diff --git a/web/src/api.ts b/web/src/api.ts
index 89cec3f..b1cd03d 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -9,6 +9,7 @@ import type {
   NameBatch,
   Projects,
   RecentDirs,
+  RetainedWorktree,
   Session,
   Uuid,
 } from "./types.js";
@@ -97,4 +98,22 @@ export async function fetchBranches(path: string): Promise<Branches> {
   return jsonOrError(await fetch(url, { credentials: "same-origin" }));
 }
 
+/** The daemon's retained worktrees (#80): trees kept after a session ended
+ * with unsaved work, with what is currently in the way. Drives the
+ * retained-worktrees view (#84). */
+export async function listWorktrees(): Promise<RetainedWorktree[]> {
+  return jsonOrError(await fetch(routes.WORKTREES, { credentials: "same-origin" }));
+}
+
+/** Reclaim a retained worktree: removes its directory and drops the store
+ * entry. Never deletes the branch (docs/WORKTREES.md). */
+export async function reclaimWorktree(id: Uuid): Promise<void> {
+  await jsonOrError(
+    await fetch(routes.worktree(id), {
+      method: "DELETE",
+      credentials: "same-origin",
+    }),
+  );
+}
+
 export { eventsWsUrl } from "./routes.js";
diff --git a/web/src/routes.ts b/web/src/routes.ts
index 812160a..299812c 100644
--- a/web/src/routes.ts
+++ b/web/src/routes.ts
@@ -13,6 +13,7 @@ export const PROJECTS = "/api/projects";
 export const GITROOT = "/api/gitroot";
 export const NAMES = "/api/names";
 export const BRANCHES = "/api/branches";
+export const WORKTREES = "/api/worktrees";
 export const EVENTS = "/api/events";
 
 /** Name of the query parameter `DIRS` and `GITROOT` both take. */
@@ -29,6 +30,11 @@ export function attach(id: Uuid): string {
   return `${API_PREFIX}/attach/${encodeURIComponent(id)}`;
 }
 
+/** `DELETE /api/worktrees/:id` — reclaim one retained worktree (#80). */
+export function worktree(id: Uuid): string {
+  return `${WORKTREES}/${encodeURIComponent(id)}`;
+}
+
 /** Append the `path` query parameter `DIRS` and `GITROOT` accept. */
 export function withPathQuery(route: string, value: string): string {
   return `${route}?${PATH_QUERY}=${encodeURIComponent(value)}`;
diff --git a/web/src/types.ts b/web/src/types.ts
index 11991c3..10a8e43 100644
--- a/web/src/types.ts
+++ b/web/src/types.ts
@@ -133,6 +133,54 @@ export interface BranchInfo {
 /** `GET /api/branches?path=` — the local branches of one repository (#55). */
 export type Branches = BranchInfo[];
 
+/** Why a retained worktree outlived its session (#80). New values are
+ * additive; unknown reasons render generically. */
+export type RetainedReason = "force-killed" | "exited-with-unsaved-work";
+
+/** What currently blocks an unforced kill of a worktree's session (#80),
+ * recomputed by the daemon on every read. All counts default to 0 on the
+ * wire for older daemons. */
+export interface InTheWay {
+  uncommitted_files?: number;
+  untracked_files?: number;
+  unpushed_commits?: number;
+}
+
+/** One entry of `GET /api/worktrees` (#80): a retained worktree with its
+ * in-the-way state as of this read. Reclaiming it removes the directory but
+ * never the branch. Mirrors `maestro_protocol::RetainedWorktree`. */
+export interface RetainedWorktree {
+  id: Uuid;
+  path: string;
+  base_repo: string;
+  branch: string;
+  reason: RetainedReason;
+  retained_at: IsoTimestamp;
+  in_the_way?: InTheWay;
+}
+
+/** The phrasing `maestro_protocol::InTheWay`'s Display impl uses — shared by
+ * the kill refusal, the TUI and this client, so no two clients can describe
+ * the same tree differently. Zero parts are omitted; all-zero renders
+ * "no unsaved work". */
+export function formatInTheWay(w: InTheWay): string {
+  const parts: string[] = [];
+  const push = (n: number | undefined, unit: string): void => {
+    if (!n || n <= 0) return;
+    parts.push(n === 1 ? `1 ${unit}` : `${n} ${unit}s`);
+  };
+  push(w.uncommitted_files, "uncommitted file");
+  push(w.untracked_files, "untracked file");
+  push(w.unpushed_commits, "unpushed commit");
+  return parts.length > 0 ? parts.join(", ") : "no unsaved work";
+}
+
+/** Same reason labels the CLI table and the TUI overlay use; unknown future
+ * reasons render their raw wire value. */
+export function reasonLabel(reason: RetainedReason): string {
+  return reason;
+}
+
 export interface CreateSessionRequest {
   cwd: string;
   command: string;