v0.3.6-pre.005

crates/ksp-job-backfill-lib/src/constants.rs

@@ -0,0 +1,7 @@
+// file: crates/ksp-job-backfill-lib/src/constants.rs
+// version: 1
+
+//! Backfill runtime-owned constants.
+
+/// Owning tracing target for the concrete bounded RAW backfill runtime.
+pub(crate) const TRACING_TARGET: &str = "ksp-job-backfill-lib";

crates/ksp-job-backfill-lib/src/discovery.rs

@@ -0,0 +1,443 @@
+// file: crates/ksp-job-backfill-lib/src/discovery.rs
+// version: 1
+
+/// Network-scoped identity of one discovered transaction candidate before canonical signature decoding.
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct BackfillCandidateIdentity {
+    network: ksp_store_lib::RawNetworkId,
+    signature: crate::BackfillSignature,
+}
+
+impl BackfillCandidateIdentity {
+    /// Creates one candidate identity from its logical network and encoded transaction signature.
+    #[must_use]
+    pub fn new(network: ksp_store_lib::RawNetworkId, signature: crate::BackfillSignature) -> Self {
+        return Self { network, signature };
+    }
+
+    /// Returns the logical network that scopes signature uniqueness.
+    #[must_use]
+    pub const fn network(&self) -> &ksp_store_lib::RawNetworkId {
+        return &self.network;
+    }
+
+    /// Returns the validated encoded transaction signature.
+    #[must_use]
+    pub const fn signature(&self) -> &crate::BackfillSignature {
+        return &self.signature;
+    }
+}
+
+/// One deterministic transaction candidate produced by bounded discovery.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct BackfillCandidate {
+    identity: BackfillCandidateIdentity,
+    discovered_slot: std::option::Option<u64>,
+}
+
+impl BackfillCandidate {
+    /// Creates one candidate from a network-scoped identity and optional discovery slot.
+    #[must_use]
+    pub fn new(identity: BackfillCandidateIdentity, discovered_slot: std::option::Option<u64>) -> Self {
+        return Self { identity, discovered_slot };
+    }
+
+    /// Returns the network-scoped candidate identity.
+    #[must_use]
+    pub const fn identity(&self) -> &BackfillCandidateIdentity {
+        return &self.identity;
+    }
+
+    /// Returns the slot reported by address discovery, when one was available.
+    #[must_use]
+    pub const fn discovered_slot(&self) -> std::option::Option<u64> {
+        return self.discovered_slot;
+    }
+}
+
+/// Reason bounded candidate discovery stopped.
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub enum BackfillDiscoveryBoundary {
+    /// Explicit signatures required no RPC pagination.
+    ExplicitInput,
+    /// The caller's requested candidate limit was satisfied.
+    CandidateLimit,
+    /// The RPC returned a short or empty page, reaching the bounded remote history boundary.
+    RpcBoundary,
+    /// The maximum page count was exhausted before the requested address window completed.
+    PageLimit,
+    /// An `AfterAddress` scan exhausted its page bound before the exclusive anchor boundary was reached.
+    AfterAnchorNotReached,
+}
+
+impl BackfillDiscoveryBoundary {
+    /// Returns the stable diagnostic code for this boundary.
+    #[must_use]
+    pub const fn code(self) -> &'static str {
+        return match self {
+            Self::ExplicitInput => "explicit_input",
+            Self::CandidateLimit => "candidate_limit",
+            Self::RpcBoundary => "rpc_boundary",
+            Self::PageLimit => "page_limit",
+            Self::AfterAnchorNotReached => "after_anchor_not_reached",
+        };
+    }
+
+    /// Returns whether the discovery result is partial and must not advance a future checkpoint beyond the unresolved gap.
+    #[must_use]
+    pub const fn is_partial(self) -> bool {
+        return matches!(self, Self::PageLimit | Self::AfterAnchorNotReached);
+    }
+}
+
+/// Complete bounded output of one candidate discovery pass.
+pub struct BackfillDiscovery {
+    network: ksp_store_lib::RawNetworkId,
+    scope_fingerprint: crate::BackfillScopeFingerprint,
+    candidates: std::vec::Vec<BackfillCandidate>,
+    pages_fetched: usize,
+    boundary: BackfillDiscoveryBoundary,
+}
+
+impl BackfillDiscovery {
+    /// Returns the logical network shared by every candidate identity.
+    #[must_use]
+    pub const fn network(&self) -> &ksp_store_lib::RawNetworkId {
+        return &self.network;
+    }
+
+    /// Returns the semantic scope fingerprint copied from the validated request.
+    #[must_use]
+    pub const fn scope_fingerprint(&self) -> crate::BackfillScopeFingerprint {
+        return self.scope_fingerprint;
+    }
+
+    /// Returns discovered candidates in deterministic processing order.
+    #[must_use]
+    pub fn candidates(&self) -> &[BackfillCandidate] {
+        return self.candidates.as_slice();
+    }
+
+    /// Returns the number of `getSignaturesForAddress` pages fetched by this pass.
+    #[must_use]
+    pub const fn pages_fetched(&self) -> usize {
+        return self.pages_fetched;
+    }
+
+    /// Returns the reason discovery stopped.
+    #[must_use]
+    pub const fn boundary(&self) -> BackfillDiscoveryBoundary {
+        return self.boundary;
+    }
+
+    /// Returns whether the bounded pass stopped before a complete requested discovery window was proven.
+    #[must_use]
+    pub const fn is_partial(&self) -> bool {
+        return self.boundary.is_partial();
+    }
+}
+
+impl std::fmt::Debug for BackfillDiscovery {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        return formatter
+            .debug_struct("BackfillDiscovery")
+            .field("network", &self.network)
+            .field("scope_fingerprint", &self.scope_fingerprint)
+            .field("candidate_count", &self.candidates.len())
+            .field("pages_fetched", &self.pages_fetched)
+            .field("boundary", &self.boundary)
+            .finish();
+    }
+}
+
+struct SignaturePageEntry {
+    signature: std::string::String,
+    slot: u64,
+}
+
+type SignaturePageFuture<'a> = std::pin::Pin<std::boxed::Box<dyn std::future::Future<Output = ksp_core_lib::Result<std::vec::Vec<SignaturePageEntry>>> + 'a>>;
+
+trait SignaturePageSource {
+    fn fetch_signature_page<'a>(
+        &'a self,
+        role: &'a ksp_onchain_transport_lib::HttpRoleName,
+        address: &'a ksp_core_lib::Pubkey,
+        config: ksp_onchain_transport_lib::SolanaSignaturesForAddressConfig,
+    ) -> SignaturePageFuture<'a>;
+}
+
+impl SignaturePageSource for ksp_onchain_transport_lib::HttpTransportPool {
+    fn fetch_signature_page<'a>(
+        &'a self,
+        role: &'a ksp_onchain_transport_lib::HttpRoleName,
+        address: &'a ksp_core_lib::Pubkey,
+        config: ksp_onchain_transport_lib::SolanaSignaturesForAddressConfig,
+    ) -> SignaturePageFuture<'a> {
+        return std::boxed::Box::pin(async move {
+            let result = self.get_signatures_for_address(role, address, std::option::Option::Some(&config)).await;
+            let infos = match result {
+                std::result::Result::Ok(infos) => infos,
+                std::result::Result::Err(error) => return std::result::Result::Err(error),
+            };
+            let mut entries = std::vec::Vec::with_capacity(infos.len());
+            for info in infos {
+                entries.push(SignaturePageEntry { signature: info.signature().to_owned(), slot: info.slot() });
+            }
+            return std::result::Result::Ok(entries);
+        });
+    }
+}
+
+/// Discovers one bounded deterministic candidate set using only the typed KSP Transport wrapper.
+///
+/// Provider, endpoint and protocol selection remain entirely owned by Transport. Candidate identity
+/// is scoped only by the request network plus transaction signature.
+pub async fn discover_backfill_candidates(
+    transport: &ksp_onchain_transport_lib::HttpTransportPool,
+    request: &crate::BackfillRequest,
+) -> ksp_core_lib::Result<BackfillDiscovery> {
+    ksp_logging_lib::debug!(
+        target: crate::TRACING_TARGET,
+        job_id = request.job_id().as_str(),
+        network = request.network().as_str(),
+        scope = request.scope().kind().code(),
+        page_size = request.page_size(),
+        max_pages = request.max_pages(),
+        max_candidates = request.max_candidates(),
+        "starting bounded Backfill candidate discovery"
+    );
+    let result = discover_with_source(transport, request).await;
+    if let std::result::Result::Ok(discovery) = &result {
+        ksp_logging_lib::debug!(
+            target: crate::TRACING_TARGET,
+            job_id = request.job_id().as_str(),
+            network = request.network().as_str(),
+            scope = request.scope().kind().code(),
+            pages_fetched = discovery.pages_fetched(),
+            candidate_count = discovery.candidates().len(),
+            boundary = discovery.boundary().code(),
+            partial = discovery.is_partial(),
+            "completed bounded Backfill candidate discovery"
+        );
+    }
+    return result;
+}
+
+async fn discover_with_source<S>(source: &S, request: &crate::BackfillRequest) -> ksp_core_lib::Result<BackfillDiscovery>
+where
+    S: SignaturePageSource,
+{
+    return match request.scope().kind() {
+        crate::BackfillScopeKind::ExplicitSignatures => discover_explicit(request),
+        crate::BackfillScopeKind::LatestAddress | crate::BackfillScopeKind::BeforeAddress => discover_older(source, request).await,
+        crate::BackfillScopeKind::AfterAddress => discover_after(source, request).await,
+    };
+}
+
+fn discover_explicit(request: &crate::BackfillRequest) -> ksp_core_lib::Result<BackfillDiscovery> {
+    let signatures = match request.scope().signatures() {
+        std::option::Option::Some(signatures) => signatures,
+        std::option::Option::None => return std::result::Result::Err(discovery_invalid("scope.signatures")),
+    };
+    let mut candidates = std::vec::Vec::with_capacity(signatures.len());
+    for signature in signatures {
+        let identity = BackfillCandidateIdentity::new(request.network().clone(), signature.clone());
+        candidates.push(BackfillCandidate::new(identity, std::option::Option::None));
+    }
+    return std::result::Result::Ok(BackfillDiscovery {
+        network: request.network().clone(),
+        scope_fingerprint: request.scope_fingerprint(),
+        candidates,
+        pages_fetched: 0,
+        boundary: BackfillDiscoveryBoundary::ExplicitInput,
+    });
+}
+
+async fn discover_older<S>(source: &S, request: &crate::BackfillRequest) -> ksp_core_lib::Result<BackfillDiscovery>
+where
+    S: SignaturePageSource,
+{
+    let address = match request.scope().address() {
+        std::option::Option::Some(address) => address,
+        std::option::Option::None => return std::result::Result::Err(discovery_invalid("scope.address")),
+    };
+    let mut before = match request.scope().kind() {
+        crate::BackfillScopeKind::BeforeAddress => request.scope().anchor().map(|value| value.as_str().to_owned()),
+        crate::BackfillScopeKind::LatestAddress => std::option::Option::None,
+        crate::BackfillScopeKind::AfterAddress | crate::BackfillScopeKind::ExplicitSignatures => {
+            return std::result::Result::Err(discovery_invalid("scope.kind"));
+        },
+    };
+    let mut candidates = std::vec::Vec::with_capacity(request.max_candidates());
+    let mut seen = std::collections::HashSet::<crate::BackfillSignature>::with_capacity(request.max_candidates());
+    let mut pages_fetched = 0_usize;
+    let boundary = loop {
+        if candidates.len() >= request.max_candidates() {
+            break BackfillDiscoveryBoundary::CandidateLimit;
+        }
+        if pages_fetched >= request.max_pages() {
+            break BackfillDiscoveryBoundary::PageLimit;
+        }
+        let remaining = request.max_candidates() - candidates.len();
+        let page_limit = std::cmp::min(request.page_size(), remaining);
+        let config = ksp_onchain_transport_lib::SolanaSignaturesForAddressConfig::new(
+            before.clone(),
+            std::option::Option::None,
+            std::option::Option::Some(page_limit),
+            std::option::Option::Some(request.commitment().transport()),
+            request.min_context_slot(),
+        );
+        let page_result = source.fetch_signature_page(request.role(), address, config).await;
+        let page = match page_result {
+            std::result::Result::Ok(page) => page,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        pages_fetched += 1;
+        if page.len() > page_limit {
+            return std::result::Result::Err(discovery_invalid("page.length"));
+        }
+        let page_len = page.len();
+        let next_before = match page.last() {
+            std::option::Option::Some(entry) => {
+                let signature_result = validated_signature(entry.signature.as_str());
+                match signature_result {
+                    std::result::Result::Ok(signature) => std::option::Option::Some(signature),
+                    std::result::Result::Err(error) => return std::result::Result::Err(error),
+                }
+            },
+            std::option::Option::None => std::option::Option::None,
+        };
+        for entry in page {
+            let signature_result = validated_signature(entry.signature.as_str());
+            let signature = match signature_result {
+                std::result::Result::Ok(signature) => signature,
+                std::result::Result::Err(error) => return std::result::Result::Err(error),
+            };
+            if seen.insert(signature.clone()) {
+                let identity = BackfillCandidateIdentity::new(request.network().clone(), signature);
+                candidates.push(BackfillCandidate::new(identity, std::option::Option::Some(entry.slot)));
+                if candidates.len() >= request.max_candidates() {
+                    break;
+                }
+            }
+        }
+        if page_len < page_limit {
+            break BackfillDiscoveryBoundary::RpcBoundary;
+        }
+        let next_before = match next_before {
+            std::option::Option::Some(next_before) => next_before,
+            std::option::Option::None => break BackfillDiscoveryBoundary::RpcBoundary,
+        };
+        if before.as_deref() == std::option::Option::Some(next_before.as_str()) {
+            return std::result::Result::Err(discovery_stalled());
+        }
+        before = std::option::Option::Some(next_before.as_str().to_owned());
+    };
+    return std::result::Result::Ok(BackfillDiscovery {
+        network: request.network().clone(),
+        scope_fingerprint: request.scope_fingerprint(),
+        candidates,
+        pages_fetched,
+        boundary,
+    });
+}
+
+async fn discover_after<S>(source: &S, request: &crate::BackfillRequest) -> ksp_core_lib::Result<BackfillDiscovery>
+where
+    S: SignaturePageSource,
+{
+    let address = match request.scope().address() {
+        std::option::Option::Some(address) => address,
+        std::option::Option::None => return std::result::Result::Err(discovery_invalid("scope.address")),
+    };
+    let anchor = match request.scope().anchor() {
+        std::option::Option::Some(anchor) => anchor,
+        std::option::Option::None => return std::result::Result::Err(discovery_invalid("scope.anchor")),
+    };
+    let until = anchor.as_str().to_owned();
+    let mut before = std::option::Option::<std::string::String>::None;
+    let mut nearest = std::collections::VecDeque::<BackfillCandidate>::with_capacity(request.max_candidates());
+    let mut seen = std::collections::HashSet::<crate::BackfillSignature>::new();
+    let mut pages_fetched = 0_usize;
+    let boundary = loop {
+        if pages_fetched >= request.max_pages() {
+            break BackfillDiscoveryBoundary::AfterAnchorNotReached;
+        }
+        let config = ksp_onchain_transport_lib::SolanaSignaturesForAddressConfig::new(
+            before.clone(),
+            std::option::Option::Some(until.clone()),
+            std::option::Option::Some(request.page_size()),
+            std::option::Option::Some(request.commitment().transport()),
+            request.min_context_slot(),
+        );
+        let page_result = source.fetch_signature_page(request.role(), address, config).await;
+        let page = match page_result {
+            std::result::Result::Ok(page) => page,
+            std::result::Result::Err(error) => return std::result::Result::Err(error),
+        };
+        pages_fetched += 1;
+        if page.len() > request.page_size() {
+            return std::result::Result::Err(discovery_invalid("page.length"));
+        }
+        let page_len = page.len();
+        let next_before = match page.last() {
+            std::option::Option::Some(entry) => {
+                let signature_result = validated_signature(entry.signature.as_str());
+                match signature_result {
+                    std::result::Result::Ok(signature) => std::option::Option::Some(signature),
+                    std::result::Result::Err(error) => return std::result::Result::Err(error),
+                }
+            },
+            std::option::Option::None => std::option::Option::None,
+        };
+        for entry in page {
+            let signature_result = validated_signature(entry.signature.as_str());
+            let signature = match signature_result {
+                std::result::Result::Ok(signature) => signature,
+                std::result::Result::Err(error) => return std::result::Result::Err(error),
+            };
+            if seen.insert(signature.clone()) {
+                let identity = BackfillCandidateIdentity::new(request.network().clone(), signature);
+                nearest.push_back(BackfillCandidate::new(identity, std::option::Option::Some(entry.slot)));
+                if nearest.len() > request.max_candidates() {
+                    nearest.pop_front();
+                }
+            }
+        }
+        if page_len < request.page_size() {
+            break BackfillDiscoveryBoundary::RpcBoundary;
+        }
+        let next_before = match next_before {
+            std::option::Option::Some(next_before) => next_before,
+            std::option::Option::None => break BackfillDiscoveryBoundary::RpcBoundary,
+        };
+        if before.as_deref() == std::option::Option::Some(next_before.as_str()) {
+            return std::result::Result::Err(discovery_stalled());
+        }
+        before = std::option::Option::Some(next_before.as_str().to_owned());
+    };
+    return std::result::Result::Ok(BackfillDiscovery {
+        network: request.network().clone(),
+        scope_fingerprint: request.scope_fingerprint(),
+        candidates: nearest.into_iter().collect(),
+        pages_fetched,
+        boundary,
+    });
+}
+
+fn validated_signature(value: &str) -> ksp_core_lib::Result<crate::BackfillSignature> {
+    return crate::BackfillSignature::new(value.to_owned());
+}
+
+fn discovery_invalid(field: &'static str) -> ksp_core_lib::Error {
+    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_DISCOVERY_INVALID, "invalid bounded Backfill discovery state").with_context("field", field);
+}
+
+fn discovery_stalled() -> ksp_core_lib::Error {
+    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_DISCOVERY_STALLED, "Backfill discovery cursor did not advance")
+        .with_context("field", "before");
+}
+
+#[cfg(test)]
+#[path = "../unit_tests/discovery.rs"]
+mod tests;

crates/ksp-job-backfill-lib/src/error.rs

@@ -0,0 +1,11 @@
+// file: crates/ksp-job-backfill-lib/src/error.rs
+// version: 1
+
+/// Error code used when a signature page violates a bounded discovery invariant.
+pub const ERROR_CODE_BACKFILL_DISCOVERY_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("job_backfill", "discovery_invalid");
+/// Error code used when paginated discovery cannot advance its exclusive RPC cursor safely.
+pub const ERROR_CODE_BACKFILL_DISCOVERY_STALLED: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("job_backfill", "discovery_stalled");
+/// Error code used when one Backfill request violates its bounded admission contract.
+pub const ERROR_CODE_BACKFILL_REQUEST_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("job_backfill", "request_invalid");
+/// Error code used when one transaction signature text violates the bounded Base58-shape contract.
+pub const ERROR_CODE_BACKFILL_SIGNATURE_INVALID: ksp_core_lib::ErrorCode = ksp_core_lib::ErrorCode::new("job_backfill", "signature_invalid");

crates/ksp-job-backfill-lib/src/lib.rs

@@ -0,0 +1,64 @@
+// file: crates/ksp-job-backfill-lib/src/lib.rs
+// version: 1
+
+#![warn(missing_docs)]
+#![deny(unreachable_pub)]
+#![forbid(unsafe_code)]
+
+//! Concrete bounded historical RAW transaction Backfill foundation.
+//!
+//! This tranche owns explicit admission, network-scoped candidate identity and deterministic
+//! `getSignaturesForAddress` pagination. Transport retains provider/endpoint selection and retry;
+//! Store retains durable idempotence and persistence. RAW conversion, persistence, concurrency,
+//! checkpointing, cancellation and concrete latest-value snapshots are added by later v0.3.6 tranches.
+
+mod constants;
+mod discovery;
+mod error;
+mod request;
+
+/// One deterministic transaction candidate produced by bounded discovery.
+pub use self::discovery::BackfillCandidate;
+/// Network-scoped identity of one discovered transaction candidate before canonical signature decoding.
+pub use self::discovery::BackfillCandidateIdentity;
+/// Complete bounded output of one candidate discovery pass.
+pub use self::discovery::BackfillDiscovery;
+/// Reason bounded candidate discovery stopped.
+pub use self::discovery::BackfillDiscoveryBoundary;
+/// Discovers one bounded deterministic candidate set through the typed KSP Transport wrapper.
+pub use self::discovery::discover_backfill_candidates;
+/// Error code used when a signature page violates a bounded discovery invariant.
+pub use self::error::ERROR_CODE_BACKFILL_DISCOVERY_INVALID;
+/// Error code used when paginated discovery cannot advance its exclusive RPC cursor safely.
+pub use self::error::ERROR_CODE_BACKFILL_DISCOVERY_STALLED;
+/// Error code used when one Backfill request violates its bounded admission contract.
+pub use self::error::ERROR_CODE_BACKFILL_REQUEST_INVALID;
+/// Error code used when one transaction signature text violates the bounded Base58-shape contract.
+pub use self::error::ERROR_CODE_BACKFILL_SIGNATURE_INVALID;
+/// Commitment levels intentionally admitted by the historical Backfill vertical.
+pub use self::request::BackfillCommitment;
+/// Fully explicit bounded request for one historical transaction Backfill Job.
+pub use self::request::BackfillRequest;
+/// Validated bounded discovery scope for one historical Backfill Job.
+pub use self::request::BackfillScope;
+/// Opaque deterministic fingerprint of one semantic Backfill scope.
+pub use self::request::BackfillScopeFingerprint;
+/// Stable category of one bounded Backfill discovery scope.
+pub use self::request::BackfillScopeKind;
+/// Bounded Base58-shaped transaction signature text used before canonical 64-byte decoding.
+pub use self::request::BackfillSignature;
+/// Maximum number of transaction candidates admitted by one bounded Backfill Job.
+pub use self::request::MAX_BACKFILL_CANDIDATES;
+/// Maximum number of concurrent transaction hydrations admitted by one Backfill request.
+pub use self::request::MAX_BACKFILL_HYDRATION_CONCURRENCY;
+/// Maximum number of `getSignaturesForAddress` pages admitted by one address Backfill request.
+pub use self::request::MAX_BACKFILL_PAGES;
+/// Maximum page size admitted for one `getSignaturesForAddress` request.
+pub use self::request::MAX_BACKFILL_PAGE_SIZE;
+/// Maximum Base58 text length possible for one canonical 64-byte Solana signature.
+pub use self::request::MAX_BACKFILL_SIGNATURE_TEXT_BYTES;
+/// Minimum Base58 text length possible for one canonical 64-byte Solana signature.
+pub use self::request::MIN_BACKFILL_SIGNATURE_TEXT_BYTES;
+
+/// Owning tracing target used by the concrete Backfill runtime.
+pub(crate) use self::constants::TRACING_TARGET;

crates/ksp-job-backfill-lib/src/request.rs

@@ -0,0 +1,466 @@
+// file: crates/ksp-job-backfill-lib/src/request.rs
+// version: 1
+
+use sha2::Digest; // rust-rules: trait-import
+
+/// Maximum number of transaction candidates admitted by one bounded Backfill Job.
+pub const MAX_BACKFILL_CANDIDATES: usize = 10_000;
+/// Maximum number of concurrent transaction hydrations admitted by one Backfill request.
+pub const MAX_BACKFILL_HYDRATION_CONCURRENCY: usize = 64;
+/// Maximum number of `getSignaturesForAddress` pages admitted by one address Backfill request.
+pub const MAX_BACKFILL_PAGES: usize = 10_000;
+/// Maximum page size admitted for one `getSignaturesForAddress` request.
+pub const MAX_BACKFILL_PAGE_SIZE: usize = 1_000;
+/// Maximum Base58 text length possible for one canonical 64-byte Solana signature.
+pub const MAX_BACKFILL_SIGNATURE_TEXT_BYTES: usize = 88;
+/// Minimum Base58 text length possible for one canonical 64-byte Solana signature.
+pub const MIN_BACKFILL_SIGNATURE_TEXT_BYTES: usize = 64;
+
+/// Commitment levels intentionally admitted by the historical Backfill vertical.
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub enum BackfillCommitment {
+    /// Read history at Solana `confirmed` commitment.
+    Confirmed,
+    /// Read history at Solana `finalized` commitment.
+    Finalized,
+}
+
+impl BackfillCommitment {
+    /// Returns the stable Backfill commitment code.
+    #[must_use]
+    pub const fn code(self) -> &'static str {
+        return match self {
+            Self::Confirmed => "confirmed",
+            Self::Finalized => "finalized",
+        };
+    }
+
+    /// Maps the narrowed Backfill commitment to the Transport-owned Solana commitment.
+    #[must_use]
+    pub(crate) const fn transport(self) -> ksp_onchain_transport_lib::SolanaCommitment {
+        return match self {
+            Self::Confirmed => ksp_onchain_transport_lib::SolanaCommitment::Confirmed,
+            Self::Finalized => ksp_onchain_transport_lib::SolanaCommitment::Finalized,
+        };
+    }
+}
+
+/// Bounded Base58-shaped transaction signature text used before canonical 64-byte decoding.
+///
+/// This type deliberately validates only the encoded shape required by discovery. Exact decoding
+/// to the Store-owned 64-byte signature is introduced by the RAW conversion tranche.
+#[derive(Clone, Eq, Hash, Ord, PartialEq, PartialOrd)]
+pub struct BackfillSignature(std::string::String);
+
+impl BackfillSignature {
+    /// Creates one bounded Base58-shaped signature text.
+    pub fn new(value: impl std::convert::Into<std::string::String>) -> ksp_core_lib::Result<Self> {
+        let value = value.into();
+        if !valid_signature_text(value.as_str()) {
+            return std::result::Result::Err(signature_error());
+        }
+        return std::result::Result::Ok(Self(value));
+    }
+
+    /// Returns the validated encoded signature text.
+    #[must_use]
+    pub fn as_str(&self) -> &str {
+        return self.0.as_str();
+    }
+}
+
+impl std::fmt::Debug for BackfillSignature {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        return formatter.write_str("BackfillSignature(..)");
+    }
+}
+
+/// Stable category of one bounded Backfill discovery scope.
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub enum BackfillScopeKind {
+    /// Read the current newest address window.
+    LatestAddress,
+    /// Read address history older than one exclusive anchor.
+    BeforeAddress,
+    /// Read the bounded newer window closest to one exclusive anchor.
+    AfterAddress,
+    /// Hydrate an explicit bounded signature list without address discovery.
+    ExplicitSignatures,
+}
+
+impl BackfillScopeKind {
+    /// Returns the stable scope code used by diagnostics and scope fingerprinting.
+    #[must_use]
+    pub const fn code(self) -> &'static str {
+        return match self {
+            Self::LatestAddress => "latest_address",
+            Self::BeforeAddress => "before_address",
+            Self::AfterAddress => "after_address",
+            Self::ExplicitSignatures => "explicit_signatures",
+        };
+    }
+}
+
+#[derive(Clone, Eq, PartialEq)]
+enum BackfillScopeValue {
+    LatestAddress { address: ksp_core_lib::Pubkey },
+    BeforeAddress { address: ksp_core_lib::Pubkey, anchor: BackfillSignature },
+    AfterAddress { address: ksp_core_lib::Pubkey, anchor: BackfillSignature },
+    ExplicitSignatures { signatures: std::vec::Vec<BackfillSignature> },
+}
+
+/// Validated bounded discovery scope for one historical Backfill Job.
+#[derive(Clone, Eq, PartialEq)]
+pub struct BackfillScope {
+    value: BackfillScopeValue,
+}
+
+impl BackfillScope {
+    /// Creates a scope starting at the newest known history for one address.
+    #[must_use]
+    pub const fn latest_address(address: ksp_core_lib::Pubkey) -> Self {
+        return Self { value: BackfillScopeValue::LatestAddress { address } };
+    }
+
+    /// Creates a scope reading history older than one exclusive address anchor.
+    #[must_use]
+    pub fn before_address(address: ksp_core_lib::Pubkey, anchor: BackfillSignature) -> Self {
+        return Self { value: BackfillScopeValue::BeforeAddress { address, anchor } };
+    }
+
+    /// Creates a scope reading the bounded newer history closest to one exclusive address anchor.
+    #[must_use]
+    pub fn after_address(address: ksp_core_lib::Pubkey, anchor: BackfillSignature) -> Self {
+        return Self { value: BackfillScopeValue::AfterAddress { address, anchor } };
+    }
+
+    /// Creates an explicit signature scope with stable first-occurrence deduplication.
+    pub fn explicit_signatures(signatures: std::vec::Vec<BackfillSignature>) -> ksp_core_lib::Result<Self> {
+        if signatures.is_empty() || signatures.len() > crate::MAX_BACKFILL_CANDIDATES {
+            return std::result::Result::Err(request_error("scope.signatures"));
+        }
+        let mut unique = std::vec::Vec::with_capacity(signatures.len());
+        let mut seen = std::collections::HashSet::with_capacity(signatures.len());
+        for signature in signatures {
+            if seen.insert(signature.clone()) {
+                unique.push(signature);
+            }
+        }
+        if unique.is_empty() {
+            return std::result::Result::Err(request_error("scope.signatures"));
+        }
+        return std::result::Result::Ok(Self { value: BackfillScopeValue::ExplicitSignatures { signatures: unique } });
+    }
+
+    /// Returns the stable category of this scope.
+    #[must_use]
+    pub const fn kind(&self) -> BackfillScopeKind {
+        return match &self.value {
+            BackfillScopeValue::LatestAddress { .. } => BackfillScopeKind::LatestAddress,
+            BackfillScopeValue::BeforeAddress { .. } => BackfillScopeKind::BeforeAddress,
+            BackfillScopeValue::AfterAddress { .. } => BackfillScopeKind::AfterAddress,
+            BackfillScopeValue::ExplicitSignatures { .. } => BackfillScopeKind::ExplicitSignatures,
+        };
+    }
+
+    /// Returns the address used by address scopes.
+    #[must_use]
+    pub const fn address(&self) -> std::option::Option<&ksp_core_lib::Pubkey> {
+        return match &self.value {
+            BackfillScopeValue::LatestAddress { address }
+            | BackfillScopeValue::BeforeAddress { address, .. }
+            | BackfillScopeValue::AfterAddress { address, .. } => std::option::Option::Some(address),
+            BackfillScopeValue::ExplicitSignatures { .. } => std::option::Option::None,
+        };
+    }
+
+    /// Returns the exclusive anchor used by before/after scopes.
+    #[must_use]
+    pub const fn anchor(&self) -> std::option::Option<&BackfillSignature> {
+        return match &self.value {
+            BackfillScopeValue::BeforeAddress { anchor, .. } | BackfillScopeValue::AfterAddress { anchor, .. } => std::option::Option::Some(anchor),
+            BackfillScopeValue::LatestAddress { .. } | BackfillScopeValue::ExplicitSignatures { .. } => std::option::Option::None,
+        };
+    }
+
+    /// Returns the stable deduplicated explicit signature list, when this is an explicit scope.
+    #[must_use]
+    pub fn signatures(&self) -> std::option::Option<&[BackfillSignature]> {
+        return match &self.value {
+            BackfillScopeValue::ExplicitSignatures { signatures } => std::option::Option::Some(signatures.as_slice()),
+            BackfillScopeValue::LatestAddress { .. } | BackfillScopeValue::BeforeAddress { .. } | BackfillScopeValue::AfterAddress { .. } => {
+                std::option::Option::None
+            },
+        };
+    }
+}
+
+impl std::fmt::Debug for BackfillScope {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut debug = formatter.debug_struct("BackfillScope");
+        debug.field("kind", &self.kind());
+        match &self.value {
+            BackfillScopeValue::LatestAddress { address } => {
+                debug.field("address", address);
+            },
+            BackfillScopeValue::BeforeAddress { address, .. } | BackfillScopeValue::AfterAddress { address, .. } => {
+                debug.field("address", address).field("anchor", &"<redacted>");
+            },
+            BackfillScopeValue::ExplicitSignatures { signatures } => {
+                debug.field("signature_count", &signatures.len());
+            },
+        }
+        return debug.finish();
+    }
+}
+
+/// Opaque deterministic fingerprint of one semantic Backfill scope.
+#[derive(Clone, Copy, Eq, Hash, PartialEq)]
+pub struct BackfillScopeFingerprint([u8; 32]);
+
+impl BackfillScopeFingerprint {
+    /// Returns the exact deterministic fingerprint bytes.
+    #[must_use]
+    pub const fn as_bytes(&self) -> &[u8; 32] {
+        return &self.0;
+    }
+}
+
+impl std::fmt::Debug for BackfillScopeFingerprint {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        return formatter.write_str("BackfillScopeFingerprint(..)");
+    }
+}
+
+/// Fully explicit bounded request for one historical transaction Backfill Job.
+#[derive(Clone, Eq, PartialEq)]
+pub struct BackfillRequest {
+    job_id: ksp_job_api::JobId,
+    network: ksp_store_lib::RawNetworkId,
+    role: ksp_onchain_transport_lib::HttpRoleName,
+    commitment: BackfillCommitment,
+    scope: BackfillScope,
+    page_size: usize,
+    max_pages: usize,
+    max_candidates: usize,
+    hydration_concurrency: usize,
+    min_context_slot: std::option::Option<u64>,
+    scope_fingerprint: BackfillScopeFingerprint,
+}
+
+impl BackfillRequest {
+    /// Creates and validates one fully explicit bounded Backfill request.
+    #[allow(clippy::too_many_arguments)]
+    pub fn new(
+        job_id: ksp_job_api::JobId,
+        network: ksp_store_lib::RawNetworkId,
+        role: ksp_onchain_transport_lib::HttpRoleName,
+        commitment: BackfillCommitment,
+        scope: BackfillScope,
+        page_size: usize,
+        max_pages: usize,
+        max_candidates: usize,
+        hydration_concurrency: usize,
+        min_context_slot: std::option::Option<u64>,
+    ) -> ksp_core_lib::Result<Self> {
+        if page_size == 0 || page_size > crate::MAX_BACKFILL_PAGE_SIZE {
+            return std::result::Result::Err(request_error("page_size"));
+        }
+        if max_pages == 0 || max_pages > crate::MAX_BACKFILL_PAGES {
+            return std::result::Result::Err(request_error("max_pages"));
+        }
+        if max_candidates == 0 || max_candidates > crate::MAX_BACKFILL_CANDIDATES {
+            return std::result::Result::Err(request_error("max_candidates"));
+        }
+        if hydration_concurrency == 0 || hydration_concurrency > crate::MAX_BACKFILL_HYDRATION_CONCURRENCY {
+            return std::result::Result::Err(request_error("hydration_concurrency"));
+        }
+        if role.as_str().is_empty() || role.as_str().trim() != role.as_str() {
+            return std::result::Result::Err(request_error("role"));
+        }
+        if scope.kind() == BackfillScopeKind::ExplicitSignatures {
+            if min_context_slot.is_some() {
+                return std::result::Result::Err(request_error("min_context_slot"));
+            }
+            let signature_count = match scope.signatures() {
+                std::option::Option::Some(signatures) => signatures.len(),
+                std::option::Option::None => return std::result::Result::Err(request_error("scope.signatures")),
+            };
+            if signature_count > max_candidates {
+                return std::result::Result::Err(request_error("max_candidates"));
+            }
+        }
+        let scope_fingerprint = fingerprint_scope(&network, commitment, &scope, page_size, max_pages, max_candidates, min_context_slot);
+        return std::result::Result::Ok(Self {
+            job_id,
+            network,
+            role,
+            commitment,
+            scope,
+            page_size,
+            max_pages,
+            max_candidates,
+            hydration_concurrency,
+            min_context_slot,
+            scope_fingerprint,
+        });
+    }
+
+    /// Returns the caller-owned logical Job identity.
+    #[must_use]
+    pub const fn job_id(&self) -> &ksp_job_api::JobId {
+        return &self.job_id;
+    }
+
+    /// Returns the Store-scoped logical network identity for every candidate in this Job.
+    #[must_use]
+    pub const fn network(&self) -> &ksp_store_lib::RawNetworkId {
+        return &self.network;
+    }
+
+    /// Returns the logical HTTP role used only for Transport selection.
+    #[must_use]
+    pub const fn role(&self) -> &ksp_onchain_transport_lib::HttpRoleName {
+        return &self.role;
+    }
+
+    /// Returns the narrowed commitment used by discovery and hydration.
+    #[must_use]
+    pub const fn commitment(&self) -> BackfillCommitment {
+        return self.commitment;
+    }
+
+    /// Returns the validated discovery scope.
+    #[must_use]
+    pub const fn scope(&self) -> &BackfillScope {
+        return &self.scope;
+    }
+
+    /// Returns the per-request signature page size.
+    #[must_use]
+    pub const fn page_size(&self) -> usize {
+        return self.page_size;
+    }
+
+    /// Returns the maximum number of address pages admitted by this Job.
+    #[must_use]
+    pub const fn max_pages(&self) -> usize {
+        return self.max_pages;
+    }
+
+    /// Returns the maximum number of transaction candidates admitted by this Job.
+    #[must_use]
+    pub const fn max_candidates(&self) -> usize {
+        return self.max_candidates;
+    }
+
+    /// Returns the future hydration concurrency bound.
+    #[must_use]
+    pub const fn hydration_concurrency(&self) -> usize {
+        return self.hydration_concurrency;
+    }
+
+    /// Returns the optional Solana minimum context slot used by address discovery.
+    #[must_use]
+    pub const fn min_context_slot(&self) -> std::option::Option<u64> {
+        return self.min_context_slot;
+    }
+
+    /// Returns the deterministic semantic scope fingerprint.
+    ///
+    /// Transport role, provider, endpoint and protocol are deliberately excluded. They describe
+    /// acquisition provenance, not transaction or scope identity.
+    #[must_use]
+    pub const fn scope_fingerprint(&self) -> BackfillScopeFingerprint {
+        return self.scope_fingerprint;
+    }
+}
+
+impl std::fmt::Debug for BackfillRequest {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        return formatter
+            .debug_struct("BackfillRequest")
+            .field("job_id", &self.job_id)
+            .field("network", &self.network)
+            .field("role", &self.role)
+            .field("commitment", &self.commitment)
+            .field("scope", &self.scope)
+            .field("page_size", &self.page_size)
+            .field("max_pages", &self.max_pages)
+            .field("max_candidates", &self.max_candidates)
+            .field("hydration_concurrency", &self.hydration_concurrency)
+            .field("min_context_slot", &self.min_context_slot)
+            .field("scope_fingerprint", &self.scope_fingerprint)
+            .finish();
+    }
+}
+
+fn fingerprint_scope(
+    network: &ksp_store_lib::RawNetworkId,
+    commitment: BackfillCommitment,
+    scope: &BackfillScope,
+    page_size: usize,
+    max_pages: usize,
+    max_candidates: usize,
+    min_context_slot: std::option::Option<u64>,
+) -> BackfillScopeFingerprint {
+    let mut hasher = sha2::Sha256::new();
+    hasher.update(b"ksp.job.backfill.scope.v1\0");
+    hash_bytes(&mut hasher, network.as_str().as_bytes());
+    hash_bytes(&mut hasher, commitment.code().as_bytes());
+    hash_bytes(&mut hasher, scope.kind().code().as_bytes());
+    if let std::option::Option::Some(address) = scope.address() {
+        hash_bytes(&mut hasher, address.as_ref());
+    }
+    if let std::option::Option::Some(anchor) = scope.anchor() {
+        hash_bytes(&mut hasher, anchor.as_str().as_bytes());
+    }
+    if let std::option::Option::Some(signatures) = scope.signatures() {
+        for signature in signatures {
+            hash_bytes(&mut hasher, signature.as_str().as_bytes());
+        }
+    }
+    hash_u64(&mut hasher, page_size as u64);
+    hash_u64(&mut hasher, max_pages as u64);
+    hash_u64(&mut hasher, max_candidates as u64);
+    match min_context_slot {
+        std::option::Option::Some(slot) => {
+            hasher.update([1_u8]);
+            hash_u64(&mut hasher, slot);
+        },
+        std::option::Option::None => hasher.update([0_u8]),
+    }
+    let bytes: [u8; 32] = hasher.finalize().into();
+    return BackfillScopeFingerprint(bytes);
+}
+
+fn hash_bytes(hasher: &mut sha2::Sha256, value: &[u8]) {
+    hash_u64(hasher, value.len() as u64);
+    hasher.update(value);
+}
+
+fn hash_u64(hasher: &mut sha2::Sha256, value: u64) {
+    hasher.update(value.to_be_bytes());
+}
+
+fn request_error(field: &'static str) -> ksp_core_lib::Error {
+    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_REQUEST_INVALID, "invalid bounded Backfill request").with_context("field", field);
+}
+
+fn signature_error() -> ksp_core_lib::Error {
+    return ksp_core_lib::Error::new(crate::ERROR_CODE_BACKFILL_SIGNATURE_INVALID, "invalid bounded Backfill transaction signature")
+        .with_context("field", "signature");
+}
+
+fn valid_signature_text(value: &str) -> bool {
+    if value.len() < crate::MIN_BACKFILL_SIGNATURE_TEXT_BYTES || value.len() > crate::MAX_BACKFILL_SIGNATURE_TEXT_BYTES {
+        return false;
+    }
+    return value.bytes().all(|byte| {
+        return matches!(byte, b'1'..=b'9' | b'A'..=b'H' | b'J'..=b'N' | b'P'..=b'Z' | b'a'..=b'k' | b'm'..=b'z');
+    });
+}
+
+#[cfg(test)]
+#[path = "../unit_tests/request.rs"]
+mod tests;