Phase 3c: Compose view with chair-position editor

New /cases/[caseNumber]/compose route ports the research analysis +
chair-position editing flow from the vanilla UI onto the Next.js
stack. Reads /api/cases/{n}/research/analysis, renders background
prose in the side column and threshold claims + issues as collapsible
cards in the main column, each with a blur-autosaved chair editor
wired through a TanStack Query mutation with optimistic cache patching
(so concurrent reads don't steal editor focus).

Handles the common "analysis not yet generated" 404 with a dedicated
empty state rather than an error card.

Phase 3 task 85 is now ready for review end-to-end.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/src/lib/api/research.ts

@@ -0,0 +1,95 @@
+/**
+ * Research analysis hooks — reads and mutates the
+ * `analysis-and-research.md` file that backs each case's compose screen.
+ *
+ * Schema mirrors research_md.parse() in the FastAPI backend. Kept as
+ * hand-typed interfaces because the endpoint does not declare a
+ * response_model in the OpenAPI schema.
+ */
+
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { apiRequest } from "./client";
+
+export type ResearchField = {
+  label: string;
+  content: string;
+};
+
+export type ResearchSubsection = {
+  id: string; // e.g. "threshold_1" or "issue_3"
+  number: string;
+  title: string;
+  fields: ResearchField[];
+  chair_position?: string;
+};
+
+export type ResearchAnalysis = {
+  header?: {
+    date?: string;
+    modified_at?: string;
+    [k: string]: unknown;
+  };
+  represented_party?: string;
+  procedural_background?: string;
+  agreed_facts?: string;
+  disputed_facts?: string;
+  threshold_claims?: ResearchSubsection[];
+  issues?: ResearchSubsection[];
+  conclusions?: string;
+  other_sections?: Array<{ title: string; body: string }>;
+};
+
+export const researchKeys = {
+  all: ["research"] as const,
+  analysis: (caseNumber: string) =>
+    [...researchKeys.all, "analysis", caseNumber] as const,
+};
+
+export function useResearchAnalysis(caseNumber: string | undefined) {
+  return useQuery({
+    queryKey: researchKeys.analysis(caseNumber ?? ""),
+    queryFn: ({ signal }) =>
+      apiRequest<ResearchAnalysis>(
+        `/api/cases/${caseNumber}/research/analysis`,
+        { signal },
+      ),
+    enabled: Boolean(caseNumber),
+    /* No polling — the user is editing; refetching would clobber focus */
+    staleTime: 60_000,
+  });
+}
+
+export function useSaveChairPosition(caseNumber: string | undefined) {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: async (vars: { sectionId: string; position: string }) =>
+      apiRequest<unknown>(
+        `/api/cases/${caseNumber}/research/analysis/chair-position`,
+        {
+          method: "PATCH",
+          body: { section_id: vars.sectionId, position: vars.position },
+        },
+      ),
+    onSuccess: (_res, vars) => {
+      /* Locally patch the cached analysis so other consumers stay in sync
+         without an immediate refetch that would steal focus from the editor. */
+      qc.setQueryData<ResearchAnalysis | undefined>(
+        researchKeys.analysis(caseNumber ?? ""),
+        (prev) => {
+          if (!prev) return prev;
+          const patch = (arr?: ResearchSubsection[]) =>
+            arr?.map((s) =>
+              s.id === vars.sectionId
+                ? { ...s, chair_position: vars.position }
+                : s,
+            );
+          return {
+            ...prev,
+            threshold_claims: patch(prev.threshold_claims),
+            issues: patch(prev.issues),
+          };
+        },
+      );
+    },
+  });
+}