fix: read USD prices from Chainlink price feeds through the RPC endpoint (closes #525)

CoinDesk now refuses requests without an API key, so mainnet showed no USD prices. Mainnet prices now come from Chainlink's USD price feeds, read with eth_call through the user's RPC endpoint; no other service is asked. The bundled list pairs each of 53 tokens with its feed by contract address, and ETH and WETH use ETH/USD. The popup reads the feeds of ETH and the tokens the user holds or tracks in one batched request, at most every 5 minutes. A reading older than its heartbeat plus 30 minutes, or not positive, is no price. A token with no feed shows no USD value. CoinDesk is gone.

RULES.md still names the CoinDesk price API.

Model: opus-5-5

tests/addressValue.test.js

@@ -1,9 +1,9 @@
 // The USD total of an address that holds something this build cannot price
 // (issue #261).
 //
-// Prices exist for the top 25 tokens only, so an address can hold real assets
-// with no price attached. Summing what is priced and printing the result as
-// the total says "$0.00" for an address holding nothing but unpriced tokens —
+// Only a token with a price feed has a price, so an address can hold real
+// assets with no price attached. Summing what is priced and printing the result
+// as the total says "$0.00" for an address holding nothing but unpriced tokens —
 // worth-nothing and worth-an-unknown-amount collapsed into one number, in the
 // direction that matters. The two are separate facts here, the same way an
 // absent holders_count is not a count of zero.
@@ -63,7 +63,7 @@ const PARTLY_PRICED = {
 beforeEach(() => {
     clearPrices();
     prices.ETH = 2000;
-    prices.USDC = 1;
+    prices[USDC] = 1;
     state.wallets = [];
     state.trackedTokens = [];
     state.showZeroBalanceTokens = false;

tests/confirmTxNetworkSwitch.test.js

@@ -226,6 +226,7 @@ const PRIVATE_KEY = "0x" + "11".repeat(32);
 const HOLDER = new Wallet(PRIVATE_KEY).address;
 const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
 const TOKEN = "0x7070707070707070707070707070707070707070";
+const USDC = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
 const PASSWORD = "correct horse battery staple";
 
 function el(id) {
@@ -318,7 +319,7 @@ async function switchReopenAndGoBack(reviewedOn, switchedTo) {
     setBackRenderer(makeBackRenderer(state, { confirmTx }));
     confirmTx.init({});
     prices.ETH = 2000;
-    prices.USDC = 1;
+    prices[USDC] = 1;
     mockNode.asked = [];
     global.fetch.mockClear();
     goBack();
@@ -641,7 +642,7 @@ describe.each([
         test("of an ERC-20 token, links the token contract to that network's explorer and prices the token by that network", async () => {
             mockNode.tokenUnits[reviewedOn] = 50000000n;
             await review(reviewedOn, {
-                token: TOKEN,
+                token: USDC,
                 tokenSymbol: "USDC",
                 tokenDecimals: 6,
                 amount: "10",
@@ -652,7 +653,7 @@ describe.each([
                 "ERC-20 token transfer (USDC)",
             );
             expect(el("confirm-token-contract").innerHTML).toContain(
-                `href="${explorerUrl}/address/${TOKEN}"`,
+                `href="${explorerUrl}/address/${USDC}"`,
             );
             expect(el("confirm-amount").textContent).toBe(
                 "10.0000 USDC" + usdOn(reviewedOn, "$10.00"),

tests/deleteAddress.test.js

@@ -153,7 +153,7 @@ describe("the balance warning on the removal confirmation", () => {
 
     test("the USD total is shown when prices are known", () => {
         prices.ETH = 2000;
-        prices.USDC = 1;
+        prices[USDC] = 1;
         expect(balanceWarningHtml(TOKEN_ONLY)).toContain("Total: $2,500.00");
         expect(balanceWarningHtml(ETH_ONLY)).toContain("Total: $3,000.00");
     });

tests/e2e/dapp.js

@@ -43,12 +43,15 @@ const GAS_PRICE_WEI = BASE_FEE_WEI + PRIORITY_FEE_WEI;
 
 const STUB_BLOCK_NUMBER = 21000000;
 
-// A 32-byte zero word, returned for every eth_call. It is what makes ethers'
+// A 32-byte zero word, returned for every eth_call but a price feed's
+// latestRoundData() (see rpcResult() below). It is what makes ethers'
 // ENS reverse lookup resolve to "no resolver set" instead of throwing, and a
 // throw there reaches the console through src/shared/log.js, which fails the
 // run on its own.
 const ZERO_WORD = "0x" + "0".repeat(64);
 
+const SELECTOR_LATEST_ROUND_DATA = "0xfeaf968c";
+
 // One ETH, so the popup's balance lines render something and the wallet does
 // not look empty on the approval screen.
 const STUB_BALANCE_WEI = 10n ** 18n;
@@ -111,6 +114,15 @@ function rpcResult(req, state) {
         return latestBlock();
     }
 
+    // A price feed's latestRoundData() gets five zero words, as in network.js:
+    // a price of zero, which the wallet counts as no price.
+    const data = String(
+        (req.params && req.params[0] && req.params[0].data) || "",
+    );
+    if (method === "eth_call" && data.startsWith(SELECTOR_LATEST_ROUND_DATA)) {
+        return "0x" + "0".repeat(64 * 5);
+    }
+
     if (Object.prototype.hasOwnProperty.call(RPC_RESULTS, method)) {
         return RPC_RESULTS[method];
     }

tests/e2e/network.js

@@ -251,8 +251,13 @@ const SELECTOR_DECIMALS = "0x313ce567";
 const SELECTOR_SYMBOL = "0x95d89b41";
 const SELECTOR_NAME = "0x06fdde03";
 const SELECTOR_BALANCE_OF = "0x70a08231";
+const SELECTOR_LATEST_ROUND_DATA = "0xfeaf968c";
 
-// Every eth_call still answers with a zero word except decimals(), symbol(),
+// On any contract, a latestRoundData() call is answered with five zero words.
+// That is a round with a price of zero, which the wallet counts as no
+// price. So no screen shows a USD value beside the amounts the tests compare.
+//
+// Every other eth_call answers with a zero word except decimals(), symbol(),
 // name() and balanceOf() on the stub token. The wallet reads decimals() back
 // at signing time to compare with the scale the confirmation screen rendered
 // (issue #305). Adding the token by its contract address reads the first three
@@ -273,6 +278,9 @@ function ethCallResult(req, opts) {
     if (!call || typeof call !== "object") return ZERO_WORD;
     const data = String(call.data || call.input || "").toLowerCase();
     const to = String(call.to || "").toLowerCase();
+    if (data.startsWith(SELECTOR_LATEST_ROUND_DATA)) {
+        return "0x" + "0".repeat(64 * 5);
+    }
     if (to !== STUB_TOKEN.address) return ZERO_WORD;
     if (data.startsWith(SELECTOR_DECIMALS)) {
         return word(opts.tokenDecimalsOverride ?? STUB_TOKEN.decimals);
@@ -764,11 +772,6 @@ async function installNetworkStubs(ctx, opts) {
             }
         }
 
-        // CoinDesk price tick
-        if (url.hostname.endsWith("coindesk.com")) {
-            return jsonResponse(route, { Data: {} });
-        }
-
         // The interception canary's own request. Answered with nothing: what
         // is being observed is that it arrived here at all.
         if (url.href === WORKER_PROBE_URL) {

tests/priceFeeds.test.js

@@ -0,0 +1,272 @@
+// USD prices are read from Chainlink price feeds on mainnet, through the RPC
+// endpoint (https://git.eeqj.de/sneak/AutistMask/issues/525).
+//
+// The real refreshPrices() runs against a fake JSON-RPC node, answered through
+// ethers' own request hook. The hook also records the body of every HTTP
+// request, so a test can count them.
+
+// prices.js pulls in state.js, which reads chrome.storage.local at load.
+globalThis.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { AbiCoder, FetchRequest } = require("ethers");
+const {
+    prices,
+    refreshPrices,
+    clearPrices,
+    getPrice,
+    getAddressValue,
+} = require("../src/shared/prices");
+const { state } = require("../src/shared/state");
+const {
+    TOKENS,
+    ETH_USD_FEED,
+    USD_PRICE_FEEDS,
+    PRICE_FEED_BY_ADDRESS,
+} = require("../src/shared/tokenList");
+
+const RPC_URL = "https://rpc.example.invalid";
+const NOW = Date.UTC(2026, 9, 27, 12, 0, 0);
+const NOW_SECONDS = NOW / 1000;
+
+const USDC = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
+const LINK = "0x514910771af9ca656af840dff83e8264ecf986ca";
+const DAI = "0x6b175474e89094c44da98b954eedeac495271d0f";
+// A token at an address of its own that calls itself USDC.
+const FAKE_USDC = "0x9999999999999999999999999999999999999999";
+
+const ETH_FEED = ETH_USD_FEED.address.toLowerCase();
+const USDC_FEED = PRICE_FEED_BY_ADDRESS.get(USDC).address.toLowerCase();
+const LINK_FEED = PRICE_FEED_BY_ADDRESS.get(LINK).address.toLowerCase();
+const DAI_FEED = PRICE_FEED_BY_ADDRESS.get(DAI).address.toLowerCase();
+
+// What each feed answers, by its lowercased address: the price in the feed's
+// own units and the time it was written. A feed that is not here makes the
+// call fail.
+let rounds;
+// The parsed body of every HTTP request the node received.
+let requests;
+let logged;
+
+function round(answer, updatedAt = NOW_SECONDS) {
+    return { answer, updatedAt };
+}
+
+// One JSON-RPC answer, to a latestRoundData() call.
+function reply(req) {
+    const envelope = { jsonrpc: "2.0", id: req.id };
+    const answer = rounds[req.params[0].to.toLowerCase()];
+    if (!answer) {
+        return {
+            ...envelope,
+            error: { code: -32000, message: "fixture: read failed" },
+        };
+    }
+    return {
+        ...envelope,
+        result: AbiCoder.defaultAbiCoder().encode(
+            ["uint80", "int256", "uint256", "uint256", "uint80"],
+            [1, answer.answer, answer.updatedAt, answer.updatedAt, 1],
+        ),
+    };
+}
+
+// The feed addresses one HTTP request read, sorted.
+function feedsRead(body) {
+    return [body]
+        .flat()
+        .map((req) => req.params[0].to.toLowerCase())
+        .sort();
+}
+
+// One address that holds `held`, a list of [contract address, symbol].
+function holdTokens(held) {
+    state.wallets = [
+        {
+            addresses: [
+                {
+                    address: "0x" + "a".repeat(40),
+                    balance: "1.0",
+                    tokenBalances: held.map(([address, symbol]) => ({
+                        address,
+                        symbol,
+                        balance: "10.0",
+                    })),
+                },
+            ],
+        },
+    ];
+}
+
+beforeEach(() => {
+    clearPrices();
+    state.networkId = "mainnet";
+    state.rpcUrl = RPC_URL;
+    state.wallets = [];
+    state.trackedTokens = [];
+    rounds = { [ETH_FEED]: round(2000n * 10n ** 8n) };
+    requests = [];
+    logged = [];
+    jest.spyOn(Date, "now").mockReturnValue(NOW);
+    for (const level of ["error", "warn"]) {
+        jest.spyOn(console, level).mockImplementation((...args) => {
+            logged.push(args.map(String).join(" "));
+        });
+    }
+    FetchRequest.registerGetUrl(async (req) => {
+        const body = JSON.parse(Buffer.from(req.body).toString("utf8"));
+        requests.push(body);
+        const answer = Array.isArray(body) ? body.map(reply) : reply(body);
+        return {
+            statusCode: 200,
+            statusMessage: "OK",
+            headers: { "content-type": "application/json" },
+            body: Buffer.from(JSON.stringify(answer)),
+        };
+    });
+});
+
+afterEach(() => {
+    FetchRequest.registerGetUrl(FetchRequest.createGetUrlFunc());
+    jest.restoreAllMocks();
+    clearPrices();
+});
+
+describe("refreshPrices", () => {
+    test("reads ETH and each held or tracked token that has a feed in one HTTP request", async () => {
+        holdTokens([
+            [USDC, "USDC"],
+            [LINK, "LINK"],
+        ]);
+        state.trackedTokens = [{ address: DAI, symbol: "DAI", decimals: 18 }];
+        rounds[USDC_FEED] = round(10n ** 8n);
+        rounds[LINK_FEED] = round(1150000000n);
+        rounds[DAI_FEED] = round(99990000n);
+
+        await refreshPrices();
+
+        expect(requests).toHaveLength(1);
+        expect(feedsRead(requests[0])).toEqual(
+            [ETH_FEED, USDC_FEED, LINK_FEED, DAI_FEED].sort(),
+        );
+        expect(getPrice("ETH")).toBe(2000);
+        expect(getPrice(USDC)).toBe(1);
+        expect(getPrice(LINK)).toBe(11.5);
+        expect(getPrice(DAI)).toBe(0.9999);
+    });
+
+    test("reads again only once 5 minutes have passed", async () => {
+        await refreshPrices();
+        Date.now.mockReturnValue(NOW + 299999);
+        await refreshPrices();
+        expect(requests).toHaveLength(1);
+
+        Date.now.mockReturnValue(NOW + 300000);
+        rounds[ETH_FEED] = round(2100n * 10n ** 8n, NOW_SECONDS + 300);
+        await refreshPrices();
+        expect(requests).toHaveLength(2);
+        expect(getPrice("ETH")).toBe(2100);
+    });
+
+    test("on Sepolia, reads nothing and keeps no price", async () => {
+        await refreshPrices();
+        expect(getPrice("ETH")).toBe(2000);
+
+        state.networkId = "sepolia";
+        await refreshPrices();
+        expect(requests).toHaveLength(1);
+        expect(Object.keys(prices)).toEqual([]);
+    });
+});
+
+describe("pairing by contract address", () => {
+    test("a token that copies a bundled token's symbol gets no price", async () => {
+        holdTokens([
+            [USDC, "USDC"],
+            [FAKE_USDC, "USDC"],
+        ]);
+        rounds[USDC_FEED] = round(10n ** 8n);
+
+        await refreshPrices();
+
+        expect(feedsRead(requests[0])).toEqual([ETH_FEED, USDC_FEED].sort());
+        expect(getPrice(USDC)).toBe(1);
+        expect(getPrice(FAKE_USDC)).toBeNull();
+        // 1 ETH and 10 real USDC are priced; the 10 look-alikes are not.
+        expect(getAddressValue(state.wallets[0].addresses[0])).toEqual({
+            usd: 2010,
+            partial: true,
+        });
+    });
+});
+
+describe("freshness", () => {
+    test("a reading older than its feed's heartbeat plus 30 minutes is no price", async () => {
+        const heartbeatAgo =
+            NOW_SECONDS - PRICE_FEED_BY_ADDRESS.get(USDC).heartbeat;
+        holdTokens([[USDC, "USDC"]]);
+
+        rounds[USDC_FEED] = round(10n ** 8n, heartbeatAgo - 1800 - 1);
+        await refreshPrices();
+        expect(getPrice(USDC)).toBeNull();
+
+        clearPrices();
+        rounds[USDC_FEED] = round(10n ** 8n, heartbeatAgo - 1800);
+        await refreshPrices();
+        expect(getPrice(USDC)).toBe(1);
+    });
+
+    test.each([0n, -1n])("an answer of %s is no price", async (answer) => {
+        rounds[ETH_FEED] = round(answer);
+        await refreshPrices();
+        expect(getPrice("ETH")).toBeNull();
+    });
+});
+
+describe("a failed read", () => {
+    test("leaves the token with no price and is logged with its error", async () => {
+        holdTokens([[USDC, "USDC"]]);
+        rounds[USDC_FEED] = round(10n ** 8n);
+        await refreshPrices();
+        expect(getPrice(USDC)).toBe(1);
+
+        Date.now.mockReturnValue(NOW + 300000);
+        delete rounds[USDC_FEED];
+        await refreshPrices();
+
+        expect(getPrice(USDC)).toBeNull();
+        expect(getPrice("ETH")).toBe(2000);
+        expect(
+            logged.some(
+                (line) =>
+                    line.includes("price feed read failed") &&
+                    line.includes(USDC),
+            ),
+        ).toBe(true);
+    });
+
+    test("an HTTP error is logged with its status", async () => {
+        FetchRequest.registerGetUrl(async () => ({
+            statusCode: 401,
+            statusMessage: "Unauthorized",
+            headers: { "content-type": "text/plain" },
+            body: Buffer.from("API key required"),
+        }));
+
+        await refreshPrices();
+
+        expect(getPrice("ETH")).toBeNull();
+        expect(logged.some((line) => line.includes("401"))).toBe(true);
+    });
+});
+
+describe("the feed table", () => {
+    test("names each token by its address as the bundled list spells it", () => {
+        const listed = new Set(TOKENS.map((t) => t.address));
+        const unlisted = Object.keys(USD_PRICE_FEEDS).filter(
+            (address) => !listed.has(address),
+        );
+        expect(unlisted).toEqual([]);
+    });
+});

tests/unknownScaleDisplay.test.js

@@ -103,7 +103,7 @@ describe("balanceLine", () => {
     });
 
     test("an unknown quantity produces no fiat figure, a zero one does", () => {
-        prices.NOVEL = 3;
+        prices[NOVEL] = 3;
         const unknown = balanceLine("NOVEL", null, 3, NOVEL);
         const zero = balanceLine("NOVEL", 0, 3, NOVEL);
         // A price times an unknown quantity is not $0.00: that is the same
@@ -162,7 +162,7 @@ describe("getAddressValue", () => {
     // make it incomplete.
     test("an unknown balance makes the total partial, a zero balance does not", () => {
         prices.ETH = 2000;
-        prices.NOVEL = 3;
+        prices[NOVEL] = 3;
         const unknown = getAddressValue(address(null));
         const zero = getAddressValue(address("0.0"));
         expect(unknown).not.toEqual(zero);
@@ -172,7 +172,7 @@ describe("getAddressValue", () => {
 
     test("an unknown balance is not priced as zero of the token", () => {
         prices.ETH = 2000;
-        prices.NOVEL = 3;
+        prices[NOVEL] = 3;
         // The same row with a real quantity of 10 is worth $30. Neither that
         // figure nor a confident $0.00 may be stated for the unknown one.
         expect(getAddressValue(address("10.0"))).toEqual({