feat: add core authorization foundation

packages/contracts/src/authorization.ts

@@ -0,0 +1,119 @@
+import { z } from "zod";
+import type { EkklesiaUserId } from "./identity.js";
+import { parseEkklesiaUserId } from "./identity.js";
+
+/**
+ * Opaque at the type level via Zod's nominal `.brand()`, exactly like `EkklesiaUserId` and
+ * `PermissionId`: a plain `string` is not assignable to `GrantId` without passing through
+ * `parseGrantId`/`safeParseGrantId`. Ekklesia does not assume any particular format; Core's
+ * Postgres-backed store happens to generate a UUID, but callers must treat the value as opaque.
+ */
+export const grantIdSchema = z.string().trim().min(1).max(128).brand<"GrantId">();
+
+export type GrantId = z.infer<typeof grantIdSchema>;
+
+export function parseGrantId(input: unknown): GrantId {
+  return grantIdSchema.parse(input);
+}
+
+export function safeParseGrantId(input: unknown): z.ZodSafeParseResult<GrantId> {
+  return grantIdSchema.safeParse(input);
+}
+
+/**
+ * A generic, Core-opaque resource scope narrowing a grant or an authorization check to one
+ * resource (for example a specific calendar event or media item). Core never interprets the
+ * value beyond exact string equality — the owning module defines what a scope string means, if
+ * anything. Not branded: unlike a permission or a grant, a scope carries no identity of its own
+ * within Core; it is simply an opaque comparison key.
+ */
+export const authorizationScopeSchema = z.string().trim().min(1).max(256);
+
+export type AuthorizationScope = z.infer<typeof authorizationScopeSchema>;
+
+export function parseAuthorizationScope(input: unknown): AuthorizationScope {
+  return authorizationScopeSchema.parse(input);
+}
+
+export function safeParseAuthorizationScope(
+  input: unknown,
+): z.ZodSafeParseResult<AuthorizationScope> {
+  return authorizationScopeSchema.safeParse(input);
+}
+
+/**
+ * Every permission declaration has exactly one baseline. `public` allows any principal, anonymous
+ * or authenticated. `authenticated` requires a valid authenticated principal and nothing more.
+ * `restricted` requires an active matching grant or platform-owner authority — baseline alone
+ * never satisfies it.
+ */
+export const permissionBaselineSchema = z.enum(["public", "authenticated", "restricted"]);
+
+export type PermissionBaseline = z.infer<typeof permissionBaselineSchema>;
+
+/**
+ * Distinguishes a grant an operator/system created directly (`explicit`) from one a module
+ * created as a side effect of its own business operation, attributed to some source the module
+ * understands (`relationship`) — for example adding a person to a volunteer roster. Core never
+ * interprets which relationship produced the grant; it only records the distinction and an
+ * opaque source reference for audit purposes.
+ */
+export const grantSourceKindSchema = z.enum(["explicit", "relationship"]);
+
+export type GrantSourceKind = z.infer<typeof grantSourceKindSchema>;
+
+/** A Core-opaque reference to whatever produced a `relationship` grant (or, optionally, extra
+ * context for an `explicit` one) — for example a module-defined identifier. Never interpreted by
+ * Core, never a foreign key into another module's tables. */
+export const grantSourceRefSchema = z.string().trim().min(1).max(256);
+
+export type GrantSourceRef = z.infer<typeof grantSourceRefSchema>;
+
+const authorizationActorTypeSchema = z.enum(["user", "system"]);
+
+export type AuthorizationActorType = z.infer<typeof authorizationActorTypeSchema>;
+
+export interface AuthorizationUserActor {
+  readonly type: "user";
+  readonly userId: EkklesiaUserId;
+}
+
+export interface AuthorizationSystemActor {
+  readonly type: "system";
+}
+
+/**
+ * Who performed a security-relevant authorization mutation (a grant or platform-owner change).
+ * Mirrors `EkklesiaPrincipal`'s discriminated-union style. `system` covers Core-internal or
+ * automated actions with no specific human actor (for example a future bootstrap command run by
+ * an operator with no prior Ekklesia identity); it never means "unauthenticated" or "anonymous
+ * caller" — every mutating call site chooses this deliberately.
+ */
+export type AuthorizationActor = AuthorizationUserActor | AuthorizationSystemActor;
+
+export const SYSTEM_ACTOR: AuthorizationSystemActor = Object.freeze({ type: "system" });
+
+export function createUserActor(userId: unknown): AuthorizationUserActor {
+  return Object.freeze({ type: "user", userId: parseEkklesiaUserId(userId) });
+}
+
+export function isUserActor(actor: AuthorizationActor): actor is AuthorizationUserActor {
+  return actor.type === "user";
+}
+
+/**
+ * The only public result of an authorization check. Deliberately minimal and frozen: it never
+ * carries a reason, a matched grant, a permission echo, or any other detail a caller could use to
+ * infer another user's grants or Core's internal evaluation path. `AUTHORIZATION_ALLOWED` and
+ * `AUTHORIZATION_DENIED` are the only two values ever produced.
+ */
+export interface AuthorizationDecision {
+  readonly allowed: boolean;
+}
+
+export const AUTHORIZATION_ALLOWED: AuthorizationDecision = Object.freeze({ allowed: true });
+export const AUTHORIZATION_DENIED: AuthorizationDecision = Object.freeze({ allowed: false });
+
+export function isAuthorizationAllowed(decision: AuthorizationDecision): boolean {
+  return decision.allowed;
+}