feat(evm/sdk/js): add pyth filler #2832

ali-behjati · 2025-07-04T13:06:59Z

Summary

This change revamps the deprecated EVM SDK to add a utilty for EVM to fill a call with the Pyth data it needs automatically. Under the hood it performs trace calls to detect Pyth contract usage and extracts the IDs from there, then fetches the update data from Hermes and creates a pyth update call.

This change is the alpha version and is subject to change. In the subsequent PRs more improvements will come. Also I'm going to improve the packaging (like dual export, file structure) later.

Please review the change commit-by-commit (the first commit has just removals, and the second one has actual changes).

Rationale

This change makes integrations to Pyth in the pull model easier.

How has this been tested?

Manually tested the code. Tested two different methods in locally forked network (off eth mainnet) and OP Sepolia.

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Copilot

Pull Request Overview

This PR revamps the deprecated EVM SDK to automatically detect and bundle Pyth price update calls into EVM transactions.

Added two tracer utilities (trace-call-many and debug-trace-call) to extract Pyth price feed IDs from RPC traces.
Implemented fillPythUpdate in filler.ts to iteratively trace, fetch data from Hermes, compute fees, and produce bundled calls.
Updated exports (index.ts) and documentation (README.md), removed old examples, and bumped package to 2.0.0-alpha.

Reviewed Changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/tracer/trace-call-many.ts	New batch tracer using `trace_callMany` to pull Pyth feed IDs
src/tracer/debug-trace-call.ts	Recursive tracer using `debug_traceCall` to extract nested feed IDs
src/filler.ts	Core `fillPythUpdate` implementation orchestrating trace + Hermes
src/multicall3-bundler.ts	Bundler combining Pyth update and original call via Multicall3
src/index.ts	Simplified exports exposing only new utilities
README.md	Updated quickstart and examples for `fillPythUpdate` utility

Files not reviewed (1)

pnpm-lock.yaml: Language not supported

Comments suppressed due to low confidence (3)

target_chains/ethereum/sdk/js/README.md:25

Documentation says fillPythUpdate uses trace_callMany by default, but in code defaultConfig.method is set to debug_traceCall. Align the docs with the actual default or update the default behavior in code.

This function uses the `trace_callMany` method by default but can be used with `debug_traceCall` and a bundler as well. See the example below for more information.

target_chains/ethereum/sdk/js/README.md:49

In the example code, a comma is missing after the method: "trace_callMany" property, which makes the snippet invalid JavaScript.

            method: "trace_callMany"

target_chains/ethereum/sdk/js/src/filler.ts:135

[nitpick] Consider adding unit tests for fillPythUpdate (and the tracer helpers) to verify that price feed extraction and iterative update bundling behave correctly under different scenarios.

export async function fillPythUpdate<

Copilot · 2025-07-04T15:24:27Z

target_chains/ethereum/sdk/js/src/tracer/debug-trace-call.ts

+    }
+  }
+  if (trace.calls === undefined) {
+    return new Set();


When trace.calls is undefined, this returns a new empty set and discards any feeds collected in result. It should return the existing result set instead.

Suggested change

return new Set();

return result;

aditya520 · 2025-07-04T16:55:54Z

target_chains/ethereum/sdk/js/src/filler.ts

+  bundler: Bundler;
+  /** Maximum number of iterations to find all required price feeds. Default is 5.
+   * Each iteration traces the current transaction to find new Pyth price feed calls. */
+  maxIter: number;


Why do we need to iterate multiple times to find price feeds?

function increment() public returns (int256) { // Fetch the latest price from Pyth PythStructs.Price memory ethPrice = pyth.getPriceNoOlderThan(0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace, 30); PythStructs.Price memory btcPrice = pyth.getPriceNoOlderThan(0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43, 30); }

Consider a call to the function above is given to the method. The problem is that with the first trace call, the execution reverts at the first price fetch request and we only identify ETH price feed id. We need to iterate again, by bundling the update and call to pass that line to get the BTC price feed id.

cprussin

Looks good, mostly minor nits / suggestions, also the improvements to fillPythUpdate we'd discussed on slack

cprussin · 2025-07-04T16:10:39Z

target_chains/ethereum/sdk/js/README.md

+import { createPublicClient, http } from "viem";
+import { optimismSepolia } from "viem/chains";
+
+async function example() {


Minor thing but since top-level await exists, you don't need the code here to live in a function, and it kind of distracted me a bit when I was reading through the docs here -- when I saw this my immediate thought was "what is the example function returning and where do I use it" -- I'd just put the body at the top level to minimize the distraction.

cprussin · 2025-07-04T17:29:53Z

target_chains/ethereum/sdk/js/README.md

+            data: "0xd09de08a", // Your transaction calldata
+            from: "0x78357316239040e19fC823372cC179ca75e64b81",
+        },
+        "0x0708325268df9f66270f1401206434524814508b", // Pyth contract address


Can we export this as a const? I know that contract manager isn't in a great state but even just manually copying it over seems to be a better experience for now

cprussin · 2025-07-04T17:30:44Z

target_chains/ethereum/sdk/js/README.md

+            from: "0x78357316239040e19fC823372cC179ca75e64b81",
+        },
+        "0x0708325268df9f66270f1401206434524814508b", // Pyth contract address
+        "https://hermes.pyth.network", // Hermes endpoint


Can we make this a const too? Or better yet, can we make this function just automatically derive these two fields from the client, but allow overriding them in the options?

cprussin · 2025-07-04T17:31:45Z

target_chains/ethereum/sdk/js/package.json

-    "typescript": "^4.6.3",
-    "web3": "^1.8.2",
-    "yargs": "^17.4.1"
+    "ts-node": "catalog:",


Is this dependency used anywhere?

cprussin · 2025-07-04T17:36:46Z

target_chains/ethereum/sdk/js/src/filler.ts

+/**
+ * Union type for tracing configuration options
+ */
+export type Config = DebugTraceCallConfig | TraceCallManyConfig;


You can make this type a lot more concise:

export type Config = { maxIter: number } & ( | { method: "trace_callMany" } | { method: "debug_traceCall", bundler: Bundler } );

cprussin · 2025-07-04T17:39:05Z

target_chains/ethereum/sdk/js/src/filler.ts

+  call: CallRequest,
+  pythContractAddress: Address,
+  hermesEndpoint: string,
+  config?: Config,


minor nit but a better way to write the default is:

export async function fillPythUpdate( // ... other args config: Config = { method: "debug_traceCall", bundler: multicall3Bundler, maxIter: 5 } )

cprussin · 2025-07-04T20:38:50Z

target_chains/ethereum/sdk/js/src/index.ts

-};
+export * from "./filler";
+export * from "./multicall3-bundler";
+export * from "./pyth-abi";


As we'd discussed, barrel exports aren't great, I would consider just putting these into the same file -- I know it feels nice to have smaller separated files, but it does add fs read cost at load time for apps that use it. It's not a huge thing, but it adds up across the whole js package ecosystem, so the more packages that stop using barrel exports, the better.

cprussin · 2025-07-04T20:40:06Z

target_chains/ethereum/sdk/js/src/tracer/debug-trace-call.ts

+  pythContractAddress: Address,
+  ignoreParsingErrors = false,
+): Set<`0x${string}`> {
+  const result = new Set<`0x${string}`>();


You can use Address from viem instead of 0x${string}

cprussin · 2025-07-04T20:41:22Z

target_chains/ethereum/sdk/js/src/tracer/debug-trace-call.ts

+    } catch {
+      if (!ignoreParsingErrors) {
+        throw new Error(
+          `Failed to decode calldata: ${trace.input}. Make sure correct Pyth contract address is used.`,
+        );
+      }
+    }


Suggested change

} catch {

if (!ignoreParsingErrors) {

throw new Error(

`Failed to decode calldata: ${trace.input}. Make sure correct Pyth contract address is used.`,

);

}

}

} catch (error: unknown) {

if (!ignoreParsingErrors) {

const thrownError = new Error(

`Failed to decode calldata: ${trace.input}. Make sure correct Pyth contract address is used.`,

);

thrownError.cause = error;

throw thrownError;

}

}

this way you don't lose the context of the underlying error

ali-behjati requested a review from a team as a code owner July 4, 2025 13:07

ali-behjati force-pushed the evm/tx-filler branch 4 times, most recently from da11879 to 5e37390 Compare July 4, 2025 13:22

ali-behjati added 2 commits July 4, 2025 15:24

chore: remove obsolete files

637b6cc

feat(evm/sdk/js): add pyth filler

b443c30

ali-behjati force-pushed the evm/tx-filler branch from 5e37390 to b443c30 Compare July 4, 2025 13:24

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