commit a85a49dfd51357a4483778b6f3d14dcace027490
Author: Ein Anderssono <einand@3gdev.com>
Date:   Tue Oct 20 11:24:52 2026 +0200

    Add isolated Luau rule engine service

diff --git a/.gitea/workflows/publish.yaml b/.gitea/workflows/publish.yaml
new file mode 100644
index 0000000..84566a7
--- /dev/null
+++ b/.gitea/workflows/publish.yaml
@@ -0,0 +1,134 @@
+name: Build and publish rule engine
+
+on:
+  push:
+    branches: [main]
+    tags: ["v*"]
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    runs-on: large
+    if: ${{ !startsWith(github.ref, 'refs/heads/') || !contains(github.event.head_commit.message, '[auto-version-bump]') }}
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.GITEA_TOKEN }}
+          persist-credentials: true
+
+      - name: Test and lint in the shared builder image
+        shell: bash
+        run: |
+          set -euo pipefail
+          docker run --rm \
+            --volume "$PWD:/src" \
+            --volume ai-spel-rule-engine-cargo:/src/target \
+            --workdir /src \
+            harbor.k3s.k0.nu/ai-spel/game-builder:rust1.89-v2 \
+            sh -c 'cargo generate-lockfile && cargo fmt --all && cargo fmt --all -- --check && cargo test --workspace && cargo clippy --locked --workspace --all-targets -- -D warnings'
+
+      - name: Bump version and create Git tag
+        id: bump
+        if: startsWith(github.ref, 'refs/heads/')
+        shell: bash
+        run: |
+          set -euo pipefail
+          git fetch origin main --quiet
+          test "$(git rev-parse origin/main)" = "$GITHUB_SHA"
+          version="$(python3 scripts/bump-release-version.py)"
+          git config user.name "Gitea Actions"
+          git config user.email "actions@users.noreply.gitea"
+          git add -u
+          git add Cargo.toml Cargo.lock deploy/helm/ai-spel-rule-engine/Chart.yaml deploy/argocd/application.yaml
+          git commit -m "Release $version [auto-version-bump]"
+          git tag -a "v$version" -m "v$version"
+          git push origin HEAD:main "refs/tags/v$version"
+          echo "version=$version" >> "$GITHUB_OUTPUT"
+
+      - name: Build and publish image and Helm chart
+        id: publish
+        if: ${{ startsWith(github.ref, 'refs/tags/') || steps.bump.outputs.version != '' }}
+        shell: bash
+        env:
+          HARBOR_USERNAME: ${{ secrets.HARBOR_USERNAME }}
+          HARBOR_PASSWORD: ${{ secrets.HARBOR_PASSWORD }}
+          AUTO_RELEASE_VERSION: ${{ steps.bump.outputs.version }}
+        run: |
+          set -euo pipefail
+          version="${AUTO_RELEASE_VERSION:-${GITHUB_REF_NAME#v}}"
+          printf '%s' "$HARBOR_PASSWORD" | docker login harbor.k3s.k0.nu --username "$HARBOR_USERNAME" --password-stdin
+          image="harbor.k3s.k0.nu/ai-spel/rule-engine:$version"
+          docker build --platform linux/amd64 --pull --tag "$image" .
+          docker image push "$image"
+          helm_version=v3.17.3
+          if ! command -v helm >/dev/null 2>&1; then
+            mkdir -p "$RUNNER_TEMP/helm" "$HOME/.local/bin"
+            archive="helm-${helm_version}-linux-amd64.tar.gz"
+            curl -fsSLo "$RUNNER_TEMP/helm/$archive" "https://get.helm.sh/$archive"
+            curl -fsSLo "$RUNNER_TEMP/helm/$archive.sha256sum" "https://get.helm.sh/$archive.sha256sum"
+            (cd "$RUNNER_TEMP/helm" && sha256sum -c "$archive.sha256sum")
+            tar -xzf "$RUNNER_TEMP/helm/$archive" -C "$RUNNER_TEMP/helm"
+            install "$RUNNER_TEMP/helm/linux-amd64/helm" "$HOME/.local/bin/helm"
+            echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+            export PATH="$HOME/.local/bin:$PATH"
+          fi
+          helm lint deploy/helm/ai-spel-rule-engine
+          package_dir="$(mktemp -d)"
+          trap 'rm -rf "$package_dir"' EXIT
+          helm package deploy/helm/ai-spel-rule-engine --destination "$package_dir" --version "$version" --app-version "$version"
+          printf '%s' "$HARBOR_PASSWORD" | helm registry login harbor.k3s.k0.nu --username "$HARBOR_USERNAME" --password-stdin
+          helm push "$package_dir/ai-spel-rule-engine-$version.tgz" oci://harbor.k3s.k0.nu/ai-spel
+          helm template ai-spel-rule-engine "$package_dir/ai-spel-rule-engine-$version.tgz" --namespace ai-spel > "$package_dir/manifest.yaml"
+          oras_version=1.2.3
+          mkdir -p "$RUNNER_TEMP/oras"
+          curl -fsSLo "$RUNNER_TEMP/oras/oras.tgz" "https://github.com/oras-project/oras/releases/download/v${oras_version}/oras_${oras_version}_linux_amd64.tar.gz"
+          echo 'b4efc97a91f471f323f193ea4b4d63d8ff443ca3aab514151a30751330852827  '"$RUNNER_TEMP/oras/oras.tgz" | sha256sum -c -
+          tar -xzf "$RUNNER_TEMP/oras/oras.tgz" -C "$RUNNER_TEMP/oras" oras
+          install "$RUNNER_TEMP/oras/oras" "$RUNNER_TEMP/oras-bin"
+          printf '%s' "$HARBOR_PASSWORD" | "$RUNNER_TEMP/oras-bin" login harbor.k3s.k0.nu --username "$HARBOR_USERNAME" --password-stdin
+          unset HARBOR_PASSWORD
+          "$RUNNER_TEMP/oras-bin" push --artifact-type application/vnd.ai-spel.kubernetes-manifest.v1 \
+            "harbor.k3s.k0.nu/ai-spel/rule-engine-manifest:$version" \
+            "$package_dir/manifest.yaml:application/yaml"
+          echo "version=$version" >> "$GITHUB_OUTPUT"
+
+      - name: Deploy rule engine through Argo CD
+        if: ${{ startsWith(github.ref, 'refs/tags/') || steps.bump.outputs.version != '' }}
+        shell: bash
+        env:
+          KUBECONFIG_B64: ${{ secrets.AI_SPEL_TEST_KUBECONFIG }}
+          AUTO_RELEASE_VERSION: ${{ steps.bump.outputs.version }}
+        run: |
+          set -euo pipefail
+          test -n "$KUBECONFIG_B64"
+          mkdir -p "$RUNNER_TEMP/kube"
+          printf '%s' "$KUBECONFIG_B64" | base64 -d > "$RUNNER_TEMP/kube/config"
+          chmod 600 "$RUNNER_TEMP/kube/config"
+          unset KUBECONFIG_B64
+          export KUBECONFIG="$RUNNER_TEMP/kube/config"
+          version="${AUTO_RELEASE_VERSION:-${GITHUB_REF_NAME#v}}"
+          if ! kubectl -n ai-spel get statefulset ai-spel-nats >/dev/null 2>&1 \
+            && ! kubectl -n argocd get application ai-spel-rule-engine >/dev/null 2>&1; then
+            echo 'NATS is not installed yet. The backend release pipeline bootstraps NATS and this Argo Application.'
+            exit 0
+          fi
+          kubectl -n ai-spel rollout status statefulset/ai-spel-nats --timeout=10m
+          kubectl -n argocd apply -f deploy/argocd/application.yaml
+          kubectl -n argocd patch application ai-spel-rule-engine --type merge -p "{\"spec\":{\"source\":{\"targetRevision\":\"$version\"}}}"
+          deadline=$((SECONDS + 600))
+          while (( SECONDS < deadline )); do
+            sync="$(kubectl -n argocd get application ai-spel-rule-engine -o jsonpath='{.status.sync.status}')"
+            health="$(kubectl -n argocd get application ai-spel-rule-engine -o jsonpath='{.status.health.status}')"
+            if [[ "$sync" == Synced && "$health" == Healthy ]]; then break; fi
+            sleep 5
+          done
+          [[ "$sync" == Synced && "$health" == Healthy ]] || {
+            echo "Argo CD did not reach Synced/Healthy for rule engine $version"
+            kubectl -n argocd get application ai-spel-rule-engine -o jsonpath='{.status.conditions[*].message}'
+            exit 1
+          }
+          kubectl -n ai-spel rollout status deployment/ai-spel-rule-engine --timeout=10m
+          kubectl -n ai-spel get pods -l app.kubernetes.io/instance=ai-spel-rule-engine -o wide
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..04074f5
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,18 @@
+[workspace]
+members = ["crates/rule-engine"]
+resolver = "2"
+
+[workspace.package]
+version = "0.1.0"
+edition = "2024"
+license = "MIT"
+
+[workspace.dependencies]
+async-nats = "0.50"
+axum = { version = "0.8", features = ["macros"] }
+futures-util = "0.3"
+mlua = { version = "0.11.6", features = ["luau", "send", "serde"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+tokio = { version = "1", features = ["macros", "rt-multi-thread", "net", "signal", "time", "sync"] }
+uuid = { version = "1", features = ["serde", "v4"] }
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..820d01f
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,12 @@
+FROM harbor.k3s.k0.nu/ai-spel/game-builder:rust1.89-v2 AS builder
+WORKDIR /src
+COPY Cargo.toml Cargo.lock* ./
+COPY crates ./crates
+RUN cargo build --locked --release -p ai-spel-rule-engine
+
+FROM debian:bookworm-slim
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && rm -rf /var/lib/apt/lists/*
+COPY --from=builder /src/target/release/ai-spel-rule-engine /usr/local/bin/ai-spel-rule-engine
+USER 65532:65532
+EXPOSE 8080
+ENTRYPOINT ["/usr/local/bin/ai-spel-rule-engine"]
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..218ba06
--- /dev/null
+++ b/README.md
@@ -0,0 +1,23 @@
+# ai-spel-rule-engine
+
+The isolated Luau evaluation service for the AI-driven Swedish life simulator.
+It receives bounded, versioned rule invocations over NATS and returns typed
+effect proposals. It has no database or AI-provider integration; the game API
+remains responsible for validating and committing effects.
+
+## Contract
+
+Requests use NATS subject `ai-spel.rules.evaluate.v1` and contract version 1.
+The canonical JSON Schema is `contracts/rule-evaluation-v1.schema.json`.
+Responses echo the correlation ID and have status `evaluated` or `rejected`.
+
+The NATS user may subscribe only to the evaluation subject and publish only to
+reply inboxes. The service receives no credentials other than its own NATS
+identity and has no configured database or AI-provider secrets.
+
+## Local commands
+
+For source development, the Rust commands are `cargo fmt --all -- --check`,
+`cargo test --workspace`, and `cargo clippy --workspace --all-targets -- -D warnings`.
+Production builds, tests, image builds, and executable verification for this
+project are run by Gitea Actions on the existing `large` runner and Kubernetes.
diff --git a/contracts/rule-evaluation-v1.schema.json b/contracts/rule-evaluation-v1.schema.json
new file mode 100644
index 0000000..1f947a2
--- /dev/null
+++ b/contracts/rule-evaluation-v1.schema.json
@@ -0,0 +1,76 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://gitea.k3s.k0.nu/ai-spel/ai-spel-rule-engine/raw/tag/v0.1.0/contracts/rule-evaluation-v1.schema.json",
+  "title": "AI Spel Luau rule evaluation contract v1",
+  "type": "object",
+  "additionalProperties": false,
+  "required": ["contract_version", "correlation_id", "invocation"],
+  "properties": {
+    "contract_version": { "const": 1 },
+    "correlation_id": { "type": "string", "format": "uuid" },
+    "invocation": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["rule_id", "rule_version", "source", "snapshot"],
+      "properties": {
+        "rule_id": { "type": "string", "format": "uuid" },
+        "rule_version": { "type": "integer", "minimum": 1 },
+        "source": { "type": "string", "maxLength": 16384 },
+        "snapshot": {
+          "type": "object",
+          "additionalProperties": false,
+          "required": ["world_id", "version", "world_time", "facts"],
+          "properties": {
+            "world_id": { "type": "string", "format": "uuid" },
+            "version": { "type": "integer" },
+            "world_time": { "type": "integer" },
+            "facts": { "type": "object" }
+          }
+        }
+      }
+    }
+  },
+  "$defs": {
+    "effect": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["kind", "payload"],
+      "properties": {
+        "kind": { "type": "string", "minLength": 1, "maxLength": 64 },
+        "payload": { "type": "object" }
+      }
+    },
+    "response": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["contract_version", "correlation_id", "outcome"],
+      "properties": {
+        "contract_version": { "const": 1 },
+        "correlation_id": { "type": "string", "format": "uuid" },
+        "outcome": {
+          "oneOf": [
+            {
+              "type": "object",
+              "additionalProperties": false,
+              "required": ["status", "effects"],
+              "properties": {
+                "status": { "const": "evaluated" },
+                "effects": { "type": "array", "maxItems": 16, "items": { "$ref": "#/$defs/effect" } }
+              }
+            },
+            {
+              "type": "object",
+              "additionalProperties": false,
+              "required": ["status", "code", "detail"],
+              "properties": {
+                "status": { "const": "rejected" },
+                "code": { "type": "string" },
+                "detail": { "type": "string" }
+              }
+            }
+          ]
+        }
+      }
+    }
+  }
+}
diff --git a/crates/rule-engine/Cargo.toml b/crates/rule-engine/Cargo.toml
new file mode 100644
index 0000000..9510aa3
--- /dev/null
+++ b/crates/rule-engine/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "ai-spel-rule-engine"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+async-nats.workspace = true
+axum.workspace = true
+futures-util.workspace = true
+mlua.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+tokio.workspace = true
+uuid.workspace = true
diff --git a/crates/rule-engine/src/lib.rs b/crates/rule-engine/src/lib.rs
new file mode 100644
index 0000000..5e2eb0a
--- /dev/null
+++ b/crates/rule-engine/src/lib.rs
@@ -0,0 +1,250 @@
+use mlua::{Function, Lua, LuaSerdeExt, Value as LuaValue};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use uuid::Uuid;
+
+pub const CONTRACT_VERSION: u16 = 1;
+pub const EVALUATION_SUBJECT: &str = "ai-spel.rules.evaluate.v1";
+pub const MAX_RULE_BYTES: usize = 16 * 1024;
+pub const MAX_SNAPSHOT_BYTES: usize = 32 * 1024;
+pub const MAX_RESULT_BYTES: usize = 16 * 1024;
+pub const MAX_EFFECTS: usize = 16;
+pub const MAX_MEMORY_BYTES: usize = 2 * 1024 * 1024;
+pub const MAX_INTERRUPTS: usize = 10_000;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct WorldSnapshot {
+    pub world_id: Uuid,
+    pub version: i64,
+    pub world_time: i64,
+    pub facts: Value,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(deny_unknown_fields)]
+pub struct ProposedEffect {
+    pub kind: String,
+    pub payload: Value,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct RuleInvocation {
+    pub rule_id: Uuid,
+    pub rule_version: i32,
+    pub source: String,
+    pub snapshot: WorldSnapshot,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct EvaluationRequest {
+    pub contract_version: u16,
+    pub correlation_id: Uuid,
+    pub invocation: RuleInvocation,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "status", rename_all = "snake_case", deny_unknown_fields)]
+pub enum EvaluationOutcome {
+    Evaluated { effects: Vec<ProposedEffect> },
+    Rejected { code: String, detail: String },
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct EvaluationResponse {
+    pub contract_version: u16,
+    pub correlation_id: Uuid,
+    pub outcome: EvaluationOutcome,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum RuleError {
+    RuleTooLarge,
+    SnapshotTooLarge,
+    ResultTooLarge,
+    TooManyEffects,
+    InvalidEffect,
+    Sandbox(String),
+}
+
+impl RuleError {
+    pub fn code(&self) -> &'static str {
+        match self {
+            Self::RuleTooLarge => "rule_too_large",
+            Self::SnapshotTooLarge => "snapshot_too_large",
+            Self::ResultTooLarge => "result_too_large",
+            Self::TooManyEffects => "too_many_effects",
+            Self::InvalidEffect => "invalid_effect",
+            Self::Sandbox(_) => "sandbox_rejected",
+        }
+    }
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+pub struct LuauRuntime;
+
+impl LuauRuntime {
+    pub fn evaluate(&self, invocation: &RuleInvocation) -> Result<Vec<ProposedEffect>, RuleError> {
+        if invocation.source.len() > MAX_RULE_BYTES {
+            return Err(RuleError::RuleTooLarge);
+        }
+        let snapshot_json = serde_json::to_vec(&invocation.snapshot)
+            .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+        if snapshot_json.len() > MAX_SNAPSHOT_BYTES {
+            return Err(RuleError::SnapshotTooLarge);
+        }
+
+        let lua = Lua::new();
+        lua.set_memory_limit(MAX_MEMORY_BYTES)
+            .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+        lua.sandbox(true)
+            .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+        let interrupt_count = std::sync::Arc::new(std::sync::atomic::AtomicUsize::new(0));
+        lua.set_interrupt({
+            let interrupt_count = interrupt_count.clone();
+            move |_| {
+                let count = interrupt_count.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+                if count >= MAX_INTERRUPTS {
+                    return Err(mlua::Error::RuntimeError(
+                        "rule execution budget exceeded".into(),
+                    ));
+                }
+                Ok(mlua::VmState::Continue)
+            }
+        });
+
+        let result = (|| -> mlua::Result<LuaValue> {
+            let rule: Function = lua.load(&invocation.source).set_name("game-rule").eval()?;
+            let snapshot = lua.to_value(&invocation.snapshot)?;
+            rule.call(snapshot)
+        })()
+        .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+
+        let effects: Vec<ProposedEffect> = lua
+            .from_value(result)
+            .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+        if effects.len() > MAX_EFFECTS {
+            return Err(RuleError::TooManyEffects);
+        }
+        let encoded = serde_json::to_vec(&effects)
+            .map_err(|error| RuleError::Sandbox(error.to_string()))?;
+        if encoded.len() > MAX_RESULT_BYTES {
+            return Err(RuleError::ResultTooLarge);
+        }
+        if effects.iter().any(|effect| {
+            effect.kind.trim().is_empty()
+                || effect.kind.len() > 64
+                || !effect.payload.is_object()
+                || serde_json::to_vec(&effect.payload)
+                    .map(|payload| payload.len() > MAX_RESULT_BYTES)
+                    .unwrap_or(true)
+        }) {
+            return Err(RuleError::InvalidEffect);
+        }
+        Ok(effects)
+    }
+}
+
+pub fn evaluate_request(request: EvaluationRequest) -> EvaluationResponse {
+    let correlation_id = request.correlation_id;
+    let outcome = if request.contract_version != CONTRACT_VERSION {
+        EvaluationOutcome::Rejected {
+            code: "unsupported_contract_version".into(),
+            detail: "The requested rule evaluation contract version is not supported.".into(),
+        }
+    } else {
+        match LuauRuntime.evaluate(&request.invocation) {
+            Ok(effects) => EvaluationOutcome::Evaluated { effects },
+            Err(error) => EvaluationOutcome::Rejected {
+                code: error.code().into(),
+                detail: match error {
+                    RuleError::Sandbox(detail) => detail,
+                    _ => format!("Rule evaluation rejected: {}", error.code()),
+                },
+            },
+        }
+    };
+    EvaluationResponse {
+        contract_version: CONTRACT_VERSION,
+        correlation_id,
+        outcome,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn request(source: &str) -> EvaluationRequest {
+        EvaluationRequest {
+            contract_version: CONTRACT_VERSION,
+            correlation_id: Uuid::nil(),
+            invocation: RuleInvocation {
+                rule_id: Uuid::nil(),
+                rule_version: 1,
+                source: source.into(),
+                snapshot: WorldSnapshot {
+                    world_id: Uuid::nil(),
+                    version: 7,
+                    world_time: 12,
+                    facts: serde_json::json!({"minutes":5}),
+                },
+            },
+        }
+    }
+
+    #[test]
+    fn evaluates_luau_to_typed_proposals() {
+        let result = evaluate_request(request(
+            r#"return function(snapshot)
+                return {{ kind = "advance_time", payload = { minutes = snapshot.facts.minutes } }}
+            end"#,
+        ));
+        let EvaluationOutcome::Evaluated { effects } = result.outcome else {
+            panic!("expected a typed effect proposal");
+        };
+        assert_eq!(effects[0].kind, "advance_time");
+        assert_eq!(effects[0].payload["minutes"], 5);
+    }
+
+    #[test]
+    fn rejects_ambient_io_and_non_effect_results() {
+        let result = evaluate_request(request(
+            "return function() return io.open('/etc/passwd') end",
+        ));
+        assert!(matches!(result.outcome, EvaluationOutcome::Rejected { .. }));
+        let result = evaluate_request(request(
+            "return function() return {{ kind = 'advance_time', payload = 'not an object' }} end",
+        ));
+        assert!(matches!(result.outcome, EvaluationOutcome::Rejected { .. }));
+        let result = evaluate_request(request(
+            "return function() return 'not an effect list' end",
+        ));
+        assert!(matches!(result.outcome, EvaluationOutcome::Rejected { .. }));
+    }
+
+    #[test]
+    fn rejects_execution_budget_exhaustion() {
+        let result = evaluate_request(request("return function() while true do end end"));
+        assert!(matches!(result.outcome, EvaluationOutcome::Rejected { .. }));
+    }
+
+    #[test]
+    fn rejects_wrong_contract_and_oversized_source() {
+        let mut wrong_version = request("return function() return {} end");
+        wrong_version.contract_version = CONTRACT_VERSION + 1;
+        let result = evaluate_request(wrong_version);
+        assert!(matches!(
+            result.outcome,
+            EvaluationOutcome::Rejected { ref code, .. } if code == "unsupported_contract_version"
+        ));
+        let result = evaluate_request(request(&" ".repeat(MAX_RULE_BYTES + 1)));
+        assert!(matches!(
+            result.outcome,
+            EvaluationOutcome::Rejected { ref code, .. } if code == "rule_too_large"
+        ));
+    }
+}
diff --git a/crates/rule-engine/src/main.rs b/crates/rule-engine/src/main.rs
new file mode 100644
index 0000000..a009085
--- /dev/null
+++ b/crates/rule-engine/src/main.rs
@@ -0,0 +1,171 @@
+use ai_spel_rule_engine::{
+    CONTRACT_VERSION, EVALUATION_SUBJECT, EvaluationRequest, EvaluationResponse, evaluate_request,
+};
+use async_nats::{Client, ConnectOptions, Subscriber, Subject};
+use axum::{Router, extract::State, http::StatusCode, routing::get};
+use futures_util::StreamExt;
+use std::{env, sync::Arc, time::Duration};
+use tokio::{task::JoinSet, time};
+
+#[derive(Clone)]
+struct Health {
+    nats_connected: bool,
+}
+
+async fn live() -> StatusCode {
+    StatusCode::NO_CONTENT
+}
+
+async fn ready(State(health): State<Arc<tokio::sync::RwLock<Health>>>) -> StatusCode {
+    if health.read().await.nats_connected {
+        StatusCode::NO_CONTENT
+    } else {
+        StatusCode::SERVICE_UNAVAILABLE
+    }
+}
+
+async fn connect_nats() -> Result<Client, Box<dyn std::error::Error>> {
+    let url = env::var("NATS_URL").unwrap_or_else(|_| "nats://ai-spel-nats:4222".into());
+    let username = env::var("NATS_USERNAME")?;
+    let password = env::var("NATS_PASSWORD")?;
+    Ok(ConnectOptions::new()
+        .user_and_password(username, password)
+        .connect(url)
+        .await?)
+}
+
+async fn smoke_nats() -> Result<(), Box<dyn std::error::Error>> {
+    let client = connect_nats().await?;
+    let correlation_id = uuid::Uuid::new_v4();
+    let request = EvaluationRequest {
+        contract_version: CONTRACT_VERSION,
+        correlation_id,
+        invocation: ai_spel_rule_engine::RuleInvocation {
+            rule_id: uuid::Uuid::nil(),
+            rule_version: 1,
+            source: "return function() return {} end".into(),
+            snapshot: ai_spel_rule_engine::WorldSnapshot {
+                world_id: uuid::Uuid::nil(),
+                version: 0,
+                world_time: 0,
+                facts: serde_json::json!({}),
+            },
+        },
+    };
+    let bytes = serde_json::to_vec(&request)?;
+    let response = time::timeout(
+        Duration::from_secs(5),
+        client.request(EVALUATION_SUBJECT, bytes.into()),
+    )
+    .await??;
+    let response: EvaluationResponse = serde_json::from_slice(&response.payload)?;
+    if response.contract_version != CONTRACT_VERSION || response.correlation_id != correlation_id {
+        return Err("rule service smoke response did not match the request contract".into());
+    }
+    match response.outcome {
+        ai_spel_rule_engine::EvaluationOutcome::Evaluated { effects } if effects.is_empty() => {
+            println!("Rule engine NATS request/reply smoke passed")
+        }
+        _ => return Err("rule service smoke evaluation was rejected or returned effects".into()),
+    }
+    Ok(())
+}
+
+fn response_for_payload(payload: &[u8]) -> Option<Vec<u8>> {
+    let request: EvaluationRequest = match serde_json::from_slice(payload) {
+        Ok(request) => request,
+        Err(_) => return None,
+    };
+    serde_json::to_vec(&evaluate_request(request)).ok()
+}
+
+async fn respond(client: Client, reply: Subject, payload: Vec<u8>) {
+    if let Err(error) = client.publish(reply, payload.into()).await {
+        eprintln!(
+            "{{\"level\":\"error\",\"event\":\"rule.reply_publish_failed\",\"error_category\":\"nats_publish\",\"detail\":{:?}}}",
+            error.to_string()
+        );
+    }
+}
+
+async fn serve_rule_requests(
+    client: Client,
+    mut subscriber: Subscriber,
+    max_concurrency: usize,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let mut tasks = JoinSet::new();
+    loop {
+        tokio::select! {
+            message = subscriber.next() => {
+                let Some(message) = message else { break; };
+                let Some(reply) = message.reply else { continue; };
+                while tasks.len() >= max_concurrency {
+                    let _ = tasks.join_next().await;
+                }
+                let client = client.clone();
+                tasks.spawn(async move {
+                    let payload = tokio::task::spawn_blocking(move || response_for_payload(&message.payload)).await;
+                    if let Ok(Some(payload)) = payload {
+                        respond(client, reply, payload).await;
+                    }
+                });
+            }
+            Some(_) = tasks.join_next(), if !tasks.is_empty() => {}
+        }
+    }
+    while tasks.join_next().await.is_some() {}
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    if env::args().any(|argument| argument == "--smoke") {
+        return smoke_nats().await;
+    }
+    let health = Arc::new(tokio::sync::RwLock::new(Health {
+        nats_connected: false,
+    }));
+    let health_router = Router::new()
+        .route("/health/live", get(live))
+        .route("/health/ready", get(ready))
+        .with_state(health.clone());
+    let health_address = env::var("HEALTH_ADDR").unwrap_or_else(|_| "0.0.0.0:8080".into());
+    let health_listener = tokio::net::TcpListener::bind(health_address).await?;
+    tokio::spawn(async move { let _ = axum::serve(health_listener, health_router).await; });
+
+    let client = loop {
+        match connect_nats().await {
+            Ok(client) => break client,
+            Err(error) => {
+                eprintln!("{{\"level\":\"warn\",\"event\":\"nats.connect_retry\",\"error_category\":\"nats_connect\",\"detail\":{:?}}}", error.to_string());
+                time::sleep(Duration::from_secs(2)).await;
+            }
+        }
+    };
+    let queue_group = env::var("NATS_QUEUE_GROUP").unwrap_or_else(|_| "ai-spel-rule-engine".into());
+    let subscriber = client
+        .queue_subscribe(EVALUATION_SUBJECT, queue_group)
+        .await?;
+    health.write().await.nats_connected = true;
+    {
+        let health = health.clone();
+        let health_client = client.clone();
+        tokio::spawn(async move {
+            loop {
+                let connected = matches!(
+                    time::timeout(Duration::from_secs(2), health_client.flush()).await,
+                    Ok(Ok(()))
+                );
+                health.write().await.nats_connected = connected;
+                time::sleep(Duration::from_secs(5)).await;
+            }
+        });
+    }
+    let concurrency = env::var("RULE_MAX_CONCURRENCY")
+        .ok()
+        .and_then(|value| value.parse::<usize>().ok())
+        .filter(|value| (1..=32).contains(value))
+        .unwrap_or(8);
+    eprintln!("{{\"level\":\"info\",\"event\":\"rule_engine.ready\",\"contract_version\":{},\"max_concurrency\":{}}}", CONTRACT_VERSION, concurrency);
+    serve_rule_requests(client, subscriber, concurrency).await
+}
diff --git a/deploy/argocd/application.yaml b/deploy/argocd/application.yaml
new file mode 100644
index 0000000..f126d3a
--- /dev/null
+++ b/deploy/argocd/application.yaml
@@ -0,0 +1,22 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: ai-spel-rule-engine
+  namespace: argocd
+spec:
+  project: ai-spel
+  source:
+    repoURL: harbor.k3s.k0.nu/ai-spel
+    chart: ai-spel-rule-engine
+    targetRevision: "0.1.0"
+    helm:
+      releaseName: ai-spel-rule-engine
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: ai-spel
+  syncPolicy:
+    automated:
+      prune: false
+      selfHeal: true
+    syncOptions:
+      - CreateNamespace=false
diff --git a/deploy/helm/ai-spel-rule-engine/Chart.yaml b/deploy/helm/ai-spel-rule-engine/Chart.yaml
new file mode 100644
index 0000000..a821047
--- /dev/null
+++ b/deploy/helm/ai-spel-rule-engine/Chart.yaml
@@ -0,0 +1,6 @@
+apiVersion: v2
+name: ai-spel-rule-engine
+description: Isolated, sandboxed Luau proposal evaluator
+type: application
+version: 0.1.0
+appVersion: "0.1.0"
diff --git a/deploy/helm/ai-spel-rule-engine/templates/deployment.yaml b/deploy/helm/ai-spel-rule-engine/templates/deployment.yaml
new file mode 100644
index 0000000..c99eb7d
--- /dev/null
+++ b/deploy/helm/ai-spel-rule-engine/templates/deployment.yaml
@@ -0,0 +1,100 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  replicas: {{ .Values.replicaCount }}
+  minReadySeconds: {{ .Values.deployment.minReadySeconds }}
+  progressDeadlineSeconds: {{ .Values.deployment.progressDeadlineSeconds }}
+  strategy:
+    type: RollingUpdate
+    rollingUpdate:
+      maxUnavailable: {{ .Values.deployment.maxUnavailable }}
+      maxSurge: {{ .Values.deployment.maxSurge }}
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ .Chart.Name }}
+      app.kubernetes.io/instance: {{ .Release.Name }}
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: {{ .Chart.Name }}
+        app.kubernetes.io/instance: {{ .Release.Name }}
+    spec:
+      automountServiceAccountToken: false
+      {{- with .Values.image.pullSecretName }}
+      imagePullSecrets:
+        - name: {{ . | quote }}
+      {{- end }}
+      containers:
+        - name: rule-engine
+          image: "{{ .Values.image.repository }}:{{ .Chart.AppVersion }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          ports:
+            - name: health
+              containerPort: 8080
+          env:
+            - name: HEALTH_ADDR
+              value: "0.0.0.0:8080"
+            - name: NATS_URL
+              value: {{ .Values.nats.url | quote }}
+            - name: NATS_USERNAME
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.nats.secretName }}
+                  key: {{ .Values.nats.usernameKey }}
+            - name: NATS_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.nats.secretName }}
+                  key: {{ .Values.nats.passwordKey }}
+            - name: NATS_QUEUE_GROUP
+              value: {{ .Values.nats.queueGroup | quote }}
+            - name: RULE_MAX_CONCURRENCY
+              value: {{ .Values.runtime.maxConcurrency | quote }}
+          readinessProbe:
+            httpGet:
+              path: /health/ready
+              port: health
+            periodSeconds: 5
+            timeoutSeconds: 2
+            failureThreshold: 3
+          livenessProbe:
+            httpGet:
+              path: /health/live
+              port: health
+            periodSeconds: 10
+            timeoutSeconds: 2
+            failureThreshold: 3
+          resources: {{- toYaml .Values.resources | nindent 12 }}
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            runAsNonRoot: true
+            capabilities:
+              drop: ["ALL"]
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  type: ClusterIP
+  selector:
+    app.kubernetes.io/name: {{ .Chart.Name }}
+    app.kubernetes.io/instance: {{ .Release.Name }}
+  ports:
+    - name: health
+      port: {{ .Values.service.port }}
+      targetPort: health
+---
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  minAvailable: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ .Chart.Name }}
+      app.kubernetes.io/instance: {{ .Release.Name }}
diff --git a/deploy/helm/ai-spel-rule-engine/templates/networkpolicy.yaml b/deploy/helm/ai-spel-rule-engine/templates/networkpolicy.yaml
new file mode 100644
index 0000000..b0ba2bb
--- /dev/null
+++ b/deploy/helm/ai-spel-rule-engine/templates/networkpolicy.yaml
@@ -0,0 +1,30 @@
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  podSelector:
+    matchLabels:
+      app.kubernetes.io/name: {{ .Chart.Name }}
+      app.kubernetes.io/instance: {{ .Release.Name }}
+  policyTypes: [Egress]
+  egress:
+    - to:
+        - podSelector:
+            matchLabels:
+              app.kubernetes.io/instance: ai-spel-nats
+      ports:
+        - protocol: TCP
+          port: 4222
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: kube-system
+          podSelector:
+            matchLabels:
+              k8s-app: kube-dns
+      ports:
+        - protocol: UDP
+          port: 53
+        - protocol: TCP
+          port: 53
diff --git a/deploy/helm/ai-spel-rule-engine/templates/pdb.yaml b/deploy/helm/ai-spel-rule-engine/templates/pdb.yaml
new file mode 100644
index 0000000..50554b1
--- /dev/null
+++ b/deploy/helm/ai-spel-rule-engine/templates/pdb.yaml
@@ -0,0 +1,10 @@
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: {{ .Release.Name }}
+spec:
+  minAvailable: 1
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: {{ .Chart.Name }}
+      app.kubernetes.io/instance: {{ .Release.Name }}
diff --git a/deploy/helm/ai-spel-rule-engine/values.yaml b/deploy/helm/ai-spel-rule-engine/values.yaml
new file mode 100644
index 0000000..9459154
--- /dev/null
+++ b/deploy/helm/ai-spel-rule-engine/values.yaml
@@ -0,0 +1,27 @@
+image:
+  repository: harbor.k3s.k0.nu/ai-spel/rule-engine
+  pullPolicy: Always
+  pullSecretName: harbor-pull
+replicaCount: 2
+deployment:
+  maxUnavailable: 0
+  maxSurge: 1
+  minReadySeconds: 5
+  progressDeadlineSeconds: 600
+service:
+  port: 8080
+nats:
+  url: nats://ai-spel-nats:4222
+  secretName: ai-spel-rule-engine-nats
+  usernameKey: username
+  passwordKey: password
+  queueGroup: ai-spel-rule-engine
+runtime:
+  maxConcurrency: 8
+resources:
+  requests:
+    cpu: 100m
+    memory: 128Mi
+  limits:
+    cpu: 1
+    memory: 384Mi
diff --git a/docs/adr/0001-isolated-luau-runtime.md b/docs/adr/0001-isolated-luau-runtime.md
new file mode 100644
index 0000000..f011549
--- /dev/null
+++ b/docs/adr/0001-isolated-luau-runtime.md
@@ -0,0 +1,15 @@
+# ADR 0001: Isolated Luau runtime
+
+## Status
+
+Accepted; deployment verification is pending the first `large` pipeline release.
+
+## Decision
+
+This repository owns the Luau sandbox and the v1 request/reply schema. It accepts only a versioned rule source and a bounded, read-only snapshot, then returns typed effect proposals. It has no database or AI provider dependency. The service connects to the private `ai-spel.rules.evaluate.v1` NATS subject in a queue group so multiple replicas can share direct-scene evaluations.
+
+The service cannot make a world change. The API validates every returned effect and is the only writer of canonical state. Synchronous evaluations use Core NATS; durable asynchronous work is out of scope until an outbox/inbox and idempotent JetStream consumer exist.
+
+## Verification required
+
+The release workflow runs Rust checks and Helm checks on the existing `large` runner, publishes version-matched image/chart/manifest artifacts, and verifies the Argo rollout in Kubernetes. Live worker-loss and request/reply checks remain required before calling this service production-verified.
diff --git a/scripts/bump-release-version.py b/scripts/bump-release-version.py
new file mode 100644
index 0000000..032f914
--- /dev/null
+++ b/scripts/bump-release-version.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+"""Bump all rule-engine release metadata from the workspace version."""
+from pathlib import Path
+import re
+
+cargo_path = Path("Cargo.toml")
+cargo = cargo_path.read_text()
+match = re.search(r'(?ms)(^\[workspace\.package\]\s+.*?^version\s*=\s*")(\d+)\.(\d+)\.(\d+)(")', cargo)
+if not match:
+    raise SystemExit("Missing [workspace.package].version")
+major, minor, patch = map(int, match.group(2, 3, 4))
+version = f"{major}.{minor}.{patch + 1}"
+cargo_path.write_text(cargo[:match.start(2)] + version + cargo[match.end(4):])
+
+for path, pattern in (
+    (Path("deploy/helm/ai-spel-rule-engine/Chart.yaml"), r'(?m)^version:\s*\d+\.\d+\.\d+\s*$'),
+    (Path("deploy/helm/ai-spel-rule-engine/Chart.yaml"), r'(?m)^appVersion:\s*"\d+\.\d+\.\d+"\s*$'),
+    (Path("deploy/argocd/application.yaml"), r'(?m)^\s+targetRevision:\s*"\d+\.\d+\.\d+"\s*$'),
+):
+    contents = path.read_text()
+    if not re.search(pattern, contents):
+        raise SystemExit(f"Missing version field in {path}")
+    replacement = f'version: {version}' if pattern.startswith(r'(?m)^version') else (
+        f'appVersion: "{version}"' if pattern.startswith(r'(?m)^appVersion') else f'    targetRevision: "{version}"'
+    )
+    path.write_text(re.sub(pattern, replacement, contents, count=1))
+print(version)