feat(samples/kotlin): support GRID_API_BASE_URL override

[pengying]

Add an optional GRID_API_BASE_URL environment variable so the Kotlin
sample can target a non-production Grid API base path (e.g. a dev/RC
environment). When unset, the SDK's default base URL is used.

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

[vercel]

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2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
grid-flow-builder	Ignored	Preview	Jun 18, 2026 6:13pm
grid-wallet-demo	Ignored	Preview	Jun 18, 2026 6:13pm

[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
• 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 👈 (View in Graphite)
• main

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[greptile-apps]

Greptile Summary

Adds an optional GRID_API_BASE_URL environment variable to the Kotlin sample so it can target non-production Grid API endpoints; when unset, the SDK's default production URL is used.

• Config.kt gains a private getEnvVarOrNull helper and exposes apiBaseUrl: String?, refactoring the existing getEnvVar to delegate to it.
• GridClientBuilder.kt applies baseUrl(it) on the SDK builder only when apiBaseUrl is non-null, using idiomatic Kotlin apply/let.

Confidence Score: 5/5

Safe to merge — the change is additive and isolated to the Kotlin sample; the SDK default URL is preserved whenever the variable is unset.

The change is a small, self-contained addition to a sample app. The new code path only activates when GRID_API_BASE_URL is explicitly set, and the SDK builder is otherwise untouched. No production code is affected.

No files require special attention.

Important Files Changed

Filename	Overview
samples/kotlin/src/main/kotlin/com/grid/sample/Config.kt	Adds optional GRID_API_BASE_URL env var via a new getEnvVarOrNull helper; refactors getEnvVar to delegate to it. Clean extraction, though blank-string values pass through as non-null (flagged in prior thread).
samples/kotlin/src/main/kotlin/com/grid/sample/GridClientBuilder.kt	Applies apiBaseUrl to the SDK builder only when non-null using idiomatic apply/let; no issues found.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Env as Environment<br/>(sys prop / .env / env var)
    participant Config as Config.kt
    participant Builder as GridClientBuilder.kt
    participant SDK as LightsparkGridOkHttpClient

    Config->>Env: getEnvVar("GRID_CLIENT_ID")
    Env-->>Config: apiTokenId
    Config->>Env: getEnvVar("GRID_CLIENT_SECRET")
    Env-->>Config: apiClientSecret
    Config->>Env: getEnvVarOrNull("GRID_API_BASE_URL")
    Env-->>Config: apiBaseUrl (String? — null if unset)

    Builder->>SDK: builder().username().password()
    alt "apiBaseUrl != null"
        Builder->>SDK: ".apply { baseUrl(apiBaseUrl) }"
    end
    Builder->>SDK: .build()
    SDK-->>Builder: LightsparkGridClient

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sequenceDiagram
    participant Env as Environment<br/>(sys prop / .env / env var)
    participant Config as Config.kt
    participant Builder as GridClientBuilder.kt
    participant SDK as LightsparkGridOkHttpClient

    Config->>Env: getEnvVar("GRID_CLIENT_ID")
    Env-->>Config: apiTokenId
    Config->>Env: getEnvVar("GRID_CLIENT_SECRET")
    Env-->>Config: apiClientSecret
    Config->>Env: getEnvVarOrNull("GRID_API_BASE_URL")
    Env-->>Config: apiBaseUrl (String? — null if unset)

    Builder->>SDK: builder().username().password()
    alt "apiBaseUrl != null"
        Builder->>SDK: ".apply { baseUrl(apiBaseUrl) }"
    end
    Builder->>SDK: .build()
    SDK-->>Builder: LightsparkGridClient

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_{Reviews (2): Last reviewed commit: "feat(samples/kotlin): support GRID_API_B..." | Re-trigger Greptile}

[greptile-apps]

Empty string not treated as "unset"

getEnvVarOrNull returns an empty string if GRID_API_BASE_URL is set to "" (e.g. an accidentally blank .env entry). That empty string is non-null, so apiBaseUrl will be "" and baseUrl("") will be called on the SDK builder — almost certainly producing a malformed URL at runtime instead of silently falling back to the default.

Suggested change

	val apiBaseUrl: String? = getEnvVarOrNull("GRID_API_BASE_URL")
	val apiBaseUrl: String? = getEnvVarOrNull("GRID_API_BASE_URL")?.takeIf { it.isNotBlank() }

Prompt To Fix With AI

This is a comment left during a code review.
Path: samples/kotlin/src/main/kotlin/com/grid/sample/Config.kt
Line: 18

Comment:
**Empty string not treated as "unset"**

`getEnvVarOrNull` returns an empty string if `GRID_API_BASE_URL` is set to `""` (e.g. an accidentally blank `.env` entry). That empty string is non-null, so `apiBaseUrl` will be `""` and `baseUrl("")` will be called on the SDK builder — almost certainly producing a malformed URL at runtime instead of silently falling back to the default.

```suggestion
    val apiBaseUrl: String? = getEnvVarOrNull("GRID_API_BASE_URL")?.takeIf { it.isNotBlank() }
```

How can I resolve this? If you propose a fix, please make it concise.