boatramp_server/

function_api.rs

//! The function management API (FA-1/FA-2): list function summaries and
//! deploy, version, alias, roll back, and remove function definitions. This is
//! the always-on control surface (no wasm engine required); the runtime that
//! invokes functions lives in `function_runtime`. Pulls the serve-pipeline
//! scope in via `use super::*`.

use super::*;

use boatramp_core::function::FunctionSummary;

/// `?site=` filter for the functions view.
#[derive(serde::Deserialize)]
pub(super) struct FunctionQuery {
    site: Option<String>,
}

/// `GET /api/functions[?site=…]` — the derived, **read-only** site-scoped function
/// view (FA-1): desugar each site's active manifest into functions + triggers and
/// resolve component paths to their blob-hash version ids. A pure projection of the
/// manifests — the serve path is untouched, so a site's handlers are unchanged.
/// `system·read`.
pub(super) async fn list_functions(
    State(deploy): State<DeployStore>,
    Extension(project): axum::extract::Extension<ProjectContext>,
    axum::extract::Query(query): axum::extract::Query<FunctionQuery>,
) -> Response {
    use boatramp_core::function;
    let sites = match &query.site {
        Some(s) => vec![s.clone()],
        None => match deploy.all_sites(project.as_ref()).await {
            Ok(s) => s,
            Err(err) => return deploy_error_response(err),
        },
    };
    let mut out: Vec<FunctionSummary> = Vec::new();
    for site in sites {
        let manifest = match deploy.current_manifest(project.as_ref(), &site).await {
            Ok(Some(m)) => m,
            Ok(None) => continue,
            Err(err) => return deploy_error_response(err),
        };
        let (specs, triggers) = function::desugar(&manifest.config);
        for f in function::materialize(&specs, &site, &manifest.files, 0) {
            let trigs = triggers
                .iter()
                .filter(|t| t.target.as_ref().map(|r| r.name.as_str()) == Some(f.name.as_str()))
                .map(std::string::ToString::to_string)
                .collect();
            out.push(FunctionSummary {
                name: format!("{site}/{}", f.name),
                owner: format!("site:{site}"),
                runtime: f.config.runtime.as_str().to_string(),
                version: f.active,
                triggers: trigs,
            });
        }
    }
    // Top-level (independently-stored) functions — FA-2. A `?site=` filter is
    // site-scoped only, so it excludes these.
    if query.site.is_none() {
        match deploy.list_stored_functions(project.as_ref()).await {
            Ok(stored) => {
                for f in stored {
                    out.push(FunctionSummary {
                        name: f.name.clone(),
                        owner: f.owner.to_string(),
                        runtime: f.config.runtime.as_str().to_string(),
                        version: f.active,
                        // A top-level function has a stable invoke URL (FA-3).
                        triggers: vec![format!("invoke {}", f.name)],
                    });
                }
            }
            Err(err) => return deploy_error_response(err),
        }
    }
    Json(out).into_response()
}

/// Body of `PUT /api/functions/:name` — deploy a version of a top-level function.
#[derive(serde::Deserialize)]
pub(super) struct FunctionUpsert {
    /// The component blob hash (uploaded first via `PUT /api/blobs/<hash>`).
    pub(super) component: String,
    /// Binding/capability config.
    #[serde(default)]
    pub(super) config: boatramp_core::function::FunctionConfig,
    /// Version lifecycle (defaults to `deploy-pinned`; top-level functions choose
    /// `independent`).
    #[serde(default)]
    pub(super) lifecycle: boatramp_core::function::Lifecycle,
}

/// Query for `PUT /api/functions/:name`.
#[derive(serde::Deserialize, Default)]
pub(super) struct DeployFunctionQuery {
    /// When this function is an **already-registered** federation subgraph, whether to refresh
    /// its registered SDL from the new version and block the deploy if the new schema no longer
    /// composes (default `true`). Set `false` to deploy without touching the registry — the
    /// escape hatch for a coordinated multi-subgraph migration.
    #[serde(default)]
    register_subgraph: Option<bool>,
}

/// Invoke `f` with the bytes of every `boatramp:function-manifest` custom section in a
/// component — descending into its embedded core module(s), where the guest's `#[link_section]`
/// manifest lives. Best-effort: a malformed component just yields nothing.
#[cfg(feature = "handlers")]
fn scan_manifest_sections(bytes: &[u8], f: &mut impl FnMut(&[u8])) {
    use wasmparser::{Parser, Payload};
    for payload in Parser::new(0).parse_all(bytes) {
        match payload {
            Ok(Payload::CustomSection(reader)) if reader.name() == "boatramp:function-manifest" => {
                f(reader.data());
            }
            Ok(Payload::ModuleSection {
                unchecked_range, ..
            }) => scan_manifest_sections(&bytes[unchecked_range], f),
            Ok(_) => {}
            Err(_) => return,
        }
    }
}

/// Whether a component **self-declares** a GraphQL federation subgraph: any NDJSON line of its
/// `boatramp:function-manifest` section carries `"subgraph": true` (the shim's
/// `#[graphql_subgraph]` emits this). This is the intent signal that lets a first deploy
/// auto-register the subgraph — a function that does not declare it is never touched.
#[cfg(feature = "handlers")]
fn component_declares_subgraph(component: &[u8]) -> bool {
    let mut declared = false;
    scan_manifest_sections(component, &mut |data| {
        for line in data.split(|&b| b == b'\n') {
            if let Ok(v) = serde_json::from_slice::<serde_json::Value>(line) {
                if v.get("subgraph").and_then(serde_json::Value::as_bool) == Some(true) {
                    declared = true;
                }
            }
        }
    });
    declared
}

/// Whether a component's `boatramp:function-manifest` self-declares that the route with request
/// path `route` is a **streaming** handler (`#[handler(stream)]` emits `"streaming": true` on that
/// function's manifest line). Matches by the http trigger's path (the part after an optional
/// `METHOD `), so a multi-route component reports per route. Returns `false` when no line matches
/// or none declares streaming — including for a guest built before the flag existed.
#[cfg(feature = "handlers")]
pub(crate) fn component_declares_streaming_route(component: &[u8], route: &str) -> bool {
    let mut declared = false;
    scan_manifest_sections(component, &mut |data| {
        for line in data.split(|&b| b == b'\n') {
            let Ok(v) = serde_json::from_slice::<serde_json::Value>(line) else {
                continue;
            };
            if v.get("streaming").and_then(serde_json::Value::as_bool) != Some(true) {
                continue;
            }
            // This line is streaming — does one of its http triggers target `route`?
            let Some(triggers) = v.get("triggers").and_then(serde_json::Value::as_array) else {
                continue;
            };
            for t in triggers {
                if t.get("on").and_then(serde_json::Value::as_str) != Some("http") {
                    continue;
                }
                if let Some(r) = t.get("route").and_then(serde_json::Value::as_str) {
                    // `route` is `"METHOD /path"` or `"/path"`; compare the path portion.
                    let path = r.rsplit(char::is_whitespace).next().unwrap_or(r);
                    if path == route {
                        declared = true;
                    }
                }
            }
        }
    });
    declared
}

/// The stability of a capability feature — an honest, present-tense signal to operators and
/// guest authors, and the seam the future deprecation clock extends (a deprecated capability is
/// just this with a removal target). `Experimental` = new or off-by-default surface whose shape
/// or behaviour may still change; `Stable` = safe to build on. Not a quality judgement — a
/// stable capability isn't "better", it's *settled*.
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "lowercase")]
pub enum Lifecycle {
    Stable,
    Experimental,
}

impl Lifecycle {
    /// Lowercase label for human output (matches the JSON serialization).
    #[must_use]
    pub fn as_str(self) -> &'static str {
        match self {
            Self::Stable => "stable",
            Self::Experimental => "experimental",
        }
    }
}

/// A capability feature this host implements, paired with its stability. The `name` is the token
/// a guest names in its manifest `requires`; admission checks the name, and `boatramp
/// capabilities` shows the name + lifecycle so operators can see what's settled vs. provisional.
#[derive(Debug, Clone, serde::Serialize)]
pub struct CapabilityFeature {
    pub name: &'static str,
    pub lifecycle: Lifecycle,
}

/// The capability **features** this host build implements, with lifecycle — what a guest's
/// manifest `requires` is checked against. The base grantable capabilities are always present
/// with the handler engine (the `KNOWN_IMPORTS` tokens, all settled); the granular surface
/// features are always-on in 0.3.0 except the correlated roll-up, which is cargo-gated. This is
/// the admission side of the contract: availability lives in metadata, not the linkable WIT
/// (PLAN v2).
#[cfg(feature = "handlers")]
pub fn host_capability_features_detailed() -> Vec<CapabilityFeature> {
    use Lifecycle::{Experimental, Stable};
    // Base grantable capabilities (the KNOWN_IMPORTS tokens) — the established interface grants.
    let mut f: Vec<CapabilityFeature> = boatramp_core::config::known_imports()
        .iter()
        .map(|&name| CapabilityFeature {
            name,
            lifecycle: Stable,
        })
        .collect();
    // Surface features beyond the base grants.
    f.push(CapabilityFeature {
        name: "sql-json",
        lifecycle: Stable,
    });
    // pgvector `distance` is new and Postgres-only (fail-closed elsewhere); the vector surface is
    // the most likely to grow more operators/index hints — flagged experimental until it settles.
    f.push(CapabilityFeature {
        name: "orm-vector",
        lifecycle: Experimental,
    });
    f.push(CapabilityFeature {
        name: "streaming",
        lifecycle: Stable,
    });
    if cfg!(feature = "orm-subquery") {
        // Correlated roll-ups ship off-by-default (the riskiest query surface) — experimental
        // until the shape settles.
        f.push(CapabilityFeature {
            name: "orm-subquery",
            lifecycle: Experimental,
        });
    }
    f
}

/// The capability feature **names** this host implements — what a guest manifest `requires` is
/// checked against. Names only; [`host_capability_features_detailed`] pairs them with lifecycle.
#[cfg(feature = "handlers")]
pub fn host_capability_features() -> Vec<&'static str> {
    host_capability_features_detailed()
        .into_iter()
        .map(|c| c.name)
        .collect()
}

/// The capability features a component's `boatramp:function-manifest` **requires** (any NDJSON
/// line's `"requires": [...]`), deduped. A guest that uses a capability whose availability varies
/// by host build declares it here so the deploy can fail loud on a host that lacks it.
#[cfg(feature = "handlers")]
pub fn component_requires(component: &[u8]) -> Vec<String> {
    let mut reqs = Vec::new();
    scan_manifest_sections(component, &mut |data| {
        for line in data.split(|&b| b == b'\n') {
            if let Ok(v) = serde_json::from_slice::<serde_json::Value>(line) {
                if let Some(arr) = v.get("requires").and_then(serde_json::Value::as_array) {
                    reqs.extend(arr.iter().filter_map(|r| r.as_str().map(str::to_string)));
                }
            }
        }
    });
    reqs.sort();
    reqs.dedup();
    reqs
}

/// The capability features a component `requires` that this host does **not** implement — empty
/// when the host can satisfy the component. A non-empty result is a fail-loud deploy rejection.
#[cfg(feature = "handlers")]
pub fn unmet_requires(component: &[u8]) -> Vec<String> {
    let host = host_capability_features();
    component_requires(component)
        .into_iter()
        .filter(|r| !host.contains(&r.as_str()))
        .collect()
}

/// Keep the project's GraphQL supergraph correct across a function deploy. The function is a
/// subgraph to (re)register when it is **already registered** *or* its component
/// **self-declares** one (the shim marker); in either case introspect the **pending** version's
/// `_service { sdl }` before its activation flips and **block** the deploy (an error response) if
/// the new schema does not compose. So a subgraph auto-registers on first deploy, refreshes on
/// each later deploy, and can never leave the supergraph stale or broken. An ordinary function
/// (no registry entry, no marker) is untouched, `?register_subgraph=false` opts out, and a node
/// with no engine degrades to a skip. `Ok(())` ⇒ proceed with the deploy.
#[cfg(feature = "handlers")]
async fn maybe_register_subgraph(
    deploy: &DeployStore,
    handlers: &HandlerRuntime,
    project: boatramp_core::project::ProjectRef<'_>,
    name: &str,
    function: &boatramp_core::function::Function,
    component: &str,
    register: Option<bool>,
) -> Result<(), Response> {
    if register == Some(false) {
        return Ok(()); // explicit opt-out (the coordinated-migration escape hatch)
    }
    let kv = deploy.kv().as_ref();
    if !crate::graphql_registry::is_registered_subgraph(kv, project.as_str(), name).await {
        // First deploy: only auto-register a component that declares itself a subgraph; any
        // ordinary function (or an unreadable blob) deploys untouched.
        match crate::handler_dispatch::read_blob_fully(deploy, component).await {
            Ok(blob) if component_declares_subgraph(&blob) => {}
            _ => return Ok(()),
        }
    }
    let sdl = match handlers
        .introspect_subgraph_sdl(deploy, project, function, component)
        .await
    {
        Ok(sdl) => sdl,
        // No engine on this node — skip rather than block; the SDL simply isn't (re)published.
        Err(crate::function_runtime::SubgraphSdlError::Unavailable) => return Ok(()),
        Err(crate::function_runtime::SubgraphSdlError::NotASubgraph) => {
            return Err((
                StatusCode::UNPROCESSABLE_ENTITY,
                format!(
                    "subgraph `{name}` does not answer `{{ _service {{ sdl }} }}`; deploy with \
                     `?register_subgraph=false` to skip subgraph registration\n"
                ),
            )
                .into_response())
        }
        Err(crate::function_runtime::SubgraphSdlError::InvokeFailed(msg)) => {
            return Err((
                StatusCode::BAD_GATEWAY,
                format!("could not introspect subgraph `{name}`: {msg}\n"),
            )
                .into_response())
        }
    };
    match crate::graphql_registry::publish(kv, project.as_str(), name, &sdl).await {
        Ok(_) => Ok(()),
        Err(crate::graphql_registry::PublishError::Composition(e)) => Err((
            StatusCode::BAD_REQUEST,
            format!(
                "subgraph `{name}` does not compose: {e}\n(deploy with `?register_subgraph=false` \
                 to skip, or unregister a conflicting subgraph first)\n"
            ),
        )
            .into_response()),
        Err(crate::graphql_registry::PublishError::Store(e)) => Err((
            StatusCode::INTERNAL_SERVER_ERROR,
            format!("registry store error: {e}\n"),
        )
            .into_response()),
    }
}

/// No wasm engine in this build → no subgraph registry to maintain; the deploy proceeds unchanged.
#[cfg(not(feature = "handlers"))]
async fn maybe_register_subgraph(
    _deploy: &DeployStore,
    _handlers: &HandlerRuntime,
    _project: boatramp_core::project::ProjectRef<'_>,
    _name: &str,
    _function: &boatramp_core::function::Function,
    _component: &str,
    _register: Option<bool>,
) -> Result<(), Response> {
    Ok(())
}

/// `PUT /api/functions/:name` (FA-2) — deploy a version of a top-level function.
/// The component blob must already be uploaded. Creates the function if new;
/// otherwise appends + activates the version (idempotent per component hash).
/// `system·admin`.
pub(super) async fn deploy_function(
    State(deploy): State<DeployStore>,
    Extension(project): axum::extract::Extension<ProjectContext>,
    Extension(handlers): Extension<Arc<HandlerRuntime>>,
    axum::extract::Query(q): axum::extract::Query<DeployFunctionQuery>,
    Path(name): Path<String>,
    Json(body): Json<FunctionUpsert>,
) -> Response {
    use boatramp_core::function::{Function, Owner};
    if let Some(resp) = reject_invalid_name("function", &name) {
        return resp;
    }
    match deploy.has_blob(&body.component).await {
        Ok(true) => {}
        Ok(false) => {
            return (
                StatusCode::BAD_REQUEST,
                format!("component blob {} not uploaded\n", body.component),
            )
                .into_response()
        }
        Err(err) => return deploy_error_response(err),
    }
    let now = now_unix();
    let f = match deploy.get_function(project.as_ref(), &name).await {
        Ok(Some(mut existing)) => {
            existing.config = body.config;
            existing.upsert_version(&body.component, body.lifecycle, now);
            existing
        }
        // A brand-new top-level function is owned by the (single, for now) default
        // project; per-tenant ownership arrives with FA-4.
        Ok(None) => Function::new(
            name.clone(),
            Owner::Project("default".to_string()),
            &body.component,
            body.config,
            body.lifecycle,
            now,
        ),
        Err(err) => return deploy_error_response(err),
    };
    // Before the new version becomes active: if this function is (or self-declares) a federation
    // subgraph, (re)register its SDL and refuse the deploy if the new schema does not compose with
    // the project's supergraph (a deploy must never leave the supergraph invalid or stale).
    if let Err(resp) = maybe_register_subgraph(
        &deploy,
        &handlers,
        project.as_ref(),
        &name,
        &f,
        &body.component,
        q.register_subgraph,
    )
    .await
    {
        return resp;
    }
    if let Err(err) = deploy.put_function(project.as_ref(), &f).await {
        return deploy_error_response(err);
    }
    Json(f).into_response()
}

/// Body of `POST /api/functions/:name/rollback`.
#[derive(serde::Deserialize)]
pub(super) struct RollbackBody {
    pub(super) to: String,
}

/// `POST /api/functions/:name/rollback` (FA-2) — point active at a prior version.
pub(super) async fn rollback_function(
    State(deploy): State<DeployStore>,
    Extension(project): axum::extract::Extension<ProjectContext>,
    Path(name): Path<String>,
    Json(body): Json<RollbackBody>,
) -> Response {
    match deploy.get_function(project.as_ref(), &name).await {
        Ok(Some(mut f)) => match f.rollback(&body.to) {
            Ok(()) => {
                if let Err(err) = deploy.put_function(project.as_ref(), &f).await {
                    return deploy_error_response(err);
                }
                Json(f).into_response()
            }
            Err(msg) => (StatusCode::BAD_REQUEST, format!("{msg}\n")).into_response(),
        },
        Ok(None) => (StatusCode::NOT_FOUND, format!("no function {name:?}\n")).into_response(),
        Err(err) => deploy_error_response(err),
    }
}

/// Body of `PUT /api/functions/:name/aliases/:label`.
#[derive(serde::Deserialize)]
pub(super) struct AliasBody {
    pub(super) version: String,
}

/// `PUT /api/functions/:name/aliases/:label` (FA-2) — point a label at a version.
pub(super) async fn alias_function(
    State(deploy): State<DeployStore>,
    Extension(project): axum::extract::Extension<ProjectContext>,
    Path((name, label)): Path<(String, String)>,
    Json(body): Json<AliasBody>,
) -> Response {
    match deploy.get_function(project.as_ref(), &name).await {
        Ok(Some(mut f)) => match f.set_alias(&label, &body.version) {
            Ok(()) => {
                if let Err(err) = deploy.put_function(project.as_ref(), &f).await {
                    return deploy_error_response(err);
                }
                Json(f).into_response()
            }
            Err(msg) => (StatusCode::BAD_REQUEST, format!("{msg}\n")).into_response(),
        },
        Ok(None) => (StatusCode::NOT_FOUND, format!("no function {name:?}\n")).into_response(),
        Err(err) => deploy_error_response(err),
    }
}

/// `DELETE /api/functions/:name` (FA-2) — remove a top-level function (idempotent).
/// Content-addressed component blobs are shared and left to `prune`.
pub(super) async fn remove_function(
    State(deploy): State<DeployStore>,
    Extension(project): axum::extract::Extension<ProjectContext>,
    Path(name): Path<String>,
) -> Response {
    match deploy.delete_function(project.as_ref(), &name).await {
        Ok(_) => StatusCode::NO_CONTENT.into_response(),
        Err(err) => deploy_error_response(err),
    }
}

#[cfg(all(test, feature = "handlers"))]
mod tests {
    use super::*;
    use boatramp_core::function::{Function, FunctionConfig, Lifecycle, Owner};
    use boatramp_core::kv::MemoryKv;
    use std::sync::Arc;

    #[test]
    fn host_capability_features_registry_and_requires_filter() {
        let host = host_capability_features();
        // Base grantable capabilities (KNOWN_IMPORTS) + always-on surface features are advertised.
        assert!(host.contains(&"sql"), "base capability token present");
        assert!(
            host.contains(&"streaming"),
            "always-on surface feature present"
        );
        assert!(host.contains(&"orm-vector"));
        // The correlated roll-up is cargo-gated: advertised iff this build enabled it.
        assert_eq!(
            host.contains(&"orm-subquery"),
            cfg!(feature = "orm-subquery")
        );
        // The detailed registry pairs each name with a lifecycle, and its names are exactly the
        // flat list (one source of truth — the flat list derives from the detailed one).
        let detailed = host_capability_features_detailed();
        let detailed_names: Vec<&str> = detailed.iter().map(|c| c.name).collect();
        assert_eq!(
            detailed_names, host,
            "detailed names match the flat registry"
        );
        let lifecycle = |name: &str| {
            detailed
                .iter()
                .find(|c| c.name == name)
                .map(|c| c.lifecycle)
        };
        assert_eq!(lifecycle("sql"), Some(super::Lifecycle::Stable));
        assert_eq!(lifecycle("sql-json"), Some(super::Lifecycle::Stable));
        assert_eq!(
            lifecycle("orm-vector"),
            Some(super::Lifecycle::Experimental)
        );
        // The admission filter keeps only requirements the host cannot satisfy.
        let unmet: Vec<&str> = ["sql", "streaming", "quantum-teleport", "warp-drive"]
            .into_iter()
            .filter(|r| !host.contains(r))
            .collect();
        assert_eq!(unmet, vec!["quantum-teleport", "warp-drive"]);
    }

    /// A blob store the subgraph-refresh guard never reaches (it returns before touching blobs).
    struct NullStorage;
    #[async_trait::async_trait]
    impl boatramp_core::Storage for NullStorage {
        async fn get(
            &self,
            _: &str,
        ) -> Result<boatramp_core::GetObject, boatramp_core::StorageError> {
            Err(boatramp_core::StorageError::NotFound(String::new()))
        }
        async fn get_range(
            &self,
            _: &str,
            _: u64,
            _: Option<u64>,
        ) -> Result<boatramp_core::GetObject, boatramp_core::StorageError> {
            Err(boatramp_core::StorageError::NotFound(String::new()))
        }
        async fn put(
            &self,
            _: &str,
            _: boatramp_core::ByteStream,
            _: boatramp_core::PutMeta,
        ) -> Result<boatramp_core::ObjectMeta, boatramp_core::StorageError> {
            Err(boatramp_core::StorageError::unsupported("null"))
        }
        async fn head(
            &self,
            _: &str,
        ) -> Result<boatramp_core::ObjectMeta, boatramp_core::StorageError> {
            Err(boatramp_core::StorageError::NotFound(String::new()))
        }
        async fn delete(&self, _: &str) -> Result<(), boatramp_core::StorageError> {
            Ok(())
        }
        async fn list(
            &self,
            _: &str,
        ) -> Result<Vec<boatramp_core::ObjectMeta>, boatramp_core::StorageError> {
            Ok(Vec::new())
        }
    }

    fn a_function() -> Function {
        Function::new(
            "accounts",
            Owner::Project("default".to_string()),
            "component-hash",
            FunctionConfig::default(),
            Lifecycle::default(),
            0,
        )
    }

    /// The subgraph-refresh hook must never block or touch the registry for a function that is
    /// not a registered subgraph, on an explicit opt-out, or on a node with no wasm engine — so
    /// an ordinary function deploy (and the coordinated-migration escape hatch) is unaffected.
    #[tokio::test]
    async fn refresh_is_a_noop_unless_the_function_is_a_registered_subgraph() {
        let deploy = DeployStore::new(Arc::new(NullStorage), Arc::new(MemoryKv::new()));
        let handlers = HandlerRuntime::disabled();
        let project = boatramp_core::project::ProjectRef::new("default");
        let f = a_function();

        // Not a registered subgraph → no-op; nothing is published.
        maybe_register_subgraph(
            &deploy,
            &handlers,
            project,
            "accounts",
            &f,
            "component-hash",
            None,
        )
        .await
        .expect("an unregistered function deploys freely");
        assert!(
            !crate::graphql_registry::is_registered_subgraph(
                deploy.kv().as_ref(),
                "default",
                "accounts"
            )
            .await
        );

        // Now registered: `?register_subgraph=false` opts out (the migration escape hatch).
        crate::graphql_registry::publish(
            deploy.kv().as_ref(),
            "default",
            "accounts",
            "type Query { x: Int }",
        )
        .await
        .unwrap();
        maybe_register_subgraph(
            &deploy,
            &handlers,
            project,
            "accounts",
            &f,
            "component-hash",
            Some(false),
        )
        .await
        .expect("opt-out never blocks");

        // Registered, no opt-out, but this node has no engine → Unavailable degrades to a skip
        // rather than blocking the deploy.
        maybe_register_subgraph(
            &deploy,
            &handlers,
            project,
            "accounts",
            &f,
            "component-hash",
            None,
        )
        .await
        .expect("a node with no engine skips the refresh, it does not block");
    }

    /// A minimal core wasm module carrying one `boatramp:function-manifest` custom section — the
    /// shape the guest's `#[link_section]` manifest takes (here at the top level; a real
    /// component nests it in an embedded core module, exercised end-to-end elsewhere).
    fn leb128(mut n: usize, out: &mut Vec<u8>) {
        loop {
            let mut byte = (n & 0x7f) as u8;
            n >>= 7;
            if n != 0 {
                byte |= 0x80;
            }
            out.push(byte);
            if n == 0 {
                break;
            }
        }
    }

    fn module_with_manifest(manifest: &[u8]) -> Vec<u8> {
        let name = b"boatramp:function-manifest";
        let mut payload = Vec::new();
        leb128(name.len(), &mut payload);
        payload.extend_from_slice(name);
        payload.extend_from_slice(manifest);
        let mut module = vec![0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00]; // \0asm + version 1
        module.push(0x00); // custom section id
        leb128(payload.len(), &mut module);
        module.extend_from_slice(&payload);
        module
    }

    #[test]
    fn a_subgraph_marker_in_the_manifest_is_detected() {
        assert!(component_declares_subgraph(&module_with_manifest(
            br#"{"name":"schema","triggers":[{"on":"http","route":"POST /graphql"}],"authorize":"public","subgraph":true}"#
        )));
        // An ordinary managed handler manifest is not a subgraph.
        assert!(!component_declares_subgraph(&module_with_manifest(
            br#"{"name":"orders","authorize":"tenant"}"#
        )));
        // No manifest section at all → not a subgraph.
        assert!(!component_declares_subgraph(&[
            0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00
        ]));
        // Garbage bytes are handled gracefully (best-effort parse).
        assert!(!component_declares_subgraph(b"not a wasm module"));
    }
}