From 0c6f3a97a1d3935066abfe5fd42a0f41b5aad00c Mon Sep 17 00:00:00 2001
From: Jorge Rivera <jorge.rivera@one.org>
Date: Wed, 21 Oct 2026 19:03:35 +0200
Subject: [PATCH] refactor(search): type the search spec, part and binding
 parameters

The DataSearch components and the src/lib/search helpers take the
page's Spec, Part and Slot types where they took any, so a reader that
skips an absent member fails to compile. SpecReading is
Partial<Spec> | UnreadableSpec, and an unreadable spec's stat_vars is
unknown, so StatVars reach a reader only through readStatVars.

A spec flagged statVarsUnreadable supplies no StatVar count, years or
members from the value that failed validation. priceBasis reads a
prices value other than current or constant as unknown, and
withResolvedSlotEdit returns the identity unchanged for a spec with no
slots. Test fixtures go through partialSpec and partialSlot, which take
a deep partial of the wire type; two fixtures that named non-members of
ObservationSeries now name stat_var.
---
 .../organisms/DataSearch/ReadingCards.tsx     |   7 +-
 .../organisms/DataSearch/SearchCards.tsx      |   9 +-
 .../organisms/DataSearch/SearchPanel.tsx      |   4 +-
 .../organisms/DataSearch/SearchSentence.tsx   |  47 ++-
 .../organisms/DataSearch/SearchTable.tsx      |   5 +-
 .../organisms/DataSearch/UnitPicker.tsx       |   5 +-
 .../organisms/DataSearch/WhyPanel.tsx         |   4 +-
 .../organisms/DataSearch/editors.tsx          |  43 +-
 .../organisms/DataSearch/useSearchRun.ts      |  23 +-
 src/lib/search/measureMenu.ts                 |   6 +-
 src/lib/search/promote.ts                     |   5 +-
 src/lib/search/refineMenu.ts                  |  13 +-
 src/lib/search/resultNotes.ts                 |  12 +-
 src/lib/search/searchClient.ts                |   4 +-
 src/lib/search/test/fixtures/partial.ts       |  23 +
 src/lib/search/test/fixtures/served-answer.ts |  22 +-
 src/lib/search/test/origin.test.ts            |  76 ++--
 src/lib/search/test/previewColumns.test.ts    |   2 +-
 src/lib/search/test/refineMenu.test.ts        |   8 +-
 src/lib/search/test/resultNotes.test.ts       |  30 +-
 src/lib/search/test/tokenAbout.test.ts        |  70 ++--
 src/lib/search/test/unitLabel.test.ts         |  44 +-
 src/lib/search/test/unitPicker.test.ts        |  30 +-
 src/lib/search/test/view.test.ts              |  89 ++--
 src/lib/search/test/why.test.ts               | 171 +++++---
 src/lib/search/tokenAbout.ts                  |  81 ++--
 src/lib/search/types.ts                       |  12 +-
 src/lib/search/unitLabel.ts                   |  31 +-
 src/lib/search/unitPicker.ts                  |  19 +-
 src/lib/search/view.ts                        | 393 +++++++++++-------
 30 files changed, 776 insertions(+), 512 deletions(-)
 create mode 100644 src/lib/search/test/fixtures/partial.ts

diff --git a/src/components/organisms/DataSearch/ReadingCards.tsx b/src/components/organisms/DataSearch/ReadingCards.tsx
index a91c00c..4ce4081 100644
--- a/src/components/organisms/DataSearch/ReadingCards.tsx
+++ b/src/components/organisms/DataSearch/ReadingCards.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes candidate specs as `any` and reads only the members it renders, tolerating any that is missing */
 'use client';
 
 import { useMemo } from 'react';
@@ -10,7 +9,7 @@ import Button from '@/components/atoms/Button/Button';
 import { isClosestMatch } from '@/lib/search/departures';
 import { basisNote, readingOf, readingsSummary } from '@/lib/search/readings';
 import { tokenAbout } from '@/lib/search/tokenAbout';
-import type { CandidatesPart } from '@/lib/search/types';
+import type { CandidatesPart, Spec } from '@/lib/search/types';
 import { statVarsUnreadable } from '@/lib/search/view';
 
 /**
@@ -32,11 +31,11 @@ const ReadingCards = ({
     part: CandidatesPart;
     // The part's variable text, when the answer has several parts.
     prefix: string | null;
-    onPick: (spec: any) => void;
+    onPick: (spec: Spec) => void;
     // Re-runs the question, for a reading the client could not read.
     onRetry: () => void;
 }) => {
-    const specs: any[] = useMemo(() => part.candidates.specs, [part]);
+    const specs = useMemo(() => part.candidates.specs, [part]);
     const readings = useMemo(
         () =>
             specs.map((spec) => {
diff --git a/src/components/organisms/DataSearch/SearchCards.tsx b/src/components/organisms/DataSearch/SearchCards.tsx
index a7e6627..24ead24 100644
--- a/src/components/organisms/DataSearch/SearchCards.tsx
+++ b/src/components/organisms/DataSearch/SearchCards.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes specs as `any` and reads only the members it renders, tolerating any that is missing */
 'use client';
 
 import classNames from 'classnames';
@@ -21,12 +20,12 @@ import {
     specOrigin,
     statVarsUnreadable,
 } from '@/lib/search/view';
-import { knownPart, type ParsedPart, type Part } from '@/lib/search/types';
+import { knownPart, type ParsedPart, type Part, type PartSpec } from '@/lib/search/types';
 
 // A card's meta line, its coverage then its origin (specOrigin beside the
 // spec's own sentence, shapeOrigin beside any other title). The line clamps
 // at two lines, so the full text goes in the title attribute.
-const CardMeta = ({ spec, origin }: { spec: any; origin: string | null }) => {
+const CardMeta = ({ spec, origin }: { spec: PartSpec; origin: string | null }) => {
     const meta = [coverageSummary(spec), origin].filter(Boolean).join(' · ');
 
     return (
@@ -97,7 +96,7 @@ const SearchCards = ({
                     Multiple possible interpretations found. Select the best fit…
                 </p>
                 <div className={styles.cards}>
-                    {specs.map((spec: any, index: number) => (
+                    {specs.map((spec, index) => (
                         <button
                             key={spec.spec_id}
                             type="button"
@@ -206,7 +205,7 @@ const SearchCards = ({
             <div className={styles.cardsBlock}>
                 <p className={styles.cardsTitle}>Largest Subsets</p>
                 <div className={styles.cards}>
-                    {nearest.map((spec: any, index: number) => {
+                    {nearest.map((spec, index) => {
                         const unreadable = statVarsUnreadable(spec);
 
                         // A shape the client couldn't parse has no title to
diff --git a/src/components/organisms/DataSearch/SearchPanel.tsx b/src/components/organisms/DataSearch/SearchPanel.tsx
index 6db68b2..6160d8c 100644
--- a/src/components/organisms/DataSearch/SearchPanel.tsx
+++ b/src/components/organisms/DataSearch/SearchPanel.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes the spec as `any` and reads only the members the panel renders, tolerating any that is missing */
 'use client';
 
 import classNames from 'classnames';
@@ -11,6 +10,7 @@ import { type DatasetDownloaded, useDatasetDownload } from './useDatasetDownload
 
 import Button from '@/components/atoms/Button/Button';
 import { usePrefersReducedMotion } from '@/hooks/usePrefersReducedMotion';
+import type { PartSpec } from '@/lib/search/types';
 import { detailRows, downloadRowCount, formatCount } from '@/lib/search/view';
 
 import { SourceName } from './WhyPanel';
@@ -24,7 +24,7 @@ const SearchPanel = ({
     onStudio,
     onDownloadStart,
 }: {
-    spec: any;
+    spec: PartSpec;
     // Says a download may differ from the preview (resultNotes downloadNote).
     note?: string | null;
     // Mints this result's share links; the Share button is hidden without it.
diff --git a/src/components/organisms/DataSearch/SearchSentence.tsx b/src/components/organisms/DataSearch/SearchSentence.tsx
index 3ee7109..09875b9 100644
--- a/src/components/organisms/DataSearch/SearchSentence.tsx
+++ b/src/components/organisms/DataSearch/SearchSentence.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes specs, slots and options of either picker shape as `any` and reads only the members it renders, tolerating any that is missing */
 'use client';
 
 import * as DropdownMenu from '@radix-ui/react-dropdown-menu';
@@ -73,8 +72,10 @@ import {
     type NoDataOption,
     type ParsedPart,
     type PartSpec,
+    type Resolution,
     type RoleAxis,
     type SentenceToken,
+    type Slot,
     type SlotOption,
     type SpecAlternativeMeasure,
 } from '@/lib/search/types';
@@ -251,9 +252,9 @@ const MethodChoices = ({
  * already scoped to its own level.
  */
 const renderLevelOptions = (
-    slot: any,
+    slot: Slot,
     options: readonly SlotOption[],
-    onSelect: (binding: any) => void,
+    onSelect: (binding: Slot['binding']) => void,
 ) => {
     const optionItem = (option: SlotOption, direction?: 'up' | 'down') => (
         <DropdownMenu.Item
@@ -321,7 +322,11 @@ const renderLevelOptions = (
  * total, so the hint never implies a count. Each option carries the
  * graph's definition behind an info icon.
  */
-const renderOptionMenu = (slot: any, entry: SlotOptionsEntry, onSelect: (binding: any) => void) => {
+const renderOptionMenu = (
+    slot: Slot,
+    entry: SlotOptionsEntry,
+    onSelect: (binding: Slot['binding']) => void,
+) => {
     const { options, truncated } = entry;
 
     return (
@@ -345,12 +350,12 @@ const FlatOptionList = ({
     options,
     onSelect,
 }: {
-    slot: any;
+    slot: Slot;
     options: SlotOption[];
-    onSelect: (binding: any) => void;
+    onSelect: (binding: Slot['binding']) => void;
 }) => {
     const [filter, setFilter] = useState('');
-    const boundDcid = slot.binding?.value?.ref?.ref;
+    const boundDcid = slot.binding.kind === 'value' ? slot.binding.value.ref?.ref : undefined;
     const { current, rest } = splitCurrentPick(options, boundDcid);
     const showFilter = shouldShowOptionFilter(rest.length);
     const shown = showFilter
@@ -405,7 +410,7 @@ const FlatOptionList = ({
 };
 
 type SearchSentenceProps = {
-    response: any;
+    response: Resolution | null;
     // Every part, in query order — the token routing target for a
     // part-indexed slot, and the source of the definite/candidates/no_data/
     // unsupported status a marked phrase reads.
@@ -427,13 +432,18 @@ type SearchSentenceProps = {
     baseStreamOpen: boolean;
     onEditSlot: (
         partIndex: number,
-        spec: any,
+        spec: PartSpec,
         slotIndex: number,
-        binding: any,
+        binding: Slot['binding'],
         entityRole?: EntityRoleKey,
     ) => void;
-    onEditEntity: (partIndex: number, spec: any, role: RoleAxis, dcids: string[] | null) => void;
-    onEditWindow: (partIndex: number, spec: any, window: WindowApplyValue) => void;
+    onEditEntity: (
+        partIndex: number,
+        spec: PartSpec,
+        role: RoleAxis,
+        dcids: string[] | null,
+    ) => void;
+    onEditWindow: (partIndex: number, spec: PartSpec, window: WindowApplyValue) => void;
     // An alternative measure, or a related one from the variable's group,
     // on each part a pick switches (several for a shared unit token).
     onEditMeasure: (picks: readonly MeasurePick[]) => void;
@@ -441,7 +451,7 @@ type SearchSentenceProps = {
     // price basis).
     onEditFacet: <A extends IdentityFacetAxis>(
         partIndex: number,
-        spec: any,
+        spec: PartSpec,
         axis: A,
         binding: IdentityFacetBinding[A] | null,
     ) => void;
@@ -531,7 +541,7 @@ const placeField = (token: SentenceToken): string =>
 
 /** The field an option-list slot edits ("Sector"), for its menu title and
  *  its trigger's accessible name. */
-const slotField = (slot: any): string => slot.key.label ?? 'Value';
+const slotField = (slot: Slot): string => slot.key.label ?? 'Value';
 
 // The ref a token's menu changes when it edits the one binding the token
 // carries: its binding_ref, or none.
@@ -666,8 +676,9 @@ const EntityOptionRows = ({
 /** The composed sentence as displayed, notes left out. It names the hero
  *  <h1>, which would otherwise take its name from each slot trigger's longer
  *  accessible name. */
-export const sentenceHeadingText = (response: any): string =>
-    planSentenceText(response?.sentence_plan);
+export const sentenceHeadingText = (
+    response: Pick<Resolution, 'sentence_plan'> | null | undefined,
+): string => planSentenceText(response?.sentence_plan);
 
 /** The space between two heading blocks of a plan of separate sentences. */
 const HEADING_JOIN: SentenceToken = { kind: 'text', text: ' ', segment: 'heading' };
@@ -1443,7 +1454,7 @@ export const SearchSentenceHeading = ({
         }
 
         const slot = slots[slotIndex];
-        const onSelect = (binding: any) =>
+        const onSelect = (binding: Slot['binding']) =>
             onEditSlot(partIndex, spec, slotIndex, binding, token.role ?? 'observationAbout');
         // A level-scoped constraint slot (relation populated) skips the
         // free-text escape hatch renderOptionMenu's flat branch offers —
@@ -2232,7 +2243,7 @@ const RefineEntry = ({
     }
 
     const { slot, slotIndex, entry, current } = item;
-    const onSelect = (binding: any) => onEditSlot(part.index, spec, slotIndex, binding);
+    const onSelect = (binding: Slot['binding']) => onEditSlot(part.index, spec, slotIndex, binding);
     const [only] = entry.options;
 
     // An unbound slot with one option: its row picks it.
diff --git a/src/components/organisms/DataSearch/SearchTable.tsx b/src/components/organisms/DataSearch/SearchTable.tsx
index 1ed0295..8b1efe7 100644
--- a/src/components/organisms/DataSearch/SearchTable.tsx
+++ b/src/components/organisms/DataSearch/SearchTable.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes the spec as `any` and reads only the members the table renders, tolerating any that is missing */
 'use client';
 
 import classNames from 'classnames';
@@ -24,12 +23,12 @@ import {
     resolveObservationsOmission,
 } from '@/lib/search/view';
 import { tableCaptionNotes } from '@/lib/search/resultNotes';
-import type { Warning } from '@/lib/search/types';
+import type { PartSpec, Warning } from '@/lib/search/types';
 
 type TablePart = {
     index: number;
     variableText: string | null;
-    spec: any;
+    spec: PartSpec;
     warnings?: Pick<Warning, 'code' | 'message' | 'params'>[];
 };
 
diff --git a/src/components/organisms/DataSearch/UnitPicker.tsx b/src/components/organisms/DataSearch/UnitPicker.tsx
index 4b70de5..48deb88 100644
--- a/src/components/organisms/DataSearch/UnitPicker.tsx
+++ b/src/components/organisms/DataSearch/UnitPicker.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the flattened wire Spec */
 'use client';
 
 import * as DropdownMenu from '@radix-ui/react-dropdown-menu';
@@ -10,7 +9,7 @@ import { OptionRow, stopMenuFieldTypeahead } from './SlotMenu';
 
 import Button from '@/components/atoms/Button/Button';
 import { currencyName } from '@/lib/search/tokenAbout';
-import type { IdentityUnitRequest, UnitConversion } from '@/lib/search/types';
+import type { IdentityUnitRequest, PartSpec, UnitConversion } from '@/lib/search/types';
 import {
     currencyMatches,
     currencyRequest,
@@ -44,7 +43,7 @@ export const UnitPicker = ({
     conversion,
     onPick,
 }: {
-    spec: any;
+    spec: PartSpec;
     conversion: UnitConversion;
     onPick: (request: IdentityUnitRequest) => void;
 }) => {
diff --git a/src/components/organisms/DataSearch/WhyPanel.tsx b/src/components/organisms/DataSearch/WhyPanel.tsx
index 5682dec..dbcf373 100644
--- a/src/components/organisms/DataSearch/WhyPanel.tsx
+++ b/src/components/organisms/DataSearch/WhyPanel.tsx
@@ -10,7 +10,7 @@ import Button from '@/components/atoms/Button/Button';
 import Icon from '@/components/atoms/Icon/Icon';
 import SourceLink from '@/components/atoms/SourceLink/SourceLink';
 import { aboutAnswerNotes, type AboutAnswerNotes } from '@/lib/search/resultNotes';
-import type { Assumption, Warning } from '@/lib/search/types';
+import type { Assumption, PartSpec, Warning } from '@/lib/search/types';
 import {
     buildWhySummary,
     formatCount,
@@ -149,7 +149,7 @@ const NoteGroup = ({ title, notes }: { title: string; notes: string[] }) =>
 export type AboutPart = {
     index: number;
     variableText: string | null;
-    spec: Parameters<typeof buildWhySummary>[0];
+    spec: PartSpec;
     warnings?: Warning[];
     assumptions?: Assumption[];
 };
diff --git a/src/components/organisms/DataSearch/editors.tsx b/src/components/organisms/DataSearch/editors.tsx
index 043270f..b83c528 100644
--- a/src/components/organisms/DataSearch/editors.tsx
+++ b/src/components/organisms/DataSearch/editors.tsx
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes specs and options of either picker shape as `any` and reads only the members each editor shows, tolerating any that is missing */
 'use client';
 
 import * as DropdownMenu from '@radix-ui/react-dropdown-menu';
@@ -20,11 +19,17 @@ import Button from '@/components/atoms/Button/Button';
 import {
     filterOptionsByQuery,
     mergeEntitySeedWithFetch,
+    type OptionLike,
     shouldShowOptionFilter,
 } from '@/lib/search/pickerState';
 import type { ApiError, EntityOption } from '@/lib/search/searchClient';
 import { entityOptions } from '@/lib/search/searchClient';
-import type { EntityRoleKey, IdentityWindow, PlaceOptionsScope } from '@/lib/search/types';
+import type {
+    EntityRoleKey,
+    IdentityWindow,
+    PartSpec,
+    PlaceOptionsScope,
+} from '@/lib/search/types';
 import {
     buildPlaceOptionGroups,
     observationSeries,
@@ -56,7 +61,7 @@ export const WindowEditor = ({
     label,
     onApply,
 }: {
-    spec: any;
+    spec: PartSpec;
     label?: string;
     onApply: (value: WindowApplyValue) => void;
 }) => {
@@ -67,7 +72,7 @@ export const WindowEditor = ({
         .filter((year) => !Number.isNaN(year));
     const seed = seedWindowYears({
         requestedWindow,
-        coverageWindow: spec?.coverage?.window,
+        coverageWindow: spec?.coverage?.window ?? undefined,
         label,
         observationYears: years,
     });
@@ -206,7 +211,7 @@ const failureMessage = (error: ApiError): string => {
 
 type PlaceEditorState =
     | { phase: 'loading' }
-    | { phase: 'loaded'; groups: { title: string; options: any[] }[] }
+    | { phase: 'loaded'; groups: { title: string; options: EntityOption[] }[] }
     | { phase: 'failed'; error: ApiError };
 
 /** One PlaceEditor mount's decisions for its current (spec, anchor, role,
@@ -271,7 +276,7 @@ export const PlaceEditor = ({
     role,
     baseStreamOpen,
 }: {
-    spec: any;
+    spec: PartSpec;
     /** Keys this editor's reactive prefetch effect. Read boundDcids for the
      *  full pinned/checked set, this is never more than its first member. */
     anchorDcid: string;
@@ -379,7 +384,9 @@ export const PlaceEditor = ({
     const hasIdentity = !!spec.identity;
 
     useEffect(() => {
-        if (!hasIdentity) return;
+        const { identity } = spec;
+
+        if (!identity) return;
 
         const key = `${spec.spec_id}::${anchorDcid}::${role ?? ''}::${retryToken}`;
 
@@ -473,9 +480,7 @@ export const PlaceEditor = ({
             // latency to the second group. Group order (Similar places,
             // then Within) comes from `scopes`, not settle order.
             void Promise.allSettled(
-                scopesToFetch.map((scope) =>
-                    entityOptions({ identity: spec.identity, scope, role }),
-                ),
+                scopesToFetch.map((scope) => entityOptions({ identity, scope, role })),
             ).then((settled) => {
                 if (!current()) return;
 
@@ -560,7 +565,7 @@ export const PlaceEditor = ({
     const seenPinned = new Set<string>();
     const pinnedOptions = groupSplits
         .flatMap((group) => group.current)
-        .filter((option: any) => {
+        .filter((option) => {
             if (seenPinned.has(option.dcid)) return false;
             seenPinned.add(option.dcid);
             return true;
@@ -571,7 +576,7 @@ export const PlaceEditor = ({
     const filteredGroups = unfilteredGroups
         .map((group) => ({
             ...group,
-            options: filterOptionsByQuery(group.options, filter, (option: any) => option.label),
+            options: filterOptionsByQuery(group.options, filter, (option) => option.label),
         }))
         .filter((group) => group.options.length > 0);
     const unbindLabel = unbindRoleLabel(role);
@@ -580,7 +585,7 @@ export const PlaceEditor = ({
     // names a visible row would just duplicate that row's own click, so the
     // row is enough and the Search action stays hidden.
     const listedLabels = new Set(
-        [...pinnedOptions, ...filteredGroups.flatMap((group) => group.options)].map((option: any) =>
+        [...pinnedOptions, ...filteredGroups.flatMap((group) => group.options)].map((option) =>
             option.label.toLowerCase(),
         ),
     );
@@ -652,7 +657,7 @@ export const PlaceEditor = ({
                 closes the menu, same as any other row. */}
             {hasIdentity &&
                 state.phase === 'loaded' &&
-                pinnedOptions.map((option: any) => (
+                pinnedOptions.map((option) => (
                     <DropdownMenu.Item
                         key={option.dcid}
                         asChild
@@ -683,7 +688,7 @@ export const PlaceEditor = ({
                         {showGroupHeadings(unfilteredGroups) && (
                             <p className={styles.slotGroupTitle}>{group.title}</p>
                         )}
-                        {group.options.map((option: any) => (
+                        {group.options.map((option) => (
                             <DropdownMenu.Item
                                 key={option.dcid}
                                 asChild
@@ -737,7 +742,7 @@ export const PlaceEditor = ({
                     onApply={() => {
                         const labelByDcid = new Map(
                             loadedGroups.flatMap((group) =>
-                                group.options.map((option: any) => [option.dcid, option.label]),
+                                group.options.map((option) => [option.dcid, option.label]),
                             ),
                         );
 
@@ -774,7 +779,7 @@ const placeRoleLabel = (role: EntityRoleKey): string => {
 };
 
 const seededState = (
-    seed: { options: any[]; truncated: boolean } | undefined,
+    seed: { options: OptionLike[]; truncated: boolean } | undefined,
 ): PlaceScopeEditorState =>
     seed
         ? {
@@ -794,7 +799,7 @@ export const PlaceScopeEditor = ({
     rankingBlocked,
     offerAny,
 }: {
-    spec: any;
+    spec: PartSpec;
     role: EntityRoleKey;
     /** Multi-select mode: see PlaceEditor's own onApply/onSelect doc above.
      *  Exactly one of the two is passed by any caller. */
@@ -802,7 +807,7 @@ export const PlaceScopeEditor = ({
     /** Single-pick mode: a row click posts immediately and closes the menu,
      *  no toggle state, no Apply button. */
     onSelect?: (ref: { dcid: string; label: string }) => void;
-    seed?: { options: any[]; truncated: boolean };
+    seed?: { options: OptionLike[]; truncated: boolean };
     /** Split out of the merged list and shown once, above it, checked/
      *  pinned. Omitted (or []) for an unbound axis with no current pick to
      *  protect. */
diff --git a/src/components/organisms/DataSearch/useSearchRun.ts b/src/components/organisms/DataSearch/useSearchRun.ts
index 5e7d055..bc6577b 100644
--- a/src/components/organisms/DataSearch/useSearchRun.ts
+++ b/src/components/organisms/DataSearch/useSearchRun.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- takes the edited spec and slot bindings as `any`, passing members it does not read */
 'use client';
 
 /**
@@ -194,6 +193,7 @@ import {
     type EntityRoleKey,
     type ExpectedPart,
     type FacetOptionsEntry,
+    hasDefiniteSpec,
     type HydratedPart,
     type IdentityFacetAxis,
     type IdentityFacetBinding,
@@ -205,6 +205,7 @@ import {
     type ResolveResponse,
     type RoleAxis,
     type SentenceToken,
+    type Slot,
     type Spec,
     type SpecObservations,
 } from '@/lib/search/types';
@@ -1079,7 +1080,7 @@ export const useSearchRun = () => {
     );
 
     const identityOverrideEntry = useCallback(
-        (partIndex: number, fromSpec: any, identity: BaseIdentity): DatasetIdentityEntry => ({
+        (partIndex: number, fromSpec: PartSpec, identity: BaseIdentity): DatasetIdentityEntry => ({
             entry_kind: 'identity',
             variable_text: parts[partIndex]?.variableText ?? '',
             identity,
@@ -1094,9 +1095,9 @@ export const useSearchRun = () => {
     const editSlot = useCallback(
         (
             partIndex: number,
-            fromSpec: any,
+            fromSpec: PartSpec,
             slotIndex: number,
-            binding: any,
+            binding: Slot['binding'],
             entityRole: EntityRoleKey = 'observationAbout',
         ) => {
             const identity = withResolvedSlotEdit(fromSpec, slotIndex, binding, entityRole);
@@ -1110,7 +1111,7 @@ export const useSearchRun = () => {
     // A null/empty dcids is the unbind row or an Apply with nothing checked,
     // which drops the role from the identity.
     const editEntity = useCallback(
-        (partIndex: number, fromSpec: any, role: RoleAxis, dcids: string[] | null) => {
+        (partIndex: number, fromSpec: PartSpec, role: RoleAxis, dcids: string[] | null) => {
             const identity = withEntityEdit(fromSpec.identity as BaseIdentity, role, dcids);
             const entry = identityOverrideEntry(partIndex, fromSpec, identity);
 
@@ -1122,7 +1123,7 @@ export const useSearchRun = () => {
     // A deliberate date edit sets identity.requested_window directly. 'when'
     // is not an identity slot, so the edit needs no slot binding at all.
     const editWindow = useCallback(
-        (partIndex: number, fromSpec: any, window: WindowApplyValue) => {
+        (partIndex: number, fromSpec: PartSpec, window: WindowApplyValue) => {
             const identity: BaseIdentity = {
                 ...(fromSpec.identity as BaseIdentity),
                 requested_window: window,
@@ -1138,7 +1139,7 @@ export const useSearchRun = () => {
     const facetOverride = useCallback(
         <A extends IdentityFacetAxis>(
             partIndex: number,
-            fromSpec: any,
+            fromSpec: PartSpec,
             axis: A,
             binding: IdentityFacetBinding[A] | null,
         ): DatasetEntriesOverride => {
@@ -1157,7 +1158,7 @@ export const useSearchRun = () => {
     const editFacet = useCallback(
         <A extends IdentityFacetAxis>(
             partIndex: number,
-            fromSpec: any,
+            fromSpec: PartSpec,
             axis: A,
             binding: IdentityFacetBinding[A] | null,
         ) => {
@@ -1358,9 +1359,9 @@ export const useSearchRun = () => {
             // One override per part, each from its own identity. Only a choice every bound part offers goes
             // out (`sharedMethodServes`), the choices the shared menu lists.
             if (edit.axis === 'method') {
-                const bound = parts.filter(
-                    (part) => part.part?.status === 'definite' && bindsMethod(part.hydratedSpec),
-                );
+                const bound = parts
+                    .filter(hasDefiniteSpec)
+                    .filter((part) => bindsMethod(part.hydratedSpec));
 
                 if (
                     bound.length === 0 ||
diff --git a/src/lib/search/measureMenu.ts b/src/lib/search/measureMenu.ts
index f65c5a8..30487bd 100644
--- a/src/lib/search/measureMenu.ts
+++ b/src/lib/search/measureMenu.ts
@@ -26,10 +26,12 @@ import {
 
 export { openAxisFactLabel };
 
+/** The members the measure menu reads. An unreadable spec may lack `slots`. */
 export type MeasureMenuSpec = Pick<
     Spec,
-    'spec_id' | 'slots' | 'alternative_measures' | 'open_axis_facts' | 'download'
->;
+    'spec_id' | 'alternative_measures' | 'open_axis_facts' | 'download'
+> &
+    Partial<Pick<Spec, 'slots'>>;
 
 /** One group of the measure menu: a slot the measure token states, with
  *  its options. */
diff --git a/src/lib/search/promote.ts b/src/lib/search/promote.ts
index e780af9..61e55ff 100644
--- a/src/lib/search/promote.ts
+++ b/src/lib/search/promote.ts
@@ -9,6 +9,7 @@ import type {
     IdentityFacetBinding,
     IdentityFacets,
     Spec,
+    SpecReading,
 } from './types';
 
 // ---------------------------------------------------------------------------
@@ -131,13 +132,13 @@ export function withFacetEdit<A extends IdentityFacetAxis>(
  * onEditWindow directly.
  */
 export function withResolvedSlotEdit(
-    spec: Pick<Spec, 'identity' | 'slots'>,
+    spec: Pick<SpecReading, 'identity' | 'slots'>,
     slotIndex: number,
     binding: ResolvedBinding,
     entityRole: EntityRoleKey = 'observationAbout',
 ): BaseIdentity {
     const identity = spec.identity as BaseIdentity;
-    const slot = spec.slots[slotIndex];
+    const slot = spec.slots?.[slotIndex];
     const axis = slot?.key?.axis;
 
     if (axis === 'where') {
diff --git a/src/lib/search/refineMenu.ts b/src/lib/search/refineMenu.ts
index 19fd45f..d3788a2 100644
--- a/src/lib/search/refineMenu.ts
+++ b/src/lib/search/refineMenu.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads specs, slots and bindings as `any`, dereferencing only the members it names and tolerating any that is missing */
 /**
  * What Refine offers: the bindings of the answer's definite parts that no
  * visible token states (SentenceToken.states), each with something to pick:
@@ -9,7 +8,7 @@
 
 import { statingTokenIndex } from './departures.ts';
 import { keyRef } from './searchClient.ts';
-import type { RoleAxis, SentenceToken } from './types';
+import type { PartSpec, RoleAxis, SentenceToken, Slot } from './types';
 import {
     methodPicker,
     openEntityEntry,
@@ -24,7 +23,7 @@ import {
 } from './view.ts';
 
 /** A definite part as Refine reads it. */
-export type RefinePart = { index: number; variableText: string | null; spec: any };
+export type RefinePart = { index: number; variableText: string | null; spec: PartSpec };
 
 /** One Refine entry. `key` names it (`refineKey`), so a departure's action
  *  can open Refine at it. A bound slot or facet axis carries its `current`
@@ -34,7 +33,7 @@ export type RefineItem =
           kind: 'slot';
           key: string;
           part: RefinePart;
-          slot: any;
+          slot: Slot;
           slotIndex: number;
           entry: SlotOptionsEntry;
           current: string | null;
@@ -61,10 +60,10 @@ const EMPTY: SlotOptionsEntry = { options: [], truncated: false };
 
 // A bound slot's value as the reader names it: one label, or a set's
 // labels joined.
-const boundText = (binding: any): string | null => {
+const boundText = (binding: Slot['binding']): string | null => {
     if (binding?.kind === 'value') return optionLabel({ value: binding.value });
     if (binding?.kind === 'set') {
-        return (binding.values ?? []).map((value: any) => optionLabel({ value })).join(', ');
+        return (binding.values ?? []).map((value) => optionLabel({ value })).join(', ');
     }
 
     return null;
@@ -98,7 +97,7 @@ export function refineItems({
         const { spec } = part;
         const stated = (ref: string) => statingTokenIndex(plan, partCount, part.index, ref) !== -1;
 
-        const slots = (spec.slots ?? []).flatMap((slot: any, slotIndex: number): RefineItem[] => {
+        const slots = (spec.slots ?? []).flatMap((slot, slotIndex): RefineItem[] => {
             const ref = keyRef(slot.key);
             const entry: SlotOptionsEntry =
                 slot.key?.axis === 'source'
diff --git a/src/lib/search/resultNotes.ts b/src/lib/search/resultNotes.ts
index ce9e42a..43d4d0c 100644
--- a/src/lib/search/resultNotes.ts
+++ b/src/lib/search/resultNotes.ts
@@ -16,7 +16,7 @@ import {
     seriesPreviewCaptions,
     type SlotOptionsEntry,
 } from './view.ts';
-import type { Assumption, Warning } from './types.ts';
+import type { Assumption, NoDataPart, SpecReading, Warning } from './types.ts';
 
 const andList = (labels: string[]): string =>
     new Intl.ListFormat('en-GB', { type: 'conjunction' }).format(labels);
@@ -56,7 +56,7 @@ export const ABOUT_WARNING_CODES: ReadonlySet<string> = new Set([
 
 type CaptionPart = {
     variableText: string | null;
-    spec: unknown;
+    spec: SpecReading | null;
     warnings?: Pick<Warning, 'code' | 'message' | 'params'>[];
 };
 
@@ -225,10 +225,14 @@ export function noDataCardParts<T extends { index: number; part: unknown }>(
  *  alternate callout, the nearest_real cards, a picker, and every other
  *  status offer no Studio of their own. */
 export function offersStudioCallout(part: unknown, question?: string | null): boolean {
+    const noDataPart = part as Partial<
+        Pick<NoDataPart, 'status' | 'no_data' | 'variable_text'>
+    > | null;
+
     return (
-        (part as { status?: string } | null)?.status === 'no_data' &&
+        noDataPart?.status === 'no_data' &&
         !offersAmbiguousPicker(part) &&
-        noDataCallout(part, question)?.kind === 'studio'
+        noDataCallout(noDataPart, question)?.kind === 'studio'
     );
 }
 
diff --git a/src/lib/search/searchClient.ts b/src/lib/search/searchClient.ts
index 6c53cb8..f456dc9 100644
--- a/src/lib/search/searchClient.ts
+++ b/src/lib/search/searchClient.ts
@@ -377,7 +377,7 @@ export function unflattenSpec(spec: Spec): {
 /** A spec's own rendered sentence + plan, when the engine computed one.
  * Null when neither is set — a spec with no sentence data at all. */
 export const sentenceOf = (
-    spec: any,
+    spec: Pick<Spec, 'rendered_sentence' | 'sentence_plan'> | null | undefined,
 ): { rendered_sentence: string; sentence_plan: SentenceToken[] } | null =>
     spec?.rendered_sentence || spec?.sentence_plan
         ? {
@@ -564,7 +564,7 @@ export function applyDoneEvent(
  * `candidates.specs`, or `no_data.nearest_real`/`no_data.flagged_match`/
  * `no_data.alternate_match`) into the page's flat Spec shape; every other
  * field rides through untouched. */
-function flattenPart(part: any): any {
+function flattenPart(part: any): Part {
     if (!part || typeof part !== 'object') return part;
     // The page Part's restatement, operations, warnings and departures are
     // required, on a part of any status; the wire's are optional. Default
diff --git a/src/lib/search/test/fixtures/partial.ts b/src/lib/search/test/fixtures/partial.ts
new file mode 100644
index 0000000..188bdd0
--- /dev/null
+++ b/src/lib/search/test/fixtures/partial.ts
@@ -0,0 +1,23 @@
+/**
+ * Hand-written fixtures that hold only the members a test reads. Each member may be left out at any
+ * depth (a `resolution` with only `resolved_sources`), and every member a fixture names keeps its
+ * wire name and type.
+ */
+
+import type { Slot, Spec, SpecReading } from '../../types.ts';
+
+/** `T` with every member optional, at every depth. */
+export type DeepPartial<T> = unknown extends T
+    ? T
+    : T extends string | number | boolean | null | undefined
+      ? T
+      : T extends readonly (infer U)[]
+        ? DeepPartial<U>[]
+        : { [K in keyof T]?: DeepPartial<T[K]> };
+
+/** A partial readable spec fixture, as the view helpers read a spec. An unreadable fixture is
+ * typed as `UnreadableSpec` directly, so its raw `stat_vars` never passes as readable. */
+export const partialSpec = (fixture: DeepPartial<Spec>): SpecReading => fixture as SpecReading;
+
+/** A partial slot fixture. */
+export const partialSlot = (fixture: DeepPartial<Slot>): Slot => fixture as Slot;
diff --git a/src/lib/search/test/fixtures/served-answer.ts b/src/lib/search/test/fixtures/served-answer.ts
index a1168a3..058ac3a 100644
--- a/src/lib/search/test/fixtures/served-answer.ts
+++ b/src/lib/search/test/fixtures/served-answer.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the raw wire fixtures */
 /**
  * A served-options fixture (served-options.ts) as the page holds it: the
  * envelope's plan, the definite parts with their flattened specs, and the
@@ -8,7 +7,7 @@
 
 import { keyRef } from '../../searchClient.ts';
 import type { RefinePart } from '../../refineMenu.ts';
-import type { SentenceToken } from '../../types.ts';
+import { knownPart, type SentenceToken, type SlotOptions } from '../../types.ts';
 import { mergeSlotOptionsEntry, type SlotOptionsEntry } from '../../view.ts';
 import { resolution } from './resolution.ts';
 
@@ -21,16 +20,19 @@ export type ServedAnswer = {
 
 export function servedAnswer(body: unknown, events: unknown = []): ServedAnswer {
     const response = resolution(body);
-    const parts: RefinePart[] = response.parts.flatMap((part: any, index: number) =>
-        part.status === 'definite'
-            ? [{ index, variableText: part.variable_text ?? null, spec: part.spec }]
-            : [],
-    );
-    const entries = [
+    const parts: RefinePart[] = response.parts.flatMap((part, index) => {
+        const known = knownPart(part);
+
+        return known?.status === 'definite'
+            ? [{ index, variableText: known.variable_text ?? null, spec: known.spec }]
+            : [];
+    });
+    // The trailing `slot_options` events carry the response's entry shape with the spec_id.
+    const entries: (SlotOptions & { spec_id: string })[] = [
         ...parts.flatMap(({ spec }) =>
-            (spec.slot_options ?? []).map((entry: any) => ({ spec_id: spec.spec_id, ...entry })),
+            (spec.slot_options ?? []).map((entry) => ({ spec_id: spec.spec_id, ...entry })),
         ),
-        ...(events as any[]),
+        ...(events as (SlotOptions & { spec_id: string })[]),
     ];
     const optionsBySpec = entries.reduce(
         (bySpec, entry) =>
diff --git a/src/lib/search/test/origin.test.ts b/src/lib/search/test/origin.test.ts
index 4d1cd76..4b34cda 100644
--- a/src/lib/search/test/origin.test.ts
+++ b/src/lib/search/test/origin.test.ts
@@ -10,6 +10,7 @@ import {
     sourceOrigin,
     specOrigin,
 } from '../view.ts';
+import { partialSpec } from './fixtures/partial.ts';
 
 // The three Data Commons as the engine names them (dfo-apis
 // origin_catalogue.origins).
@@ -117,20 +118,21 @@ const sentenced = (
         resolved = [] as ProvenanceRef[],
         sourceText = 'X',
     } = {},
-) => ({
-    shape: shape({
-        data_commons: [upstream.data_commons!],
-        upstream: { source: upstream.source!, data_commons: upstream.data_commons! },
-    }),
-    slots: [{ key: { axis: 'source', property: null, label: 'source' }, binding }],
-    resolution: { resolved_sources: resolved },
-    sentence_plan: [
-        { kind: 'slot', text: 'Literacy rate', axis: 'what' },
-        { kind: 'text', text: ', according to ' },
-        { kind: 'slot', text: sourceText, axis: 'source' },
-        { kind: 'text', text: '.' },
-    ],
-});
+) =>
+    partialSpec({
+        shape: shape({
+            data_commons: [upstream.data_commons!],
+            upstream: { source: upstream.source!, data_commons: upstream.data_commons! },
+        }),
+        slots: [{ key: { axis: 'source', property: null, label: 'source' }, binding }],
+        resolution: { resolved_sources: resolved },
+        sentence_plan: [
+            { kind: 'slot', text: 'Literacy rate', axis: 'what' },
+            { kind: 'text', text: ', according to ' },
+            { kind: 'slot', text: sourceText, axis: 'source' },
+            { kind: 'text', text: '.' },
+        ],
+    });
 
 test('specOrigin drops the publisher that the sentence already names as its resolved source', () => {
     assert.equal(
@@ -175,7 +177,7 @@ test('specOrigin keeps the publisher when the sentence names a Dataset under it,
 });
 
 test('sourceOrigin finds a picker option by dcid in the trace, the resolved facet or a series', () => {
-    const spec = {
+    const spec = partialSpec({
         resolution: { resolved_sources: [crs] },
         facets: {
             provenance: {
@@ -187,7 +189,7 @@ test('sourceOrigin finds a picker option by dcid in the trace, the resolved face
             },
         },
         observations: { series: [{ source_refs: [sdg] }] },
-    };
+    });
 
     assert.equal(
         sourceOrigin(spec, crs.ref),
@@ -200,7 +202,9 @@ test('sourceOrigin finds a picker option by dcid in the trace, the resolved face
 
 test('the why summary notes each resolved source with its origin and the route of its document', () => {
     const unlinked = { ref: 'dc/base/Unlisted', label: 'dc/base/Unlisted' };
-    const summary = buildWhySummary({ resolution: { resolved_sources: [wdi, crs, unlinked] } });
+    const summary = buildWhySummary(
+        partialSpec({ resolution: { resolved_sources: [wdi, crs, unlinked] } }),
+    );
 
     assert.deepEqual(
         summary.sources.map((source) => [source.ref, source.origin, source.documentation]),
@@ -217,24 +221,28 @@ test('the why summary notes each resolved source with its origin and the route o
 });
 
 test('flattenRows reads the row entity and unit from the series role tuple and facet map', () => {
-    const rows = flattenRows({
-        slots: [],
-        observations: {
-            series: [
-                {
-                    stat_var: { ref: 'Count_Person' },
-                    entities: [{ role: 'observationAbout', ref: 'country/KEN', label: 'Kenya' }],
-                    points: [{ date: '2020', value: 53771300 }],
-                    total_obs: 1,
-                    source_refs: [wdi],
-                    facet: {
-                        provenance: { ref: wdi.ref, label: wdi.label, source: wdi.source },
-                        unit: { ref: 'Percent', label: 'Percent' },
+    const rows = flattenRows(
+        partialSpec({
+            slots: [],
+            observations: {
+                series: [
+                    {
+                        stat_var: { ref: 'Count_Person' },
+                        entities: [
+                            { role: 'observationAbout', ref: 'country/KEN', label: 'Kenya' },
+                        ],
+                        points: [{ date: '2020', value: 53771300 }],
+                        total_obs: 1,
+                        source_refs: [wdi],
+                        facet: {
+                            provenance: { ref: wdi.ref, label: wdi.label, source: wdi.source },
+                            unit: { ref: 'Percent', label: 'Percent' },
+                        },
                     },
-                },
-            ],
-        },
-    });
+                ],
+            },
+        }),
+    );
 
     assert.deepEqual(
         rows.map((row) => [row.year, row.cells['entity:observationAbout'], row.unit]),
diff --git a/src/lib/search/test/previewColumns.test.ts b/src/lib/search/test/previewColumns.test.ts
index 2030f5e..bd5c82e 100644
--- a/src/lib/search/test/previewColumns.test.ts
+++ b/src/lib/search/test/previewColumns.test.ts
@@ -1,4 +1,4 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the flattened wire Spec */
+/* eslint-disable @typescript-eslint/no-explicit-any -- edits a trimmed Kenya spec fixture in place, a deliberately partial spec */
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
diff --git a/src/lib/search/test/refineMenu.test.ts b/src/lib/search/test/refineMenu.test.ts
index 044901c..88813d5 100644
--- a/src/lib/search/test/refineMenu.test.ts
+++ b/src/lib/search/test/refineMenu.test.ts
@@ -2,7 +2,7 @@ import assert from 'node:assert/strict';
 import test from 'node:test';
 
 import { refineItems, refineKey, type RefineItem } from '../refineMenu.ts';
-import type { SentenceToken } from '../types.ts';
+import type { PartSpec, SentenceToken } from '../types.ts';
 import type { EntityOptionsBySpec } from '../view.ts';
 import { servedAnswer, type ServedAnswer } from './fixtures/served-answer.ts';
 import {
@@ -17,6 +17,7 @@ import {
     servedMulti,
 } from './fixtures/served-options.ts';
 import { methodUnbound } from './fixtures/method-unbound.ts';
+import { partialSpec } from './fixtures/partial.ts';
 
 const refineOf = (answer: ServedAnswer, entityOptionsBySpec: EntityOptionsBySpec = {}) =>
     refineItems({ ...answer, entityOptionsBySpec });
@@ -127,7 +128,8 @@ test('refineItems lists a bound binding no token states with its current value,
 
 test('refineItems lists a slot bound to a set whose options are that set, since one member narrows it', () => {
     const member = (dcid: string) => ({ value_kind: 'entity', ref: { ref: dcid, label: dcid } });
-    const spec = {
+    // A Refine part's spec has a spec_id, which partialSpec leaves optional; the fixture names one.
+    const spec = partialSpec({
         spec_id: 'sex-set',
         slots: [
             {
@@ -135,7 +137,7 @@ test('refineItems lists a slot bound to a set whose options are that set, since
                 binding: { kind: 'set', values: [member('Female'), member('Male')] },
             },
         ],
-    };
+    }) as PartSpec;
     const options = [member('Female'), member('Male')].map((value) => ({ value }));
 
     assert.deepEqual(
diff --git a/src/lib/search/test/resultNotes.test.ts b/src/lib/search/test/resultNotes.test.ts
index 5e52216..ba5cfe7 100644
--- a/src/lib/search/test/resultNotes.test.ts
+++ b/src/lib/search/test/resultNotes.test.ts
@@ -21,7 +21,9 @@ import {
     odaToCongoNoData,
     odaToCongoRestatement,
 } from './fixtures/ambiguous-congo.ts';
-import type { Assumption, Warning } from '../types.ts';
+import type { MeasureMenuSpec } from '../measureMenu.ts';
+import type { Assumption, Spec, Warning } from '../types.ts';
+import { type DeepPartial, partialSpec } from './fixtures/partial.ts';
 
 // ---------------------------------------------------------------------------
 // The warning lines the page draws, by place
@@ -29,7 +31,7 @@ import type { Assumption, Warning } from '../types.ts';
 
 // Humanitarian aid from Germany on the dev API, with observations: three
 // warnings and the 20-series preview cap.
-const humanitarianSpec = {
+const humanitarianFixture: DeepPartial<Spec> = {
     spec_id: 'spec_880',
     slots: [],
     headline: {
@@ -49,8 +51,11 @@ const humanitarianSpec = {
             { label: 'variables', count: 39 },
         ],
     },
-    observations: { series: Array.from({ length: 20 }, (_, index) => ({ index })) },
+    observations: {
+        series: Array.from({ length: 20 }, (_, index) => ({ stat_var: { ref: `sv/${index}` } })),
+    },
 };
+const humanitarianSpec = partialSpec(humanitarianFixture);
 const humanitarianWarnings: Warning[] = [
     {
         code: 'retrieval_score_weak',
@@ -103,14 +108,15 @@ const unSystemWarning = (variableLabels: string[]): Warning => ({
 });
 
 test('aboutAnswerNotes holds the coverage sentence and assumptions -- humanitarian aid from Germany', () => {
-    const spec = {
-        ...humanitarianSpec,
+    // aboutAnswerNotes takes a spec_id, which partialSpec leaves optional; the fixture names one.
+    const spec = partialSpec({
+        ...humanitarianFixture,
         resolution: {
             slot_filters: [
                 { key: { axis: 'how', property: { ref: 'crsTypeOfFlow' }, label: 'Type of flow' } },
             ],
         },
-    };
+    }) as MeasureMenuSpec;
 
     assert.deepEqual(aboutAnswerNotes(spec, humanitarianWarnings, {}, humanitarianAssumptions), {
         coverage:
@@ -144,7 +150,13 @@ for (const [name, labels, line] of [
 ] as const) {
     test(`aboutAnswerNotes names the failed UN reads ${name}, and leaves the refused places to the departure`, () => {
         assert.deepEqual(
-            aboutAnswerNotes(humanitarianSpec, [unSystemWarning([...labels])], {}).unavailable,
+            // aboutAnswerNotes takes a spec_id, which partialSpec leaves optional; the fixture
+            // names one.
+            aboutAnswerNotes(
+                humanitarianSpec as MeasureMenuSpec,
+                [unSystemWarning([...labels])],
+                {},
+            ).unavailable,
             [line],
         );
     });
@@ -482,7 +494,9 @@ test('tableCaptionNotes adds the do-not-sum line only when the table marks a tot
     });
     const part = (kinds: [string, string][]) => ({
         variableText: 'aid',
-        spec: { observations: { series: kinds.map(([ref, kind]) => series(ref, kind)) } },
+        spec: partialSpec({
+            observations: { series: kinds.map(([ref, kind]) => series(ref, kind)) },
+        }),
     });
 
     assert.deepEqual(
diff --git a/src/lib/search/test/tokenAbout.test.ts b/src/lib/search/test/tokenAbout.test.ts
index adcf2b5..e6a09a4 100644
--- a/src/lib/search/test/tokenAbout.test.ts
+++ b/src/lib/search/test/tokenAbout.test.ts
@@ -9,9 +9,10 @@ import {
     tokenAbout,
 } from '../tokenAbout.ts';
 import { priceBasis } from '../unitLabel.ts';
-import type { SentenceToken } from '../types.ts';
+import type { SentenceToken, Spec } from '../types.ts';
 import { definite, resolution } from './fixtures/resolution.ts';
 import { fixtures } from './fixtures/index.ts';
+import { type DeepPartial, partialSpec } from './fixtures/partial.ts';
 
 const slot = (fields: Partial<SentenceToken>): SentenceToken => ({
     kind: 'slot',
@@ -31,7 +32,7 @@ const crsProvenance = {
 };
 
 // crs-001's measure: gross ODA disbursements over 152 StatVars, nominal.
-const grossOda = {
+const grossOdaFixture: DeepPartial<Spec> = {
     measure_label: 'gross ODA disbursements',
     measure_axis_values: [
         { axis: 'nettingBasis', value: { ref: 'Gross', label: 'gross' } },
@@ -51,6 +52,7 @@ const grossOda = {
     },
     resolution: { resolved_sources: [crsProvenance] },
 };
+const grossOda = partialSpec(grossOdaFixture);
 
 test('a measure states its unit, span and download rows, and defines the axis values no other token states', () => {
     const measure = slot({ axis: 'what', text: 'Gross ODA disbursements' });
@@ -76,7 +78,7 @@ test('a measure states its unit, span and download rows, and defines the axis va
 // "aid from Germany to Guatemala": 279 series over three varying CRS axes,
 // one of them named by no slot.
 test('the line counts the rows and the note names the axes the series vary on', () => {
-    const spec = {
+    const aidFixture: DeepPartial<Spec> = {
         slots: [
             { key: { axis: 'how', property: { ref: 'crsPurpose' }, label: 'sector' } },
             { key: { axis: 'how', property: { ref: 'crsTypeOfFinance' }, label: 'instrument' } },
@@ -96,6 +98,7 @@ test('the line counts the rows and the note names the axes the series vary on',
         coverage: { dimensions: [{ label: 'variables', count: 279 }] },
         download: { rows: 1284, rows_exact: false },
     };
+    const spec = partialSpec(aidFixture);
     const about = tokenAbout(slot({ axis: 'what', text: 'aid' }), spec);
 
     assert.deepEqual(about.facts, ['up to 1,284 rows']);
@@ -103,14 +106,19 @@ test('the line counts the rows and the note names the axes the series vary on',
         'One series for each sector, instrument and cooperation modality combination.',
     ]);
     assert.equal(
-        seriesReason({ ...spec, open_axis_facts: spec.open_axis_facts.slice(0, 1) }),
+        seriesReason(
+            partialSpec({
+                ...aidFixture,
+                open_axis_facts: aidFixture.open_axis_facts?.slice(0, 1),
+            }),
+        ),
         'One series for each sector.',
     );
     assert.equal(seriesReason({}), null);
 });
 
 test('a measure serving one StatVar reads it from the members door; several read nothing', () => {
-    const one = { spec_id: 'spec_1', stat_vars: { member_count: 3, served_count: 1 } };
+    const one = partialSpec({ spec_id: 'spec_1', stat_vars: { member_count: 3, served_count: 1 } });
     const about = tokenAbout(slot({ axis: 'what', text: 'inflation' }), one);
 
     assert.equal(singleStatVarSpec(one), one);
@@ -210,10 +218,13 @@ test('a group whose node is neither a continent nor a UN subregion keeps the gro
 });
 
 test('an open role counts the members with data', () => {
-    const about = tokenAbout(slot({ role: 'origin', text: '81 donors', binding_ref: 'origin:' }), {
-        entities: [{ ref: 'country/BGD', role: 'destination' }],
-        coverage: { dimensions: [{ label: 'providers', count: 81 }] },
-    });
+    const about = tokenAbout(
+        slot({ role: 'origin', text: '81 donors', binding_ref: 'origin:' }),
+        partialSpec({
+            entities: [{ ref: 'country/BGD', role: 'destination' }],
+            coverage: { dimensions: [{ label: 'providers', count: 81 }] },
+        }),
+    );
 
     assert.equal(about.title, '81 donors');
     assert.deepEqual(about.facts, ['Every provider with data']);
@@ -221,10 +232,13 @@ test('an open role counts the members with data', () => {
 });
 
 test('an open role whose title states no count keeps the count in its fact', () => {
-    const about = tokenAbout(slot({ role: 'origin', text: '', binding_ref: 'origin:' }), {
-        entities: [{ ref: 'country/BGD', role: 'destination' }],
-        coverage: { dimensions: [{ label: 'providers', count: 1234 }] },
-    });
+    const about = tokenAbout(
+        slot({ role: 'origin', text: '', binding_ref: 'origin:' }),
+        partialSpec({
+            entities: [{ ref: 'country/BGD', role: 'destination' }],
+            coverage: { dimensions: [{ label: 'providers', count: 1234 }] },
+        }),
+    );
 
     assert.equal(about.title, 'Any provider');
     assert.deepEqual(about.facts, ['Every provider with data: 1,234 providers']);
@@ -260,7 +274,7 @@ test("one place names itself and its type, and a subject place reads the spec's
 });
 
 test('a period states the served span when it differs, and the latest date with a value', () => {
-    const spec = {
+    const spec = partialSpec({
         coverage: { window: { start_year: 2010, end_year: 2023 } },
         observations: {
             series: [
@@ -273,7 +287,7 @@ test('a period states the served span when it differs, and the latest date with
                 { points: [{ date: '2021', value: 2 }] },
             ],
         },
-    };
+    });
 
     assert.deepEqual(tokenAbout(slot({ axis: 'when', text: 'since 2000' }), spec).facts, [
         'Data served: 2010 to 2023',
@@ -285,7 +299,9 @@ test('a period states the served span when it differs, and the latest date with
 });
 
 test("the served span and latest date fall back to the StatVars' range when nothing else says", () => {
-    const spec = { stat_vars: { data_date_range: { start: '1985-06', end: '2022-12' } } };
+    const spec = partialSpec({
+        stat_vars: { data_date_range: { start: '1985-06', end: '2022-12' } },
+    });
 
     assert.equal(servedSpan(spec), '1985 to 2022');
     assert.equal(latestDate(spec), '2022-12');
@@ -293,10 +309,10 @@ test("the served span and latest date fall back to the StatVars' range when noth
 
 test("the latest date reads the StatVars' range past a preview that stops short", () => {
     // Germany to Kenya: 486 series end in 2024, the 20 previewed end in 2023.
-    const spec = {
+    const spec = partialSpec({
         stat_vars: { data_date_range: { start: '1973', end: '2024' } },
         observations: { series: [{ points: [{ date: '2023', value: 5 }] }] },
-    };
+    });
 
     assert.equal(latestDate(spec), '2024');
 });
@@ -307,7 +323,7 @@ test('a how code defines its bound value, labelling each when there are several'
     };
     const one = tokenAbout(
         slot({ axis: 'how', text: 'for malaria control', binding_ref: 'how:crsPurpose' }),
-        {
+        partialSpec({
             slots: [
                 {
                     ...purpose,
@@ -317,7 +333,7 @@ test('a how code defines its bound value, labelling each when there are several'
                     },
                 },
             ],
-        },
+        }),
     );
 
     assert.equal(one.kind, 'code');
@@ -326,7 +342,7 @@ test('a how code defines its bound value, labelling each when there are several'
 
     const two = tokenAbout(
         slot({ axis: 'how', text: 'for health', binding_ref: 'how:crsPurpose' }),
-        {
+        partialSpec({
             slots: [
                 {
                     ...purpose,
@@ -339,7 +355,7 @@ test('a how code defines its bound value, labelling each when there are several'
                     },
                 },
             ],
-        },
+        }),
     );
 
     assert.deepEqual(two.definitions, [
@@ -393,7 +409,7 @@ test('a unit states its currency, and notes its price basis and the conversion t
     };
     const about = tokenAbout(
         slot({ axis: 'unit', text: 'constant 2022 Kenyan shillings', segment: 'byline' }),
-        {
+        partialSpec({
             identity: {
                 facets: {
                     unit: {
@@ -409,7 +425,7 @@ test('a unit states its currency, and notes its price basis and the conversion t
                 default_base_year: 2024,
                 role_currencies: {},
             },
-        },
+        }),
     );
 
     assert.equal(about.kind, 'unit');
@@ -425,8 +441,8 @@ test('a unit states its currency, and notes its price basis and the conversion t
 test('a source names each provenance with its publisher, taking it from the resolved ref', () => {
     const about = tokenAbout(
         slot({ axis: 'source', text: 'OECD Creditor Reporting System (CRS)', segment: 'byline' }),
-        {
-            ...grossOda,
+        partialSpec({
+            ...grossOdaFixture,
             slots: [
                 {
                     key: { axis: 'source' },
@@ -436,7 +452,7 @@ test('a source names each provenance with its publisher, taking it from the reso
                     },
                 },
             ],
-        },
+        }),
     );
 
     assert.equal(about.kind, 'source');
diff --git a/src/lib/search/test/unitLabel.test.ts b/src/lib/search/test/unitLabel.test.ts
index 889e698..8ea7741 100644
--- a/src/lib/search/test/unitLabel.test.ts
+++ b/src/lib/search/test/unitLabel.test.ts
@@ -1,34 +1,34 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the flattened wire Spec */
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
-import { normalizeResponse } from '../searchClient.ts';
-import type { SentenceToken } from '../types.ts';
-import { unitWithBasis } from '../unitLabel.ts';
+import type { Spec } from '../types.ts';
+import { unitRequest, unitWithBasis } from '../unitLabel.ts';
 import { detailRows, flattenRows } from '../view.ts';
+import { partialSpec } from './fixtures/partial.ts';
+import { definite, readable, resolution } from './fixtures/resolution.ts';
 import { unitAid, unitAidEuroConstant, unitHealth } from './fixtures/unit-conversion.ts';
 
-const envelopeOf = (body: unknown): any => normalizeResponse(body);
-const specOf = (body: unknown): any => envelopeOf(body).parts[0].spec;
+const specOf = (body: unknown) => readable(definite(resolution(body).parts[0]).spec);
 const bylineUnit = (body: unknown): string | undefined =>
-    envelopeOf(body).sentence_plan.find(
-        (token: SentenceToken) => token.axis === 'unit' && token.segment === 'byline',
+    resolution(body).sentence_plan?.find(
+        (token) => token.axis === 'unit' && token.segment === 'byline',
     )?.text;
 
 const conversion = { recipe_id: 'r', exchange_rate_table_version: '1' };
 
-const withSeries = (spec: any, unit: unknown, converted = true): any => ({
-    ...spec,
-    observations: {
-        series: [
-            {
-                points: [{ date: '2020', value: 1 }],
-                facet: unit ? { unit } : {},
-                ...(converted ? { conversion } : {}),
-            },
-        ],
-    },
-});
+const withSeries = (spec: Spec, unit: unknown, converted = true) =>
+    partialSpec({
+        ...spec,
+        observations: {
+            series: [
+                {
+                    points: [{ date: '2020', value: 1 }],
+                    facet: unit ? { unit } : {},
+                    ...(converted ? { conversion } : {}),
+                },
+            ],
+        },
+    });
 
 for (const [name, body, text] of [
     ['native', unitAid, 'Current US dollars'],
@@ -44,7 +44,7 @@ for (const [name, body, text] of [
             [{ label: 'Unit', value: text }],
         );
         assert.deepEqual(
-            flattenRows(withSeries(spec, spec.facets.unit)).map((row) => row.unit),
+            flattenRows(withSeries(spec, spec.facets?.unit)).map((row) => row.unit),
             [text],
         );
     });
@@ -64,7 +64,7 @@ test('the byline unit token on the spec wins over the composed text', () => {
 test('a preview with no conversion record keeps the series unit although the identity asks for one', () => {
     const spec = specOf(unitAidEuroConstant);
 
-    assert.equal(spec.identity.facets.unit.request.prices, 'constant');
+    assert.equal(unitRequest(spec)?.prices, 'constant');
     assert.deepEqual(
         flattenRows(withSeries(spec, { ref: 'CurrencyUSD', label: 'US Dollar' }, false)).map(
             (row) => row.unit,
diff --git a/src/lib/search/test/unitPicker.test.ts b/src/lib/search/test/unitPicker.test.ts
index 336906e..e78c004 100644
--- a/src/lib/search/test/unitPicker.test.ts
+++ b/src/lib/search/test/unitPicker.test.ts
@@ -1,10 +1,9 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the flattened wire Spec */
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
 import { buildDatasetEntries } from '../datasetEntries.ts';
 import { currencyName } from '../tokenAbout.ts';
-import type { HydratedPart, UnitConversion } from '../types.ts';
+import { type HydratedPart, knownPart, type UnitConversion } from '../types.ts';
 import {
     currencyMatches,
     currencyRequest,
@@ -26,17 +25,18 @@ import {
     unitDebt,
     unitHealth,
 } from './fixtures/unit-conversion.ts';
-import { definite, resolution } from './fixtures/resolution.ts';
+import { partialSpec } from './fixtures/partial.ts';
+import { definite, readable, resolution } from './fixtures/resolution.ts';
 
-const specOf = (body: unknown): any => definite(resolution(body).parts[0]).spec;
+const specOf = (body: unknown) => readable(definite(resolution(body).parts[0]).spec);
 
 /** `body`'s parts as the page hydrates them, each spec as served. */
 const hydratedParts = (body: unknown): HydratedPart[] =>
-    resolution(body).parts.map((part: any, index: number) => ({
+    resolution(body).parts.map((part, index) => ({
         index,
         variableText: part.variable_text ?? null,
         part,
-        hydratedSpec: part.spec ?? null,
+        hydratedSpec: knownPart(part)?.status === 'definite' ? definite(part).spec : null,
         observationsPending: false,
         phase: 'done',
         editError: null,
@@ -77,7 +77,7 @@ test('unitPresets names role currencies by their entity and dedupes by code', ()
 });
 
 test("unitPresets keeps a row for the answer's own currency", () => {
-    const yen = {
+    const yen = partialSpec({
         ...aidEuroConstant,
         identity: {
             ...aidEuroConstant.identity,
@@ -88,7 +88,7 @@ test("unitPresets keeps a row for the answer's own currency", () => {
                 },
             },
         },
-    };
+    });
 
     assert.deepEqual(unitPresets(yen, unitConversion(yen)).at(-1), {
         code: 'JPY',
@@ -99,7 +99,7 @@ test("unitPresets keeps a row for the answer's own currency", () => {
 });
 
 test('unitPresets falls back to the role request when the role names no single entity', () => {
-    const spec = { ...aid, entities: aid.entities.filter((e: any) => e.role !== 'destination') };
+    const spec = { ...aid, entities: (aid.entities ?? []).filter((e) => e.role !== 'destination') };
     const recipient = unitPresets(spec, unitConversion(spec)).find(
         (preset) => preset.code === 'GTQ',
     );
@@ -294,20 +294,22 @@ test('a currency with no current-price years offers constant prices alone', () =
 });
 
 test('a pick on the shared unit token applies to every part that converts', () => {
-    const body: any = unitAidLoans;
-    const unitTokens = body.sentence_plan.filter((token: any) => token.axis === 'unit');
+    const body = resolution(unitAidLoans);
+    const unitTokens = (body.sentence_plan ?? []).filter((token) => token.axis === 'unit');
 
     // The fixture's premise: one hoisted unit token over two convertible parts.
     assert.deepEqual(
-        unitTokens.map((token: any) => token.part_index ?? null),
+        unitTokens.map((token) => token.part_index ?? null),
         [null],
     );
 
-    const parts = hydratedParts(body);
+    const parts = hydratedParts(unitAidLoans);
     const request = { currency: 'EUR', prices: 'constant', base_year: 2020 } as const;
     const edit = sharedUnitEdit(parts, request)!;
     const units = (rows: HydratedPart[], override = edit.override) =>
-        buildDatasetEntries(rows, override).map((entry: any) => entry.identity.facets?.unit);
+        buildDatasetEntries(rows, override).map((entry) =>
+            entry.entry_kind === 'identity' ? entry.identity.facets?.unit : undefined,
+        );
 
     assert.deepEqual(edit.touched, [0, 1]);
     assert.deepEqual(units(parts), [
diff --git a/src/lib/search/test/view.test.ts b/src/lib/search/test/view.test.ts
index 07e8fcf..b6ab2fe 100644
--- a/src/lib/search/test/view.test.ts
+++ b/src/lib/search/test/view.test.ts
@@ -51,8 +51,9 @@ import {
     splitCurrentPick,
 } from '../view.ts';
 import type { EntityOptionsBySpec, PlaceOptionScopeResult, PlaceOptionsEntry } from '../view.ts';
-import type { SentenceToken, Slot, SlotOption } from '../types.ts';
+import type { SentenceToken, Slot, SlotOption, Spec } from '../types.ts';
 import type { EntityOption } from '../searchClient.ts';
+import { type DeepPartial, partialSlot, partialSpec } from './fixtures/partial.ts';
 
 /** A slot option binding `ref`, or the one that binds no value. */
 const slotOption = (ref?: string, label = ref): SlotOption => ({
@@ -318,7 +319,7 @@ test('coverageSentence names the scope of every count, with singular nouns for o
         role_counts: { financingProvider: provider, financingRecipient: recipient },
     });
     const dimensions = (recipients: number) => ({
-        kind: 'breadth',
+        kind: 'breadth' as const,
         dimensions: [
             { label: 'recipients', count: recipients },
             { label: 'variables', count: 39 },
@@ -326,27 +327,43 @@ test('coverageSentence names the scope of every count, with singular nouns for o
     });
     const cases = [
         {
-            spec: { headline: latest(155, 1, 61), entities: germany, coverage: dimensions(145) },
+            spec: partialSpec({
+                headline: latest(155, 1, 61),
+                entities: germany,
+                coverage: dimensions(145),
+            }),
             sentence:
                 '2024 is the latest year with data, with 155 values for 61 of the 145 recipients that have data from Germany.',
         },
         {
-            spec: { headline: latest(157, 34, 1), entities: nigeria, coverage: { dimensions: [] } },
+            spec: partialSpec({
+                headline: latest(157, 34, 1),
+                entities: nigeria,
+                coverage: { dimensions: [] },
+            }),
             sentence:
                 '2024 is the latest year with data, with 157 values from 34 providers to Nigeria.',
         },
         {
-            spec: { headline: latest(5, 4, 2), entities: [], coverage: dimensions(42) },
+            spec: partialSpec({
+                headline: latest(5, 4, 2),
+                entities: [],
+                coverage: dimensions(42),
+            }),
             sentence:
                 '2024 is the latest year with data, with 5 values from 4 providers for 2 of the 42 recipients that have data.',
         },
         {
-            spec: { headline: latest(1, 1, 1), entities: germany, coverage: dimensions(1) },
+            spec: partialSpec({
+                headline: latest(1, 1, 1),
+                entities: germany,
+                coverage: dimensions(1),
+            }),
             sentence:
                 '2024 is the latest year with data, with 1 value for the one recipient that has data from Germany.',
         },
         {
-            spec: {
+            spec: partialSpec({
                 headline: {
                     ...latest(30, 1, 30),
                     year: 2020,
@@ -355,11 +372,11 @@ test('coverageSentence names the scope of every count, with singular nouns for o
                 },
                 entities: germany,
                 coverage: dimensions(30),
-            },
+            }),
             sentence: '2020 has 30 values for all 30 recipients that have data from Germany.',
         },
         {
-            spec: {
+            spec: partialSpec({
                 headline: {
                     ...latest(157, 34, 1),
                     year: 2020,
@@ -368,7 +385,7 @@ test('coverageSentence names the scope of every count, with singular nouns for o
                 },
                 entities: nigeria,
                 coverage: { dimensions: [] },
-            },
+            }),
             sentence:
                 '2020 is the latest year with data in the years asked, with 157 values from 34 providers to Nigeria.',
         },
@@ -378,13 +395,16 @@ test('coverageSentence names the scope of every count, with singular nouns for o
         assert.equal(coverageSentence(spec), sentence);
     }
 
-    assert.equal(coverageSentence({ coverage: dimensions(145) }), null);
+    assert.equal(coverageSentence(partialSpec({ coverage: dimensions(145) })), null);
 });
 
 test('seriesPreviewCaptions counts the series a truncated preview holds, labelled per part', () => {
-    const series = Array.from({ length: 20 }, (_, index) => ({ series_key: String(index) }));
+    const series = Array.from({ length: 20 }, (_, index) => ({ stat_var: { ref: `sv/${index}` } }));
     const truncated = [{ code: 'observations_series_truncated' }];
-    const part = { variableText: 'humanitarian aid', spec: { observations: { series } } };
+    const part = {
+        variableText: 'humanitarian aid',
+        spec: partialSpec({ observations: { series } }),
+    };
 
     assert.deepEqual(seriesPreviewCaptions([{ ...part, warnings: truncated }]), [
         'Showing 20 series, in no particular order',
@@ -423,7 +443,7 @@ test('seriesPreviewCaptions counts the series a truncated preview holds, labelle
     const withOrder = (order: 'ranked' | 'fixed', warningOrder: string) => [
         {
             ...part,
-            spec: { observations: { series, order } },
+            spec: partialSpec({ observations: { series, order } }),
             warnings: [
                 {
                     code: 'observations_series_truncated',
@@ -445,7 +465,7 @@ test('seriesPreviewCaptions counts the series a truncated preview holds, labelle
 
 // ODA from Germany on the local API: the download facts, unit, source and
 // open axes behind the right panel.
-const odaPanelSpec = {
+const odaPanelSpec = partialSpec({
     download: {
         rows: 152601,
         rows_exact: true,
@@ -480,7 +500,7 @@ const odaPanelSpec = {
     ],
     confidence: 'medium',
     coverage: { kind: 'breadth', dimensions: [{ label: 'recipients', count: 191 }] },
-};
+});
 
 test('downloadRowCount reads the rows in the file, an upper bound as up to, and nothing it cannot count', () => {
     assert.deepEqual(downloadRowCount(odaPanelSpec), { rows: 152601, upTo: false });
@@ -490,7 +510,7 @@ test('downloadRowCount reads the rows in the file, an upper bound as up to, and
     });
     assert.equal(downloadRowCount({ download: { rows: null, rows_exact: false } }), null);
     // A breadth answer's one-year count is no stand-in for the file.
-    assert.equal(downloadRowCount({ coverage: { observation_count: 7618 } }), null);
+    assert.equal(downloadRowCount(partialSpec({ coverage: { observation_count: 7618 } })), null);
 });
 
 test('detailRows describes the file: years, series, unit, licence linked to its source, size once measured, and gaps', () => {
@@ -512,7 +532,7 @@ test('detailRows describes the file: years, series, unit, licence linked to its
 });
 
 test('detailRows leaves out what the API did not send, and links no licence for an answer over several sources', () => {
-    const inflation = {
+    const inflation = partialSpec({
         download: {
             rows: 23,
             rows_exact: true,
@@ -521,7 +541,7 @@ test('detailRows leaves out what the API did not send, and links no licence for
             licence: { label: 'PublicDomain' },
         },
         resolution: { resolved_sources: [{ ref: 'a' }, { ref: 'b' }] },
-    };
+    });
 
     assert.deepEqual(detailRows(inflation), [
         { label: 'Years', value: '2000 to 2022' },
@@ -678,7 +698,7 @@ test("mergeSlotOptionsEntry leaves a different spec's entries untouched", () =>
 // --- slotOptionLabel ------------------------------------------------------
 
 test('slotOptionLabel reshapes a source-axis option through sourceOptionLabel (de-camelcased)', () => {
-    const slot = { key: { axis: 'source' } };
+    const slot = partialSlot({ key: { axis: 'source' } });
     const option = {
         value: { ref: { ref: 'WorldDevelopmentIndicators', label: 'WorldDevelopmentIndicators' } },
     };
@@ -687,7 +707,7 @@ test('slotOptionLabel reshapes a source-axis option through sourceOptionLabel (d
 });
 
 test('slotOptionLabel reads the plain optionLabel for a non-source axis', () => {
-    const slot = { key: { axis: 'how' } };
+    const slot = partialSlot({ key: { axis: 'how' } });
     const option = { value: { ref: { ref: 'crsPurpose/110', label: 'Education' } } };
 
     assert.equal(slotOptionLabel(slot, option), 'Education');
@@ -696,7 +716,7 @@ test('slotOptionLabel reads the plain optionLabel for a non-source axis', () =>
 test('slotOptionLabel falls back to optionLabel rather than throwing when the slot has no key at all', () => {
     const option = { value: { ref: { ref: 'crsPurpose/110', label: 'Education' } } };
 
-    assert.equal(slotOptionLabel({}, option), 'Education');
+    assert.equal(slotOptionLabel(partialSlot({}), option), 'Education');
 });
 
 // --- showGroupHeadings ----------------------------------------------------
@@ -1978,7 +1998,7 @@ test('slotOffersChoice offers a value binding its other options, and an unbound
     const aid = servedAnswer(servedAid);
     const choice = ({ parts, optionsBySpec }: typeof aid, ref: string) => {
         const { spec } = parts[0];
-        const slot = spec.slots.find(
+        const slot = (spec.slots ?? []).find(
             (candidate: { key: Parameters<typeof keyRef>[0] }) => keyRef(candidate.key) === ref,
         );
 
@@ -1992,11 +2012,12 @@ test('slotOffersChoice offers a value binding its other options, and an unbound
 
     // An unbound slot with one option narrows only when that option is
     // counted and serves fewer rows than the answer downloads.
-    const unbound = { key: { axis: 'how' }, binding: { kind: 'unbound' } };
-    const spec = {
+    const unbound = partialSlot({ key: { axis: 'how' }, binding: { kind: 'unbound' } });
+    const rowsFixture: DeepPartial<Spec> = {
         coverage: { dimensions: [{ label: 'variables', count: 279 }] },
         download: { rows: 1284, rows_exact: true },
     };
+    const spec = partialSpec(rowsFixture);
     const one = (served_rows: number | null) => ({
         options: [{ ...slotOption('Net'), served_rows }],
         truncated: false,
@@ -2005,15 +2026,23 @@ test('slotOffersChoice offers a value binding its other options, and an unbound
     assert.equal(slotOffersChoice(unbound, one(279), spec), true);
     assert.equal(slotOffersChoice(unbound, one(1284), spec), false);
     assert.equal(slotOffersChoice(unbound, one(null), spec), false);
-    assert.equal(slotOffersChoice(unbound, one(279), { ...spec, download: { rows: null } }), false);
+    assert.equal(
+        slotOffersChoice(
+            unbound,
+            one(279),
+            partialSpec({ ...rowsFixture, download: { rows: null } }),
+        ),
+        false,
+    );
 
     // A slot bound to a set spans its members the way an unbound slot spans
     // every option: two members narrow, as does one counted member that
     // serves fewer rows than the answer. A set of one reads as a value.
-    const set = (...dcids: string[]) => ({
-        key: { axis: 'how' },
-        binding: { kind: 'set', values: dcids.map((dcid) => ({ ref: { ref: dcid } })) },
-    });
+    const set = (...dcids: string[]) =>
+        partialSlot({
+            key: { axis: 'how' },
+            binding: { kind: 'set', values: dcids.map((dcid) => ({ ref: { ref: dcid } })) },
+        });
     const members = (...dcids: string[]) => ({
         options: dcids.map((dcid) => ({ ...slotOption(dcid), served_rows: null })),
         truncated: false,
diff --git a/src/lib/search/test/why.test.ts b/src/lib/search/test/why.test.ts
index 2d23ebd..b15d053 100644
--- a/src/lib/search/test/why.test.ts
+++ b/src/lib/search/test/why.test.ts
@@ -1,12 +1,14 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
-import type { Assumption, Warning } from '../types.ts';
+import { tokenAbout } from '../tokenAbout.ts';
+import type { Assumption, SentenceToken, UnreadableSpec, Warning } from '../types.ts';
 import { buildWhySummary, scopeAssumptions } from '../view.ts';
+import { partialSpec } from './fixtures/partial.ts';
 
 // Trimmed from dev API answers: inflation in Pakistan (one variable) and ODA
 // from Germany (1,626 variables, the recipient role open).
-const inflation = {
+const inflation = partialSpec({
     stat_vars: {
         member_count: 1,
         member_count_exact: false,
@@ -18,7 +20,7 @@ const inflation = {
     facets: { unit: { ref: 'SDG_PERCENT', label: 'Percentage' } },
     coverage: { kind: 'exact', observation_count: 23, dimensions: [] },
     resolution: {},
-};
+});
 
 // The members door's answer for inflation, as definitionMembersReader
 // returns it: its one StatVar.
@@ -36,7 +38,7 @@ const odaMembers = {
     })),
 };
 
-const oda = {
+const oda = partialSpec({
     stat_vars: { member_count: 1626, member_count_exact: true, served_count: 1626 },
     measure_label: 'gross disbursements (nominal)',
     shape: { label: 'gross disbursements (nominal, official development assistance)' },
@@ -52,7 +54,7 @@ const oda = {
         ],
     },
     resolution: {},
-};
+});
 
 const odaWarnings: Warning[] = [
     { code: 'retrieval_score_weak', severity: 'info', message: 'weak' },
@@ -79,6 +81,30 @@ const placeScope = (text: string): Assumption => ({
     text,
 });
 
+test('an unreadable spec counts no StatVars in the measure About or the Why panel', () => {
+    // flattenSpec keeps the stat_vars that failed to read; served_count alone looks valid.
+    const spec: UnreadableSpec = {
+        spec_id: 'spec_unreadable',
+        stat_vars_unreadable: true,
+        stat_vars: { served_count: 3, member_count: '3' },
+        measure_label: 'gross disbursements',
+        open_axis_facts: [
+            { property: 'crsPurpose', varies: true, distinct_count: 3, undeclared_count: 0 },
+        ],
+    };
+    const measure: SentenceToken = {
+        kind: 'slot',
+        axis: 'what',
+        text: 'gross disbursements',
+        segment: 'heading',
+    };
+    const summary = buildWhySummary(spec);
+
+    assert.deepEqual(tokenAbout(measure, spec).notes, []);
+    assert.equal(summary.variables, null);
+    assert.equal(summary.family, null);
+});
+
 test('one variable: the Measure row carries its code and no Variables group appears', () => {
     const part = { warnings: [], variable_text: 'inflation' };
     const summary = buildWhySummary(inflation, part, inflationMembers);
@@ -153,7 +179,11 @@ test('the resolved membership chooses the layout over the coverage variables cou
         unsettled,
         { member_count: 3, member_count_exact: true, served_count: 3 },
     ]) {
-        const summary = buildWhySummary({ ...oda, stat_vars, coverage: variables(1) }, part, three);
+        const summary = buildWhySummary(
+            partialSpec({ ...oda, stat_vars, coverage: variables(1) }),
+            part,
+            three,
+        );
 
         assert.equal(summary.variables?.count, 3);
         assert.equal(summary.variables?.exact, true);
@@ -169,11 +199,11 @@ test('the resolved membership chooses the layout over the coverage variables cou
 
     // Coverage reports three, the members door lists one.
     const single = buildWhySummary(
-        {
+        partialSpec({
             ...oda,
             stat_vars: { member_count: 3, member_count_exact: true, served_count: 1 },
             coverage: variables(3),
-        },
+        }),
         part,
         one,
     );
@@ -188,7 +218,10 @@ test('the resolved membership chooses the layout over the coverage variables cou
 
     // Membership unsettled and the members still being read: the family's
     // floor fills the Variables group, whatever coverage counts.
-    const pending = buildWhySummary({ ...oda, stat_vars: unsettled, coverage: variables(1) }, part);
+    const pending = buildWhySummary(
+        partialSpec({ ...oda, stat_vars: unsettled, coverage: variables(1) }),
+        part,
+    );
 
     assert.equal(pending.variables?.count, 3);
     assert.equal(pending.variables?.exact, false);
@@ -200,47 +233,55 @@ test('many variables: the breakdown counts the variables by each value of an axi
         value: { ref: dcid, label },
         count,
     });
-    const summary = buildWhySummary({
-        ...oda,
-        stat_vars: { member_count: 39, member_count_exact: true, served_count: 39 },
-        slots: [
-            { key: { axis: 'how', property: { ref: 'crsTypeOfFinance' }, label: 'instrument' } },
-        ],
-        open_axis_facts: [
-            {
-                property: 'crsTypeOfFinance',
-                varies: true,
-                distinct_count: 2,
-                undeclared_count: 0,
-                values: [
-                    value('CRSTypeOfFinance110', 'standard grant', 35),
-                    value('CRSTypeOfFinance421', 'standard loan', 4),
-                ],
-            },
-            {
-                property: 'crsCooperationModality',
-                varies: true,
-                distinct_count: 7,
-                undeclared_count: 8,
-                values: [
-                    value('C01', 'project-type intervention', 6),
-                    value('B03', 'contribution to a pooled fund', 5),
-                    value('B01', 'core support to NGOs', 5),
-                    value('H01', 'development awareness', 5),
-                    value('D02', 'other technical assistance', 4),
-                    value('G01', 'administrative costs', 4),
-                    value('E01', 'scholarships', 2),
-                ],
-            },
-            {
-                property: 'crsChannel',
-                varies: false,
-                distinct_count: 1,
-                undeclared_count: 0,
-                values: [value('Channel1', 'public sector', 39)],
-            },
-        ],
-    });
+    const summary = buildWhySummary(
+        partialSpec({
+            ...oda,
+            stat_vars: { member_count: 39, member_count_exact: true, served_count: 39 },
+            slots: [
+                {
+                    key: {
+                        axis: 'how',
+                        property: { ref: 'crsTypeOfFinance' },
+                        label: 'instrument',
+                    },
+                },
+            ],
+            open_axis_facts: [
+                {
+                    property: 'crsTypeOfFinance',
+                    varies: true,
+                    distinct_count: 2,
+                    undeclared_count: 0,
+                    values: [
+                        value('CRSTypeOfFinance110', 'standard grant', 35),
+                        value('CRSTypeOfFinance421', 'standard loan', 4),
+                    ],
+                },
+                {
+                    property: 'crsCooperationModality',
+                    varies: true,
+                    distinct_count: 7,
+                    undeclared_count: 8,
+                    values: [
+                        value('C01', 'project-type intervention', 6),
+                        value('B03', 'contribution to a pooled fund', 5),
+                        value('B01', 'core support to NGOs', 5),
+                        value('H01', 'development awareness', 5),
+                        value('D02', 'other technical assistance', 4),
+                        value('G01', 'administrative costs', 4),
+                        value('E01', 'scholarships', 2),
+                    ],
+                },
+                {
+                    property: 'crsChannel',
+                    varies: false,
+                    distinct_count: 1,
+                    undeclared_count: 0,
+                    values: [value('Channel1', 'public sector', 39)],
+                },
+            ],
+        }),
+    );
 
     assert.deepEqual(summary.variables?.breakdown, [
         {
@@ -271,7 +312,7 @@ test('many variables: the breakdown counts the variables by each value of an axi
 const singleOfFamily = [
     {
         description: 'life expectancy in Ethiopia',
-        spec: {
+        spec: partialSpec({
             stat_vars: {
                 member_count: 3,
                 member_count_exact: false,
@@ -290,7 +331,7 @@ const singleOfFamily = [
                 ],
             },
             headline: null,
-        },
+        }),
         member: { dcid: 'LifeExpectancy_Person', label: 'Life Expectancy' },
         rows: [
             { label: 'Measure', value: 'Life Expectancy', code: 'LifeExpectancy_Person' },
@@ -302,7 +343,7 @@ const singleOfFamily = [
     },
     {
         description: 'GDP of Kenya',
-        spec: {
+        spec: partialSpec({
             stat_vars: {
                 member_count: 38,
                 member_count_exact: false,
@@ -320,7 +361,7 @@ const singleOfFamily = [
                 ],
             },
             headline: null,
-        },
+        }),
         member: {
             dcid: 'Amount_EconomicActivity_GrossDomesticProduction_Nominal',
             label: 'Nominal gross domestic product',
@@ -469,7 +510,7 @@ test('each assumption becomes one sentence, and each scope warning names its row
 });
 
 test('chosen: each facet axis gives its value and why, in source, method, unit order', () => {
-    const spec = {
+    const spec = partialSpec({
         facets: {
             unit: { ref: 'CurrencyUSD', label: 'US Dollar', basis: 'fallback' },
             provenance: {
@@ -479,7 +520,7 @@ test('chosen: each facet axis gives its value and why, in source, method, unit o
             },
             measurementMethod: { selection: 'per_series', basis: 'declared_default' },
         },
-    };
+    });
 
     assert.deepEqual(buildWhySummary(spec).chosen, [
         { label: 'Source', value: 'World Development Indicators', reason: 'Set by your request.' },
@@ -503,7 +544,7 @@ test('a slot a declared default filled is stated once, as an assumption; no prov
         refs: [{ ref, label: ref }],
         provenance,
     });
-    const spec = {
+    const spec = partialSpec({
         resolution: {
             slot_filters: [
                 filter('declared_default', 'type of flow', 'ODA'),
@@ -511,7 +552,7 @@ test('a slot a declared default filled is stated once, as an assumption; no prov
                 filter('measure_elected', 'finance type', 'Grant'),
             ],
         },
-    };
+    });
 
     const defaulted: Assumption = {
         kind: 'declared_default',
@@ -535,15 +576,17 @@ test('sources carry the licence only when the answer serves one source', () => {
     const download = { licence: { label: 'CCBY4' } };
 
     assert.equal(
-        buildWhySummary({ download, resolution: { resolved_sources: [source('a')] } }).sources[0]
-            ?.licence,
+        buildWhySummary(partialSpec({ download, resolution: { resolved_sources: [source('a')] } }))
+            .sources[0]?.licence,
         'CCBY4',
     );
     assert.deepEqual(
-        buildWhySummary({
-            download,
-            resolution: { resolved_sources: [source('a'), source('b')] },
-        }).sources.map((entry) => entry.licence),
+        buildWhySummary(
+            partialSpec({
+                download,
+                resolution: { resolved_sources: [source('a'), source('b')] },
+            }),
+        ).sources.map((entry) => entry.licence),
         [null, null],
     );
 });
diff --git a/src/lib/search/tokenAbout.ts b/src/lib/search/tokenAbout.ts
index 70c9f6d..ad60934 100644
--- a/src/lib/search/tokenAbout.ts
+++ b/src/lib/search/tokenAbout.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads specs as `any`, dereferencing only the members it names and tolerating any that is missing */
 /**
  * The About line at the top of a sentence token's panel: what the token's
  * current value is, read from the Spec the answer already carries. The line
@@ -14,19 +13,24 @@ import { keyRef } from './searchClient.ts';
 import { capitalise } from '../capitalise.ts';
 import {
     type EntityRoleKey,
+    type GraphRef,
     hasKey,
     type Known,
+    type ProvenanceRef,
     type SentenceToken,
+    type SpecReading,
     type UnitConversion,
 } from './types.ts';
 import { priceBasis } from './unitLabel.ts';
 import type { PriceBasis } from './unitLabel.ts';
 import {
     axisLabel,
+    dimensionCount,
     formatCount,
     formatWindow,
     observationSeries,
     provenanceOrigin,
+    readStatVars,
     rowsLabel,
     servedSeriesCount,
     specUnit,
@@ -68,10 +72,6 @@ const typeWords = (type: string): string =>
             .toLowerCase(),
     );
 
-const dimensionCount = (spec: any, label: string): number | null =>
-    (spec?.coverage?.dimensions ?? []).find((dimension: any) => dimension?.label === label)
-        ?.count ?? null;
-
 const yearOf = (date: unknown): string | null =>
     typeof date === 'string' && date.length >= 4 ? date.slice(0, 4) : null;
 
@@ -80,12 +80,12 @@ const span = (start: string | null, end: string | null): string | null =>
 
 /** The years the served data spans: the coverage window, else the Spec's
  *  `stat_vars.data_date_range` over its served StatVars. */
-export const servedSpan = (spec: any): string | null => {
+export const servedSpan = (spec: SpecReading): string | null => {
     const covered = formatWindow(spec?.coverage?.window);
 
     if (covered) return covered;
 
-    const range = spec?.stat_vars?.data_date_range;
+    const range = readStatVars(spec)?.data_date_range;
 
     return span(yearOf(range?.start), yearOf(range?.end));
 };
@@ -94,8 +94,8 @@ export const servedSpan = (spec: any): string | null => {
  *  and the observation points that hold a value. The range spans every
  *  year; the points are a preview of a few series, so they only add a
  *  date when the range is missing or stops short of them. */
-export const latestDate = (spec: any): string | null => {
-    const end: unknown = spec?.stat_vars?.data_date_range?.end;
+export const latestDate = (spec: SpecReading): string | null => {
+    const end: unknown = readStatVars(spec)?.data_date_range?.end;
     const ends: string[] = typeof end === 'string' && end ? [end] : [];
     const points = observationSeries(spec).flatMap((series) =>
         series.points.filter((point) => point.value != null).map((point) => point.date),
@@ -107,10 +107,10 @@ export const latestDate = (spec: any): string | null => {
 /** Why the measure serves several series: the axes on which the served
  *  series differ ("One series for each sector, instrument and modality
  *  combination."). Null when no axis is known to vary. */
-export const seriesReason = (spec: any): string | null => {
+export const seriesReason = (spec: SpecReading): string | null => {
     const axes: string[] = (spec?.open_axis_facts ?? [])
-        .filter((fact: any) => fact?.varies && typeof fact.property === 'string')
-        .map((fact: any) => axisLabel(spec, fact.property));
+        .filter((fact) => fact?.varies && typeof fact.property === 'string')
+        .map((fact) => axisLabel(spec, fact.property));
 
     if (axes.length === 0) return null;
 
@@ -122,15 +122,16 @@ export const seriesReason = (spec: any): string | null => {
 /** The Spec whose members a measure's About reads from the members door
  *  (`useDefinitionMembers`) to define its one StatVar: the Spec itself when
  *  the answer serves one StatVar, else null. */
-export const singleStatVarSpec = (spec: any): any =>
-    spec && servedSeriesCount(spec) === 1 ? spec : null;
+export const singleStatVarSpec = <TSpec extends SpecReading>(
+    spec: TSpec | null | undefined,
+): TSpec | null => (spec && servedSeriesCount(spec) === 1 ? spec : null);
 
 // A measure's About leaves out the axis values another visible token
 // states (`statedElsewhere`, refs such as "axis:measurementQualifier" the
 // unit token states), since that token's own panel describes them.
 const measureAbout = (
     token: SentenceToken,
-    spec: any,
+    spec: SpecReading,
     statedElsewhere: ReadonlySet<string>,
 ): TokenAboutModel => {
     const count = servedSeriesCount(spec);
@@ -141,8 +142,8 @@ const measureAbout = (
     ].filter((fact): fact is string => !!fact);
     const reason = count != null && count > 1 ? seriesReason(spec) : null;
     const values: AboutDefinition[] = (spec?.measure_axis_values ?? [])
-        .filter((entry: any) => entry?.value?.ref && !statedElsewhere.has(`axis:${entry.axis}`))
-        .map((entry: any) => ({
+        .filter((entry) => entry?.value?.ref && !statedElsewhere.has(`axis:${entry.axis}`))
+        .map((entry) => ({
             label: capitalise(entry.value.label ?? entry.value.ref),
             dcid: entry.value.ref,
         }));
@@ -175,11 +176,11 @@ const listNames = (names: string[]): string =>
         ? `${names.slice(0, LISTED_MEMBERS).join(', ')} and ${formatCount(names.length - LISTED_MEMBERS)} more`
         : names.join(', ');
 
-const entityAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
+const entityAbout = (token: SentenceToken, spec: SpecReading): TokenAboutModel => {
     const role: EntityRoleKey = token.role ?? 'observationAbout';
     // A role this release does not know reads as the subject role.
     const nouns = hasKey(ROLE_NOUNS, role) ? ROLE_NOUNS[role] : ROLE_NOUNS.observationAbout;
-    const entities: any[] = spec?.entities ?? [];
+    const entities = spec?.entities ?? [];
     const dcids: string[] = token.entity_refs?.length
         ? token.entity_refs
         : entities.filter((entity) => entity?.role === role).map((entity) => entity.ref);
@@ -211,13 +212,17 @@ const entityAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
 
     const names = dcids.map((dcid) => byDcid.get(dcid)?.label ?? dcid);
     const types = [
-        ...new Set(dcids.map((dcid) => byDcid.get(dcid)?.entity_type).filter(Boolean)),
+        ...new Set(
+            dcids
+                .map((dcid) => byDcid.get(dcid)?.entity_type)
+                .filter((type): type is string => !!type),
+        ),
     ].map(typeWords);
     const typeFact = types.length > 0 ? types.join(', ') : null;
 
     if (group) {
         const count = formatCount(dcids.length);
-        const fact = REGION_GROUP_TYPES.has(group.entity_type)
+        const fact = REGION_GROUP_TYPES.has(group.entity_type ?? '')
             ? `${count} ${dcids.length === 1 ? 'country or territory' : 'countries and territories'}`
             : `Group of ${count} ${dcids.length === 1 ? 'member' : 'members'}${typeFact ? ` (${typeFact.toLowerCase()})` : ''}`;
 
@@ -254,7 +259,7 @@ const entityAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
     };
 };
 
-const periodAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
+const periodAbout = (token: SentenceToken, spec: SpecReading): TokenAboutModel => {
     const title = token.text.trim();
     const served = servedSpan(spec);
     const latest = latestDate(spec);
@@ -272,16 +277,16 @@ const periodAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
     };
 };
 
-const codeAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
-    const slot = (spec?.slots ?? []).find((s: any) => keyRef(s.key) === token.binding_ref);
+const codeAbout = (token: SentenceToken, spec: SpecReading): TokenAboutModel => {
+    const slot = (spec?.slots ?? []).find((s) => keyRef(s.key) === token.binding_ref);
     const binding = slot?.binding;
-    const refs: any[] =
+    const refs: (GraphRef | null | undefined)[] =
         binding?.kind === 'value'
             ? [binding.value?.ref]
             : binding?.kind === 'set'
-              ? (binding.values ?? []).map((value: any) => value?.ref)
+              ? (binding.values ?? []).map((value) => value?.ref)
               : [];
-    const codes = refs.filter((ref) => typeof ref?.ref === 'string');
+    const codes = refs.filter((ref): ref is GraphRef => typeof ref?.ref === 'string');
 
     return {
         kind: 'code',
@@ -317,8 +322,8 @@ export const currencyName = (code: string, conversion: UnitConversion | null): s
 
 /** The exchange-rate and deflator tables behind the converted series, one
  *  line per table, each named once. */
-const conversionTables = (spec: any): string[] => {
-    const lines = (spec?.observations?.series ?? []).flatMap((series: any) => {
+const conversionTables = (spec: SpecReading): string[] => {
+    const lines = (spec?.observations?.series ?? []).flatMap((series) => {
         const conversion = series?.conversion;
 
         if (!conversion) return [];
@@ -337,7 +342,7 @@ const conversionTables = (spec: any): string[] => {
     return [...new Set<string>(lines)];
 };
 
-const unitAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
+const unitAbout = (token: SentenceToken, spec: SpecReading): TokenAboutModel => {
     const basis = priceBasis(spec);
     const unit = spec?.facets?.unit;
     const code: string | null = unit?.currency ?? null;
@@ -355,25 +360,25 @@ const unitAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
 
 /** The provenances the source token names: the source slot's bound values,
  *  else the sources the engine resolved. */
-const sourceRefs = (spec: any): any[] => {
-    const binding = (spec?.slots ?? []).find((slot: any) => slot?.key?.axis === 'source')?.binding;
+const sourceRefs = (spec: SpecReading): (GraphRef | ProvenanceRef)[] => {
+    const binding = (spec?.slots ?? []).find((slot) => slot?.key?.axis === 'source')?.binding;
     const bound =
         binding?.kind === 'value'
             ? [binding.value?.ref]
             : binding?.kind === 'set'
-              ? (binding.values ?? []).map((value: any) => value?.ref)
+              ? (binding.values ?? []).map((value) => value?.ref)
               : [];
-    const resolved: any[] = spec?.resolution?.resolved_sources ?? [];
-    const refs = bound.filter((ref: any) => ref?.ref);
+    const resolved = spec?.resolution?.resolved_sources ?? [];
+    const refs = bound.filter((ref): ref is GraphRef => !!ref?.ref);
 
     // A bound ref carries no publisher, so take the resolved one's when it
     // names the same provenance.
     return refs.length > 0
-        ? refs.map((ref: any) => resolved.find((r) => r?.ref === ref.ref) ?? ref)
+        ? refs.map((ref) => resolved.find((r) => r?.ref === ref.ref) ?? ref)
         : resolved;
 };
 
-const sourceAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
+const sourceAbout = (token: SentenceToken, spec: SpecReading): TokenAboutModel => {
     const sources: AboutSource[] = sourceRefs(spec).map((ref) => ({
         dcid: ref.ref,
         label: ref.label ?? ref.ref,
@@ -397,7 +402,7 @@ const sourceAbout = (token: SentenceToken, spec: any): TokenAboutModel => {
  *  list) reads as a code. */
 export const tokenAbout = (
     token: SentenceToken,
-    spec: any,
+    spec: SpecReading,
     statedElsewhere: ReadonlySet<string> = new Set(),
 ): TokenAboutModel => {
     if (token.axis === 'what') return measureAbout(token, spec, statedElsewhere);
diff --git a/src/lib/search/types.ts b/src/lib/search/types.ts
index 2fd5a9a..03ea585 100644
--- a/src/lib/search/types.ts
+++ b/src/lib/search/types.ts
@@ -191,12 +191,22 @@ export type FacetOptionsEntry = Omit<wire.FacetOptions, 'source'>;
  * held, so the page shows a failure state in its place.
  */
 export type UnreadableSpec = Pick<Spec, 'spec_id'> &
-    Partial<Omit<Spec, 'spec_id' | 'stat_vars'>> & { stat_vars_unreadable: true };
+    Partial<Omit<Spec, 'spec_id' | 'stat_vars'>> & {
+        stat_vars_unreadable: true;
+        /** the raw value that failed to read, when the body held one */
+        stat_vars?: unknown;
+    };
 
 /** A Spec as a part holds it: read, or flagged unreadable. `view.statVarsUnreadable` tells them
  *  apart. */
 export type PartSpec = Spec | UnreadableSpec;
 
+/** A spec as the view helpers read it: a part's spec, read or unreadable, or a copy holding only
+ *  the members its caller has. Any member may be absent, so each reader checks the ones it names.
+ *  An unreadable spec's `stat_vars` reads as `unknown` until `view.statVarsUnreadable` rules it
+ *  out. */
+export type SpecReading = Partial<Spec> | UnreadableSpec;
+
 /** A set of competing Specs, each flattened. */
 type CandidateSet = Omit<wire.CandidateSet, 'specs'> & { specs: PartSpec[] };
 
diff --git a/src/lib/search/unitLabel.ts b/src/lib/search/unitLabel.ts
index 5095640..ad548d0 100644
--- a/src/lib/search/unitLabel.ts
+++ b/src/lib/search/unitLabel.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads specs as `any`, dereferencing only the members it names and tolerating any that is missing */
 /**
  * The unit the way the byline names it, with the price basis ("Constant 2020
  * US dollars", "Current euros"). The Spec's unit facet names the currency
@@ -6,7 +5,7 @@
  * A leaf module: view.ts and tokenAbout.ts both import it.
  */
 
-import type { SentenceToken, UnitConversion } from './types.ts';
+import type { IdentityUnitRequest, SpecReading } from './types.ts';
 
 export type PriceBasis = { prices: 'current' | 'constant'; baseYear: number | null };
 
@@ -18,14 +17,26 @@ const PRICES_BY_QUALIFIER: Record<string, PriceBasis['prices']> = {
     RealValue: 'constant',
 };
 
+/** The unit request the spec's identity binds, when it binds one. */
+export const unitRequest = (
+    spec: Pick<SpecReading, 'identity'> | null | undefined,
+): IdentityUnitRequest | undefined => {
+    const unit = spec?.identity?.facets?.unit;
+
+    return unit && 'request' in unit ? unit.request : undefined;
+};
+
+const isPrices = (prices: string): prices is PriceBasis['prices'] =>
+    prices === 'current' || prices === 'constant';
+
 /** The answer's price basis, by the API's own precedence: the identity's
  *  unit request, then a unit in constant prices of a year
  *  ("ChainedUSDollarBaseYr2017"), then the measure's qualifier (Nominal,
  *  RealValue). Null when nothing states one. */
-export const priceBasis = (spec: any): PriceBasis | null => {
-    const request = spec?.identity?.facets?.unit?.request;
+export const priceBasis = (spec: SpecReading | null | undefined): PriceBasis | null => {
+    const request = unitRequest(spec);
 
-    if (request?.prices) {
+    if (request && isPrices(request.prices)) {
         return { prices: request.prices, baseYear: request.base_year ?? null };
     }
 
@@ -34,7 +45,7 @@ export const priceBasis = (spec: any): PriceBasis | null => {
     if (baseYear) return { prices: 'constant', baseYear: Number(baseYear) };
 
     const qualifier = (spec?.measure_axis_values ?? []).find(
-        (entry: any) => entry?.axis === QUALIFIER_AXIS,
+        (entry) => entry?.axis === QUALIFIER_AXIS,
     )?.value?.ref;
     const prices = qualifier ? PRICES_BY_QUALIFIER[qualifier] : undefined;
 
@@ -46,21 +57,19 @@ export const priceBasis = (spec: any): PriceBasis | null => {
  *  gives the currency, composed the way the byline composes them. Null for a
  *  unit that is no currency, or a currency with no stated basis or no noun,
  *  which the caller names itself. */
-export const unitWithBasis = (spec: any): string | null => {
+export const unitWithBasis = (spec: SpecReading | null | undefined): string | null => {
     const currency: string | null = spec?.facets?.unit?.currency ?? null;
 
     if (!currency) return null;
 
     const token = (spec?.sentence_plan ?? []).find(
-        (entry: SentenceToken) => entry.axis === 'unit' && entry.segment === 'byline' && entry.text,
+        (entry) => entry.axis === 'unit' && entry.segment === 'byline' && entry.text,
     );
 
     if (token) return token.text;
 
     const basis = priceBasis(spec);
-    const noun = spec?.unit_conversion?.currencies.find(
-        (entry: UnitConversion['currencies'][number]) => entry.code === currency,
-    )?.noun;
+    const noun = spec?.unit_conversion?.currencies.find((entry) => entry.code === currency)?.noun;
 
     if (!basis || !noun) return null;
 
diff --git a/src/lib/search/unitPicker.ts b/src/lib/search/unitPicker.ts
index aa93f44..7356a4e 100644
--- a/src/lib/search/unitPicker.ts
+++ b/src/lib/search/unitPicker.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads the flattened wire Spec */
 /**
  * The pure half of the unit token's picker (UnitPicker.tsx): which currency
  * and price basis the answer is in, the preset currencies to offer, the
@@ -13,12 +12,13 @@ import type { DatasetEntriesOverride } from './datasetEntries.ts';
 import { capitalise } from '../capitalise.ts';
 import { withFacetEdit } from './promote.ts';
 import { currencyName } from './tokenAbout.ts';
-import { priceBasis } from './unitLabel.ts';
+import { priceBasis, unitRequest } from './unitLabel.ts';
 import type {
     ConversionCurrency,
     EntityRoleKey,
     HydratedPart,
     IdentityUnitRequest,
+    SpecReading,
     UnitConversion,
 } from './types.ts';
 
@@ -59,8 +59,8 @@ const ROLE_NAMES: Record<EntityRoleKey, string> = {
 const REQUEST_ROLES = new Set<EntityRoleKey>(['origin', 'destination']);
 
 /** The answer's conversion offer, null when it cannot be converted. */
-export const unitConversion = (spec: any): UnitConversion | null => {
-    const conversion: UnitConversion | null | undefined = spec?.unit_conversion;
+export const unitConversion = (spec: SpecReading | null | undefined): UnitConversion | null => {
+    const conversion = spec?.unit_conversion;
 
     return conversion && conversion.currencies.length > 0 ? conversion : null;
 };
@@ -155,8 +155,8 @@ const requestCode = (
 
 /** The answer's unit: the identity's unit request when it carries one,
  *  else the served currency and the measure's price basis. */
-export const currentUnit = (spec: any): CurrentUnit => {
-    const request: IdentityUnitRequest | undefined = spec?.identity?.facets?.unit?.request;
+export const currentUnit = (spec: SpecReading | null | undefined): CurrentUnit => {
+    const request = unitRequest(spec);
     const basis = priceBasis(spec);
 
     return {
@@ -178,7 +178,10 @@ export const currentUnit = (spec: any): CurrentUnit => {
  * preset takes the preset's place under the entity's name. An entity with
  * no name is named by its role, and the row requests the role's currency.
  */
-export const unitPresets = (spec: any, conversion: UnitConversion | null): UnitPreset[] => {
+export const unitPresets = (
+    spec: SpecReading | null | undefined,
+    conversion: UnitConversion | null,
+): UnitPreset[] => {
     if (!conversion) return [];
 
     const offered = new Set(conversion.currencies.map((currency) => currency.code));
@@ -189,7 +192,7 @@ export const unitPresets = (spec: any, conversion: UnitConversion | null): UnitP
             label: capitalise(currencyName(code, conversion)),
             currency: code,
         }));
-    const entities: any[] = spec?.entities ?? [];
+    const entities = spec?.entities ?? [];
 
     for (const [role, code] of Object.entries(conversion.role_currencies ?? {}) as [
         EntityRoleKey,
diff --git a/src/lib/search/view.ts b/src/lib/search/view.ts
index ae2b47b..9de15d2 100644
--- a/src/lib/search/view.ts
+++ b/src/lib/search/view.ts
@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/no-explicit-any -- reads specs and options of either picker shape as `any`, each helper dereferencing only the members it names and tolerating any that is missing */
 /**
  * View helpers: flatten a resolved Spec into UI-ready rows and summaries.
  * Deliberately defensive — the engine contract is authoritative, the UI reads
@@ -16,6 +15,16 @@ import type { EntityChoiceGroup } from './parsedEdit.ts';
 import { entityOptionDcid } from './pickerState.ts';
 import type { OptionLike } from './pickerState.ts';
 import type { ApiError, EntityOption } from './searchClient';
+import type {
+    BreadthDim,
+    DateRange,
+    DownloadFacts,
+    ProvenanceRef,
+    ResolvedFacet,
+    ResolvedStatVars,
+    ShapeUpstream,
+} from '@developmentfinance/client/wire';
+
 import {
     type Assumption,
     type EntityOptions,
@@ -25,10 +34,12 @@ import {
     type GraphRef,
     hasKey,
     type IdentityFacetBinding,
+    knownPart,
     type Known,
     type NoData,
     type NoDataDenominator,
     type NoDataGate,
+    type NoDataPart,
     type NoDataReason,
     type ObservationsOmission,
     type ObservationsOmissionReason,
@@ -39,9 +50,12 @@ import {
     type PlaceOptionsScope,
     type RoleAxis,
     type SentenceToken,
+    type Shape,
     type Slot,
     type SlotOption,
     type Spec,
+    type SpecReading,
+    type TimeWindow,
     type UnitAlternative,
     type UnreadableSpec,
     type Warning,
@@ -53,12 +67,15 @@ import { unitWithBasis } from './unitLabel.ts';
 export const optionLabel = (option: OptionLike | null | undefined): string =>
     option?.value?.ref?.label ?? option?.label ?? '—';
 
+/** True for a non-empty string, which drops the refs a list leaves absent. */
+const isRef = (ref: string | null | undefined): ref is string => !!ref;
+
 /** True when searchClient.flattenSpec could not read this spec, because its `stat_vars`
  *  is not the wire's ResolvedStatVars object shape or it lacks the
  *  definition/resolved split, and logged the raw value to the
  *  console at parse time. A card reading this spec's variable label should
  *  show a failure state. */
-export function statVarsUnreadable(spec: PartSpec | null | undefined): spec is UnreadableSpec {
+export function statVarsUnreadable(spec: SpecReading | null | undefined): spec is UnreadableSpec {
     return !!spec && 'stat_vars_unreadable' in spec;
 }
 
@@ -66,13 +83,13 @@ export function statVarsUnreadable(spec: PartSpec | null | undefined): spec is U
  *  variable_text: its measure label, else its shape's label. Null when
  *  neither is stated — check statVarsUnreadable first to tell an unread
  *  spec from an unnamed one. */
-export const primaryStatVarLabel = (spec: any): string | null =>
+export const primaryStatVarLabel = (spec: SpecReading): string | null =>
     spec?.measure_label ?? spec?.shape?.label ?? null;
 
 /** A part's own variable_text for a card standing in for that part, or the
  *  full original question when the fallback needs more than the bare
  *  variable. */
-export const cardText = (spec: any, fallbackText?: string | null): string | undefined =>
+export const cardText = (spec: SpecReading, fallbackText?: string | null): string | undefined =>
     sentenceOf(spec)?.rendered_sentence ?? fallbackText ?? undefined;
 
 /** One facet axis's observed choices off `spec.facet_options`, deduped by
@@ -117,7 +134,7 @@ const facetAxisOptions = (
  * such a ref comes back definite with the sentence gaining "according to …".
  * Reshaped to the slot-option contract so the pickers treat them uniformly.
  */
-export const sourceSlotOptions = (spec: any): SourceSlotOption[] =>
+export const sourceSlotOptions = (spec: SpecReading): SourceSlotOption[] =>
     facetAxisOptions(spec, 'provenance').filter(
         (option): option is SourceSlotOption =>
             !!option.value.ref && option.value.value_kind === 'source',
@@ -141,19 +158,29 @@ export const sourceOptionLabel = (option: OptionLike | null | undefined): string
  *  beside its own label. Reads any ref carrying `source` and `data_commons`
  *  (a ProvenanceRef, a series' facet.provenance, resolved.facets.provenance,
  *  a ShapeUpstream). */
-export const provenanceOrigin = (provenance: any): string | null =>
-    originLine(provenance?.ref, provenance?.source, provenance?.data_commons);
+export const provenanceOrigin = (
+    provenance:
+        | Pick<ResolvedFacet, 'ref' | 'label' | 'source' | 'data_commons'>
+        | ShapeUpstream
+        | null
+        | undefined,
+): string | null =>
+    originLine(
+        provenance && 'ref' in provenance ? provenance.ref : null,
+        provenance?.source,
+        provenance?.data_commons,
+    );
 
 /** A candidate's origin before any series is read, from its shape: the one
  *  upstream source when there is one, else the Data Commons holding its
  *  variables. Null when DFO is among them, because at a place both hold the
  *  series serves DFO's data. */
-export const shapeOrigin = (shape: any): string | null => {
+export const shapeOrigin = (shape: Shape | null | undefined): string | null => {
     if (shape?.upstream) {
         return provenanceOrigin(shape.upstream);
     }
 
-    const origins: any[] = shape?.data_commons ?? [];
+    const origins = shape?.data_commons ?? [];
 
     if (origins.some((origin) => origin?.id === 'dfo')) {
         return null;
@@ -167,24 +194,24 @@ export const shapeOrigin = (shape: any): string | null => {
 /** The provenance dcids a spec's own sentence names in its source slot: the
  *  bound source values, else the resolved sources the engine renders when
  *  the slot is unbound. Empty when the sentence names no source. */
-const sentenceSourceRefs = (spec: any): string[] => {
+const sentenceSourceRefs = (spec: SpecReading): string[] => {
     const named = (spec?.sentence_plan ?? []).some(
-        (token: any) => token?.kind === 'slot' && token.axis === 'source' && token.text,
+        (token) => token?.kind === 'slot' && token.axis === 'source' && token.text,
     );
 
     if (!named) {
         return [];
     }
 
-    const binding = (spec?.slots ?? []).find((slot: any) => slot?.key?.axis === 'source')?.binding;
-    const refs: any[] =
+    const binding = (spec?.slots ?? []).find((slot) => slot?.key?.axis === 'source')?.binding;
+    const refs: (GraphRef | null | undefined)[] =
         binding?.kind === 'value'
             ? [binding.value?.ref]
             : binding?.kind === 'set'
-              ? binding.values.map((value: any) => value?.ref)
+              ? binding.values.map((value) => value?.ref)
               : (spec?.resolution?.resolved_sources ?? []);
 
-    return refs.map((ref) => ref?.ref).filter(Boolean);
+    return refs.map((ref) => ref?.ref).filter(isRef);
 };
 
 /** The origin beside a title built from the spec's own sentence (a
@@ -192,7 +219,7 @@ const sentenceSourceRefs = (spec: any): string[] => {
  *  when the sentence's source slot already names it. A UN agency answer
  *  reads "... according to United Nations Children's Fund", so its line is
  *  "via UN System Data Commons" alone. */
-export const specOrigin = (spec: any): string | null => {
+export const specOrigin = (spec: SpecReading): string | null => {
     const upstream = spec?.shape?.upstream;
 
     if (upstream && sentenceSourceRefs(spec).includes(upstream.source?.ref)) {
@@ -206,11 +233,11 @@ export const specOrigin = (spec: any): string | null => {
  *  provenance refs the spec carries: the trace's resolved_sources,
  *  resolved.facets.provenance, then each series' source_refs. The source
  *  picker's options are bare GraphRefs, so this is how they get theirs. */
-export const sourceOrigin = (spec: any, dcid: string): string | null => {
-    const refs: any[] = [
+export const sourceOrigin = (spec: SpecReading, dcid: string): string | null => {
+    const refs: (ProvenanceRef | ResolvedFacet | undefined)[] = [
         ...(spec?.resolution?.resolved_sources ?? []),
         spec?.facets?.provenance,
-        ...(spec?.observations?.series ?? []).flatMap((series: any) => series?.source_refs ?? []),
+        ...(spec?.observations?.series ?? []).flatMap((series) => series?.source_refs ?? []),
     ];
 
     return provenanceOrigin(refs.find((ref) => ref?.ref === dcid));
@@ -226,6 +253,9 @@ export type EntityOptionsEntry = Pick<
 
 export type EntityOptionsBySpec = Record<string, EntityOptionsEntry[]>;
 
+/** A spec as the spec_id-keyed option maps look it up. */
+type KeyedSpec = Pick<Spec, 'spec_id'> | null | undefined;
+
 /** Fold one trailing entity_options event into its spec-keyed map without
  * losing the event's truncation state. */
 export const mergeEntityOptionsEntry = (
@@ -241,14 +271,14 @@ export const mergeEntityOptionsEntry = (
  * Sentence tokens carry the authoritative role, including an open
  * destination that identity.entities does not yet contain. */
 export const entityOptionsEntry = (
-    spec: any,
+    spec: KeyedSpec,
     entityOptionsBySpec: EntityOptionsBySpec,
     role: RoleAxis,
 ): EntityOptionsEntry | undefined =>
-    (entityOptionsBySpec[spec?.spec_id] ?? []).find((entry) => entry.role === role);
+    ((spec && entityOptionsBySpec[spec.spec_id]) ?? []).find((entry) => entry.role === role);
 
 export const entitySlotOptions = (
-    spec: any,
+    spec: KeyedSpec,
     entityOptionsBySpec: EntityOptionsBySpec,
     role: RoleAxis,
 ) => entityOptionsEntry(spec, entityOptionsBySpec, role)?.options ?? [];
@@ -257,7 +287,7 @@ export const entitySlotOptions = (
  * shared directional token. A representative part may offer a recipient the
  * others cannot accept, so a hoisted menu may only expose the intersection. */
 export const sharedEntityOptions = (
-    specs: any[],
+    specs: KeyedSpec[],
     entityOptionsBySpec: EntityOptionsBySpec,
     role: RoleAxis,
 ): EntityOptionsEntry | undefined => {
@@ -298,14 +328,14 @@ export const sharedDirectionalEditRoute = (
 };
 
 /** The dcid of a spec's currently-bound entity for a directional role. */
-export const currentEntityDcid = (spec: any, role: EntityRoleKey): string | undefined =>
-    (spec?.entities ?? []).find((entity: any) => entity.role === role)?.ref;
+export const currentEntityDcid = (spec: SpecReading, role: EntityRoleKey): string | undefined =>
+    (spec?.entities ?? []).find((entity) => entity.role === role)?.ref;
 
 /** An open directional axis has no entity_ref but still exposes its own
  * candidate set. Add Criteria uses this for the origin axis, whose sentence
  * plan deliberately has no token while it is open. */
 export const openEntityEntry = (
-    spec: any,
+    spec: KeyedSpec,
     entityOptionsBySpec: EntityOptionsBySpec,
     role: RoleAxis,
 ): EntityOptionsEntry | undefined => {
@@ -316,20 +346,19 @@ export const openEntityEntry = (
 /** A set binding reads its first value as a representative anchor good
  *  enough to gate "is anything bound". currentEntityDcids is the one to
  *  read for the full bound set. */
-export const anchorDcid = (token: SentenceToken, spec: any): string | undefined => {
+export const anchorDcid = (token: SentenceToken, spec: SpecReading): string | undefined => {
     if (token.entity_refs?.length) return token.entity_refs[0];
 
     if (token.axis !== 'where') return undefined;
 
-    const binding = (spec?.slots ?? []).find((slot: any) => slot?.key?.axis === 'where')?.binding;
+    const binding = (spec?.slots ?? []).find((slot) => slot?.key?.axis === 'where')?.binding;
 
     if (binding?.kind === 'value' && binding.value?.value_kind === 'entity') {
         return binding.value?.ref?.ref;
     }
 
     if (binding?.kind === 'set') {
-        return (binding.values ?? []).find((value: any) => value?.value_kind === 'entity')?.ref
-            ?.ref;
+        return (binding.values ?? []).find((value) => value?.value_kind === 'entity')?.ref?.ref;
     }
 
     return undefined;
@@ -337,16 +366,18 @@ export const anchorDcid = (token: SentenceToken, spec: any): string | undefined
 
 /** Plural sibling of currentEntityDcid (which stops at the first match),
  *  used wherever more than one entity can be bound to a role at once. */
-export const currentEntityDcids = (spec: any, role: EntityRoleKey): string[] =>
+export const currentEntityDcids = (spec: SpecReading, role: EntityRoleKey): string[] =>
     (spec?.entities ?? [])
-        .filter((entity: any) => entity.role === role)
-        .map((entity: any) => entity.ref)
+        .filter((entity) => entity.role === role)
+        .map((entity) => entity.ref)
         .filter((ref: unknown): ref is string => typeof ref === 'string' && ref.length > 0);
 
 /** BindingSet is illegal at length 1, so a single ref renders as a plain
  *  value and only two or more become a set. Zero clears the slot the same
  *  way "Any place" already does. */
-export const entitySlotBindingForRefs = (refs: { dcid: string; label: string }[]): any => {
+export const entitySlotBindingForRefs = (
+    refs: { dcid: string; label: string }[],
+): Slot['binding'] => {
     if (refs.length === 0) return { kind: 'unbound' };
 
     const values = refs.map((ref) => ({
@@ -371,7 +402,7 @@ export const entitySlotBindingForRefs = (refs: { dcid: string; label: string }[]
  */
 export const placeEditorPickRoute = (
     token: SentenceToken,
-    spec: any,
+    spec: SpecReading,
 ):
     | { kind: 'entity'; role: RoleAxis }
     | { kind: 'where'; whereIndex: number }
@@ -380,7 +411,7 @@ export const placeEditorPickRoute = (
         return { kind: 'entity', role: token.role };
     }
 
-    const whereIndex = (spec?.slots ?? []).findIndex((slot: any) => slot?.key?.axis === 'where');
+    const whereIndex = (spec?.slots ?? []).findIndex((slot) => slot?.key?.axis === 'where');
 
     // No where slot to bind: the pick falls back to the typed-text path.
     return whereIndex === -1 ? { kind: 'text' } : { kind: 'where', whereIndex };
@@ -438,10 +469,10 @@ export type PlaceOptionsBySpec = Record<
  *  spec no event has named yet (the trailing events haven't arrived, or this
  *  spec binds no observationAbout place at all). */
 export const placeOptionsForSpec = (
-    spec: any,
+    spec: KeyedSpec,
     placeOptionsBySpec: PlaceOptionsBySpec,
 ): Partial<Record<PlaceOptionsScope, PlaceOptionsEntry>> | undefined =>
-    placeOptionsBySpec[spec?.spec_id];
+    spec ? placeOptionsBySpec[spec.spec_id] : undefined;
 
 /** Fold one trailing place_options event into its spec-keyed map. Unlike
  *  mergeEntityOptionsEntry's append, a (spec_id, scope) pair has at most one
@@ -853,8 +884,10 @@ export const mergeSlotOptionsEntry = (
  *  reads the taxonomy label directly. The one check both a bound slot's
  *  menu and Add Criteria's submenu need, so the same slot doesn't gain a
  *  different label depending on which entry point rendered it. */
-export const slotOptionLabel = (slot: any, option: OptionLike): string =>
-    slot?.key?.axis === 'source' ? sourceOptionLabel(option) : optionLabel(option);
+export const slotOptionLabel = (
+    slot: Pick<Slot, 'key'> | null | undefined,
+    option: OptionLike,
+): string => (slot?.key?.axis === 'source' ? sourceOptionLabel(option) : optionLabel(option));
 
 /** "1,284 rows", or "up to 1,284 rows" when `exact` is false, for a count
  *  in the terms of `DownloadFacts.rows`: a slot option's or measure
@@ -868,17 +901,21 @@ export const rowsLabel = (
 
 /** The dcids a slot binds: one for a value, each member's for a set, none
  *  when unbound. */
-const slotBoundDcids = (slot: any): string[] => {
+const slotBoundDcids = (slot: Pick<Slot, 'binding'> | null | undefined): string[] => {
     const binding = slot?.binding;
 
-    if (binding?.kind === 'value') return [binding.value?.ref?.ref].filter(Boolean);
+    if (binding?.kind === 'value') return [binding.value?.ref?.ref].filter(isRef);
     if (binding?.kind === 'set') {
-        return (binding.values ?? []).map((value: any) => value?.ref?.ref).filter(Boolean);
+        return (binding.values ?? []).map((value) => value?.ref?.ref).filter(isRef);
     }
 
     return [];
 };
 
+/** A spec's StatVar membership; none for a spec whose `stat_vars` failed to read. */
+export const readStatVars = (spec: SpecReading): ResolvedStatVars | undefined =>
+    statVarsUnreadable(spec) ? undefined : spec.stat_vars;
+
 /** The StatVars a Spec serves, counted from its resolved membership: the
  *  members door's list once it names any (`listed`), else
  *  `stat_vars.served_count` once membership settled, else the family's
@@ -887,10 +924,10 @@ const slotBoundDcids = (slot: any): string[] => {
  *  dimension counts the variables with data in the answer's rows, so it
  *  takes no part. */
 const servedMembership = (
-    spec: any,
+    spec: SpecReading,
     listed?: MemberRef[] | null,
 ): { count: number; exact: boolean } | null => {
-    const statVars = spec?.stat_vars;
+    const statVars = readStatVars(spec);
     const served: number | null = listed?.length || (statVars?.served_count ?? null);
 
     if (served != null) return { count: served, exact: true };
@@ -901,7 +938,7 @@ const servedMembership = (
 
 /** How many StatVars the answer serves: the settled served count, else the
  *  family's count. */
-export const servedSeriesCount = (spec: any): number | null =>
+export const servedSeriesCount = (spec: SpecReading): number | null =>
     servedMembership(spec)?.count ?? null;
 
 /** Whether a slot's menu offers anything but what the answer already
@@ -912,7 +949,11 @@ export const servedSeriesCount = (spec: any): number | null =>
  *  two or more spanned options, or one counted option that serves fewer
  *  rows than `spec` (the answer) downloads. One uncounted option, or one
  *  that serves every row, narrows nothing. */
-export const slotOffersChoice = (slot: any, entry: SlotOptionsEntry, spec: any): boolean => {
+export const slotOffersChoice = (
+    slot: Pick<Slot, 'binding'> | null | undefined,
+    entry: SlotOptionsEntry,
+    spec: SpecReading,
+): boolean => {
     const bound = new Set(slotBoundDcids(slot));
     const binds = (option: SlotOption) => bound.has(option.value.ref?.ref ?? '');
 
@@ -1069,9 +1110,13 @@ export type WhySummary = {
 };
 
 // A time window as the user would say it: "since 2015", "2015 to 2020", "2023".
-export const formatWindow = (window: any): string | null => {
-    const start = window?.start_year ?? null;
-    const end = window?.end_year ?? null;
+export const formatWindow = (window: TimeWindow | 'latest' | null | undefined): string | null => {
+    if (window == null || window === 'latest') {
+        return null;
+    }
+
+    const start = window.start_year ?? null;
+    const end = window.end_year ?? null;
 
     if (start == null && end == null) {
         return null;
@@ -1104,7 +1149,7 @@ const orList = (labels: string[]): string =>
     new Intl.ListFormat('en-GB', { type: 'disjunction' }).format(labels);
 
 // The years a DateRange spans.
-const dateRange = (range: any): string | null => {
+const dateRange = (range: DateRange | null | undefined): string | null => {
     const start = range?.start?.slice(0, 4) ?? null;
     const end = range?.end?.slice(0, 4) ?? null;
 
@@ -1118,7 +1163,7 @@ const dateRange = (range: any): string | null => {
 // Years in order of precedence: the window the query named, the coverage
 // window, the span of the served variables' data, then the year a broad
 // answer counts.
-const yearsText = (spec: any): string | null => {
+const yearsText = (spec: SpecReading): string | null => {
     const named = formatWindow(spec.resolution?.requested_window);
 
     if (named) {
@@ -1131,7 +1176,7 @@ const yearsText = (spec: any): string | null => {
         return covered;
     }
 
-    const served = dateRange(spec.stat_vars?.data_date_range);
+    const served = dateRange(readStatVars(spec)?.data_date_range);
 
     if (served) {
         return served;
@@ -1157,21 +1202,27 @@ const variablesSummary = (count: number, exact: boolean, shapeLabel?: string | n
 };
 
 // The labels of the entities a spec binds to one role.
-const entityLabels = (spec: any, role: EntityRoleKey): string[] =>
+const entityLabels = (spec: SpecReading, role: EntityRoleKey): string[] =>
     (spec.entities ?? [])
-        .filter((entity: any) => entity?.role === role)
-        .map((entity: any) => entity?.label ?? entity?.ref)
+        .filter((entity) => entity?.role === role)
+        .map((entity) => entity?.label ?? entity?.ref)
         .filter(Boolean);
 
 // A coverage dimension's count ("recipients", "places"), null when absent.
-const dimensionCount = (spec: any, label: string): number | null =>
-    (spec?.coverage?.dimensions ?? []).find((dimension: any) => dimension?.label === label)
-        ?.count ?? null;
+export const dimensionCount = (spec: SpecReading, label: string): number | null =>
+    coverageDimensions(spec).find((dimension) => dimension?.label === label)?.count ?? null;
+
+// A spec's coverage dimensions; a bare coverage counts none.
+const coverageDimensions = (spec: SpecReading): BreadthDim[] => {
+    const coverage = spec?.coverage;
+
+    return (coverage && 'dimensions' in coverage ? coverage.dimensions : null) ?? [];
+};
 
 // The scope of a no-place answer. The API narrows one whose full place list
 // is too large to the countries with data, and its coverage then counts
 // "countries" where a full answer counts "places".
-const placeScope = (spec: any): { noun: string; many: string; count: number | null } => {
+const placeScope = (spec: SpecReading): { noun: string; many: string; count: number | null } => {
     const countries = dimensionCount(spec, 'countries');
 
     return countries != null
@@ -1181,11 +1232,11 @@ const placeScope = (spec: any): { noun: string; many: string; count: number | nu
 
 // The roles a spec leaves open: each role whose options came back with
 // nothing bound to it, and the place when no place was named.
-const openRoles = (spec: any, codes: Set<string>): EntityRoleKey[] => {
-    const bound = new Set((spec.entities ?? []).map((entity: any) => entity?.role));
+const openRoles = (spec: SpecReading, codes: Set<string>): EntityRoleKey[] => {
+    const bound = new Set((spec.entities ?? []).map((entity) => entity?.role));
     const open = (spec.entity_options ?? [])
-        .map((entry: any) => entry?.role)
-        .filter((role: any): role is EntityRoleKey => role in ROLE_WORDS && !bound.has(role));
+        .map((entry) => entry?.role)
+        .filter((role): role is EntityRoleKey => role in ROLE_WORDS && !bound.has(role));
 
     if (codes.has('place_scope_defaulted') && !bound.has('observationAbout')) {
         open.push('observationAbout');
@@ -1196,16 +1247,16 @@ const openRoles = (spec: any, codes: Set<string>): EntityRoleKey[] => {
 
 // The label of the slot `bindingRef` names on `spec` ("Type of flow"),
 // null when neither its trace nor its slots carry one.
-const slotLabelOf = (spec: any, bindingRef: string): string | null =>
+const slotLabelOf = (spec: SpecReading, bindingRef: string): string | null =>
     [...(spec.resolution?.slot_filters ?? []), ...(spec.slots ?? [])].find(
-        (entry: any) => entry?.key && keyRef(entry.key) === bindingRef,
+        (entry) => entry?.key && keyRef(entry.key) === bindingRef,
     )?.key?.label ?? null;
 
 const lowerFirst = (text: string): string =>
     /^[A-Z][a-z]/.test(text) ? text.charAt(0).toLowerCase() + text.slice(1) : text;
 
 // One assumption as the panel states it, in the words of its own `text`.
-const assumptionSentence = (spec: any, assumption: Assumption): string => {
+const assumptionSentence = (spec: SpecReading, assumption: Assumption): string => {
     const { kind, binding_ref: ref, text } = assumption;
 
     if (kind === 'place_scope') return `No place was named, so the answer covers ${text}.`;
@@ -1235,7 +1286,7 @@ const assumptionSentence = (spec: any, assumption: Assumption): string => {
  *  role-bearing answer can say no year was named without sending that
  *  warning. */
 export const scopeAssumptions = (
-    spec: any,
+    spec: SpecReading,
     assumptions: readonly Assumption[] | null | undefined,
     warnings?: readonly Pick<Warning, 'code'>[] | null,
 ): string[] => {
@@ -1263,21 +1314,28 @@ const BREAKDOWN_VALUES = 5;
 // The served variables counted by each value of every axis they differ on,
 // from open_axis_facts[].values, which the API counts over the distinct
 // served members.
-const variablesBreakdown = (spec: any): WhyBreakdown[] =>
-    (spec.open_axis_facts ?? [])
-        .filter((fact: any) => fact?.varies && fact.values?.length > 0)
-        .map((fact: any) => ({
-            title: `By ${axisLabel(spec, fact.property)}`,
-            values: fact.values.slice(0, BREAKDOWN_VALUES).map((entry: any) => ({
-                label: capitalise(entry.value?.label ?? entry.value?.ref ?? ''),
-                count: entry.count,
-            })),
-            more: Math.max(fact.values.length - BREAKDOWN_VALUES, 0),
-        }));
+const variablesBreakdown = (spec: SpecReading): WhyBreakdown[] =>
+    (spec.open_axis_facts ?? []).flatMap(({ property, varies, values }) =>
+        varies && values?.length
+            ? [
+                  {
+                      title: `By ${axisLabel(spec, property)}`,
+                      values: values.slice(0, BREAKDOWN_VALUES).map((entry) => ({
+                          label: capitalise(entry.value?.label ?? entry.value?.ref ?? ''),
+                          count: entry.count,
+                      })),
+                      more: Math.max(values.length - BREAKDOWN_VALUES, 0),
+                  },
+              ]
+            : [],
+    );
 
 // "This answer uses 1 of at least 3 variables.", null when
 // the answer serves every member stat_vars.member_count counts.
-const familyNote = (served: number, statVars: any): string | null => {
+const familyNote = (
+    served: number,
+    statVars: Partial<Pick<ResolvedStatVars, 'member_count' | 'member_count_exact'>>,
+): string | null => {
     const members = statVars.member_count;
 
     if (members == null || members <= served) {
@@ -1316,7 +1374,7 @@ const FACET_CHOICE_AXES = [
     ['unit', 'Unit'],
 ] as const;
 
-const facetChoiceValue = (axis: string, facet: any): string | null => {
+const facetChoiceValue = (axis: string, facet: ResolvedFacet): string | null => {
     if (facet.selection === 'per_series') {
         return 'Differs by series';
     }
@@ -1333,17 +1391,17 @@ const facetChoiceValue = (axis: string, facet: any): string | null => {
 // How each facet axis got its value (`resolved.facets[axis].basis`). A
 // slot a declared default filled is one of the part's `assumptions`, which
 // "What we assumed" states (scopeAssumptions).
-const whyChoices = (spec: any): WhyChoice[] =>
+const whyChoices = (spec: SpecReading): WhyChoice[] =>
     FACET_CHOICE_AXES.flatMap(([axis, label]) => {
         const facet = spec.facets?.[axis];
         const reason: string | undefined = facet && CHOICE_REASONS[facet.basis as FacetBasis];
-        const value = reason ? facetChoiceValue(axis, facet) : null;
+        const value = facet && reason ? facetChoiceValue(axis, facet) : null;
 
         return reason && value ? [{ label, value, reason }] : [];
     });
 
 // The licence label of the one source the answer serves, in words.
-const licenceText = (spec: any): string | null =>
+const licenceText = (spec: SpecReading): string | null =>
     spec?.download?.licence?.label ? spaceCamel(spec.download.licence.label) : null;
 
 /** The "About this answer" summary for one definite part: what the search
@@ -1366,17 +1424,17 @@ const licenceText = (spec: any): string | null =>
  *  Coverage's "variables" dimension counts the variables with data in the
  *  answer's rows and chooses nothing here. */
 export const buildWhySummary = (
-    spec: any,
+    spec: SpecReading,
     part?: Pick<Part, 'warnings' | 'variable_text'> | null,
     members?: MembersRead | null,
 ): WhySummary => {
-    const statVars = spec.stat_vars ?? {};
+    const statVars = readStatVars(spec) ?? {};
     const listed = members?.ok ? members.members : null;
     const { count, exact } = servedMembership(spec, listed) ?? { count: 0, exact: true };
     const single = exact && count === 1;
     const member = single && listed?.length === 1 ? listed[0] : null;
     const codes = new Set((part?.warnings ?? []).map((warning) => warning?.code));
-    const sources: any[] = spec.resolution?.resolved_sources ?? [];
+    const sources = spec.resolution?.resolved_sources ?? [];
 
     const name = member
         ? (member.label ?? member.dcid)
@@ -1449,7 +1507,7 @@ export const buildWhySummary = (
         rows,
         family: count > 0 ? familyNote(count, statVars) : null,
         variables,
-        sources: sources.map((ref: any) => ({
+        sources: sources.map((ref) => ({
             ref: ref.ref,
             label: ref.label ?? ref.ref,
             documentation: ref.documentation ?? null,
@@ -1494,7 +1552,7 @@ const roleScope = (count: number, members: number | null, noun: string): string
  *  scope: the year the counts are for, the values in that year, and each
  *  open role's count against the members with data in any year. A named
  *  provider or recipient closes the sentence. Null without a headline. */
-export const coverageSentence = (spec: any): string | null => {
+export const coverageSentence = (spec: SpecReading): string | null => {
     const headline = spec?.headline;
 
     if (headline?.year == null || headline.observations == null) {
@@ -1548,7 +1606,7 @@ export const coverageSentence = (spec: any): string | null => {
 export const seriesPreviewCaptions = (
     parts: {
         variableText: string | null;
-        spec: any;
+        spec: SpecReading | null | undefined;
         warnings?: Pick<Warning, 'code' | 'params'>[];
     }[],
 ): string[] =>
@@ -1605,7 +1663,9 @@ const UNIT_SYMBOLS: Record<string, string> = {
     Percentage: '%',
 };
 
-export const formatUnit = (unit: any): string | null => {
+export const formatUnit = (
+    unit: { ref?: string | null; label?: string | null } | null | undefined,
+): string | null => {
     const ref: string | null = unit?.ref ?? null;
     const label: string | null = unit?.label ?? null;
 
@@ -1626,7 +1686,9 @@ export const formatUnit = (unit: any): string | null => {
  *  an unlabelled node, so it counts as no label. Null when there is no
  *  method. The picker, its trigger and the Method column all read method
  *  text through here; the posted binding keeps the dcid. */
-export const formatMethod = (method: any): string | null => {
+export const formatMethod = (
+    method: { ref?: string | null; label?: string | null } | null | undefined,
+): string | null => {
     const label: string | null = method?.label !== method?.ref ? (method?.label ?? null) : null;
     const raw: string | null = label ?? method?.ref?.split('/').at(-1) ?? null;
 
@@ -1636,12 +1698,12 @@ export const formatMethod = (method: any): string | null => {
 /** The spec-level unit (resolved.facets.unit), when the engine resolved one:
  *  a currency with its price basis as the byline states it ("Constant 2020
  *  US dollars"), any other unit by its symbol or label. */
-export const specUnit = (spec: any): string | null =>
+export const specUnit = (spec: SpecReading): string | null =>
     unitWithBasis(spec) ?? formatUnit(spec?.facets?.unit);
 
 // The unit in words ("Constant 2020 US dollars", "Percentage"), as the Why
 // panel and the download details name it.
-const unitText = (spec: any): string | null => {
+const unitText = (spec: SpecReading): string | null => {
     const unit = spec?.facets?.unit;
     const text = unit?.label ?? unit?.ref ?? null;
 
@@ -1659,8 +1721,8 @@ export const openAxisFactLabel = (property: string): string => {
 
 /** A constraint property's name for a reader: its slot's label
  *  ("instrument"), else `openAxisFactLabel`. */
-export const axisLabel = (spec: any, property: string): string =>
-    (spec?.slots ?? []).find((slot: any) => slot?.key?.property?.ref === property)?.key?.label ??
+export const axisLabel = (spec: SpecReading, property: string): string =>
+    (spec?.slots ?? []).find((slot) => slot?.key?.property?.ref === property)?.key?.label ??
     openAxisFactLabel(property);
 
 // The cell of a row whose part has no such column.
@@ -1672,19 +1734,19 @@ const ROLE_ORDER: string[] = ['origin', 'destination', 'observationAbout'];
 const entityKey = (role: string): string => `entity:${role}`;
 const axisKey = (property: string): string => `axis:${property}`;
 
-const slotOnAxis = (spec: any, axis: string): any =>
-    (spec?.slots ?? []).find((slot: any) => slot?.key?.axis === axis);
+const slotOnAxis = (spec: SpecReading, axis: string): Slot | undefined =>
+    (spec?.slots ?? []).find((slot) => slot?.key?.axis === axis);
 
-const slotOnProperty = (spec: any, property: string): any =>
-    (spec?.slots ?? []).find((slot: any) => slot?.key?.property?.ref === property);
+const slotOnProperty = (spec: SpecReading, property: string): Slot | undefined =>
+    (spec?.slots ?? []).find((slot) => slot?.key?.property?.ref === property);
 
 // The one value ref a slot binds, null for an unbound slot or a set.
-const boundRef = (slot: any): string | null =>
+const boundRef = (slot: Slot | null | undefined): string | null =>
     slot?.binding?.kind === 'value' ? (slot.binding.value?.ref?.ref ?? null) : null;
 
 // Provider and Recipient head their role's column. A single-role series'
 // entity takes the where slot's own label ("Place").
-const roleHeading = (spec: any, role: string): string =>
+const roleHeading = (spec: SpecReading, role: string): string =>
     role === 'origin' || role === 'destination'
         ? ROLE_WORDS[role].one
         : capitalise(slotOnAxis(spec, 'where')?.key?.label ?? ROLE_WORDS.observationAbout.one);
@@ -1696,21 +1758,21 @@ type PartColumn = PreviewColumn & { bound: string | null; named: boolean };
 
 // Whether some series carries `ObservationSeries.axes`. A table from an API
 // that predates the field, or from a share saved before it, has none.
-const carriesAxes = (spec: any): boolean =>
-    (spec?.observations?.series ?? []).some((s: any) => Array.isArray(s?.axes));
+const carriesAxes = (spec: SpecReading): boolean =>
+    (spec?.observations?.series ?? []).some((s) => Array.isArray(s?.axes));
 
 // A series' subject entity for a table without axes: the observationAbout
 // entry of its role tuple, else its first entity.
-const seriesEntity = (s: any): { role: string; label: string | null } => {
+const seriesEntity = (s: ObservationSeries): { role: string; label: string | null } => {
     const about =
-        (s?.entities ?? []).find((e: any) => e?.role === 'observationAbout') ?? s?.entities?.[0];
+        (s?.entities ?? []).find((e) => e?.role === 'observationAbout') ?? s?.entities?.[0];
 
     return { role: about?.role ?? 'observationAbout', label: about?.label ?? null };
 };
 
 // A slot's bound value labels, the text a table without axes shows in its
 // how and what columns.
-const slotLabel = (spec: any, axis: string): string => {
+const slotLabel = (spec: SpecReading, axis: string): string => {
     const binding = slotOnAxis(spec, axis)?.binding;
 
     if (binding?.kind === 'value') {
@@ -1718,7 +1780,7 @@ const slotLabel = (spec: any, axis: string): string => {
     }
 
     if (binding?.kind === 'set') {
-        const labels = (binding.values ?? []).map((v: any) => v?.ref?.label).filter(Boolean);
+        const labels = (binding.values ?? []).map((v) => v?.ref?.label).filter(Boolean);
 
         return labels.length ? labels.join(', ') : NO_CELL;
     }
@@ -1731,7 +1793,11 @@ const LEGACY_SLOT_HEADINGS: Record<string, string> = { how: 'Sector', what: 'Typ
 // The cells of one series' rows: one per entity role and one per axis
 // property, or, without axes, the subject entity and the how and what
 // slots' bound values.
-const seriesCells = (s: ObservationSeries, spec: any, axes: boolean): Record<string, string> => {
+const seriesCells = (
+    s: ObservationSeries,
+    spec: SpecReading,
+    axes: boolean,
+): Record<string, string> => {
     if (!axes) {
         const subject = seriesEntity(s);
 
@@ -1757,7 +1823,7 @@ const seriesCells = (s: ObservationSeries, spec: any, axes: boolean): Record<str
 
 // A series' refs per column: its entities' dcids by role and its axis
 // values by property.
-const seriesRefs = (s: any): Record<string, string> => {
+const seriesRefs = (s: ObservationSeries): Record<string, string> => {
     const refs: Record<string, string> = {};
 
     for (const entity of s?.entities ?? []) {
@@ -1775,8 +1841,8 @@ const seriesRefs = (s: any): Record<string, string> => {
 // the Spec's slot order and by property dcid after that. Without axes, the
 // subject entity and the how and what slots, none of them hidden for a
 // shared value.
-const partColumns = (spec: any): PartColumn[] => {
-    const series: any[] = spec?.observations?.series ?? [];
+const partColumns = (spec: SpecReading): PartColumn[] => {
+    const series = spec?.observations?.series ?? [];
 
     if (!carriesAxes(spec)) {
         const roles = [...new Set(series.map((s) => seriesEntity(s).role))];
@@ -1802,23 +1868,23 @@ const partColumns = (spec: any): PartColumn[] => {
     }
 
     const roles = [
-        ...new Set<string>(series.flatMap((s) => (s?.entities ?? []).map((e: any) => e.role))),
+        ...new Set<string>(series.flatMap((s) => (s?.entities ?? []).map((e) => e.role))),
     ].sort((a, b) => ROLE_ORDER.indexOf(a) - ROLE_ORDER.indexOf(b));
     // A role the Spec names one entity for binds that entity.
     const namedRef = (role: string): string | null => {
-        const refs = (spec?.entities ?? []).filter((e: any) => e?.role === role);
+        const refs = (spec?.entities ?? []).filter((e) => e?.role === role);
 
         return refs.length === 1 ? (refs[0].ref ?? null) : null;
     };
     const slotIndex = (property: string): number => {
         const index = (spec?.slots ?? []).findIndex(
-            (slot: any) => slot?.key?.property?.ref === property,
+            (slot) => slot?.key?.property?.ref === property,
         );
 
         return index === -1 ? Infinity : index;
     };
     const properties = [
-        ...new Set<string>(series.flatMap((s) => (s?.axes ?? []).map((a: any) => a.property))),
+        ...new Set<string>(series.flatMap((s) => (s?.axes ?? []).map((a) => a.property))),
     ].sort((a, b) => slotIndex(a) - slotIndex(b) || (a < b ? -1 : a > b ? 1 : 0));
 
     return [
@@ -1856,7 +1922,7 @@ const partColumns = (spec: any): PartColumn[] => {
  * stay distinguishable, and a constant unbound axis still shows. A column
  * with no text on any row is hidden too.
  */
-export const previewColumns = (parts: { spec: any }[]): PreviewColumn[] => {
+export const previewColumns = (parts: { spec: SpecReading }[]): PreviewColumn[] => {
     // Per column, the ref every part that offers it restates (null once one
     // does not, or two disagree) and whether any row has text for it.
     const offered = new Map<string, PartColumn & { restated: string | null; filled: boolean }>();
@@ -1870,7 +1936,7 @@ export const previewColumns = (parts: { spec: any }[]): PreviewColumn[] => {
 
         // The series behind the rows, those with points.
         const refs: Record<string, string>[] = (spec?.observations?.series ?? [])
-            .filter((s: any) => (s?.points ?? []).length > 0)
+            .filter((s) => (s?.points ?? []).length > 0)
             .map(seriesRefs);
 
         for (const column of partColumns(spec)) {
@@ -1922,7 +1988,9 @@ const seriesKinds = (s: ObservationSeries): Record<string, PartyKind> => {
  * total, across the rows of every part. A total beside a single party is
  * summed with nothing, so it stays unmarked.
  */
-export const markedTotalColumns = (parts: { spec: any }[]): ReadonlySet<string> => {
+export const markedTotalColumns = (
+    parts: { spec: SpecReading | null | undefined }[],
+): ReadonlySet<string> => {
     const parties = new Map<string, Set<string>>();
     const totals = new Set<string>();
 
@@ -1969,7 +2037,7 @@ export const previewCellText = (
 // `conversion` record), where the Spec's identity states the basis the
 // values were converted to. A preview that could not apply the conversion
 // keeps the unit the points are in.
-const seriesUnit = (series: ObservationSeries, spec: any): string | null =>
+const seriesUnit = (series: ObservationSeries, spec: SpecReading): string | null =>
     (series?.conversion ? unitWithBasis(spec) : null) ??
     formatUnit(series?.facet?.unit) ??
     formatUnit(spec?.facets?.unit);
@@ -1980,7 +2048,7 @@ export const observationSeries = (
     spec: Pick<Spec, 'observations'> | null | undefined,
 ): ObservationSeries[] => spec?.observations?.series ?? [];
 
-export const flattenRows = (spec: any): ResultRow[] => {
+export const flattenRows = (spec: SpecReading): ResultRow[] => {
     const axes = carriesAxes(spec);
 
     const rows: ResultRow[] = observationSeries(spec).flatMap((s) => {
@@ -2028,14 +2096,16 @@ export const methodCellText = (row: ResultRow): string => row.method ?? NO_METHO
  * a snapshot whose captured rows replace the replay's observations.
  * `resolved.facets.measurementMethod` stands in until series arrive.
  */
-const servedMethod = (spec: any): { ref?: string | null; label: string } => {
+const servedMethod = (
+    spec: SpecReading | null | undefined,
+): { ref?: string | null; label: string } => {
     const shown = (spec?.observations?.series ?? []).filter(
-        (series: any) => (series?.points ?? []).length > 0,
+        (series) => (series?.points ?? []).length > 0,
     );
 
     if (shown.length > 0) {
         const refs = new Set<string | null>(
-            shown.map((series: any) => series?.facet?.measurementMethod?.ref ?? null),
+            shown.map((series) => series?.facet?.measurementMethod?.ref ?? null),
         );
 
         if (refs.size > 1) {
@@ -2076,15 +2146,14 @@ const methodRefKey = (ref: string | null): string => ref ?? NO_METHOD_LABEL;
  * The trigger label names the bound method, else the one the table's
  * series were read from (`servedMethod`).
  */
-export const methodPicker = (spec: any): MethodPicker | null => {
+export const methodPicker = (spec: SpecReading | null | undefined): MethodPicker | null => {
     const options = facetAxisOptions(spec, 'measurementMethod');
 
     if (options.length === 0) {
         return null;
     }
 
-    const bound: IdentityFacetBinding['measurementMethod'] =
-        spec?.identity?.facets?.measurementMethod;
+    const bound = spec?.identity?.facets?.measurementMethod;
     const boundRefs: (string | null)[] =
         bound?.state === 'set' ? bound.refs : bound && 'ref' in bound ? [bound.ref] : [];
     const served = servedMethod(spec);
@@ -2123,7 +2192,7 @@ export const methodPicker = (spec: any): MethodPicker | null => {
 
 /** Whether a spec binds a method: the parts a shared method token speaks
  *  for, so the parts its menu reads and its pick applies to. */
-export const bindsMethod = (spec: any): boolean =>
+export const bindsMethod = (spec: SpecReading | null | undefined): boolean =>
     Boolean(spec?.identity?.facets?.measurementMethod);
 
 /** The choice key for a method binding: '' for Any method, else
@@ -2140,7 +2209,9 @@ const methodChoiceKey = (binding: MethodChoice['binding']): string | null => {
  * part offers. Any method is always kept; a part with no picker offers only
  * it. Null when no part has a picker.
  */
-export const sharedMethodPicker = (specs: any[]): MethodPicker | null => {
+export const sharedMethodPicker = (
+    specs: (SpecReading | null | undefined)[],
+): MethodPicker | null => {
     const pickers = specs.map(methodPicker);
     const first = pickers.find((picker) => picker !== null);
 
@@ -2159,7 +2230,10 @@ export const sharedMethodPicker = (specs: any[]): MethodPicker | null => {
 
 /** Whether every part in `specs` offers `binding`: the shared method menu
  *  lists it (`sharedMethodPicker`). */
-export const sharedMethodServes = (specs: any[], binding: MethodChoice['binding']): boolean => {
+export const sharedMethodServes = (
+    specs: (SpecReading | null | undefined)[],
+    binding: MethodChoice['binding'],
+): boolean => {
     const key = methodChoiceKey(binding);
 
     return (
@@ -2293,7 +2367,7 @@ export const observationsOmissionText = (
  * part's existing sort within it — nothing is re-sorted across parts.
  */
 export const flattenPartsRows = (
-    parts: { variableText: string | null; spec: any }[],
+    parts: { variableText: string | null; spec: SpecReading }[],
 ): PartResultRow[] =>
     parts.flatMap(({ variableText, spec }) =>
         flattenRows(spec).map((row) => ({
@@ -2439,11 +2513,14 @@ export const noDataText = (
  *  hands off when nothing close enough exists. Null when nearest_real is
  *  non-empty, which keeps its own cards branch instead. */
 export type NoDataCallout =
-    | { kind: 'flagged'; spec: any; text: string | undefined; editText: string | undefined }
-    | { kind: 'alternate'; spec: any; text: string | undefined; pickText: string | undefined }
+    | { kind: 'flagged'; spec: PartSpec; text: string | undefined; editText: string | undefined }
+    | { kind: 'alternate'; spec: PartSpec; text: string | undefined; pickText: string | undefined }
     | { kind: 'studio' };
 
-export const noDataCallout = (part: any, question?: string | null): NoDataCallout | null => {
+export const noDataCallout = (
+    part: Partial<Pick<NoDataPart, 'no_data' | 'variable_text'>> | null | undefined,
+    question?: string | null,
+): NoDataCallout | null => {
     const nearest = part?.no_data?.nearest_real ?? [];
 
     if (nearest.length > 0) {
@@ -2474,17 +2551,19 @@ export const noDataCallout = (part: any, question?: string | null): NoDataCallou
 
 /** A part's own status, in plain language, for a candidates/no_data/
  *  unsupported part — null for a definite (resolved) part. */
-export const unresolvedPartText = (part: any): string | null => {
-    if (part?.status === 'candidates') {
+export const unresolvedPartText = (part: Part | null | undefined): string | null => {
+    const known = knownPart(part);
+
+    if (known?.status === 'candidates') {
         return 'Needs a choice';
     }
 
-    if (part?.status === 'no_data') {
-        return noDataText(part.no_data);
+    if (known?.status === 'no_data') {
+        return noDataText(known.no_data);
     }
 
-    if (part?.status === 'unsupported') {
-        return part.unsupported?.detail ?? 'This query isn’t supported yet.';
+    if (known?.status === 'unsupported') {
+        return known.unsupported?.detail ?? 'This query isn’t supported yet.';
     }
 
     return null;
@@ -2563,28 +2642,29 @@ export const formatCount = (value: number | null | undefined): string =>
 // Best-available observation count: exact coverage carries observation_count,
 // breadth/bare coverage only carries dimensions (an 'observations' entry when
 // the engine could count them).
-export const observationCount = (spec: any): number | null => {
-    const direct = spec?.coverage?.observation_count ?? spec?.observations?.total_obs;
+export const observationCount = (spec: SpecReading): number | null => {
+    const coverage = spec?.coverage;
+    const direct =
+        (coverage && 'observation_count' in coverage ? coverage.observation_count : null) ??
+        spec?.observations?.total_obs;
 
     if (direct != null) {
         return direct;
     }
 
-    const dims = spec?.coverage?.dimensions ?? [];
-
-    return dims.find((d: any) => d?.label === 'observations')?.count ?? null;
+    return coverageDimensions(spec).find((d) => d?.label === 'observations')?.count ?? null;
 };
 
 // Card meta line: observations when countable, otherwise the widest dimension
 // the engine reported ("36 donors"), otherwise a plain has-data note.
-export const coverageSummary = (spec: any): string => {
+export const coverageSummary = (spec: SpecReading): string => {
     const count = observationCount(spec);
 
     if (count != null) {
         return `${formatCount(count)} observations`;
     }
 
-    const first = (spec?.coverage?.dimensions ?? [])[0];
+    const first = coverageDimensions(spec)[0];
 
     if (first?.count != null && first?.label) {
         return `${formatCount(first.count)} ${first.label}`;
@@ -2598,7 +2678,7 @@ export const coverageSummary = (spec: any): string => {
  *  main table of a long CSV or Excel download, which sets totals apart.
  *  `upTo` when the count is an upper bound. Null when the API could not count them without
  *  understating, or sent no download facts (a merged answer). */
-export const downloadRowCount = (spec: any): { rows: number; upTo: boolean } | null => {
+export const downloadRowCount = (spec: SpecReading): { rows: number; upTo: boolean } | null => {
     const download = spec?.download;
 
     return download?.rows != null
@@ -2626,16 +2706,15 @@ export const formatBytes = (bytes: number): string => {
  *  (`rows_exact` false, a conversion that drops the rows a rate table
  *  lacks), the years are one too, so a closed range reads "within 1973 to
  *  2024" and an open one, which cannot say that, is left out. */
-const detailYears = (download: any): string | null => {
-    const years = formatWindow(download?.window);
+const detailYears = (download: DownloadFacts | null | undefined): string | null => {
+    const window = download?.window;
+    const years = formatWindow(window);
 
-    if (!years || download.rows_exact !== false) {
+    if (!years || download?.rows_exact !== false) {
         return years;
     }
 
-    return download.window.start_year != null && download.window.end_year != null
-        ? `within ${years}`
-        : null;
+    return window?.start_year != null && window.end_year != null ? `within ${years}` : null;
 };
 
 /** One row of the panel's Details list. `source` names the provenance whose
@@ -2654,7 +2733,7 @@ export type DetailRow = {
  *  download has measured it, and the gaps in a broad answer, each open axis
  *  that some variables state no value for. The licence links to the page of
  *  the one source the answer serves. */
-export const detailRows = (spec: any, fileBytes: number | null = null): DetailRow[] => {
+export const detailRows = (spec: SpecReading, fileBytes: number | null = null): DetailRow[] => {
     const download = spec?.download;
     const rows: DetailRow[] = [];
     const years = detailYears(download);
@@ -2697,9 +2776,9 @@ export const detailRows = (spec: any, fileBytes: number | null = null): DetailRo
     }
 
     const gaps = (spec?.open_axis_facts ?? [])
-        .filter((fact: any) => fact?.distinct_count > 0 && fact.undeclared_count > 0)
+        .filter((fact) => fact?.distinct_count > 0 && fact.undeclared_count > 0)
         .map(
-            (fact: any) =>
+            (fact) =>
                 `${countNoun(fact.undeclared_count, 'variable')} ${
                     fact.undeclared_count === 1 ? 'states' : 'state'
                 } no ${axisLabel(spec, fact.property)}`,