diff --git a/src/components/documents/document-detail-sheet.tsx b/src/components/documents/document-detail-sheet.tsx
new file mode 100644
index 000000000..e376ba082
--- /dev/null
+++ b/src/components/documents/document-detail-sheet.tsx
@@ -0,0 +1,463 @@
+"use client";
+
+/**
+ * Document detail on `ResponsiveSheet` (bottom sheet on phones, dialog on
+ * desktop). Inline-class documents (PDF / browser-native images) preview
+ * inline against the owner-scoped decrypt-and-serve route — skeleton first,
+ * content on load, internal scroll only (`overscroll-contain`). Attachment-
+ * class documents get NO fake preview: type glyph, filename, size, and a
+ * prominent Download button.
+ *
+ * Metadata edits save on commit (title on Enter/blur, kind and filing date
+ * on change, condition links on toggle — replace-set PATCH). Mutation
+ * errors surface inline (`role="alert"`), never as a QueryErrorCard.
+ * Delete soft-deletes with an Undo toast (restore endpoint); a restore
+ * refusal maps `meta.reason` (`purged`, `duplicateExists`) to translated
+ * copy. No share affordance anywhere — deliberately.
+ */
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { Check, Download, Pencil, Plus, Trash2 } from "lucide-react";
+import Link from "next/link";
+import { useState } from "react";
+import { toast } from "sonner";
+
+import { useIllnessEpisodes } from "@/components/illness/use-illness";
+import { Button } from "@/components/ui/button";
+import { DateField } from "@/components/ui/date-field";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import {
+  Popover,
+  PopoverContent,
+  PopoverTrigger,
+} from "@/components/ui/popover";
+import { ResponsiveSheet } from "@/components/ui/responsive-sheet";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
+import { Skeleton } from "@/components/ui/skeleton";
+import {
+  apiDelete,
+  ApiError,
+  apiGet,
+  apiPatch,
+  apiPost,
+} from "@/lib/api/api-fetch";
+import { useFormatters, useTranslations } from "@/lib/i18n/context";
+import { invalidateKeys, queryKeys } from "@/lib/query-keys";
+import { cn } from "@/lib/utils";
+import {
+  INBOUND_DOCUMENT_KINDS,
+  type InboundDocumentDetailDto,
+  type InboundDocumentKindValue,
+} from "@/lib/validations/inbound-documents";
+import { DOCUMENT_KIND_ICONS } from "./document-kind-meta";
+import { formatBytes } from "./vault-utils";
+
+type PatchInput = {
+  title?: string | null;
+  kind?: InboundDocumentKindValue;
+  documentDate?: string | null;
+  episodeIds?: string[];
+};
+
+/** Inline preview for Class A documents; skeleton until the blob paints. */
+function InlinePreview({
+  documentId,
+  mimeType,
+  title,
+}: {
+  documentId: string;
+  mimeType: string;
+  title: string;
+}) {
+  const [loaded, setLoaded] = useState(false);
+  const src = `/api/documents/inbound/${documentId}/original`;
+  const isPdf = mimeType === "application/pdf";
+
+  return (
+    <div className="relative max-h-[55vh] overflow-auto overscroll-contain rounded-lg">
+      {!loaded ? (
+        <Skeleton
+          className={cn("w-full rounded-lg", isPdf ? "h-[55vh]" : "h-64")}
+        />
+      ) : null}
+      {isPdf ? (
+        <iframe
+          src={src}
+          title={title}
+          sandbox=""
+          onLoad={() => setLoaded(true)}
+          className={cn(
+            "border-border h-[55vh] w-full rounded-lg border",
+            !loaded && "absolute inset-0 opacity-0",
+          )}
+        />
+      ) : (
+        // Decrypted same-origin blob stream: next/image cannot optimise it
+        // and would only proxy the bytes through a second request.
+        // eslint-disable-next-line @next/next/no-img-element
+        <img
+          src={src}
+          alt={title}
+          onLoad={() => setLoaded(true)}
+          className={cn(
+            "mx-auto max-h-[55vh] w-auto max-w-full rounded-lg object-contain",
+            !loaded && "absolute inset-0 opacity-0",
+          )}
+        />
+      )}
+    </div>
+  );
+}
+
+export function DocumentDetailSheet({
+  documentId,
+  open,
+  onOpenChange,
+}: {
+  documentId: string | null;
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+}) {
+  const { t, locale } = useTranslations();
+  const format = useFormatters();
+  const queryClient = useQueryClient();
+
+  const detail = useQuery({
+    queryKey: queryKeys.inboundDocument(documentId ?? "none"),
+    enabled: open && documentId !== null,
+    queryFn: () =>
+      apiGet<InboundDocumentDetailDto>(`/api/documents/inbound/${documentId}`),
+  });
+  const doc = detail.data;
+
+  const episodes = useIllnessEpisodes(true);
+
+  const [mutationError, setMutationError] = useState<string | null>(null);
+  const [editingTitle, setEditingTitle] = useState(false);
+  const [titleDraft, setTitleDraft] = useState("");
+
+  // Reset transient edit state whenever another document opens —
+  // render-phase derived-state adjustment, not an effect.
+  const [lastDocumentId, setLastDocumentId] = useState(documentId);
+  if (lastDocumentId !== documentId) {
+    setLastDocumentId(documentId);
+    setEditingTitle(false);
+    setMutationError(null);
+  }
+
+  const patch = useMutation({
+    mutationFn: (input: PatchInput) =>
+      apiPatch<InboundDocumentDetailDto>(
+        `/api/documents/inbound/${documentId}`,
+        input,
+      ),
+    onSuccess: () => {
+      setMutationError(null);
+      void invalidateKeys(queryClient, [queryKeys.documents()]);
+    },
+    onError: () => setMutationError(t("documents.detail.saveError")),
+  });
+
+  const restore = useMutation({
+    mutationFn: (id: string) =>
+      apiPost(`/api/documents/inbound/${id}/restore`, {}),
+    onSuccess: () => {
+      void invalidateKeys(queryClient, [queryKeys.documents()]);
+    },
+    onError: (error) => {
+      const reason =
+        error instanceof ApiError && typeof error.meta?.reason === "string"
+          ? error.meta.reason
+          : "";
+      if (reason === "purged") {
+        toast.error(t("documents.error.purged"));
+      } else if (reason === "duplicateExists") {
+        toast.error(t("documents.error.duplicateExists"));
+      } else {
+        toast.error(t("documents.toast.restoreFailed"));
+      }
+    },
+  });
+
+  const remove = useMutation({
+    mutationFn: (id: string) => apiDelete(`/api/documents/inbound/${id}`),
+    onSuccess: (_data, id) => {
+      onOpenChange(false);
+      void invalidateKeys(queryClient, [queryKeys.documents()]);
+      toast.success(t("documents.toast.deleted"), {
+        action: {
+          label: t("common.undo"),
+          onClick: () => restore.mutate(id),
+        },
+      });
+    },
+    onError: () => setMutationError(t("documents.detail.deleteError")),
+  });
+
+  const commitTitle = () => {
+    if (!doc) return;
+    setEditingTitle(false);
+    const next = titleDraft.trim();
+    const current = doc.title ?? "";
+    if (next === current) return;
+    patch.mutate({ title: next === "" ? null : next });
+  };
+
+  const toggleEpisode = (episodeId: string) => {
+    if (!doc) return;
+    const current = doc.conditionLinks.map((l) => l.episodeId);
+    const next = current.includes(episodeId)
+      ? current.filter((id) => id !== episodeId)
+      : [...current, episodeId];
+    patch.mutate({ episodeIds: next });
+  };
+
+  const title = doc?.title ?? doc?.filename ?? t("documents.card.untitled");
+  const Icon = doc ? DOCUMENT_KIND_ICONS[doc.kind] : null;
+  const originalHref = doc ? `/api/documents/inbound/${doc.id}/original` : "#";
+
+  return (
+    <ResponsiveSheet
+      open={open}
+      onOpenChange={onOpenChange}
+      title={title}
+      description={t("documents.detail.title")}
+      contentWidth="3xl"
+      footer={
+        doc ? (
+          <>
+            <Button variant="outline" asChild data-slot="document-download">
+              <a href={originalHref} download={doc.filename ?? undefined}>
+                <Download className="size-4" aria-hidden />
+                {t("documents.detail.download")}
+              </a>
+            </Button>
+            <Button
+              variant="destructive"
+              onClick={() => remove.mutate(doc.id)}
+              disabled={remove.isPending}
+            >
+              <Trash2 className="size-4" aria-hidden />
+              {t("documents.detail.delete")}
+            </Button>
+          </>
+        ) : undefined
+      }
+    >
+      {detail.isPending && open ? (
+        <div className="space-y-3" data-slot="document-detail-loading">
+          <Skeleton className="h-48 w-full rounded-lg" />
+          <Skeleton className="h-9 w-2/3" />
+          <Skeleton className="h-9 w-1/2" />
+        </div>
+      ) : null}
+
+      {detail.isError ? (
+        <p role="alert" className="text-destructive text-sm">
+          {t("documents.detail.loadError")}
+        </p>
+      ) : null}
+
+      {doc ? (
+        <div className="space-y-6">
+          {doc.servingClass === "inline" ? (
+            <InlinePreview
+              documentId={doc.id}
+              mimeType={doc.mimeType}
+              title={title}
+            />
+          ) : (
+            <div className="border-border flex flex-col items-center gap-2 rounded-lg border px-4 py-8 text-center">
+              {Icon ? (
+                <Icon className="text-muted-foreground size-8" aria-hidden />
+              ) : null}
+              <p className="max-w-full truncate text-sm font-medium">
+                {doc.filename ?? title}
+              </p>
+              <p className="text-muted-foreground text-xs">
+                {t("documents.detail.previewUnavailable")} ·{" "}
+                {formatBytes(doc.byteSize, locale)}
+              </p>
+              <Button asChild size="sm" className="mt-1">
+                <a href={originalHref} download={doc.filename ?? undefined}>
+                  <Download className="size-4" aria-hidden />
+                  {t("documents.detail.download")}
+                </a>
+              </Button>
+            </div>
+          )}
+
+          {mutationError ? (
+            <p role="alert" className="text-destructive text-sm">
+              {mutationError}
+            </p>
+          ) : null}
+
+          <div className="space-y-4">
+            <div className="space-y-1.5">
+              <Label htmlFor="document-title-input">
+                {t("documents.detail.titleLabel")}
+              </Label>
+              {editingTitle ? (
+                <Input
+                  id="document-title-input"
+                  autoFocus
+                  value={titleDraft}
+                  onChange={(e) => setTitleDraft(e.target.value)}
+                  onBlur={commitTitle}
+                  onKeyDown={(e) => {
+                    if (e.key === "Enter") commitTitle();
+                    if (e.key === "Escape") setEditingTitle(false);
+                  }}
+                  maxLength={200}
+                  placeholder={t("documents.detail.titlePlaceholder")}
+                />
+              ) : (
+                <button
+                  type="button"
+                  id="document-title-input"
+                  onClick={() => {
+                    setTitleDraft(doc.title ?? "");
+                    setEditingTitle(true);
+                  }}
+                  className="border-input hover:bg-muted/50 focus-visible:ring-ring/50 flex min-h-10 w-full items-center justify-between gap-2 rounded-md border px-3 py-2 text-left text-sm focus-visible:ring-[3px] focus-visible:outline-none"
+                >
+                  <span
+                    className={cn(
+                      "truncate",
+                      doc.title === null && "text-muted-foreground",
+                    )}
+                  >
+                    {doc.title ?? t("documents.detail.titlePlaceholder")}
+                  </span>
+                  <Pencil
+                    className="text-muted-foreground size-3.5 shrink-0"
+                    aria-hidden
+                  />
+                </button>
+              )}
+            </div>
+
+            <div className="grid gap-4 sm:grid-cols-2">
+              <div className="space-y-1.5">
+                <Label htmlFor="document-kind-select">
+                  {t("documents.detail.kindLabel")}
+                </Label>
+                <Select
+                  value={doc.kind}
+                  onValueChange={(value) =>
+                    patch.mutate({ kind: value as InboundDocumentKindValue })
+                  }
+                >
+                  <SelectTrigger id="document-kind-select" className="w-full">
+                    <SelectValue />
+                  </SelectTrigger>
+                  <SelectContent>
+                    {INBOUND_DOCUMENT_KINDS.map((kind) => (
+                      <SelectItem key={kind} value={kind}>
+                        {t(`documents.kind.${kind}`)}
+                      </SelectItem>
+                    ))}
+                  </SelectContent>
+                </Select>
+              </div>
+              <div className="space-y-1.5">
+                <Label htmlFor="document-date-field">
+                  {t("documents.detail.dateLabel")}
+                </Label>
+                <DateField
+                  id="document-date-field"
+                  value={doc.documentDate ?? ""}
+                  onChange={(value) =>
+                    patch.mutate({ documentDate: value === "" ? null : value })
+                  }
+                  aria-label={t("documents.detail.dateLabel")}
+                />
+              </div>
+            </div>
+
+            <div className="space-y-1.5">
+              <p className="text-sm leading-none font-medium">
+                {t("documents.detail.conditionsLabel")}
+              </p>
+              <div className="flex flex-wrap items-center gap-1.5">
+                {doc.conditionLinks.map((link) => (
+                  <Link
+                    key={link.episodeId}
+                    href={`/illness/${link.episodeId}`}
+                    className="bg-muted text-foreground hover:bg-muted/70 focus-visible:ring-ring/50 inline-flex max-w-48 items-center rounded-full px-2.5 py-1 text-xs focus-visible:ring-[3px] focus-visible:outline-none"
+                  >
+                    <span className="truncate">{link.name}</span>
+                  </Link>
+                ))}
+                {doc.conditionLinks.length === 0 ? (
+                  <span className="text-muted-foreground text-xs">
+                    {t("documents.detail.noConditions")}
+                  </span>
+                ) : null}
+                {(episodes.data?.length ?? 0) > 0 ? (
+                  <Popover>
+                    <PopoverTrigger asChild>
+                      <Button
+                        variant="outline"
+                        size="sm"
+                        className="h-7 rounded-full px-2.5 text-xs"
+                      >
+                        <Plus className="size-3" aria-hidden />
+                        {t("documents.detail.linkCondition")}
+                      </Button>
+                    </PopoverTrigger>
+                    <PopoverContent align="start" className="w-64 p-2">
+                      <ul className="max-h-56 space-y-0.5 overflow-y-auto overscroll-contain">
+                        {episodes.data?.map((episode) => {
+                          const linked = doc.conditionLinks.some(
+                            (l) => l.episodeId === episode.id,
+                          );
+                          return (
+                            <li key={episode.id}>
+                              <button
+                                type="button"
+                                onClick={() => toggleEpisode(episode.id)}
+                                className="hover:bg-muted focus-visible:ring-ring/50 flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left text-sm focus-visible:ring-[3px] focus-visible:outline-none"
+                                aria-pressed={linked}
+                              >
+                                <Check
+                                  className={cn(
+                                    "size-4 shrink-0",
+                                    linked ? "opacity-100" : "opacity-0",
+                                  )}
+                                  aria-hidden
+                                />
+                                <span className="truncate">
+                                  {episode.label}
+                                </span>
+                              </button>
+                            </li>
+                          );
+                        })}
+                      </ul>
+                    </PopoverContent>
+                  </Popover>
+                ) : null}
+              </div>
+            </div>
+
+            <p className="text-muted-foreground text-xs">
+              {t("documents.detail.uploadedMeta", {
+                date: format.date(doc.createdAt),
+                size: formatBytes(doc.byteSize, locale),
+              })}
+              {doc.filename ? ` · ${doc.filename}` : ""}
+            </p>
+          </div>
+        </div>
+      ) : null}
+    </ResponsiveSheet>
+  );
+}