feat(vars): VarsService + vars:: SDK + config capabilities

Scripts can now read group-inherited config via vars::get(key) / vars::all().

- shared: VarsService trait (read-only get/all) + NoopVarsService; added as
  the 14th field on the Services bundle.
- manager-core: VarsServiceImpl resolves the calling app's config via
  config_resolver (derives app_id from cx.app_id; AppVarsRead-gated for
  authed principals, script-as-gate for anon).
- executor-core: vars:: Rhai bridge (get/all), registered in the SDK.
- authz: AppVarsRead/Write, GroupVarsRead/Write, GroupSecretsRead/Write
  capabilities (group caps resolve via the Phase-2 ancestor walk; the
  GroupSecretsRead human-read gate is group_admin-only, distinct from an
  app's runtime injection).
- wired VarsServiceImpl into the picloud binary; updated the executor-core
  test Services::new call sites.

386 manager-core lib tests green; clippy clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/executor-core/src/sdk/mod.rs

@@ -26,6 +26,7 @@ pub mod retry;
 pub mod secrets;
 pub mod stdlib;
 pub mod users;
+pub mod vars;
 
 pub use bridge::{dynamic_to_json, json_to_dynamic};
 pub use cx::SdkCallCx;
@@ -62,6 +63,7 @@ pub fn register_all(
     queue::register(engine, services, cx.clone());
     retry::register(engine, services, cx.clone());
     secrets::register(engine, services, cx.clone());
+    vars::register(engine, services, cx.clone());
     email::register(engine, services, cx.clone());
     users::register(engine, services, cx.clone());
     invoke::register(engine, services, cx, limits, self_engine);

crates/executor-core/src/sdk/vars.rs

@@ -0,0 +1,57 @@
+//! `vars::` Rhai bridge — read-only access to the app's resolved,
+//! group-inherited config (Phase 3).
+//!
+//! ```rhai
+//! let region = vars::get("region");   // value or ()
+//! let all = vars::all();              // #{ key: value, ... }
+//! ```
+//!
+//! Values are inherited down the group tree and env-filtered (§3); the
+//! resolution happens server-side in manager-core. Writes go through the
+//! admin API, not the SDK. `app_id` is derived from `cx.app_id` in the
+//! service — never a script argument — preserving cross-app isolation.
+
+use std::sync::Arc;
+
+use picloud_shared::{SdkCallCx, Services};
+use rhai::{Dynamic, Engine as RhaiEngine, EvalAltResult, Map, Module};
+
+use super::bridge::{block_on, json_to_dynamic};
+
+pub(super) fn register(engine: &mut RhaiEngine, services: &Services, cx: Arc<SdkCallCx>) {
+    let svc = services.vars.clone();
+    let mut module = Module::new();
+
+    // vars::get(key) — resolved value, or () if no level defines it.
+    {
+        let svc = svc.clone();
+        let cx = cx.clone();
+        module.set_native_fn(
+            "get",
+            move |key: &str| -> Result<Dynamic, Box<EvalAltResult>> {
+                let svc = svc.clone();
+                let cx = cx.clone();
+                let opt = block_on("vars", async move { svc.get(&cx, key).await })?;
+                Ok(opt.map_or(Dynamic::UNIT, json_to_dynamic))
+            },
+        );
+    }
+
+    // vars::all() — the fully-resolved config map.
+    {
+        let svc = svc.clone();
+        let cx = cx.clone();
+        module.set_native_fn("all", move || -> Result<Map, Box<EvalAltResult>> {
+            let svc = svc.clone();
+            let cx = cx.clone();
+            let resolved = block_on("vars", async move { svc.all(&cx).await })?;
+            let mut m = Map::new();
+            for (k, v) in resolved {
+                m.insert(k.into(), json_to_dynamic(v));
+            }
+            Ok(m)
+        });
+    }
+
+    engine.register_static_module("vars", module.into());
+}

crates/executor-core/tests/module_redaction_logging.rs

@@ -107,6 +107,7 @@ async fn original_backend_error_is_logged_at_error_level() {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     let engine = Engine::new(Limits::default(), services);
 

crates/executor-core/tests/modules.rs

@@ -104,6 +104,7 @@ fn services_with(modules: Arc<dyn ModuleSource>) -> Services {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     )
 }
 

crates/executor-core/tests/sdk_docs.rs

@@ -235,6 +235,7 @@ fn make_engine() -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_email.rs

@@ -44,6 +44,7 @@ fn engine_with(rec: Arc<RecordingEmail>) -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_files.rs

@@ -172,6 +172,7 @@ fn make_engine() -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_http.rs

@@ -95,6 +95,7 @@ fn engine_with(http: Arc<dyn HttpService>) -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_invoke.rs

@@ -90,6 +90,7 @@ fn build_engine(svc: Arc<FakeInvokeService>) -> Arc<Engine> {
         Arc::new(NoopUsersService),
         Arc::new(NoopQueueService),
         svc,
+        Arc::new(picloud_shared::NoopVarsService),
     );
     let engine = Arc::new(Engine::new(Limits::default(), services));
     engine.set_self_weak(Arc::downgrade(&engine));

crates/executor-core/tests/sdk_kv.rs

@@ -114,6 +114,7 @@ fn make_engine() -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_pubsub.rs

@@ -52,6 +52,7 @@ fn make_engine(svc: Arc<RecordingPubsub>) -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_queue.rs

@@ -66,6 +66,7 @@ fn make_engine(svc: Arc<RecordingQueue>) -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         svc,
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_retry.rs

@@ -30,6 +30,7 @@ fn build_engine() -> Arc<Engine> {
         Arc::new(NoopUsersService),
         Arc::new(NoopQueueService),
         Arc::new(NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_secrets.rs

@@ -105,6 +105,7 @@ fn make_engine() -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/executor-core/tests/sdk_subscriber_token.rs

@@ -99,6 +99,7 @@ fn make_engine() -> Arc<Engine> {
         Arc::new(picloud_shared::NoopUsersService),
         Arc::new(picloud_shared::NoopQueueService),
         Arc::new(picloud_shared::NoopInvokeService),
+        Arc::new(picloud_shared::NoopVarsService),
     );
     Arc::new(Engine::new(Limits::default(), services))
 }

crates/manager-core/src/authz.rs

@@ -116,6 +116,25 @@ pub enum Capability {
     /// Write (set/delete) a secret in this app's secrets store (v1.1.7).
     /// Granted to `editor`+, maps to `script:write` on API keys.
     AppSecretsWrite(AppId),
+    /// Read this app's resolved config vars (Phase 3). Same trust shape as
+    /// secrets-read — granted to `viewer`+, maps to `script:read`.
+    AppVarsRead(AppId),
+    /// Write (set/delete) an app-owned config var (Phase 3). Granted to
+    /// `editor`+, maps to `script:write`.
+    AppVarsWrite(AppId),
+    /// Read a group's config vars (Phase 3). Resolved via the group
+    /// ancestor walk; viewer+ on the group.
+    GroupVarsRead(GroupId),
+    /// Write (set/delete) a group-owned config var (Phase 3). editor+ on
+    /// the group.
+    GroupVarsWrite(GroupId),
+    /// Read a group-owned secret's VALUE (Phase 3, the human-read gate).
+    /// group_admin on the owning group — distinct from runtime injection,
+    /// which an inheriting app does without this check.
+    GroupSecretsRead(GroupId),
+    /// Write (set/delete) a group-owned secret (Phase 3). editor+ on the
+    /// group.
+    GroupSecretsWrite(GroupId),
     /// Send an outbound email from a script in this app (v1.1.7). Maps
     /// to `script:write` on API keys (sending mail is an outbound
     /// side-effect like an HTTP request). Granted to `editor`+.
@@ -176,7 +195,11 @@ impl Capability {
             // app) is denied group management at the binding layer.
             | Self::GroupRead(_)
             | Self::GroupWrite(_)
-            | Self::GroupAdmin(_) => None,
+            | Self::GroupAdmin(_)
+            | Self::GroupVarsRead(_)
+            | Self::GroupVarsWrite(_)
+            | Self::GroupSecretsRead(_)
+            | Self::GroupSecretsWrite(_) => None,
             Self::AppRead(id)
             | Self::AppWriteScript(id)
             | Self::AppWriteRoute(id)
@@ -194,6 +217,8 @@ impl Capability {
             | Self::AppQueueEnqueue(id)
             | Self::AppSecretsRead(id)
             | Self::AppSecretsWrite(id)
+            | Self::AppVarsRead(id)
+            | Self::AppVarsWrite(id)
             | Self::AppEmailSend(id)
             | Self::AppManageTriggers(id)
             | Self::AppDeadLetterManage(id)
@@ -223,7 +248,9 @@ impl Capability {
             | Self::AppFilesRead(_)
             | Self::AppSecretsRead(_)
             | Self::AppUsersRead(_)
-            | Self::GroupRead(_) => Scope::ScriptRead,
+            | Self::AppVarsRead(_)
+            | Self::GroupRead(_)
+            | Self::GroupVarsRead(_) => Scope::ScriptRead,
             Self::AppWriteScript(_)
             | Self::AppKvWrite(_)
             | Self::AppDocsWrite(_)
@@ -235,6 +262,7 @@ impl Capability {
             | Self::AppEmailSend(_)
             | Self::AppUsersWrite(_)
             | Self::AppUsersAdmin(_)
+            | Self::AppVarsWrite(_)
             | Self::AppInvoke(_) => Scope::ScriptWrite,
             Self::AppWriteRoute(_) => Scope::RouteWrite,
             Self::AppManageDomains(_) => Scope::DomainManage,
@@ -243,7 +271,10 @@ impl Capability {
             | Self::AppDeadLetterManage(_)
             | Self::AppTopicManage(_)
             | Self::GroupWrite(_)
-            | Self::GroupAdmin(_) => Scope::AppAdmin,
+            | Self::GroupAdmin(_)
+            | Self::GroupVarsWrite(_)
+            | Self::GroupSecretsRead(_)
+            | Self::GroupSecretsWrite(_) => Scope::AppAdmin,
             Self::AppLogRead(_) => Scope::LogRead,
         }
     }
@@ -412,7 +443,13 @@ async fn role_grants(
             // walk (a group_admin on an ancestor is implicitly admin of
             // the descendant group). Routed before member_grants because
             // group caps carry no app_id.
-            Capability::GroupRead(g) | Capability::GroupWrite(g) | Capability::GroupAdmin(g) => {
+            Capability::GroupRead(g)
+            | Capability::GroupWrite(g)
+            | Capability::GroupAdmin(g)
+            | Capability::GroupVarsRead(g)
+            | Capability::GroupVarsWrite(g)
+            | Capability::GroupSecretsRead(g)
+            | Capability::GroupSecretsWrite(g) => {
                 group_member_grants(repo, principal.user_id, cap, g).await
             }
             // Creating a root-level group is an instance act — members
@@ -472,9 +509,19 @@ async fn group_member_grants(
 /// viewer→read, editor→write, group_admin(=AppAdmin)→admin.
 const fn group_role_satisfies(role: AppRole, cap: Capability) -> bool {
     match cap {
-        Capability::GroupRead(_) => true, // any role can read
+        // viewer+ reads group metadata and config vars.
-        Capability::GroupWrite(_) => matches!(role, AppRole::Editor | AppRole::AppAdmin),
+        Capability::GroupRead(_) | Capability::GroupVarsRead(_) => true,
-        Capability::GroupAdmin(_) => matches!(role, AppRole::AppAdmin),
+        // editor+ writes config vars/secrets.
+        Capability::GroupWrite(_)
+        | Capability::GroupVarsWrite(_)
+        | Capability::GroupSecretsWrite(_) => {
+            matches!(role, AppRole::Editor | AppRole::AppAdmin)
+        }
+        // group_admin manages the group + reads secret VALUES (the
+        // human-read gate, distinct from an app's runtime injection).
+        Capability::GroupAdmin(_) | Capability::GroupSecretsRead(_) => {
+            matches!(role, AppRole::AppAdmin)
+        }
         _ => false,
     }
 }
@@ -493,6 +540,7 @@ const fn role_satisfies(role: AppRole, cap: Capability) -> bool {
             | Capability::AppFilesRead(_)
             | Capability::AppSecretsRead(_)
             | Capability::AppUsersRead(_)
+            | Capability::AppVarsRead(_)
     );
     let in_editor = in_viewer
         || matches!(
@@ -508,6 +556,7 @@ const fn role_satisfies(role: AppRole, cap: Capability) -> bool {
                 | Capability::AppSecretsWrite(_)
                 | Capability::AppEmailSend(_)
                 | Capability::AppUsersWrite(_)
+                | Capability::AppVarsWrite(_)
                 | Capability::AppInvoke(_)
         );
     let in_app_admin = in_editor

crates/manager-core/src/lib.rs

@@ -85,6 +85,7 @@ pub mod trigger_repo;
 pub mod triggers_api;
 pub mod users_admin_api;
 pub mod users_service;
+pub mod vars_service;
 
 pub use abandoned_repo::{
     AbandonedRepo, AbandonedRepoError, NewAbandonedExecution, PostgresAbandonedRepo,
@@ -220,3 +221,4 @@ pub use trigger_repo::{
 pub use triggers_api::{triggers_router, TriggersApiError, TriggersState};
 pub use users_admin_api::{app_users_router, AppUsersApiError, AppUsersState};
 pub use users_service::{UsersServiceConfig, UsersServiceImpl};
+pub use vars_service::VarsServiceImpl;

crates/manager-core/src/vars_service.rs

@@ -0,0 +1,63 @@
+//! `VarsService` — the runtime read path for group-inherited config.
+//!
+//! Resolves the calling app's config (own rows + inherited group rows,
+//! env-filtered, proximity-first; see `config_resolver`) and exposes it to
+//! scripts as `vars::get(key)` / `vars::all()`. Read-only from scripts;
+//! writes go through the admin API. Like every SDK service, it derives the
+//! app from `cx.app_id` — never a script argument — so cross-app isolation
+//! holds.
+
+use std::collections::BTreeMap;
+use std::sync::Arc;
+
+use async_trait::async_trait;
+use picloud_shared::{SdkCallCx, VarsError, VarsService};
+use serde_json::Value;
+use sqlx::PgPool;
+
+use crate::authz::{self, AuthzRepo, Capability};
+use crate::config_resolver::{fetch_var_candidates, resolve};
+
+pub struct VarsServiceImpl {
+    pool: PgPool,
+    authz: Arc<dyn AuthzRepo>,
+}
+
+impl VarsServiceImpl {
+    #[must_use]
+    pub fn new(pool: PgPool, authz: Arc<dyn AuthzRepo>) -> Self {
+        Self { pool, authz }
+    }
+
+    /// Authed principals need `AppVarsRead`; anonymous public-HTTP scripts
+    /// (`principal: None`) read freely under script-as-gate semantics.
+    async fn check_read(&self, cx: &SdkCallCx) -> Result<(), VarsError> {
+        if let Some(ref principal) = cx.principal {
+            authz::require(&*self.authz, principal, Capability::AppVarsRead(cx.app_id))
+                .await
+                .map_err(|_| VarsError::Forbidden)?;
+        }
+        Ok(())
+    }
+
+    async fn resolved(&self, cx: &SdkCallCx) -> Result<BTreeMap<String, Value>, VarsError> {
+        let candidates = fetch_var_candidates(&self.pool, cx.app_id)
+            .await
+            .map_err(|e| VarsError::Backend(e.to_string()))?;
+        let (values, _provenance) = resolve(candidates);
+        Ok(values)
+    }
+}
+
+#[async_trait]
+impl VarsService for VarsServiceImpl {
+    async fn get(&self, cx: &SdkCallCx, key: &str) -> Result<Option<Value>, VarsError> {
+        self.check_read(cx).await?;
+        Ok(self.resolved(cx).await?.remove(key))
+    }
+
+    async fn all(&self, cx: &SdkCallCx) -> Result<BTreeMap<String, Value>, VarsError> {
+        self.check_read(cx).await?;
+        self.resolved(cx).await
+    }
+}

crates/picloud/src/lib.rs

@@ -33,7 +33,7 @@ use picloud_manager_core::{
     PrincipalResolver, PubsubServiceImpl, RealtimeAuthorityImpl, RepoResolver, RouteAdminState,
     RouteRepository, SandboxCeiling, ScriptRepository, SecretsConfig, SecretsServiceImpl,
     SecretsState, SubscriberTokenConfig, TopicRepo, TopicsState, TriggerConfig, TriggerRepo,
-    TriggersState, UsersServiceConfig, UsersServiceImpl,
+    TriggersState, UsersServiceConfig, UsersServiceImpl, VarsServiceImpl,
 };
 use picloud_orchestrator_core::realtime::DEFAULT_GC_INTERVAL_SECS;
 use picloud_orchestrator_core::routing::{AppDomainTable, RouteTable};
@@ -322,6 +322,8 @@ pub async fn build_app(
         // under script-as-gate semantics.
         .with_authz(authz.clone()),
     );
+    let vars: Arc<dyn picloud_shared::VarsService> =
+        Arc::new(VarsServiceImpl::new(pool.clone(), authz.clone()));
     let services = Services::new(
         kv,
         docs,
@@ -336,6 +338,7 @@ pub async fn build_app(
         users.clone(),
         queue,
         invoke,
+        vars,
     );
     // v1.1.9: keep the invoke depth bound aligned with the dispatcher's
     // trigger-depth bound (same counter under the hood).

crates/shared/src/lib.rs

@@ -38,6 +38,7 @@ pub mod subscriber_token;
 pub mod trigger_event;
 pub mod users;
 pub mod validator;
+pub mod vars;
 pub mod version;
 
 /// serde `default` for `enabled`-style boolean fields that should default to
@@ -101,4 +102,5 @@ pub use users::{
     UsersService,
 };
 pub use validator::{ScriptValidator, ValidatedScript, ValidationError};
+pub use vars::{NoopVarsService, VarsError, VarsService};
 pub use version::{API_VERSION, PRODUCT_VERSION, SDK_VERSION, WIRE_VERSION};

crates/shared/src/services.rs

@@ -24,7 +24,8 @@ use crate::{
     KvService, ModuleSource, NoopDeadLetterService, NoopDocsService, NoopEmailService,
     NoopEventEmitter, NoopFilesService, NoopHttpService, NoopInvokeService, NoopKvService,
     NoopModuleSource, NoopPubsubService, NoopQueueService, NoopSecretsService, NoopUsersService,
-    PubsubService, QueueService, SecretsService, ServiceEventEmitter, UsersService,
+    NoopVarsService, PubsubService, QueueService, SecretsService, ServiceEventEmitter,
+    UsersService, VarsService,
 };
 
 /// SDK service bundle. See module docs for the lifecycle and the v1.1.x
@@ -107,6 +108,12 @@ pub struct Services {
     /// and `invoke_async()` (fire-and-forget through the outbox).
     /// Cross-app invokes are rejected at the service entry point.
     pub invoke: Arc<dyn InvokeService>,
+
+    /// Group-inherited, env-scoped config (Phase 3). Scripts get
+    /// read-only `vars::{get,all}`; values resolve down the group tree
+    /// (§3). Backed by `config_resolver` over Postgres in the picloud
+    /// binary; `NoopVarsService` in tests that don't read config.
+    pub vars: Arc<dyn VarsService>,
 }
 
 impl Services {
@@ -129,6 +136,7 @@ impl Services {
         users: Arc<dyn UsersService>,
         queue: Arc<dyn QueueService>,
         invoke: Arc<dyn InvokeService>,
+        vars: Arc<dyn VarsService>,
     ) -> Self {
         Self {
             kv,
@@ -144,6 +152,7 @@ impl Services {
             users,
             queue,
             invoke,
+            vars,
         }
     }
 
@@ -168,6 +177,7 @@ impl Services {
             Arc::new(NoopUsersService),
             Arc::new(NoopQueueService),
             Arc::new(NoopInvokeService),
+            Arc::new(NoopVarsService),
         )
     }
 }

crates/shared/src/vars.rs

@@ -0,0 +1,48 @@
+//! `vars::*` — read-only access from scripts to the app's resolved
+//! configuration (Phase 3). Values are inherited down the group tree and
+//! env-filtered per the §3 resolution rule; the resolution happens in
+//! manager-core (`config_resolver`). Writes go through the admin API, not
+//! the SDK — scripts only read.
+
+use std::collections::BTreeMap;
+
+use async_trait::async_trait;
+use serde_json::Value;
+
+use crate::SdkCallCx;
+
+#[derive(Debug, thiserror::Error)]
+pub enum VarsError {
+    /// Caller principal lacked `AppVarsRead`. Only raised when
+    /// `cx.principal.is_some()` (public-HTTP scripts skip the check —
+    /// script-as-gate).
+    #[error("forbidden")]
+    Forbidden,
+    /// Postgres unavailable, malformed row, etc.
+    #[error("vars backend error: {0}")]
+    Backend(String),
+}
+
+#[async_trait]
+pub trait VarsService: Send + Sync {
+    /// Resolve a single config key for the calling app's environment.
+    /// `None` if no level defines it (or a tombstone suppresses it).
+    async fn get(&self, cx: &SdkCallCx, key: &str) -> Result<Option<Value>, VarsError>;
+
+    /// The app's fully-resolved config map (every inherited + own key).
+    async fn all(&self, cx: &SdkCallCx) -> Result<BTreeMap<String, Value>, VarsError>;
+}
+
+/// All-noop fallback for engines that don't wire vars (tests). Every call
+/// surfaces an explicit error rather than silently returning empty.
+pub struct NoopVarsService;
+
+#[async_trait]
+impl VarsService for NoopVarsService {
+    async fn get(&self, _cx: &SdkCallCx, _key: &str) -> Result<Option<Value>, VarsError> {
+        Err(VarsError::Backend("vars is not wired in".into()))
+    }
+    async fn all(&self, _cx: &SdkCallCx) -> Result<BTreeMap<String, Value>, VarsError> {
+        Err(VarsError::Backend("vars is not wired in".into()))
+    }
+}