feat: transaction simulation via viem + Solana simulateTransaction

[premiumjibles]

Summary

• Add client-side transaction simulation before wallet interaction using viem publicClient.call() + estimateGas() for EVM and connection.simulateTransaction() for Solana
• Predicted reverts block the transaction early with a decoded error message — wallet popup is never shown
• RPC/simulation failures degrade gracefully (warn and proceed without simulation)
• Gas estimates with 20% buffer replace hardcoded constants for EVM transactions

Changes

• SimulationError class + isRevertError/extractRevertReason helpers
• simulateEvmTransaction — eth_call revert detection + estimateGas with buffer
• simulateSolanaTransaction — preflight simulation with log extraction
• Integration into sendEvmTransaction and sendSolanaTransaction
• Error display passthrough in getUserFriendlyError

Test Plan

• Unit tests for isRevertError classification (revert vs RPC failure)
• Unit tests for extractRevertReason (shortMessage preference)
• Unit tests for simulateEvmTransaction (revert, non-revert, gas buffer)
• Unit tests for simulateSolanaTransaction (success, error log extraction, fallback)
• Manual: known-good swap — simulation succeeds silently, wallet popup appears
• Manual: known-bad swap (expired quote) — revert detected, error in step UI, no wallet popup
• Manual: RPC failure — console.warn, transaction proceeds normally

🤖 Generated with Claude Code

Closes sg-rzht

Summary by CodeRabbit

• New Features

  • Added pre-transaction simulation to detect potential reverts before submission on EVM and Solana networks.
  • Automatic gas estimation with buffer applied for EVM transactions.

• Bug Fixes

  • Improved error detection and messaging for failed transactions with clearer revert handling.

• Tests

  • Added comprehensive test coverage for transaction simulation and error handling.

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Project	Deployment	Actions	Updated (UTC)
shapeshift-agentic	Ready	Preview, Comment	Mar 12, 2026 1:22am

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 385eb866-a949-45a0-a2e6-70dd45b0d46d

📥 Commits

Reviewing files that changed from the base of the PR and between 2b3965b and 5571ece.

📒 Files selected for processing (9)

• apps/agentic-chat/src/lib/stepUtils.ts
• apps/agentic-chat/src/utils/SimulationError.ts
• apps/agentic-chat/src/utils/__tests__/SimulationError.test.ts
• apps/agentic-chat/src/utils/chains/evm/__tests__/simulation.test.ts
• apps/agentic-chat/src/utils/chains/evm/simulation.ts
• apps/agentic-chat/src/utils/chains/evm/transaction.ts
• apps/agentic-chat/src/utils/chains/solana/__tests__/simulation.test.ts
• apps/agentic-chat/src/utils/chains/solana/simulation.ts
• apps/agentic-chat/src/utils/chains/solana/transaction.ts

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📝 Walkthrough

Walkthrough

The changes implement pre-transaction simulation for EVM and Solana blockchains. A new SimulationError utility class and helper functions detect reverts and extract error reasons. Chain-specific simulators (EVM and Solana) catch failures early with descriptive error handling. The EVM simulator applies a 20% gas buffer. Both chain integrations now invoke simulation before sending transactions. Error mapping utilities are enhanced to handle "transaction will revert" messages directly.

Changes

Cohort / File(s)	Summary
Error Utilities apps/agentic-chat/src/utils/SimulationError.ts, apps/agentic-chat/src/utils/__tests__/SimulationError.test.ts	Introduces SimulationError custom error class, isRevertError() detector, and extractRevertReason() extractor. Tests verify error detection for ContractFunctionRevertedError, CallExecutionError, and revert messages; shortMessage preference; and fallback behavior.
EVM Simulation apps/agentic-chat/src/utils/chains/evm/simulation.ts, apps/agentic-chat/src/utils/chains/evm/__tests__/simulation.test.ts, apps/agentic-chat/src/utils/chains/evm/transaction.ts	Adds simulateEvmTransaction() to detect reverts via publicClient.call(), throw SimulationError with reason, and apply 20% gas buffer to estimateGas(). Tests verify revert handling, reason propagation, and buffer correctness. Integration updates transaction.ts to simulate before execution and handle SimulationError distinctly.
Solana Simulation apps/agentic-chat/src/utils/chains/solana/simulation.ts, apps/agentic-chat/src/utils/chains/solana/__tests__/simulation.test.ts, apps/agentic-chat/src/utils/chains/solana/transaction.ts	Adds simulateSolanaTransaction() to invoke connection.simulateTransaction(), parse logs for error or failed keywords, and throw SimulationError with extracted reason. Tests verify log-based reason extraction and fallback to JSON stringified error. Integration updates transaction.ts to simulate pre-signature with skipPreflight enabled.
Error Mapping apps/agentic-chat/src/lib/stepUtils.ts	Adds detection in getUserFriendlyError(): if raw error contains "transaction will revert", returns the raw error string instead of a mapped message.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 Hops through the chain with care so keen,
Simulating all that might have been,
Reverts detected before they're real,
Gas buffered safe with blockchain zeal,
Both EVM and Solana play,
No nasty surprises come to stay! ✨

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch worktree-sa3-gbzn

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