fix(host): say what's wrong with a backup or restore path, and let restore take --name

.lane/memory/apps/host/src/backup.ts/01M4ZYZJRBTSD6WJVT8HEH8XQ0-a-restored-copy-always-gets.md

@@ -3,10 +3,10 @@ id: 01M4ZYZJRBTSD6WJVT8HEH8XQ0
 anchor: function restore
 created: 2026-10-15T14:20:42Z
 norm: '1'
-sig: 05c78f711a9a9228
-body_hash: dac1c9f5bf404d33
-raw_hash: 3f94de7e3f41e61b
-vouched: 2026-10-22T21:13:56Z
+sig: 34ffa326bc970eeb
+body_hash: b7adc8d1cb030bd6
+raw_hash: 9cd4b31a0f2d0251
+vouched: 2026-10-22T22:15:45Z
 lines: 119-158
 ---
 

.lane/memory/apps/host/src/backup.ts/01M5J2ZT89CTF4ECFNG6YN408R-a-restored-store-s-metadatad.md

@@ -3,10 +3,10 @@ id: 01M5J2ZT89CTF4ECFNG6YN408R
 anchor: function restore
 created: 2026-10-22T15:17:03Z
 norm: '1'
-sig: 05c78f711a9a9228
-body_hash: dac1c9f5bf404d33
-raw_hash: 3f94de7e3f41e61b
-vouched: 2026-10-22T21:13:56Z
+sig: 34ffa326bc970eeb
+body_hash: b7adc8d1cb030bd6
+raw_hash: 9cd4b31a0f2d0251
+vouched: 2026-10-22T22:15:45Z
 lines: 119-164
 ---
 

.lane/memory/apps/host/src/backup.ts/01M5JQD5HXE7X0AR39PYQVNYXR-a-copy-restored-into-another.md

@@ -3,9 +3,10 @@ id: 01M5JQD5HXE7X0AR39PYQVNYXR
 anchor: function restore
 created: 2026-10-22T21:13:52Z
 norm: '1'
-sig: 05c78f711a9a9228
-body_hash: dac1c9f5bf404d33
-raw_hash: 3f94de7e3f41e61b
+sig: 34ffa326bc970eeb
+body_hash: b7adc8d1cb030bd6
+raw_hash: 9cd4b31a0f2d0251
+vouched: 2026-10-22T22:15:45Z
 lines: 120-166
 ---
 

.lane/memory/apps/host/src/cli.ts/01M4YY5SXJFQK8VXT78X1E0KAE-every-command-but-serve-must.md

@@ -4,9 +4,9 @@ anchor: function main
 created: 2026-10-15T04:47:23Z
 norm: '1'
 sig: 7d5d3f63a3bddde4
-body_hash: 400f5a75900a8a04
-raw_hash: 5b856ae56acd38c6
-vouched: 2026-10-22T21:30:38Z
+body_hash: f49f2a7319f14703
+raw_hash: 8fcaafdae8a2bc74
+vouched: 2026-10-22T22:15:45Z
 lines: 253-482
 ---
 

.lane/memory/apps/host/src/cli.ts/01M5J0BZWP8SCBK522YT2HMZDZ-ace-info-prints-agent-access.md

@@ -4,9 +4,9 @@ anchor: function main
 created: 2026-10-22T14:31:16Z
 norm: '1'
 sig: 7d5d3f63a3bddde4
-body_hash: 400f5a75900a8a04
-raw_hash: 5b856ae56acd38c6
-vouched: 2026-10-22T21:30:38Z
+body_hash: f49f2a7319f14703
+raw_hash: 8fcaafdae8a2bc74
+vouched: 2026-10-22T22:15:45Z
 lines: 332-614
 ---
 

apps/host/src/backup.ts

@@ -9,7 +9,7 @@ import {
 	rmSync,
 	writeFileSync,
 } from "node:fs";
-import { join, resolve } from "node:path";
+import { dirname, join, resolve } from "node:path";
 import { DatabaseSync } from "node:sqlite";
 
 import { openNodeSqliteDatabase } from "@earendil-works/pi-durable/storage/sqlite/node";
@@ -79,7 +79,18 @@ export async function backup(record: catalog.Listing, directory: string): Promis
 	const hosted = record.hosted ? await exported(record) : undefined;
 	const path = resolve(directory);
 	// An existing destination must never be overwritten or removed by failed-backup cleanup.
-	mkdirSync(path, { mode: 0o700 });
+	try {
+		mkdirSync(path, { mode: 0o700 });
+	} catch (error) {
+		const { code } = error as NodeJS.ErrnoException;
+		if (code === "EEXIST") {
+			throw new Error(`${path} already exists. Back up into a new directory.`, { cause: error });
+		}
+		if (code === "ENOENT") {
+			throw new Error(`${dirname(path)} doesn't exist. Create it first.`, { cause: error });
+		}
+		throw error;
+	}
 	try {
 		const source = catalog.paths(record.id);
 		save(join(path, "channel.json"), record);
@@ -117,23 +128,38 @@ export async function backup(record: catalog.Listing, directory: string): Promis
  * A backup as a new local channel. The new ID and lane prefix keep it from ever running as the
  * original, which may still be live here or on its hosting service.
  */
-export async function restore(directory: string, dir?: string): Promise<catalog.Listing> {
+export async function restore(
+	directory: string,
+	options: { dir?: string; name?: string } = {},
+): Promise<catalog.Listing> {
 	const path = resolve(directory);
+	if (!existsSync(path)) throw new Error(`${path} doesn't exist.`);
+	if (!existsSync(join(path, "backup.json"))) {
+		throw new Error(`${path} isn't an Ace backup: it has no backup.json.`);
+	}
 	const manifest = JSON.parse(readFileSync(join(path, "backup.json"), "utf8")) as {
 		format: number;
 		files: { path: string; sha256: string }[];
 	};
 	if (manifest.format !== 1) throw new Error(`Unsupported backup format ${manifest.format}`);
 	for (const file of manifest.files) {
+		if (!existsSync(join(path, file.path))) {
+			throw new Error(`The backup is incomplete: ${file.path} is missing from ${path}.`);
+		}
 		if (await checksum(join(path, file.path)) !== file.sha256) {
 			throw new Error(`${file.path} does not match its checksum in backup.json`);
 		}
 	}
 	const original = JSON.parse(readFileSync(join(path, "channel.json"), "utf8")) as catalog.Listing;
+	const draft = catalog.draft(
+		await project(options.dir || original.project),
+		original.model,
+		options.name,
+	);
 	const record: catalog.Listing = {
-		...catalog.draft(await project(dir || original.project), original.model),
-		name: catalog.restored(original.name),
-		named: original.named !== false,
+		...draft,
+		name: options.name ? draft.name : catalog.restored(original.name),
+		named: !!options.name || original.named !== false,
 		summary: original.summary,
 	};
 	const { base, storage } = catalog.paths(record.id);

apps/host/src/cli.ts

@@ -60,7 +60,8 @@ const USAGE = `ace — channels on this host
   ace tabs [--port <port>] [--json]              list open windows and their current channel's tabs
   ace tab rename <window> <channel> <tab> <name>  rename one tab; an empty name restores its default
   ace backup <channel> <directory>              snapshot a local or hosted channel's data into a new directory
-  ace restore <directory> [--project <dir>]      restore a backup as a new local channel
+  ace restore <directory> [--project <dir>] [--name <name>]
+                                                restore a backup as a new local channel
   ace export <channel> <file>                    save a channel's chats as an editable seed file
   ace import <file> [--project <dir>] [--name <name>] [--now]
                                                 add a seed as a new local channel; --now moves its
@@ -478,9 +479,9 @@ async function main() {
 		}
 		case "restore": {
 			if (positionals.length !== 2) {
-				throw new Error("ace restore <backup-directory> [--project <dir>]");
+				throw new Error("ace restore <backup-directory> [--project <dir>] [--name <name>]");
 			}
-			const record = await restore(ref!, flags.project);
+			const record = await restore(ref!, { dir: flags.project, name: flags.name });
 			return console.log(`${record.name}\t${record.id}`);
 		}
 		case "import": {

apps/host/src/manage.ts

@@ -40,6 +40,7 @@ export async function defaultModel(): Promise<ModelRef> {
 /** The Git top level containing `dir`, which needs a commit for lanes to start from. */
 export async function project(dir: string): Promise<string> {
 	dir = resolve(dir === "~" ? homedir() : dir.startsWith("~/") ? homedir() + dir.slice(1) : dir);
+	if (!existsSync(dir)) throw new Error(`${dir} doesn't exist.`);
 	const result = await git(dir, ["rev-parse", "--show-toplevel"]);
 	if (result.status === null) throw new Error("Git is unavailable. Check Settings → Ace Helper.");
 	if (result.status !== 0) {

docs/data.md

@@ -76,12 +76,12 @@ keeps the original working-directory paths; it is not a way to move lanes to ano
 
 ## Restore as a new channel
 
-`ace restore <backup-directory> [--project <dir>]` verifies every file against `backup.json`, then
-adds the backup as a new local channel on this host, in the recorded project or `--project`. A
-hosted snapshot is imported and checked against its digest; a local `channel.sqlite` is copied. The
-copy has a new ID and a new lane branch prefix, so it can never run as the original channel, which
-may still be live here or on its service. Its pi metadata keeps the original name, so refer to it by
-ID while both exist. The backup itself is left unchanged, and a failed restore removes only the new
+`ace restore <backup-directory> [--project <dir>] [--name <name>]` verifies every file against
+`backup.json`, then adds the backup as a new local channel on this host, in the recorded project or
+`--project`. A hosted snapshot is imported and checked against its digest; a local `channel.sqlite`
+is copied. The copy has a new ID and a new lane branch prefix, so it can never run as the original
+channel, which may still be live here or on its service. It takes `--name`, or the original's name
+with `-1`, `-2`, … added while that name is taken. The backup itself is left unchanged, and a failed restore removes only the new
 channel's directory.
 
 The restored chats keep the original working-directory and lane paths. If the backup was taken