diff --git a/src/main/runtime/device-registry-corruption.ts b/src/main/runtime/device-registry-corruption.ts
index 7e13f3818ff..253972954f9 100644
--- a/src/main/runtime/device-registry-corruption.ts
+++ b/src/main/runtime/device-registry-corruption.ts
@@ -15,14 +15,17 @@ export function corruptRegistryCopyExists(registryPath: string): boolean {
   }
 }
 
-export function quarantineCorruptRegistry(registryPath: string): void {
+/** True when this call moved the file aside; false when it was already gone. */
+export function quarantineCorruptRegistry(registryPath: string): boolean {
   const target = join(dirname(registryPath), `${corruptCopyPrefix(registryPath)}${Date.now()}`)
   try {
     renameSync(registryPath, target)
+    return true
   } catch (error) {
     if (!isMissingFileError(error)) {
       throw error
     }
+    return false
   }
 }
 
diff --git a/src/main/runtime/device-registry-disk-merge.ts b/src/main/runtime/device-registry-disk-merge.ts
index 70bdd5a4d77..06c962eff00 100644
--- a/src/main/runtime/device-registry-disk-merge.ts
+++ b/src/main/runtime/device-registry-disk-merge.ts
@@ -1,5 +1,6 @@
 import { writeDurableSecureJsonFile, writeSecureJsonFile } from '../../shared/secure-file'
 import type { DeviceEntry } from './device-entry'
+import { quarantineCorruptRegistry } from './device-registry-corruption'
 import { readDeviceRegistryFile, type DeviceRegistryFileRead } from './device-registry-file-read'
 
 /**
@@ -29,14 +30,22 @@ export function mergeDeviceRegistrySave(
  * Writes saves merged over the file as it is now (atomically, through the secure-file stage and
  * rename). Remembers every id this process removed, recorded before the write so a failed save
  * (such as the load-time cleanup of session-only rows) still counts: a stale writer putting one of
- * those back must not get it re-adopted. A file that became unreadable or corrupt proves nothing
- * about removals, so then the save is written as is, as before.
+ * those back must not get it re-adopted. A file that became unreadable or corrupt, or that this
+ * process quarantined itself, proves nothing about removals, so then the save is written as is.
  */
 export class DeviceRegistryWriter {
   private readonly removedIds = new Set<string>()
+  /** This process moved the file aside and no write has landed since: its absence is ours, not a revoke. */
+  private quarantinedUntilWritten = false
 
   constructor(private readonly registryPath: string) {}
 
+  quarantineCorrupt(): void {
+    if (quarantineCorruptRegistry(this.registryPath)) {
+      this.quarantinedUntilWritten = true
+    }
+  }
+
   /** Returns what was written. Security transitions pass `durable`. */
   write(
     before: readonly DeviceEntry[],
@@ -49,13 +58,14 @@ export class DeviceRegistryWriter {
         this.removedIds.add(deviceId)
       }
     }
-    const disk = readDeviceRegistryFile(this.registryPath)
+    const disk = this.quarantinedUntilWritten ? null : readDeviceRegistryFile(this.registryPath)
     const merged =
-      disk.unreadable || disk.corruptFilePending
+      !disk || disk.unreadable || disk.corruptFilePending
         ? [...next]
         : mergeDeviceRegistrySave(before, next, disk, this.removedIds)
     const write = options.durable ? writeDurableSecureJsonFile : writeSecureJsonFile
     write(this.registryPath, merged)
+    this.quarantinedUntilWritten = false
     return merged
   }
 }
diff --git a/src/main/runtime/device-registry-own-quarantine.test.ts b/src/main/runtime/device-registry-own-quarantine.test.ts
new file mode 100644
index 00000000000..d55e55ef24d
--- /dev/null
+++ b/src/main/runtime/device-registry-own-quarantine.test.ts
@@ -0,0 +1,107 @@
+// A load that drops an unreadable row (e.g. one a newer Orca wrote) quarantines the file at the
+// first save; that missing file is this process's own doing and must not revoke the valid rows.
+import { existsSync, mkdtempSync, readdirSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import * as secureFile from '../../shared/secure-file'
+import { DeviceRegistry } from './device-registry'
+import { DEVICE_REGISTRY_FILENAME } from './mobile-pairing-files'
+
+let dir: string
+
+beforeEach(() => {
+  dir = mkdtempSync(join(tmpdir(), 'orca-device-registry-quarantine-'))
+})
+
+afterEach(() => {
+  vi.restoreAllMocks()
+  rmSync(dir, { recursive: true, force: true })
+})
+
+function registryPath(): string {
+  return join(dir, DEVICE_REGISTRY_FILENAME)
+}
+
+function fileIds(): string[] {
+  const rows: { deviceId: string }[] = JSON.parse(readFileSync(registryPath(), 'utf8'))
+  return rows.map((row) => row.deviceId)
+}
+
+function quarantinedCopies(): string[] {
+  return readdirSync(dir).filter((name) => name.startsWith(`${DEVICE_REGISTRY_FILENAME}.corrupt-`))
+}
+
+/** A paired, seen phone in a file that also holds a row this build can't read. */
+function partiallyCorruptRegistry() {
+  const first = new DeviceRegistry(dir)
+  const phone = first.addDevice('phone', 'mobile')
+  first.updateLastSeen(phone.deviceId)
+  const rows: unknown[] = JSON.parse(readFileSync(registryPath(), 'utf8'))
+  writeFileSync(registryPath(), JSON.stringify([...rows, { deviceId: 'x', bogus: true }]))
+  const registry = new DeviceRegistry(dir)
+  expect(registry.validateToken(phone.token)?.deviceId).toBe(phone.deviceId)
+  return { registry, phone }
+}
+
+describe('device registry after quarantining its own corrupt file', () => {
+  it('keeps every valid device through the first save', () => {
+    const { registry, phone } = partiallyCorruptRegistry()
+
+    const added = registry.addDevice('new desktop', 'runtime')
+
+    expect(quarantinedCopies()).toHaveLength(1)
+    expect(fileIds()).toEqual([phone.deviceId, added.deviceId])
+    expect(registry.validateToken(phone.token)?.deviceId).toBe(phone.deviceId)
+    expect(new DeviceRegistry(dir).validateToken(phone.token)?.deviceId).toBe(phone.deviceId)
+  })
+
+  it('keeps them when the write after the quarantine failed, on the next save', () => {
+    const { registry, phone } = partiallyCorruptRegistry()
+    vi.spyOn(secureFile, 'writeSecureJsonFile').mockImplementationOnce(() => {
+      throw new Error('disk full')
+    })
+
+    expect(() => registry.addDevice('new desktop', 'runtime')).toThrow('disk full')
+    expect(quarantinedCopies()).toHaveLength(1)
+    expect(existsSync(registryPath())).toBe(false)
+    const added = registry.addDevice('new desktop', 'runtime')
+
+    expect(fileIds()).toEqual([phone.deviceId, added.deviceId])
+    expect(registry.validateToken(phone.token)?.deviceId).toBe(phone.deviceId)
+  })
+
+  it('still revokes everything when the file is deleted after its own write landed', () => {
+    const { registry, phone } = partiallyCorruptRegistry()
+    registry.addDevice('new desktop', 'runtime')
+
+    rmSync(registryPath())
+    const added = registry.addDevice('second desktop', 'runtime')
+
+    expect(fileIds()).toEqual([added.deviceId])
+    expect(registry.validateToken(phone.token)).toBeNull()
+  })
+
+  it('revokes everything when an intact file is deleted, as before', () => {
+    const registry = new DeviceRegistry(dir)
+    const phone = registry.addDevice('phone', 'mobile')
+
+    rmSync(registryPath())
+    const added = registry.addDevice('desktop', 'runtime')
+
+    expect(fileIds()).toEqual([added.deviceId])
+    expect(registry.getDevice(phone.deviceId)).toBeNull()
+    expect(registry.validateToken(phone.token)).toBeNull()
+  })
+
+  it('treats a corrupt file deleted by someone else before the quarantine as a revoke', () => {
+    const { registry, phone } = partiallyCorruptRegistry()
+
+    rmSync(registryPath())
+    const added = registry.addDevice('new desktop', 'runtime')
+
+    expect(quarantinedCopies()).toEqual([])
+    expect(fileIds()).toEqual([added.deviceId])
+    expect(registry.validateToken(phone.token)).toBeNull()
+  })
+})
diff --git a/src/main/runtime/device-registry.ts b/src/main/runtime/device-registry.ts
index 8d533733fbf..397e48e34ab 100644
--- a/src/main/runtime/device-registry.ts
+++ b/src/main/runtime/device-registry.ts
@@ -6,7 +6,6 @@ import { DEVICE_REGISTRY_FILENAME } from './mobile-pairing-files'
 import { mintDeviceCredential } from './device-credential'
 import { planDeviceKeyFork } from './device-key-fork'
 import { planIdleEphemeralPrune, withoutEphemeralRows } from './ephemeral-device-rows'
-import { quarantineCorruptRegistry } from './device-registry-corruption'
 import { readDeviceRegistryFile } from './device-registry-file-read'
 import { DeviceRegistryWriter } from './device-registry-disk-merge'
 import type { RelayDeviceBinding } from './mobile-cloud-relay/relay-revoke-outbox'
@@ -339,7 +338,7 @@ export class DeviceRegistry {
       )
     }
     if (this.corruptFilePending) {
-      quarantineCorruptRegistry(this.registryPath)
+      this.writer.quarantineCorrupt()
       this.corruptFilePending = false
     }
   }