[Kayanski]

Which Linear task is linked to this PR?

None yet. Follow-up to JUM-1642 (Relay routes asking users to approve the wrong spender).

Why was it implemented this way?

Some providers, like Relay, only know the ERC-20 spender once /stepTransaction runs. The allowance tasks run before that, so today the backend has to guess the spender, and a wrong guess makes the transaction revert.

Now the backend can leave estimate.approvalAddress empty at routing time and set it in /stepTransaction. A new EthereumCheckAllowanceAfterPrepareTask runs after PrepareTransaction, but only when the spender was empty before prepare and is set after it. It reuses the existing allowance tasks (and adds the approval to the batch in batched mode).

Nothing changes for steps that already have a spender, native permits, Permit2, or steps that skip approval.

Rollout: only send an empty spender to clients on this SDK version. Older versions skip the approval and the transaction reverts.

Visual showcase (Screenshots or Videos)

New approvalAddressAtPrepare.flow.spec.ts covers: approve needed, allowance already enough, batched, spender moved by the re-quote (unchanged), and no spender at all. Without the new task, the first three fail.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the SDK API or adds new features that require documentation, I have updated the documentation in the public-docs repository. (No public API change.)

🤖 Generated with Claude Code

[changeset-bot]

🦋 Changeset detected

Latest commit: 79f4854

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@lifi/sdk-provider-ethereum	Patch
@lifi/sdk-provider-tron	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

📦 Bundle size

✅ No significant changes. Every check is within budget.

@lifi/sdk

	Import	Base	PR	Change	Budget used
⚪	createClient + getQuote	4.31 kB	4.31 kB	—	▰▰▰▰▰▰▰▱▱▱ 72%
⚪	all exports	16.0 kB	16.0 kB	—	▰▰▰▰▰▰▰▰▱▱ 80%
⚪	CJS (no tree-shaking)	19.4 kB	19.4 kB	—	▰▰▰▰▰▰▰▰▱▱ 81%

Providers

	Import	Base	PR	Change	Budget used
⚪	ethereum (+ viem)	96.9 kB	96.8 kB	🔻 −0.07 kB (−0.1%)	▰▰▰▰▰▰▰▰▱▱ 84%
⚪	solana	28.3 kB	28.3 kB	—	▰▰▰▰▰▰▰▰▱▱ 83%
⚪	bitcoin	68.1 kB	68.1 kB	—	▰▰▰▰▰▰▰▰▱▱ 83%
⚪	sui	98.2 kB	98.2 kB	—	▰▰▰▰▰▰▰▰▰▱ 89%
⚪	tron	213.1 kB	213.2 kB	🔺 +0.11 kB (+0.1%)	▰▰▰▰▰▰▰▰▰▱ 92%
⚪	stellar	122.9 kB	122.9 kB	—	▰▰▰▰▰▰▰▰▱▱ 83%
⚪	zcash	6.45 kB	6.45 kB	—	▰▰▰▰▰▰▰▰▱▱ 81%

Full integration

	Import	Base	PR	Change	Budget used
⚪	createClient + all providers	588.2 kB	587.9 kB	🔻 −0.38 kB (−0.1%)	▰▰▰▰▰▰▰▰▰▱ 87%

How to read this

• Sizes are minified + brotli, measured with size-limit the way an app bundles the import: tree-shaken, with all dependencies included except the ones in the check's ignore list (packages the app already has, such as peers).
• Code behind a dynamic import() is counted too, unless the check's name says otherwise.
• 🟠 / 🟢 mark a change of at least 512 B and at least 1% or 5.00 kB. 🔴 means the check is over its budget.
• Budgets live in .size-limit.json. The base commit is measured with the same checks as the PR.

_{79f4854 merged into 6e0e588 · workflow run}

[github-actions]

📦 Preview published under the preview dist-tag.

Install the exact version(s) — @preview moves with the newest preview across PRs:

npm i @lifi/sdk-provider-ethereum@0.0.0-preview-069261a2
npm i @lifi/sdk-provider-tron@0.0.0-preview-069261a2