Derive the terminal IME platform from the renderer's own mapping

Enumerating platform names in a second place is what let one user agent
read as Linux everywhere except the policy that cared.

Co-authored-by: Orca <help@stably.ai>

src/renderer/src/components/terminal-pane/terminal-ime-platform.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from 'vitest'
+import { resolveShortcutPlatform } from '@/lib/shortcut-platform'
 import { resolveTerminalImePlatform } from './terminal-ime-platform'
 
 const DESKTOP_LINUX =
@@ -11,6 +12,8 @@ const MACOS =
   'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36'
 const WINDOWS =
   'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36'
+const FREEBSD =
+  'Mozilla/5.0 (X11; FreeBSD amd64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36'
 
 describe('resolveTerminalImePlatform', () => {
   it('treats desktop Linux as both Chromium-family and ibus/fcitx-bearing', () => {
@@ -44,4 +47,25 @@ describe('resolveTerminalImePlatform', () => {
       isDesktopLinux: false
     })
   })
+
+  // Only Windows has a reason to suppress a standalone 229, so an unrecognised desktop
+  // belongs on the passing side rather than in whichever bucket a UA guess lands it in.
+  it('treats an unrecognised desktop as Linux', () => {
+    expect(resolveTerminalImePlatform(FREEBSD)).toEqual({
+      isMac: false,
+      isLinux: true,
+      isDesktopLinux: true
+    })
+  })
+
+  it.each([DESKTOP_LINUX, CHROME_OS, ANDROID, MACOS, WINDOWS, FREEBSD])(
+    'agrees with the renderer-wide platform mapping (%#)',
+    (userAgent) => {
+      const { isMac, isLinux } = resolveTerminalImePlatform(userAgent)
+      expect({ isMac, isLinux }).toEqual({
+        isMac: resolveShortcutPlatform(userAgent) === 'darwin',
+        isLinux: resolveShortcutPlatform(userAgent) === 'linux'
+      })
+    }
+  )
 })

src/renderer/src/components/terminal-pane/terminal-ime-platform.ts

@@ -1,30 +1,34 @@
+import { resolveShortcutPlatform } from '@/lib/shortcut-platform'
+
 export type TerminalImePlatform = {
   isMac: boolean
-  /** Chromium on a Linux kernel — ChromeOS and Android included. */
+  /** Everything that is neither macOS nor Windows, matching `getShortcutPlatform`. */
   isLinux: boolean
   /** Desktop Linux only — the platforms actually running ibus or fcitx. */
   isDesktopLinux: boolean
 }
 
-// ChromeOS reports `X11; CrOS x86_64`, with no "Linux" anywhere in it, so a plain
-// substring test puts it on the Windows side of every policy below.
-const LINUX_KERNEL_PLATFORM = /Linux|CrOS/
 const NON_DESKTOP_LINUX_PLATFORM = /Android|CrOS/
 
 /**
  * Splits the two platform questions the terminal's IME policy asks, which are not the
  * same question and had been sharing one answer.
  *
- * Standalone keydown 229 is Chromium-family behavior, so ChromeOS and Android belong
- * with desktop Linux. The candidate-key guards read ibus/fcitx specifics that neither
- * shares, so they are scoped tighter. Deriving both here keeps one user agent from
- * getting two different platform verdicts in two different files.
+ * Standalone keydown 229 is really a question about Windows, whose preedit-diff race is
+ * the only reason to suppress it, so every other platform passes. Sharing the renderer's
+ * one user-agent mapping is what keeps that set from drifting: enumerating Linux-ish
+ * user agents here instead is how ChromeOS — which reports `X11; CrOS x86_64`, with no
+ * "Linux" in it — ended up on the Windows side of this policy while the rest of the
+ * renderer treated it as Linux.
+ *
+ * The candidate-key guards read ibus/fcitx specifics that ChromeOS and Android do not
+ * share, so they are scoped tighter. That narrowing is the only intended difference.
  */
 export function resolveTerminalImePlatform(userAgent: string): TerminalImePlatform {
-  const isMac = userAgent.includes('Mac')
-  const isLinux = !isMac && LINUX_KERNEL_PLATFORM.test(userAgent)
+  const platform = resolveShortcutPlatform(userAgent)
+  const isLinux = platform === 'linux'
   return {
-    isMac,
+    isMac: platform === 'darwin',
     isLinux,
     isDesktopLinux: isLinux && !NON_DESKTOP_LINUX_PLATFORM.test(userAgent)
   }

src/renderer/src/lib/shortcut-platform.ts

@@ -1,6 +1,11 @@
-export function getShortcutPlatform(): NodeJS.Platform {
-  if (navigator.userAgent.includes('Mac')) {
+/** Maps a user agent to the platform whose conventions the renderer should follow. */
+export function resolveShortcutPlatform(userAgent: string): NodeJS.Platform {
+  if (userAgent.includes('Mac')) {
     return 'darwin'
   }
-  return navigator.userAgent.includes('Windows') ? 'win32' : 'linux'
+  return userAgent.includes('Windows') ? 'win32' : 'linux'
+}
+
+export function getShortcutPlatform(): NodeJS.Platform {
+  return resolveShortcutPlatform(navigator.userAgent)
 }