dig-rpc-protocol 0.10.1

//! Request/response wire types for every DIG-node RPC method.
//!
//! Each type is `serde`-derived and models a method's params or result
//! field-for-field with the canonical implementation (the digstore `dig-node`
//! crate). Fields that appear only in one profile or only on the first window of
//! a paged stream are `Option` and doc-flagged.
//!
//! Hex-encoded identifiers (`store_id`, `root`, `retrieval_key`, `peer_id`) are
//! carried as `String` on the wire — lower-case 64-hex — because the interface
//! crate does no crypto and imposes no byte-array dependency. Callers validate
//! length/charset at their boundary.
//!
//! # Two content profiles, one chunk type
//!
//! [`ContentChunk`] models both the node profile (`dig.getContent` on the local
//! dig-node) and the network profile (`rpc.dig.net`). The network-profile-only
//! fields — [`total_length`](ContentChunk::total_length),
//! [`length`](ContentChunk::length), [`program_hash`](ContentChunk::program_hash),
//! [`offset`](ContentChunk::offset) — are `Option` so one type serves both
//! surfaces with no silent split.

use serde::{Deserialize, Serialize};

/// A lower-case 64-hex identifier on the wire (e.g. a `store_id`, `root`,
/// `retrieval_key`, or `peer_id`). A type alias for documentation; validation is
/// the boundary's job.
pub type HexId = String;

// ===========================================================================
// Shared value objects
// ===========================================================================

/// A peer's dialable network endpoint.
///
/// IPv6-first per the ecosystem networking rule: an address list orders
/// global-unicast IPv6 ahead of IPv4 fallback, and a wildcard bind
/// (`[::]`/`0.0.0.0`) is never advertised.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeerAddress {
    /// The host — an IPv6 or IPv4 literal (never a wildcard).
    pub host: String,
    /// The TCP port.
    pub port: u16,
    /// How the address was discovered: `direct`, `reflexive`, `mapped`, or
    /// `relay`.
    pub kind: String,
}

/// A content provider: a holder's stable `peer_id` plus its candidate addresses.
///
/// The address list is byte-compatible with [`dig.getPeers`](crate::method::Method::GetPeers)
/// and the DHT provider shape.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct Provider {
    /// The holder's stable `peer_id` = `SHA-256(TLS SPKI DER)`, 64-hex.
    pub peer_id: HexId,
    /// The holder's candidate addresses (IPv6-first).
    pub addresses: Vec<PeerAddress>,
}

/// The content item a redirect points at: `store_id` [+ `root` [+
/// `retrieval_key`]], each lower-case 64-hex — the exact item to re-request.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ContentRef {
    /// The store launcher id (always present).
    pub store_id: HexId,
    /// The generation root (present for capsule/resource granularity).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub root: Option<HexId>,
    /// The resource retrieval key (present for resource granularity).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub retrieval_key: Option<HexId>,
}

/// The `error.data.redirect` payload of a
/// [`ContentRedirect`](crate::error::ErrorCode::ContentRedirect) (`-32008`).
///
/// The node does not hold the content but located peers that do; the caller
/// re-requests against one of `providers`, echoing `redirect_depth` in its
/// params so the hop budget stays bounded (stop at `max_redirects`).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct RedirectInfo {
    /// The content the caller should re-request.
    pub content: ContentRef,
    /// The holders (peer_id + candidate addresses) to re-request against.
    pub providers: Vec<Provider>,
    /// The hop count the caller must echo on its re-request.
    pub redirect_depth: u64,
    /// The redirect budget — stop redirecting when `redirect_depth` reaches this.
    pub max_redirects: u64,
}

// ===========================================================================
// dig.getContent  (PUBLIC-READ, also peer-reachable)
// ===========================================================================

/// Params for [`dig.getContent`](crate::method::Method::GetContent) — a verified
/// resource-window read.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct GetContentParams {
    /// The CHIP-0035 singleton launcher id (64-hex).
    pub store_id: HexId,
    /// `SHA-256(urn)` — the only URN-derived value sent to a node (64-hex).
    pub retrieval_key: HexId,
    /// The generation root (64-hex). Empty / `"latest"` / absent ⇒ resolve the
    /// chain tip.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub root: Option<HexId>,
    /// The window start offset (default 0).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub offset: Option<u64>,
    /// Retrieval mode: `"speed"` (default) or `"privacy"` (onion — target).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub mode: Option<String>,
    /// The redirect budget already consumed (echoed from a `-32008` redirect).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub redirect_depth: Option<u64>,
}

/// One window of a resource's ciphertext — the chunk wire object.
///
/// Serves BOTH the node profile (`dig.getContent` on the local dig-node) and the
/// network profile (`rpc.dig.net`). Node-profile responses omit the
/// network-profile-only fields; the doc on each field says which profile
/// populates it.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ContentChunk {
    /// This window's bytes, base64. Both profiles.
    pub ciphertext: String,
    /// The resolved generation root (64-hex). Both profiles.
    pub root: HexId,
    /// Whether this window ends the resource. Both profiles.
    pub complete: bool,
    /// The next offset; present iff not complete. Both profiles.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub next_offset: Option<u64>,
    /// Whole-resource merkle proof, base64. First window only (`offset == 0`).
    /// Both profiles.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub inclusion_proof: Option<String>,
    /// Per-chunk ciphertext lengths of the full resource. First window only;
    /// empty ⇒ single chunk. Both profiles.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub chunk_lens: Option<Vec<u64>>,
    /// Where the window was served from: `"local"` (this device's cache) or
    /// `"remote"` (freshly fetched). **Node profile only** — additive tag the
    /// in-process node sets; absent on the network profile.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub source: Option<String>,
    /// The full resource ciphertext length (pre-windowing). **Network profile
    /// only.**
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub total_length: Option<u64>,
    /// This window's byte length. **Network profile only** (the node profile's
    /// length is implicit in `ciphertext`).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub length: Option<u64>,
    /// The window start offset (echoed). **Network profile only.**
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub offset: Option<u64>,
    /// `SHA-256(.dig bytes)` — the on-chain program identity (64-hex).
    /// **Network profile only.**
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub program_hash: Option<HexId>,
}

// ===========================================================================
// dig.getAnchoredRoot  (PUBLIC-READ, also peer-reachable)
// ===========================================================================

/// Params for [`dig.getAnchoredRoot`](crate::method::Method::GetAnchoredRoot).
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct GetAnchoredRootParams {
    /// The store launcher id (64-hex).
    pub store_id: HexId,
}

/// Result for [`dig.getAnchoredRoot`](crate::method::Method::GetAnchoredRoot) —
/// the store's current chain-anchored tip root.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AnchoredRoot {
    /// The store launcher id (echoed, 64-hex).
    pub store_id: HexId,
    /// The chain-anchored tip root (64-hex).
    pub root: HexId,
}

// ===========================================================================
// dig.getCollection / dig.listCollectionItems  (PUBLIC-READ, also peer)
// ===========================================================================

/// Params for [`dig.getCollection`](crate::method::Method::GetCollection).
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct GetCollectionParams {
    /// The NFT launcher ids to resolve. Capped at 10,000 (over-cap ⇒ `-32602`).
    pub launcher_ids: Vec<HexId>,
    /// The optional collection creator DID (64-hex).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub did: Option<HexId>,
}

/// Result for [`dig.getCollection`](crate::method::Method::GetCollection) —
/// collection-level facts computed from DIG's own coinset data.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct Collection {
    /// The resolved creator DID (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub did: Option<HexId>,
    /// The DID declared by the caller / metadata (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub declared_did: Option<HexId>,
    /// The number of launcher ids requested.
    pub item_count: u64,
    /// How many resolved to live NFTs.
    pub resolved_count: u64,
    /// The uniform royalty in basis points, if resolvable.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub royalty_basis_points: Option<u64>,
}

/// Params for
/// [`dig.listCollectionItems`](crate::method::Method::ListCollectionItems).
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ListCollectionItemsParams {
    /// The NFT launcher ids. Capped at 10,000 (over-cap ⇒ `-32602`).
    pub launcher_ids: Vec<HexId>,
    /// Page start (default 0).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub offset: Option<u64>,
    /// Page size (default 50, capped at 200).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub limit: Option<u64>,
}

/// CHIP-0007 NFT metadata for one collection item.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct NftMetadata {
    /// Edition ordinal, if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub edition_number: Option<u64>,
    /// Edition total, if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub edition_total: Option<u64>,
    /// Data URIs.
    #[serde(default)]
    pub data_uris: Vec<String>,
    /// `SHA-256` of the data (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub data_hash: Option<HexId>,
    /// Metadata URIs.
    #[serde(default)]
    pub metadata_uris: Vec<String>,
    /// `SHA-256` of the metadata document (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub metadata_hash: Option<HexId>,
    /// License URIs.
    #[serde(default)]
    pub license_uris: Vec<String>,
    /// `SHA-256` of the license (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub license_hash: Option<HexId>,
}

/// One resolved collection item — its current on-chain owner, royalty, and
/// CHIP-0007 metadata.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CollectionItem {
    /// The NFT launcher id (64-hex).
    pub launcher_id: HexId,
    /// The current coin id (64-hex).
    pub coin_id: HexId,
    /// The current owner DID (64-hex), if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub owner_did: Option<HexId>,
    /// The royalty puzzle hash (64-hex).
    pub royalty_puzzle_hash: HexId,
    /// The royalty in basis points.
    pub royalty_basis_points: u64,
    /// The current owner puzzle hash (64-hex).
    pub owner_puzzle_hash: HexId,
    /// The CHIP-0007 metadata, if resolvable.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub metadata: Option<NftMetadata>,
}

/// Result for
/// [`dig.listCollectionItems`](crate::method::Method::ListCollectionItems) — a
/// page of resolved items.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CollectionItemsPage {
    /// This page's items.
    pub items: Vec<CollectionItem>,
    /// The page start (echoed).
    pub offset: u64,
    /// The page size (echoed).
    pub limit: u64,
    /// The total item count across the whole (capped) launcher set.
    pub total: u64,
    /// The next page's offset, or `null` when exhausted.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub next_offset: Option<u64>,
}

// ===========================================================================
// dig.getNetworkInfo  (PEER)
// ===========================================================================

/// The node's relay reservation posture.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct RelayStatus {
    /// The relay endpoint URL (e.g. `wss://relay.dig.net:9450`).
    pub url: String,
    /// Whether a relay reservation is currently held.
    pub reserved: bool,
}

/// Result for [`dig.getNetworkInfo`](crate::method::Method::GetNetworkInfo) —
/// this node's own peer-network posture.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct NetworkInfo {
    /// This node's stable `peer_id` = `SHA-256(TLS SPKI DER)` (64-hex), or
    /// `null` when no identity is configured.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub peer_id: Option<HexId>,
    /// The DIG network id (e.g. `DIG_MAINNET`).
    pub network_id: String,
    /// The first advertised (dialable) candidate address, `host:port`.
    pub listen_addr: String,
    /// The STUN-discovered reflexive address, if known.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub reflexive_addr: Option<String>,
    /// All advertised candidate addresses (IPv6-first).
    pub candidate_addresses: Vec<String>,
    /// Reachability posture: `"direct"` or `"relayed"`.
    pub reachability: String,
    /// The relay reservation posture.
    pub relay: RelayStatus,
}

// ===========================================================================
// dig.getPeers  (PEER)
// ===========================================================================

/// Result for [`dig.getPeers`](crate::method::Method::GetPeers) — the peers this
/// node currently knows (peer exchange over RPC).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeersList {
    /// The known peers (peer_id + candidate addresses).
    pub peers: Vec<Provider>,
}

// ===========================================================================
// dig.announce  (PEER)
// ===========================================================================

/// Params for [`dig.announce`](crate::method::Method::Announce).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AnnounceParams {
    /// The announcing peer's `peer_id` (64-hex).
    pub peer_id: HexId,
    /// The announcing peer's candidate addresses.
    pub addresses: Vec<PeerAddress>,
}

/// Result for [`dig.announce`](crate::method::Method::Announce).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AnnounceAck {
    /// Whether the announcement was accepted.
    pub accepted: bool,
    /// How many peers this node now knows.
    pub known_peers: u64,
}

// ===========================================================================
// dig.getAvailability  (PEER)
// ===========================================================================

/// One availability query item. Granularity is inferred from which fields are
/// present: `store_id` only ⇒ which roots are held; `+root` ⇒ a capsule; `+root
/// +retrieval_key` ⇒ a resource.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AvailabilityQuery {
    /// The store launcher id (64-hex, required).
    pub store_id: HexId,
    /// The generation root (64-hex), for capsule/resource granularity.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub root: Option<HexId>,
    /// The resource retrieval key (64-hex), for resource granularity.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub retrieval_key: Option<HexId>,
}

/// Params for [`dig.getAvailability`](crate::method::Method::GetAvailability).
///
/// # Construction
///
/// Like [`FetchRangeParams`], this type is `#[non_exhaustive]`: build it with
/// [`new`](Self::new) plus the `with_*` setters rather than a struct literal, so a
/// future additive field is a PATCH for every consumer instead of a semver cascade.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct GetAvailabilityParams {
    /// The items to check. Capped at 512 per batch (past-cap items are dropped).
    pub items: Vec<AvailabilityQuery>,
    /// The hop budget already consumed by this ask. Absent means zero — read it
    /// through [`hops_consumed`](Self::hops_consumed), never directly.
    ///
    /// # What it means for an availability ask
    ///
    /// An availability answer is not only *this* node's holdings: on a miss it may
    /// name the holders it located, in
    /// [`AvailabilityAnswer::providers`](AvailabilityAnswer::providers) — the same
    /// enrichment a [`RedirectInfo`] carries. A responder that cannot answer from
    /// what it holds MAY ask its own peers, so one caller's question can walk
    /// several hops, and each hop is a node spending someone else's bandwidth.
    /// This field is what bounds that walk.
    ///
    /// It is the SAME budget, counted the SAME way, as
    /// [`RedirectInfo::redirect_depth`] and as the `redirect_depth` that
    /// [`GetContentParams`] and [`FetchRangeParams`] already echo: the number of
    /// hops ALREADY CONSUMED when this ask arrives, counting UP from zero — never a
    /// remaining allowance counting down. A responder that asks onward sends
    /// `hops_consumed() + 1` (saturating at the type maximum), and MUST NOT ask
    /// onward when that would reach the budget it advertises as
    /// [`RedirectInfo::max_redirects`].
    ///
    /// Absent reads as a fresh, unhopped ask, so a client written before this field
    /// existed is served unchanged.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub redirect_depth: Option<u64>,
    /// The wall-clock TIME this ask may still spend, in milliseconds. Absent means
    /// unbudgeted — read it through [`budget_ms`](Self::budget_ms), never directly.
    ///
    /// # Why this is its OWN field and not the hop budget
    ///
    /// [`redirect_depth`](Self::redirect_depth) counts hops UP from zero toward a
    /// ceiling; this counts milliseconds DOWN toward zero. The two move in opposite
    /// directions along different axes, so one integer cannot carry both, and folding
    /// them together would make "one more hop" and "more time" the same request.
    ///
    /// # The contract a relaying responder MUST honour
    ///
    /// A responder that asks its own peers onward MUST pass a value it has decremented
    /// by the time it has itself already spent, and it MUST NOT grant a child less time
    /// than the work it asks that child to do. Concretely: a parent that asks `n`
    /// children SEQUENTIALLY must divide the remaining budget between them, and a
    /// parent with less time left than one round trip needs MUST answer
    /// [`ContentMissInconclusive`](crate::error::ErrorCode::ContentMissInconclusive)
    /// rather than ask onward and then time out.
    ///
    /// This exists because the alternative is measurable: a FIXED per-ask bound with
    /// sequential asks and a fan-out greater than one guarantees the second hop times
    /// out, and a responder that reads that timeout as a miss reports a CONFIDENT
    /// not-found for content it never looked for.
    ///
    /// Absent reads as unbudgeted, so a client written before this field existed is
    /// served exactly as it was.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub budget_ms: Option<u64>,
    /// An opaque identity for this ask, for cross-path dedup. Absent means the caller
    /// opted out of dedup — read it through [`ask_id`](Self::ask_id).
    ///
    /// # What it is for
    ///
    /// A recursive ask walks a graph, not a tree. Two disjoint paths can arrive at the
    /// same responder, and without a shared identity that responder cannot tell a
    /// re-walk from a fresh question — so a diamond in the peer graph does not
    /// terminate. A responder that has already seen an `ask_id` MUST answer from what
    /// it already knows instead of asking onward again.
    ///
    /// # What it is NOT
    ///
    /// It is **not** the JSON-RPC `id`. That field correlates one request with one
    /// response on one connection; it is chosen per-connection, is commonly a small
    /// constant, and says nothing about whether two arrivals are the same ask. An
    /// implementation that reused the JSON-RPC `id` for dedup would either collide
    /// every unrelated ask together or dedup nothing at all.
    ///
    /// # Requirements
    ///
    /// 32 lowercase hex characters: **16 unpredictable random bytes**, freshly drawn
    /// by the ORIGINATOR and copied verbatim by every relaying hop. It MUST be
    /// unpredictable, because a value an attacker can guess lets that attacker
    /// pre-poison a responder dedup memo and suppress an ask that has not happened
    /// yet. A responder MUST NOT derive anything from its value beyond EQUALITY — it
    /// carries no structure, no origin, no timestamp and no ordering.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub ask_id: Option<String>,
}

impl GetAvailabilityParams {
    /// An availability batch for `items`, asked at hop zero.
    pub fn new(items: Vec<AvailabilityQuery>) -> Self {
        GetAvailabilityParams {
            items,
            redirect_depth: None,
            budget_ms: None,
            ask_id: None,
        }
    }

    /// Echo the hop budget already consumed — from a `-32008` redirect, or from the
    /// ask this one is being made on behalf of. See
    /// [`redirect_depth`](Self::redirect_depth).
    pub fn with_redirect_depth(mut self, redirect_depth: u64) -> Self {
        self.redirect_depth = Some(redirect_depth);
        self
    }

    /// The hops already consumed by this ask.
    ///
    /// The single home for the "absent means zero" rule. A responder that reached for
    /// `redirect_depth.is_some()` instead would read every pre-0.8 client's ask as
    /// budget-free and forward it without bound — the amplification the budget exists
    /// to stop.
    pub fn hops_consumed(&self) -> u64 {
        self.redirect_depth.unwrap_or(0)
    }

    /// Set the remaining time budget for this ask. See [`budget_ms`](Self::budget_ms).
    pub fn with_budget_ms(mut self, budget_ms: u64) -> Self {
        self.budget_ms = Some(budget_ms);
        self
    }

    /// The time this ask may still spend, or `None` when the caller sent no budget.
    ///
    /// Deliberately NOT collapsed to a number, unlike
    /// [`hops_consumed`](Self::hops_consumed): there is no safe scalar default. Zero
    /// would refuse every older caller ask outright, and any positive default would
    /// silently impose one node idea of patience on another node question. A responder
    /// that receives `None` applies its OWN policy and passes on what it granted.
    pub fn budget_ms(&self) -> Option<u64> {
        self.budget_ms
    }

    /// Set the cross-path dedup identity. See [`ask_id`](Self::ask_id).
    pub fn with_ask_id(mut self, ask_id: impl Into<String>) -> Self {
        self.ask_id = Some(ask_id.into());
        self
    }

    /// The dedup identity, or `None` when the caller opted out of dedup.
    pub fn ask_id(&self) -> Option<&str> {
        self.ask_id.as_deref()
    }
}

/// One availability answer. Only the fields relevant to the query's granularity
/// are populated.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AvailabilityAnswer {
    /// Whether this node holds the queried item.
    pub available: bool,
    /// The roots held (store-granularity queries only).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub roots: Option<Vec<HexId>>,
    /// The full resource ciphertext length (resource-granularity only).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub total_length: Option<u64>,
    /// The chunk count (resource-granularity only).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub chunk_count: Option<u64>,
    /// Whether the whole item is held (root/resource-granularity only).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub complete: Option<bool>,
    /// Providers that hold the item — present on a miss when holders were
    /// located (enriched answer).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub providers: Option<Vec<Provider>>,
    /// Whether this responder actually ESTABLISHED that nobody holds the item.
    ///
    /// Only meaningful beside `available: false`; on a hit the item is held and there
    /// is nothing to establish.
    ///
    /// # Absent is a THIRD state, not `false`
    ///
    /// - `Some(true)` — the responder looked, reached everything it meant to reach,
    ///   and asserts absence. A client MAY stop searching.
    /// - `Some(false)` — the responder looked and could NOT establish absence: a hop
    ///   timed out, was unreachable, or refused uninformatively. A client MUST keep
    ///   looking. This is the in-band form of
    ///   [`ContentMissInconclusive`](crate::error::ErrorCode::ContentMissInconclusive),
    ///   for a batch where only SOME items were inconclusive and the call itself
    ///   therefore succeeded.
    /// - `None` — the responder predates this field and makes NO claim either way.
    ///   It is NOT `Some(false)`: `Some(false)` is a responder telling you its search
    ///   was incomplete, while `None` is a responder that cannot describe its search at
    ///   all. Conflating them lets an older server every miss be read as a positive
    ///   report of incompleteness; conflating it the other way (`unwrap_or(true)`)
    ///   turns an unknown into an assertion of absence. Read it through
    ///   [`absence_established_or_unknown`](AvailabilityAnswer::absence_established_or_unknown),
    ///   which keeps the three states distinct.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub absence_established: Option<bool>,
}

impl AvailabilityAnswer {
    /// Whether absence was established, as a THREE-state answer: `Some(true)`
    /// asserted, `Some(false)` explicitly not established, `None` unknown because the
    /// responder predates the field.
    ///
    /// A pass-through, and that is the point — it is the named home for the rule that
    /// there is no safe collapse to `bool`. A client that wants to stop searching MUST
    /// require `Some(true)`.
    pub fn absence_established_or_unknown(&self) -> Option<bool> {
        self.absence_established
    }
}

/// Result for [`dig.getAvailability`](crate::method::Method::GetAvailability) —
/// one answer per query item, in order.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct AvailabilityBatch {
    /// The per-item answers (index-aligned to the query items served).
    pub items: Vec<AvailabilityAnswer>,
}

// ===========================================================================
// dig.listInventory  (PEER)
// ===========================================================================

/// Params for [`dig.listInventory`](crate::method::Method::ListInventory).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ListInventoryParams {
    /// The store to list roots for (64-hex). Absent ⇒ list all stores served.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub store_id: Option<HexId>,
    /// The maximum number of entries to return.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub limit: Option<u64>,
}

/// Result for [`dig.listInventory`](crate::method::Method::ListInventory).
///
/// With a `store_id` the node returns the roots it holds for that store; without
/// one it returns the stores it serves. `#[serde(untagged)]` keeps the wire flat
/// (`{"roots": …}` or `{"stores": …}`).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(untagged)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub enum Inventory {
    /// The roots held for a specific store.
    ForStore {
        /// The store launcher id (echoed, 64-hex).
        store_id: HexId,
        /// The roots this node holds for the store.
        roots: Vec<HexId>,
    },
    /// The stores this node serves (no `store_id` given).
    AllStores {
        /// The store launcher ids served.
        stores: Vec<HexId>,
    },
}

// ===========================================================================
// dig.fetchRange  (PEER)
// ===========================================================================

/// Params for [`dig.fetchRange`](crate::method::Method::FetchRange) — a single
/// range frame of a resource this node holds.
///
/// # Construction
///
/// Like [`RangeFrame`], this type is `#[non_exhaustive]`: build it with
/// [`resource`](Self::resource) plus the `with_*` setters rather than a struct
/// literal, so a future additive field is a PATCH for every consumer instead of a
/// semver cascade.
///
/// # Cross-repo contract
///
/// [`skip_layout`](Self::skip_layout) is byte-identical to
/// `dig_nat::mux::RangeRequest::skip_layout`, pinned in
/// `tests/nat_wire_mirror.rs`. The two enclosing types deliberately differ in every
/// other respect — dig-nat's `RangeRequest` is a length-prefixed stream preamble,
/// this is a JSON-RPC params object with a `redirect_depth` dig-nat has no notion
/// of — so the byte-identical contract here is the FIELD, not the object.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct FetchRangeParams {
    /// The store launcher id (64-hex, required).
    pub store_id: HexId,
    /// The generation root (64-hex, required for a resource fetch).
    pub root: HexId,
    /// `SHA-256(urn)` (64-hex, required for a resource fetch).
    pub retrieval_key: HexId,
    /// The range start (default 0).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub offset: Option<u64>,
    /// The range length in bytes (> 0; clamped to the window cap).
    pub length: u64,
    /// Whole-capsule mode (default false). Capsule range fetch is not yet
    /// served; a `true` here yields `-32004`.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub capsule: Option<bool>,
    /// The redirect budget already consumed (echoed from a `-32008` redirect).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub redirect_depth: Option<u64>,
    /// Suppress the resource-scaling layout metadata (`chunk_lens` +
    /// `inclusion_proof`) on this stream's frames, because the client already holds
    /// the commitment for this `root`.
    ///
    /// A client that has already read the layout once — a resumed download, a second
    /// range of the same resource, a parallel fetch from another holder — does not
    /// need it again, and re-sending it costs a whole paged prologue PER STREAM: a
    /// 1,048,576-chunk layout is roughly 7.3 MB, which a 64-way parallel plan would
    /// otherwise pay 64 times over. Suppressing it is the difference between a
    /// bounded and an unbounded cost on the read path.
    ///
    /// Absent or `false` preserves the pre-0.6.0 behaviour, so an older holder that
    /// ignores this field is never broken by it — it simply sends metadata the client
    /// discards. Read the rule through
    /// [`suppresses_layout`](Self::suppresses_layout) rather than re-deriving it.
    ///
    /// The fixed-size identity fields ([`root`](RangeFrame::root),
    /// [`total_length`](RangeFrame::total_length),
    /// [`chunk_count`](RangeFrame::chunk_count),
    /// [`chunk_index`](RangeFrame::chunk_index)) are NOT suppressed: they are what
    /// detects a wrong-generation holder on arrival, and a client that stopped
    /// receiving them would lose that check on exactly the streams it fetches most.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub skip_layout: Option<bool>,
}

impl FetchRangeParams {
    /// A range request for one content resource: `length` bytes of
    /// `retrieval_key`'s ciphertext at the generation `root`.
    pub fn resource(
        store_id: impl Into<HexId>,
        root: impl Into<HexId>,
        retrieval_key: impl Into<HexId>,
        length: u64,
    ) -> Self {
        FetchRangeParams {
            store_id: store_id.into(),
            root: root.into(),
            retrieval_key: retrieval_key.into(),
            offset: None,
            length,
            capsule: None,
            redirect_depth: None,
            skip_layout: None,
        }
    }

    /// Start the range at `offset` rather than at 0.
    pub fn with_offset(mut self, offset: u64) -> Self {
        self.offset = Some(offset);
        self
    }

    /// Request whole-capsule mode. Capsule range fetch is not yet served — a `true`
    /// here yields
    /// [`ResourceUnavailable`](crate::error::ErrorCode::ResourceUnavailable).
    pub fn with_capsule(mut self, capsule: bool) -> Self {
        self.capsule = Some(capsule);
        self
    }

    /// Echo the redirect budget already consumed, from a `-32008` redirect.
    pub fn with_redirect_depth(mut self, redirect_depth: u64) -> Self {
        self.redirect_depth = Some(redirect_depth);
        self
    }

    /// Ask the holder to omit the resource-scaling layout metadata, because this
    /// client already holds the commitment for this `root`. See
    /// [`skip_layout`](Self::skip_layout).
    pub fn with_skip_layout(mut self, skip_layout: bool) -> Self {
        self.skip_layout = Some(skip_layout);
        self
    }

    /// Whether this request suppresses the resource-scaling layout metadata.
    ///
    /// The single home for the "absent or `false` means SEND the layout" rule. A
    /// serve path that reached for `skip_layout.is_some()` instead would suppress the
    /// layout for a client that had explicitly asked for it — unrecoverable for that
    /// client, since the layout is a decrypt input it cannot obtain any other way on
    /// that stream.
    pub fn suppresses_layout(&self) -> bool {
        self.skip_layout.unwrap_or(false)
    }
}

/// One range frame of a resource: a byte window, plus the per-resource
/// verification metadata that makes the window independently checkable.
///
/// The metadata splits in two by whether it scales with the resource, and the
/// split decides which frames carry it:
///
/// - **The identity set — [`root`](Self::root),
///   [`total_length`](Self::total_length), [`chunk_count`](Self::chunk_count),
///   plus [`chunk_index`](Self::chunk_index) when the window begins on a chunk
///   boundary — rides EVERY frame.** It is fixed-size, so carrying it everywhere
///   costs a bounded number of bytes, and it is what lets a client fetching in
///   parallel from many holders reject a wrong-generation or wrong-layout source
///   the moment a frame arrives, rather than after paying for the whole resource
///   in bandwidth.
/// - **The resource-scaling set — [`chunk_lens`](Self::chunk_lens) and
///   [`inclusion_proof`](Self::inclusion_proof) — rides the first frame, or a
///   paged prologue, once per range stream.** Repeating it per frame would cost
///   proportionally to the resource against a frame budget with no slack; a layout
///   too large to state on one frame is paged instead, each page stamped with the
///   [`chunk_lens_offset`](Self::chunk_lens_offset) it begins at.
///
/// The window is exactly the span the caller requested — never widened.
///
/// # Construction
///
/// This type is [`#[non_exhaustive]`](https://doc.rust-lang.org/reference/attributes/type_system.html):
/// build it with [`data`](Self::data) and the `with_*` setters rather than a struct
/// literal. That is deliberate — the wire form grows as the protocol does, and
/// routing construction through named setters means a future additive field is a
/// PATCH release for every consumer instead of another semver cascade. It also
/// makes the two frame shapes different call chains rather than one call with a
/// pile of `None`s, so a continuation frame cannot accidentally claim a layout it
/// is not stating.
///
/// # Cross-repo contract
///
/// The wire form is **byte-identical** to `dig_nat::mux::RangeFrame`, the
/// streaming implementation of this frame (`SYSTEM.md` → "Canonical DIG-node RPC
/// interface"). Field names, encodings, and the population rule above are pinned
/// against dig-nat's actual output in `tests/nat_wire_mirror.rs`; a change to any
/// of them lands in both crates in the same unit of work or not at all.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
#[non_exhaustive]
pub struct RangeFrame {
    /// The window start offset (echoed).
    pub offset: u64,
    /// This window's byte length.
    pub length: u64,
    /// This window's ciphertext, base64.
    pub bytes: String,
    /// Whether this frame ends the resource.
    pub complete: bool,
    /// The full resource ciphertext length. Part of the fixed-size **identity
    /// set**, so it rides EVERY frame.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub total_length: Option<u64>,
    /// Per-chunk ciphertext lengths of the full resource, in order — the layout a
    /// reader needs before it can decrypt (per-chunk AEAD needs the WHOLE array,
    /// and a reader rejects an array whose sum differs from
    /// [`total_length`](Self::total_length)).
    ///
    /// Resource-scaling, so it rides the first frame or a **paged prologue**, once
    /// per range stream — never repeated on continuation frames. When paged, this
    /// is one page of the array and
    /// [`chunk_lens_offset`](Self::chunk_lens_offset) states the entry it begins
    /// at.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub chunk_lens: Option<Vec<u64>>,
    /// This frame's first chunk index — the pre-existing alias of
    /// [`first_chunk_index`](Self::first_chunk_index), carrying the same value, and
    /// the name dig-nat emits.
    ///
    /// Part of the **identity set**: it rides every frame whose window begins on a
    /// chunk boundary, and is OMITTED (rather than guessed) on a mid-chunk window.
    /// Being fixed-size, it is settable on its own — see
    /// [`with_chunk_index`](Self::with_chunk_index) — precisely so a continuation
    /// frame can state it without dragging along the once-per-stream
    /// [`inclusion_proof`](Self::inclusion_proof).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub chunk_index: Option<u64>,
    /// Whole-resource merkle proof against [`root`](Self::root), base64, relayed
    /// verbatim.
    ///
    /// Resource-scaling, so it rides the first frame or the paged prologue, once
    /// per range stream. A holder MUST NOT repeat it per frame: it is bounded at
    /// 4,096 base64 bytes, which against the frame budget leaves no slack for the
    /// payload the frame exists to carry.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub inclusion_proof: Option<String>,
    /// The chain-anchored root (64-hex) this frame's resource verified against.
    /// Part of the fixed-size **identity set**, so it rides EVERY frame.
    ///
    /// NOT A TRUST ANCHOR BY ITSELF. The client resolves the resource's root from
    /// the URN (chain-anchored) and PINS it before fetching; a peer-declared value
    /// never replaces that pinned root. What this field provides is a
    /// generation-CONSISTENCY check: a frame declaring a root other than the pinned
    /// one is REJECTED and attributed to the offending peer (NC-9 fail-closed). So
    /// a declared root can only ever cause rejection — it can never move the pinned
    /// root, and never makes an unverified frame acceptable.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub root: Option<HexId>,
    /// **RESERVED — not currently derivable; a server MUST NOT emit it.**
    ///
    /// Per-chunk merkle inclusion proofs for the chunks a frame covers. No such
    /// proof exists in the current store format: the generation root's merkle
    /// leaves are per-RESOURCE (a leaf is the SHA-256 of a resource's WHOLE
    /// ciphertext), so a single chunk has no leaf to prove. A client MUST NOT
    /// require this field, and per-range verification instead uses the
    /// whole-resource [`inclusion_proof`](Self::inclusion_proof) together with the
    /// per-frame [`root`](Self::root)/[`chunk_lens`](Self::chunk_lens) metadata.
    ///
    /// Making it derivable requires a per-resource chunk-level commitment in the
    /// store format first (tracked as `dig_ecosystem#1601`). The field is kept in
    /// the wire type, unused, so populating it later is additive (§5.1); each entry
    /// would be an opaque base64 proof blob, since this pure level-00 wire type
    /// MUST NOT depend on the merkle primitive.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub range_proof: Option<Vec<String>>,
    /// The chunk index of the first chunk in this frame (0-based, into the
    /// resource's chunk sequence described by [`chunk_lens`](Self::chunk_lens)).
    ///
    /// Present only when the frame's window begins EXACTLY on a chunk boundary; a
    /// mid-chunk window omits it rather than assert an index the caller's own
    /// alignment check would contradict. The served window is exactly the requested
    /// span — a server MUST NOT widen a range to a chunk boundary — so a frame is
    /// chunk-aligned only when the caller asked for an aligned span.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub first_chunk_index: Option<u64>,
    /// The resource's TOTAL chunk count — how many entries the fully reassembled
    /// [`chunk_lens`](Self::chunk_lens) array has.
    ///
    /// Fixed-size, so it belongs to the **identity set** and rides EVERY frame.
    /// Together with [`root`](Self::root) and
    /// [`total_length`](Self::total_length) it is what lets a reader detect a
    /// wrong-generation or wrong-layout holder on the first frame it receives. It is
    /// also how a reader sizes the array it is paging in, and therefore how it knows
    /// a **paged prologue** is complete: the prologue ends when the reader holds
    /// `chunk_count` entries, which no single page can tell it.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub chunk_count: Option<u64>,
    /// The index into the resource's [`chunk_lens`](Self::chunk_lens) array at which
    /// THIS frame's page begins — how a **paged prologue** is located and
    /// reassembled.
    ///
    /// A resource whose layout exceeds the per-frame entry cap cannot state it on
    /// one frame, so the sender pages it: successive frames each carry up to that
    /// many entries, stamped with the offset they start at. A reader places each page
    /// at its offset and holds the whole array once it has
    /// [`chunk_count`](Self::chunk_count) entries.
    ///
    /// Absent means "this frame's `chunk_lens`, if any, begins at entry 0" — the
    /// single-frame layout, which is the shape every pre-0.6.0 producer emits. So an
    /// older frame decodes with exactly its original meaning (§5.1).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub chunk_lens_offset: Option<u64>,
}

impl RangeFrame {
    /// A **data frame**: `length` bytes of base64 ciphertext at `offset`, carrying
    /// no metadata — the bare shape every continuation frame starts from.
    ///
    /// `length` is stated rather than derived because [`bytes`](Self::bytes) is
    /// already base64 on this type, and recovering the raw window length from it
    /// would need a base64 codec this pure level-00 wire crate deliberately does not
    /// depend on. A serve path passes the length it served.
    pub fn data(offset: u64, length: u64, bytes: impl Into<String>) -> Self {
        RangeFrame {
            offset,
            length,
            bytes: bytes.into(),
            complete: false,
            total_length: None,
            chunk_lens: None,
            chunk_index: None,
            inclusion_proof: None,
            root: None,
            range_proof: None,
            first_chunk_index: None,
            chunk_count: None,
            chunk_lens_offset: None,
        }
    }

    /// Mark this as the final frame of the range.
    pub fn with_complete(mut self, complete: bool) -> Self {
        self.complete = complete;
        self
    }

    /// The fixed-size **identity set** every frame of a range carries: the
    /// generation `root` (64-hex) the range is served from, the resource's
    /// ciphertext `total_length`, and its `chunk_count`.
    ///
    /// These three are what let a reader reject a wrong-generation or wrong-layout
    /// holder the moment a frame arrives — which the resource-scaling metadata never
    /// could, since it arrives once. Call this on every frame.
    pub fn with_identity(
        mut self,
        root: impl Into<HexId>,
        total_length: u64,
        chunk_count: u64,
    ) -> Self {
        self.root = Some(root.into());
        self.total_length = Some(total_length);
        self.chunk_count = Some(chunk_count);
        self
    }

    /// State [`chunk_index`](Self::chunk_index) — the chunk this frame's window
    /// begins on — for a chunk-aligned window.
    ///
    /// Separate from [`with_inclusion_proof`](Self::with_inclusion_proof) on purpose:
    /// the index is fixed-size identity metadata that rides every aligned frame,
    /// while the proof is once-per-stream, so binding them together would force a
    /// producer to either repeat a proof it MUST NOT repeat or bypass this API. Omit
    /// the call entirely for a mid-chunk window.
    pub fn with_chunk_index(mut self, chunk_index: u64) -> Self {
        self.chunk_index = Some(chunk_index);
        self
    }

    /// Additionally state [`first_chunk_index`](Self::first_chunk_index), this
    /// crate's v0.4.0 alias of [`chunk_index`](Self::chunk_index).
    ///
    /// Both names carry the same value. dig-nat emits only `chunk_index`, so
    /// [`with_chunk_index`](Self::with_chunk_index) alone is the interoperable
    /// choice; a producer serving readers that expect the newer name states both.
    pub fn with_first_chunk_index(mut self, first_chunk_index: u64) -> Self {
        self.first_chunk_index = Some(first_chunk_index);
        self
    }

    /// One page of the resource's `chunk_lens` array, beginning at entry
    /// `chunk_lens_offset`.
    ///
    /// Call it once with offset `0` for a layout that fits a single frame, or once
    /// per page of a **paged prologue**. A page is only ever useful as part of a
    /// complete set: `chunk_lens` is a decrypt input, and a reader needs all
    /// [`chunk_count`](Self::chunk_count) entries before it can decrypt anything.
    pub fn with_chunk_lens_page(mut self, chunk_lens_offset: u64, chunk_lens: Vec<u64>) -> Self {
        self.chunk_lens_offset = Some(chunk_lens_offset);
        self.chunk_lens = Some(chunk_lens);
        self
    }

    /// The whole-resource merkle inclusion proof against
    /// [`root`](Self::root) (base64, relayed verbatim).
    ///
    /// Resource-scaling: state it on the first frame or the prologue, once per range
    /// stream, never per frame.
    pub fn with_inclusion_proof(mut self, inclusion_proof: impl Into<String>) -> Self {
        self.inclusion_proof = Some(inclusion_proof.into());
        self
    }

    /// State the **RESERVED** [`range_proof`](Self::range_proof) field.
    ///
    /// A server MUST NOT emit it — no per-chunk proof is derivable from the current
    /// store format (see the field's own documentation). The setter exists so the
    /// shape stays constructible for the conformance vectors that pin it, and so no
    /// field of this `#[non_exhaustive]` type is unreachable; it is not a serve-path
    /// call.
    pub fn with_range_proof(mut self, range_proof: Vec<String>) -> Self {
        self.range_proof = Some(range_proof);
        self
    }
}

// ===========================================================================
// dig.getModuleInfo / dig.fetchModuleRange  (PEER — whole-module pull, #1576)
// ===========================================================================

/// Params for [`dig.getModuleInfo`](crate::method::Method::GetModuleInfo) — the
/// handshake a peer reads before range-pulling a whole `.dig` module for
/// `(store, root)`.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct GetModuleInfoParams {
    /// The store launcher id (64-hex, required).
    pub store_id: HexId,
    /// The generation root whose `.dig` module is being pulled (64-hex, required).
    pub root: HexId,
}

/// Result for [`dig.getModuleInfo`](crate::method::Method::GetModuleInfo) — the
/// transfer descriptor of a whole `.dig` module.
///
/// The whole-module blob is content-addressed + immutable (the `.dig` container
/// is byte-identical by construction). [`module_hash`](Self::module_hash) is the
/// content id of the assembled blob; a puller verifies each pulled range against
/// [`chunk_hashes`](Self::chunk_hashes) (per-peer attribution on a multi-source
/// pull) and the fully-assembled blob against `module_hash`, THEN verifies the
/// assembled module against its chain-anchored root before admitting + resharing
/// (NC-9 verified-content-not-safe-content).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ModuleInfo {
    /// The total byte length of the whole `.dig` module blob.
    pub total_size: u64,
    /// The content id of the fully-assembled module blob (64-hex `SHA-256` of the
    /// module bytes). The puller checks the assembled blob against this.
    pub module_hash: HexId,
    /// Per-chunk content hashes (64-hex each) in ascending chunk order, covering
    /// the blob in [`total_size`](Self::total_size)-spanning fixed-size chunks
    /// (the trailing chunk may be short). A puller checks each pulled
    /// [`RangeFrame`] against the covering entries for per-source attribution on a
    /// multi-source pull (a tampered range fails closed before assembly).
    pub chunk_hashes: Vec<HexId>,
    /// Per-chunk byte lengths (in the same order as [`chunk_hashes`](Self::chunk_hashes)).
    /// MUST have the same length as `chunk_hashes` and MUST sum to `total_size`.
    /// A puller uses these to map a fetched byte range to the covering chunk hash(es).
    pub chunk_lens: Vec<u64>,
}

/// Params for [`dig.fetchModuleRange`](crate::method::Method::FetchModuleRange) —
/// a single range frame of the whole `.dig` module blob for `(store, root)`.
///
/// The response reuses [`RangeFrame`]: [`bytes`](RangeFrame::bytes) carries the
/// window of the module blob (base64), [`total_length`](RangeFrame::total_length)
/// echoes the whole-module size on the first frame, and
/// [`complete`](RangeFrame::complete) ends the stream.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct FetchModuleRangeParams {
    /// The store launcher id (64-hex, required).
    pub store_id: HexId,
    /// The generation root whose `.dig` module is being pulled (64-hex, required).
    pub root: HexId,
    /// The range start into the module blob (default 0).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub offset: Option<u64>,
    /// The range length in bytes (> 0; clamped to the window cap).
    pub length: u64,
}

// ===========================================================================
// dig.stage  (CONTROL — loopback / in-process only)
// ===========================================================================

/// Params for [`dig.stage`](crate::method::Method::Stage) — compile a local
/// folder into a capsule `.dig` module in-process.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct StageParams {
    /// The absolute path to the folder to compile.
    pub dir: String,
    /// The target store launcher id (64-hex). Absent ⇒ an ephemeral,
    /// content-derived id (a preview).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub store_id: Option<HexId>,
    /// The store salt (64-hex). Present ⇒ a private store.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub salt: Option<HexId>,
    /// Optional DIGHub-style manifest metadata to embed.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub metadata: Option<serde_json::Value>,
}

/// Result for [`dig.stage`](crate::method::Method::Stage) — the compiled capsule.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct StageResult {
    /// The canonical capsule identity, `storeId:rootHash`.
    pub capsule: String,
    /// The store launcher id (64-hex).
    pub store_id: HexId,
    /// The compiled generation root (64-hex).
    pub root: HexId,
    /// The filesystem path to the compiled `.dig` module.
    pub module_path: String,
    /// The module size in bytes.
    pub size: u64,
    /// The `chia://storeId:rootHash/` content address.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub content_address: Option<String>,
    /// The relative paths compiled into the capsule.
    #[serde(default)]
    pub files: Vec<String>,
    /// Whether this is an ephemeral preview (not advancing a real store).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub ephemeral: Option<bool>,
}

// ===========================================================================
// cache.*  (CONTROL — loopback / in-process only)
// ===========================================================================

/// Result for [`cache.getConfig`](crate::method::Method::CacheGetConfig).
///
/// The canonical field name for the cache path is `cache_dir` everywhere (the
/// shell's historical `dir` is unified onto this name).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CacheConfig {
    /// The on-disk cache size cap in bytes (floored at 64 MiB).
    pub cap_bytes: u64,
    /// The bytes currently used.
    pub used_bytes: u64,
    /// The effective resolved cache directory.
    pub cache_dir: String,
    /// Whether that directory is the canonical shared location (vs a
    /// process-private fallback).
    pub shared: bool,
}

/// Params for [`cache.setCapBytes`](crate::method::Method::CacheSetCapBytes).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct SetCapBytesParams {
    /// The requested cap in bytes (floored at 64 MiB by the node).
    pub cap_bytes: u64,
}

/// Result for [`cache.setCapBytes`](crate::method::Method::CacheSetCapBytes).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct SetCapBytesResult {
    /// The effective cap after flooring.
    pub cap_bytes: u64,
}

/// One durable cached-module entry.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CachedCapsule {
    /// The canonical capsule identity, `storeId:rootHash`.
    pub capsule: String,
    /// The store launcher id (64-hex).
    pub store_id: HexId,
    /// The generation root (64-hex).
    pub root: HexId,
    /// The module size in bytes.
    pub size_bytes: u64,
    /// When the module was last used (unix ms).
    pub last_used_unix_ms: u64,
}

/// Result for [`cache.listCached`](crate::method::Method::CacheListCached).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CachedList {
    /// The cached capsules.
    pub cached: Vec<CachedCapsule>,
}

/// Params for a capsule-keyed cache op
/// ([`cache.removeCached`](crate::method::Method::CacheRemoveCached),
/// [`cache.fetchAndCache`](crate::method::Method::CacheFetchAndCache)).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CapsuleKey {
    /// The store launcher id (64-hex).
    pub store_id: HexId,
    /// The generation root (64-hex).
    pub root: HexId,
}

/// Result for [`cache.removeCached`](crate::method::Method::CacheRemoveCached).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct RemoveCachedResult {
    /// Whether an entry was removed.
    pub removed: bool,
}

/// Result for [`cache.fetchAndCache`](crate::method::Method::CacheFetchAndCache).
///
/// A failed fetch is reported in-band (`status = "failed"` + `message`) so the
/// caller can show it without treating it as a transport error.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct FetchAndCacheResult {
    /// `"cached"`, `"already_cached"`, or `"failed"`.
    pub status: String,
    /// The fetched module size in bytes (on success).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub size_bytes: Option<u64>,
    /// The served generation root (64-hex, on success).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub served_root: Option<HexId>,
    /// The failure message (on `status = "failed"`).
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub message: Option<String>,
}

// ===========================================================================
// control.peerStatus  (CONTROL — loopback / in-process only)
// ===========================================================================

/// Result for [`control.peerStatus`](crate::method::Method::ControlPeerStatus) —
/// a snapshot of the node's L7 peer network. Always safe to call; reports
/// `running: false` on the FFI path.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeerStatusSnapshot {
    /// Whether a peer network is currently active.
    pub running: bool,
    /// This node's `peer_id` (64-hex), if a peer network is running.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub peer_id: Option<HexId>,
    /// The DIG network id.
    pub network_id: String,
    /// The relay reservation posture.
    pub relay: RelayStatus,
    /// The number of currently connected peers.
    pub connected_peers: u64,
    /// The last peer-network error, if any.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub last_error: Option<String>,
}

// ===========================================================================
// cache.stats  (CONTROL — loopback / in-process only)
// ===========================================================================

/// The decoded-content cache hit/miss counters carried in
/// [`CacheStats`](CacheStats::content_cache).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct ContentCacheCounters {
    /// Session decoded-content cache hits.
    pub hits: u64,
    /// Session decoded-content cache misses.
    pub misses: u64,
}

/// Result for [`cache.stats`](crate::method::Method::CacheStats) — cache
/// telemetry beside [`cache.getConfig`](crate::method::Method::CacheGetConfig):
/// the reserved cap + live usage, the cached-capsule count + total on-disk
/// bytes, and the session eviction + content-cache counters.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct CacheStats {
    /// The on-disk cache size cap in bytes.
    pub cap_bytes: u64,
    /// The bytes currently used on disk.
    pub used_bytes: u64,
    /// The number of durable cached capsules.
    pub entry_count: u64,
    /// The total on-disk bytes across the cached capsules.
    pub total_bytes: u64,
    /// Capsules evicted this session.
    pub evicted_count: u64,
    /// Bytes evicted this session.
    pub evicted_bytes: u64,
    /// The decoded-content cache hit/miss counters.
    pub content_cache: ContentCacheCounters,
}

// ===========================================================================
// control.subscribe / control.unsubscribe / control.listSubscriptions
// (CONTROL — loopback / in-process only)
// ===========================================================================

/// Params for [`control.subscribe`](crate::method::Method::ControlSubscribe) and
/// [`control.unsubscribe`](crate::method::Method::ControlUnsubscribe).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct SubscribeParams {
    /// The store launcher id to (un)subscribe (64-hex).
    pub store_id: HexId,
}

/// Result for [`control.subscribe`](crate::method::Method::ControlSubscribe).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct SubscribeResult {
    /// Always `true` — the store is subscribed after this call.
    pub subscribed: bool,
    /// Whether this call ADDED the subscription (`false` ⇒ already subscribed).
    pub added: bool,
    /// The canonical persisted store id (trimmed + lower-cased, 64-hex).
    pub store_id: HexId,
}

/// Result for [`control.unsubscribe`](crate::method::Method::ControlUnsubscribe).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct UnsubscribeResult {
    /// Always `false` — the store is not subscribed after this call.
    pub subscribed: bool,
    /// Whether this call REMOVED a subscription (`false` ⇒ was not subscribed).
    pub removed: bool,
    /// The canonical persisted store id (trimmed + lower-cased, 64-hex).
    pub store_id: HexId,
}

/// Result for
/// [`control.listSubscriptions`](crate::method::Method::ControlListSubscriptions).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct SubscriptionsList {
    /// The persisted subscribed store ids (64-hex each).
    pub subscriptions: Vec<HexId>,
    /// The subscription count (`subscriptions.len()`).
    pub count: u64,
}

// ===========================================================================
// control.peers.connect / control.peers.disconnect
// (CONTROL — loopback / in-process only)
// ===========================================================================

/// Params for [`control.peers.connect`](crate::method::Method::ControlPeersConnect)
/// and [`control.peers.disconnect`](crate::method::Method::ControlPeersDisconnect).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeerConnectParams {
    /// The peer to dial/drop — a dialable address, or a known peer's `peer_id`
    /// (64-hex) to resolve an already-connected peer.
    pub peer: String,
}

/// Result for
/// [`control.peers.connect`](crate::method::Method::ControlPeersConnect).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeerConnectResult {
    /// Always `true` on success — the peer is a counted, connected pool member.
    pub connected: bool,
    /// The connected peer's stable `peer_id` (64-hex).
    pub peer_id: HexId,
}

/// Result for
/// [`control.peers.disconnect`](crate::method::Method::ControlPeersDisconnect).
///
/// Idempotent: disconnecting a peer that is not connected succeeds as a no-op.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct PeerDisconnectResult {
    /// Always `true` — the peer is not in the pool after this call.
    pub disconnected: bool,
    /// The dropped peer's `peer_id` (trimmed + lower-cased, 64-hex).
    pub peer_id: HexId,
}

// ===========================================================================
// dig.health / dig.methods / rpc.discover  (discovery)
// ===========================================================================

/// Result for [`dig.health`](crate::method::Method::Health) — liveness + a
/// capability summary.
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct Health {
    /// Liveness — `"ok"` when the node can serve.
    pub status: String,
    /// The node's software version.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub version: Option<String>,
    /// The DIG network id the node serves.
    #[serde(skip_serializing_if = "Option::is_none", default)]
    pub network_id: Option<String>,
    /// The method names this node implements (its profile).
    #[serde(default)]
    pub methods: Vec<String>,
}

/// Result for [`dig.methods`](crate::method::Method::Methods) — the method names
/// this node implements (agent self-describe).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
#[cfg_attr(feature = "schema-export", derive(schemars::JsonSchema))]
pub struct Methods {
    /// The implemented method names.
    pub methods: Vec<String>,
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    /// **Proves:** `ContentChunk` round-trips a node-profile window (no
    /// network-profile fields) without inventing keys.
    /// **Catches:** a missing `skip_serializing_if` that would leak `null`
    /// network-profile fields onto the node profile.
    #[test]
    fn content_chunk_node_profile_is_lean() {
        let c = ContentChunk {
            ciphertext: "AAA=".into(),
            root: "ab".repeat(32),
            complete: false,
            next_offset: Some(3_145_728),
            inclusion_proof: Some("cHJvb2Y=".into()),
            chunk_lens: Some(vec![10, 20]),
            source: Some("local".into()),
            total_length: None,
            length: None,
            offset: None,
            program_hash: None,
        };
        let v = serde_json::to_value(&c).unwrap();
        assert_eq!(v["source"], "local");
        assert!(
            v.get("total_length").is_none(),
            "node profile must omit total_length"
        );
        assert!(v.get("program_hash").is_none());
        assert_eq!(serde_json::from_value::<ContentChunk>(v).unwrap(), c);
    }

    /// **Proves:** the network-profile fields serialize when present.
    #[test]
    fn content_chunk_network_profile_carries_extras() {
        let c = ContentChunk {
            ciphertext: "AAA=".into(),
            root: "cd".repeat(32),
            complete: true,
            next_offset: None,
            inclusion_proof: None,
            chunk_lens: None,
            source: None,
            total_length: Some(100),
            length: Some(100),
            offset: Some(0),
            program_hash: Some("ef".repeat(32)),
        };
        let v = serde_json::to_value(&c).unwrap();
        assert_eq!(v["total_length"], 100);
        assert_eq!(v["length"], 100);
        assert!(v.get("source").is_none());
    }

    /// **Proves:** the untagged `Inventory` picks `ForStore` vs `AllStores` by
    /// shape.
    /// **Catches:** a lost `#[serde(untagged)]` that would tag the variant.
    #[test]
    fn inventory_untagged_by_shape() {
        let for_store = Inventory::ForStore {
            store_id: "ab".repeat(32),
            roots: vec!["cd".repeat(32)],
        };
        let s = serde_json::to_string(&for_store).unwrap();
        assert!(s.contains("\"roots\""));
        assert!(!s.contains("ForStore"));
        assert_eq!(serde_json::from_str::<Inventory>(&s).unwrap(), for_store);

        let all = Inventory::AllStores {
            stores: vec!["ef".repeat(32)],
        };
        let s = serde_json::to_string(&all).unwrap();
        assert!(s.contains("\"stores\""));
        assert_eq!(serde_json::from_str::<Inventory>(&s).unwrap(), all);
    }

    /// **Proves:** `RedirectInfo` serializes the full redirect payload the
    /// `-32008` envelope carries.
    #[test]
    fn redirect_info_shape() {
        let r = RedirectInfo {
            content: ContentRef {
                store_id: "ab".repeat(32),
                root: Some("cd".repeat(32)),
                retrieval_key: Some("ef".repeat(32)),
            },
            providers: vec![Provider {
                peer_id: "12".repeat(32),
                addresses: vec![PeerAddress {
                    host: "::1".into(),
                    port: 9444,
                    kind: "direct".into(),
                }],
            }],
            redirect_depth: 1,
            max_redirects: 4,
        };
        let v = serde_json::to_value(&r).unwrap();
        assert_eq!(v["redirect_depth"], 1);
        assert_eq!(v["max_redirects"], 4);
        assert_eq!(v["providers"][0]["addresses"][0]["host"], "::1");
        assert_eq!(serde_json::from_value::<RedirectInfo>(v).unwrap(), r);
    }

    /// **Proves:** `cache.stats` models the live dig-node result field-for-field
    /// (the nested `content_cache{hits,misses}` object included).
    /// **Catches:** a drift from the node's `cache.stats` wire shape (#1075).
    #[test]
    fn cache_stats_wire_shape() {
        let s = CacheStats {
            cap_bytes: 1 << 30,
            used_bytes: 2048,
            entry_count: 3,
            total_bytes: 2048,
            evicted_count: 1,
            evicted_bytes: 512,
            content_cache: ContentCacheCounters { hits: 7, misses: 2 },
        };
        let v = serde_json::to_value(s).unwrap();
        assert_eq!(v["cap_bytes"], 1 << 30);
        assert_eq!(v["entry_count"], 3);
        assert_eq!(v["content_cache"]["hits"], 7);
        assert_eq!(v["content_cache"]["misses"], 2);
        assert_eq!(serde_json::from_value::<CacheStats>(v).unwrap(), s);
    }

    /// **Proves:** the subscription-management results carry the exact
    /// `{subscribed, added|removed, store_id}` / `{subscriptions, count}` shapes
    /// the live node returns.
    #[test]
    fn subscription_result_shapes() {
        let sub = SubscribeResult {
            subscribed: true,
            added: true,
            store_id: "ab".repeat(32),
        };
        let v = serde_json::to_value(&sub).unwrap();
        assert_eq!(v["subscribed"], true);
        assert_eq!(v["added"], true);
        assert_eq!(serde_json::from_value::<SubscribeResult>(v).unwrap(), sub);

        let unsub = UnsubscribeResult {
            subscribed: false,
            removed: true,
            store_id: "cd".repeat(32),
        };
        let v = serde_json::to_value(&unsub).unwrap();
        assert_eq!(v["subscribed"], false);
        assert_eq!(v["removed"], true);
        assert_eq!(
            serde_json::from_value::<UnsubscribeResult>(v).unwrap(),
            unsub
        );

        let list = SubscriptionsList {
            subscriptions: vec!["ef".repeat(32)],
            count: 1,
        };
        let v = serde_json::to_value(&list).unwrap();
        assert_eq!(v["count"], 1);
        assert_eq!(
            serde_json::from_value::<SubscriptionsList>(v).unwrap(),
            list
        );
    }

    /// **Proves:** `ModuleInfo` carries `chunk_lens` covering every chunk, and
    /// round-trips with unknown future fields.
    /// **Catches:** a missing `chunk_lens` field that would leave a puller unable
    /// to map a fetched byte range to its covering chunk hash.
    /// **Invariants enforced by docs:** `chunk_lens` must have the same length as
    /// `chunk_hashes` and must sum to `total_size`.
    #[test]
    fn module_info_chunk_lens_shape() {
        let info = ModuleInfo {
            total_size: 1024,
            module_hash: "ab".repeat(32),
            chunk_hashes: vec!["cd".repeat(32), "ef".repeat(32)],
            chunk_lens: vec![512, 512],
        };
        let v = serde_json::to_value(&info).unwrap();
        assert_eq!(v["total_size"], 1024);
        assert_eq!(v["chunk_hashes"].as_array().unwrap().len(), 2);
        assert_eq!(v["chunk_lens"].as_array().unwrap().len(), 2);
        assert_eq!(v["chunk_lens"][0], 512);
        assert_eq!(v["chunk_lens"][1], 512);
        assert_eq!(serde_json::from_value::<ModuleInfo>(v).unwrap(), info);
    }

    /// **Proves:** `ModuleInfo` deserialization REJECTS missing `chunk_lens` field.
    /// This is a REQUIRED field (not optional) — omitting it from the wire is a
    /// protocol violation and must fail-closed.
    #[test]
    fn module_info_rejects_missing_chunk_lens() {
        let json_str = r#"{"total_size": 2048, "module_hash": "1122334455667788990011223344556677889900112233445566778899001122", "chunk_hashes": []}"#;
        let result: Result<ModuleInfo, _> = serde_json::from_str(json_str);
        assert!(
            result.is_err(),
            "ModuleInfo must reject JSON missing the required chunk_lens field"
        );
        let err = result.unwrap_err();
        assert!(
            err.to_string().contains("chunk_lens"),
            "error message should mention chunk_lens: {}",
            err
        );
    }

    /// **Proves:** the peer connect/disconnect params + results round-trip and
    /// match the node's `{connected|disconnected, peer_id}` shapes.
    #[test]
    fn peer_connect_disconnect_shapes() {
        let p = PeerConnectParams {
            peer: "12".repeat(32),
        };
        let v = serde_json::to_value(&p).unwrap();
        assert_eq!(serde_json::from_value::<PeerConnectParams>(v).unwrap(), p);

        let c = PeerConnectResult {
            connected: true,
            peer_id: "12".repeat(32),
        };
        let v = serde_json::to_value(&c).unwrap();
        assert_eq!(v["connected"], true);
        assert_eq!(serde_json::from_value::<PeerConnectResult>(v).unwrap(), c);

        let d = PeerDisconnectResult {
            disconnected: true,
            peer_id: "34".repeat(32),
        };
        let v = serde_json::to_value(&d).unwrap();
        assert_eq!(v["disconnected"], true);
        assert_eq!(
            serde_json::from_value::<PeerDisconnectResult>(v).unwrap(),
            d
        );
    }

    /// **Proves:** `cache.getConfig` uses the canonical `cache_dir` field name.
    /// **Catches:** a regression to the shell's historical `dir` name.
    #[test]
    fn cache_config_field_name_is_cache_dir() {
        let c = CacheConfig {
            cap_bytes: 1 << 30,
            used_bytes: 0,
            cache_dir: "/var/cache/dig".into(),
            shared: true,
        };
        let v = serde_json::to_value(&c).unwrap();
        assert!(v.get("cache_dir").is_some());
        assert!(v.get("dir").is_none(), "must not use the legacy `dir` name");
    }

    /// **Proves:** an OLDER client's `dig.getAvailability` params — written
    /// before the hop budget existed — still deserialize, and read as a fresh,
    /// unhopped ask.
    /// **Catches:** a `redirect_depth` declared as a required `u64`, which
    /// rejects exactly these params with `missing field redirect_depth` and would
    /// make every pre-0.8 caller's ask a parse error at the peer boundary.
    /// **Guarded by:** the field's `Option` TYPE. `serde`'s derive already reads a
    /// missing `Option` field as `None`, so the `#[serde(default)]` beside it is
    /// parity with the sibling params types rather than the live guard — removing
    /// it alone leaves this test green (mutant-tested). Do not cite the attribute
    /// as the thing that keeps older clients working.
    #[test]
    fn get_availability_params_accepts_an_older_clients_params() {
        let older = json!({
            "items": [ { "store_id": "ab".repeat(32) } ]
        });
        let p: GetAvailabilityParams = serde_json::from_value(older).unwrap();
        assert_eq!(p.items.len(), 1);
        assert_eq!(p.redirect_depth, None, "an absent budget stays absent");
        assert_eq!(p.hops_consumed(), 0, "absent means zero hops consumed");
    }

    /// **Proves:** a hop-zero ask serializes to exactly the pre-0.8 bytes — the
    /// `redirect_depth` key is absent, not `null`.
    /// **Catches:** a bare `#[serde(default)]` without `skip_serializing_if`,
    /// which would add `"redirect_depth": null` to every existing caller's
    /// frame and change the wire for callers that never opted in.
    #[test]
    fn get_availability_params_omits_an_absent_hop_budget() {
        let p = GetAvailabilityParams::new(vec![AvailabilityQuery {
            store_id: "ab".repeat(32),
            root: None,
            retrieval_key: None,
        }]);
        let v = serde_json::to_value(&p).unwrap();
        let keys: Vec<&String> = v.as_object().unwrap().keys().collect();
        assert_eq!(keys, vec!["items"], "hop-zero params carry only `items`");
    }

    /// **Proves:** a hopped ask round-trips its budget under the `redirect_depth`
    /// key, and reads back through `hops_consumed`.
    #[test]
    fn get_availability_params_round_trips_the_hop_budget() {
        let p = GetAvailabilityParams::new(vec![AvailabilityQuery {
            store_id: "cd".repeat(32),
            root: Some("ef".repeat(32)),
            retrieval_key: None,
        }])
        .with_redirect_depth(2);
        let v = serde_json::to_value(&p).unwrap();
        assert_eq!(v["redirect_depth"], 2);
        assert_eq!(p.hops_consumed(), 2);
        assert_eq!(
            serde_json::from_value::<GetAvailabilityParams>(v).unwrap(),
            p
        );
    }

    /// **Proves:** an older client params object — written before ANY of the
    /// recursive-ask fields existed — still deserializes, and every new field reads
    /// as its documented absent value.
    /// **Catches:** any of the three declared as required, which would turn every
    /// pre-0.9 caller ask into `missing field` at the peer boundary.
    #[test]
    fn get_availability_params_accepts_a_client_older_than_the_recursive_ask() {
        let older = json!({ "items": [ { "store_id": "ab".repeat(32) } ] });
        let p: GetAvailabilityParams = serde_json::from_value(older).unwrap();

        assert_eq!(p.budget_ms(), None, "absent budget_ms means unbudgeted");
        assert_eq!(p.ask_id(), None, "absent ask_id means dedup opted out");
        assert_eq!(p.hops_consumed(), 0);
    }

    /// **Proves:** a params object carrying no recursive-ask fields serializes to
    /// exactly the pre-0.9 bytes — the three new keys are ABSENT, not `null`.
    /// **Catches:** a bare `#[serde(default)]` without `skip_serializing_if`, which
    /// would add `"budget_ms": null` and `"ask_id": null` to the frame of every
    /// caller that never opted in.
    #[test]
    fn get_availability_params_omits_absent_recursive_ask_fields() {
        let p = GetAvailabilityParams::new(vec![AvailabilityQuery {
            store_id: "ab".repeat(32),
            root: None,
            retrieval_key: None,
        }]);
        let v = serde_json::to_value(&p).unwrap();
        let keys: Vec<&String> = v.as_object().unwrap().keys().collect();
        assert_eq!(keys, vec!["items"], "a plain ask carries only `items`");
    }

    /// **Proves:** the time budget and the hop budget are two INDEPENDENT fields
    /// under two distinct keys, each round-tripping its own value.
    /// **Catches:** the shape defect this addition exists to prevent — folding the
    /// time budget into `redirect_depth`. The fixture sets them to DIFFERENT values
    /// (2 hops, 9000 ms) precisely so a single backing integer cannot satisfy both
    /// assertions; equal values would pass under either shape.
    #[test]
    fn the_time_budget_is_a_separate_field_from_the_hop_budget() {
        let p = GetAvailabilityParams::new(vec![AvailabilityQuery {
            store_id: "cd".repeat(32),
            root: None,
            retrieval_key: None,
        }])
        .with_redirect_depth(2)
        .with_budget_ms(9_000);

        let v = serde_json::to_value(&p).unwrap();
        assert_eq!(v["redirect_depth"], 2, "hops counted UP from zero");
        assert_eq!(v["budget_ms"], 9_000, "milliseconds counted DOWN to zero");
        assert_eq!(p.hops_consumed(), 2);
        assert_eq!(p.budget_ms(), Some(9_000));
        assert_eq!(
            serde_json::from_value::<GetAvailabilityParams>(v).unwrap(),
            p
        );
    }

    /// **Proves:** a zero time budget survives the wire as `Some(0)` and is NOT
    /// erased into `None`.
    /// **Catches:** a `skip_serializing_if` written over the VALUE rather than the
    /// Option (`is_zero`-style), which would make "you have no time left, do not ask
    /// onward" indistinguishable from "unbudgeted, use your own policy" — exactly
    /// inverting the field on the one hop where it matters most.
    #[test]
    fn a_zero_time_budget_is_not_the_same_as_an_absent_one() {
        let exhausted = GetAvailabilityParams::new(vec![]).with_budget_ms(0);
        let v = serde_json::to_value(&exhausted).unwrap();

        assert_eq!(v["budget_ms"], 0, "an exhausted budget stays on the wire");
        assert_eq!(
            serde_json::from_value::<GetAvailabilityParams>(v)
                .unwrap()
                .budget_ms(),
            Some(0)
        );
        assert_eq!(
            GetAvailabilityParams::new(vec![]).budget_ms(),
            None,
            "unbudgeted is a different state from budget zero"
        );
    }

    /// **Proves:** `ask_id` round-trips verbatim under its own key, and is NOT the
    /// JSON-RPC `id`.
    /// **Catches:** an implementation that reuses the envelope correlator for dedup.
    /// The fixture puts a hardcoded `"id": 1` — the exact value dig-node was sending
    /// — beside a real 16-byte ask id in one envelope, so a reader that took the
    /// correlator would see `1` and disagree with both assertions.
    #[test]
    fn the_ask_id_is_not_the_jsonrpc_correlator() {
        const ASK_ID: &str = "3f9c1a04b7e25d68f0a1c3b5d7e9f012";
        assert_eq!(ASK_ID.len(), 32, "16 random bytes as lowercase hex");

        let envelope = json!({
            "jsonrpc": "2.0",
            "id": 1,
            "method": "dig.getAvailability",
            "params": {
                "items": [ { "store_id": "ab".repeat(32) } ],
                "ask_id": ASK_ID,
            }
        });

        let p: GetAvailabilityParams = serde_json::from_value(envelope["params"].clone()).unwrap();
        assert_eq!(p.ask_id(), Some(ASK_ID));
        assert_ne!(
            p.ask_id(),
            Some("1"),
            "the dedup identity must not be read from the envelope `id`"
        );
        assert_eq!(envelope["id"], 1, "the correlator is untouched beside it");
    }

    /// **Proves:** `absence_established` distinguishes THREE states on the wire —
    /// asserted, explicitly-not-established, and unknown-because-older-server — and
    /// that the unknown state serializes as an ABSENT key rather than `false`.
    /// **Catches:** the collapse this field exists to prevent. The fixture carries
    /// all three answers in ONE batch, so a `bool` with `#[serde(default)]` (which
    /// would read the old server answer as `false`) makes the second and third
    /// answers compare EQUAL and the test fails; a fixture with only one answer
    /// could not see that.
    #[test]
    fn absence_established_keeps_absent_distinct_from_false() {
        let asserted = AvailabilityAnswer {
            available: false,
            absence_established: Some(true),
            ..Default::default()
        };
        let inconclusive = AvailabilityAnswer {
            available: false,
            absence_established: Some(false),
            ..Default::default()
        };
        let older_server = AvailabilityAnswer {
            available: false,
            ..Default::default()
        };

        assert_ne!(
            inconclusive, older_server,
            "an explicit `false` is a claim; an absent field is not"
        );
        assert_eq!(asserted.absence_established_or_unknown(), Some(true));
        assert_eq!(inconclusive.absence_established_or_unknown(), Some(false));
        assert_eq!(
            older_server.absence_established_or_unknown(),
            None,
            "an older server makes no claim either way"
        );

        let batch = serde_json::to_value(AvailabilityBatch {
            items: vec![asserted, inconclusive, older_server],
        })
        .unwrap();
        assert_eq!(batch["items"][0]["absence_established"], true);
        assert_eq!(batch["items"][1]["absence_established"], false);
        assert!(
            batch["items"][2].get("absence_established").is_none(),
            "the unknown state is an absent key, never `false` and never `null`"
        );
    }

    /// **Proves:** an OLDER client can still read a NEWER answer — the added field
    /// does not break the shipped shape (§5.1).
    #[test]
    fn an_answer_carrying_the_new_field_still_parses_as_the_shipped_shape() {
        let newer = json!({
            "items": [ { "available": false, "absence_established": true } ]
        });
        let b: AvailabilityBatch = serde_json::from_value(newer).unwrap();
        assert_eq!(b.items.len(), 1);
        assert!(!b.items[0].available);
        assert_eq!(b.items[0].absence_established_or_unknown(), Some(true));
    }

    /// **Proves:** the hop budget an availability ask carries is the SAME field,
    /// with the same key, type and value, that a `-32008` redirect hands back and
    /// that `dig.getContent` / `dig.fetchRange` already echo — one field, one
    /// interpretation, counted UP toward `max_redirects`.
    /// **Catches:** a second reading of the budget in this crate (a remaining
    /// allowance counting DOWN, a differently-named key, a differently-typed
    /// value) — the byte-drift the shipped redirect contract exists to prevent.
    #[test]
    fn availability_hop_budget_mirrors_the_redirect_budget() {
        let handed_back = RedirectInfo {
            content: ContentRef {
                store_id: "ab".repeat(32),
                root: None,
                retrieval_key: None,
            },
            providers: vec![],
            redirect_depth: 3,
            max_redirects: 4,
        };
        let echoed = handed_back.redirect_depth;

        let availability = serde_json::to_value(
            GetAvailabilityParams::new(vec![AvailabilityQuery {
                store_id: "ab".repeat(32),
                root: None,
                retrieval_key: None,
            }])
            .with_redirect_depth(echoed),
        )
        .unwrap();
        let content = serde_json::to_value(GetContentParams {
            store_id: "ab".repeat(32),
            retrieval_key: "cd".repeat(32),
            root: None,
            offset: None,
            mode: None,
            redirect_depth: Some(echoed),
        })
        .unwrap();
        let range = serde_json::to_value(
            FetchRangeParams::resource("ab".repeat(32), "cd".repeat(32), "ef".repeat(32), 1)
                .with_redirect_depth(echoed),
        )
        .unwrap();

        for (method, params) in [
            ("dig.getAvailability", &availability),
            ("dig.getContent", &content),
            ("dig.fetchRange", &range),
        ] {
            assert_eq!(
                params["redirect_depth"], 3,
                "{method} must carry the echoed depth under `redirect_depth`"
            );
        }
        assert!(
            handed_back.redirect_depth < handed_back.max_redirects,
            "the budget counts UP toward `max_redirects`"
        );
    }

    /// **Proves:** a NEWER client's params — carrying a field this build does not
    /// know — still deserialize, so a hop-bearing ask is never refused outright by
    /// an older responder that simply ignores the budget.
    /// **Catches:** a `#[serde(deny_unknown_fields)]` added to the params type,
    /// which would turn every forward-compatible extension into a hard parse
    /// failure at the peer boundary.
    #[test]
    fn get_availability_params_tolerates_an_unknown_field() {
        let newer = json!({
            "items": [ { "store_id": "ab".repeat(32) } ],
            "redirect_depth": 1,
            "a_field_this_build_does_not_know": true
        });
        let p: GetAvailabilityParams = serde_json::from_value(newer).unwrap();
        assert_eq!(p.hops_consumed(), 1);
    }
}