diff --git a/bun.lock b/bun.lock
index b2b0ca63c0..697a5f29c5 100644
--- a/bun.lock
+++ b/bun.lock
@@ -38,7 +38,7 @@
     },
     "packages/rt-client": {
       "name": "@mattstack/rt-client",
-      "version": "0.30.0",
+      "version": "0.31.0",
       "dependencies": {
         "jsonc-parser": "^3.3.1",
       },
diff --git a/packages/rt-client/package.json b/packages/rt-client/package.json
index 21c4cac6af..5181a7324d 100644
--- a/packages/rt-client/package.json
+++ b/packages/rt-client/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@mattstack/rt-client",
-  "version": "0.30.0",
+  "version": "0.31.0",
   "type": "module",
   "exports": {
     ".": {
diff --git a/packages/rt-client/src/settings/__tests__/write.test.ts b/packages/rt-client/src/settings/__tests__/write.test.ts
index e9cc670917..11f3fe8c7c 100644
--- a/packages/rt-client/src/settings/__tests__/write.test.ts
+++ b/packages/rt-client/src/settings/__tests__/write.test.ts
@@ -521,6 +521,19 @@ describe("settings/unset", () => {
     expect(() => unsetSetting("rt.doesNotExist", "user")).toThrow(/unknown setting/);
   });
 
+  test("removes a retired key a store still carries, from any scope", () => {
+    mkdirSync(dirname(machineSettingsPath()), { recursive: true });
+    writeFileSync(machineSettingsPath(), `{\n  "mattstack.mode": "dev",\n  "mattstack.appPath": "/Applications/mattstack-dev.app"\n}\n`);
+    expect(unsetSetting("mattstack.mode", "machine")).toBe(true);
+    const after = readFileSync(machineSettingsPath(), "utf8");
+    expect(after).not.toContain("mattstack.mode");
+    expect(after).toContain("mattstack.appPath");
+  });
+
+  test("refuses a retired key with a repo identity", () => {
+    expect(() => unsetSetting("mattstack.mode", "user", { repoIdentity: IDENTITY })).toThrow(/not repo-scoped/);
+  });
+
   test("refuses a scope the def does not allow", () => {
     expect(() => unsetSetting("rt.repoIdentityOverrides", "user")).toThrow(/cannot be unset in the user store/);
   });
diff --git a/packages/rt-client/src/settings/write.ts b/packages/rt-client/src/settings/write.ts
index 48cb5f449e..7fe753a515 100644
--- a/packages/rt-client/src/settings/write.ts
+++ b/packages/rt-client/src/settings/write.ts
@@ -98,7 +98,7 @@ import { applyEdits, modify, parseTree, type JSONPath, type Node, type ParseErro
 import { randomBytes } from "crypto";
 import { dirname } from "path";
 import { machineSettingsPath, teamSettingsPath, userSettingsPath } from "./paths.ts";
-import { getDef, isMigrated, validateValue, type SettingDef, type SettingScope } from "./registry-machinery.ts";
+import { getDef, isMigrated, isRetiredKey, validateValue, type SettingDef, type SettingScope } from "./registry-machinery.ts";
 import { listTeams } from "./stores.ts";
 import { isJoinedTeam } from "./team-local-read.ts";
 
@@ -171,9 +171,15 @@ export function setSetting(key: string, value: unknown, scope: SettingScope, opt
  * with no local store included — nothing to remove is success, not an error),
  * and a key not present in the store is a no-op. Returns whether anything was
  * actually removed; the local-only reminder prints only on a real removal.
+ * A retired key is not in the registry but may linger in a store, so it can
+ * still be removed from any scope.
  */
 export function unsetSetting(key: string, scope: SettingScope, opts: SetSettingOpts = {}): boolean {
   const def = getDef(key);
+  if (!def && isRetiredKey(key)) {
+    if (opts.repoIdentity !== undefined) refuse(`"${key}" is not repo-scoped; omit the repo identity`);
+    return removeKeyFromScope(key, scope, opts, [key]);
+  }
   if (!def) {
     refuse(`unknown setting "${key}" — not in the settings registry (see \`rt settings list\`)`);
   }
@@ -190,10 +196,14 @@ export function unsetSetting(key: string, scope: SettingScope, opts: SetSettingO
     refuse(`"${key}" is not repo-scoped — omit the repo identity`);
   }
 
+  const jsonPath: JSONPath = opts.repoIdentity !== undefined ? ["repos", opts.repoIdentity, key] : [key];
+  return removeKeyFromScope(key, scope, opts, jsonPath);
+}
+
+function removeKeyFromScope(key: string, scope: SettingScope, opts: SetSettingOpts, jsonPath: JSONPath): boolean {
   const storePath = resolveStorePathForUnset(scope, opts);
   if (storePath === null || !existsSync(storePath)) return false;
 
-  const jsonPath: JSONPath = opts.repoIdentity !== undefined ? ["repos", opts.repoIdentity, key] : [key];
   const removed = removeFromStore(storePath, jsonPath);
 
   if (removed) {