Add testnet sandbox for BSC Testnet

[Copilot]

No testnet configuration existed, making it impossible to run the auction bots against a test network without manually wiring up all contract addresses and RPC endpoints.

Changes

• .env.testnet.example — new template pre-filled with BSC Testnet RPC/WebSocket endpoints and all Helio Finance testnet contract addresses (VAT, HAY, INTERACTION, DOG, CHAINLINK_AGGREGATOR, SPOT, both token clips/ilks). Only PRIVATE_KEY needs to be supplied.

• package.json — two new scripts using cross-env DOTENV_CONFIG_PATH=.env.testnet to point dotenv at the testnet config:

  yarn startAuctionBot:testnet
  yarn buyFromAuctionBot:testnet
  

  cross-env added as a devDependency for Windows compatibility.

• .gitignore — .env.testnet excluded alongside .env.

• README.md — Testnet Sandbox section added with setup steps.

Original prompt

create testnet sandbox

Created from VS Code.

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Summary by cubic

Adds a BSC Testnet sandbox to run the auction bots with isolated config. Includes .env.testnet.example with Helio testnet addresses, startAuctionBot:testnet and buyFromAuctionBot:testnet scripts using cross-env, README setup steps, and ignores .env.testnet.

^{Written for commit 37c09eb. Summary will update on new commits.}

[cubic-dev-ai]

2 issues found across 5 files

Confidence score: 3/5

• There is a concrete user-facing setup break: .env.testnet.example contains a non-resolvable testnet API URL, so startAuctionBot:testnet will fail out of the box.
• This is why the score is moderate risk rather than high confidence—the top issue is medium severity (6/10) with high confidence, and it impacts first-run behavior directly.
• README.md also has a low-severity documentation mismatch that can prompt users to overwrite a default they expect to work, adding avoidable setup friction.
• Pay close attention to .env.testnet.example, README.md - align the API default and setup instructions so testnet startup works consistently.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="README.md">

<violation number="1" location="README.md:30">
P3: This setup note is misleading: `.env.testnet.example` already points `API` at the testnet service, so telling users they "need to" update it adds an unnecessary step and can cause them to replace a working default.</violation>
</file>

<file name=".env.testnet.example">

<violation number="1" location=".env.testnet.example:14">
P2: The prefilled testnet API URL is not resolvable, so the documented sandbox config breaks `startAuctionBot:testnet` out of the box.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: The prefilled testnet API URL is not resolvable, so the documented sandbox config breaks startAuctionBot:testnet out of the box.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At .env.testnet.example, line 14:

<comment>The prefilled testnet API URL is not resolvable, so the documented sandbox config breaks `startAuctionBot:testnet` out of the box.</comment>

<file context>
@@ -0,0 +1,36 @@
+PRIVATE_KEY="YOUR_PRIVATE_KEY"
+
+# Helio Finance testnet API endpoint (required – provides liquidation candidate data)
+API="https://api-testnet.helio.money"
+
+# Smart contract addresses (BSC Testnet)
</file context>

[cubic-dev-ai]

P3: This setup note is misleading: .env.testnet.example already points API at the testnet service, so telling users they "need to" update it adds an unnecessary step and can cause them to replace a working default.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At README.md, line 30:

<comment>This setup note is misleading: `.env.testnet.example` already points `API` at the testnet service, so telling users they "need to" update it adds an unnecessary step and can cause them to replace a working default.</comment>

<file context>
@@ -6,3 +6,25 @@
+   yarn buyFromAuctionBot:testnet
+   ```
+
+The `.env.testnet.example` file already contains the BSC Testnet contract addresses for the Helio Finance protocol. You only need to provide your own `PRIVATE_KEY` and update the `API` endpoint to point at the testnet liquidation data service.
</file context>

Suggested change

	The `.env.testnet.example` file already contains the BSC Testnet contract addresses for the Helio Finance protocol. You only need to provide your own `PRIVATE_KEY` and update the `API` endpoint to point at the testnet liquidation data service.
	The `.env.testnet.example` file already contains the BSC Testnet contract addresses and testnet `API` endpoint for the Helio Finance protocol. You only need to provide your own `PRIVATE_KEY`.