[TIME-TRAVEL] [FEAT] Support capturing 'Env' host variables in snapshots

[dotandev]

Description

Ledger state is not just contract storage. It also includes protocol version, sequence numbers, and timestamps.

Requirements

• Extract the current LedgerInfo and Env configuration from the host in simulator/src/state.rs.
• Store these as a sub-struct HostEnv in the snapshot.
• Allow detection of changes to these variables (e.g., protocol upgrades during block boundaries).

Acceptance Criteria

• Env variables are captured alongside storage entries.
• Snapshot diff can identify changes to ledger parameters.

Estimated File Changes: 2 (simulator/src/types.rs, simulator/src/state.rs)

[Zhaenyra]

@Zhaenyra has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I understand the need to capture host-level Env variables as part of time-travel snapshots to reflect full ledger state context. The objective is to extract LedgerInfo and Env configuration, store them in a HostEnv sub-struct, and enable snapshot diffs to detect protocol-level changes.

Implementation plan:

• Extend snapshot data model in simulator/src/types.rs with a HostEnv struct containing protocol version, sequence number, timestamp, and relevant Env configuration fields
• Update snapshot construction in simulator/src/state.rs to extract current LedgerInfo and Env values from the host runtime
• Serialize and persist HostEnv alongside storage entries within snapshot structure
• Integrate HostEnv comparison logic into existing snapshot diff mechanism to highlight changes in ledger parameters
• Ensure backward compatibility by defaulting HostEnv fields when older snapshots lack these attributes

Testing approach and scope boundaries: unit test extraction of LedgerInfo and Env fields, validate snapshot serialization/deserialization, confirm diff correctly flags protocol parameter changes; exclude broader host execution refactors.

Commit message: Capture HostEnv ledger variables in snapshots and include in diff detection

Please assign this issue to me.

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

[drips-wave]

Congratulations, @Zhaenyra! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @Zhaenyra: 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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