OXYGENHUB
# b4fa2bc1ca6a oxygen / crates / oxy-core / src / repo / sync.rs
44.5 KiB · Rust · last changed Lazy blobs: clone --max-blob / filter.max-blob, absent-blob registry fetched on first read, objects endpoint (spec 0.6e) 1 month ago source blame history raw
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//! Serving and talking to remotes (spec §10.2, §16).
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use super::*;
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/// What a fetch brought in.
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#[derive(Debug, Clone, PartialEq, Eq, Default)]
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pub struct FetchReport {
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    /// Bookmark name, its heads, and how many changes were new.
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    pub refs: Vec<(String, Vec<ChangeHash>, usize)>,
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    /// Tags adopted from the remote.
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    pub new_tags: usize,
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    /// The remote has never presented a policy, so nothing was verified
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    /// against one (spec §14.5: warn loudly).
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    pub unverified: bool,
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}
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct PullReport {
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    pub heads: Vec<ChangeHash>,
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    pub changed: bool,
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    pub checked_out: bool,
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}
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impl Repo {
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    // ------------------------------------------------------------ serving (spec §16)
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    fn ref_attest_path(&self, bookmark: &str) -> PathBuf {
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        self.oxy.join("attest").join(bookmark)
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    }
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    /// The latest reference attestation stored for a bookmark.
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    pub fn latest_ref_attest(&self, bookmark: &str) -> Result<Option<(ObjectRef, SignedAttest)>> {
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        match fs::read_to_string(self.ref_attest_path(bookmark)) {
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            Ok(h) => {
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                let r = ObjectRef::from_hex(h.trim()).ok_or_else(|| RepoError::Msg("corrupt attestation pointer".into()))?;
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                Ok(Some((r, SignedAttest { attest: self.store.get_attest(&r)?, sigs: self.store.signatures(&r)? })))
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            }
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            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(None),
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            Err(e) => Err(e.into()),
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        }
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    }
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    fn set_ref_attest(&self, bookmark: &str, r: &ObjectRef) -> Result<()> {
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        fs::create_dir_all(self.oxy.join("attest"))?;
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        write_atomic(&self.ref_attest_path(bookmark), r.to_hex().as_bytes())
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    }
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    pub fn remote_refs(&self) -> Result<RefsResponse> {
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        let view = self.view()?;
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        let mut out = Vec::new();
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        for (name, state) in &view.bookmarks {
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            let latest = self.latest_ref_attest(name)?.map(|(_, a)| a);
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            let last_serial = latest.as_ref().and_then(|a| match a.attest.body {
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                AttestBody::Ref { serial, .. } => Some(serial),
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                _ => None,
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            });
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            let attestation = latest.filter(|a| matches!(&a.attest.body, AttestBody::Ref { new_state, .. } if new_state == state));
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            out.push(RemoteRef { name: name.clone(), state: *state, heads: self.store.get_state(state)?.heads, attestation, last_serial });
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        }
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        let policy = self.current_policy()?.map(|(_, sp)| sp);
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        let history = self.policy_history()?.into_iter().filter(|sp| policy.as_ref().is_some_and(|p| sp.policy.serial < p.policy.serial)).collect();
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        Ok(RefsResponse { refs: out, policy, tags: self.tag_refs()?, history })
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    }
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    /// Every change reachable from `heads` that is in the store.
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    fn closure_in_store(&self, heads: &[ChangeHash]) -> Result<BTreeSet<ChangeHash>> {
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        let mut seen = BTreeSet::new();
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        let mut stack: Vec<ChangeHash> = heads.to_vec();
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        while let Some(h) = stack.pop() {
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            if seen.contains(&h) || !self.store.has(&h) {
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                continue;
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            }
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            seen.insert(h);
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            stack.extend(self.store.get_change(&h)?.deps);
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        }
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        Ok(seen)
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    }
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    /// The changes within `depth` dependency steps of `heads` (spec §17),
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    /// nearest first; depth 1 is the heads themselves.
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    pub fn shallow_changes(&self, heads: &[ChangeHash], depth: u32) -> Result<Vec<ChangeHash>> {
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        let mut out = Vec::new();
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        let mut seen: BTreeSet<ChangeHash> = BTreeSet::new();
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        let mut layer: Vec<ChangeHash> = heads.to_vec();
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        for _ in 0..depth.max(1) {
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            let mut next = Vec::new();
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            for h in layer {
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                if !seen.insert(h) || !self.store.has(&h) {
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                    continue;
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                }
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                let c = self.store.get_change(&h)?;
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                next.extend(c.deps.iter().copied());
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                out.push(h);
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            }
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            if next.is_empty() {
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                break;
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            }
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            layer = next;
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        }
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        out.reverse();
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        Ok(out)
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    }
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    fn shallow_path(&self) -> PathBuf {
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        self.oxy.join("shallow")
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    }
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    /// The shallow boundary: dependencies this repository does not hold (spec §17).
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    pub fn boundary(&self) -> BTreeSet<ChangeHash> {
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        fs::read_to_string(self.shallow_path()).map(|t| t.lines().filter_map(ObjectRef::from_hex).collect()).unwrap_or_default()
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    }
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    pub fn is_shallow(&self) -> bool {
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        !self.boundary().is_empty()
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    }
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    fn write_boundary(&self, boundary: &BTreeSet<ChangeHash>) -> Result<()> {
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        if boundary.is_empty() {
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            let _ = fs::remove_file(self.shallow_path());
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            return Ok(());
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        }
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        let text: String = boundary.iter().map(|h| format!("{}\n", h.to_hex())).collect();
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        write_atomic(&self.shallow_path(), text.as_bytes())
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    }
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    /// Recompute the boundary from what is stored: every dependency of a
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    /// stored change that is not itself stored.
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    fn refresh_boundary(&self, imported: &[ChangeHash]) -> Result<()> {
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        let mut boundary = self.boundary();
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        boundary.retain(|h| !self.store.has(h));
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        for h in imported {
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            for d in self.store.get_change(h)?.deps {
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                if !self.store.has(&d) {
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                    boundary.insert(d);
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                }
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            }
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        }
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        self.write_boundary(&boundary)
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    }
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    /// Fetch `depth` more levels of history below the shallow boundary.
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    pub fn deepen(&self, remote_name: &str, depth: u32) -> Result<usize> {
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        let boundary = self.boundary();
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        if boundary.is_empty() {
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            return Ok(0);
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        }
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        let remote = self.open_named_remote(remote_name)?;
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        let wanted = remote.shallow(&boundary.iter().copied().collect::<Vec<_>>(), depth)?;
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        let bundle = remote.fetch(&wanted, self.config.max_blob)?;
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        let imported = self.import_bundle_shallow(&bundle, false)?;
151 
        if self.config.max_blob.is_some() {
152 
            self.register_missing_blobs(&imported, remote_name)?;
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        }
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        self.refresh_boundary(&imported)?;
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        Ok(imported.len())
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    }
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    /// `closure(want) \ closure(have)`, dependencies first (spec §16.2).
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    pub fn negotiate(&self, have: &[ChangeHash], want: &[ChangeHash]) -> Result<Vec<ChangeHash>> {
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        let have = self.closure_in_store(have)?;
161 
        // In a shallow repository the walk stops at the boundary, whose
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        // changes the remote is assumed to hold.
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        let boundary = self.boundary();
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        let mut out = Vec::new();
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        let mut done: BTreeSet<ChangeHash> = have.clone();
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        done.extend(boundary.iter().copied());
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        // Iterative post-order DFS.
168 
        let mut stack: Vec<(ChangeHash, bool)> = want.iter().rev().map(|h| (*h, false)).collect();
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        while let Some((h, expanded)) = stack.pop() {
170 
            if done.contains(&h) {
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                continue;
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            }
173 
            if !self.store.has(&h) {
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                return fail(format!("change {} is not in this repository", h.short(12)));
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            }
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            if expanded {
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                done.insert(h);
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                out.push(h);
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                continue;
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            }
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            stack.push((h, true));
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            for d in self.store.get_change(&h)?.deps {
183 
                if !done.contains(&d) {
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                    stack.push((d, false));
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                }
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            }
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        }
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        Ok(out)
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    }
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    /// Bundle changes (in the given dependency order) with their signatures,
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    /// seals, identities, blobs, chunks.
193 
    pub fn bundle_for(&self, changes: &[ChangeHash]) -> Result<Bundle> {
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        self.bundle_for_filtered(changes, None)
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    }
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    /// Objects by reference for the `objects` endpoint; a blob brings its chunks.
198 
    pub fn objects_for(&self, refs: &[ObjectRef]) -> Result<Vec<(ObjectType, Vec<u8>)>> {
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        let mut out = Vec::new();
200 
        for r in refs {
201 
            let (ty, body) = match self.store.get(r) {
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                Ok(x) => x,
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                Err(StoreError::NotFound(_)) => continue,
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                Err(e) => return Err(e.into()),
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            };
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            if ty == ObjectType::Blob {
207 
                for c in Blob::decode(&body)?.chunks {
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                    if let Ok((cty, cb)) = self.store.get(&c) {
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                        out.push((cty, cb));
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                    }
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                }
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            }
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            out.push((ty, body));
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        }
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        Ok(out)
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    }
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    /// Like `bundle_for`, leaving out blobs larger than `max_blob` bytes
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    /// (and their chunks) so the receiver fetches them lazily (spec §13.5).
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    pub fn bundle_for_filtered(&self, changes: &[ChangeHash], max_blob: Option<u64>) -> Result<Bundle> {
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        let mut bundle = Bundle::default();
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        let mut objects: BTreeSet<ObjectRef> = BTreeSet::new();
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        let mut seals: BTreeSet<ObjectRef> = BTreeSet::new();
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        let add_object = |r: &ObjectRef, objects: &mut BTreeSet<ObjectRef>| {
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            if !r.is_zero() && self.store.has(r) {
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                objects.insert(*r);
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            }
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        };
229 
        for h in changes {
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            let c = self.store.get_change(h)?;
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            let sigs = self.store.signatures(h)?;
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            add_object(&c.author, &mut objects);
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            for s in &sigs {
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                add_object(&s.key, &mut objects);
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            }
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            for e in &c.edits {
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                if let Edit::Replace { old, new, .. } = e {
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                    for b in [old, new].into_iter().flatten() {
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                        if self.store.has(b) {
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                            if let Ok(blob) = Blob::decode(&self.store.get_typed(b, ObjectType::Blob)?) {
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                                if max_blob.is_some_and(|m| blob.length > m) {
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                                    continue;
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                                }
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                                objects.insert(*b);
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                                objects.extend(blob.chunks.iter().copied());
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                            }
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                        }
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                    }
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                }
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            }
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            for s in self.store.seals_for(h)? {
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                seals.insert(s);
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            }
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            bundle.changes.push((c, sigs));
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        }
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        for r in seals {
257 
            let attest = self.store.get_attest(&r)?;
258 
            let sigs = self.store.signatures(&r)?;
259 
            for s in &sigs {
260 
                add_object(&s.key, &mut objects);
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            }
262 
            bundle.attests.push(SignedAttest { attest, sigs });
263 
        }
264 
        for r in objects {
265 
            let (ty, body) = self.store.get(&r)?;
266 
            bundle.objects.push((ty, body));
267 
        }
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        Ok(bundle)
269 
    }
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    /// Store a bundle's contents. With `strict`, every change must
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    /// authenticate (signature or seal by its author or a delegate).
273 
    pub fn import_bundle(&self, bundle: &Bundle, strict: bool) -> Result<Vec<ChangeHash>> {
274 
        self.import_bundle_inner(bundle, strict, false)
275 
    }
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    /// Like `import_bundle`, accepting changes whose dependencies are absent
278 
    /// (they join the shallow boundary).
279 
    pub fn import_bundle_shallow(&self, bundle: &Bundle, strict: bool) -> Result<Vec<ChangeHash>> {
280 
        self.import_bundle_inner(bundle, strict, true)
281 
    }
282
283 
    fn import_bundle_inner(&self, bundle: &Bundle, strict: bool, shallow: bool) -> Result<Vec<ChangeHash>> {
284 
        for (ty, body) in &bundle.objects {
285 
            match ty {
286 
                ObjectType::Chunk | ObjectType::Blob | ObjectType::Identity | ObjectType::State | ObjectType::Checkpoint => {
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                    self.store.put(*ty, body)?;
288 
                }
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                other => return fail(format!("bundle may not carry {} objects", other.name())),
290 
            }
291 
        }
292 
        for sa in &bundle.attests {
293 
            let r = self.store.put_attest(&sa.attest)?;
294 
            for sig in &sa.sigs {
295 
                self.store.put_signature(&r, sig)?;
296 
            }
297 
            if let AttestBody::Seal { hashes } = &sa.attest.body {
298 
                for h in hashes {
299 
                    self.store.index_seal(h, &r)?;
300 
                }
301 
            }
302 
        }
303 
        let incoming: BTreeSet<ChangeHash> = bundle.changes.iter().map(|(c, _)| c.hash()).collect();
304 
        let boundary = self.boundary();
305 
        let mut imported = Vec::new();
306 
        for (c, sigs) in &bundle.changes {
307 
            let h = c.hash();
308 
            for d in &c.deps {
309 
                if !self.store.has(d) && !incoming.contains(d) && !shallow && !boundary.contains(d) {
310 
                    return fail(format!("change {} depends on {}, which is neither stored nor in the bundle", h.short(12), d.short(12)));
311 
                }
312 
            }
313 
            self.store.put_change(c)?;
314 
            for sig in sigs {
315 
                self.store.put_signature(&h, sig)?;
316 
            }
317 
            imported.push(h);
318 
        }
319 
        if strict {
320 
            for h in &imported {
321 
                if !matches!(self.authenticate_change(h)?, SignatureStatus::Valid { .. }) {
322 
                    return fail(format!("change {} is not authenticated by its author", h.short(12)));
323 
                }
324 
            }
325 
        }
326 
        Ok(imported)
327 
    }
328
329 
    /// Verify a reference attestation against an update it claims to describe.
330 
    /// `allow_equal` lets a client re-read the attestation it already has; a
331 
    /// server receiving a push requires a strictly greater serial.
332 
    fn check_ref_attest(&self, sa: &SignedAttest, name: &str, old_state: &ObjectRef, new_state: &ObjectRef, last_serial: Option<u64>, allow_equal: bool) -> std::result::Result<u64, String> {
333 
        let AttestBody::Ref { name: n, old_state: o, new_state: nw, serial } = &sa.attest.body else {
334 
            return Err("attestation is not a ref attestation".into());
335 
        };
336 
        if n != name || o != old_state || nw != new_state {
337 
            return Err("attestation does not describe this update".into());
338 
        }
339 
        if sa.attest.repo != self.id().map_err(|e| e.to_string())? {
340 
            return Err("attestation is for a different repository".into());
341 
        }
342 
        if let Some(last) = last_serial {
343 
            if *serial < last || (*serial == last && !allow_equal) {
344 
                return Err(format!("attestation serial {serial} is not greater than the last seen {last}"));
345 
            }
346 
        }
347 
        let r = sa.attest.hash();
348 
        let sig = sa.sigs.first().ok_or("attestation carries no signature")?;
349 
        let id = self.store.get_identity(&sig.key).map_err(|_| format!("unknown key {}", sig.key.short(12)))?;
350 
        verify_signature(&id, sig, Domain::Attest, &r).map_err(|e| e.to_string())?;
351 
        Ok(*serial)
352 
    }
353
354 
    /// Accept a push (spec §16.4). Without a trust policy every repository
355 
    /// is unverified, so unsigned changes and unattested updates are accepted;
356 
    /// attestations that are present must still be valid. With a policy,
357 
    /// every change and update is checked against it. A newer policy in the
358 
    /// push is applied first when it is signed by the current roots.
359 
    pub fn receive_push(&self, bundle: Bundle, updates: Vec<RefUpdate>, policy: Option<SignedPolicy>, tags: Vec<crate::protocol::TagRef>) -> Result<Vec<RefResult>> {
360 
        let mut results = Vec::new();
361 
        if let Some(sp) = policy {
362 
            match self.adopt_policy_chain(&bundle.policies, &sp, "push received") {
363 
                Ok(()) => {
364 
                    results.push(RefResult { name: "policy".into(), ok: true, reason: format!("serial {}", sp.policy.serial) });
365 
                }
366 
                Err(e) => {
367 
                    results.push(RefResult { name: "policy".into(), ok: false, reason: e });
368 
                    for u in updates {
369 
                        results.push(RefResult { name: u.name, ok: false, reason: "policy update was rejected".into() });
370 
                    }
371 
                    return Ok(results);
372 
                }
373 
            }
374 
        }
375 
        let policy = self.current_policy()?.map(|(_, sp)| sp.policy);
376 
        if let Err(e) = self.import_bundle(&bundle, policy.is_some()) {
377 
            for u in updates {
378 
                results.push(RefResult { name: u.name, ok: false, reason: e.to_string() });
379 
            }
380 
            return Ok(results);
381 
        }
382 
        let (op_ref, op) = self.head_op()?;
383 
        let mut view = op.view.clone();
384 
        let mut names = Vec::new();
385 
        for u in updates {
386 
            let outcome = self.apply_update(&mut view, &u, policy.as_ref());
387 
            let (ok, reason) = match outcome {
388 
                Ok(()) => (true, String::new()),
389 
                Err(e) => (false, e),
390 
            };
391 
            if ok {
392 
                names.push(u.name.clone());
393 
            }
394 
            results.push(RefResult { name: u.name, ok, reason });
395 
        }
396 
        for t in &tags {
397 
            let name = format!("tags/{}", t.name);
398 
            match self.adopt_tag(&mut view, t, policy.as_ref()) {
399 
                Ok(()) => {
400 
                    names.push(name.clone());
401 
                    results.push(RefResult { name, ok: true, reason: String::new() });
402 
                }
403 
                Err(e) => results.push(RefResult { name, ok: false, reason: e }),
404 
            }
405 
        }
406 
        if !names.is_empty() {
407 
            self.record_op(&[op_ref], &format!("push received: {}", names.join(" ")), view)?;
408 
        }
409 
        Ok(results)
410 
    }
411
412 
    fn apply_update(&self, view: &mut View, u: &RefUpdate, policy: Option<&crate::policy::Policy>) -> std::result::Result<(), String> {
413 
        if u.name == "policy" {
414 
            return Err("the policy reference is updated by sending a policy, not a bookmark update".into());
415 
        }
416 
        let empty = self.store.put_state(&StateObject::new(vec![])).map_err(|e| e.to_string())?;
417 
        let current = view.bookmarks.get(&u.name).copied().unwrap_or(empty);
418 
        if current != u.old_state {
419 
            return Err("stale: the remote bookmark has moved; pull first".into());
420 
        }
421 
        let new_state = self.store.get_state(&u.new_state).map_err(|_| "new state object is missing".to_string())?;
422 
        for h in &new_state.heads {
423 
            if !self.store.has(h) {
424 
                return Err(format!("head {} is missing", h.short(12)));
425 
            }
426 
        }
427 
        if !u.force {
428 
            let old_heads = self.store.get_state(&current).map_err(|e| e.to_string())?.heads;
429 
            let closure = self.closure_in_store(&new_state.heads).map_err(|e| e.to_string())?;
430 
            if let Some(h) = old_heads.iter().find(|h| !closure.contains(h)) {
431 
                return Err(format!("not a fast-forward: current head {} would be dropped (use --force)", h.short(12)));
432 
            }
433 
        }
434 
        if let Some(p) = policy {
435 
            let Some(sa) = &u.attestation else {
436 
                return Err(format!("{:?} requires a signed reference attestation under this repository's policy", u.name));
437 
            };
438 
            let signer = sa.sigs.first().map(|s| s.key).ok_or("attestation carries no signature")?;
439 
            if !p.authorizes(&signer, &u.name) {
440 
                return Err(format!("key {} may not update {:?} under this repository's policy", signer.short(12), u.name));
441 
            }
442 
            let old_heads = self.store.get_state(&current).map_err(|e| e.to_string())?.heads;
443 
            self.state_allowed(&old_heads, &new_state.heads, p, &u.name)?;
444 
        }
445 
        if let Some(sa) = &u.attestation {
446 
            let last = self.latest_ref_attest(&u.name).map_err(|e| e.to_string())?.and_then(|(_, a)| match a.attest.body {
447 
                AttestBody::Ref { serial, .. } => Some(serial),
448 
                _ => None,
449 
            });
450 
            self.check_ref_attest(sa, &u.name, &u.old_state, &u.new_state, last, false)?;
451 
            let r = self.store.put_attest(&sa.attest).map_err(|e| e.to_string())?;
452 
            for sig in &sa.sigs {
453 
                self.store.put_signature(&r, sig).map_err(|e| e.to_string())?;
454 
            }
455 
            self.set_ref_attest(&u.name, &r).map_err(|e| e.to_string())?;
456 
        }
457 
        view.bookmarks.insert(u.name.clone(), u.new_state);
458 
        Ok(())
459 
    }
460
461 
    // ------------------------------------------------------------ client side
462
463 
    fn remote_url(&self, name: &str) -> Result<String> {
464 
        self.config.remotes.get(name).cloned().ok_or_else(|| RepoError::Msg(format!("no remote named {name:?}; add one with `oxy remote add`")))
465 
    }
466
467 
    /// Credentials and trust for a remote: `remote.<name>.token` (else
468 
    /// `$OXY_TOKEN`) and `remote.<name>.ca` (else `$OXY_CA`).
469 
    fn remote_options(&self, name: &str) -> RemoteOptions {
470 
        RemoteOptions {
471 
            token: self.config.remote_tokens.get(name).cloned().or_else(|| std::env::var("OXY_TOKEN").ok()),
472 
            ca: self.config.remote_cas.get(name).map(PathBuf::from).or_else(|| std::env::var("OXY_CA").ok().map(PathBuf::from)),
473 
        }
474 
    }
475
476 
    fn open_named_remote(&self, name: &str) -> Result<Box<dyn crate::protocol::Remote>> {
477 
        open_remote(&self.remote_url(name)?, &self.remote_options(name))
478 
    }
479
480 
    fn serial_path(&self, remote: &str, bookmark: &str) -> PathBuf {
481 
        self.oxy.join("remotes").join(remote).join(format!("{bookmark}.serial"))
482 
    }
483
484 
    fn last_seen_serial(&self, remote: &str, bookmark: &str) -> Option<u64> {
485 
        fs::read_to_string(self.serial_path(remote, bookmark)).ok().and_then(|s| s.trim().parse().ok())
486 
    }
487
488 
    fn record_serial(&self, remote: &str, bookmark: &str, serial: u64) -> Result<()> {
489 
        let p = self.serial_path(remote, bookmark);
490 
        fs::create_dir_all(p.parent().unwrap())?;
491 
        write_atomic(&p, serial.to_string().as_bytes())
492 
    }
493
494 
    fn policy_serial_path(&self, remote: &str) -> PathBuf {
495 
        self.oxy.join("remotes").join(remote).join("policy.serial")
496 
    }
497
498 
    /// The highest policy serial `remote` has ever presented.
499 
    fn remote_policy_serial(&self, remote: &str) -> Option<u64> {
500 
        fs::read_to_string(self.policy_serial_path(remote)).ok().and_then(|s| s.trim().parse().ok())
501 
    }
502
503 
    fn record_policy_serial(&self, remote: &str, serial: u64) -> Result<()> {
504 
        let p = self.policy_serial_path(remote);
505 
        fs::create_dir_all(p.parent().unwrap())?;
506 
        write_atomic(&p, serial.to_string().as_bytes())
507 
    }
508
509 
    fn lazy_dir(&self) -> PathBuf {
510 
        self.oxy.join("lazy")
511 
    }
512
513 
    /// Remember that `blob` was withheld by `remote` (spec §13.5).
514 
    fn register_lazy(&self, blob: &ObjectRef, remote: &str) -> Result<()> {
515 
        fs::create_dir_all(self.lazy_dir())?;
516 
        write_atomic(&self.lazy_dir().join(blob.to_hex()), remote.as_bytes())
517 
    }
518
519 
    /// Which remote promised an absent blob, if any.
520 
    pub fn lazy_remote(&self, blob: &ObjectRef) -> Option<String> {
521 
        fs::read_to_string(self.lazy_dir().join(blob.to_hex())).ok().map(|s| s.trim().to_string())
522 
    }
523
524 
    /// Fetch an absent blob (and its chunks) from the remote that promised it.
525 
    pub(crate) fn fetch_lazy_blob(&self, blob: &ObjectRef) -> Result<()> {
526 
        let Some(remote_name) = self.lazy_remote(blob) else {
527 
            return Err(RepoError::Store(StoreError::NotFound(*blob)));
528 
        };
529 
        let remote = self.open_named_remote(&remote_name)?;
530 
        let objects = remote.objects(&[*blob])?;
531 
        for (ty, body) in objects {
532 
            if matches!(ty, ObjectType::Blob | ObjectType::Chunk) {
533 
                self.store.put(ty, &body)?;
534 
            }
535 
        }
536 
        if !self.store.has(blob) {
537 
            return fail(format!("{remote_name} did not send blob {}", blob.short(12)));
538 
        }
539 
        let _ = fs::remove_file(self.lazy_dir().join(blob.to_hex()));
540 
        Ok(())
541 
    }
542
543 
    /// After importing from `remote`, record every blob the changes reference
544 
    /// that the store lacks as lazily available from that remote.
545 
    fn register_missing_blobs(&self, changes: &[ChangeHash], remote: &str) -> Result<usize> {
546 
        let mut n = 0;
547 
        for h in changes {
548 
            let c = self.store.get_change(h)?;
549 
            for e in &c.edits {
550 
                if let Edit::Replace { old, new, .. } = e {
551 
                    for b in [old, new].into_iter().flatten() {
552 
                        if !self.store.has(b) {
553 
                            self.register_lazy(b, remote)?;
554 
                            n += 1;
555 
                        }
556 
                    }
557 
                }
558 
            }
559 
        }
560 
        Ok(n)
561 
    }
562
563 
    /// Every head this repository knows: bookmarks, remote tracking, working copy.
564 
    fn known_heads(&self, view: &View) -> Result<Vec<ChangeHash>> {
565 
        let mut have: BTreeSet<ChangeHash> = BTreeSet::new();
566 
        for st in view.bookmarks.values().chain(view.remotes.values().flat_map(|b| b.values())) {
567 
            if let Ok(s) = self.store.get_state(st) {
568 
                have.extend(s.heads);
569 
            }
570 
        }
571 
        have.extend(view.workspaces.values().copied());
572 
        Ok(have.into_iter().collect())
573 
    }
574
575 
    /// Fetch every bookmark of a remote into `remotes/<name>/bookmarks/*` (spec §10.2).
576 
    pub fn fetch(&self, remote_name: &str) -> Result<FetchReport> {
577 
        let remote = self.open_named_remote(remote_name)?;
578 
        if remote.repo_id()? != self.id()? {
579 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
580 
        }
581 
        let resp = remote.refs()?;
582 
        // Trust policy (spec §14.5). Adopt the remote's policy when it is newer
583 
        // and signed by roots we trust, or on first contact. A remote that
584 
        // once presented a policy may never present none or an older one:
585 
        // that is a downgrade. A remote that never presented one is
586 
        // unverified, and this fetch is checked only as far as possible.
587 
        let local_policy = self.current_policy()?.map(|(_, sp)| sp.policy);
588 
        let seen = self.remote_policy_serial(remote_name);
589 
        let mut unverified = false;
590 
        match &resp.policy {
591 
            Some(sp) => {
592 
                if seen.is_some_and(|s| sp.policy.serial < s) {
593 
                    return fail(format!("{remote_name} presents policy serial {} but presented {} before: refusing the downgrade", sp.policy.serial, seen.unwrap()));
594 
                }
595 
                match &local_policy {
596 
                    Some(l) if sp.policy.serial < l.serial => {}
597 
                    Some(l) if sp.policy.serial == l.serial => {
598 
                        if sp.policy.hash() != l.hash() {
599 
                            return fail(format!("{remote_name} presents a different policy with the same serial {}", l.serial));
600 
                        }
601 
                    }
602 
                    _ => {
603 
                        self.adopt_policy_chain(&resp.history, sp, &format!("oxy fetch {remote_name}")).map_err(|e| RepoError::Msg(format!("policy from {remote_name}: {e}")))?;
604 
                    }
605 
                }
606 
                self.record_policy_serial(remote_name, sp.policy.serial)?;
607 
            }
608 
            None => {
609 
                if seen.is_some() {
610 
                    return fail(format!("{remote_name} presented a policy before but has none now: refusing the downgrade"));
611 
                }
612 
                unverified = true;
613 
            }
614 
        }
615 
        let policy = if unverified { None } else { self.current_policy()?.map(|(_, sp)| sp.policy) };
616 
        let (op_ref, op) = self.head_op()?;
617 
        let mut view = op.view.clone();
618 
        let have = self.known_heads(&view)?;
619 
        let mut report = Vec::new();
620 
        let max_blob = self.config.max_blob;
621 
        for r in resp.refs {
622 
            let needed = remote.negotiate(&have, &r.heads)?;
623 
            let bundle = remote.fetch(&needed, max_blob)?;
624 
            // Changes are not individually re-verified here: the bookmark's
625 
            // attestation (checked below) binds its whole state, and the
626 
            // receiver of the push verified the added changes at that time.
627 
            let imported = self.import_bundle(&bundle, false)?;
628 
            if max_blob.is_some() {
629 
                self.register_missing_blobs(&imported, remote_name)?;
630 
            }
631 
            for h in &r.heads {
632 
                if !self.store.has(h) {
633 
                    return fail(format!("remote did not send head {}", h.short(12)));
634 
                }
635 
            }
636 
            let state = self.store.put_state(&StateObject::new(r.heads.clone()))?;
637 
            if state != r.state {
638 
                return fail(format!("remote state {} does not match its heads", r.state.short(12)));
639 
            }
640 
            if let Some(p) = &policy {
641 
                let Some(sa) = &r.attestation else {
642 
                    return fail(format!("{remote_name}/{} has no attestation, which its policy requires", r.name));
643 
                };
644 
                let signer = sa.sigs.first().map(|s| s.key).ok_or_else(|| RepoError::Msg("attestation carries no signature".into()))?;
645 
                if !p.authorizes(&signer, &r.name) {
646 
                    return fail(format!("{remote_name}/{}: attested by {}, which the policy does not authorize", r.name, signer.short(12)));
647 
                }
648 
            }
649 
            if let Some(sa) = &r.attestation {
650 
                let AttestBody::Ref { old_state, new_state, .. } = &sa.attest.body else {
651 
                    return fail("remote sent a non-ref attestation for a bookmark");
652 
                };
653 
                let (old_state, new_state) = (*old_state, *new_state);
654 
                let serial = self
655 
                    .check_ref_attest(sa, &r.name, &old_state, &new_state, self.last_seen_serial(remote_name, &r.name), true)
656 
                    .map_err(|e| RepoError::Msg(format!("attestation for {}/{}: {e}", remote_name, r.name)))?;
657 
                if new_state != r.state {
658 
                    return fail(format!("attestation for {}/{} does not cover its current state", remote_name, r.name));
659 
                }
660 
                let ar = self.store.put_attest(&sa.attest)?;
661 
                for sig in &sa.sigs {
662 
                    self.store.put_signature(&ar, sig)?;
663 
                }
664 
                self.record_serial(remote_name, &r.name, serial)?;
665 
            }
666 
            view.remotes.entry(remote_name.to_string()).or_default().insert(r.name.clone(), state);
667 
            report.push((r.name, r.heads, imported.len()));
668 
        }
669 
        let mut new_tags = 0;
670 
        for t in &resp.tags {
671 
            if view.tags.contains_key(&t.name) {
672 
                continue;
673 
            }
674 
            // The tag's changes must be here: fetch them if the bookmarks did not bring them.
675 
            let missing: Vec<ChangeHash> = t.heads.iter().filter(|h| !self.store.has(h)).copied().collect();
676 
            if !missing.is_empty() {
677 
                let needed = remote.negotiate(&self.known_heads(&view)?, &missing)?;
678 
                let bundle = remote.fetch(&needed, max_blob)?;
679 
                self.import_bundle(&bundle, false)?;
680 
            }
681 
            self.store.put_state(&StateObject::new(t.heads.clone()))?;
682 
            self.adopt_tag(&mut view, t, policy.as_ref()).map_err(|e| RepoError::Msg(format!("{remote_name} {}: {e}", t.name)))?;
683 
            new_tags += 1;
684 
        }
685 
        if view != op.view {
686 
            self.record_op(&[op_ref], &format!("oxy fetch {remote_name}"), view)?;
687 
        }
688 
        let _ = self.run_hook(
689 
            "post-fetch",
690 
            &format!(
691 
                "{{\"event\":\"post-fetch\",\"remote\":{},\"bookmarks\":{}}}",
692 
                json_str(remote_name),
693 
                json_array(report.iter().map(|(n, heads, _)| format!("{{\"name\":{},\"heads\":{}}}", json_str(n), json_array(heads.iter().map(|h| json_str(&h.to_hex()))))))
694 
            ),
695 
        );
696 
        Ok(FetchReport { refs: report, unverified, new_tags })
697 
    }
698
699 
    /// Shallow fetch of the remote's bookmark: its checkpoint as our base,
700 
    /// the changes within `depth` steps of its heads, and the boundary below.
701 
    pub fn fetch_shallow(&self, remote_name: &str, depth: u32) -> Result<usize> {
702 
        let remote = self.open_named_remote(remote_name)?;
703 
        if remote.repo_id()? != self.id()? {
704 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
705 
        }
706 
        let resp = remote.refs()?;
707 
        let bookmark = self.config.bookmark.clone();
708 
        if let Some(sp) = &resp.policy {
709 
            self.adopt_policy_chain(&resp.history, sp, "oxy clone --depth").map_err(|e| RepoError::Msg(format!("policy from {remote_name}: {e}")))?;
710 
            self.record_policy_serial(remote_name, sp.policy.serial)?;
711 
        }
712 
        let Some(r) = resp.refs.into_iter().find(|r| r.name == bookmark) else {
713 
            return fail(format!("{remote_name} has no bookmark {bookmark:?}"));
714 
        };
715 
        if r.heads.is_empty() {
716 
            return Ok(0);
717 
        }
718 
        // Base: the remote's checkpoint of exactly these heads.
719 
        let cp_bundle = remote.checkpoint(&r.heads)?;
720 
        let mut cp_ref = None;
721 
        for (ty, body) in &cp_bundle.objects {
722 
            let put = self.store.put(*ty, body)?;
723 
            if *ty == ObjectType::Checkpoint {
724 
                cp_ref = Some(put);
725 
            }
726 
        }
727 
        let Some(cp_ref) = cp_ref else { return fail(format!("{remote_name} sent no checkpoint")) };
728 
        self.install_checkpoint(&bookmark, &cp_ref)?;
729 
        // History window.
730 
        let wanted = remote.shallow(&r.heads, depth)?;
731 
        let bundle = remote.fetch(&wanted, self.config.max_blob)?;
732 
        let imported = self.import_bundle_shallow(&bundle, false)?;
733 
        if self.config.max_blob.is_some() {
734 
            self.register_missing_blobs(&imported, remote_name)?;
735 
        }
736 
        self.refresh_boundary(&imported)?;
737 
        if let Some(sa) = &r.attestation {
738 
            let ar = self.store.put_attest(&sa.attest)?;
739 
            for sig in &sa.sigs {
740 
                self.store.put_signature(&ar, sig)?;
741 
            }
742 
            if let AttestBody::Ref { serial, .. } = sa.attest.body {
743 
                self.record_serial(remote_name, &r.name, serial)?;
744 
            }
745 
        }
746 
        let state = self.store.put_state(&StateObject::new(r.heads.clone()))?;
747 
        let (op_ref, op) = self.head_op()?;
748 
        let mut view = op.view.clone();
749 
        view.remotes.entry(remote_name.to_string()).or_default().insert(r.name.clone(), state);
750 
        self.record_op(&[op_ref], &format!("oxy fetch {remote_name} --depth {depth}"), view)?;
751 
        Ok(imported.len())
752 
    }
753
754 
    /// Fetch, then take the union of the local bookmark's state with the
755 
    /// remote's: no merge change, conflicts become reified (spec §9.4).
756 
    pub fn pull(&self, remote_name: &str) -> Result<PullReport> {
757 
        self.fetch(remote_name)?;
758 
        let (op_ref, op) = self.head_op()?;
759 
        let bookmark = self.config.bookmark.clone();
760 
        let local = self.heads_of(&op.view, &bookmark)?;
761 
        let Some(remote_state) = op.view.remotes.get(remote_name).and_then(|b| b.get(&bookmark)).copied() else {
762 
            return Ok(PullReport { heads: local, changed: false, checked_out: false });
763 
        };
764 
        let remote_heads = self.store.get_state(&remote_state)?.heads;
765 
        let mut all = local.clone();
766 
        all.extend(remote_heads);
767 
        let st = self.load_state(&all)?;
768 
        let mut heads = st.maximal(&all);
769 
        heads.sort();
770 
        let mut sorted_local = local.clone();
771 
        sorted_local.sort();
772 
        if heads == sorted_local {
773 
            return Ok(PullReport { heads, changed: false, checked_out: false });
774 
        }
775 
        let mut view = op.view.clone();
776 
        view.bookmarks.insert(bookmark.clone(), self.store.put_state(&StateObject::new(heads.clone()))?);
777 
        self.record_op(&[op_ref], &format!("oxy pull {remote_name}"), view)?;
778 
        // Follow along if the working copy was clean and on the old heads.
779 
        let snap = self.snapshot("oxy pull")?;
780 
        let clean = snap.wc.tree_ops.is_empty() && snap.wc.edits.is_empty();
781 
        let mut base = snap.base.maximal(&snap.wc.deps);
782 
        base.sort();
783 
        let mut checked_out = false;
784 
        if clean && base == sorted_local {
785 
            self.checkout(&heads, false, "oxy pull (checkout)")?;
786 
            checked_out = true;
787 
        }
788 
        Ok(PullReport { heads, changed: true, checked_out })
789 
    }
790
791 
    /// Push the current bookmark (spec §16.3), sealing this author's unsigned
792 
    /// changes and attesting the reference when a key is available.
793 
    pub fn push(&self, remote_name: &str, force: bool) -> Result<Vec<RefResult>> {
794 
        let (op_ref, op) = self.head_op()?;
795 
        let bookmark = self.config.bookmark.clone();
796 
        let local_heads = self.heads_of(&op.view, &bookmark)?;
797 
        // pre-push hook: may veto before the remote is contacted.
798 
        self.run_hook(
799 
            "pre-push",
800 
            &format!("{{\"event\":\"pre-push\",\"remote\":{},\"bookmark\":{},\"heads\":{}}}", json_str(remote_name), json_str(&bookmark), json_array(local_heads.iter().map(|h| json_str(&h.to_hex())))),
801 
        )?;
802 
        let remote = self.open_named_remote(remote_name)?;
803 
        if remote.repo_id()? != self.id()? {
804 
            return fail(format!("remote {remote_name:?} is a different repository (repository IDs differ)"));
805 
        }
806 
        let resp = remote.refs()?;
807 
        let local_policy = self.current_policy()?.map(|(_, sp)| sp);
808 
        let resp_policy_serial = resp.policy.as_ref().map(|p| p.policy.serial);
809 
        let policy_to_send = match (&local_policy, &resp.policy) {
810 
            (Some(l), Some(r)) if l.policy.serial > r.policy.serial => Some(l.clone()),
811 
            (Some(l), None) => Some(l.clone()),
812 
            (Some(l), Some(r)) if l.policy.serial < r.policy.serial => {
813 
                return fail(format!("{remote_name} has a newer policy (serial {}); fetch first", r.policy.serial));
814 
            }
815 
            _ => None,
816 
        };
817 
        let remote_has_policy = resp.policy.is_some() || policy_to_send.is_some();
818 
        if remote_has_policy && self.secret_key()?.is_none() {
819 
            return fail(format!("{remote_name} enforces a trust policy; pushing needs an identity (`oxy identity create`)"));
820 
        }
821 
        let remote_tags: BTreeSet<String> = resp.tags.iter().map(|t| t.name.clone()).collect();
822 
        let tags_to_send: Vec<crate::protocol::TagRef> = self.tag_refs()?.into_iter().filter(|t| !remote_tags.contains(&t.name)).collect();
823 
        let refs = resp.refs;
824 
        let empty = self.store.put_state(&StateObject::new(vec![]))?;
825 
        let (remote_state, remote_heads, last_serial) = match refs.iter().find(|r| r.name == bookmark) {
826 
            Some(r) => (r.state, r.heads.clone(), r.last_serial),
827 
            None => (empty, vec![], None),
828 
        };
829 
        let new_state = self.store.put_state(&StateObject::new(local_heads.clone()))?;
830 
        // A push that carries a policy re-attests the bookmark even when its
831 
        // state is unchanged, so the current attestation is always by a key
832 
        // the current policy authorizes (a revoked key's attestation would
833 
        // otherwise be refused by every later fetch).
834 
        if new_state == remote_state && policy_to_send.is_none() && tags_to_send.is_empty() {
835 
            return Ok(vec![RefResult { name: bookmark, ok: true, reason: "already up to date".into() }]);
836 
        }
837 
        for h in &remote_heads {
838 
            if !self.store.has(h) {
839 
                return fail(format!("the remote has change {} which you do not; pull first", h.short(12)));
840 
            }
841 
        }
842 
        if !force {
843 
            let closure = self.closure_in_store(&local_heads)?;
844 
            if let Some(h) = remote_heads.iter().find(|h| !closure.contains(h)) {
845 
                return fail(format!("not a fast-forward: remote head {} is not in your state; pull first or use --force", h.short(12)));
846 
            }
847 
        }
848 
        let to_send = self.negotiate(&remote_heads, &local_heads)?;
849 
        let mut bundle = self.bundle_for(&to_send)?;
850 
        let key = self.secret_key()?.map(|(k, _)| k);
851 
        if let Some(key) = key {
852 
            // Seal this author's changes that carry no valid authenticator.
853 
            let mut unsigned = Vec::new();
854 
            for h in &to_send {
855 
                let c = self.store.get_change(h)?;
856 
                if c.author == key && !matches!(self.authenticate_change(h)?, SignatureStatus::Valid { .. }) {
857 
                    unsigned.push(*h);
858 
                }
859 
            }
860 
            for chunk in unsigned.chunks(crate::attest::MAX_SEAL_HASHES) {
861 
                let sa = self.sign_attest(&Attest::seal(self.id()?, chunk.to_vec()))?;
862 
                bundle.attests.push(sa);
863 
            }
864 
            bundle = self.bundle_for(&to_send)?;
865 
        }
866 
        bundle.objects.push((ObjectType::State, StateObject::new(local_heads.clone()).encode()));
867 
        let attestation = match key {
868 
            Some(_) => Some(self.sign_attest(&Attest {
869 
                repo: self.id()?,
870 
                hlc: Hlc::now(),
871 
                body: AttestBody::Ref { name: bookmark.clone(), old_state: remote_state, new_state, serial: last_serial.unwrap_or(0) + 1 },
872 
            })?),
873 
            None => None,
874 
        };
875 
        let serial = attestation.as_ref().and_then(|a| match a.attest.body {
876 
            AttestBody::Ref { serial, .. } => Some(serial),
877 
            _ => None,
878 
        });
879 
        let sent_serial = policy_to_send.as_ref().map(|p| p.policy.serial);
880 
        // Tag states must be present on the remote: bundle their changes too.
881 
        for t in &tags_to_send {
882 
            let extra = self.negotiate(&remote_heads, &t.heads)?;
883 
            let extra: Vec<ChangeHash> = extra.into_iter().filter(|h| !to_send.contains(h)).collect();
884 
            if !extra.is_empty() {
885 
                let more = self.bundle_for(&extra)?;
886 
                bundle.changes.extend(more.changes);
887 
                bundle.attests.extend(more.attests);
888 
                bundle.objects.extend(more.objects);
889 
            }
890 
            bundle.objects.push((ObjectType::State, StateObject::new(t.heads.clone()).encode()));
891 
        }
892 
        if let Some(l) = &policy_to_send {
893 
            let remote_serial = resp_policy_serial;
894 
            bundle.policies = self.policy_history()?.into_iter().filter(|sp| remote_serial.is_none_or(|r| sp.policy.serial > r) && sp.policy.serial < l.policy.serial).collect();
895 
        }
896 
        let results = remote.push(bundle, vec![RefUpdate { name: bookmark.clone(), old_state: remote_state, new_state, force, attestation }], policy_to_send, tags_to_send)?;
897 
        if let (Some(serial), true) = (sent_serial, results.iter().any(|r| r.ok && r.name == "policy")) {
898 
            self.record_policy_serial(remote_name, serial)?;
899 
        }
900 
        if results.iter().any(|r| r.ok && r.name == bookmark) {
901 
            let mut view = op.view.clone();
902 
            view.remotes.entry(remote_name.to_string()).or_default().insert(bookmark.clone(), new_state);
903 
            self.record_op(&[op_ref], &format!("oxy push {remote_name}"), view)?;
904 
            if let Some(s) = serial {
905 
                self.record_serial(remote_name, &bookmark, s)?;
906 
            }
907 
        }
908 
        Ok(results)
909 
    }
910
911 
    /// Clone a remote into `dest`: same repository ID, `origin` remote,
912 
    /// bookmark set to the remote's, working copy checked out.
913 
    pub fn clone(url: &str, dest: &Path) -> Result<Repo> {
914 
        Self::clone_with(url, dest, None, &[])
915 
    }
916
917 
    /// Clone, leaving blobs above `max_blob` bytes to be fetched on first
918 
    /// read, and materializing only `sparse` paths (which implies lazy blobs
919 
    /// unless a size is given, so out-of-scope binaries are never fetched).
920 
    pub fn clone_with(url: &str, dest: &Path, max_blob: Option<u64>, sparse: &[String]) -> Result<Repo> {
921 
        Self::clone_full(url, dest, max_blob, sparse, None)
922 
    }
923
924 
    /// Shallow clone (spec §17): a checkpoint of the bookmark's heads plus the
925 
    /// changes within `depth` steps of them; the rest is the boundary.
926 
    pub fn clone_shallow(url: &str, dest: &Path, depth: u32, max_blob: Option<u64>, sparse: &[String]) -> Result<Repo> {
927 
        Self::clone_full(url, dest, max_blob, sparse, Some(depth))
928 
    }
929
930 
    fn clone_full(url: &str, dest: &Path, max_blob: Option<u64>, sparse: &[String], depth: Option<u32>) -> Result<Repo> {
931 
        let options = RemoteOptions {
932 
            token: std::env::var("OXY_TOKEN").ok(),
933 
            ca: std::env::var("OXY_CA").ok().map(PathBuf::from),
934 
        };
935 
        let remote = open_remote(url, &options)?;
936 
        let id = remote.repo_id()?;
937 
        let mut repo = Repo::init_with_id(dest, id)?;
938 
        repo.config.set("remote.origin.url", url)?;
939 
        if let Some(m) = max_blob {
940 
            repo.config.set("filter.max-blob", &m.to_string())?;
941 
        } else if !sparse.is_empty() {
942 
            repo.config.set("filter.max-blob", "0")?;
943 
        }
944 
        if !sparse.is_empty() {
945 
            repo.config.set("filter.paths", &sparse.join(","))?;
946 
        }
947 
        repo.save_config()?;
948 
        if let Some(depth) = depth {
949 
            repo.fetch_shallow("origin", depth)?;
950 
        } else {
951 
            repo.fetch("origin")?;
952 
        }
953 
        let (op_ref, op) = repo.head_op()?;
954 
        let bookmark = repo.config.bookmark.clone();
955 
        if let Some(state) = op.view.remotes.get("origin").and_then(|b| b.get(&bookmark)).copied() {
956 
            let heads = repo.store.get_state(&state)?.heads;
957 
            let mut view = op.view.clone();
958 
            view.bookmarks.insert(bookmark, state);
959 
            repo.record_op(&[op_ref], &format!("oxy clone {url}"), view)?;
960 
            repo.checkout(&heads, false, "oxy clone (checkout)")?;
961 
        }
962 
        Ok(repo)
963 
    }
964 
}