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

# Add Liquidity

> Deposit the borrow asset into the pool and receive LP shares

Deposits the market's borrow asset into the lending pool. The depositor receives LP shares proportional to their contribution, and those shares accrue value as borrowers pay interest.

Two transactions are required: an ERC-20 approval, then the deposit. Both come back as ordered steps.

## Path Parameters

<ParamField path="marketId" type="string" required>Market ID.</ParamField>

## Body Parameters

<ParamField body="amount" type="string" required>
  Amount to deposit as a decimal string, for example `"250000"`. Denominated in the market's borrow asset and parsed at its decimals.
</ParamField>

<ParamField body="provider" type="string">
  Wallet that will sign the deposit. When supplied, the API checks it against the market's identity registry before offering a transaction and refuses with `IDENTITY_NOT_VERIFIED` if it would be rejected on-chain. Omit it to skip that check.
</ParamField>

<ParamField body="txHash" type="string">
  Hash of the transaction you broadcast for this operation. Send it to confirm the transaction and record the result. Omit it to receive the calldata.
</ParamField>

## Response Fields

<ResponseField name="data" type="object">
  <Expandable>
    <ResponseField name="action" type="string">`SIGN_TRANSACTIONS` when `txHash` is omitted.</ResponseField>
    <ResponseField name="steps" type="array">Ordered transactions to broadcast. Returned when `txHash` is omitted. The first approves the market to pull the borrow asset, the second calls `addLiquidity`.</ResponseField>
    <ResponseField name="confirmStepIndex" type="integer">Index of the step to confirm with. Always `1`.</ResponseField>
    <ResponseField name="confirmWith" type="string">`addLiquidity`.</ResponseField>
    <ResponseField name="txHash" type="string">Deposit transaction hash. Returned when confirming with `txHash`.</ResponseField>
    <ResponseField name="amount" type="string">Amount actually deposited, read from the `LiquidityAdded` event rather than from the request. Returned when confirming with `txHash`.</ResponseField>
  </Expandable>
</ResponseField>

<Info>
  The first deposit into an empty pool must be at least 1,000,000,000 base units of the borrow asset. That is 1,000 USDC or USDT for a 6-decimal asset. The floor exists to prevent share price manipulation against an empty pool. Subsequent deposits have no minimum beyond the token's own precision.
</Info>

<Warning>
  The minimum deposit is checked when the calldata is built, not when you confirm. Broadcasting an undersized first deposit reverts on-chain rather than returning `BELOW_MIN_DEPOSIT`. Check the pool's `totalShares` through [Get Market Metrics](/endpoints/lending/get-metrics) if you need to detect an empty pool ahead of time.
</Warning>

<Note>
  Depositors receive shares at the current share price, which already includes accrued interest. Depositing does not dilute existing providers.
</Note>

<RequestExample>
  ```bash cURL theme={null}
  curl -X POST "https://api.trusset.org/lending-external-securities/api/positions/{marketId}/add-liquidity" \
    -H "X-API-Key: trusset_your_key_here" \
    -H "Content-Type: application/json" \
    -d '{"amount": "250000"}'
  ```

  ```typescript TypeScript theme={null}
  const res = await fetch(
    `https://api.trusset.org/lending-external-securities/api/positions/${marketId}/add-liquidity`,
    {
      method: 'POST',
      headers: {
        'X-API-Key': 'trusset_your_key_here',
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({ amount: '250000' })
    }
  );
  const { data } = await res.json();

  for (const step of data.steps) {
    const tx = await wallet.sendTransaction(step.transaction);
    await tx.wait();
  }
  ```
</RequestExample>

<ResponseExample>
  ```json Calldata Response theme={null}
  {
    "success": true,
    "data": {
      "action": "SIGN_TRANSACTIONS",
      "steps": [
        {
          "action": "SIGN_TRANSACTION",
          "transaction": {
            "to": "0x98ad0ca091552e23c564b41c74282e5343d03e8a",
            "data": "0x...",
            "value": "0",
            "chainId": 11155111
          },
          "functionName": "approve",
          "description": "Approve the market to pull USDC"
        },
        {
          "action": "SIGN_TRANSACTION",
          "transaction": {
            "to": "0x70a0e25c7b768b87e658348b3b577678a173e038",
            "data": "0x...",
            "value": "0",
            "chainId": 11155111
          },
          "functionName": "addLiquidity"
        }
      ],
      "confirmStepIndex": 1,
      "confirmWith": "addLiquidity"
    }
  }
  ```

  ```json Confirmed Response theme={null}
  {
    "success": true,
    "data": {
      "txHash": "0x9f2c41d8b7e05a3164c2870fbd935e1a4c7802db6135ea9048f7c21b5d3ea41b",
      "amount": "250000.000000"
    }
  }
  ```

  ```json Error - Below Minimum theme={null}
  {
    "success": false,
    "error": {
      "code": "BELOW_MIN_DEPOSIT",
      "message": "The first deposit into a market must be at least 1000000000 of the smallest USDC unit (1000.0 USDC at 6 decimals)."
    }
  }
  ```
</ResponseExample>

## Error Codes

| Code                       | HTTP  | Cause                                                                                                            |
| -------------------------- | ----- | ---------------------------------------------------------------------------------------------------------------- |
| `NO_MARKET_ADDRESS`        | `400` | The market has no on-chain address recorded                                                                      |
| `VALIDATION_ERROR`         | `400` | `amount` is not a positive decimal string, or carries more decimal places than the borrow asset supports         |
| `BELOW_MIN_DEPOSIT`        | `400` | This is the first deposit into an empty pool and it is under the floor                                           |
| `MARKET_PAUSED`            | `400` | The market is paused. Its admin must unpause it                                                                  |
| `IDENTITY_NOT_VERIFIED`    | `400` | `provider` is not verified on the market's identity registry                                                     |
| `MARKET_NOT_FOUND`         | `404` | No market with this ID on your instance                                                                          |
| `MARKET_PENDING_CURATOR`   | `409` | The market has no lender of record yet. See [Lender of record](/endpoints/lending/introduction#lender-of-record) |
| `MARKET_STATE_UNAVAILABLE` | `503` | The market could not be read to check the first-deposit minimum. Retry shortly                                   |