diff --git a/apps/desktop/electron/linux-crash-diagnostics.test.ts b/apps/desktop/electron/linux-crash-diagnostics.test.ts
new file mode 100644
index 0000000000..68d13b4511
--- /dev/null
+++ b/apps/desktop/electron/linux-crash-diagnostics.test.ts
@@ -0,0 +1,33 @@
+import assert from 'node:assert/strict'
+import path from 'node:path'
+
+import { test } from 'vitest'
+
+import { linuxCrashDiagnostics } from './linux-crash-diagnostics'
+
+// Regression for #100573: the Linux shell died with SIGTRAP at Chromium's
+// shared fatal-handler address and no launcher kept the FATAL message. The
+// fix is not a guess at the cause; it is making the next crash legible.
+
+test('on linux, fatal Chromium output lands in a file under the Hermes logs dir', () => {
+  const plan = linuxCrashDiagnostics('/home/u/.hermes/logs', 'linux')
+
+  assert.ok(plan)
+
+  const switches = new Map(plan.switches)
+
+  assert.equal(switches.get('enable-logging'), 'file')
+
+  const logFile = switches.get('log-file')
+
+  assert.ok(logFile)
+  assert.equal(path.dirname(logFile), '/home/u/.hermes/logs')
+  // FATAL (3) must survive the level filter; anything stricter would drop it.
+  assert.ok(Number(switches.get('log-level')) <= 3)
+  assert.equal(plan.crashReporter.uploadToServer, false)
+})
+
+test('other platforms get no Chromium logging switches and no crash reporter', () => {
+  assert.equal(linuxCrashDiagnostics('/Users/u/.hermes/logs', 'darwin'), null)
+  assert.equal(linuxCrashDiagnostics('C:\\Users\\u\\.hermes\\logs', 'win32'), null)
+})
diff --git a/apps/desktop/electron/linux-crash-diagnostics.ts b/apps/desktop/electron/linux-crash-diagnostics.ts
new file mode 100644
index 0000000000..abd80ee6a6
--- /dev/null
+++ b/apps/desktop/electron/linux-crash-diagnostics.ts
@@ -0,0 +1,41 @@
+import path from 'node:path'
+
+// Every Chromium CHECK/LOG(FATAL) in the shell ends at the same instruction —
+// base::ImmediateCrash at the tail of logging::LogMessage::HandleFatal — so a
+// core dump alone says "something fatal happened" and nothing about what
+// (#100573: ten Linux reports, one shared trap address, zero fatal messages).
+// The message itself goes to stderr a moment before the trap, and every Linux
+// launcher (.desktop entry, Omarchy's hermes-desktop wrapper) discards stderr.
+// Route Chromium's own log to a file next to desktop.log and let Crashpad keep
+// local minidumps, so the next crash carries its FATAL line with it.
+
+export interface LinuxCrashDiagnostics {
+  /** Chromium command-line switches, applied before `app` is ready. */
+  switches: ReadonlyArray<readonly [name: string, value: string]>
+  /** `crashReporter.start` options; local database only, nothing leaves the machine. */
+  crashReporter: { uploadToServer: false; compress: false }
+}
+
+// Chromium log severities: 0 INFO, 1 WARNING, 2 ERROR, 3 FATAL. ERROR keeps the
+// file quiet during normal use (INFO would mirror every renderer console line).
+const CHROMIUM_LOG_LEVEL_ERROR = '2'
+
+export const CHROMIUM_LOG_FILENAME = 'desktop-chromium.log'
+
+export function linuxCrashDiagnostics(
+  logsDir: string,
+  platform: NodeJS.Platform = process.platform
+): LinuxCrashDiagnostics | null {
+  if (platform !== 'linux') {
+    return null
+  }
+
+  return {
+    switches: [
+      ['enable-logging', 'file'],
+      ['log-file', path.join(logsDir, CHROMIUM_LOG_FILENAME)],
+      ['log-level', CHROMIUM_LOG_LEVEL_ERROR]
+    ],
+    crashReporter: { uploadToServer: false, compress: false }
+  }
+}
diff --git a/apps/desktop/electron/main.ts b/apps/desktop/electron/main.ts
index 6318ecc7dd..2cb9f80a08 100644
--- a/apps/desktop/electron/main.ts
+++ b/apps/desktop/electron/main.ts
@@ -12,6 +12,7 @@ import {
   app,
   BrowserWindow,
   clipboard,
+  crashReporter,
   dialog,
   net as electronNet,
   webContents as electronWebContents,
@@ -281,6 +282,7 @@ import type { InstallStamp } from './install-stamp'
 import { createIntroRevealWindowController } from './intro-reveal-window'
 import { isAuthWall, resolveLinkTitle } from './link-title-wall'
 import { createLinkTitleWindow, guardLinkTitleSession, readLinkTitleWindowTitle } from './link-title-window'
+import { linuxCrashDiagnostics } from './linux-crash-diagnostics'
 import { notifyLauncherWindowRevealed } from './linux-launcher-ready'
 import { createLocalBackendLifecycle, waitForTeardown } from './local-backend-lifecycle'
 import { registerMachineProfile } from './machine-profile'
@@ -871,6 +873,22 @@ const DESKTOP_LOG_MAX_BYTES = 10 * 1024 * 1024
 const DESKTOP_LOG_BACKUP_COUNT = 3
 const DESKTOP_LOG_DISCARD_BYTES = DESKTOP_LOG_MAX_BYTES * 4
 const desktopLogBackupPath = (n: number) => `${DESKTOP_LOG_PATH}.${n}`
+
+// #100573: keep the FATAL line and a local minidump for the next Linux SIGTRAP.
+// Both must be wired before `app` is ready; the log-file switch is inherited by
+// every child process, so a zygote or GPU CHECK lands in the same file.
+const CRASH_DIAGNOSTICS = linuxCrashDiagnostics(path.dirname(DESKTOP_LOG_PATH))
+
+if (CRASH_DIAGNOSTICS) {
+  fs.mkdirSync(path.dirname(DESKTOP_LOG_PATH), { recursive: true })
+
+  for (const [name, value] of CRASH_DIAGNOSTICS.switches) {
+    app.commandLine.appendSwitch(name, value)
+  }
+
+  crashReporter.start(CRASH_DIAGNOSTICS.crashReporter)
+}
+
 const BOOT_FAKE_MODE = process.env.HERMES_DESKTOP_BOOT_FAKE === '1'
 const BOOT_FAKE_ERROR = process.env.HERMES_DESKTOP_BOOT_FAKE_ERROR || ''
 // Automated teardown (Playwright's app.close(), harness scripts) quits with
diff --git a/website/docs/user-guide/desktop.md b/website/docs/user-guide/desktop.md
index e8b087b679..e5d05dfb1a 100644
--- a/website/docs/user-guide/desktop.md
+++ b/website/docs/user-guide/desktop.md
@@ -620,6 +620,8 @@ For a canonical source installation, Desktop checks and runs the installation
 launcher. PM selects its interpreter and dependency generation. A missing
 bootstrap marker does not force installation when that launcher works.
 
+On Linux, Chromium's own errors go to `HERMES_HOME/logs/desktop-chromium.log`, and a crash of the shell itself leaves a minidump under the app's `Crashpad/` directory (inside Electron's user-data directory, next to `connection.json`). If the window vanishes with `SIGTRAP` in the journal, the `FATAL:` line in that log names the check that fired; attach it to the bug report. Nothing is uploaded.
+
 If Python dependencies are damaged, run the installation's `hermes pm repair`.
 Then restart Desktop. Do not delete guessed `venv` paths or PM facts. For
 damaged application files, repair through the