exchange demo: Sell swap reverts with InsufficientOutput on testnet (slippage too strict) + no visible error in UI

[Alexkoko27]

Describe the bug

While running examples/exchange locally (WSL + Vite), Buy swaps succeed (receipt link appears), but Sell often reverts on tempo testnet with:

• Stablecoin DEX error: InsufficientOutput(InsufficientOutput)

In the default example UI this can look like a no-op (“nothing happens”) because the error isn’t surfaced.

Debugging notes / workaround

1) Surface the error in the UI

Adding basic error handling (e.g. rendering sellSendCalls.error / sellSendCalls.isError, or catching and displaying TransactionExecutionError) makes the revert reason visible instead of looking like nothing happened.

2) Adjust slippage tolerance on testnet

The default slippage tolerance is 0.5% (0.005). On current testnet liquidity this was too strict and caused InsufficientOutput. Increasing it to ~50% made Sell succeed reliably:

// default
const slippageTolerance = 0.005

// workaround (testnet)
const slippageTolerance = 0.5

Suggestion: expose slippage as a UI input (or use a higher default on testnet) and surface errors by default.

Example successful sell tx (after workaround): https://explore.tempo.xyz/tx/0x3e35dfaa6110be7269425e1556706bb8a59dac94e8b5d6f509ee671287b4552b

Steps to reproduce

1. Clone the example:

   pnpx gitpick tempoxyz/examples/tree/main/examples/exchange exchange
   cd exchange
   pnpm install
   pnpm dev --host 0.0.0.0 --port 5173

2. Open http://localhost:5173
3. Sign up / Sign in
4. Click Fund Account
5. (Optional) Click Place Order
6. Click Sell 10 AlphaUSD for BetaUSD
7. Observe revert: \InsufficientOutput

Logs

TransactionExecutionError: Execution reverted with reason:
Stablecoin DEX error: InsufficientOutput(InsufficientOutput)
viem@2.46.2

Platform(s)

Windows (x86)

Container Type

Other, Not running in a container

What version/commit are you on?

Main branch (pulled from tempoxyz/examples via gitpick from examples/exchange).
No container (running locally on Windows 11 + WSL (Ubuntu)).

If you've built from source, provide the full command you used

pnpx gitpick tempoxyz/examples/tree/main/examples/exchange exchange && cd exchange && pnpm install && pnpm dev --host 0.0.0.0 --port 5173

Code of Conduct

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