fix(crash-reporting): co-time the statfs by tick, not sample identity

A tick whose host read fails leaves the pre-gone sample object in place, so
the identity check still read a 25 s-late statfs as co-timed.

src/main/crash-reporting/pre-gone-host-memory.test.ts

@@ -241,6 +241,43 @@ describe('pre-gone host memory', () => {
     }
   })
 
+  // Round 5: sample identity alone could not see these ticks. A host read that
+  // returns nothing leaves the sample object in place, so `sample === issuedFor`
+  // still held 25 s and two ticks later and the statfs re-qualified the verdict.
+  it('will not let ticks with a failed host read pass a stale statfs off as co-timed', async () => {
+    const platform = Object.getOwnPropertyDescriptor(process, 'platform')!
+    Object.defineProperty(process, 'platform', { configurable: true, value: 'win32' })
+    vi.useFakeTimers()
+    let resolveVolume: (value: SwapVolumeFreeSpace) => void = () => {}
+    try {
+      setSystemMemoryInfoReaderForTest(() => BEFORE_THE_STORM)
+      setSwapVolumeFreeSpaceReaderForTest(
+        () =>
+          new Promise<SwapVolumeFreeSpace>((resolve) => {
+            resolveVolume = resolve
+          })
+      )
+      void samplePreGoneSystemMemory(0)
+
+      // GlobalMemoryStatusEx starts failing: the sample is neither replaced nor erased.
+      setSystemMemoryInfoReaderForTest(() => null)
+      await samplePreGoneSystemMemory(10_000)
+      await samplePreGoneSystemMemory(20_000)
+
+      resolveVolume({ freeMB: 40_000, volume: 'C:' })
+      await vi.advanceTimersByTimeAsync(0)
+
+      vi.setSystemTime(25_000)
+      const details = buildProcessGoneCrashDetails({}, 'renderer')
+      // 25 s of lag: the label must not say co-timed beside that age.
+      expect(details.systemMemoryPreGoneSwapVolumeAgeMs).toBe(25_000)
+      expect(details.systemMemoryPreGonePressureSignal).toBe('available-commit-unqualified')
+    } finally {
+      vi.useRealTimers()
+      Object.defineProperty(process, 'platform', platform)
+    }
+  })
+
   it("arms the host sampler on its own unref'd 10 s timer, not the metric sweep's", async () => {
     vi.useFakeTimers()
     vi.setSystemTime(0)

src/main/crash-reporting/pre-gone-host-memory.ts

@@ -30,6 +30,7 @@ let preGoneSample: PreGoneSystemMemorySample | null = null
 let preGoneTimer: ReturnType<typeof setInterval> | null = null
 let swapVolumeReadInFlight = false
 let samplingGeneration = 0
+let sampleTick = 0
 
 const PRESSURE_SIGNAL_KEY = `${SYSTEM_MEMORY_KEY_PREFIX}PressureSignal`
 
@@ -74,7 +75,7 @@ function commitHostMemorySample(nowMs: number): boolean {
   }
 }
 
-async function mergeSwapVolumeFreeSpace(): Promise<void> {
+async function mergeSwapVolumeFreeSpace(issuedOnTick: number): Promise<void> {
   if (swapVolumeReadInFlight) {
     return
   }
@@ -87,7 +88,9 @@ async function mergeSwapVolumeFreeSpace(): Promise<void> {
       // Why only its own tick qualifies: a statfs that outlived its tick carries a
       // pre-storm volume number, and the latch makes that lag unbounded. It still
       // ships beside its age, but it may not decide the verdict.
-      const coTimed = preGoneSample === issuedFor
+      // Why the tick counter and not sample identity: a tick whose host read fails
+      // leaves the sample object in place, so identity alone reads as co-timed.
+      const coTimed = issuedOnTick === sampleTick
       preGoneSample = {
         ...preGoneSample,
         details: withSwapVolumeFreeSpace(preGoneSample.details, volume, process.platform, coTimed),
@@ -105,10 +108,11 @@ export async function samplePreGoneSystemMemory(nowMs: number = Date.now()): Pro
   // Why commit before awaiting: the volume read is a statfs, and under the very
   // paging storm this targets it is slowest — it must never delay, or (via an
   // in-flight latch) skip, the cheap synchronous host reading.
+  const tick = ++sampleTick
   if (!commitHostMemorySample(nowMs)) {
     return
   }
-  await mergeSwapVolumeFreeSpace()
+  await mergeSwapVolumeFreeSpace(tick)
 }
 
 export function startPreGoneSystemMemorySampling(