fix: keep subscription pre-consume refund atomic (#5556)

[cat0825]

⚠️ 提交说明 / PR Notice

Important

• 请提供人工撰写的简洁摘要，避免直接粘贴未经整理的 AI 输出。

📝 变更描述 / Description

将订阅预扣退款改为在同一数据库事务内回退 user_subscriptions.amount_used，并标记 subscription_pre_consume_records 为 refunded。原先在事务中调用 PostConsumeUserSubscriptionDelta 会新开事务，可能出现额度已退回但记录状态未更新，导致重试重复退款。

This PR was AI-assisted and manually reviewed before submission.

🚀 变更类型 / Type of change

• 🐛 Bug 修复 (Bug fix) - 请关联对应 Issue，避免将设计取舍、理解偏差或预期不一致直接归类为 bug
• ✨ 新功能 (New feature) - 重大特性建议先通过 Issue 沟通
• ⚡ 性能优化 / 重构 (Refactor)
• 📝 文档更新 (Documentation)

🔗 关联任务 / Related Issue

• Closes 退款链路，改金额与改状态的数据库事务不一致会导致重复退款问题 #5556

✅ 提交前检查项 / Checklist

• 人工确认: 我已亲自整理并撰写此描述，没有直接粘贴未经处理的 AI 输出。
• 非重复提交: 我已搜索现有的 Issues 与 PRs，确认不是重复提交。
• Bug fix 说明: 若此 PR 标记为 Bug fix，我已提交或关联对应 Issue，且不会将设计取舍、预期不一致或理解偏差直接归类为 bug。
• 变更理解: 我已理解这些更改的工作原理及可能影响。
• 范围聚焦: 本 PR 未包含任何与当前任务无关的代码改动。
• 本地验证: 已在本地运行并通过测试或手动验证，维护者可以据此复核结果。
• 安全合规: 代码中无敏感凭据，且符合项目代码规范。

📸 运行证明 / Proof of Work

docker run --rm -v "$PWD":/work -w /work -e GOMODCACHE=/gomod -e GOCACHE=/gocache golang:1.25.1 go test ./model -run 'TestRefundSubscriptionPreConsume|TestPreConsume|TestCAS|TestUserUpdate'
ok  	github.com/QuantumNous/new-api/model	0.027s

Summary by CodeRabbit

• Bug Fixes

  • Subscription refunds now correctly restore consumed quota within the same transaction.
  • Repeated refunds for the same request remain idempotent and do not apply duplicate adjustments.
  • Consumed amounts are prevented from becoming negative or exceeding the subscription limit.

• Tests

  • Added coverage for subscription pre-consumption refunds and refund record updates.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: bc57f902-d8a8-4de2-8937-dc8649a65e88

📥 Commits

Reviewing files that changed from the base of the PR and between f2c7cd3 and 1a48572.

📒 Files selected for processing (3)

• model/subscription.go
• model/subscription_refund_test.go
• model/task_cas_test.go

---

Walkthrough

Subscription refunds now reverse quota usage through the existing database transaction. The shared delta helper handles locking and validation, while tests verify one-time reversal, record status updates, and test-table cleanup.

Changes

Subscription refund consistency

Layer / File(s)	Summary
Transactional refund delta updates model/subscription.go	Refund processing uses a transaction-scoped quota delta helper that locks the subscription row, clamps usage, enforces the total limit, and saves the updated amount.
Refund idempotency test coverage model/subscription_refund_test.go, model/task_cas_test.go	Tests verify pre-consumption, repeated refunds, refunded record status, table migration, and cleanup of pre-consume records.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Poem

I’m a bunny with a ledger neat,
Refunds now hop on one transaction street.
Quota steps back just once,
Status follows without a chance
For duplicate hops to cheat!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: making subscription pre-consume refunds atomic.
Linked Issues check	✅ Passed	The code updates refund and amount-used changes in one transaction and adds tests for refunded status and idempotent retries.
Out of Scope Changes check	✅ Passed	Changes are limited to the atomic refund fix and supporting test/setup updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

Tools execution failed with the following error:

Failed to run tools: 13 INTERNAL: Received RST_STREAM with code 2 (Internal server error)

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[cat0825]

@Calcium-Ion @t0ng7u 麻烦有空时 review 一下这个 PR。

范围：仅 #5556 — 订阅预扣退款在同一事务内回退 amount_used 并标记 pre-consume 记录，避免重复退款。
本地已补回归测试；CodeRabbit 无 actionable 问题。谢谢。