Validate swap deep links before pre-filling a form

A swap deep link is an external suggestion about a trade. Loading it should populate a reviewable form, not authorize execution or silently replace the user's destination address.

The browser's URL interface provides structured parsing and access to query parameters. Use that parser instead of manually splitting strings, then apply application-specific validation.

Define a small accepted schema

Allow only documented parameters. Validate chain identifiers against supported networks, token addresses against the selected chain and amounts against token precision. Decide how duplicate query keys are handled; rejecting ambiguity is safer than allowing different components to choose different values.

Keep native-asset aliases within your own link schema and translate them through the selected provider adapter. An arbitrary address-like value must not select a spender, router or RPC endpoint.

Give consequential fields visible treatment

If links may specify a recipient, fee setting or slippage value, show those values prominently and apply the product's normal bounds. Never hide them behind a generic “ready to swap” state.

A link should not provide executable calldata that bypasses the normal quote, validation and review flow. If your product supports a separate transaction-import feature, treat it as a distinct capability with its own explicit review.

Keep navigation separate

Validate any return URL against an intentional navigation policy. Do not accept arbitrary script schemes or let an untrusted link become a general redirect mechanism. Tracking parameters should not alter trade construction.

Test encoded delimiters, repeated amount keys, unsupported chains, excessive decimal precision and a recipient that differs from the connected account. The form should either reject the invalid suggestion or make the accepted values clear before a fresh quote is requested.

After parsing, retain the normalized form state rather than repeatedly reading the URL during signing. Otherwise, navigation changes can alter a trade while the wallet prompt is open.