fix(desktop): create control-socket dir before opening the SSH master

OpenSSH does not create intermediate directories for ControlPath, so on a fresh
box (no prior hermes-desktop-ssh dir under \$TMPDIR) the very first connect failed
when ssh tried to create the master socket. Unit tests mock spawn and never hit
real fs, so this was invisible.

open() now mkdir -p (mode 0700 — the socket grants command execution on the
master) the control-socket directory before spawning ssh. Mirrors ssh.py.
Added a test that open() creates a non-existent control dir.

apps/desktop/electron/ssh-connection.cjs

@@ -36,6 +36,7 @@ const crypto = require('node:crypto')
 const net = require('node:net')
 const os = require('node:os')
 const path = require('node:path')
+const fs = require('node:fs')
 
 const DEFAULT_CONNECT_TIMEOUT_MS = 15_000
 const DEFAULT_EXEC_TIMEOUT_MS = 20_000
@@ -354,6 +355,15 @@ class SshConnection {
       this._opened = true
       return
     }
+    // Ensure the control-socket directory exists — OpenSSH will not create
+    // intermediate dirs for ControlPath, so a fresh box (no prior hermes-ssh
+    // socket dir under $TMPDIR) would otherwise fail before the first connect.
+    // 0o700: the socket grants command execution on the master; keep it private.
+    try {
+      fs.mkdirSync(path.dirname(this.controlPath), { recursive: true, mode: 0o700 })
+    } catch {
+      // best effort — a pre-existing dir or a races-with-another-conn mkdir is fine
+    }
     const args = buildMasterArgs(this, this._connectTimeoutMs)
     this._logLine(`opening control master to ${target(this.user, this.host)}:${this.port}`)
     let result

apps/desktop/electron/ssh-connection.test.cjs

@@ -12,6 +12,9 @@
 const test = require('node:test')
 const assert = require('node:assert/strict')
 const { EventEmitter } = require('node:events')
+const fs = require('node:fs')
+const os = require('node:os')
+const path = require('node:path')
 
 const {
   SSH_ERROR,
@@ -247,6 +250,23 @@ test('open() is a no-op when the master is already alive', async () => {
   assert.deepEqual(ops, ['check'], 'alive master → no second spawn to open it')
 })
 
+test('open() creates the control-socket directory if it does not exist', async () => {
+  const dir = path.join(os.tmpdir(), `hermes-ssh-test-${process.pid}-${Date.now()}`)
+  assert.ok(!fs.existsSync(dir), 'precondition: control dir absent')
+  const spawnFn = scriptedSpawn(args => (args.includes('check') ? { code: 255 } : { code: 0 }))
+  const conn = new SshConnection({ host: 'box', user: 'me' }, { spawnFn, controlDir: dir })
+  try {
+    await conn.open()
+    assert.ok(fs.existsSync(dir), 'open() created the control-socket directory before spawning ssh')
+  } finally {
+    try {
+      fs.rmSync(dir, { recursive: true, force: true })
+    } catch {
+      /* ignore */
+    }
+  }
+})
+
 test('open() surfaces a classified auth error', async () => {
   const spawnFn = scriptedSpawn(args => {
     if (args.includes('check')) return { code: 255 }