fix(launcher): address code review findings in stats sync

- merge-catalog: stop dropping anilist_id on every new anime insert
  (bun:sqlite .get() returns null, so the old !== undefined guard always
  fired); the guard was dead anyway since a colliding id is caught earlier
- sync-command: throw instead of fail() inside runHostSync so the finally
  block runs and temp dirs holding snapshot data are cleaned up on failure
- ssh: shell-quote the user-supplied --remote-cmd in the probe, and reject
  option-like (-prefixed) SSH hosts that ssh/scp would parse as flags
- sync-db: close the remote handle if opening the local DB throws
- sync-shared: treat EPERM from process.kill(pid, 0) as alive, not dead
- cli-parser: trim the sync host before the mode-exclusivity check
- tests: cover anilist_id preservation, anilist-based anime matching, and
  the SSH host/shell-quote guards

launcher/commands/sync-command.ts

@@ -9,7 +9,13 @@ import {
   formatMergeSummary,
   mergeSnapshotIntoDb,
 } from '../sync/sync-db.js';
-import { resolveRemoteSubminerCommand, runScp, runSsh, shellQuote } from '../sync/ssh.js';
+import {
+  assertSafeSshHost,
+  resolveRemoteSubminerCommand,
+  runScp,
+  runSsh,
+  shellQuote,
+} from '../sync/ssh.js';
 import { resolvePathMaybe } from '../util.js';
 import type { LauncherCommandContext } from './context.js';
 
@@ -66,6 +72,7 @@ function cleanupRemote(host: string, remoteTmpDir: string): void {
 function runHostSync(context: LauncherCommandContext, dbPath: string): void {
   const { args } = context;
   const host = args.syncHost;
+  assertSafeSshHost(host);
 
   ensureTrackerQuiescent(context, dbPath);
 
@@ -75,10 +82,13 @@ function runHostSync(context: LauncherCommandContext, dbPath: string): void {
   const localTmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-sync-'));
   let remoteTmpDir = '';
   try {
+    // Signal failures by throwing (not fail(), which exits synchronously and
+    // would skip the finally cleanup, leaking temp dirs holding snapshot data).
+    // main().catch() reports the message the same way fail() would.
     const mktemp = runSsh(host, 'mktemp -d /tmp/subminer-sync.XXXXXX');
     remoteTmpDir = mktemp.stdout.trim();
     if (mktemp.status !== 0 || !remoteTmpDir.startsWith('/tmp/')) {
-      fail(`Could not create a temporary directory on ${host}.`);
+      throw new Error(`Could not create a temporary directory on ${host}.`);
     }
 
     const forceFlag = args.syncForce ? ' --force' : '';
@@ -94,7 +104,7 @@ function runHostSync(context: LauncherCommandContext, dbPath: string): void {
       `${remoteCmd} sync --snapshot ${shellQuote(remoteSnapshot)}${forceFlag}`,
     );
     if (snapshotRun.status !== 0) {
-      fail(`Remote snapshot failed on ${host}.`);
+      throw new Error(`Remote snapshot failed on ${host}.`);
     }
 
     const pulledSnapshot = path.join(localTmpDir, 'remote.sqlite');
@@ -113,7 +123,7 @@ function runHostSync(context: LauncherCommandContext, dbPath: string): void {
     );
     process.stdout.write(mergeRun.stdout);
     if (mergeRun.status !== 0) {
-      fail(
+      throw new Error(
         `Remote merge failed on ${host}. The local database was updated; re-run "subminer sync ${host}" once the remote issue is fixed.`,
       );
     }

launcher/config/cli-parser-builder.ts

@@ -316,7 +316,8 @@ export function parseCliPrograms(
     .option('--remote-cmd <cmd>', 'subminer command to run on the remote host')
     .option('-f, --force', 'Skip the running-app safety check')
     .option('--log-level <level>', 'Log level')
-    .action((host: string | undefined, options: Record<string, unknown>) => {
+    .action((rawHost: string | undefined, options: Record<string, unknown>) => {
+      const host = typeof rawHost === 'string' ? rawHost.trim() : '';
       const snapshot = typeof options.snapshot === 'string' ? options.snapshot.trim() : '';
       const merge = typeof options.merge === 'string' ? options.merge.trim() : '';
       const modes = [Boolean(host), Boolean(snapshot), Boolean(merge)].filter(Boolean).length;
@@ -327,7 +328,7 @@ export function parseCliPrograms(
         throw new Error('Sync host, --snapshot, and --merge cannot be combined.');
       }
       syncTriggered = true;
-      syncHost = host?.trim() || null;
+      syncHost = host || null;
       syncSnapshotPath = snapshot || null;
       syncMergePath = merge || null;
       syncRemoteCmd = typeof options.remoteCmd === 'string' ? options.remoteCmd.trim() || null : null;

launcher/sync/merge-catalog.ts

@@ -138,15 +138,9 @@ export function mergeAnime(
       );
       continue;
     }
-    // anilist_id is UNIQUE; drop it if another local row (matched by a
+    // No local row matched by anilist_id (checked first in `existing` above)
-    // different title key) already claims it.
+    // or title key, so the remote anilist_id — if any — is free to insert as-is.
-    const anilistTaken =
+    const values = ANIME_COPY_COLUMNS.map((column) => row[column]);
-      row.anilist_id !== null && byAnilist.get(row.anilist_id) !== undefined
-        ? null
-        : row.anilist_id;
-    const values = ANIME_COPY_COLUMNS.map((column) =>
-      column === 'anilist_id' ? anilistTaken : row[column],
-    );
     map.set(remoteId, insertRow(local, 'imm_anime', ANIME_COPY_COLUMNS, values));
     summary.animeAdded += 1;
   }

launcher/sync/ssh.test.ts

@@ -0,0 +1,19 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { assertSafeSshHost, shellQuote } from './ssh.js';
+
+test('assertSafeSshHost rejects option-like hosts', () => {
+  assert.throws(() => assertSafeSshHost('-oProxyCommand=touch pwned'), /looks like an option/);
+  assert.throws(() => assertSafeSshHost('-lroot'), /looks like an option/);
+});
+
+test('assertSafeSshHost accepts normal destinations', () => {
+  assert.doesNotThrow(() => assertSafeSshHost('macbook'));
+  assert.doesNotThrow(() => assertSafeSshHost('user@192.168.1.20'));
+  assert.doesNotThrow(() => assertSafeSshHost('ssh-alias'));
+});
+
+test('shellQuote escapes single quotes and wraps in quotes', () => {
+  assert.equal(shellQuote('subminer'), `'subminer'`);
+  assert.equal(shellQuote(`a'; rm -rf ~; '`), `'a'\\''; rm -rf ~; '\\'''`);
+});

launcher/sync/ssh.ts

@@ -5,12 +5,24 @@ export interface RemoteRunResult {
   stdout: string;
 }
 
+/**
+ * ssh/scp have no `--` terminator for the destination, so a host that starts
+ * with `-` (e.g. `-oProxyCommand=...`) is parsed as an option. Reject those
+ * before spawning.
+ */
+export function assertSafeSshHost(host: string): void {
+  if (host.startsWith('-')) {
+    throw new Error(`Refusing to use SSH host that looks like an option: ${host}`);
+  }
+}
+
 /**
  * Run a command on the SSH host. stdin/stderr stay attached to the terminal
  * so key passphrase / password prompts and remote progress output work;
  * stdout is captured for the caller.
  */
 export function runSsh(host: string, remoteCommand: string): RemoteRunResult {
+  assertSafeSshHost(host);
   const result = spawnSync('ssh', [host, remoteCommand], {
     encoding: 'utf8',
     stdio: ['inherit', 'pipe', 'inherit'],
@@ -43,11 +55,18 @@ export function shellQuote(value: string): string {
  * configured command first and fall back to the default install location.
  */
 export function resolveRemoteSubminerCommand(host: string, preferred: string | null): string {
-  const candidates = preferred ? [preferred] : ['subminer', '~/.local/bin/subminer'];
+  // Trusted defaults stay unquoted so the remote shell expands `~`; the
+  // user-supplied override is shell-quoted to prevent command injection.
+  const candidates: Array<{ value: string; probe: string }> = preferred
+    ? [{ value: preferred, probe: shellQuote(preferred) }]
+    : [
+        { value: 'subminer', probe: 'subminer' },
+        { value: '~/.local/bin/subminer', probe: '~/.local/bin/subminer' },
+      ];
   for (const candidate of candidates) {
-    const probe = runSsh(host, `command -v ${candidate} >/dev/null 2>&1`);
+    const probe = runSsh(host, `command -v ${candidate.probe} >/dev/null 2>&1`);
     if (probe.status === 0) {
-      return candidate;
+      return candidate.value;
     }
   }
   throw new Error(

launcher/sync/sync-db.test.ts

@@ -151,6 +151,65 @@ test('is idempotent: re-merging the same snapshot changes nothing', () => {
   }
 });
 
+test('preserves anilist_id when inserting a new anime from the snapshot', () => {
+  const { dir, localPath, remotePath } = makeDbPair();
+  try {
+    insertFixtureSession(remotePath, {
+      uuid: 'remote-1',
+      videoKey: 'showb-e1',
+      animeTitleKey: 'showb',
+      startedAtMs: BASE_MS,
+      applyLifetime: true,
+    });
+    const remoteDb = new Database(remotePath, { readwrite: true });
+    remoteDb.prepare(`UPDATE imm_anime SET anilist_id = 12345 WHERE normalized_title_key = 'showb'`).run();
+    remoteDb.close();
+
+    const summary = mergeSnapshotIntoDb(localPath, remotePath);
+    assert.equal(summary.animeAdded, 1);
+    const anime = queryOne<{ anilist_id: number }>(
+      localPath,
+      `SELECT anilist_id FROM imm_anime WHERE normalized_title_key = 'showb'`,
+    );
+    assert.equal(anime?.anilist_id, 12345);
+  } finally {
+    fs.rmSync(dir, { recursive: true, force: true });
+  }
+});
+
+test('matches an existing local anime by anilist_id even when the title key differs', () => {
+  const { dir, localPath, remotePath } = makeDbPair();
+  try {
+    insertFixtureSession(localPath, {
+      uuid: 'local-1',
+      videoKey: 'showa-e1',
+      animeTitleKey: 'show-romaji',
+      startedAtMs: BASE_MS,
+      applyLifetime: true,
+    });
+    insertFixtureSession(remotePath, {
+      uuid: 'remote-1',
+      videoKey: 'showa-e2',
+      animeTitleKey: 'show-native',
+      startedAtMs: BASE_MS + DAY_MS,
+      applyLifetime: true,
+    });
+    const localDb = new Database(localPath, { readwrite: true });
+    localDb.prepare(`UPDATE imm_anime SET anilist_id = 999 WHERE normalized_title_key = 'show-romaji'`).run();
+    localDb.close();
+    const remoteDb = new Database(remotePath, { readwrite: true });
+    remoteDb.prepare(`UPDATE imm_anime SET anilist_id = 999 WHERE normalized_title_key = 'show-native'`).run();
+    remoteDb.close();
+
+    const summary = mergeSnapshotIntoDb(localPath, remotePath);
+    // Same anilist_id → one anime, not two.
+    assert.equal(summary.animeAdded, 0);
+    assert.equal(count(localPath, 'SELECT COUNT(*) AS n FROM imm_anime'), 1);
+  } finally {
+    fs.rmSync(dir, { recursive: true, force: true });
+  }
+});
+
 test('matches shared videos by video_key and merges the watched flag', () => {
   const { dir, localPath, remotePath } = makeDbPair();
   try {

launcher/sync/sync-db.ts

@@ -35,7 +35,13 @@ export function mergeSnapshotIntoDb(localDbPath: string, snapshotPath: string):
   }
 
   const remote = new Database(snapshotPath, { readonly: true });
-  const local = new Database(localDbPath, { readwrite: true, create: false });
+  let local: Database;
+  try {
+    local = new Database(localDbPath, { readwrite: true, create: false });
+  } catch (error) {
+    remote.close();
+    throw error;
+  }
   try {
     assertMergeableSchema(remote, 'Snapshot');
     assertMergeableSchema(local, 'Local');

launcher/sync/sync-shared.ts

@@ -121,8 +121,10 @@ function isProcessAlive(pid: number): boolean {
   try {
     process.kill(pid, 0);
     return true;
-  } catch {
+  } catch (error) {
-    return false;
+    // EPERM means the process exists but we can't signal it → still alive.
+    // Only ESRCH (no such process) means it's actually gone.
+    return (error as NodeJS.ErrnoException)?.code === 'EPERM';
   }
 }