feat(ri-050): RI-5-001 typed freshness states and stale-safe Mission Control surfaces (#1275) (#1300)

2026-08-18 05:56:58 +00:00
parent d92de53399
commit 7c7dab3898
15 changed files with 2525 additions and 188 deletions
@@ -0,0 +1,281 @@
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
+import {
+  acceptSnapshot,
+  assertMutable,
+  computeFreshness,
+  DEFAULT_FRESHNESS_POLICY,
+  invalidationReasonLabels,
+  type FreshPayload,
+  type FreshSnapshot,
+  type FreshnessPolicy,
+  type FreshnessState,
+  type InvalidationReason,
+  StaleMutationError,
+} from './model';
+import { clearSnapshotCache, readSnapshotCache, writeSnapshotCache } from './snapshot-cache';
+
+/**
+ * Freshness-aware collection fetch hook (RI-5-001).
+ *
+ * One hook owns one gateway collection end to end: fetch, schema validation,
+ * snapshot acceptance with provenance, session-scoped last-known caching,
+ * aging, and the mutation guard. Pages consume `freshness` and never infer
+ * health from emptiness.
+ */
+
+/** Why the latest validation did not produce a current snapshot. */
+export type FreshnessFailure =
+  | { readonly kind: 'fetch'; readonly message: string }
+  | { readonly kind: 'invalidated'; readonly reason: InvalidationReason };
+
+export interface UseFreshCollectionOptions<T> {
+  /** Source identity for provenance labels, e.g. `gateway:/api/tasks`. */
+  readonly source: string;
+  /** Performs the unvalidated fetch. The hook owns abort and verification. */
+  readonly fetcher: (signal: AbortSignal) => Promise<unknown>;
+  /**
+   * Runtime schema validator. Returning `null` invalidates the payload
+   * (`schema-mismatch`) instead of letting malformed JSON flow into render.
+   */
+  readonly validate: (value: unknown) => FreshPayload<T> | null;
+  /** Overrides of the default freshness policy. */
+  readonly policy?: Partial<FreshnessPolicy>;
+  /**
+   * Session cache key for last-known snapshots. `null`/omitted disables
+   * restore. Restored snapshots are unverified: they render only as
+   * labeled `stale` data until a fetch re-verifies them.
+   */
+  readonly cacheKey?: string | null;
+  /** Injectable clock for deterministic age transitions in tests. */
+  readonly clock?: () => number;
+  /** Aging tick interval override (default derived from `staleAfterMs`). */
+  readonly tickMs?: number;
+  /** When false, no fetch runs (surfaces stay `unavailable`/`unknown`). */
+  readonly enabled?: boolean;
+}
+
+export interface FreshCollection<T> {
+  /** Last verified (or restored-unverified) snapshot, or `null`. */
+  readonly snapshot: FreshSnapshot<T> | null;
+  /** Snapshot data or `null` — never a fabricated empty collection. */
+  readonly data: T | null;
+  readonly freshness: FreshnessState;
+  /** True while a validation request is in flight. */
+  readonly validating: boolean;
+  /** Outcome of the latest failed validation, `null` when healthy. */
+  readonly failure: FreshnessFailure | null;
+  /** False unless freshness is `current`; drives disabled UI affordances. */
+  readonly canMutate: boolean;
+  /** Re-run the fetch and re-verify. Always allowed (it is a read). */
+  readonly revalidate: () => Promise<void>;
+  /**
+   * Run a state-changing operation against verified-current data only.
+   * Rejects with `StaleMutationError` on any other state — the guard fires
+   * even if a disabled button was bypassed (defense in depth).
+   */
+  readonly mutate: <R>(operation: (data: T) => Promise<R>) => Promise<R>;
+}
+
+const defaultClock = (): number => Date.now();
+
+function resolveTickMs(policy: FreshnessPolicy, override?: number): number {
+  if (override !== undefined && override > 0) return override;
+  return Math.min(5_000, Math.max(250, Math.floor(policy.staleAfterMs / 4)));
+}
+
+function isAuthFailure(caught: unknown): boolean {
+  return (
+    typeof caught === 'object' &&
+    caught !== null &&
+    'statusCode' in caught &&
+    ((caught as { statusCode?: unknown }).statusCode === 401 ||
+      (caught as { statusCode?: unknown }).statusCode === 403)
+  );
+}
+
+function fetchFailureMessage(caught: unknown): string {
+  if (caught instanceof Error && caught.message.trim().length > 0) return caught.message;
+  return 'The request failed.';
+}
+
+/** Human-readable summary of a failure for unavailable/stale notices. */
+export function describeFailure(failure: FreshnessFailure | null): string | null {
+  if (failure === null) return null;
+  if (failure.kind === 'fetch') return failure.message;
+  return `The snapshot was invalidated: ${invalidationReasonLabels[failure.reason]}.`;
+}
+
+export function useFreshCollection<T>(options: UseFreshCollectionOptions<T>): FreshCollection<T> {
+  const optionsRef = useRef(options);
+  optionsRef.current = options;
+
+  const policy = useMemo<FreshnessPolicy>(
+    () => ({ ...DEFAULT_FRESHNESS_POLICY, ...options.policy }),
+    [options.policy],
+  );
+  const policyRef = useRef(policy);
+  policyRef.current = policy;
+
+  const clockRef = useRef(options.clock ?? defaultClock);
+  clockRef.current = options.clock ?? defaultClock;
+
+  const [snapshot, setSnapshot] = useState<FreshSnapshot<T> | null>(null);
+  const [failure, setFailure] = useState<FreshnessFailure | null>(null);
+  const [unverified, setUnverified] = useState(false);
+  const [validating, setValidating] = useState(options.enabled !== false);
+  const [now, setNow] = useState(() => (options.clock ?? defaultClock)());
+
+  const snapshotRef = useRef(snapshot);
+  snapshotRef.current = snapshot;
+  const failureRef = useRef(failure);
+  failureRef.current = failure;
+  const unverifiedRef = useRef(unverified);
+  unverifiedRef.current = unverified;
+
+  const runRef = useRef(0);
+  const abortRef = useRef<AbortController | null>(null);
+
+  const revalidate = useCallback(async (): Promise<void> => {
+    const current = optionsRef.current;
+    if (current.enabled === false) {
+      setValidating(false);
+      return;
+    }
+
+    const runId = ++runRef.current;
+    abortRef.current?.abort();
+    const controller = new AbortController();
+    abortRef.current = controller;
+    setValidating(true);
+
+    let value: unknown;
+    try {
+      value = await current.fetcher(controller.signal);
+    } catch (caught) {
+      if (runRef.current !== runId || controller.signal.aborted) return;
+      if (isAuthFailure(caught)) {
+        // An unauthenticated viewer must not keep (or be served) the
+        // previous user's last-known data.
+        setSnapshot(null);
+        setUnverified(false);
+        if (current.cacheKey) clearSnapshotCache(current.cacheKey);
+      }
+      setFailure({ kind: 'fetch', message: fetchFailureMessage(caught) });
+      setValidating(false);
+      return;
+    }
+
+    if (runRef.current !== runId) return;
+
+    const result = acceptSnapshot({
+      value,
+      validate: current.validate,
+      previous: snapshotRef.current,
+      policy: policyRef.current,
+      source: current.source,
+      now: clockRef.current(),
+    });
+
+    if (result.outcome === 'accepted') {
+      setSnapshot(result.snapshot);
+      setUnverified(false);
+      setFailure(null);
+      if (current.cacheKey) writeSnapshotCache(current.cacheKey, result.snapshot);
+    } else {
+      if (result.reason === 'cross-workspace') {
+        // Data verified for a different workspace must not linger as
+        // last-known situational awareness either.
+        setSnapshot(null);
+        setUnverified(false);
+      }
+      if (current.cacheKey) clearSnapshotCache(current.cacheKey);
+      setFailure({ kind: 'invalidated', reason: result.reason });
+    }
+    setValidating(false);
+  }, []);
+
+  // Restore the last-known snapshot (unverified) and run the first fetch.
+  useEffect(() => {
+    if (optionsRef.current.enabled === false) {
+      setValidating(false);
+      return;
+    }
+
+    const cacheKey = optionsRef.current.cacheKey;
+    if (cacheKey) {
+      const restored = readSnapshotCache<T>({
+        key: cacheKey,
+        workspace: policyRef.current.workspace,
+        policy: policyRef.current,
+        validate: optionsRef.current.validate,
+      });
+      if (restored.outcome === 'hit') {
+        setSnapshot(restored.snapshot);
+        setUnverified(true);
+      } else if (restored.outcome === 'invalidated') {
+        // A corrupted/foreign/regressed entry is dropped immediately; it must
+        // never surface as data. The fetch decides the visible state.
+        clearSnapshotCache(cacheKey);
+      }
+    }
+
+    void revalidate();
+
+    return () => {
+      abortRef.current?.abort();
+    };
+    // Mount-once by design: `revalidate` is stable and reads live options
+    // through refs, so it never needs to re-run when options change.
+    // Route-param pages remount this hook via an identity `key` instead.
+  }, [revalidate]);
+
+  // Aging tick: recomputes freshness as the snapshot ages past the policy.
+  useEffect(() => {
+    const interval = setInterval(
+      () => {
+        setNow(clockRef.current());
+      },
+      resolveTickMs(policyRef.current, optionsRef.current.tickMs),
+    );
+    return () => clearInterval(interval);
+  }, []);
+
+  const freshness = useMemo<FreshnessState>(() => {
+    if (snapshot === null) return validating ? 'unknown' : 'unavailable';
+    return computeFreshness({
+      snapshot,
+      policy,
+      now,
+      degraded: failure !== null || unverified,
+    });
+    // `now` from state covers age; refs inside computeFreshness are pure.
+  }, [snapshot, validating, failure, unverified, now, policy]);
+
+  const canMutate = freshness === 'current';
+
+  const mutate = useCallback(async <R>(operation: (data: T) => Promise<R>): Promise<R> => {
+    const currentSnapshot = snapshotRef.current;
+    // No verified snapshot at all: with nothing verified there is nothing
+    // current to mutate, regardless of the recorded failure.
+    if (currentSnapshot === null) throw new StaleMutationError('unavailable');
+    const state = computeFreshness({
+      snapshot: currentSnapshot,
+      policy: policyRef.current,
+      now: clockRef.current(),
+      degraded: failureRef.current !== null || unverifiedRef.current,
+    });
+    assertMutable(state);
+    return operation(currentSnapshot.data);
+  }, []);
+
+  return {
+    snapshot,
+    data: snapshot === null ? null : snapshot.data,
+    freshness,
+    validating,
+    failure,
+    canMutate,
+    revalidate,
+    mutate,
+  };
+}