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plainpages/src/plugin.ts

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// The plugin contract (todo §2) — the product's main API surface: the machine-readable types +
// pure rules; `docs/plugin-contract.md` is the prose reference, discovery/router wire it to FS+HTTP.
// Powerful, predictable, fails loud at boot/discovery rather than sandboxing at runtime.
//
// A plugin's identity is its folder under plugins/: folder name = `id` (isValidPluginId), mount =
// `/<id>`. Neither is in the manifest — the host derives them, so they can't drift or be claimed twice.
import type { RequestContext } from "./context.ts";
import type { NavNode } from "./nav.ts";
// Host contract version (semver). Bump major on a breaking manifest/handler change, minor on an
// additive one. A plugin pins the version it targets via `apiVersion`; the host applies
// provider/consumer semver semantics in checkApiVersion (refuse/warn on mismatch).
export const HOST_API_VERSION = "1.0.0";
export type HttpMethod = "DELETE" | "GET" | "HEAD" | "PATCH" | "POST" | "PUT";
// A handler's return value; the host turns it into the HTTP response. Returning void is the
// escape hatch — the handler wrote to `ctx.res` itself (streaming, custom headers, etc.).
export type RouteResult =
| { headers?: Record<string, string>; html: string; status?: number }
| { headers?: Record<string, string>; json: unknown; status?: number } // for opt-in JS enhancement
| { data?: Record<string, unknown>; headers?: Record<string, string>; status?: number; view: string }
| { redirect: string; status?: number };
export type RouteHandler = (ctx: RequestContext) => Promise<RouteResult | void> | RouteResult | void;
export interface Route {
handler: RouteHandler;
method: HttpMethod;
path: string; // relative to the plugin's mount path `/<id>`; ":name" segments → ctx.params.name
permission?: string; // coarse gate (a role token); checked before the handler runs
}
// A permission token this plugin introduces — declared for docs/seeding. Tokens are a shared
// global namespace (so an operator grants them in Keto); namespace as `<id>:<action>`.
export interface PermissionDecl {
description?: string;
token: string;
}
// Optional hooks on system actions. Crash-isolation is a non-goal — a throwing hook fails loud.
export interface PluginHooks {
onBoot?: () => Promise<void> | void; // after discovery, before the server listens
onRequest?: (ctx: RequestContext) => Promise<RouteResult | void> | RouteResult | void; // may short-circuit
onResponse?: (ctx: RequestContext, result: RouteResult | null) => Promise<void> | void;
}
// The authored manifest — a plugin's `plugin.ts` default-exports this. No `id`/mount path: the
// host derives them from the folder name at discovery (see Plugin).
export interface PluginManifest {
apiVersion: string; // semver of the host contract this targets — write a literal, NOT HOST_API_VERSION (see docs)
// Take over the dashboard "/" — the post-login landing page (§10). A handler like any route's,
// gated by the host to a signed-in session (anonymous → /login); render its own view via ctx.chrome.
// At most one plugin may declare it (findConflicts → error, never last-write-wins).
home?: RouteHandler;
hooks?: PluginHooks;
nav?: NavNode[]; // fragment merged into the menu (composeNav); node `icon` is a Lucide sprite id (src/icons.ts), node ids must be globally unique
permissions?: PermissionDecl[];
routes?: Route[];
}
// A discovered plugin: the manifest plus the `id` the host read from the folder name. Mounted
// at `/<id>`, with views/static namespaced under the id.
export interface Plugin extends PluginManifest {
id: string;
}
// Identity helper: types the manifest, returns it unchanged. Validation happens at discovery
// (§2), so a plugin may equally be a plain typed object. Mirrors Vite's `defineConfig`.
export function definePlugin(manifest: PluginManifest): PluginManifest {
return manifest;
}
// A plugin id (its folder name) — lowercase az, digits, and dashes, dashes allowed anywhere.
// Rejects uppercase, underscores, dots, slashes, spaces: the id forms the mount path `/<id>`,
// the view/static namespace, and the central-override target, so it must stay URL/path-safe.
const PLUGIN_ID = /^[a-z0-9-]+$/;
export function isValidPluginId(id: string): boolean {
return PLUGIN_ID.test(id);
}
// Ids the host reserves for its own first-party mount segments (the auth flows, /auth/complete,
// /logout, the /admin screens, the /oauth2 provider routes, the dashboard's /public/ static).
// Plugin routes resolve before these, so a folder named one of them would silently shadow a
// built-in route — discovery refuses it, loud like any conflict.
export const RESERVED_PLUGIN_IDS: ReadonlySet<string> = new Set([
"admin", "auth", "login", "logout", "oauth2", "public", "recovery", "registration", "settings", "verification",
]);
export interface Semver {
major: number;
minor: number;
patch: number;
}
// The official semver.org 2.0.0 core regex (major.minor.patch, optional prerelease/build) — a
// standardized parse with no dependency. We compare only major/minor for compatibility, so the
// prerelease/build groups are matched (to accept valid input) but otherwise ignored.
const SEMVER =
/^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*)?(?:\+[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*)?$/;
// Parse a strict semver string → {major, minor, patch}, or null. Rejects ranges/prefixes
// (`^1.2.3`, `v1`), leading zeros, whitespace and missing parts — fail loud over coerce.
export function parseSemver(version: unknown): Semver | null {
if (typeof version !== "string") return null;
const m = SEMVER.exec(version);
if (!m) return null;
return { major: Number(m[1]), minor: Number(m[2]), patch: Number(m[3]) };
}
export interface VersionCheck {
level: "ok" | "refuse" | "warn";
message: string;
}
// Provider/consumer semver check (full table in docs/plugin-contract.md): same major+minor → ok,
// plugin minor < host → warn, else (newer minor, major mismatch, malformed) → refuse. Patch is
// ignored. Discovery maps refuse→throw, warn→log.
export function checkApiVersion(pluginVersion: unknown, hostVersion: string = HOST_API_VERSION): VersionCheck {
const plugin = parseSemver(pluginVersion);
const host = parseSemver(hostVersion);
if (!host) throw new Error(`hostVersion is not a semver: ${JSON.stringify(hostVersion)}`); // invariant, not user input
if (!plugin) {
return { level: "refuse", message: `apiVersion must be a semver string (e.g. "${hostVersion}"); got ${JSON.stringify(pluginVersion)}` };
}
if (plugin.major !== host.major) {
return { level: "refuse", message: `plugin targets apiVersion ${pluginVersion}; host is ${hostVersion} — incompatible major` };
}
if (plugin.minor > host.minor) {
return { level: "refuse", message: `plugin targets apiVersion ${pluginVersion} but host is ${hostVersion}; upgrade the host` };
}
if (plugin.minor < host.minor) {
return { level: "warn", message: `plugin targets apiVersion ${pluginVersion}; host is ${hostVersion} — newer features available` };
}
return { level: "ok", message: `apiVersion ${pluginVersion}` };
}
export interface PluginConflict {
kind: "home" | "id" | "nav-id" | "permission" | "route";
level: "error" | "warn";
message: string;
plugins: string[]; // unique ids involved
}
// The conflict rules: defined, loud resolution — never last-write-wins. Pure over the discovered
// plugins; discovery throws on any "error" and logs every "warn". Mount-path (`/<id>`) uniqueness
// is structural — it follows from the id check, so it needs no rule of its own. Shared permission
// tokens are the one intentional overlap, so they warn rather than error.
export function findConflicts(plugins: Plugin[]): PluginConflict[] {
const out: PluginConflict[] = [];
const idCounts = new Map<string, number>();
for (const plugin of plugins) idCounts.set(plugin.id, (idCounts.get(plugin.id) ?? 0) + 1);
for (const [id, n] of idCounts) {
if (n > 1) out.push({ kind: "id", level: "error", message: `${n} plugins share id "${id}"; ids must be globally unique`, plugins: [id] });
}
// The dashboard "/" is a single slot (§10): two plugins claiming `home` is a loud error, not a race.
const homeOwners = plugins.filter((plugin) => plugin.home).map((plugin) => plugin.id);
if (homeOwners.length > 1) out.push({ kind: "home", level: "error", message: `${homeOwners.length} plugins claim the dashboard "home" (${homeOwners.join(", ")}); only one may`, plugins: uniq(homeOwners) });
collect(plugins, (plugin, push) => {
for (const route of plugin.routes ?? []) push(`${route.method} ${fullPath(plugin.id, route.path)}`);
}).forEach((owners, key) => {
if (owners.length > 1) out.push({ kind: "route", level: "error", message: `${owners.length} routes resolve to "${key}"`, plugins: uniq(owners) });
});
collect(plugins, (plugin, push) => collectNavIds(plugin.nav, push)).forEach((owners, id) => {
if (owners.length > 1) out.push({ kind: "nav-id", level: "error", message: `nav id "${id}" used ${owners.length}×; override targets ids, so they must be unique`, plugins: uniq(owners) });
});
collect(plugins, (plugin, push) => {
for (const decl of plugin.permissions ?? []) push(decl.token);
}).forEach((owners, token) => {
if (owners.length > 1) out.push({ kind: "permission", level: "warn", message: `permission "${token}" declared by ${uniq(owners).length} plugins; namespace as "<id>:<action>" unless shared on purpose`, plugins: uniq(owners) });
});
return out;
}
// Map each emitted key → the plugin ids that emitted it (repeats kept, so within-plugin dups count).
function collect(plugins: Plugin[], emit: (plugin: Plugin, push: (key: string) => void) => void): Map<string, string[]> {
const owners = new Map<string, string[]>();
for (const plugin of plugins) emit(plugin, (key) => owners.set(key, [...(owners.get(key) ?? []), plugin.id]));
return owners;
}
function collectNavIds(nodes: NavNode[] | undefined, push: (id: string) => void): void {
for (const node of nodes ?? []) {
if (node.id != null) push(node.id);
collectNavIds(node.children, push);
}
}
// A route's full path = the plugin's mount path `/<id>` + the route path. The single source of
// truth for both conflict detection (here) and the §2 router, so they can't disagree.
export function fullPath(id: string, path: string): string {
return `/${id}${path.startsWith("/") ? path : `/${path}`}`;
}
function uniq(xs: string[]): string[] {
return [...new Set(xs)];
}