@@ -257,3 +257,49 @@ export interface PathwayOfEntry {
   name?: Highlighted;
   hasEHLD?: boolean;
 }
+
+// -- The search answers -------------------------------------------------------
+//
+// Each takes its entry type as an argument: the service writes them with the
+// entries it builds, a reader reads them with the view it needs.
+
+/** One group of results: a type's, or "Results" for a search not grouped. */
+export interface ResultGroup<Entry> {
+  /** Left out when the group has none (an ungrouped search that found none). */
+  entries?: Entry[];
+  /** Left out for a group Solr names with nothing. */
+  typeName?: string;
+  /** How many Solr found. */
+  entriesCount: number;
+  /** How many are written here. */
+  rowCount: number;
+}
+
+/** A term the search found nothing for, and whether it names a resource; an empty term or resource is left out. */
+export interface TargetResult {
+  term?: string;
+  resource?: string | number | boolean;
+  target: boolean;
+}
+
+/** `/search/query`: the groups, the rows written, the groups and matches Solr counted. */
+export interface GroupedResult<Entry> {
+  results: ResultGroup<Entry>[];
+  rowCount: number;
+  numberOfGroups: number;
+  numberOfMatches: number;
+  /** For a search that found nothing: the terms, and whether each is a target. */
+  targetResults?: TargetResult[];
+}
+
+/** `/search/diagram/{id}` and `/search/fireworks`: the entries, their type facets, Solr's count. */
+export interface DiagramResult<Entry> {
+  /** Left out when there are none. */
+  entries?: Entry[];
+  /** Left out when there are none. */
+  facets?: FacetCount[];
+  found: number;
+}
+
+/** `/search/icon/query`: the icon library's page, one ungrouped group of icons. */
+export type IconResult = ResultGroup<IconEntry>;
@@ -1,3 +1,7 @@
-<a [href]="`${CONTENT_DETAIL}/${icon().id}`" target="_blank" [matTooltip]="`Open origin of icon ${icon().name}`">
+<a
+  [href]="`${CONTENT_DETAIL}/${icon().id}`"
+  target="_blank"
+  [matTooltip]="`Open origin of icon ${icon().iconName ?? icon().id}`"
+>
   <div [innerHTML]="iconSVG()! | safe: 'html' : true"></div>
 </a>
@@ -1,4 +1,11 @@
-import type { IconEntry, PathwayOfEntry, SearchEntryView } from '../../../../contract/search.ts';
+import type {
+  DiagramResult,
+  FacetCount,
+  GroupedResult,
+  IconEntry,
+  PathwayOfEntry,
+  SearchEntryView,
+} from '../../../../contract/search.ts';
 
 export namespace Search {
   export const EMPTY_RESULTS = { found: 0, facets: [], entries: [] } as Search.Result;
@@ -21,17 +28,9 @@ export namespace Search {
   export type Entry = SearchEntryView;
   export type PathwayOf = PathwayOfEntry;
 
-  export interface Facet {
-    name: string;
-    count: number;
-  }
-
-  // firework and diagram
-  export interface Result {
-    entries: Entry[];
-    facets: Facet[];
-    found: number;
-  }
+  // A diagram's or the species overview's search: the contract's (spec 016).
+  export type Facet = FacetCount;
+  export type Result = DiagramResult<Entry>;
 
   // Add a sub-namespace for Icon-specific results
   export namespace Icon {
@@ -40,18 +39,6 @@ export namespace Search {
 
     // A query for icons answers whatever its groups hold: a query matching
     // no icon answers proteins, compounds and the like, any kind.
-    export interface EntryResult {
-      entries: Search.Entry[];
-      typeName: string;
-      entriesCount: number;
-      rowCount: number;
-    }
-
-    export interface Result {
-      results: EntryResult[];
-      rowCount: number;
-      numberOfGroups: number;
-      numberOfMatches: number;
-    }
+    export type Result = GroupedResult<Search.Entry>;
   }
 }
@@ -268,7 +268,7 @@ export class IconService {
         // No result group at all is no icon, not an error.
         map((response) => {
           const [group] = response.results;
-          const [entry] = group?.typeName === 'Icon' ? group.entries : [];
+          const [entry] = group?.typeName === 'Icon' ? (group.entries ?? []) : [];
           return entry && isIcon(entry) ? entry : null;
         }),
         switchMap((entry) => {
 
@@ -396,7 +396,13 @@ export class SearchComponent {
 // TODO find a way to avoid the break in scroll when loading a new page
 export class SearchDataSource extends DataSource<Search.Entry | undefined> {
   private readonly _result = signal<Search.Result | undefined>(undefined);
-  readonly facets = computed(() => this._result()?.facets || []);
+  // A count Solr gives under no name is written without one: nothing to show
+  // or filter by, as on the site's search page.
+  readonly facets = computed(() =>
+    (this._result()?.facets || []).filter(
+      (facet): facet is Search.Facet & { name: string } => !!facet.name
+    )
+  );
   readonly found = computed(() => this._result()?.found || 0);
   readonly isLoading = signal<boolean>(false);
   /** Pages that could not be loaded, until asked for again. */
@@ -484,7 +490,7 @@ export class SearchDataSource extends DataSource<Search.Entry | undefined> {
           if (!current()) return;
           this._result.set(result);
           if (this.cachedEntries.length !== result.found) this.cachedEntries.length = result.found;
-          this.cachedEntries.splice(page * this.pageSize, this.pageSize, ...result.entries);
+          this.cachedEntries.splice(page * this.pageSize, this.pageSize, ...(result.entries ?? []));
           this.dataStream.next(this.cachedEntries);
           markFailed(false);
           this.isLoading.set(false);
 
@@ -122,7 +122,7 @@ export class InteractorDetailComponent implements OnInit {
         // The first hit that is a reference: when nothing matches as an
         // interactor the search answers unfiltered, and an Icon can lead.
         const entry = search?.results
-          .flatMap((group) => group.entries)
+          .flatMap((group) => group.entries ?? [])
           .find((hit) => hit.databaseName && hit.referenceIdentifier);
         if (entry) {
           // The search is highlighted: an identifier or name that matched
 
@@ -5,7 +5,8 @@ import {
   SearchFilters,
   Facet,
   NamedFacetCount,
-  ResultGroup,
+  ShownGroup,
+  ShownResult,
 } from '../../model/search.model';
 import {
   Component,
@@ -108,7 +109,7 @@ export class SearchComponent implements OnInit, OnDestroy {
     this.cdr.markForCheck();
   }
   suggestedTerms: string[] = [];
-  results: SearchResult | null = null;
+  results: ShownResult | null = null;
   facets: FacetResponse | null = null;
   loading = false;
   error = '';
@@ -310,7 +311,15 @@ export class SearchComponent implements OnInit, OnDestroy {
           this.hasNoResults = false;
         } else {
           // Successful API response - check if we have results
-          const res = results as SearchResult;
+          const answer = results as SearchResult;
+          const res: ShownResult = {
+            ...answer,
+            results: answer.results.map((group) => ({
+              ...group,
+              entries: group.entries ?? [],
+              typeName: group.typeName ?? '',
+            })),
+          };
           // Solr's true total across the whole result set; per-group
           // pagination chops each `group.entries` down to ~30, so we
           // must NOT recompute this from entries.length later.
@@ -391,7 +400,7 @@ export class SearchComponent implements OnInit, OnDestroy {
                 typeName: 'Pages',
                 entries: pageEntries,
                 entriesCount: pageEntries.length,
-              } as ResultGroup,
+              } as ShownGroup,
             ];
           }
           // Keep Solr's biology total; add Pages count (when shown); zero
@@ -445,6 +454,7 @@ export class SearchComponent implements OnInit, OnDestroy {
       return of({
         results: [],
         rowCount: 0,
+        numberOfGroups: 0,
         numberOfMatches: 0,
       });
     }
@@ -479,7 +489,7 @@ export class SearchComponent implements OnInit, OnDestroy {
       for (const result of results) {
         if (!result?.results.length) continue;
         const group = result.results.find((g) => g.typeName === 'Protein');
-        if (group) allProteins.push(...group.entries);
+        if (group) allProteins.push(...(group.entries ?? []));
       }
 
       // Group by referenceIdentifier, else the entry's own id (its stId, or
@@ -700,18 +710,18 @@ export class SearchComponent implements OnInit, OnDestroy {
   }
 
   // Per-group pagination
-  getGroupPage(group: ResultGroup): number {
+  getGroupPage(group: ShownGroup): number {
     return this.groupPages[group.typeName] || 0;
   }
 
-  getGroupTotalPages(group: ResultGroup): number {
+  getGroupTotalPages(group: ShownGroup): number {
     if (group.typeName === 'Protein') {
       return Math.ceil(this.uniqueProteins.length / this.groupPageSize) || 1;
     }
     return Math.ceil(group.entriesCount / this.groupPageSize);
   }
 
-  getGroupPageEntries(group: ResultGroup): SearchEntry[] {
+  getGroupPageEntries(group: ShownGroup): SearchEntry[] {
     if (group.typeName === 'Protein') {
       // While still loading all proteins, show nothing (loading message is displayed)
       if (this.proteinLoading) return [];
@@ -726,7 +736,7 @@ export class SearchComponent implements OnInit, OnDestroy {
     return this.groupPageEntries[group.typeName] || group.entries.slice(0, this.groupPageSize);
   }
 
-  goToGroupPage(group: ResultGroup, page: number): void {
+  goToGroupPage(group: ShownGroup, page: number): void {
     const total = this.getGroupTotalPages(group);
     if (page < 0 || page >= total) return;
 
@@ -760,7 +770,7 @@ export class SearchComponent implements OnInit, OnDestroy {
       });
   }
 
-  getGroupPageNumbers(group: ResultGroup): (number | '...')[] {
+  getGroupPageNumbers(group: ShownGroup): (number | '...')[] {
     return this.buildPageNumbers(this.getGroupPage(group), this.getGroupTotalPages(group));
   }
 
 
@@ -2,10 +2,5 @@ export type { IconCategory, IconFacetResponse } from '../../../contract/search.t
 
 // One icon: the contract's (spec 016).
 export type { IconEntry } from '../../../contract/search.ts';
-import type { IconEntry } from '../../../contract/search.ts';
 
-export interface IconResult {
-  /** Left out when nothing matches. */
-  entries?: IconEntry[];
-  entriesCount: number;
-}
+export type { IconResult } from '../../../contract/search.ts';
@@ -6,18 +6,19 @@
 export type { SearchEntryView as SearchEntry } from '../../../contract/search.ts';
 import type { SearchEntryView } from '../../../contract/search.ts';
 
-export interface ResultGroup {
-  typeName: string;
-  entries: SearchEntryView[];
-  entriesCount: number;
-  rowCount: number;
-}
+// A search's answer, as the contract has it, with the view's entries.
+import type { GroupedResult, ResultGroup as Group } from '../../../contract/search.ts';
+type ResultGroup = Group<SearchEntryView>;
+export type SearchResult = GroupedResult<SearchEntryView>;
 
-export interface SearchResult {
-  results: ResultGroup[];
-  rowCount: number;
-  numberOfMatches: number;
-}
+/**
+ * A group as the search page keeps it: its entries and name settled when the
+ * answer arrives, an absent list as none and an absent name as empty text.
+ * The answer leaves both out at times (an ungrouped page past the end, a
+ * group Solr names with nothing); the page reads them everywhere.
+ */
+export type ShownGroup = ResultGroup & Required<Pick<ResultGroup, 'entries' | 'typeName'>>;
+export type ShownResult = Omit<SearchResult, 'results'> & { results: ShownGroup[] };
 
 export type { Facet, FacetResponse, NamedFacetCount } from '../../../contract/search.ts';
 
 
@@ -60,7 +60,7 @@ description: 'Tasks for spec 016: one API contract for the content service and t
 - [x] T010 [US2] Make the site's `SearchEntry` and `IconEntry` re-export the contract's, and narrow by kind where `search.component.ts`, `interactor-detail.component.ts`, `icon-lib.component.ts` and `icon-detail.component.ts` read kind-specific fields.
   - Escape or render `Highlighted` fields as each reader does today, with no change visible on the page.
   - Check the search page and an icon page in a browser.
-  - Done in #691. The site's `SearchEntry` is the contract's `SearchEntryView`: any kind, what every kind carries required, the rest optional (FR-003's view, since the search page shows every kind side by side and a template cannot read a field one kind lacks); `IconEntry` is the contract's kind. Two readers changed: the protein forms' key drops a fallback `id` already covers (`id` is the stId, or the dbId, never empty), and an icon's image is found by `id`, the same value as `stId` but never highlighted. From #690's review, the icon library too (#691): its search is highlighted, and asking beta's service for `R-ICO-012449` there answers `stId` as `<span class="highlighting" >R-ICO-012449</span>`, `id` plain, so its image, link, fetch and shown id were built from markup; they take `id` now, as does the pathway browser's icon load. From #691's review (#697): the search page printed a highlighted reference identifier as text, `PTEN (<span class="highlighting" >P60484</span>)` for a search of P60484, seen in the browser against beta's services; it is rendered as its neighbours are (`[innerHTML]`) and reads `PTEN (P60484)`. An icon's alt text and the pathway browser's icon link take `id`, and the interactor page strips a highlighted name as it strips the identifier. Nothing else visible changes; the search, search-error and icon-library end-to-end specs pass (46 and 78 tests with the specs below). The single icon page reads only type changes; no recording opens one (the `gap` T014 closes).
+  - Done in #691. The site's `SearchEntry` is the contract's `SearchEntryView`: any kind, what every kind carries required, the rest optional (FR-003's view, since the search page shows every kind side by side and a template cannot read a field one kind lacks); `IconEntry` is the contract's kind. Two readers changed: the protein forms' key drops a fallback `id` already covers (`id` is the stId, or the dbId, never empty), and an icon's image is found by `id`, the same value as `stId` but never highlighted. From #690's review, the icon library too (#691): its search is highlighted, and asking beta's service for `R-ICO-012449` there answers `stId` as `<span class="highlighting" >R-ICO-012449</span>`, `id` plain, so its image, link, fetch and shown id were built from markup; they take `id` now, as does the pathway browser's icon load. From #691's review (#697): the search page printed a highlighted reference identifier as text, `PTEN (<span class="highlighting" >P60484</span>)` for a search of P60484, seen in the browser against beta's services; it is rendered as its neighbours are (`[innerHTML]`) and reads `PTEN (P60484)`. An icon's alt text and the pathway browser's icon link take `id`, and the interactor page strips a highlighted name as it strips the identifier. Nothing else visible changes; the search, search-error and icon-library end-to-end specs passed for #691 (46 and 78 tests with the specs below). The single icon page reads only type changes; no recording opens one (the `gap` T014 closes).
 - [x] T011 [US2] Make the pathway browser's `Search.Entry` and `Search.Icon.Entry` re-export the contract's, keeping the value `EMPTY_RESULTS` in the namespace. Adjust `viewport/search/search.component.ts`, `services/icon.service.ts` and `details/tabs/description-tab/icon/icon.component.ts`, and check the diagram search in a browser.
   - Done in #691. `Search.Entry` is the view, `Search.Icon.Entry` the icon kind, and an icon query's groups hold any kind (three of the five recorded answers are proteins, compounds or drugs), so `fetchIcon` takes an entry only when it is an icon, not deleted, besides its group's name. Its unit spec's icon is now one as the search writes it, and a deleted icon in an icon group gives none (failing without the check). The flag button takes `id`. The in-diagram search, flagging, pathway-browser, entity popup, structures and pathway-data specs pass; their recordings answer the icon query with icons (R-ICO-013990, R-ICO-012536) and with other kinds.
 - [x] T012 [US2] Recount `tools/api-types/known-problems.json`. Record what remains on the search routes, each item with its reason, in this task's PR and here.
@@ -72,7 +72,8 @@ description: 'Tasks for spec 016: one API contract for the content service and t
 
 **Independent test**: every search route's known problems are at zero or explained.
 
-- [ ] T013 [US3] Write `ResultGroup<E>`, `GroupedResult` (with `numberOfGroups`), the diagram and species-overview result types and `IconResult` (with `rowCount` and `typeName`) in `projects/contract/search.ts`, and point their writers in `search-endpoints.ts` and `search-diagram-endpoints.ts`, and their readers, at them.
+- [x] T013 [US3] Write `ResultGroup<E>`, `GroupedResult` (with `numberOfGroups`), the diagram and species-overview result types and `IconResult` (with `rowCount` and `typeName`) in `projects/contract/search.ts`, and point their writers in `search-endpoints.ts` and `search-diagram-endpoints.ts`, and their readers, at them.
+  - Done in #703. The contract's `ResultGroup<Entry>`, `GroupedResult<Entry>`, `DiagramResult<Entry>`, `TargetResult` and `IconResult`, each taking its entry type as a named argument: the service writes them with its `WrittenEntry`, a reader reads them with the view. A group's `entries` is optional (an ungrouped page past the end has none) and so is its `typeName` (a group Solr names with nothing); the search page settles both once when the answer arrives (`ShownGroup`), and the pathway browser's search shows only named type facets, as the site's does. A target's empty term or resource is left out, so both are optional. A grouping without `matches` is skipped, as SolrJ's `QueryResponse.extractGroupedInfo` skips it (read from its bytecode, from #700's review): the first grouping that has its matches is read, and none is no result, Java's 500 (a spec of two groupings, the first without matches, fails on the first-grouping reading). The search routes' known problems are 0, the whole 12,164. From #697's review, the pathway browser's icon tooltip takes `iconName`, never highlighted.
 - [ ] T014 [US3] Record an answer for `/search/icon/{id}` (already in `tools/api-types/calls.ts` as `IconEntry`, with a `gap`) through the e2e suite and remove the `gap` (record rewrites three HARs: check the diff). Type its writer.
 - [ ] T015 [US3] Tick spec 013 T019 in `specs/013-server-types/tasks.md` with T002–T014's PR numbers.