sprawling-storage 0.0.9

The append-only, hash-chained Ledger of a sprawling city, its content store, checkpoints and worktrees.
Documentation 
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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.
// Copyright (c) 2026 2youg1 and the sprawling contributors

//! Which bytes belong to the people who work in the city, and which
//! belong to the city's own bookkeeping.
//!
//! One predicate, because two modules ask the same question for
//! different reasons and an answer that differed between them would be
//! a rule with two homes: the checkpoint stages what a person wrote,
//! and the worktree ceiling weighs what a person wrote. The ledger, the
//! object store, the projections, git's own metadata and the other
//! nodes' trees all live under [`kernel::PROTECTED_METADATA`] and count
//! as neither.
//!
//! Specified by `crates/storage/spec/Worktree.lean` §8-9.

use std::path::Path;

/// True when `relative` names nothing under a protected metadata
/// subtree.
///
/// `relative` is read as a path relative to the city root, and the
/// names of [`kernel::PROTECTED_METADATA`] are looked for in every
/// segment rather than only the first: a building's own rules sit at
/// `<building>/.sprawling/`, and they are the city's bookkeeping
/// wherever they sit. Segment comparison is ASCII-case-insensitive for
/// the reason [`kernel::Address::is_reserved`] gives - Windows resolves
/// `.SPRAWLING` to the same directory.
pub(crate) fn outside_reserved(relative: &Path) -> bool {
    !relative.components().any(|component| {
        component.as_os_str().to_str().is_some_and(|segment| {
            kernel::PROTECTED_METADATA
                .iter()
                .any(|name| segment.eq_ignore_ascii_case(name))
        })
    })
}

#[cfg(test)]
#[allow(
    clippy::unwrap_used,
    clippy::expect_used,
    clippy::panic,
    clippy::indexing_slicing,
    reason = "test code"
)]
mod tests {
    use super::*;

    #[test]
    fn the_city_s_own_bookkeeping_is_never_somebody_s_work() {
        assert!(outside_reserved(Path::new("City.md")));
        assert!(outside_reserved(Path::new("lab/Roadmap.md")));
        assert!(!outside_reserved(Path::new(".sprawling/ledger/a.jsonl")));
        assert!(!outside_reserved(Path::new("lab/.sprawling/CONFIG.toml")));
        // Git's own metadata is nobody's work either: writing it is
        // privilege escalation (`crates/kernel/spec/Address.lean` §8-73).
        assert!(!outside_reserved(Path::new(".git/hooks/pre-run")));
        assert!(!outside_reserved(Path::new("lab/.git/config")));
        // Windows resolves the reserved directory case-insensitively,
        // so this predicate has to as well.
        assert!(!outside_reserved(Path::new(".SPRAWLING/cas")));
    }
}