diff --git a/CHUNK#4.md b/CHUNK#4.md
index 3cfee75..61ece4f 100644
--- a/CHUNK#4.md
+++ b/CHUNK#4.md
@@ -4,6 +4,8 @@
 
 **Purpose:** Make the story's moving parts first-class: character sheets with typed relationships, flexible world items, fast fuzzy search, backlinks, and `@mention` links from prose to entities. After this chunk, the "tools to facilitate and integrate characters, world building" requirement is fully delivered.
 
+**Status (updated 2026-10-25):** 🟡 In progress. Data layer and entity UI layer complete and CI-green (`pnpm typecheck`, `pnpm test`, `pnpm lint`, `pnpm build` all pass; 65 tests green across the workspace). See "Remaining" below.
+
 ---
 
 ## Steps
@@ -40,14 +42,22 @@
 ---
 
 ## Acceptance criteria (all must pass)
-- [ ] Create a character with all field types (incl. list + link) via the generic renderer — no custom code added.
-- [ ] Fuzzy search over 500 seeded entities returns in < 50 ms (measured in test).
-- [ ] `@` autocomplete → chip → popover → open sheet, all working; works while typing fast (no stale menus).
-- [ ] Backlinks correct and live-updating (save doc → "Appears in" updates within one event round-trip).
-- [ ] Consistency check flags the seeded dead-character-after-death case.
-- [ ] Relationship map renders and navigates.
+- [~] Create a character with all field types (incl. list + link) via the generic renderer — no custom code added. Generic renderer done for `text`/`textarea`/`checkbox`/`tags` (list); `link` field type pending.
+- [x] Fuzzy search over 500 seeded entities returns in < 50 ms (measured in test).
+- [~] `@` autocomplete → chip → popover → open sheet, all working; works while typing fast (no stale menus). Autocomplete + chip + open sheet done; hover popover pending.
+- [x] Backlinks correct and live-updating (save doc → "Appears in" updates within one event round-trip).
+- [ ] Consistency check flags the seeded dead-character-after-death case. Logic in `packages/core/src/consistency.ts` done; UI wiring + seeded case pending.
+- [x] Relationship map renders and navigates.
 - [ ] Global palette finds a chapter, a character, and a note from one box.
-- [ ] Contract suite still green on both adapters.
+- [x] Contract suite still green on both adapters.
+
+## Remaining work
+- Wire `findInconsistencies()` into the Characters tab as a warnings list (Chunk 3.2).
+- Index entities in the global `Ctrl/Cmd+K` palette (Chunk 3.1).
+- Context rail (right side of WritingView): this chapter's mentioned characters, pinned entities, related notes (Chunk 3.2).
+- Extend `server/src/seed.ts`: full character sheets (bio, voice, 2 relationships each) + 5 world items (Chunk 4.1).
+- `docs/DATA_MODEL.md`: the entity registry table (kind → fields) as the human reference (Chunk 4.2).
+- E2E: create character → `@mention` it in a chapter → backlinks tab lists the chapter → open sheet from the chip (Chunk 5.3).
 
 ## Definition of done
 The author's canon — who, what, where — is structured, searchable, linked to the prose, and checkable. This is the data the AI roles will reason from in Chunk 9.
diff --git a/PLAN.md b/PLAN.md
index c51ed0f..2351925 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -270,7 +270,7 @@ Each chunk is a 1–3 day work order in `CHUNK#n.md`, written so a human *or* a
 | 1 | **Scaffold & Foundations** | 1 | ✅ Done | Monorepo, strict TS, tooling, app shell, theme system, CI, settings store |
 | 2 | **Data Model, Storage & Auth** | 3 | ⬜ Not started | Full domain types, StorageAdapter, Local + Server adapters, Fastify auth/multi-tenant, autosave, contract tests |
 | 3 | **Writing Surface** | 3 | 🟡 In progress | TipTap editor ✅, document tree ✅, focus mode ✅, Markdown I/O ✅, autosave ✅, writing view wired to storage adapter ✅ (UI-disappears crash fixed), fonts/logo polish 🟡 |
-| 4 | **Characters & World-Building** | 2 | ⬜ Not started | Entity schema, character sheets, world items, search, mentions, backlinks |
+| 4 | **Characters & World-Building** | 2 | 🟡 In progress | Entity schema ✅, character sheets ✅, world items ✅, fuzzy search ✅, mentions ✅, backlinks ✅, entity UI (sheets/search/relationships/map) ✅; pending: consistency UI, palette search, context rail, seed extension, DATA_MODEL.md, E2E |
 | 5 | **Plot & Whiteboard** | 3 | ⬜ Not started | Beat board + templates, timeline, React Flow whiteboard (200-node perf) |
 | 6 | **Export Pipeline** | 3 | ⬜ Not started | MD/HTML/EPUB/DOCX/ODT + PDF, export dialog, CI validation |
 | 7 | **Spell & Grammar** | 2 | ⬜ Not started | hunspell-WASM spellcheck, LanguageTool grammar, decorations + panel |
@@ -281,7 +281,7 @@ Each chunk is a 1–3 day work order in `CHUNK#n.md`, written so a human *or* a
 
 **Total: ~27 focused working days**, sequenced so each chunk is independently shippable and testable.
 
-**Progress:** 1 of 11 chunks complete. CHUNK #1 is built and CI-green (`pnpm typecheck`, `pnpm test`, `pnpm lint`, `pnpm build` all pass; `pnpm dev` serves the themed app shell).
+**Progress:** 1 of 11 chunks complete. CHUNK #1 is built and CI-green (`pnpm typecheck`, `pnpm test`, `pnpm lint`, `pnpm build` all pass; `pnpm dev` serves the themed app shell). CHUNK #2 and #3 are committed and CI-green. CHUNK #4 is in progress — its data layer (entity schema, fuzzy search, backlinks, consistency check, `@mention` autocomplete) and entity UI layer (character/world sheets, fuzzy search, relationship editor + map) are built and green, with a few items remaining (consistency UI wiring, palette search, context rail, seed extension, `docs/DATA_MODEL.md`, E2E).
 
 ---
 
@@ -298,4 +298,4 @@ Each chunk is a 1–3 day work order in `CHUNK#n.md`, written so a human *or* a
 
 ---
 
-*CHUNK #1 is complete. Next: read `CHUNK#2.md` and start executing. Each chunk's acceptance criteria are the gate to the next.*
+*CHUNK #1–#3 are complete and CI-green. Currently executing CHUNK #4 (Characters & World-Building). Each chunk's acceptance criteria are the gate to the next.*
diff --git a/apps/web/src/App.tsx b/apps/web/src/App.tsx
index 54b08ce..a60f616 100644
--- a/apps/web/src/App.tsx
+++ b/apps/web/src/App.tsx
@@ -13,7 +13,7 @@ import { Admin } from "./routes/Admin.js";
 
 const NAV = [
   { to: "/", label: "Write", icon: "✎", end: true },
-  { to: "/characters", label: "Characters", icon: "👤", end: false },
+  { to: "/characters", label: "Entities", icon: "👥", end: false },
   { to: "/plot", label: "Plot", icon: "🗺", end: false },
   { to: "/whiteboard", label: "Whiteboard", icon: "🧩", end: false },
   { to: "/ai", label: "AI", icon: "✨", end: false },
diff --git a/apps/web/src/components/Settings.tsx b/apps/web/src/components/Settings.tsx
index e929b7b..755bb12 100644
--- a/apps/web/src/components/Settings.tsx
+++ b/apps/web/src/components/Settings.tsx
@@ -1,4 +1,4 @@
-import { useSettings, type Density } from "../store/settings.js";
+import { useSettings, FONT_FAMILIES, type Density, type FontFamily } from "../store/settings.js";
 import { Select, Button, toast } from "@pubscript/ui";
 import { THEME_IDS, THEME_LABELS } from "@pubscript/ui";
 
@@ -46,16 +46,56 @@ export function Settings() {
             ]}
           />
         </div>
+      </div>
+
+      <div className="ps-settings-group">
+        <h3>Typography</h3>
+
+        <div className="ps-settings-row">
+          <div>
+            <div className="ps-settings-label">Font</div>
+            <div className="ps-settings-desc">Body typeface for the writing column.</div>
+          </div>
+          <Select
+            value={s.fontFamily}
+            onChange={(e) => set({ fontFamily: e.target.value as FontFamily })}
+            options={FONT_FAMILIES.map((f) => ({ value: f.value, label: f.label }))}
+          />
+        </div>
 
         <div className="ps-settings-row">
           <div>
             <div className="ps-settings-label">Font size</div>
-            <div className="ps-settings-desc">Base UI font size in pixels.</div>
+            <div className="ps-settings-desc">Body text size in the writing column.</div>
           </div>
           <Select
             value={String(s.fontSize)}
             onChange={(e) => set({ fontSize: Number(e.target.value) })}
-            options={[13, 14, 15, 16, 17, 18].map((n) => ({ value: String(n), label: `${n}px` }))}
+            options={[14, 15, 16, 17, 18, 19, 20, 21, 22].map((n) => ({ value: String(n), label: `${n}px` }))}
+          />
+        </div>
+
+        <div className="ps-settings-row">
+          <div>
+            <div className="ps-settings-label">Line spacing</div>
+            <div className="ps-settings-desc">Leading between body lines.</div>
+          </div>
+          <Select
+            value={String(s.leading)}
+            onChange={(e) => set({ leading: Number(e.target.value) })}
+            options={[1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0].map((n) => ({ value: String(n), label: n.toFixed(1) }))}
+          />
+        </div>
+
+        <div className="ps-settings-row">
+          <div>
+            <div className="ps-settings-label">Column width</div>
+            <div className="ps-settings-desc">Max width of the writing column.</div>
+          </div>
+          <Select
+            value={String(s.measure)}
+            onChange={(e) => set({ measure: Number(e.target.value) })}
+            options={[600, 660, 720, 780, 840].map((n) => ({ value: String(n), label: `${n}px` }))}
           />
         </div>
       </div>
@@ -102,6 +142,34 @@ export function Settings() {
             />
           </label>
         </div>
+
+        <div className="ps-settings-row">
+          <div>
+            <div className="ps-settings-label">Focus mode</div>
+            <div className="ps-settings-desc">Dim everything but the block under the cursor. Toggle with F2.</div>
+          </div>
+          <label style={{ display: "flex", alignItems: "center", gap: 8 }}>
+            <input
+              type="checkbox"
+              checked={s.focusMode}
+              onChange={(e) => set({ focusMode: e.target.checked })}
+            />
+          </label>
+        </div>
+
+        <div className="ps-settings-row">
+          <div>
+            <div className="ps-settings-label">Typewriter mode</div>
+            <div className="ps-settings-desc">Keep the active block centered as you type. Toggle with ⌘⇧T.</div>
+          </div>
+          <label style={{ display: "flex", alignItems: "center", gap: 8 }}>
+            <input
+              type="checkbox"
+              checked={s.typewriterMode}
+              onChange={(e) => set({ typewriterMode: e.target.checked })}
+            />
+          </label>
+        </div>
       </div>
 
       <div className="ps-settings-row">
diff --git a/apps/web/src/components/WritingView.tsx b/apps/web/src/components/WritingView.tsx
index d7dbafb..124cdeb 100644
--- a/apps/web/src/components/WritingView.tsx
+++ b/apps/web/src/components/WritingView.tsx
@@ -7,10 +7,14 @@
  *   - debounces every edit through the storage adapter via `scheduleSave`,
  *   - shows word count, scene count, and an autosave indicator.
  */
-import { useEffect } from "react";
+import { useEffect, useRef } from "react";
 import { EditorContent, usePubScriptEditor, type Editor, SCENE_BREAK } from "@pubscript/editor";
 import type { DocumentRef, AutosaveState } from "@pubscript/core";
 import { useProjectStore } from "../store/project-store.js";
+import { useSettings } from "../store/settings.js";
+
+/** Block-level tags that can contain the cursor and be highlighted in focus mode. */
+const BLOCK_TAGS = new Set(["P", "H1", "H2", "H3", "BLOCKQUOTE", "PRE", "LI", "DIV"]);
 
 /** Count words in the editor document. */
 function countWords(editor: Editor | null): number {
@@ -53,6 +57,12 @@ export function WritingView({ onChapterChange }: WritingViewProps) {
   const flushAutosave = useProjectStore((s) => s.flushAutosave);
   const autosave = useProjectStore((s) => s.autosave);
 
+  const focusMode = useSettings((st) => st.focusMode);
+  const typewriterMode = useSettings((st) => st.typewriterMode);
+  const setSettings = useSettings((st) => st.set);
+
+  const editorDomRef = useRef<HTMLDivElement | null>(null);
+
   const chapter = chapters.find((c) => c.id === activeChapterId) ?? null;
   const projectId = project?.id ?? null;
 
@@ -83,6 +93,75 @@ export function WritingView({ onChapterChange }: WritingViewProps) {
     editor.commands.focus();
   }, [editor, chapter?.id]);
 
+  // Focus mode: dim every block except the one holding the cursor. Typewriter
+  // mode: keep the active block vertically centered as the user types.
+  useEffect(() => {
+    if (!editor) return;
+    const editorDom = editorDomRef.current;
+    if (!editorDom) return;
+
+    const activeBlock = (): HTMLElement | null => {
+      const $from = editor.state.selection.$from;
+      const dom = editor.view.nodeDOM($from.pos) as HTMLElement | null;
+      let el: HTMLElement | null = dom;
+      while (el && editorDom.contains(el)) {
+        if (BLOCK_TAGS.has(el.tagName)) return el;
+        el = el.parentElement;
+      }
+      return null;
+    };
+
+    if (focusMode) {
+      const apply = () => {
+        const block = activeBlock();
+        const blocks = editorDom.querySelectorAll<HTMLElement>("p, h1, h2, h3, blockquote, pre, li, div");
+        blocks.forEach((b) => b.classList.toggle("ps-focus-active", b === block));
+      };
+      editor.on("selectionUpdate", apply);
+      editor.on("update", apply);
+      apply();
+      return () => {
+        editor.off("selectionUpdate", apply);
+        editor.off("update", apply);
+      };
+    }
+
+    if (typewriterMode) {
+      const scroll = () => {
+        const block = activeBlock();
+        block?.scrollIntoView({ block: "center" });
+      };
+      editor.on("selectionUpdate", scroll);
+      editor.on("update", scroll);
+      scroll();
+      return () => {
+        editor.off("selectionUpdate", scroll);
+        editor.off("update", scroll);
+      };
+    }
+
+    return undefined;
+  }, [editor, focusMode, typewriterMode]);
+
+  // Keyboard shortcuts: F2 toggles focus mode, Ctrl/Cmd+Shift+T toggles
+  // typewriter mode. Only active while editing inside the writing surface.
+  useEffect(() => {
+    const dom = editorDomRef.current;
+    if (!dom) return;
+    const onKey = (e: KeyboardEvent) => {
+      const isMod = e.metaKey || e.ctrlKey;
+      if (e.key === "F2") {
+        e.preventDefault();
+        setSettings({ focusMode: !focusMode });
+      } else if (isMod && (e.key === "t" || e.key === "T") && e.shiftKey) {
+        e.preventDefault();
+        setSettings({ typewriterMode: !typewriterMode });
+      }
+    };
+    dom.addEventListener("keydown", onKey);
+    return () => dom.removeEventListener("keydown", onKey);
+  }, [editorDomRef, focusMode, typewriterMode, setSettings]);
+
   // Flush pending edits when the user closes or navigates away.
   useEffect(() => {
     const onBeforeUnload = () => flushAutosave();
@@ -120,14 +199,36 @@ export function WritingView({ onChapterChange }: WritingViewProps) {
             ))}
           </select>
         </label>
+
+        <div className="ps-toolbar-group">
+          <button
+            type="button"
+            className={`ps-tool${focusMode ? " is-active" : ""}`}
+            title="Focus mode (F2)"
+            aria-pressed={focusMode}
+            onClick={() => setSettings({ focusMode: !focusMode })}
+          >
+            Focus
+          </button>
+          <button
+            type="button"
+            className={`ps-tool${typewriterMode ? " is-active" : ""}`}
+            title="Typewriter mode (⌘⇧T)"
+            aria-pressed={typewriterMode}
+            onClick={() => setSettings({ typewriterMode: !typewriterMode })}
+          >
+            Typewriter
+          </button>
+        </div>
+
         <div className="ps-autosave-indicator" data-status={autosave.saving ? "saving" : autosave.dirty ? "dirty" : "saved"}>
           <span className="ps-autosave-dot" />
           <span>{autosaveLabel(autosave)}</span>
         </div>
       </div>
 
-      <div className="ps-content ps-editor-writing">
-        <div className="ps-editor">
+      <div className={`ps-content ps-editor-writing${focusMode ? " ps-editor-focus" : ""}`}>
+        <div className="ps-editor" ref={editorDomRef}>
           <EditorContent editor={editor} />
         </div>
       </div>
diff --git a/apps/web/src/features/entities/EntitiesView.tsx b/apps/web/src/features/entities/EntitiesView.tsx
new file mode 100644
index 0000000..b8fff4c
--- /dev/null
+++ b/apps/web/src/features/entities/EntitiesView.tsx
@@ -0,0 +1,186 @@
+/**
+ * EntitiesView — the entity engine directory (Chunk #4).
+ *
+ * A tabbed, fuzzy-searchable directory of people, places, and notes. Each card
+ * opens the create/edit drawer. A "New" control creates an entity of a chosen
+ * kind. Characters show a relationship map in the drawer.
+ */
+import React from "react";
+import type { Entity } from "@pubscript/core";
+import { fuzzySort } from "@pubscript/core";
+import { Button, Input, Select } from "@pubscript/ui";
+import { useProjectStore } from "../../store/project-store.js";
+import { EntityEditor } from "./EntityEditor.js";
+import { entityLabel } from "./RelationshipEditor.js";
+
+type TabId = "all" | "people" | "places" | "notes";
+
+interface Tab {
+  id: TabId;
+  label: string;
+  /** Filter predicate over entities, or null for "all". */
+  match: (e: Entity) => boolean;
+}
+
+const TABS: Tab[] = [
+  { id: "all", label: "All", match: () => true },
+  { id: "people", label: "People", match: (e) => "relationships" in e },
+  { id: "places", label: "Places", match: (e) => "fields" in e },
+  { id: "notes", label: "Notes", match: (e) => "body" in e },
+];
+
+const KIND_OPTIONS = [
+  { value: "character", label: "Character" },
+  { value: "world", label: "Place" },
+  { value: "note", label: "Note" },
+];
+
+/** Human-readable text used for fuzzy matching. */
+function searchText(e: Entity): string {
+  if ("fields" in e) {
+    return [e.name, e.kind, ...Object.values(e.fields).filter((v) => typeof v === "string")].join(" ");
+  }
+  if ("body" in e) {
+    return [e.body, ...e.tags].join(" ");
+  }
+  const c = e;
+  const rel = (c.relationships ?? []).map((r) => r.kind).join(" ");
+  return [c.name, c.role, c.bio, c.appearance, c.voice, c.arc, c.status, rel, ...c.tags].join(" ");
+}
+
+export function EntitiesView() {
+  const entities = useProjectStore((s) => s.entities);
+  const createEntity = useProjectStore((s) => s.createEntity);
+  const updateEntity = useProjectStore((s) => s.updateEntity);
+  const deleteEntity = useProjectStore((s) => s.deleteEntity);
+
+  const [tab, setTab] = React.useState<TabId>("all");
+  const [query, setQuery] = React.useState("");
+  const [newKind, setNewKind] = React.useState("character");
+  const [draft, setDraft] = React.useState<Entity | null>(null);
+  const [open, setOpen] = React.useState(false);
+
+  const visible = React.useMemo(() => {
+    const filtered = entities.filter((e) => TABS.find((t) => t.id === tab)!.match(e));
+    return query ? fuzzySort(filtered, query, searchText) : filtered;
+  }, [entities, tab, query]);
+
+  const openNew = async () => {
+    const e = await createEntity(newKind);
+    setDraft(e);
+    setOpen(true);
+  };
+
+  const openEntity = (e: Entity) => {
+    setDraft(e);
+    setOpen(true);
+  };
+
+  const save = (e: Entity) => {
+    void updateEntity(e);
+  };
+
+  const remove = async (id: string) => {
+    await deleteEntity(id);
+    setOpen(false);
+    setDraft(null);
+  };
+
+  return (
+    <div className="ps-entities-view">
+      <div className="ps-entity-toolbar">
+        <div className="ps-entity-tabs">
+          {TABS.map((t) => (
+            <button
+              key={t.id}
+              type="button"
+              className={"ps-entity-tab" + (t.id === tab ? " active" : "")}
+              onClick={() => setTab(t.id)}
+            >
+              {t.label}
+            </button>
+          ))}
+        </div>
+        <div className="ps-entity-new-group">
+          <Select
+            className="ps-entity-new-kind"
+            value={newKind}
+            options={KIND_OPTIONS}
+            onChange={(ev) => setNewKind(ev.target.value)}
+          />
+          <Button onClick={openNew}>+ New</Button>
+        </div>
+      </div>
+
+      <div className="ps-entity-search">
+        <Input
+          className="ps-entity-search-input"
+          placeholder="Search entities…"
+          value={query}
+          onChange={(ev) => setQuery(ev.target.value)}
+        />
+      </div>
+
+      {visible.length === 0 ? (
+        <p className="ps-muted">No entities match.</p>
+      ) : (
+        <div className="ps-entity-grid">
+          {visible.map((e) => (
+            <button
+              key={e.id}
+              type="button"
+              className="ps-entity-card"
+              onClick={() => openEntity(e)}
+            >
+              <div className="ps-entity-card-top">
+                <span className="ps-entity-type-badge">{badgeFor(e)}</span>
+              </div>
+              <div className="ps-entity-card-name">{entityLabel(e)}</div>
+              <div className="ps-entity-card-sub">{subFor(e)}</div>
+              {tagsFor(e).length > 0 && (
+                <div className="ps-entity-card-tags">
+                  {tagsFor(e).slice(0, 4).map((t) => (
+                    <span key={t} className="ps-entity-tag">
+                      {t}
+                    </span>
+                  ))}
+                </div>
+              )}
+            </button>
+          ))}
+        </div>
+      )}
+
+      <EntityEditor
+        entity={draft}
+        entities={entities}
+        open={open}
+        onClose={() => setOpen(false)}
+        onSave={save}
+        onDelete={remove}
+      />
+    </div>
+  );
+}
+
+/** Short badge label for a card. */
+function badgeFor(e: Entity): string {
+  if ("fields" in e) return e.kind;
+  if ("body" in e) return "note";
+  return "person";
+}
+
+/** Secondary line shown under the name. */
+function subFor(e: Entity): string {
+  if ("fields" in e) return e.kind;
+  if ("body" in e) return e.body.slice(0, 80) || "Note";
+  const c = e;
+  return c.role || c.status || "";
+}
+
+/** Tags for a card. */
+function tagsFor(e: Entity): string[] {
+  if ("fields" in e) return [];
+  if ("body" in e) return e.tags;
+  return e.tags;
+}
diff --git a/apps/web/src/features/entities/EntityEditor.tsx b/apps/web/src/features/entities/EntityEditor.tsx
new file mode 100644
index 0000000..26544aa
--- /dev/null
+++ b/apps/web/src/features/entities/EntityEditor.tsx
@@ -0,0 +1,109 @@
+/**
+ * EntityEditor — the right-rail drawer for creating and editing an entity.
+ *
+ * Composes the generic `EntityFields` renderer plus, for characters, the
+ * `RelationshipEditor`. Emits the full entity on Save and deletes on demand.
+ */
+import React from "react";
+import type { Character, Entity } from "@pubscript/core";
+import { Button } from "@pubscript/ui";
+import { EntityFields } from "./EntityFields.js";
+import { RelationshipEditor } from "./RelationshipEditor.js";
+import { RelationshipMap } from "./RelationshipMap.js";
+
+interface EntityEditorProps {
+  entity: Entity | null;
+  entities: Entity[];
+  open: boolean;
+  onClose: () => void;
+  onSave: (entity: Entity) => void;
+  onDelete: (id: string) => void;
+}
+
+function isCharacter(e: Entity): e is Character {
+  return "relationships" in e;
+}
+
+export function EntityEditor({
+  entity,
+  entities,
+  open,
+  onClose,
+  onSave,
+  onDelete,
+}: EntityEditorProps) {
+  const [draft, setDraft] = React.useState<Entity | null>(entity);
+
+  React.useEffect(() => {
+    setDraft(entity);
+  }, [entity]);
+
+  if (!open || !draft) return null;
+
+  const isExisting = entities.some((e) => e.id === draft.id);
+  const isCharacterDraft = isCharacter(draft);
+  const canDelete = isExisting && isCharacterDraft;
+
+  const title = isCharacterDraft
+    ? (draft.name || "Edit character")
+    : "fields" in draft
+      ? `Edit ${draft.kind}`
+      : "Edit note";
+
+  const patch = (p: Partial<Entity>) => {
+    setDraft({ ...draft, ...p });
+  };
+
+  const save = () => {
+    onSave(draft);
+    onClose();
+  };
+
+  return (
+    <aside className="ps-entity-editor">
+      <header className="ps-entity-editor-header">
+        <h2>{isExisting ? title : "New entity"}</h2>
+        <button type="button" className="ps-icon-btn" aria-label="Close" onClick={onClose}>
+          ×
+        </button>
+      </header>
+
+      <div className="ps-entity-editor-body">
+        {isCharacterDraft ? (
+          <>
+            <EntityFields entity={draft} onChange={patch} />
+            <div className="ps-relationship-section">
+              <h3>Relationships</h3>
+              <RelationshipEditor
+                character={draft}
+                entities={entities}
+                onChange={(relationships) => patch({ relationships })}
+              />
+              <div className="ps-relationship-map-wrap">
+                <RelationshipMap entities={entities} focusId={draft.id} />
+              </div>
+            </div>
+          </>
+        ) : (
+          <EntityFields entity={draft} onChange={patch} />
+        )}
+      </div>
+
+      <footer className="ps-entity-editor-actions">
+        <div className="ps-spacer" />
+        {canDelete ? (
+          <Button
+            variant="danger"
+            onClick={() => onDelete(draft.id)}
+          >
+            Delete
+          </Button>
+        ) : null}
+        <Button variant="ghost" onClick={onClose}>
+          Cancel
+        </Button>
+        <Button onClick={save}>Save</Button>
+      </footer>
+    </aside>
+  );
+}
diff --git a/apps/web/src/features/entities/EntityFields.tsx b/apps/web/src/features/entities/EntityFields.tsx
new file mode 100644
index 0000000..a9646d4
--- /dev/null
+++ b/apps/web/src/features/entities/EntityFields.tsx
@@ -0,0 +1,165 @@
+/**
+ * EntityFields — generic field renderer for the entity editor.
+ *
+ * Renders the fields defined in the core `ENTITY_FIELDS` registry for the
+ * entity's kind. Field values live at the top level for characters/notes and
+ * inside the `fields` record for world items; `getFieldValue`/`setFieldValue`
+ * abstract that away so the renderer is kind-agnostic.
+ */
+import React from "react";
+import type { Entity, FieldDef } from "@pubscript/core";
+import { ENTITY_FIELDS } from "@pubscript/core";
+import { Input } from "@pubscript/ui";
+import { Select } from "@pubscript/ui";
+
+/** Read a field value from an entity, regardless of where it is stored. */
+export function getFieldValue(e: Entity, key: string): string | string[] {
+  if ("fields" in e) {
+    const v = e.fields[key];
+    return typeof v === "string" ? v : "";
+  }
+  const v = (e as unknown as Record<string, unknown>)[key];
+  if (Array.isArray(v)) return v;
+  return typeof v === "string" ? v : "";
+}
+
+/** Return a copy of `e` with `key` set to `value`. */
+export function setFieldValue(e: Entity, key: string, value: string | string[]): Entity {
+  if ("fields" in e) {
+    return { ...e, fields: { ...e.fields, [key]: value } };
+  }
+  return { ...e, [key]: value };
+}
+
+/** The field definitions for an entity's kind. */
+export function fieldsFor(e: Entity): FieldDef[] {
+  const kind = "fields" in e ? e.kind : "body" in e ? "note" : "character";
+  return ENTITY_FIELDS[kind]?.fields ?? [];
+}
+
+interface EntityFieldsProps {
+  entity: Entity;
+  onChange: (patch: Partial<Entity>) => void;
+}
+
+function renderField(
+  field: FieldDef,
+  value: string | string[],
+  onChange: (v: string | string[]) => void,
+) {
+  const label = (
+    <label className="ps-field-label">
+      {field.label}
+      {field.hint ? <span className="ps-field-hint">{field.hint}</span> : null}
+    </label>
+  );
+
+  switch (field.type) {
+    case "textarea":
+      return (
+        <div className="ps-field-span-2">
+          {label}
+          <textarea
+            className="ps-textarea ps-input"
+            value={typeof value === "string" ? value : ""}
+            onChange={(ev) => onChange(ev.target.value)}
+          />
+        </div>
+      );
+    case "select":
+      return (
+        <div>
+          {label}
+          <Select
+            value={typeof value === "string" ? value : ""}
+            options={(field.options ?? []).map((o) => ({ value: o, label: o }))}
+            onChange={(ev) => onChange(ev.target.value)}
+          />
+        </div>
+      );
+    case "list":
+      return <TagField value={Array.isArray(value) ? value : []} onChange={onChange} />;
+    case "link":
+    case "text":
+    default:
+      return (
+        <div className="ps-field-span-2">
+          {label}
+          <Input
+            className="ps-input"
+            value={typeof value === "string" ? value : ""}
+            onChange={(ev) => onChange(ev.target.value)}
+          />
+        </div>
+      );
+  }
+}
+
+/** A small inline tag editor (add on Enter, remove on ×). */
+function TagField({
+  value,
+  onChange,
+}: {
+  value: string[];
+  onChange: (v: string[]) => void;
+}) {
+  const [draft, setDraft] = React.useState("");
+
+  const add = () => {
+    const t = draft.trim();
+    if (t && !value.includes(t)) {
+      onChange([...value, t]);
+    }
+    setDraft("");
+  };
+
+  return (
+    <div className="ps-tag-field">
+      <div className="ps-tag-list">
+        {value.map((t, i) => (
+          <span key={`${t}-${i}`} className="ps-tag-chip">
+            {t}
+            <button
+              type="button"
+              className="ps-tag-remove"
+              aria-label={`Remove ${t}`}
+              onClick={() => onChange(value.filter((_, idx) => idx !== i))}
+            >
+              ×
+            </button>
+          </span>
+        ))}
+      </div>
+      <input
+        className="ps-input"
+        value={draft}
+        placeholder="Add tag + Enter"
+        onChange={(ev) => setDraft(ev.target.value)}
+        onKeyDown={(ev) => {
+          if (ev.key === "Enter") {
+            ev.preventDefault();
+            add();
+          }
+        }}
+      />
+    </div>
+  );
+}
+
+export function EntityFields({ entity, onChange }: EntityFieldsProps) {
+  const fields = fieldsFor(entity);
+
+  return (
+    <div className="ps-entity-fields">
+      {fields.map((field) => (
+        <div key={field.key} className="ps-field">
+          {renderField(
+            field,
+            getFieldValue(entity, field.key),
+            (v) => onChange({ [field.key]: v } as Partial<Entity>),
+          )}
+        </div>
+      ))}
+    </div>
+  );
+}
diff --git a/apps/web/src/features/entities/RelationshipEditor.tsx b/apps/web/src/features/entities/RelationshipEditor.tsx
new file mode 100644
index 0000000..d867a3e
--- /dev/null
+++ b/apps/web/src/features/entities/RelationshipEditor.tsx
@@ -0,0 +1,135 @@
+/**
+ * RelationshipEditor — editor for a character's relationships.
+ *
+ * Renders the current relationships (with the target entity's name), lets the
+ * user add a new relationship (pick a target entity + kind + note), and remove
+ * one. Emits the new relationships array via `onChange`.
+ */
+import type { Character, Entity, RelationshipKind } from "@pubscript/core";
+import { Input } from "@pubscript/ui";
+import { Select } from "@pubscript/ui";
+
+/** All relationship kinds, in display order. */
+export const RELATIONSHIP_KINDS: RelationshipKind[] = [
+  "ally",
+  "rival",
+  "family",
+  "sibling",
+  "friend",
+  "spouse",
+  "partner",
+  "mentor",
+  "romantic",
+  "custom",
+];
+
+const KIND_LABEL: Record<RelationshipKind, string> = {
+  ally: "Ally",
+  rival: "Rival",
+  family: "Family",
+  sibling: "Sibling",
+  friend: "Friend",
+  spouse: "Spouse",
+  partner: "Partner",
+  mentor: "Mentor",
+  romantic: "Romantic",
+  custom: "Custom",
+};
+
+interface RelationshipEditorProps {
+  character: Character;
+  /** All entities available as relationship targets. */
+  entities: Entity[];
+  onChange: (relationships: Character["relationships"]) => void;
+}
+
+export function RelationshipEditor({
+  character,
+  entities,
+  onChange,
+}: RelationshipEditorProps) {
+  const targets = entities.filter((e) => e.id !== character.id);
+
+  const targetName = (id: string) => {
+    const e = entities.find((e) => e.id === id);
+    return e ? entityLabel(e) : "(unknown)";
+  };
+
+  const remove = (targetId: string) => {
+    onChange(character.relationships.filter((r) => r.targetId !== targetId));
+  };
+
+  return (
+    <div className="ps-relationship-editor">
+      <div className="ps-relationship-list">
+        {character.relationships.length === 0 && (
+          <p className="ps-relationship-empty">
+            No relationships yet. Add one below to start mapping this character's
+            connections.
+          </p>
+        )}
+        {character.relationships.map((r, i) => (
+          <div key={`${r.targetId}-${i}`} className="ps-relationship-item">
+            <span className="ps-relationship-kind">{KIND_LABEL[r.kind] ?? r.kind}</span>
+            <span className="ps-relationship-target">{targetName(r.targetId)}</span>
+            {r.note ? <span className="ps-relationship-note">{r.note}</span> : null}
+            <button
+              type="button"
+              className="ps-relationship-remove"
+              aria-label="Remove relationship"
+              onClick={() => remove(r.targetId)}
+            >
+              ×
+            </button>
+          </div>
+        ))}
+      </div>
+
+      <div className="ps-relationship-add">
+        <Select
+          className="ps-relationship-target-select"
+          value=""
+          options={[
+            { value: "", label: "Target…" },
+            ...targets.map((e) => ({ value: e.id, label: entityLabel(e) })),
+          ]}
+          onChange={(ev) => {
+            const targetId = ev.target.value;
+            onChange([...character.relationships, { targetId, kind: "ally", note: "" }]);
+          }}
+        />
+        <Select
+          className="ps-relationship-kind-select"
+          value="ally"
+          options={RELATIONSHIP_KINDS.map((k) => ({ value: k, label: KIND_LABEL[k] }))}
+          onChange={(ev) => {
+            const kind = ev.target.value as RelationshipKind;
+            const next = character.relationships.slice();
+            const last = next[next.length - 1];
+            if (last) last.kind = kind;
+            onChange(next);
+          }}
+        />
+        <Input
+          className="ps-relationship-note"
+          placeholder="Note (optional)"
+          value={character.relationships[character.relationships.length - 1]?.note ?? ""}
+          onChange={(ev) => {
+            const note = ev.target.value;
+            const next = character.relationships.slice();
+            const last = next[next.length - 1];
+            if (last) last.note = note;
+            onChange(next);
+          }}
+        />
+      </div>
+    </div>
+  );
+}
+
+/** Human label for an entity used as a relationship target. */
+export function entityLabel(e: Entity): string {
+  if ("fields" in e) return `${e.name} (${e.kind})`;
+  if ("body" in e) return e.body.slice(0, 40) || "Note";
+  return e.name;
+}
diff --git a/apps/web/src/features/entities/RelationshipMap.tsx b/apps/web/src/features/entities/RelationshipMap.tsx
new file mode 100644
index 0000000..f930db8
--- /dev/null
+++ b/apps/web/src/features/entities/RelationshipMap.tsx
@@ -0,0 +1,167 @@
+/**
+ * RelationshipMap — a lightweight force-directed SVG graph of a character's
+ * relationships.
+ *
+ * Pure SVG, no external graphing dependency. A small simulation runs once when
+ * the node set changes to compute stable positions; edges are drawn as lines
+ * and nodes as labelled circles. Non-character entities are ignored.
+ */
+import type { Character, Entity } from "@pubscript/core";
+
+interface Node {
+  id: string;
+  label: string;
+  color: string;
+  x: number;
+  y: number;
+  vx: number;
+  vy: number;
+}
+
+const WIDTH = 520;
+const HEIGHT = 320;
+const CENTER = { x: WIDTH / 2, y: HEIGHT / 2 };
+
+/** Extract the characters from a list of entities. */
+function characters(entities: Entity[]): Character[] {
+  return entities.filter((e): e is Character => "relationships" in e && e.name.length > 0);
+}
+
+/** Human label for a node in the graph. */
+function nodeLabel(e: Entity): string {
+  if ("fields" in e) return e.name;
+  if ("body" in e) return e.body.slice(0, 12) || "Note";
+  return e.name;
+}
+
+/** Run a simple force simulation for a fixed number of steps to lay out nodes. */
+function layout(nodes: Node[], iterations = 240): Node[] {
+  const REPULSION = 2600;
+  const CENTER_FORCE = 0.004;
+  const DAMPING = 0.85;
+  const PAD = 40;
+
+  for (let iter = 0; iter < iterations; iter++) {
+    for (const a of nodes) {
+      a.vx = 0;
+      a.vy = 0;
+    }
+    // Pairwise repulsion.
+    for (let i = 0; i < nodes.length; i++) {
+      for (let j = i + 1; j < nodes.length; j++) {
+        const a = nodes[i]!;
+        const b = nodes[j]!;
+        let dx = a.x - b.x;
+        let dy = a.y - b.y;
+        let dist2 = dx * dx + dy * dy;
+        if (dist2 < 1) {
+          dx = (Math.random() - 0.5) * 2;
+          dy = (Math.random() - 0.5) * 2;
+          dist2 = dx * dx + dy * dy || 1;
+        }
+        const force = REPULSION / dist2;
+        const dist = Math.sqrt(dist2);
+        const fx = (dx / dist) * force;
+        const fy = (dy / dist) * force;
+        a.vx += fx;
+        a.vy += fy;
+        b.vx -= fx;
+        b.vy -= fy;
+      }
+    }
+    // Center gravity.
+    for (const n of nodes) {
+      n.vx += (CENTER.x - n.x) * CENTER_FORCE;
+      n.vy += (CENTER.y - n.y) * CENTER_FORCE;
+    }
+    // Integrate + clamp to padding.
+    for (const n of nodes) {
+      n.vx *= DAMPING;
+      n.vy *= DAMPING;
+      n.x += n.vx;
+      n.y += n.vy;
+      n.x = Math.max(PAD, Math.min(WIDTH - PAD, n.x));
+      n.y = Math.max(PAD, Math.min(HEIGHT - PAD, n.y));
+    }
+  }
+  return nodes;
+}
+
+const CHARACTER_COLOR = "#8b5cf6";
+const RELATED_COLOR = "#38bdf8";
+
+interface RelationshipMapProps {
+  entities: Entity[];
+  /** The character whose relationships are centered in the graph. */
+  focusId?: string;
+}
+
+export function RelationshipMap({ entities, focusId }: RelationshipMapProps) {
+  const chars = characters(entities);
+
+  // Build the node/edge set. Start from the focus character (or the first
+  // character) and include everyone it is directly related to.
+  const focus = focusId ? chars.find((c) => c.id === focusId) : chars[0];
+  const focusChars = focus ? [focus] : chars;
+
+  const nodeIds = new Set<string>();
+  const edges: Array<[string, string]> = [];
+  for (const c of focusChars) {
+    nodeIds.add(c.id);
+    for (const r of c.relationships) {
+      nodeIds.add(r.targetId);
+      edges.push([c.id, r.targetId]);
+    }
+  }
+
+  // Seed positions on a circle, then simulate.
+  const seeded: Node[] = [...nodeIds].map((id, i) => {
+    const angle = (2 * Math.PI * i) / Math.max(1, nodeIds.size);
+    const label = nodeLabel(entities.find((e) => e.id === id)!) || id.slice(0, 6);
+    return {
+      id,
+      label,
+      color: id === focus?.id ? CHARACTER_COLOR : RELATED_COLOR,
+      x: CENTER.x + Math.cos(angle) * 110,
+      y: CENTER.y + Math.sin(angle) * 70,
+      vx: 0,
+      vy: 0,
+    };
+  });
+
+  const laidOut = layout(seeded);
+  const pos = new Map(laidOut.map((n) => [n.id, n]));
+
+  if (laidOut.length === 0) {
+    return (
+      <div className="ps-relationship-map-empty">
+        {focusChars.length === 0
+          ? "No characters yet."
+          : "Select a character to map its relationships."}
+      </div>
+    );
+  }
+
+  return (
+    <svg viewBox={`0 0 ${WIDTH} ${HEIGHT}`} className="ps-relationship-svg" role="img" aria-label="Relationship map">
+      <g>
+        {edges.map(([from, to], i) => {
+          const a = pos.get(from);
+          const b = pos.get(to);
+          if (!a || !b) return null;
+          return <line key={`e-${i}`} x1={a.x} y1={a.y} x2={b.x} y2={b.y} className="ps-rel-edge" />;
+        })}
+      </g>
+      <g>
+        {laidOut.map((n) => (
+          <g key={n.id}>
+            <circle cx={n.x} cy={n.y} r={14} fill={n.color} className="ps-rel-node" />
+            <text x={n.x} y={n.y + 3} textAnchor="middle" className="ps-rel-node-label">
+              {n.label.length > 8 ? n.label.slice(0, 7) + "…" : n.label}
+            </text>
+          </g>
+        ))}
+      </g>
+    </svg>
+  );
+}
diff --git a/apps/web/src/features/entities/index.ts b/apps/web/src/features/entities/index.ts
new file mode 100644
index 0000000..4dcbd63
--- /dev/null
+++ b/apps/web/src/features/entities/index.ts
@@ -0,0 +1,12 @@
+/**
+ * Entities feature barrel — Chunk #4 entity engine UI.
+ *
+ * Exposes the app-facing `EntitiesView` (the `/entities` route) and the
+ * composable pieces it's built from, so other routes (e.g. the editor mention
+ * integration) can reuse the editor and picker without importing internals.
+ */
+export { EntitiesView } from "./EntitiesView.js";
+export { EntityEditor } from "./EntityEditor.js";
+export { EntityFields } from "./EntityFields.js";
+export { RelationshipEditor } from "./RelationshipEditor.js";
+export { RelationshipMap } from "./RelationshipMap.js";
diff --git a/apps/web/src/main.tsx b/apps/web/src/main.tsx
index 70e1869..50cc417 100644
--- a/apps/web/src/main.tsx
+++ b/apps/web/src/main.tsx
@@ -4,6 +4,7 @@ import { BrowserRouter } from "react-router-dom";
 import App from "./App.js";
 import "@pubscript/editor/styles";
 import "./styles/writing.css";
+import "./styles/entities.css";
 
 createRoot(document.getElementById("root")!).render(
   <StrictMode>
diff --git a/apps/web/src/routes/Characters.tsx b/apps/web/src/routes/Characters.tsx
index 90c153a..8a7d08e 100644
--- a/apps/web/src/routes/Characters.tsx
+++ b/apps/web/src/routes/Characters.tsx
@@ -1,52 +1,14 @@
-import { Tabs, Badge, Button, EmptyState } from "@pubscript/ui";
-
-const CHARACTERS = [
-  { id: "c1", name: "Mara Vell", role: "Protagonist", kind: "Human" },
-  { id: "c2", name: "Old Corvin", role: "Mentor", kind: "Human" },
-  { id: "c3", name: "The Cartographer", role: "Antagonist", kind: "Unknown" },
-];
+import { EntitiesView } from "../features/entities/index.js";
 
+/**
+ * Entities route — Chunk #4 entity engine.
+ *
+ * Replaces the placeholder character list with the full entity engine: a
+ * tabbed, fuzzy-searchable directory of people, places, and things, plus a
+ * relationship map and the create/edit/delete drawer.
+ */
 export function Characters() {
-  return (
-    <div className="ps-content">
-      <div style={{ display: "flex", alignItems: "center", justifyContent: "space-between", marginBottom: 16 }}>
-        <h1 style={{ margin: 0, fontSize: 24 }}>Characters</h1>
-        <Button variant="primary">+ New character</Button>
-      </div>
-
-      <Tabs
-        defaultActive="characters"
-        tabs={[
-          {
-            id: "characters",
-            label: "All",
-            badge: CHARACTERS.length,
-            content: (
-              <div style={{ display: "grid", gap: 10 }}>
-                {CHARACTERS.map((c) => (
-                  <div key={c.id} className="ps-settings-row" style={{ cursor: "pointer" }}>
-                    <div>
-                      <div style={{ fontWeight: 600 }}>{c.name}</div>
-                      <div className="ps-settings-desc">{c.role}</div>
-                    </div>
-                    <Badge variant="accent">{c.kind}</Badge>
-                  </div>
-                ))}
-              </div>
-            ),
-          },
-          {
-            id: "locations",
-            label: "Locations",
-            content: <EmptyState icon="📍" title="Locations" description="Locations appear here once added to a chapter." />,
-          },
-          {
-            id: "factions",
-            label: "Factions",
-            content: <EmptyState icon="🏳️" title="No factions yet" description="Group characters into factions to track loyalties." />,
-          },
-        ]}
-      />
-    </div>
-  );
+  return <EntitiesView />;
 }
+
+export default Characters;
diff --git a/apps/web/src/store/project-store.ts b/apps/web/src/store/project-store.ts
index d8a919c..408414b 100644
--- a/apps/web/src/store/project-store.ts
+++ b/apps/web/src/store/project-store.ts
@@ -14,10 +14,12 @@ import {
   type AutosaveState,
   type Chapter,
   type DocumentRef,
+  type Entity,
   type ProjectMeta,
   type StorageAdapter,
 } from "@pubscript/core";
 import { storageLocal } from "@pubscript/core/local";
+import { createUlid } from "@pubscript/core";
 import { create } from "zustand";
 import { seedDemoProject } from "./seed.js";
 
@@ -31,6 +33,10 @@ interface ProjectStore {
   error: string | null;
   autosave: AutosaveState;
 
+  // --- entities (Chunk #4) ---
+  entities: Entity[];
+  entitiesLoaded: boolean;
+
   // --- actions ---
   /** Load the project (seed a demo if empty) and select the first chapter. */
   init: () => Promise<void>;
@@ -40,9 +46,44 @@ interface ProjectStore {
   scheduleSave: (ref: DocumentRef) => void;
   /** Flush any pending save immediately (beforeunload / chapter switch). */
   flushAutosave: () => void;
+
+  // --- entity actions ---
+  /** Load all entities for the active project, optionally filtered by kind. */
+  loadEntities: (kind?: string) => Promise<void>;
+  /** Create a new entity of the given kind ("character" | "world" | "note"). */
+  createEntity: (kind: string) => Promise<Entity>;
+  /** Persist an updated entity. */
+  updateEntity: (entity: Entity) => Promise<void>;
+  /** Delete an entity by id. */
+  deleteEntity: (id: string) => Promise<void>;
 }
 
-export const useProjectStore = create<ProjectStore>((set) => {
+/** Build a blank entity of the given kind for the active project. */
+function emptyEntity(kind: string, projectId: string): Entity {
+  const id = createUlid();
+  if (kind === "character") {
+    return {
+      id,
+      projectId,
+      name: "",
+      role: "",
+      bio: "",
+      appearance: "",
+      voice: "",
+      relationships: [],
+      arc: "",
+      status: "active",
+      tags: [],
+    };
+  }
+  if (kind === "note") {
+    return { id, projectId, body: "", pinned: false, tags: [] };
+  }
+  // world
+  return { id, projectId, kind: "location", name: "", fields: {} };
+}
+
+export const useProjectStore = create<ProjectStore>((set, get) => {
   let autosave: ReturnType<typeof createAutosave> | null = null;
 
   return {
@@ -53,6 +94,8 @@ export const useProjectStore = create<ProjectStore>((set) => {
     status: "idle",
     error: null,
     autosave: { dirty: false, saving: false, lastSavedAt: null, status: "saved" },
+    entities: [],
+    entitiesLoaded: false,
 
     init: async () => {
       set({ status: "loading", error: null });
@@ -76,6 +119,9 @@ export const useProjectStore = create<ProjectStore>((set) => {
 
         const activeChapterId = chapters.length > 0 ? chapters[0]!.id : null;
         set({ adapter, project, chapters, activeChapterId, status: "ready" });
+
+        // Load entities for the entity engine.
+        await get().loadEntities();
       } catch (e) {
         set({ error: e instanceof Error ? e.message : String(e), status: "ready" });
       }
@@ -100,5 +146,43 @@ export const useProjectStore = create<ProjectStore>((set) => {
         void autosave.flush();
       }
     },
+
+    loadEntities: async (kind) => {
+      const { adapter, project } = get();
+      if (!adapter || !project) return;
+      const entities = await adapter.listEntities(project.id, kind);
+      set({ entities, entitiesLoaded: true });
+    },
+
+    createEntity: async (kind) => {
+      const { adapter, project } = get();
+      if (!adapter || !project) throw new Error("No active project.");
+      const entity = emptyEntity(kind, project.id);
+      await adapter.saveEntity(entity);
+      set((state) => ({ entities: [...state.entities, entity] }));
+      return entity;
+    },
+
+    updateEntity: async (entity) => {
+      const { adapter } = get();
+      if (!adapter) throw new Error("No storage adapter.");
+      await adapter.saveEntity(entity);
+      set((state) => ({
+        entities: state.entities.map((e) => (e.id === entity.id ? entity : e)),
+      }));
+    },
+
+    deleteEntity: async (id) => {
+      const { adapter, project } = get();
+      if (!adapter || !project) throw new Error("No active project.");
+      const entity = get().entities.find((e) => e.id === id);
+      if (entity) {
+        const kind = "fields" in entity ? "world" : "body" in entity ? "note" : "character";
+        await adapter.deleteEntity(project.id, kind, id);
+      }
+      set((state) => ({
+        entities: state.entities.filter((e) => e.id !== id),
+      }));
+    },
   };
 });
diff --git a/apps/web/src/store/settings.ts b/apps/web/src/store/settings.ts
index 51c9c1b..ed5b27a 100644
--- a/apps/web/src/store/settings.ts
+++ b/apps/web/src/store/settings.ts
@@ -3,24 +3,49 @@ import { applyFontSettings, applyTheme, type ThemeId } from "@pubscript/ui";
 
 export type Density = "compact" | "comfortable";
 
+/** Body typeface for the writing column. All are system stacks (no web fonts). */
+export type FontFamily = "serif" | "sans" | "mono";
+
+export const FONT_FAMILIES: { value: FontFamily; label: string; css: string }[] = [
+  { value: "serif", label: "Georgia Serif", css: 'Georgia, "Times New Roman", serif' },
+  { value: "sans", label: "System Sans", css: '-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif' },
+  { value: "mono", label: "Mono", css: '"SFMono-Regular", ui-monospace, "Cascadia Code", Consolas, monospace' },
+];
+
+/** Resolve a stored font-family enum to its CSS font-family string. */
+export function fontFamilyCss(value: FontFamily): string {
+  const found = FONT_FAMILIES.find((f) => f.value === value);
+  return found?.css ?? FONT_FAMILIES.at(0)?.css ?? "";
+}
+
 export interface AppSettings {
   theme: ThemeId;
   accentColor: string;
   density: Density;
+  fontFamily: FontFamily;
   fontSize: number;
+  leading: number;
+  measure: number;
   showLineNumbers: boolean;
   wordCountGoal: number;
   autoSave: boolean;
+  focusMode: boolean;
+  typewriterMode: boolean;
 }
 
 export const DEFAULT_SETTINGS: AppSettings = {
   theme: "ink",
   accentColor: "#7c8bf5",
   density: "comfortable",
+  fontFamily: "serif",
   fontSize: 15,
+  leading: 1.7,
+  measure: 720,
   showLineNumbers: true,
   wordCountGoal: 80_000,
   autoSave: true,
+  focusMode: false,
+  typewriterMode: false,
 };
 
 const STORAGE_KEY = "pubscript.settings.v1";
@@ -46,14 +71,31 @@ export const useSettings = create<SettingsStore>((set, get) => {
   const initial = loadSettings();
   // Apply the persisted theme + font on boot.
   applyTheme(initial.theme);
-  applyFontSettings({ size: initial.fontSize });
+  applyFontSettings({
+    size: initial.fontSize,
+    leading: initial.leading,
+    measure: initial.measure,
+    family: fontFamilyCss(initial.fontFamily),
+  });
 
   return {
     ...initial,
     set: (patch) => {
       const next = { ...get(), ...patch };
       localStorage.setItem(STORAGE_KEY, JSON.stringify(next));
-      if (patch.fontSize != null) applyFontSettings({ size: next.fontSize });
+      if (
+        patch.fontSize != null ||
+        patch.leading != null ||
+        patch.measure != null ||
+        patch.fontFamily != null
+      ) {
+        applyFontSettings({
+          size: next.fontSize,
+          leading: next.leading,
+          measure: next.measure,
+          family: fontFamilyCss(next.fontFamily),
+        });
+      }
       set(next);
     },
     setTheme: (theme) => {
@@ -63,7 +105,12 @@ export const useSettings = create<SettingsStore>((set, get) => {
     reset: () => {
       localStorage.removeItem(STORAGE_KEY);
       applyTheme(DEFAULT_SETTINGS.theme);
-      applyFontSettings({ size: DEFAULT_SETTINGS.fontSize });
+      applyFontSettings({
+        size: DEFAULT_SETTINGS.fontSize,
+        leading: DEFAULT_SETTINGS.leading,
+        measure: DEFAULT_SETTINGS.measure,
+        family: fontFamilyCss(DEFAULT_SETTINGS.fontFamily),
+      });
       set({ ...DEFAULT_SETTINGS });
     },
   };
diff --git a/apps/web/src/styles/entities.css b/apps/web/src/styles/entities.css
new file mode 100644
index 0000000..79e67c4
--- /dev/null
+++ b/apps/web/src/styles/entities.css
@@ -0,0 +1,466 @@
+/**
+ * Entity engine styles (apps/web).
+ *
+ * Styles for the Chunk #4 entity engine UI: the tabbed directory, the fuzzy
+ * search bar, the entity card grid, the create/edit drawer, the relationship
+ * editor, and the force-directed relationship map. These sit on top of the
+ * `@pubscript/ui` component kit (AppShell.css) and reuse its design tokens
+ * (`--ps-*`) and field/button/drawer/tabs/badge classes.
+ */
+
+/* Full-width container for the entity engine (overrides .ps-content narrowness). */
+.ps-entities-view {
+  height: 100%;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.ps-entities-view > .ps-tabs {
+  flex: 1;
+  overflow: hidden;
+  display: flex;
+  flex-direction: column;
+}
+
+/* ---- Search bar + new-entity actions ---- */
+.ps-entity-search {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  margin-bottom: 20px;
+  flex-wrap: wrap;
+}
+
+.ps-entity-search-input {
+  flex: 1;
+  min-width: 240px;
+}
+
+.ps-entity-new-group {
+  display: flex;
+  gap: 8px;
+}
+
+/* ---- Entity card grid ---- */
+.ps-entity-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
+  gap: 14px;
+  padding-bottom: 96px;
+}
+
+.ps-entity-card {
+  text-align: left;
+  border: 1px solid var(--ps-border);
+  border-radius: 10px;
+  padding: 14px 16px;
+  background: var(--ps-surface-2);
+  cursor: pointer;
+  transition: border-color 0.15s, transform 0.1s, box-shadow 0.15s;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  font-family: var(--ps-font-ui);
+}
+
+.ps-entity-card:hover {
+  border-color: var(--ps-accent);
+  transform: translateY(-2px);
+  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.08);
+}
+
+.ps-entity-card-top {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+}
+
+.ps-entity-type-badge {
+  font-size: 11px;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.04em;
+  padding: 2px 8px;
+  border-radius: 999px;
+  background: color-mix(in srgb, var(--ps-accent) 16%, transparent);
+  color: var(--ps-accent);
+}
+
+.ps-type-character {
+  background: color-mix(in srgb, var(--ps-accent) 16%, transparent);
+  color: var(--ps-accent);
+}
+
+.ps-type-worldItem {
+  background: color-mix(in srgb, #8a5cf5 16%, transparent);
+  color: #8a5cf5;
+}
+
+.ps-entity-card-name {
+  font-size: 16px;
+  font-weight: 600;
+  color: var(--ps-text);
+  margin: 0;
+  word-break: break-word;
+}
+
+.ps-entity-card-sub {
+  font-size: 13px;
+  color: var(--ps-text-muted);
+  margin: 0;
+}
+
+.ps-entity-card-tags {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 4px;
+  margin-top: 2px;
+}
+
+.ps-entity-tag {
+  font-size: 11px;
+  padding: 1px 7px;
+  border-radius: 999px;
+  background: var(--ps-surface);
+  color: var(--ps-text-muted);
+  border: 1px solid var(--ps-border);
+}
+
+/* ---- Relationship map ---- */
+.ps-entity-map {
+  padding: 8px;
+  display: flex;
+  justify-content: center;
+}
+
+.ps-relationship-map {
+  width: 100%;
+  max-width: 640px;
+  height: auto;
+  border: 1px solid var(--ps-border);
+  border-radius: 10px;
+  background: var(--ps-surface-2);
+}
+
+.ps-relationship-empty {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 420px;
+  color: var(--ps-text-muted);
+  font-size: 15px;
+}
+
+.ps-relationship-node {
+  transition: transform 0.1s;
+}
+
+.ps-relationship-label {
+  font-family: var(--ps-font-ui);
+}
+
+/* ---- Entity editor drawer ---- */
+.ps-entity-editor {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.ps-entity-editor-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-top: 12px;
+  padding-top: 16px;
+  border-top: 1px solid var(--ps-border);
+}
+
+.ps-spacer {
+  flex: 1;
+}
+
+.ps-entity-delete {
+  margin-right: auto;
+}
+
+/* ---- Generic entity fields ---- */
+.ps-entity-fields {
+  display: flex;
+  flex-direction: column;
+}
+
+.ps-field-span-2 {
+  grid-column: span 2;
+}
+
+.ps-textarea {
+  resize: vertical;
+  min-height: 60px;
+  font-family: var(--ps-font-ui);
+  line-height: 1.5;
+}
+
+.ps-field-checkbox {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  font-size: 14px;
+  color: var(--ps-text);
+}
+
+/* ---- Tag field ---- */
+.ps-tag-field {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.ps-tag-list {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 6px;
+}
+
+.ps-tag-chip {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  font-size: 12px;
+  padding: 2px 6px 2px 10px;
+  border-radius: 999px;
+  background: var(--ps-surface);
+  border: 1px solid var(--ps-border);
+  color: var(--ps-text);
+}
+
+.ps-tag-remove {
+  border: none;
+  background: none;
+  cursor: pointer;
+  color: var(--ps-text-muted);
+  font-size: 15px;
+  line-height: 1;
+  padding: 0 2px;
+}
+
+.ps-tag-remove:hover {
+  color: var(--ps-danger);
+}
+
+/* ---- Relationship editor ---- */
+.ps-relationship-editor {
+  margin-top: 8px;
+  padding-top: 16px;
+  border-top: 1px solid var(--ps-border);
+}
+
+.ps-relationship-list {
+  list-style: none;
+  margin: 8px 0 12px;
+  padding: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.ps-relationship-item {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 6px 10px;
+  background: var(--ps-surface-2);
+  border: 1px solid var(--ps-border);
+  border-radius: 8px;
+}
+
+.ps-relationship-kind {
+  font-size: 11px;
+  font-weight: 600;
+  text-transform: capitalize;
+  padding: 2px 8px;
+  border-radius: 999px;
+  background: color-mix(in srgb, var(--ps-accent) 16%, transparent);
+  color: var(--ps-accent);
+}
+
+.ps-relationship-target {
+  flex: 1;
+  font-size: 14px;
+  color: var(--ps-text);
+}
+
+.ps-relationship-remove {
+  border: none;
+  background: none;
+  cursor: pointer;
+  color: var(--ps-text-muted);
+  font-size: 18px;
+  line-height: 1;
+  padding: 0 4px;
+}
+
+.ps-relationship-remove:hover {
+  color: var(--ps-danger);
+}
+
+.ps-relationship-add {
+  display: flex;
+  gap: 8px;
+  flex-wrap: wrap;
+  align-items: center;
+}
+
+.ps-relationship-target-select,
+.ps-relationship-kind-select {
+  flex: 1;
+  min-width: 120px;
+}
+
+.ps-relationship-note {
+  flex: 2;
+  min-width: 120px;
+}
+
+/* ---- Misc ---- */
+.ps-muted {
+  color: var(--ps-text-muted);
+  font-size: 14px;
+}
+
+/* ---- Toolbar + tabs ---- */
+.ps-entity-toolbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  margin-bottom: 12px;
+  flex-wrap: wrap;
+}
+
+.ps-entity-tabs {
+  display: flex;
+  gap: 4px;
+  border-bottom: 1px solid var(--ps-border);
+  padding-bottom: -1px;
+}
+
+.ps-entity-tab {
+  background: none;
+  border: none;
+  padding: 8px 12px;
+  font-size: 14px;
+  font-family: var(--ps-font-ui);
+  color: var(--ps-text-muted);
+  cursor: pointer;
+  border-bottom: 2px solid transparent;
+  margin-bottom: -1px;
+  transition: color 0.15s, border-color 0.15s;
+}
+
+.ps-entity-tab:hover {
+  color: var(--ps-text);
+}
+
+.ps-entity-tab.active {
+  color: var(--ps-text);
+  border-bottom-color: var(--ps-accent);
+  font-weight: 600;
+}
+
+.ps-entity-new-kind {
+  min-width: 120px;
+}
+
+/* ---- Entity editor drawer header/body ---- */
+.ps-entity-editor-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 4px;
+}
+
+.ps-entity-editor-header h2 {
+  font-size: 16px;
+  font-weight: 600;
+  margin: 0;
+  color: var(--ps-text);
+}
+
+.ps-entity-editor-body {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+  overflow-y: auto;
+  padding: 4px 2px;
+}
+
+.ps-icon-btn {
+  border: none;
+  background: none;
+  font-size: 22px;
+  line-height: 1;
+  cursor: pointer;
+  color: var(--ps-text-muted);
+  padding: 0 4px;
+}
+
+.ps-icon-btn:hover {
+  color: var(--ps-text);
+}
+
+/* ---- Relationship section + map ---- */
+.ps-relationship-section {
+  margin-top: 8px;
+  padding-top: 16px;
+  border-top: 1px solid var(--ps-border);
+}
+
+.ps-relationship-section h3 {
+  font-size: 13px;
+  font-weight: 600;
+  text-transform: uppercase;
+  letter-spacing: 0.03em;
+  color: var(--ps-text-muted);
+  margin: 0 0 8px;
+}
+
+.ps-relationship-map-wrap {
+  margin-top: 12px;
+  display: flex;
+  justify-content: center;
+}
+
+.ps-relationship-svg {
+  width: 100%;
+  max-width: 520px;
+  height: auto;
+}
+
+.ps-relationship-map-empty {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  height: 200px;
+  color: var(--ps-text-muted);
+  font-size: 14px;
+}
+
+.ps-rel-edge {
+  stroke: var(--ps-border);
+  stroke-width: 1.5;
+}
+
+.ps-rel-node {
+  stroke: var(--ps-surface);
+  stroke-width: 2;
+  transition: transform 0.1s;
+}
+
+.ps-rel-node-label {
+  font-family: var(--ps-font-ui);
+  font-size: 10px;
+  fill: var(--ps-text-muted);
+  pointer-events: none;
+}
diff --git a/packages/core/src/autosave.test.ts b/packages/core/src/autosave.test.ts
index fb6acbe..27c6b4b 100644
--- a/packages/core/src/autosave.test.ts
+++ b/packages/core/src/autosave.test.ts
@@ -29,6 +29,16 @@ function mockAdapter(): StorageAdapter & { saved: DocumentRef[] } {
       return null;
     },
     async saveEntity() {},
+    async listEntities() {
+      return [];
+    },
+    async getEntity() {
+      return null;
+    },
+    async deleteEntity() {},
+    async searchEntities() {
+      return [];
+    },
     async saveBoard() {},
     async saveAISession() {},
     async saveDocument(doc: DocumentRef) {
diff --git a/packages/core/src/backlinks.ts b/packages/core/src/backlinks.ts
index 225f68f..0565fbc 100644
--- a/packages/core/src/backlinks.ts
+++ b/packages/core/src/backlinks.ts
@@ -82,3 +82,21 @@ export function docHasMentions(doc: ProseMirrorDoc): boolean {
   visit(doc.content ?? []);
   return found;
 }
+
+/**
+ * Compute the backlinks for a single entity across a set of chapters: every
+ * chapter that references it, with the node paths where it appears.
+ */
+export function backlinksForEntity(
+  chapters: Array<{ id: string; title: string; doc: ProseMirrorDoc }>,
+  entityId: string,
+): Backlink[] {
+  const links: Backlink[] = [];
+  for (const ch of chapters) {
+    const paths = findMentionsInDoc(ch.doc, new Set([entityId]), new Set());
+    if (paths.length > 0) {
+      links.push({ chapterId: ch.id, title: ch.title, paths });
+    }
+  }
+  return links;
+}
diff --git a/packages/core/src/consistency.test.ts b/packages/core/src/consistency.test.ts
new file mode 100644
index 0000000..ca38da8
--- /dev/null
+++ b/packages/core/src/consistency.test.ts
@@ -0,0 +1,171 @@
+import { describe, it, expect } from "vitest";
+import {
+  findOrphanedMentions,
+  parseRelationships,
+  findRelationshipAsymmetry,
+  findInconsistencies,
+  SYMMETRIC_RELATIONSHIPS,
+} from "./consistency.js";
+import type { Character, Entity, ProseMirrorDoc } from "./types.js";
+
+const doc = (entityId: string | null, name = "Mara"): ProseMirrorDoc => ({
+  type: "doc",
+  content: [
+    {
+      type: "paragraph",
+      content: [
+        { type: "text", text: "She said " },
+        { type: "CharacterMention", attrs: entityId ? { entityId, name } : { name } },
+      ],
+    },
+  ],
+});
+
+describe("findOrphanedMentions", () => {
+  it("flags a mention whose entity id is gone", () => {
+    const chapters = [{ id: "ch1", title: "Ch 1", doc: doc("ghost") }];
+    const issues = findOrphanedMentions(chapters, new Set(["ada"]));
+    expect(issues).toHaveLength(1);
+    expect(issues[0]).toMatchObject({ kind: "orphan-mention", entityId: "ghost", chapterId: "ch1" });
+  });
+
+  it("does not flag a mention whose entity still exists", () => {
+    const chapters = [{ id: "ch1", title: "Ch 1", doc: doc("ada") }];
+    expect(findOrphanedMentions(chapters, new Set(["ada"]))).toHaveLength(0);
+  });
+
+  it("does not flag a bare name mention (no entityId)", () => {
+    const chapters = [{ id: "ch1", title: "Ch 1", doc: doc(null) }];
+    expect(findOrphanedMentions(chapters, new Set(["ada"]))).toHaveLength(0);
+  });
+});
+
+describe("parseRelationships", () => {
+  it("parses the relationships array into a targetId map", () => {
+    const c: Character = {
+      id: "ada",
+      projectId: "p",
+      name: "Ada",
+      role: "",
+      bio: "",
+      appearance: "",
+      voice: "",
+      relationships: [
+        { targetId: "maria", kind: "sibling", note: "sisters" },
+        { targetId: "mark", kind: "ally", note: "" },
+      ],
+      arc: "",
+      status: "active",
+      tags: [],
+    };
+    expect(parseRelationships(c)).toEqual({
+      maria: { kind: "sibling", note: "sisters" },
+      mark: { kind: "ally", note: "" },
+    });
+  });
+});
+
+describe("findRelationshipAsymmetry", () => {
+  const ada: Character = {
+    id: "ada",
+    projectId: "p",
+    name: "Ada",
+    role: "",
+    bio: "",
+    appearance: "",
+    voice: "",
+    relationships: [{ targetId: "maria", kind: "sibling", note: "" }],
+    arc: "",
+    status: "active",
+    tags: [],
+  };
+  const maria: Character = {
+    id: "maria",
+    projectId: "p",
+    name: "Maria",
+    role: "",
+    bio: "",
+    appearance: "",
+    voice: "",
+    relationships: [],
+    arc: "",
+    status: "active",
+    tags: [],
+  };
+  const brad: Character = {
+    id: "brad",
+    projectId: "p",
+    name: "Brad",
+    role: "",
+    bio: "",
+    appearance: "",
+    voice: "",
+    relationships: [{ targetId: "ada", kind: "rival", note: "" }],
+    arc: "",
+    status: "active",
+    tags: [],
+  };
+  const adaBack: Character = {
+    ...ada,
+    relationships: [
+      { targetId: "maria", kind: "sibling", note: "" },
+      { targetId: "brad", kind: "rival", note: "" },
+    ],
+  };
+
+  it("reports a symmetric relationship that is not reciprocated", () => {
+    const issues = findRelationshipAsymmetry([ada, maria]);
+    expect(issues).toHaveLength(1);
+    expect(issues[0]).toMatchObject({ kind: "relationship-asymmetry", fromEntity: "ada", toEntity: "maria", relationship: "sibling" });
+  });
+
+  it("does not report when the symmetric relationship is reciprocated", () => {
+    const mariaBack: Character = {
+      ...maria,
+      relationships: [{ targetId: "ada", kind: "sibling", note: "" }],
+    };
+    const issues = findRelationshipAsymmetry([adaBack, mariaBack, brad]);
+    expect(issues).toHaveLength(0);
+  });
+
+  it("ignores directed (non-symmetric) relationship kinds", () => {
+    const mentor: Character = {
+      id: "m",
+      projectId: "p",
+      name: "Mentor",
+      role: "",
+      bio: "",
+      appearance: "",
+      voice: "",
+      relationships: [{ targetId: "ada", kind: "mentor", note: "" }],
+      arc: "",
+      status: "active",
+      tags: [],
+    };
+    expect(findRelationshipAsymmetry([ada, mentor])).toHaveLength(0);
+  });
+
+  it("exposes the symmetric kinds", () => {
+    expect(SYMMETRIC_RELATIONSHIPS.has("sibling")).toBe(true);
+    expect(SYMMETRIC_RELATIONSHIPS.has("mentor")).toBe(false);
+  });
+});
+
+describe("findInconsistencies", () => {
+  it("combines orphan-mention and relationship-asymmetry issues", () => {
+    const chapters = [{ id: "ch1", title: "Ch 1", doc: doc("ghost") }];
+    const ada: Character = {
+      id: "ada", projectId: "p", name: "Ada", role: "", bio: "", appearance: "", voice: "",
+      relationships: [{ targetId: "maria", kind: "sibling", note: "" }],
+      arc: "", status: "active", tags: [],
+    };
+    const maria: Character = {
+      id: "maria", projectId: "p", name: "Maria", role: "", bio: "", appearance: "", voice: "",
+      relationships: [], arc: "", status: "active", tags: [],
+    };
+    const entities: Entity[] = [ada, maria];
+    const issues = findInconsistencies(chapters, entities);
+    expect(issues.some((i) => i.kind === "orphan-mention")).toBe(true);
+    expect(issues.some((i) => i.kind === "relationship-asymmetry")).toBe(true);
+  });
+});
diff --git a/packages/core/src/consistency.ts b/packages/core/src/consistency.ts
new file mode 100644
index 0000000..2c51986
--- /dev/null
+++ b/packages/core/src/consistency.ts
@@ -0,0 +1,130 @@
+/**
+ * Consistency checks across entities and chapters. These catch the kinds of
+ * contradictions that creep in as a manuscript grows: a character mentioned in
+ * prose whose entity was deleted, or a relationship that only one side records.
+ * See CHUNK #4 step 2.4.
+ */
+import type { Character, Entity, ProseMirrorDoc } from "./types.js";
+
+export type RelationshipSymmetry = "symmetric" | "directed";
+
+/**
+ * Relationship kinds that should hold in both directions. If Ada lists "Bram:
+ * sibling", then Bram should list "Ada: sibling" too.
+ */
+export const SYMMETRIC_RELATIONSHIPS = new Set(["sibling", "friend", "spouse", "partner", "family", "rival"]);
+
+export interface MentionIssue {
+  kind: "orphan-mention";
+  chapterId: string;
+  chapterTitle: string;
+  entityId: string;
+  /** The mention text, if any. */
+  name?: string | undefined;
+}
+
+export interface RelationshipIssue {
+  kind: "relationship-asymmetry";
+  fromEntity: string;
+  fromName: string;
+  toEntity: string;
+  toName: string;
+  relationship: string;
+}
+
+export type ConsistencyIssue = MentionIssue | RelationshipIssue;
+
+/**
+ * Find mention nodes that reference an entity id that no longer exists (e.g.
+ * the entity was deleted). Returns one issue per offending mention.
+ */
+export function findOrphanedMentions(
+  chapters: Array<{ id: string; title: string; doc: ProseMirrorDoc }>,
+  entityIds: Set<string>,
+): MentionIssue[] {
+  const issues: MentionIssue[] = [];
+  for (const ch of chapters) {
+    const visit = (content: unknown[], _path: number[]): void => {
+      for (const node of content as Record<string, unknown>[]) {
+        if (!node || typeof node !== "object") continue;
+        if (node.type === "CharacterMention") {
+          const attrs = node.attrs as { entityId?: string; name?: string } | undefined;
+          if (attrs?.entityId && !entityIds.has(attrs.entityId)) {
+            issues.push({
+              kind: "orphan-mention",
+              chapterId: ch.id,
+              chapterTitle: ch.title,
+              entityId: attrs.entityId,
+              name: attrs.name,
+            });
+          }
+        }
+        if (Array.isArray(node.content)) visit(node.content as unknown[], _path);
+      }
+    };
+    visit(ch.doc.content ?? [], []);
+  }
+  return issues;
+}
+
+/**
+ * Parse the `relationships` array of a character into
+ * `{ [targetId]: { kind, note } }`.
+ */
+export function parseRelationships(character: Character): Record<string, { kind: string; note: string }> {
+  const out: Record<string, { kind: string; note: string }> = {};
+  for (const r of character.relationships ?? []) {
+    out[r.targetId] = { kind: r.kind, note: r.note };
+  }
+  return out;
+}
+
+/**
+ * Find relationships recorded by one character but not reciprocated by the
+ * other, for symmetric relationship kinds. Returns one issue per asymmetric
+ * pair (reported once, from the recording side).
+ */
+export function findRelationshipAsymmetry(entities: Entity[]): RelationshipIssue[] {
+  const characters = entities.filter((e): e is Character => !("fields" in e) && !("body" in e));
+  // index by id -> character (targetId is an entity id)
+  const byId = new Map<string, Character>();
+  for (const c of characters) byId.set(c.id, c);
+
+  const issues: RelationshipIssue[] = [];
+  for (const c of characters) {
+    const rels = parseRelationships(c);
+    for (const [targetId, rel] of Object.entries(rels)) {
+      const sym = rel.kind.toLowerCase();
+      if (!SYMMETRIC_RELATIONSHIPS.has(sym)) continue;
+      const other = byId.get(targetId);
+      if (!other || other.id === c.id) continue;
+      // Does the other side record this character back with a symmetric kind?
+      const otherRel = parseRelationships(other);
+      const back = otherRel[c.id];
+      if (!back || !SYMMETRIC_RELATIONSHIPS.has(back.kind.toLowerCase())) {
+        issues.push({
+          kind: "relationship-asymmetry",
+          fromEntity: c.id,
+          fromName: c.name,
+          toEntity: other.id,
+          toName: other.name,
+          relationship: rel.kind,
+        });
+      }
+    }
+  }
+  return issues;
+}
+
+/** Run every consistency check and return the combined issue list. */
+export function findInconsistencies(
+  chapters: Array<{ id: string; title: string; doc: ProseMirrorDoc }>,
+  entities: Entity[],
+): ConsistencyIssue[] {
+  const entityIds = new Set(entities.map((e) => e.id));
+  const issues: ConsistencyIssue[] = [
+    ...findOrphanedMentions(chapters, entityIds),
+    ...findRelationshipAsymmetry(entities),
+  ];
+  return issues;
+}
diff --git a/packages/core/src/fuzzy.test.ts b/packages/core/src/fuzzy.test.ts
new file mode 100644
index 0000000..5cd7f28
--- /dev/null
+++ b/packages/core/src/fuzzy.test.ts
@@ -0,0 +1,75 @@
+import { describe, it, expect } from "vitest";
+import { fuzzyScore, fuzzyMatch, fuzzySort } from "./fuzzy.js";
+
+describe("fuzzyScore", () => {
+  it("matches an empty query as no-match (score 0)", () => {
+    expect(fuzzyScore("", "mara").score).toBe(0);
+  });
+
+  it("matches a whole-string query at score 1", () => {
+    const r = fuzzyScore("mara", "Mara");
+    expect(r.score).toBe(1);
+    expect(r.indices).toEqual([0, 1, 2, 3]);
+  });
+
+  it("matches a subsequence in order", () => {
+    const r = fuzzyScore("mr", "Mara");
+    expect(r.score).toBeGreaterThan(0);
+    expect(r.indices).toEqual([0, 2]);
+  });
+
+  it("does not match a non-subsequence", () => {
+    expect(fuzzyScore("z", "Mara").score).toBe(0);
+    expect(fuzzyScore("marz", "Mara").score).toBe(0);
+  });
+
+  it("scores consecutive matches higher than scattered ones", () => {
+    const consecutive = fuzzyScore("mar", "maria").score;
+    const scattered = fuzzyScore("mr", "maria").score;
+    expect(consecutive).toBeGreaterThan(scattered);
+  });
+
+  it("scores word-start matches higher", () => {
+    const wordStart = fuzzyScore("h", "harbor").score;
+    const mid = fuzzyScore("r", "harbor").score;
+    expect(wordStart).toBeGreaterThan(mid);
+  });
+});
+
+describe("fuzzyMatch", () => {
+  it("is true for a subsequence and false otherwise", () => {
+    expect(fuzzyMatch("mr", "Mara")).toBe(true);
+    expect(fuzzyMatch("z", "Mara")).toBe(false);
+  });
+});
+
+describe("fuzzySort", () => {
+  const items = [
+    { id: "ada", name: "Ada Lovelace" },
+    { id: "maria", name: "Maria Harbor" },
+    { id: "mark", name: "Mark Twain" },
+  ];
+
+  it("returns all items for an empty query, preserving order", () => {
+    expect(fuzzySort(items, "", (i) => i.name).map((i) => i.id)).toEqual(["ada", "maria", "mark"]);
+  });
+
+  it("drops non-matches and orders by descending score", () => {
+    const sorted = fuzzySort(items, "mar", (i) => i.name);
+    expect(sorted.map((i) => i.id)).toContain("maria");
+    expect(sorted.map((i) => i.id)).not.toContain("ada");
+    // "Maria Harbor" (word start) should beat "Mark Twain" (word start) only on tie-break; both match.
+    expect(sorted.length).toBe(2);
+  });
+
+  it("is stable for equal scores", () => {
+    // "ada" and "amy" both score 2 for query "a" (word-start match); input
+    // order must be preserved.
+    const stable = [
+      { id: "a", name: "ada" },
+      { id: "b", name: "amy" },
+    ];
+    const sorted = fuzzySort(stable, "a", (i) => i.name);
+    expect(sorted.map((i) => i.id)).toEqual(["a", "b"]);
+  });
+});
diff --git a/packages/core/src/fuzzy.ts b/packages/core/src/fuzzy.ts
new file mode 100644
index 0000000..2d17ed3
--- /dev/null
+++ b/packages/core/src/fuzzy.ts
@@ -0,0 +1,111 @@
+/**
+ * Dependency-light fuzzy scorer used for entity search and mention
+ * autocomplete.
+ *
+ * This is a subsequence scorer in the spirit of "sublime" / Fuse.js: a query is
+ * a sequence of characters that must appear (in order) within a target string.
+ * It scores matches so that:
+ *
+ *   - consecutive matches score higher than scattered ones,
+ *   - matches at the start of a word (after a separator) score higher,
+ *   - earlier matches in the string score higher.
+ *
+ * The result is a number in `[0, 1]` where `1` is a perfect (whole-string,
+ * case-insensitive, consecutive) match. It is intentionally allocation-light
+ * and fast enough to run on every keystroke against a few hundred entities
+ * well under the 50 ms budget the plan calls for.
+ */
+
+const WORD_SEP = /[^a-zA-Z0-9]+/;
+
+export interface FuzzyResult {
+  /** Match score in [0, 1]; 0 means no match. */
+  score: number;
+  /** Indices in `target` that were matched by the query, in order. */
+  indices: number[];
+}
+
+/** Score a single matched cell from its predecessor score. */
+function scoreCell(prev: number, consecutive: number, wordStart: number): number {
+  let s = prev + 1; // base reward for a match
+  if (consecutive) s *= 1.4; // multiplicative streak bonus
+  if (wordStart) s += 0.8; // word-start bonus
+  return s;
+}
+
+/** Normalize a raw score into [0, 1]. */
+function normalize(raw: number): number {
+  if (!isFinite(raw)) return 0;
+  return Math.max(0, Math.min(1, raw / 3));
+}
+
+/**
+ * Score `query` against `target`. Returns `{ score: 0 }` when the query is not a
+ * subsequence of the target (i.e. no match).
+ */
+export function fuzzyScore(query: string, target: string): FuzzyResult {
+  const q = query;
+  const t = target;
+  if (q.length === 0) return { score: 0, indices: [] };
+  if (q.length > t.length) return { score: 0, indices: [] };
+
+  const ql = q.length;
+  const tl = t.length;
+  const tq = q.toLowerCase();
+  const tt = t.toLowerCase();
+
+  // best[i] = best score having matched the first i query chars.
+  // where[i] = target index at which the i-th match landed (for recovery).
+  const best = new Float64Array(ql + 1).fill(-Infinity);
+  const where = new Int32Array(ql + 1);
+  const consec = new Uint8Array(ql + 1);
+  best[0] = 0;
+
+  for (let ti = 0; ti < tl; ti++) {
+    const tc = tt[ti]!;
+    // Walk from high to low so each cell reads the previous row only.
+    for (let i = ql; i >= 1; i--) {
+      const qc = tq[i - 1]!;
+      if (tc !== qc) continue;
+      const fromPrev = best[i - 1]!;
+      if (fromPrev <= -Infinity) continue;
+      const wordStart = ti === 0 || WORD_SEP.test(t[ti - 1]!) ? 1 : 0;
+      const c = consec[i - 1] ? 1 : 0;
+      const s = scoreCell(fromPrev, c, wordStart);
+      if (s > best[i]!) {
+        best[i] = s;
+        where[i] = ti;
+        consec[i] = c;
+      }
+    }
+  }
+
+  if (best[ql]! <= -Infinity) return { score: 0, indices: [] };
+
+  // Recover matched indices by walking `where` backwards.
+  const indices: number[] = [];
+  for (let i = ql; i >= 1; i--) {
+    indices.push(where[i]!);
+  }
+  indices.reverse();
+
+  return { score: normalize(best[ql]!), indices };
+}
+
+/** Convenience: does `query` match `target` as a subsequence? */
+export function fuzzyMatch(query: string, target: string): boolean {
+  return fuzzyScore(query, target).score > 0;
+}
+
+/**
+ * Sort `items` by descending fuzzy score against `query`, dropping non-matches.
+ * Stable: equal scores keep input order.
+ */
+export function fuzzySort<T>(items: T[], query: string, pick: (item: T) => string): T[] {
+  if (!query) return items.slice();
+  const scored = items
+    .map((item) => ({ item, res: fuzzyScore(query, pick(item)) }))
+    .filter((r) => r.res.score > 0);
+  scored.sort((a, b) => b.res.score - a.res.score);
+  return scored.map((r) => r.item);
+}
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 737e543..8128673 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -12,4 +12,6 @@ export * from "./schema.js";
 export * from "./schemas.js";
 export * from "./autosave.js";
 export * from "./backlinks.js";
+export * from "./fuzzy.js";
+export * from "./consistency.js";
 export * from "./storage-server.js";
diff --git a/packages/core/src/storage-local.ts b/packages/core/src/storage-local.ts
index e1d28f2..76e6418 100644
--- a/packages/core/src/storage-local.ts
+++ b/packages/core/src/storage-local.ts
@@ -13,6 +13,7 @@ import type {
 import type { StorageAdapter } from "./storage.js";
 import { createUlid } from "./ids.js";
 import { nowIso } from "./time.js";
+import { fuzzySort } from "./fuzzy.js";
 
 interface EntityRec {
   key: string;
@@ -49,6 +50,35 @@ const entityKey = (projectId: string, kind: string, id: string): string =>
 const kindOf = (e: Entity): string =>
   "fields" in e ? "world" : "body" in e ? "note" : "character";
 
+/**
+ * Concatenate every human-readable field of an entity into a single searchable
+ * string (name + field values). Used by the fuzzy search index.
+ */
+function entitySearchText(e: Entity): string {
+  if ("fields" in e) {
+    // WorldItem
+    const parts = [e.name, e.kind];
+    for (const v of Object.values(e.fields)) if (typeof v === "string") parts.push(v);
+    return parts.join(" ");
+  }
+  if ("body" in e) {
+    // Note
+    return [e.body, ...e.tags].join(" ");
+  }
+  // Character
+  return [
+    e.name,
+    e.role,
+    e.bio,
+    e.appearance,
+    e.voice,
+    e.relationships,
+    e.arc,
+    e.status,
+    ...e.tags,
+  ].join(" ");
+}
+
 /**
  * The local (offline-first) `StorageAdapter`, backed by IndexedDB via Dexie.
  * Implements the exact `StorageAdapter` contract so the app can run fully
@@ -136,6 +166,30 @@ export const storageLocal: StorageAdapter = {
     await db.entities.put({ key: entityKey(e.projectId, kind, e.id), projectId: e.projectId, kind, data: e });
   },
 
+  async listEntities(projectId: string, kind?: string): Promise<Entity[]> {
+    const rows = await db.entities
+      .where("projectId")
+      .equals(projectId)
+      .toArray();
+    const filtered = kind ? rows.filter((r) => r.kind === kind) : rows;
+    return filtered.map((r) => r.data);
+  },
+
+  async getEntity(projectId: string, kind: string, id: string): Promise<Entity | null> {
+    const row = await db.entities.get(entityKey(projectId, kind, id));
+    return row ? row.data : null;
+  },
+
+  async deleteEntity(projectId: string, kind: string, id: string): Promise<void> {
+    await db.entities.delete(entityKey(projectId, kind, id));
+  },
+
+  async searchEntities(projectId: string, q: string): Promise<Entity[]> {
+    const all = await this.listEntities(projectId);
+    if (!q) return all;
+    return fuzzySort(all, q, entitySearchText);
+  },
+
   async saveBoard(b: Board): Promise<void> {
     await db.boards.put(b);
   },
diff --git a/packages/core/src/storage-server.ts b/packages/core/src/storage-server.ts
index d048fed..3bb6ddb 100644
--- a/packages/core/src/storage-server.ts
+++ b/packages/core/src/storage-server.ts
@@ -118,6 +118,41 @@ export function createServerClient(opts: ServerClientOptions): StorageAdapter {
       }
     },
 
+    async listEntities(projectId: string, kind?: string): Promise<Entity[]> {
+      const params = new URLSearchParams();
+      if (kind) params.set("kind", kind);
+      const qs = params.toString();
+      const res = await req<{ entities: Entity[] }>(
+        "GET",
+        `/api/projects/${projectId}/entities${qs ? `?${qs}` : ""}`,
+      );
+      return res.entities;
+    },
+
+    async getEntity(projectId: string, kind: string, id: string): Promise<Entity | null> {
+      try {
+        const res = await req<{ entity: Entity }>(
+          "GET",
+          `/api/projects/${projectId}/entities/${kind}/${id}`,
+        );
+        return res.entity;
+      } catch {
+        return null;
+      }
+    },
+
+    async deleteEntity(projectId: string, kind: string, id: string): Promise<void> {
+      await req("DELETE", `/api/projects/${projectId}/entities/${kind}/${id}`);
+    },
+
+    async searchEntities(projectId: string, q: string): Promise<Entity[]> {
+      const res = await req<{ entities: Entity[] }>(
+        "GET",
+        `/api/projects/${projectId}/entities?q=${encodeURIComponent(q)}`,
+      );
+      return res.entities;
+    },
+
     async saveBoard(b: Board): Promise<void> {
       await req("POST", `/api/projects/${b.projectId}/boards`, {
         id: b.id,
diff --git a/packages/core/src/storage.contract.test.ts b/packages/core/src/storage.contract.test.ts
index fb3756b..ce1ca60 100644
--- a/packages/core/src/storage.contract.test.ts
+++ b/packages/core/src/storage.contract.test.ts
@@ -1,6 +1,6 @@
 import "fake-indexeddb/auto";
 import { describe, expect, it } from "vitest";
-import { createServerClient, type ProseMirrorDoc, type StorageAdapter } from "@pubscript/core";
+import { createServerClient, type ProseMirrorDoc, type Character, type StorageAdapter, type WorldItem } from "@pubscript/core";
 import { storageLocal } from "@pubscript/core/local";
 
 const doc = (text: string): ProseMirrorDoc => ({ type: "doc", content: [{ type: "text", text }] });
@@ -63,6 +63,31 @@ function mockServerFetch(): typeof fetch {
       entities.set(`${m[1]!}|${body.kind}|${e.id}`, e);
       return json({ entity: e });
     }
+    if (method === "GET" && m) {
+      const projectId = m[1]!;
+      const kind = u.searchParams.get("kind");
+      const q = u.searchParams.get("q") ?? "";
+      const all = [...entities.values()].filter((e) => e.projectId === projectId && (!kind || e.kind === kind));
+      const filtered = q
+        ? all.filter((e) => JSON.stringify(e).toLowerCase().includes(q.toLowerCase()))
+        : all;
+      return json({ entities: filtered });
+    }
+    m = u.pathname.match(/^\/api\/projects\/([^/]+)\/entities\/([^/]+)\/([^/]+)$/);
+    if (method === "GET" && m) {
+      const projectId = m[1]!;
+      const kind = m[2]!;
+      const id = m[3]!;
+      const e = entities.get(`${projectId}|${kind}|${id}`);
+      return e ? json({ entity: e }) : json({ error: "not_found" }, 404);
+    }
+    if (method === "DELETE" && m) {
+      const projectId = m[1]!;
+      const kind = m[2]!;
+      const id = m[3]!;
+      entities.delete(`${projectId}|${kind}|${id}`);
+      return json({ ok: true });
+    }
     m = u.pathname.match(/^\/api\/projects\/([^/]+)\/boards$/);
     if (method === "POST" && m) {
       const b = { id: body.id ?? id(), projectId: m[1]!, nodes: body.nodes ?? [], edges: body.edges ?? [] };
@@ -132,6 +157,85 @@ const EXPECTED = {
   chapterRev: 1,
 };
 
+/** Entity CRUD + search scenario both adapters must pass identically. */
+async function entityScenario(adapter: StorageAdapter) {
+  const projectId = "proj-ent";
+  await adapter.createProject({ title: "Entities" });
+
+  const ada: Character = {
+    id: "ada",
+    projectId,
+    name: "Ada Lovelace",
+    role: "protagonist",
+    bio: "A mathematician and first computer programmer.",
+    appearance: "sharp eyes, Victorian dress",
+    voice: "precise, confident",
+    relationships: [{ targetId: "babbage", kind: "ally", note: "worked together" }],
+    arc: "From curiosity to genius.",
+    status: "active",
+    tags: ["math", "victorian"],
+  };
+  const babbage: Character = {
+    id: "babbage",
+    projectId,
+    name: "Charles Babbage",
+    role: "mentor",
+    bio: "An obsessed inventor of computing machines.",
+    appearance: "bearded, bespectacled",
+    voice: "grumbly",
+    relationships: [],
+    arc: "",
+    status: "active",
+    tags: ["inventor"],
+  };
+  const clocktower: WorldItem = {
+    id: "clocktower",
+    projectId,
+    kind: "location",
+    name: "The Clocktower",
+    fields: { era: "1840s", significance: "meeting place" },
+  };
+
+  await adapter.saveEntity(ada);
+  await adapter.saveEntity(babbage);
+  await adapter.saveEntity(clocktower);
+
+  // list all
+  const all = await adapter.listEntities(projectId);
+  expect(all.map((e) => e.id).sort()).toEqual(["ada", "babbage", "clocktower"]);
+
+  // list by kind
+  const chars = await adapter.listEntities(projectId, "character");
+  expect(chars.map((e) => e.id).sort()).toEqual(["ada", "babbage"]);
+
+  // getEntity: found
+  expect(((await adapter.getEntity(projectId, "character", "ada")) as Character | null)?.name).toBe("Ada Lovelace");
+
+  // getEntity: not found
+  expect(await adapter.getEntity(projectId, "character", "nope")).toBeNull();
+
+  // search: fuzzy match, best-first
+  const babbageRes = await adapter.searchEntities(projectId, "babbage");
+  expect(babbageRes.map((e) => e.id)).toContain("babbage");
+  const adaRes = await adapter.searchEntities(projectId, "ada");
+  expect(adaRes[0]?.id).toBe("ada");
+
+  // search: empty returns all
+  expect((await adapter.searchEntities(projectId, "")).length).toBe(3);
+
+  // delete
+  await adapter.deleteEntity(projectId, "character", "ada");
+  expect(await adapter.getEntity(projectId, "character", "ada")).toBeNull();
+  expect((await adapter.listEntities(projectId)).map((e) => e.id)).toEqual(["babbage", "clocktower"]);
+}
+
+describe.each([
+  { name: "local (IndexedDB)", adapter: storageLocal },
+  { name: "server (REST)", adapter: createServerClient({ baseUrl: "http://test", fetch: mockServerFetch() }) },
+])("$name adapter honors the entity contract", async ({ adapter }) => {
+  it("lists, fetches, searches, and deletes entities", () => entityScenario(adapter));
+});
+
 describe("StorageAdapter contract (web/local vs server)", () => {
   it("local (IndexedDB) adapter honors the contract", async () => {
     await expect(runScenario(storageLocal)).resolves.toMatchObject(EXPECTED);
diff --git a/packages/core/src/storage.ts b/packages/core/src/storage.ts
index 6de886f..3ef3e0b 100644
--- a/packages/core/src/storage.ts
+++ b/packages/core/src/storage.ts
@@ -40,6 +40,18 @@ export interface StorageAdapter {
   saveDocument(doc: DocumentRef): Promise<void>;
   getChapter(id: string): Promise<Chapter | null>;
   saveEntity(e: Entity): Promise<void>;
+  /**
+   * List entities for a project, optionally filtered by kind ("character" |
+   * "world" | "note"). Returns every entity when `kind` is omitted.
+   */
+  listEntities(projectId: string, kind?: string): Promise<Entity[]>;
+  getEntity(projectId: string, kind: string, id: string): Promise<Entity | null>;
+  deleteEntity(projectId: string, kind: string, id: string): Promise<void>;
+  /**
+   * Fuzzy search across an entity's name and field values. Returns matches
+   * ordered best-first; empty `q` returns all entities for the project.
+   */
+  searchEntities(projectId: string, q: string): Promise<Entity[]>;
   saveBoard(b: Board): Promise<void>;
   saveAISession(s: AISession): Promise<void>;
 
diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 7e1c40b..a84ae00 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -130,6 +130,10 @@ export type RelationshipKind =
   | "ally"
   | "rival"
   | "family"
+  | "sibling"
+  | "friend"
+  | "spouse"
+  | "partner"
   | "mentor"
   | "romantic"
   | "custom";
@@ -141,7 +145,7 @@ export interface WorldItem {
   projectId: string;
   kind: WorldItemKind;
   name: string;
-  fields: Record<string, string>;
+  fields: Record<string, string | string[]>;
 }
 
 export type BeatTemplate =
diff --git a/packages/editor/src/index.ts b/packages/editor/src/index.ts
index 3ea03e3..6b50938 100644
--- a/packages/editor/src/index.ts
+++ b/packages/editor/src/index.ts
@@ -44,6 +44,10 @@ export { serializeToMarkdown, parseMarkdown, markdownInputRules, markdownPasteRu
 
 export { throttle, createIdleDetector } from "./perf.js";
 
+export { MentionAutocomplete, mentionPickerState, findMentionTrigger } from "./mention.js";
+export type { MentionEntity, MentionProvider, MentionPickerState } from "./mention.js";
+export { MentionPicker } from "./nodes/MentionPicker.js";
+
 // Re-export the TipTap render surface and editor type so consumers of the
 // package never import TipTap directly.
 export { EditorContent } from "@tiptap/react";
diff --git a/packages/editor/src/mention.ts b/packages/editor/src/mention.ts
new file mode 100644
index 0000000..8c5c66a
--- /dev/null
+++ b/packages/editor/src/mention.ts
@@ -0,0 +1,115 @@
+/**
+ * Mention autocomplete — the `@` trigger that opens an entity picker and
+ * inserts a `CharacterMention` node.
+ *
+ * The editor package owns the low-level mechanics (detecting `@query`,
+ * positioning the picker, inserting the mention atom). The *data* — which
+ * entities to search — is injected by the app through a `MentionProvider`, so
+ * this package never imports the app's entity store.
+ *
+ * The picker is a React component (`MentionPicker`) that reads a small
+ * module-level `mentionPickerState` object shared with this extension. The
+ * extension exposes an `insertMention` command; the picker calls it on Enter.
+ */
+import { Extension, type Editor, type RawCommands } from "@tiptap/core";
+import type { Node } from "@tiptap/pm/model";
+import { CHARACTER_MENTION } from "./constants.js";
+
+/** A single entity option shown in the autocomplete picker. */
+export interface MentionEntity {
+  id: string;
+  label: string;
+  /** Optional subtitle (role / one-line bio) shown under the name. */
+  subtitle?: string;
+}
+
+/**
+ * The search provider the app injects. Given a query, return matching
+ * entities sorted by relevance (best first). An empty query should return the
+ * full list (or a capped prefix) so the picker shows candidates immediately.
+ */
+export interface MentionProvider {
+  search: (query: string) => MentionEntity[];
+}
+
+/**
+ * Shared picker state between the extension and the React picker. Kept at module
+ * scope because the TipTap extension is a singleton and the picker is rendered
+ * by the app alongside the editor — there is no cleaner channel between them.
+ */
+export interface MentionPickerState {
+  open: boolean;
+  query: string;
+  /** Doc position of the `@` trigger (where the mention will be inserted). */
+  atPos: number;
+  /** Cursor position (end of the query). */
+  from: number;
+  /** Currently highlighted result index. */
+  selectedIndex: number;
+}
+
+export const mentionPickerState: MentionPickerState = {
+  open: false,
+  query: "",
+  atPos: 0,
+  from: 0,
+  selectedIndex: 0,
+};
+
+/**
+ * Walk backwards from `from` over the doc text looking for the `@` trigger.
+ * Returns the trigger position, or `-1` when the text before the cursor is not
+ * a live mention query (no `@`, or a space/newline interrupts it).
+ */
+export function findMentionTrigger(doc: Node, from: number): number {
+  let atPos = from;
+  while (atPos > 0) {
+    const ch = doc.textBetween(atPos - 1, atPos) ?? "";
+    if (ch === "@") return atPos - 1;
+    if (ch === " " || ch === "\n" || ch === "\t") return -1;
+    atPos -= 1;
+  }
+  return -1;
+}
+
+/**
+ * The autocomplete extension. Adds the `insertMention` command used by the
+ * picker and (optionally) a keyboard shortcut to open the picker manually.
+ */
+export const MentionAutocomplete = Extension.create({
+  name: "mentionAutocomplete",
+
+  addOptions() {
+    return {
+      /** The trigger character. */
+      trigger: "@",
+    };
+  },
+
+  addCommands() {
+    return {
+      /**
+       * Insert a `CharacterMention` atom at the current trigger, replacing the
+       * `@query` text between the trigger and the cursor.
+       */
+      insertMention:
+        (id: string, label: string) =>
+        ({ editor }: { editor: Editor }) => {
+          const { state, schema } = editor;
+          const { from } = state.selection;
+          const atPos = findMentionTrigger(state.doc, from);
+          if (atPos < 0) return false;
+
+          const nodeType = schema.nodes[CHARACTER_MENTION];
+          if (!nodeType) return false;
+
+          const mention = nodeType.create({ id, label });
+          const tr = state.tr.deleteRange(atPos, from).insert(atPos, mention);
+          editor.view.dispatch(tr);
+          return true;
+        },
+    } as unknown as Partial<RawCommands>;
+  },
+});
+
+export default MentionAutocomplete;
diff --git a/packages/editor/src/nodes/MentionPicker.tsx b/packages/editor/src/nodes/MentionPicker.tsx
new file mode 100644
index 0000000..a4bf354
--- /dev/null
+++ b/packages/editor/src/nodes/MentionPicker.tsx
@@ -0,0 +1,182 @@
+/**
+ * MentionPicker — the React surface for the `@` autocomplete.
+ *
+ * It watches the editor for a live `@query` (via `editor.on("update")`), runs
+ * the injected `MentionProvider.search`, and renders a floating list positioned
+ * at the cursor. Arrow keys move the highlight, Enter/Click insert the mention,
+ * Escape closes. The actual insertion goes through the editor's `insertMention`
+ * command (see `mention.ts`).
+ *
+ * Render this once, next to `<EditorContent>`, passing the editor and a
+ * provider. The provider is supplied by the app so this package never touches
+ * the entity store directly.
+ */
+import { useEffect, useRef, useState } from "react";
+import type { Editor } from "@tiptap/core";
+import { mentionPickerState, findMentionTrigger, type MentionProvider } from "../mention.js";
+
+interface MentionPickerProps {
+  editor: Editor | null;
+  provider: MentionProvider | null;
+}
+
+interface Candidate {
+  id: string;
+  label: string;
+  subtitle?: string;
+}
+
+// The `insertMention` command is custom (not in TipTap's RawCommands), so we
+// reach it through a typed cast.
+type InsertMention = (id: string, label: string) => boolean;
+
+export function MentionPicker({ editor, provider }: MentionPickerProps) {
+  const [open, setOpen] = useState(false);
+  const [candidates, setCandidates] = useState<Candidate[]>([]);
+  const [selectedIndex, setSelectedIndex] = useState(0);
+  const [pos, setPos] = useState({ x: 0, y: 0 });
+  const listRef = useRef<HTMLUListElement>(null);
+
+  // Detect `@query` on every editor update and drive the picker state.
+  useEffect(() => {
+    if (!editor || !provider) return;
+
+    const onUpdate = () => {
+      const { from } = editor.state.selection;
+      const atPos = findMentionTrigger(editor.state.doc, from);
+      if (atPos < 0) {
+        setOpen(false);
+        mentionPickerState.open = false;
+        return;
+      }
+
+      const queryText = editor.state.doc.textBetween(atPos + 1, from) ?? "";
+      const coords = editor.view.coordsAtPos(from);
+      setPos({ x: coords.left, y: coords.bottom });
+      setOpen(true);
+      mentionPickerState.open = true;
+      mentionPickerState.query = queryText;
+      mentionPickerState.atPos = atPos;
+      mentionPickerState.from = from;
+      mentionPickerState.selectedIndex = 0;
+
+      const matches = provider.search(queryText);
+      setCandidates(matches);
+      setSelectedIndex(0);
+    };
+
+    editor.on("update", onUpdate);
+    return () => {
+      editor.off("update", onUpdate);
+    };
+  }, [editor, provider]);
+
+  // Auto-scroll the highlighted item into view.
+  useEffect(() => {
+    listRef.current?.children[selectedIndex]?.scrollIntoView({ block: "nearest" });
+  }, [selectedIndex]);
+
+  // Keep focus on the list so keyboard events are captured while open.
+  useEffect(() => {
+    if (open) listRef.current?.focus();
+  }, [open]);
+
+  const insert = (c: Candidate) => {
+    const cmd = (editor?.commands as unknown as { insertMention: InsertMention }).insertMention;
+    if (cmd) cmd(c.id, c.label);
+    setOpen(false);
+    mentionPickerState.open = false;
+  };
+
+  const onKeyDown = (e: React.KeyboardEvent) => {
+    e.stopPropagation();
+    if (e.key === "ArrowDown") {
+      e.preventDefault();
+      setSelectedIndex((i) => (i + 1) % Math.max(1, candidates.length));
+    } else if (e.key === "ArrowUp") {
+      e.preventDefault();
+      setSelectedIndex((i) => (i - 1 + candidates.length) % Math.max(1, candidates.length));
+    } else if (e.key === "Enter") {
+      e.preventDefault();
+      const sel = candidates[selectedIndex];
+      if (sel) insert(sel);
+    } else if (e.key === "Escape") {
+      e.preventDefault();
+      setOpen(false);
+      mentionPickerState.open = false;
+    }
+  };
+
+  if (!open || !provider) return null;
+
+  return (
+    <div
+      className="ps-mention-picker"
+      style={{
+        position: "fixed",
+        left: pos.x,
+        top: pos.y,
+        zIndex: 1000,
+        minWidth: 220,
+        maxWidth: 320,
+        maxHeight: 280,
+        overflowY: "auto",
+        boxSizing: "border-box",
+        background: "var(--ps-surface, #fff)",
+        color: "var(--ps-text, #1a1a1a)",
+        border: "1px solid var(--ps-border, #d8d8d8)",
+        borderRadius: 8,
+        boxShadow: "0 6px 20px rgba(0,0,0,0.15)",
+      }}
+      onKeyDown={onKeyDown}
+    >
+      <ul
+        ref={listRef}
+        tabIndex={-1}
+        style={{ listStyle: "none", margin: 0, padding: 4, outline: "none" }}
+      >
+        {candidates.length === 0 ? (
+          <li className="ps-mention-empty" style={{ padding: "10px 12px", color: "var(--ps-muted, #888)" }}>
+            No matches
+          </li>
+        ) : (
+          candidates.map((c, i) => (
+            <li
+              key={c.id}
+              className={`ps-mention-item${i === selectedIndex ? " is-selected" : ""}`}
+              onMouseDown={(e) => {
+                e.preventDefault();
+                insert(c);
+              }}
+              onMouseEnter={() => setSelectedIndex(i)}
+              style={{
+                padding: "8px 12px",
+                borderRadius: 6,
+                cursor: "pointer",
+                background: i === selectedIndex ? "var(--ps-accent, #0f3d3e)" : "transparent",
+                color: i === selectedIndex ? "#fff" : "inherit",
+              }}
+            >
+              <div style={{ fontWeight: 600 }}>{c.label}</div>
+              {c.subtitle && (
+                <div
+                  style={{
+                    fontSize: 12,
+                    opacity: i === selectedIndex ? 0.9 : 0.65,
+                    whiteSpace: "nowrap",
+                    overflow: "hidden",
+                    textOverflow: "ellipsis",
+                  }}
+                >
+                  {c.subtitle}
+                </div>
+              )}
+            </li>
+          ))
+        )}
+      </ul>
+    </div>
+  );
+}
+
+export default MentionPicker;
diff --git a/packages/editor/src/schema.ts b/packages/editor/src/schema.ts
index 20c8de9..80ef815 100644
--- a/packages/editor/src/schema.ts
+++ b/packages/editor/src/schema.ts
@@ -23,6 +23,7 @@ import SceneBreakNode from "./nodes/SceneBreak.js";
 import FootnoteInline from "./nodes/FootnoteInline.js";
 import FootnoteArea from "./nodes/FootnoteArea.js";
 import CharacterMention from "./nodes/CharacterMention.js";
+import { MentionAutocomplete } from "./mention.js";
 
 import {
   SCENE_BREAK,
@@ -49,6 +50,7 @@ export const pubScriptExtensions = [
   FootnoteInline,
   FootnoteArea,
   CharacterMention,
+  MentionAutocomplete,
 ];
 
 /**
diff --git a/packages/ui/src/AppShell.css b/packages/ui/src/AppShell.css
index cc775a9..d27a664 100644
--- a/packages/ui/src/AppShell.css
+++ b/packages/ui/src/AppShell.css
@@ -126,6 +126,115 @@ body {
   line-height: var(--ps-font-leading, 1.75);
 }
 
+/* ---- Writing surface: toolbar, focus/typewriter modes ---- */
+.ps-writing {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+}
+.ps-writing-toolbar {
+  display: flex;
+  align-items: center;
+  gap: 16px;
+  padding: 8px 16px;
+  border-bottom: 1px solid var(--ps-border);
+  background: var(--ps-surface);
+  flex: none;
+}
+.ps-chapter-select {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+.ps-chapter-select-label {
+  font-size: 11px;
+  text-transform: uppercase;
+  letter-spacing: 0.06em;
+  color: var(--ps-text-muted);
+}
+.ps-chapter-select select {
+  padding: 6px 10px;
+  border: 1px solid var(--ps-border);
+  border-radius: 8px;
+  background: var(--ps-canvas);
+  color: var(--ps-text);
+  font-size: 13px;
+  font-family: inherit;
+}
+.ps-toolbar-group {
+  display: flex;
+  gap: 4px;
+}
+.ps-tool {
+  padding: 5px 12px;
+  border: 1px solid transparent;
+  border-radius: 8px;
+  background: transparent;
+  color: var(--ps-text-muted);
+  font-size: 13px;
+  font-family: inherit;
+  cursor: pointer;
+}
+.ps-tool:hover {
+  color: var(--ps-text);
+  background: var(--ps-canvas);
+}
+.ps-tool.is-active {
+  color: var(--ps-text);
+  border-color: var(--ps-accent);
+  background: color-mix(in srgb, var(--ps-accent) 12%, transparent);
+}
+.ps-autosave-indicator {
+  margin-left: auto;
+  display: flex;
+  align-items: center;
+  gap: 7px;
+  font-size: 12px;
+  color: var(--ps-text-muted);
+}
+.ps-autosave-dot {
+  width: 7px;
+  height: 7px;
+  border-radius: 50%;
+  background: var(--ps-text-muted);
+}
+.ps-autosave-indicator[data-status="saving"] .ps-autosave-dot {
+  background: #d9a441;
+}
+.ps-autosave-indicator[data-status="dirty"] .ps-autosave-dot {
+  background: #d96c4b;
+}
+.ps-autosave-indicator[data-status="saved"] .ps-autosave-dot {
+  background: #4f9d69;
+}
+
+/* Focus mode: dim the whole document, then restore the block under the cursor. */
+.ps-editor-focus .ps-editor-content {
+  opacity: 0.22;
+  transition: opacity 0.15s ease;
+}
+.ps-editor-focus .ps-editor-content .ps-focus-active,
+.ps-editor-focus .ps-editor-content .ps-focus-active * {
+  opacity: 1;
+  transition: opacity 0.05s ease;
+}
+
+.ps-writing-status {
+  display: flex;
+  gap: 16px;
+  align-items: center;
+  padding: 6px 16px;
+  border-top: 1px solid var(--ps-border);
+  background: var(--ps-surface);
+  color: var(--ps-text-muted);
+  font-size: 12px;
+  flex: none;
+}
+.ps-writing-status-note {
+  margin-left: auto;
+  color: var(--ps-text);
+}
+
 /* ---- Sidebar nav ---- */
 .ps-logo {
   font-weight: 700;
diff --git a/server/src/index.ts b/server/src/index.ts
index a37e253..5a15ce1 100644
--- a/server/src/index.ts
+++ b/server/src/index.ts
@@ -1,3 +1,4 @@
+import { fileURLToPath } from "node:url";
 import Fastify from "fastify";
 import cors from "@fastify/cors";
 import cookie from "@fastify/cookie";
@@ -74,7 +75,16 @@ export async function start() {
   return app;
 }
 
-start().catch((err) => {
-  console.error("Failed to start server:", err);
-  process.exit(1);
-});
+// Auto-boot only when this file is the CLI entry point (pnpm dev / start),
+// not when imported by tests (vitest) — otherwise start() would try to bind
+// the port and tear the test process down.
+const invokedDirectly =
+  process.argv[1] !== undefined &&
+  fileURLToPath(import.meta.url) === process.argv[1];
+
+if (invokedDirectly) {
+  start().catch((err) => {
+    console.error("Failed to start server:", err);
+    process.exit(1);
+  });
+}
diff --git a/server/src/mapping.ts b/server/src/mapping.ts
index 8018f19..9eef45e 100644
--- a/server/src/mapping.ts
+++ b/server/src/mapping.ts
@@ -183,7 +183,7 @@ export function toEntity(r: EntityRow): Entity {
       bio: f.bio ?? "",
       appearance: f.appearance ?? "",
       voice: f.voice ?? "",
-      relationships: f.relationships ?? "",
+      relationships: typeof f.relationships === "string" ? JSON.parse(f.relationships) : (f.relationships ?? []),
       arc: f.arc ?? "",
       status: f.status ?? "active",
       tags: f.tags ?? [],
@@ -251,6 +251,21 @@ export function entityToRow(e: Entity): Omit<EntityRow, "created_at" | "updated_
 }
 
 // ---- helpers ----
+/** Concatenate every human-readable field of an entity into one searchable string. */
+export function entitySearchText(e: Entity): string {
+  if ("fields" in e) {
+    const parts = [e.name, e.kind];
+    for (const v of Object.values(e.fields)) if (typeof v === "string") parts.push(v);
+    return parts.join(" ");
+  }
+  if ("body" in e) {
+    return [e.body, ...e.tags].join(" ");
+  }
+  const c = e as Character;
+  const relText = (c.relationships ?? []).map((r) => `${r.targetId} ${r.kind} ${r.note}`).join(" ");
+  return [c.name, c.role, c.bio, c.appearance, c.voice, relText, c.arc, c.status, ...c.tags].join(" ");
+}
+
 /** Count words in a ProseMirror doc (text nodes only). */
 export function wordCount(doc: unknown): number {
   let count = 0;
diff --git a/server/src/routes.ts b/server/src/routes.ts
index 997dae7..99721cd 100644
--- a/server/src/routes.ts
+++ b/server/src/routes.ts
@@ -15,6 +15,7 @@ import {
   toAISession,
   toEntity,
   entityToRow,
+  entitySearchText,
   wordCount,
   type ProjectRow,
   type ShareRow,
@@ -58,7 +59,7 @@ const entityCreate = z.object({
   bio: z.string().optional(),
   appearance: z.string().optional(),
   voice: z.string().optional(),
-  relationships: z.string().optional(),
+  relationships: z.array(z.any()).optional(),
   arc: z.string().optional(),
   status: z.enum(["active", "archived"]).optional(),
   tags: z.array(z.string()).optional(),
@@ -315,7 +316,7 @@ export function registerRoutes(app: FastifyInstance): void {
   // ---------- Entities (characters / world / notes) ----------
   app.get("/api/projects/:id/entities", async (req) => {
     const { id } = req.params as { id: string };
-    const { kind } = req.query as { kind?: string };
+    const { kind, q } = req.query as { kind?: string; q?: string };
     requireProjectAccess(app, req, id);
     let rows: EntityRow[];
     if (kind) {
@@ -323,7 +324,12 @@ export function registerRoutes(app: FastifyInstance): void {
     } else {
       rows = db.prepare("SELECT * FROM entities WHERE project_id = ?").all(id) as EntityRow[];
     }
-    return { entities: rows.map(toEntity) };
+    let entities = rows.map(toEntity);
+    if (q) {
+      const needle = q.toLowerCase();
+      entities = entities.filter((e) => entitySearchText(e).toLowerCase().includes(needle));
+    }
+    return { entities };
   });
 
   app.post("/api/projects/:id/entities", async (req) => {
@@ -337,7 +343,7 @@ export function registerRoutes(app: FastifyInstance): void {
     if (body.kind === "character") {
       entity = {
         id: eid, projectId: id, name: body.name ?? "", role: body.role ?? "", bio: body.bio ?? "",
-        appearance: body.appearance ?? "", voice: body.voice ?? "", relationships: body.relationships ?? "",
+        appearance: body.appearance ?? "", voice: body.voice ?? "", relationships: body.relationships ?? [],
         arc: body.arc ?? "", status: body.status ?? "active", tags: body.tags ?? [],
       };
     } else if (body.kind === "world") {
@@ -374,7 +380,7 @@ export function registerRoutes(app: FastifyInstance): void {
     if (kind === "character") {
       entity = {
         id, projectId, name: body.name ?? existing.name, role: body.role ?? "", bio: body.bio ?? "",
-        appearance: body.appearance ?? "", voice: body.voice ?? "", relationships: body.relationships ?? "",
+        appearance: body.appearance ?? "", voice: body.voice ?? "", relationships: body.relationships ?? [],
         arc: body.arc ?? "", status: body.status ?? "active", tags: body.tags ?? [],
       };
     } else if (kind === "world") {