milestone 29: activity — history, live and policy simulation on one surface

query log, live and lookup merge into /activity. history filters live
in the url, so a pasted link or back/forward reproduces the exact
view; the result column separates servfail and nxdomain from success
in the list. live is follow-by-default with freeze, and a streamed
row opens its in-memory provenance detail — no correlation invented
for rows sqlite has not written. lookup survives as the current
policy simulation under /activity/test. investigation links carry
absolute bounds, and the diagnostics page now honors since/until
instead of ignoring them. the old routes are gone without aliases.

admin/src/features/activity/search.ts

@@ -0,0 +1,88 @@
+/**
+ * The Activity search parameters, validated as pure functions so the route's
+ * `validateSearch` stays a one-liner and every rejection is testable without a
+ * router.
+ *
+ * A search value arrives from a URL, from history state, or from a hand-typed
+ * link, so nothing about its type is given. Anything that is not exactly the
+ * value the API can filter on becomes `undefined`: an unbounded page is honest,
+ * a page filtered on a coerced guess is not.
+ */
+
+import type { QueriesFilter } from "@/lib/types";
+
+export const ACTIVITY_MODES = ["history", "live"] as const;
+export type ActivityMode = (typeof ACTIVITY_MODES)[number];
+
+export interface ActivitySearch {
+	mode: ActivityMode;
+	since: number | undefined;
+	until: number | undefined;
+	domain: string | undefined;
+	client: string | undefined;
+	blocked: boolean | undefined;
+}
+
+/** History is the surface a bare `/activity` should open on: it answers questions. */
+export function validateMode(value: unknown): ActivityMode {
+	return value === "live" ? "live" : "history";
+}
+
+/**
+ * A unix-second bound. `Number.isSafeInteger` is the whole test: it rejects a
+ * fraction, an infinity, a NaN and a magnitude past 2^53 in one step, and a
+ * string never passes, so `?since=now` cannot reach the API as garbage.
+ */
+export function validateTimestamp(value: unknown): number | undefined {
+	return Number.isSafeInteger(value) ? (value as number) : undefined;
+}
+
+/**
+ * The blocked filter. `false` is a real filter — "allowed only" — so it must
+ * survive; only a genuine boolean does, because `"false"` out of a URL parser
+ * that did not decode JSON would otherwise read as true.
+ */
+export function validateBlocked(value: unknown): boolean | undefined {
+	return typeof value === "boolean" ? value : undefined;
+}
+
+/**
+ * A text filter, trimmed. An empty result becomes `undefined` rather than `""`:
+ * the server treats an empty filter as no filter, and a URL that showed
+ * `domain=` as applied state would claim a filter that is not filtering.
+ */
+export function validateText(value: unknown): string | undefined {
+	if (typeof value !== "string") return undefined;
+	const trimmed = value.trim();
+	return trimmed === "" ? undefined : trimmed;
+}
+
+/**
+ * The API filter for a validated search, built field by field.
+ *
+ * Only the fields that are actually set are written, so an unfiltered request
+ * carries no keys at all: `GET /api/queries` rejects a parameter it does not
+ * know, and the infinite query's cache key is the filter object, so a key
+ * present-but-undefined and a key absent must not be two different windows onto
+ * the same rows. `mode` never appears — it selects the surface, not the rows.
+ */
+export function queriesFilterOf(search: Omit<ActivitySearch, "mode">): QueriesFilter {
+	const filter: QueriesFilter = {};
+	if (search.domain !== undefined) filter.domain = search.domain;
+	if (search.client !== undefined) filter.client = search.client;
+	if (search.blocked !== undefined) filter.blocked = search.blocked;
+	if (search.since !== undefined) filter.since = search.since;
+	if (search.until !== undefined) filter.until = search.until;
+	return filter;
+}
+
+export function validateActivitySearch(search: Record<string, unknown>): ActivitySearch {
+	return {
+		mode: validateMode(search["mode"]),
+		since: validateTimestamp(search["since"]),
+		until: validateTimestamp(search["until"]),
+		domain: validateText(search["domain"]),
+		client: validateText(search["client"]),
+		blocked: validateBlocked(search["blocked"]),
+	};
+}