fix(samples/kotlin): select crypto network when funding a quote from USDC

[pengying]

A RealtimeFundingQuoteSource with a crypto currency (e.g. USDC) requires a
cryptoNetwork, otherwise the quote fails with INVALID_INPUT ("Crypto network
is required ... for a crypto currency"). Pass cryptoNetwork through the
quotes route and add a Funding Network selector to the quote step, shown
only when the source currency is crypto. Fixes the Payout flow when funding
from USDC.

Co-Authored-By: Claude Opus 4.8 (1M context) noreply@anthropic.com

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2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
grid-flow-builder	Ignored	Preview	Jun 26, 2026 12:23am
grid-wallet-demo	Ignored	Preview	Jun 26, 2026 12:23am

[pengying]

• fix(samples/frontend): floor default quote amount to corridor minimum #605
• fix(samples/frontend): scale default quote amount by source currency decimals #604
• fix(samples/kotlin): select crypto network when funding a quote from USDC #603 👈 (View in Graphite)
• feat(samples/kotlin): add exchange-rates lookup flow #602
• feat(samples/kotlin): add USD → USDC wallet payout flow #593
• fix(samples/kotlin): send customer email for USDB embedded wallets #590
• feat(samples/kotlin): support GRID_API_BASE_URL override #589
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[greptile-apps]

Greptile Summary

This PR fixes the Payout flow when funding from USDC by threading cryptoNetwork through the quote creation path. Without the network field, the API returned INVALID_INPUT: Crypto network is required for crypto funding sources.

• Frontend (CreateQuote.tsx): Adds a CRYPTO_NETWORKS constant (BASE, ETHEREUM, POLYGON, SOLANA), a cryptoNetwork state variable, and a conditional "Funding Network" dropdown that appears only when the selected source currency is in CRYPTO_SOURCE_CURRENCIES. The network is appended to the request body only when isCryptoSource is true.
• Kotlin backend (Quotes.kt): Reads the optional cryptoNetwork field from the incoming JSON and passes it to RealtimeFundingQuoteSource.builder(), matching the existing optional-field pattern used for customerId.

Confidence Score: 5/5

Safe to merge — the change is a minimal, targeted fix that adds an optional field to the crypto funding path without touching any other flows.

Both changes are additive. The frontend conditionally shows the network picker only for crypto sources and conditionally includes the field in the body; non-crypto flows are unchanged. The Kotlin side uses the same optText(...)?let {} pattern already established for customerId, so the field is silently ignored when absent, preserving backward compatibility.

No files require special attention.

Important Files Changed

Filename	Overview
samples/frontend/src/steps/CreateQuote.tsx	Adds conditional cryptoNetwork selector and conditionally includes the field in the request body; deps array correctly updated.
samples/kotlin/src/main/kotlin/com/grid/sample/routes/Quotes.kt	Reads optional cryptoNetwork from the JSON source node and forwards it to the SDK builder; follows the same optional-field pattern used for customerId.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant User
    participant CreateQuote as CreateQuote.tsx
    participant KtorRoute as Quotes.kt (POST /api/quotes)
    participant GridSDK as Grid SDK

    User->>CreateQuote: Select USDC as source currency
    CreateQuote->>CreateQuote: "isCryptoSource = true → show Funding Network dropdown"
    User->>CreateQuote: Select network (e.g. BASE)
    CreateQuote->>CreateQuote: "Build body with source.cryptoNetwork = BASE"
    User->>CreateQuote: Click Create Quote
    CreateQuote->>KtorRoute: "POST /api/quotes {source:{currency:USDC, cryptoNetwork:BASE, ...}}"
    KtorRoute->>KtorRoute: "buildQuoteSource → optText(cryptoNetwork) = BASE"
    KtorRoute->>GridSDK: RealtimeFundingQuoteSource.builder().currency(USDC).cryptoNetwork(BASE).build()
    GridSDK-->>KtorRoute: Quote response
    KtorRoute-->>CreateQuote: 201 JSON
    CreateQuote-->>User: Show response

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant User
    participant CreateQuote as CreateQuote.tsx
    participant KtorRoute as Quotes.kt (POST /api/quotes)
    participant GridSDK as Grid SDK

    User->>CreateQuote: Select USDC as source currency
    CreateQuote->>CreateQuote: "isCryptoSource = true → show Funding Network dropdown"
    User->>CreateQuote: Select network (e.g. BASE)
    CreateQuote->>CreateQuote: "Build body with source.cryptoNetwork = BASE"
    User->>CreateQuote: Click Create Quote
    CreateQuote->>KtorRoute: "POST /api/quotes {source:{currency:USDC, cryptoNetwork:BASE, ...}}"
    KtorRoute->>KtorRoute: "buildQuoteSource → optText(cryptoNetwork) = BASE"
    KtorRoute->>GridSDK: RealtimeFundingQuoteSource.builder().currency(USDC).cryptoNetwork(BASE).build()
    GridSDK-->>KtorRoute: Quote response
    KtorRoute-->>CreateQuote: 201 JSON
    CreateQuote-->>User: Show response

Loading

_{Reviews (2): Last reviewed commit: "fix(samples/kotlin): select crypto netwo..." | Re-trigger Greptile}

[pengying]

Merge activity

• Jun 26, 12:16 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Jun 26, 12:24 AM UTC: Graphite rebased this pull request as part of a merge.
• Jun 26, 12:24 AM UTC: @pengying merged this pull request with Graphite.

The base branch was changed.

[restamp-bot]

a950d97 is a pure rebase onto af8d404. Approving based on @shreyav's previous approval of 51a4aa7.