refactor(tool): extract snapshot export into a shared module

[0xDevNinja]

Summary of changes

The Filecoin.ChainExportDiff RPC method called do_export directly from the archive_cmd CLI subcommand module, coupling the RPC layer to a CLI subcommand (flagged during review of #6074).

Changes introduced in this pull request:

• Moved do_export and its build_output_path helper out of tool::subcommands::archive_cmd into a dedicated crate::tool::export module.
• Both the forest-tool archive/snapshot CLI subcommands and the ChainExportDiff RPC method now import the export logic from that shared module.
• Trimmed the imports that were only used by the moved functions.

This is a pure move with no behaviour change.

Reference issue to close (if applicable)

Closes #6096

Other information and links

Identified during review of #6074 (#6074 (comment)).

I kept the module under crate::tool since the export path still uses CLI-oriented helpers (progress bar, interactive overwrite prompt guarded by force). Happy to move it deeper (e.g. under crate::chain) if you'd prefer to fully separate it from the tooling layer.

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• Bug Fixes

  • Improved differential chain export so the RPC path matches the CLI’s behavior, including finality/depth validation, diff handling, overwrite confirmation, and progress feedback.
  • Export output paths are handled consistently, including when a directory is provided (including CARZST naming).

• Refactor

  • Centralized snapshot/diff export logic into a shared export utility used by both the CLI and RPC flows.

• Tests

  • Updated export tests to use the shared path helper.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 8cf8ab6b-2762-4d5a-bb4d-48d943a09177

📥 Commits

Reviewing files that changed from the base of the PR and between 8e863a5 and 5363567.

📒 Files selected for processing (4)

• src/rpc/methods/chain.rs
• src/tool/export.rs
• src/tool/mod.rs
• src/tool/subcommands/archive_cmd.rs

🔗 Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

• filecoin-project/lotus (manual)

✅ Files skipped from review due to trivial changes (1)

• src/tool/mod.rs

🚧 Files skipped from review as they are similar to previous changes (3)

• src/rpc/methods/chain.rs
• src/tool/subcommands/archive_cmd.rs
• src/tool/export.rs

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Walkthrough

Snapshot export logic is moved into src/tool/export.rs, and both the RPC diff-export path and the CLI archive command now call the shared exporter. The old local implementation in archive_cmd.rs is removed, and the module tree is updated to expose the new code.

Changes

Export logic relocation

Layer / File(s)	Summary
Path building and export validation src/tool/export.rs	Adds build_output_path and the early do_export logic for genesis resolution, network/epoch derivation, and depth/finality validation.
Tipset loading and export execution src/tool/export.rs	Loads the target and diff tipsets, computes the seen set, handles overwrite prompting and file creation, and calls crate::chain::export with the computed state.
Module wiring and caller updates src/tool/mod.rs, src/rpc/methods/chain.rs, src/tool/subcommands/archive_cmd.rs	Registers the new module, retargets the RPC and CLI callers to crate::tool::export::do_export, removes the old local exporter and related imports, and updates the test import.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Sequence Diagram(s)

sequenceDiagram
  participant RPC as ForestChainExportDiff
  participant CLI as archive_cmd
  participant Export as tool::export::do_export
  participant Chain as crate::chain::export

  RPC->>Export: do_export(...)
  CLI->>Export: do_export(...)
  Export->>Export: resolve genesis, validate depth, build seen set
  Export->>Chain: export(writer, seen, options)
  Chain-->>Export: completion
  Export-->>RPC: Ok(())
  Export-->>CLI: Ok(())

Loading

Possibly related PRs

• ChainSafe/forest#6074: Introduces the original ForestChainExportDiff and do_export plumbing that this refactor reuses.
• ChainSafe/forest#7249: Touches the same RPC diff-export handler in src/rpc/methods/chain.rs.
• ChainSafe/forest#7290: Also updates the do_export(...) path used by Filecoin.ChainExportDiff.

Suggested labels: RPC, Snapshot

Suggested reviewers: LesnyRumcajs, akaladarshi

🚥 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 describes the main refactor: extracting snapshot export into a shared module.
Linked Issues check	✅ Passed	The PR extracts export logic into src/tool/export.rs and updates CLI/RPC callers to use it, matching #6096.
Out of Scope Changes check	✅ Passed	The changes stay focused on shared export refactoring and caller updates, with no obvious unrelated additions.
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

✨ Simplify code

• Create PR with simplified code

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

src/tool/export.rs (1)

52-66: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Add a doc comment for the public do_export API.

do_export is now a shared entrypoint with 9 positional parameters (epoch_option, depth, diff, diff_depth, force, …) whose meaning is not obvious from the name alone. A brief /// doc describing the parameters and the diff/full export semantics would help both the CLI and RPC callers. build_output_path is self-explanatory and can keep its existing comment.

As per coding guidelines: "Document public functions and structs with doc comments".

🤖 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 `@src/tool/export.rs` around lines 52 - 66, The public do_export API is missing
a doc comment, making its many positional parameters and full-vs-diff export
behavior hard to understand. Add a brief /// comment above do_export that
explains what the function does, summarizes the roles of the key parameters like
epoch_option, depth, diff, diff_depth, and force, and clarifies the semantics of
full versus diff exports. Leave build_output_path as-is since it already has a
clear comment.

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.

Inline comments:
In `@src/tool/export.rs`:
- Around line 4-5: Update the module doc in export.rs to use the correct RPC
method name: the shared snapshot export logic comment currently references
Filecoin.ChainExportDiff, but it should say Forest.ChainExportDiff. Make this
change in the top-level documentation comment so the symbol description matches
the actual RPC method name used by the export flow.

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Nitpick comments:
In `@src/tool/export.rs`:
- Around line 52-66: The public do_export API is missing a doc comment, making
its many positional parameters and full-vs-diff export behavior hard to
understand. Add a brief /// comment above do_export that explains what the
function does, summarizes the roles of the key parameters like epoch_option,
depth, diff, diff_depth, and force, and clarifies the semantics of full versus
diff exports. Leave build_output_path as-is since it already has a clear
comment.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 50878905-b51d-46b0-980e-4b1562bfaf6c

📥 Commits

Reviewing files that changed from the base of the PR and between 7e7adc2 and 8e863a5.

📒 Files selected for processing (4)

• src/rpc/methods/chain.rs
• src/tool/export.rs
• src/tool/mod.rs
• src/tool/subcommands/archive_cmd.rs

🔗 Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

• filecoin-project/lotus (manual)