Add contract storage layout snapshot test to detect breaking migrations

[Kingsman-99]

Overview

Storage key layouts can change silently between contract versions, breaking data migrations. Add a snapshot test that locks the serialized XDR of every storage key so any accidental layout change fails CI.

Acceptance Criteria

• Snapshot test serializes every StorageKey variant to XDR hex and compares against a committed baseline
• Baseline file: tests/snapshots/storage_keys.json — committed to the repo
• Test fails if any key's XDR diverges from the baseline
• Intentional changes: developer updates baseline file explicitly and includes a migration note in the PR
• Test also asserts that no two StorageKey variants produce the same XDR (no collision)
• Snapshot file includes a version comment listing when each key was introduced
• CI step cargo test storage_snapshot runs on every PR
• README section "Storage Key Registry" explains the snapshot policy

[Elsa-tech2026]

@Elsa-tech2026 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Please assign this issue to me

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[Deyanju23]

@Deyanju23 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Can i work on this?

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[legend-esc]

@legend-esc has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Let me work on this issue

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[Israel-light]

@Israel-light has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I’m interested in this issue because it protects contract storage integrity by catching silent layout changes before they reach production. Locking StorageKey XDR representations ensures migrations are intentional and prevents subtle data corruption across contract versions.

I’ve worked with Rust testing and blockchain smart contract code, including writing snapshot-based tests and validating serialization formats. I’m comfortable building deterministic test cases for XDR encoding and enforcing invariants like collision prevention.

I would add a snapshot test that serializes all StorageKey variants into XDR hex and compares them against a committed baseline in tests/snapshots/storage_keys.json, ensuring any divergence fails CI. I would also enforce uniqueness across variants and document the snapshot policy in the README for future migrations.

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[meem08]

@meem08 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi

Please assign me this task. I’ll add a storage layout snapshot test that validates serialized storage keys against a committed baseline, detects collisions, updates CI coverage, and documents the snapshot policy.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @meem08 to this issue.

[drips-wave]

Congratulations, @legend-esc! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @legend-esc: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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