refactor(desktop): extract desktop-log IPC handlers from main.cjs into logs-ipc.cjs

Fifth main.cjs cluster peel. The two hermes:logs:* handlers (reveal, recent) move
verbatim into electron/logs-ipc.cjs behind a registerLogsIpc({ ipcMain,
DESKTOP_LOG_PATH, hermesLog, fileExists }) registrar. The log path and the
in-memory ring buffer live in the main process and are injected.

Channel names unchanged → preload + renderer untouched. Adds
electron/logs-ipc.test.cjs (surface invariant + recent-tail behavior).

apps/desktop/electron/logs-ipc.cjs

@@ -0,0 +1,27 @@
+'use strict'
+
+const { shell } = require('electron')
+const fs = require('fs')
+const path = require('path')
+
+// Desktop-log IPC: reveal the log file in the OS file manager + return the
+// recent in-memory tail. The log path, the in-memory ring buffer, and the
+// file-exists probe live in the main process and are injected.
+function registerLogsIpc({ DESKTOP_LOG_PATH, fileExists, hermesLog, ipcMain }) {
+  ipcMain.handle('hermes:logs:reveal', async () => {
+    try {
+      await fs.promises.mkdir(path.dirname(DESKTOP_LOG_PATH), { recursive: true })
+      if (!fileExists(DESKTOP_LOG_PATH)) {
+        await fs.promises.appendFile(DESKTOP_LOG_PATH, '')
+      }
+      shell.showItemInFolder(DESKTOP_LOG_PATH)
+      return { ok: true, path: DESKTOP_LOG_PATH }
+    } catch (error) {
+      return { ok: false, path: DESKTOP_LOG_PATH, error: error.message }
+    }
+  })
+
+  ipcMain.handle('hermes:logs:recent', async () => ({ path: DESKTOP_LOG_PATH, lines: hermesLog.slice(-200) }))
+}
+
+module.exports = { registerLogsIpc }

apps/desktop/electron/logs-ipc.test.cjs

@@ -0,0 +1,44 @@
+'use strict'
+
+const assert = require('node:assert/strict')
+const test = require('node:test')
+
+const { registerLogsIpc } = require('./logs-ipc.cjs')
+
+function fakeIpcMain() {
+  const handlers = new Map()
+
+  return {
+    handlers,
+    handle(channel, handler) {
+      assert.ok(!handlers.has(channel), `duplicate registration for ${channel}`)
+      handlers.set(channel, handler)
+    }
+  }
+}
+
+test('registerLogsIpc wires only hermes:logs:* channels, each to a handler fn', () => {
+  const ipcMain = fakeIpcMain()
+
+  registerLogsIpc({ ipcMain, DESKTOP_LOG_PATH: '/tmp/desktop.log', fileExists: () => true, hermesLog: [] })
+
+  assert.deepEqual([...ipcMain.handlers.keys()].sort(), ['hermes:logs:recent', 'hermes:logs:reveal'])
+
+  for (const handler of ipcMain.handlers.values()) {
+    assert.equal(typeof handler, 'function')
+  }
+})
+
+test('logs:recent returns the injected path and the last 200 buffered lines', async () => {
+  const ipcMain = fakeIpcMain()
+  const hermesLog = Array.from({ length: 250 }, (_, i) => `line ${i}`)
+
+  registerLogsIpc({ ipcMain, DESKTOP_LOG_PATH: '/tmp/desktop.log', fileExists: () => true, hermesLog })
+
+  const res = await ipcMain.handlers.get('hermes:logs:recent')({})
+
+  assert.equal(res.path, '/tmp/desktop.log')
+  assert.equal(res.lines.length, 200)
+  assert.equal(res.lines[0], 'line 50')
+  assert.equal(res.lines.at(-1), 'line 249')
+})

apps/desktop/electron/main.cjs

@@ -60,6 +60,7 @@ const { registerGitIpc } = require('./git-ipc.cjs')
 const { registerFsIpc } = require('./fs-ipc.cjs')
 const { registerTerminalIpc } = require('./terminal-ipc.cjs')
 const { registerUpdatesIpc } = require('./updates-ipc.cjs')
+const { registerLogsIpc } = require('./logs-ipc.cjs')
 const { OFFICIAL_REPO_HTTPS_URL, isOfficialSshRemote } = require('./update-remote.cjs')
 const { resolveBehindCount, shouldCountCommits } = require('./update-count.cjs')
 const { runRebuildWithRetry } = require('./update-rebuild.cjs')
@@ -6702,20 +6703,8 @@ ipcMain.handle('hermes:setting:defaultProjectDir:pick', async () => {
 
 ipcMain.handle('hermes:fetchLinkTitle', (_event, url) => fetchLinkTitle(url))
 
-ipcMain.handle('hermes:logs:reveal', async () => {
-  try {
-    await fs.promises.mkdir(path.dirname(DESKTOP_LOG_PATH), { recursive: true })
-    if (!fileExists(DESKTOP_LOG_PATH)) {
-      await fs.promises.appendFile(DESKTOP_LOG_PATH, '')
-    }
-    shell.showItemInFolder(DESKTOP_LOG_PATH)
-    return { ok: true, path: DESKTOP_LOG_PATH }
-  } catch (error) {
-    return { ok: false, path: DESKTOP_LOG_PATH, error: error.message }
-  }
-})
-
-ipcMain.handle('hermes:logs:recent', async () => ({ path: DESKTOP_LOG_PATH, lines: hermesLog.slice(-200) }))
+// Desktop-log IPC lives in logs-ipc.cjs; log path + ring buffer are injected.
+registerLogsIpc({ DESKTOP_LOG_PATH, fileExists, hermesLog, ipcMain })
 
 function isExecutableFile(filePath) {
   if (!filePath || !path.isAbsolute(filePath)) {