{
  "id": "br1-bridge-base",
  "title": "The L2 Bridge",
  "extends": "m1-send-metamask",
  "context": {
    "wallet": "MetaMask extension",
    "platform": "Chrome extension",
    "network": "mainnet → Base",
    "settings": "defaults",
    "version": "web/5.157.3",
    "observed": "2026-08-26",
    "captures": [
      {
        "run": "20260826-185312-bridge-metamask",
        "note": "dry — driven to the quoted Ethereum→Base bridge screen (ETH→ETH on Base), not broadcast"
      }
    ]
  },
  "_comment": "Moving ETH from Ethereum to an L2 (Base). MetaMask merged Bridge INTO Swap — same closed engine, bridge.api.cx.metamask.io/getQuoteStream, now computing a CROSS-CHAIN route (observed: 0.002 ETH → 0.00198 ETH on Base, rate ~0.991, 0.875% MetaMask fee). The convenient bridge stacks NEW trust beyond a same-chain send: (1) MetaMask's closed quote engine picks the route and the bridge provider you can't see; (2) whatever bridge/relayer that route uses becomes a party that can stall or censor the transfer; (3) you enter Base — Coinbase's L2 — whose sequencer now orders your transactions. THE ZERO-OPTION POINT (Yoav, Aug 25): this convenient path is NOT the escape hatch. The self-sovereign way off an L2 is the FORCED L1 EXIT — submitting your withdrawal directly through the L1 rollup contract without the sequencer's cooperation (Base/OP via the portal's forced inclusion; Arbitrum via the delayed inbox). Slow, painful, technical — but operator-independent. Success there is BINARY: either you can load an exit UI from IPFS and force your way out, or you can't. This map draws the convenient path (observed); the forced exit is the missing zero option.",
  "prepend_steps": [
    {
      "id": "bridge-quote",
      "phase": "discover",
      "name": "MetaMask bridge engine · route + provider",
      "host": "bridge.api.cx.metamask.io/getQuoteStream",
      "actor": "consensys-apis",
      "purpose": "One streamed call returns the cross-chain route, which bridge provider carries it, the minimum received, and the 0.875% fee",
      "need": "RC",
      "carries": [
        "ip",
        "selected_address",
        "amount",
        "holdings",
        "chain_id"
      ],
      "births": [
        "unsigned_tx",
        "swap_route"
      ],
      "returns": "the route + the bridge operator you'll trust to carry your funds across",
      "can_block": true,
      "on_failure": "blocks",
      "failure_note": "no quote → no bridge; no second route source in the UI",
      "worst_lie": {
        "outcome": "funds_lost",
        "note": "one closed API picks the bridge provider and the minimum-out; a bad route or a bridge that stalls can strand or lose funds mid-transfer"
      },
      "removable_by": "none",
      "tx_input": "field",
      "provenance": {
        "status": "observed",
        "ref": "20260826-185312-bridge-metamask · GET bridge.api.cx.metamask.io/getQuoteStream"
      },
      "notes": "Same engine as the M4 swap — MetaMask unified Swap + Bridge. The bridge provider it routes through is not shown to the user.",
      "fixed_by": [
        "cr-broadcast",
        "verifiable-rpc"
      ]
    },
    {
      "id": "l2-read",
      "phase": "discover",
      "name": "Infura · Base L2 state",
      "host": "base-mainnet.infura.io",
      "actor": "infura",
      "purpose": "Read Base (the destination L2) — balances and state on the chain you're bridging into",
      "need": "R",
      "carries": [
        "ip",
        "selected_address",
        "chain_id"
      ],
      "returns": "destination-chain state",
      "can_block": true,
      "on_failure": "degrade",
      "worst_lie": {
        "outcome": "false_belief",
        "note": "the same RPC company now also sees you on the L2 — your activity on both chains links to one IP + address"
      },
      "removable_by": "none",
      "provenance": {
        "status": "observed",
        "ref": "20260826-185312-bridge-metamask · base-mainnet.infura.io"
      },
      "notes": "Bridging doesn't escape the RPC dependency — it doubles it (mainnet + the L2), under the same company.",
      "fixed_by": [
        "verifiable-rpc",
        "private-rpc"
      ]
    }
  ],
  "own_node": {
    "node": "192.168.68.54",
    "runs": [
      "20260924-214322-bridge-metamask-localnode"
    ],
    "steps": {
      "bridge-quote": {
        "state": "out",
        "ref": "bridge.api.cx.metamask.io · 4 req after switch · /getquotestream"
      },
      "l2-read": {
        "state": "out",
        "ref": "base-mainnet.infura.io · 2 req after switch"
      },
      "ext-update": {
        "state": "unseen",
        "ref": "clients2.google.com seen before the switch only, not after"
      },
      "feature-flags": {
        "state": "out",
        "ref": "client-config.api.cx.metamask.io · 1 req after switch"
      },
      "phishing-list": {
        "state": "unseen",
        "ref": "phishing-detection.api.cx.metamask.io seen before the switch only, not after"
      },
      "c2-list": {
        "state": "unseen",
        "ref": "client-side-detection.api.cx.metamask.io seen before the switch only, not after"
      },
      "token-list": {
        "state": "out",
        "ref": "token.api.cx.metamask.io · 2 req after switch"
      },
      "spot-prices": {
        "state": "out",
        "ref": "price.api.cx.metamask.io · 6 req after switch · /v3/spot-prices"
      },
      "fiat-rates": {
        "state": "unseen",
        "ref": "price.api.cx.metamask.io still contacted (6 req) but this exact call wasn't singled out"
      },
      "accounts-balances": {
        "state": "out",
        "ref": "accounts.api.cx.metamask.io · 3 req after switch · /v4/multiaccount/balances"
      },
      "balance-fallback": {
        "state": "local",
        "ref": "192.168.68.54 · eth_call; mainnet.infura.io got 0 after switch"
      },
      "nft-detection": {
        "state": "unseen",
        "ref": "nft.api.cx.metamask.io seen before the switch only, not after"
      },
      "defi-positions": {
        "state": "unseen",
        "ref": "defiadapters.api.cx.metamask.io seen before the switch only, not after"
      },
      "icons": {
        "state": "out",
        "ref": "static.cx.metamask.io · 28 req after switch"
      },
      "block-poll": {
        "state": "local",
        "ref": "192.168.68.54 · eth_blockNumber; mainnet.infura.io got 0 after switch"
      },
      "segment": {
        "state": "out",
        "ref": "api.segment.io · 6 req after switch"
      },
      "sentry": {
        "state": "out",
        "ref": "sentry.io · 13 req after switch"
      },
      "screen-recipient": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "nonce": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "gas-fees": {
        "state": "out",
        "ref": "gas.api.cx.metamask.io · 4 req after switch · suggestedgasfees"
      },
      "estimate-gas": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "simulation": {
        "state": "out",
        "ref": "tx-sentinel-ethereum-mainnet.api.cx.metamask.io · 2 req after switch"
      },
      "security-alert": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "stx-broadcast": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "inclusion": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "stx-status": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "receipt-poll": {
        "state": "unseen",
        "ref": "mainnet.infura.io seen before the switch only, not after"
      },
      "etherscan-check": {
        "state": "unseen",
        "ref": "not in these runs"
      },
      "balance-refresh": {
        "state": "unseen",
        "ref": "accounts.api.cx.metamask.io still contacted (3 req) but this exact call wasn't singled out"
      }
    },
    "unmapped": [
      "tron-mainnet.infura.io",
      "solana-mainnet.infura.io",
      "bitcoin-mainnet.infura.io",
      "user-storage.api.cx.metamask.io",
      "monad-mainnet.infura.io",
      "subscription.api.cx.metamask.io",
      "api.merkl.xyz",
      "bsc-mainnet.infura.io",
      "optimism-mainnet.infura.io",
      "polygon-mainnet.infura.io",
      "arbitrum-mainnet.infura.io",
      "linea-mainnet.infura.io",
      "carrot.megaeth.com",
      "sepolia.infura.io",
      "testnet-rpc.monad.xyz",
      "linea-sepolia.infura.io",
      "notification.api.cx.metamask.io",
      "geolocation.api.cx.metamask.io",
      "on-ramp-cache.api.cx.metamask.io",
      "tokens.api.cx.metamask.io",
      "authentication.api.cx.metamask.io",
      "metamask.github.io",
      "cdn.contentful.com",
      "gateway.api.cx.metamask.io"
    ]
  }
}