Struct FetchPreparation 

#[non_exhaustive]
pub struct FetchPreparation {
    pub dep_sources: DepSources,
    pub in_use: HashMap<PackageName, Vec<ConcreteVersion>>,
    pub selection_context: SelectionContext,
    pub collided_names: HashSet<PackageName>,
}

Inputs fetch_latest_versions_parallel needs, derived from a parsed manifest.

Which sources to fetch (deduped, collision-free — see dedup_dependencies_by_source), each dependency’s currently in-use version(s), and the manifest’s own deps_core::SelectionContext (e.g. Composer’s minimum-stability, #1433).

Built by prepare_fetch, which consolidates three independently hand-rolled copies of this exact dedup -> in-use -> selection-context sequence (deps-lsp’s document/lifecycle.rs and document/fetch.rs, deps-cli’s analyze.rs) so the LSP and CLI fetch-preparation paths can no longer drift apart (#1433).

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

dep_sources: DepSources

Ready to hand to fetch_latest_versions_parallel as-is, or filtered further by a caller that only wants to fetch a subset (e.g. deps-lsp’s fetch_registry_versions_for_change, which fetches only added/version-changed dependencies).

in_use: HashMap<PackageName, Vec<ConcreteVersion>>

dep_name -> [in_use_version, ...], from crate::classify::resolved::collect_in_use_versions.

selection_context: SelectionContext

The manifest’s own deps_core::SelectionContext, from deps_core::ParseResult::selection_context.

collided_names: HashSet<PackageName>

Names dropped by dedup_dependencies_by_source’s collision gate — must be merged into DocumentState::signals.outcomes’ fetch-failure channel by the caller (spec FR-011).