feat(modules): add package field + Modules bundle + addressed evaluate

ast.zig:
- Module gains optional package field (default "").
- New Modules struct wrapping a slice of Module.
- New buildModulesBundle handles {"type":"modules","modules":[...]}
  plus the legacy single-module / bare-expression forms (wrapped as
  a 1-element bundle with package="" for backwards compat).

eval.zig:
- New evaluateAddressed(arena, input, ast, target_pkg, target_rule)
  parses the AST as a bundle and dispatches to package.rule.
- Existing evaluate() delegates to evaluateAddressed with
  ("", "allow"), so all existing call sites are untouched.
- New evalBundle OR-combines evalModule across every module whose
  package matches; missing package -> deny by default.

Tests:
- src/eval.zig: 4 unit tests (cross-package addressing, missing
  package, backwards compat, OR within a package).
- test/run.mjs and test/run_wasmtime.py: 4 cases each verifying
  the wire format works through the wasm boundary.

Release build grows from 50K to 54K. ci.yml gains the test-unit job
in line with the other implementation branches.

Author: kanywst

.github/workflows/ci.yml

@@ -41,6 +41,19 @@ jobs:
           path: zig-out/bin/zopa.wasm
           if-no-files-found: error
 
+  test-unit:
+    name: test (unit)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: mlugg/setup-zig@d1434d08867e3ee9daa34448df10607b98908d29 # v2.2.1
+        with:
+          version: 0.16.0
+
+      - name: zig build test-unit
+        run: zig build test-unit
+
   test-node:
     name: test (node)
     runs-on: ubuntu-latest

src/ast.zig

@@ -68,15 +68,30 @@ pub const Rule = struct {
 };
 
 /// A compiled policy module. Rules with the same name OR-combine.
+/// `package` is optional ("" means the implicit single-module case);
+/// see `Modules` for how multi-package bundles are addressed.
 pub const Module = struct {
     rules: []const Rule,
+    package: []const u8 = "",
+};
+
+/// A bundle of modules. Allows the proxy-wasm shim to load multiple
+/// independently authored policies into a single VM and dispatch
+/// per request to a specific `(package, rule)` target.
+///
+/// Bare `{"type":"module",...}` and bare expressions still work via
+/// `buildModule`; `buildModulesBundle` wraps either form into a
+/// single-element bundle with `package=""` for backwards compat.
+pub const Modules = struct {
+    modules: []const Module,
 };
 
 // Builders. Consume a `json.Value`, return arena-allocated nodes.
 
 /// Build a `Module`. Accepts either the canonical
 /// `{"type":"module","rules":[...]}` shape or a bare expression,
-/// which is wrapped into a synthetic `allow` rule.
+/// which is wrapped into a synthetic `allow` rule. `package` is
+/// read from the canonical shape if present.
 pub fn buildModule(allocator: std.mem.Allocator, node: Value) !Module {
     if (node != .object) return error.InvalidAst;
 
@@ -89,7 +104,11 @@ pub fn buildModule(allocator: std.mem.Allocator, node: Value) !Module {
         for (rules_v.array, 0..) |item, i| {
             rules[i] = try buildRule(allocator, item);
         }
-        return .{ .rules = rules };
+        const pkg: []const u8 = if (json.lookupMember(node.object, "package")) |p_v| pkg_blk: {
+            if (p_v != .string) return error.InvalidPackage;
+            break :pkg_blk p_v.string;
+        } else "";
+        return .{ .rules = rules, .package = pkg };
     }
 
     // Legacy: bare expression -> single synthetic `allow` rule.
@@ -103,7 +122,32 @@ pub fn buildModule(allocator: std.mem.Allocator, node: Value) !Module {
         .value = null,
         .is_default = false,
     };
-    return .{ .rules = rules };
+    return .{ .rules = rules, .package = "" };
+}
+
+/// Build a `Modules` bundle. Accepts:
+///   `{"type":"modules","modules":[<module>, ...]}` -> multi-package
+///   `{"type":"module", ...}`                       -> single module
+///   bare expression                                -> synthetic allow
+pub fn buildModulesBundle(allocator: std.mem.Allocator, node: Value) !Modules {
+    if (node == .object) {
+        if (json.lookupMember(node.object, "type")) |t_v| {
+            if (t_v == .string and std.mem.eql(u8, t_v.string, "modules")) {
+                const list_v = try requireField(node.object, "modules");
+                if (list_v != .array) return error.InvalidModules;
+                const mods = try allocator.alloc(Module, list_v.array.len);
+                for (list_v.array, 0..) |item, i| {
+                    mods[i] = try buildModule(allocator, item);
+                }
+                return .{ .modules = mods };
+            }
+        }
+    }
+    // Single-module / bare-expression form: wrap into a 1-element bundle.
+    const single = try buildModule(allocator, node);
+    const mods = try allocator.alloc(Module, 1);
+    mods[0] = single;
+    return .{ .modules = mods };
 }
 
 fn buildRule(allocator: std.mem.Allocator, node: Value) !Rule {

src/eval.zig

@@ -38,18 +38,50 @@ const Scope = struct {
 
 /// Run a single evaluation. `arena` must already be initialised; this
 /// function neither inits nor resets it -- that is the caller's job.
+///
+/// Targets the default package ("") and the default rule ("allow").
+/// Use `evaluateAddressed` to dispatch into a specific `package.rule`
+/// pair within a `{"type":"modules", ...}` bundle.
 pub fn evaluate(
     arena: *std.heap.ArenaAllocator,
     input_json: []const u8,
     ast_json: []const u8,
+) !bool {
+    return evaluateAddressed(arena, input_json, ast_json, "", default_target_rule);
+}
+
+/// Run a single evaluation against `target_package.target_rule`. The
+/// AST source can be either a single module or a `Modules` bundle;
+/// the legacy single-module form is treated as `package = ""`.
+pub fn evaluateAddressed(
+    arena: *std.heap.ArenaAllocator,
+    input_json: []const u8,
+    ast_json: []const u8,
+    target_package: []const u8,
+    target_rule: []const u8,
 ) !bool {
     const allocator = arena.allocator();
 
     const input_value = try json.parse(allocator, input_json);
     const ast_value = try json.parse(allocator, ast_json);
-    const module = try ast.buildModule(allocator, ast_value);
+    const bundle = try ast.buildModulesBundle(allocator, ast_value);
 
-    return evalModule(module, default_target_rule, input_value);
+    return evalBundle(bundle, target_package, target_rule, input_value);
+}
+
+/// OR-combine evalModule across every module whose package matches.
+/// Empty match set returns `false` (deny by default).
+fn evalBundle(
+    bundle: ast.Modules,
+    target_package: []const u8,
+    target_rule: []const u8,
+    input: json.Value,
+) !bool {
+    for (bundle.modules) |module| {
+        if (!std.mem.eql(u8, module.package, target_package)) continue;
+        if (try evalModule(module, target_rule, input)) return true;
+    }
+    return false;
 }
 
 /// Walk every rule named `target`. A `default` rule's value becomes
@@ -317,6 +349,72 @@ test "evaluate: default rule when no other rule matches" {
     try testing.expect(try run("{\"role\":\"admin\"}", policy));
 }
 
+fn runAddressed(input: []const u8, ast_src: []const u8, pkg: []const u8, rule: []const u8) !bool {
+    var arena = std.heap.ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    return evaluateAddressed(&arena, input, ast_src, pkg, rule);
+}
+
+test "modules bundle: address authz.allow vs audit.allow" {
+    const policy =
+        "{\"type\":\"modules\",\"modules\":[" ++
+        "{\"type\":\"module\",\"package\":\"authz\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"eq\"," ++
+        "\"left\":{\"type\":\"ref\",\"path\":[\"input\",\"role\"]}," ++
+        "\"right\":{\"type\":\"value\",\"value\":\"admin\"}}]}]}," ++
+        "{\"type\":\"module\",\"package\":\"audit\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"value\",\"value\":true}]}]}" ++
+        "]}";
+
+    // authz.allow fires only on admin.
+    try testing.expect(try runAddressed("{\"role\":\"admin\"}", policy, "authz", "allow"));
+    try testing.expect(!(try runAddressed("{\"role\":\"guest\"}", policy, "authz", "allow")));
+
+    // audit.allow always fires regardless of role.
+    try testing.expect(try runAddressed("{\"role\":\"guest\"}", policy, "audit", "allow"));
+}
+
+test "modules bundle: missing package -> deny" {
+    const policy =
+        "{\"type\":\"modules\",\"modules\":[" ++
+        "{\"type\":\"module\",\"package\":\"authz\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"value\",\"value\":true}]}]}" ++
+        "]}";
+    try testing.expect(!(try runAddressed("{}", policy, "missing", "allow")));
+}
+
+test "modules bundle: bare module wraps as package='' (backwards compat)" {
+    const policy =
+        "{\"type\":\"module\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"value\",\"value\":true}]}]}";
+    try testing.expect(try runAddressed("{}", policy, "", "allow"));
+    // Same module via the default `evaluate` entry must still allow.
+    try testing.expect(try run("{}", policy));
+}
+
+test "modules bundle: OR across two modules in same package" {
+    const policy =
+        "{\"type\":\"modules\",\"modules\":[" ++
+        "{\"type\":\"module\",\"package\":\"authz\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"eq\"," ++
+        "\"left\":{\"type\":\"ref\",\"path\":[\"input\",\"role\"]}," ++
+        "\"right\":{\"type\":\"value\",\"value\":\"admin\"}}]}]}," ++
+        "{\"type\":\"module\",\"package\":\"authz\",\"rules\":[" ++
+        "{\"type\":\"rule\",\"name\":\"allow\",\"body\":[" ++
+        "{\"type\":\"eq\"," ++
+        "\"left\":{\"type\":\"ref\",\"path\":[\"input\",\"role\"]}," ++
+        "\"right\":{\"type\":\"value\",\"value\":\"editor\"}}]}]}" ++
+        "]}";
+    try testing.expect(try runAddressed("{\"role\":\"admin\"}", policy, "authz", "allow"));
+    try testing.expect(try runAddressed("{\"role\":\"editor\"}", policy, "authz", "allow"));
+    try testing.expect(!(try runAddressed("{\"role\":\"guest\"}", policy, "authz", "allow")));
+}
+
 test "evaluate: every+some over arrays" {
     const policy =
         "{\"type\":\"every\",\"var\":\"req\"," ++

test/run.mjs

@@ -354,6 +354,69 @@ check(
   0,
 );
 
+// ---------------------------------------------------------------------------
+// 8. modules bundle: package addressing
+//
+// The default `evaluate` ABI targets package="" + rule="allow", so a
+// bare module wrapped at the top level keeps working. A modules
+// bundle with package="" still answers via the default entry point.
+// (Cross-package addressing is exercised by zig build test-unit.)
+// ---------------------------------------------------------------------------
+const wrappedModule = {
+  type: 'modules',
+  modules: [
+    {
+      type: 'module',
+      package: '',
+      rules: [
+        {
+          type: 'rule',
+          name: 'allow',
+          body: [
+            { type: 'eq', left: refRole, right: { type: 'value', value: 'admin' } },
+          ],
+        },
+      ],
+    },
+  ],
+};
+check('modules bundle: empty package -> allow when admin',  decide({ user: { role: 'admin' } },  wrappedModule), 1);
+check('modules bundle: empty package -> deny when guest',   decide({ user: { role: 'guest' } },  wrappedModule), 0);
+
+// Bundle with two packages: the default ABI only sees the empty-package
+// module. The "audit" module is invisible from the default entry.
+const twoPackages = {
+  type: 'modules',
+  modules: [
+    {
+      type: 'module',
+      package: '',
+      rules: [
+        {
+          type: 'rule',
+          name: 'allow',
+          body: [
+            { type: 'eq', left: refRole, right: { type: 'value', value: 'admin' } },
+          ],
+        },
+      ],
+    },
+    {
+      type: 'module',
+      package: 'audit',
+      rules: [
+        {
+          type: 'rule',
+          name: 'allow',
+          body: [{ type: 'value', value: true }],
+        },
+      ],
+    },
+  ],
+};
+check('modules bundle: default entry picks empty package', decide({ user: { role: 'admin' } }, twoPackages), 1);
+check('modules bundle: audit module invisible from default entry', decide({ user: { role: 'guest' } }, twoPackages), 0);
+
 if (failed > 0) {
   console.error(`\n${failed} test(s) failed`);
   exit(1);

test/run_wasmtime.py

@@ -238,6 +238,52 @@ def check(name: str, got, expected):
     0,
 )
 
+# ---------------------------------------------------------------------------
+# 8. modules bundle: package addressing (default entry point only)
+# ---------------------------------------------------------------------------
+wrapped_module = {
+    "type": "modules",
+    "modules": [
+        {
+            "type": "module",
+            "package": "",
+            "rules": [
+                {
+                    "type": "rule",
+                    "name": "allow",
+                    "body": [{"type": "eq", "left": ref_role, "right": {"type": "value", "value": "admin"}}],
+                }
+            ],
+        }
+    ],
+}
+check("modules bundle: empty package -> allow when admin", decide({"user": {"role": "admin"}}, wrapped_module), 1)
+check("modules bundle: empty package -> deny when guest", decide({"user": {"role": "guest"}}, wrapped_module), 0)
+
+two_packages = {
+    "type": "modules",
+    "modules": [
+        {
+            "type": "module",
+            "package": "",
+            "rules": [
+                {
+                    "type": "rule",
+                    "name": "allow",
+                    "body": [{"type": "eq", "left": ref_role, "right": {"type": "value", "value": "admin"}}],
+                }
+            ],
+        },
+        {
+            "type": "module",
+            "package": "audit",
+            "rules": [{"type": "rule", "name": "allow", "body": [{"type": "value", "value": True}]}],
+        },
+    ],
+}
+check("modules bundle: default entry picks empty package", decide({"user": {"role": "admin"}}, two_packages), 1)
+check("modules bundle: audit module invisible from default entry", decide({"user": {"role": "guest"}}, two_packages), 0)
+
 if failed:
     print(f"\n{failed} test(s) failed", file=sys.stderr)
     sys.exit(1)