# On-Ramp and Off-Ramp User Flows (Mainnet ↔ Chain 138)

**Purpose:** Document the recommended user flows for fiat on-ramp and off-ramp when using mainnet liquidity and third-party bridges. Companion/dApp copy and links should point here.

**Related:** [MAINNET_LIQUIDITY_AND_RAMPS_PRIORITY](../00-meta/MAINNET_LIQUIDITY_AND_RAMPS_PRIORITY.md) | [METAMASK_BRIDGE_SWAP](../../smom-dbis-138/docs/operations/integrations/METAMASK_BRIDGE_SWAP.md)

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## On-ramp (Fiat → Crypto on Chain 138)

**Flow:** User buys on a supported chain (e.g. Ethereum Mainnet) via ramp, then bridges to Chain 138.

| Step | User action |
|------|-------------|
| 1 | Open companion/dApp and choose **Buy** (on-ramp). |
| 2 | Select **Ethereum Mainnet** (or another ramp-supported chain). Complete purchase via ramp provider (MoonPay, Ramp, etc.) — funds arrive on mainnet. |
| 3 | Switch to **Bridge** and send assets **Mainnet → Chain 138** using a supported bridge (trustless or third-party). |
| 4 | Receive assets on Chain 138; use for gas, swaps, or dApps. |

**Operator:** Ensure ramp API keys are set and mainnet is funded so bridges can operate. Ramp API: `POST /ramps/on-ramp/session` with `chainId: 1`.

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## Off-ramp (Crypto on Chain 138 → Fiat)

**Flow:** User bridges from Chain 138 to Mainnet, then sells on mainnet via off-ramp.

| Step | User action |
|------|-------------|
| 1 | On Chain 138, open **Bridge** and send assets **Chain 138 → Ethereum Mainnet**. |
| 2 | Wait for bridge confirmation; assets arrive on user’s mainnet address. |
| 3 | Open companion/dApp and choose **Sell** (off-ramp). Select **Ethereum Mainnet** and complete sale via ramp provider. |
| 4 | Fiat is sent to user’s linked bank/payment method per provider terms. |

**Operator:** Mainnet liquidity (LiquidityPoolETH and/or Relay Bridge) must be funded so 138→mainnet payouts succeed. Ramp API: `POST /ramps/off-ramp/session` with `chainId: 1`.

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## Where to link in companion/dApp

- **Buy (on-ramp):** Link to this doc or a short in-app guide: “Buy on Ethereum → Bridge to Chain 138.”
- **Sell (off-ramp):** Link to this doc or a short in-app guide: “Bridge to Ethereum → Sell on mainnet.”