fix(entitlement): invalidate snapshots after reset

[GAlexIHU]

Overview

Backdated entitlement resets can land before an already-persisted balance snapshot. Because that snapshot represents derived state from before the reset, reusing it would skip the reset and return a stale balance.

This change invalidates snapshots after the reset's effective time before saving the replacement reset snapshot. The reset test now verifies that subsequent balance calculations resume from the reset snapshot instead of a stale later one.

Notes for reviewer

• Invalidation runs after the owner lock and in the same transaction as saving the reset snapshot and ending the usage period.
• The existing test already claimed this lifecycle behavior; it now asserts the resulting snapshot selection.

Validation

• nix develop --impure .#ci -c env POSTGRES_HOST=127.0.0.1 go test -tags=dynamic ./openmeter/entitlement/metered -run 'TestResetEntitlementUsage/Should_invalidate_snapshots_after_the_reset_time$' -count=1
• nix develop --impure .#ci -c env POSTGRES_HOST=127.0.0.1 go test -tags=dynamic ./openmeter/entitlement/metered -run '^TestResetEntitlementUsage$' -count=1
• nix develop --impure .#ci -c env POSTGRES_HOST=127.0.0.1 go test -tags=dynamic ./openmeter/entitlement/metered -count=1

Summary by CodeRabbit

• Bug Fixes
  • Fixed usage resets so outdated balance snapshots are invalidated.
  • Ensured recalculated balances correctly reflect backdated resets and subsequent usage.

[coderabbitai]

📝 Walkthrough

Walkthrough

ResetUsageForOwner now invalidates later balance snapshots before saving the reset snapshot. The metered entitlement test documents the backdated reset case and verifies the resulting snapshot state.

Changes

Reset snapshot consistency

Layer / File(s)	Summary
Reset snapshot invalidation and validation openmeter/credit/balance.go, openmeter/entitlement/metered/reset_test.go	ResetUsageForOwner invalidates snapshots after the reset time within the transaction. The test verifies reset success and confirms that the reset-time snapshot is the latest valid snapshot.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• openmeterio/openmeter#4827: Changes balance snapshot invalidation to exclude already-deleted snapshots.

Suggested reviewers: tothandras

🚥 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 and concisely describes the snapshot invalidation fix after entitlement resets.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

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📝 Generate docstrings

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-entitlement-reset-snapshots

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[coderabbitai]

🧹 Nitpick comments (1)

openmeter/credit/balance.go (1)

319-321: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Document the backdated-reset ordering.

Add a short comment before Line 319. This call invalidates later snapshots so the replacement snapshot saved at Line 324 becomes the latest valid state. The ordering and stale-snapshot consequence are not obvious from InvalidateAfter alone.

Suggested comment

+		// Invalidate later snapshots before saving the reset snapshot so a backdated reset
+		// cannot leave stale balance data as the latest valid snapshot.
 		if err := m.BalanceSnapshotService.InvalidateAfter(ctx, ownerID, at); err != nil {

As per coding guidelines, comments should explain non-obvious intent, domain constraints, lifecycle state, and failure consequences.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@openmeter/credit/balance.go` around lines 319 - 321, Add a concise comment
immediately before the BalanceSnapshotService.InvalidateAfter call explaining
that later snapshots are invalidated before saving the replacement snapshot,
ensuring the replacement becomes the latest valid state and preventing stale
backdated snapshots from remaining active.

Source: Coding guidelines

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@openmeter/credit/balance.go`:
- Around line 319-321: Add a concise comment immediately before the
BalanceSnapshotService.InvalidateAfter call explaining that later snapshots are
invalidated before saving the replacement snapshot, ensuring the replacement
becomes the latest valid state and preventing stale backdated snapshots from
remaining active.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 0517c35c-c995-4c7f-ae58-fd471732dcf8

📥 Commits

Reviewing files that changed from the base of the PR and between e395c7d and 0d1eac6.

📒 Files selected for processing (2)

• openmeter/credit/balance.go
• openmeter/entitlement/metered/reset_test.go