inspector/core/react/usePagedRequestorTasks.ts
cliffhall 50502269f4 fix(core): read state stores during render instead of re-syncing in an effect
Every state-subscription hook in core/react/ seeded local React state from
its store prop and re-synced it inside a useEffect. That shape paints one
frame of the previous store's data when the prop changes (switching
servers), and loses any event dispatched between the render that took the
snapshot and the effect that attached the listener.

Convert all 16 to useSyncExternalStore through a new shared
useStoreSnapshot, following useManagedListError (#1954).

useSyncExternalStore needs a referentially stable snapshot, and these
getters hand back a defensive copy, so TypedEventTarget now keeps a
per-event-type dispatch counter (getEventRevision) that the snapshot is
cached against. A contents comparison would not do: MessageLogState folds
a response into its request entry by mutating that entry in place, which a
shallow compare reports as unchanged. The bump lives on the dispatchEvent
override so no dispatch — including a hand-rolled CustomEvent — can bypass
it.

useInspectorClient is included though the issue did not list it; its nine
subscribed slices made the stale frame most visible. Its lastError stays
useState (accumulated from events, no getter to read back) but resets on
client swap during render rather than in an effect.

The settings-draft and async fetch hooks are deliberately untouched: the
former hold genuinely local editable state, the latter are I/O rather than
store subscriptions.

Also answers the issue's open question. react-hooks/set-state-in-effect
never fired here because eslint-plugin-react-hooks has never linted
core/react/ at all — it is a clients/web devDependency and the root config
loads no React plugin. Corrected the config comment that gave "no JSX" as
the reason; the gap itself is #2192, measured at 15 findings, none of them
in the hooks converted here.

Closes #1955

Signed-off-by: cliffhall <cliff@futurescale.com>
2026-08-29 02:07:53 -04:00

68 lines
2.2 KiB
TypeScript

import { useCallback } from "react";
import type { InspectorClientProtocol } from "../mcp/inspectorClientProtocol.js";
import type {
PagedRequestorTasksState,
LoadPageResult,
} from "../mcp/state/pagedRequestorTasksState.js";
import type { Task } from "@modelcontextprotocol/client";
import { useStoreSnapshot } from "./useStoreSnapshot.js";
/**
* Shared stable empty list for the no-server case. Module scope so the
* snapshot doesn't change identity every render — see `useStoreSnapshot`.
* Read-only by contract: nothing mutates a list this hook returns.
*/
const NO_TASKS: Task[] = [];
const readTasks = (state: PagedRequestorTasksState): Task[] => state.getTasks();
// This store has no dedicated pagination event — the cursor advances with the
// page, so it rides `tasksChange` like the list does.
const readNextCursor = (state: PagedRequestorTasksState): string | undefined =>
state.getNextCursor() ?? undefined;
export interface UsePagedRequestorTasksResult {
tasks: Task[];
loadPage: (cursor?: string) => Promise<LoadPageResult>;
clear: () => void;
nextCursor: string | undefined;
}
/**
* React hook that subscribes to PagedRequestorTasksState and returns tasks,
* loadPage, clear, and nextCursor.
*/
export function usePagedRequestorTasks(
client: InspectorClientProtocol | null,
pagedRequestorTasksState: PagedRequestorTasksState | null,
): UsePagedRequestorTasksResult {
const tasks = useStoreSnapshot(
pagedRequestorTasksState,
"tasksChange",
readTasks,
NO_TASKS,
);
const nextCursor = useStoreSnapshot(
pagedRequestorTasksState,
"tasksChange",
readNextCursor,
undefined,
);
const loadPage = useCallback(
async (cursor?: string): Promise<LoadPageResult> => {
if (!pagedRequestorTasksState || !client) {
return { tasks: NO_TASKS, nextCursor: undefined };
}
// The store dispatches `tasksChange` as it commits the page, so both
// snapshots above update on their own.
return pagedRequestorTasksState.loadPage(cursor);
},
[client, pagedRequestorTasksState],
);
const clear = useCallback(() => {
pagedRequestorTasksState?.clear();
}, [pagedRequestorTasksState]);
return { tasks, loadPage, clear, nextCursor };
}