` to clear the existing selection before applying.

## Request

```bash theme={null}
curl -X POST https://api.interchange.io/api/v2/buyer/discovery/disc_01HZX3YQ7K9R6V3M2P1E0F8B2T/apply-proposal \
  -H "Authorization: Bearer $SCOPE3_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "proposalId": "proposal_acme_q3_sports",
    "totalBudget": 250000,
    "replace": true
  }'
```

## Parameters

| Field         | Type    | Required | Notes                                                                               |
| ------------- | ------- | -------- | ----------------------------------------------------------------------------------- |
| `discoveryId` | string  | Yes      | Path param — session to apply into                                                  |
| `proposalId`  | string  | Yes      | Proposal ID from the discover-products response                                     |
| `totalBudget` | number  | No       | Budget to distribute across products. Defaults to `totalBudgetGuidance.recommended` |
| `replace`     | boolean | No       | When `true`, clears existing selected products before applying                      |

## Response

```json theme={null}
{
  "discoveryId": "disc_01HZX3YQ7K9R6V3M2P1E0F8B2T",
  "proposal": {
    "proposalId": "proposal_acme_q3_sports",
    "name": "Q3 Sports - premium CTV mix",
    "salesAgentName": "Acme Media Ad Sales"
  },
  "totalBudgetUsed": 250000,
  "productsApplied": 2,
  "productsSkipped": [],
  "products": [
    {
      "productId": "prod_acme_ctv_sports",
      "salesAgentId": "agent_acme_media",
      "bidPrice": 32.5,
      "budget": 150000,
      "groupId": "ctx_disc_01HZX3-group-0",
      "groupName": "Acme Media Connected TV",
      "selectedAt": "2026-06-07T15:04:00Z"
    }
  ],
  "totalProducts": 2,
  "budgetContext": { "sessionBudget": 250000, "allocatedBudget": 250000, "remainingBudget": 0 }
}
```

`productsSkipped` is non-empty when a proposal references a product that has aged out of the cached discovery results. Re-run discover to refresh the session, then re-apply.

## Errors

* `400 VALIDATION_ERROR` — missing `proposalId`, non-positive `totalBudget`, or discover-products was never run for this session.
* `404 NOT_FOUND` — `discoveryId` or `proposalId` not found for the authenticated account.

See [Errors](/v2/reference/errors) for the full error contract.

## Related

<CardGroup cols={2}>
  <Card title="Discovery overview" href="/v2/guides/discovery" icon="rocket">
    Proposals and refinement
  </Card>

  <Card title="Discover products" href="/v2/buyer/discovery/tasks/discover-products" icon="magnifying-glass">
    Surface proposals to apply
  </Card>

  <Card title="Get products" href="/v2/buyer/discovery/tasks/get-products" icon="list">
    Inspect the resulting selection
  </Card>

  <Card title="Add products" href="/v2/buyer/discovery/tasks/add-products" icon="plus">
    Add products one at a time instead
  </Card>
</CardGroup>