Organize src/ into concern folders (http, auth, admin, plugin-host, ui); co-locate tests, move plugin-api barrel into plugin-host, sync docs + AGENTS layout

plugins/scheduling/plugin.ts

@@ -2,7 +2,7 @@
 // data, a CSRF-guarded form that forwards a write upstream, and permission-gated nav. Copy this
 // folder, rename it, point it at your own backend. Full contract: docs/plugin-contract.md.
 
-import { definePlugin } from "../../src/plugin-api.ts";
+import { definePlugin } from "../../src/plugin-host/plugin-api.ts";
 import { assertHttpUrl, createShift, createUpstream, listShifts, newShiftForm, overview, READ, SCHEDULING_PATH, SHIFTS_PATH, WRITE } from "./shifts.ts";
 
 // The upstream this plugin reads/writes — a stand-in for your real backend (the plugin is

plugins/scheduling/shifts.test.ts

@@ -4,7 +4,7 @@ import { Readable } from "node:stream";
 import test from "node:test";
 // Import only from the plugin-api barrel — the same contract boundary shifts.ts uses (the host may
 // refactor any deeper src/* freely behind it); the test models the dev/test story the contract preaches.
-import { GuardError, Log, type PageChrome, type RequestContext, type RouteResult } from "../../src/plugin-api.ts";
+import { GuardError, Log, type PageChrome, type RequestContext, type RouteResult } from "../../src/plugin-host/plugin-api.ts";
 import {
   assertHttpUrl, buildFormModel, createShift, createUpstream, listShifts, newShiftForm, overview, readInput,
   SHIFTS_PATH, type Shift, type ShiftInput, type ShiftsUpstream, UpstreamError, validate,

plugins/scheduling/shifts.ts

@@ -6,7 +6,7 @@
 // pure functions against a mock upstream with no network (docs/plugin-contract.md → dev/test story).
 
 // One import from the host's plugin-api barrel — the stable author surface (see docs/plugin-contract.md).
-import { can, CSRF_FIELD, GuardError, type PageChrome, parseListQuery, readFormBody, type RouteHandler, tracedFetch } from "../../src/plugin-api.ts";
+import { can, CSRF_FIELD, GuardError, type PageChrome, parseListQuery, readFormBody, type RouteHandler, tracedFetch } from "../../src/plugin-host/plugin-api.ts";
 
 export const SCHEDULING_PATH = "/scheduling"; // the plugin's public overview page
 export const SHIFTS_PATH = "/scheduling/shifts";