feat: report disk capacity on crash telemetry events

e2e-tests/performance_monitor.spec.ts

@@ -146,6 +146,16 @@ testWithConfig({})(
     expect(
       settings.lastKnownPerformance.systemCpuPercent,
     ).toBeGreaterThanOrEqual(0);
+    // statfs works on every platform we ship, so a real capture always has
+    // disk figures. Used never exceeds total; available can trail both.
+    expect(settings.lastKnownPerformance.diskTotalMB).toBeGreaterThan(0);
+    expect(settings.lastKnownPerformance.diskUsedMB).toBeGreaterThan(0);
+    expect(settings.lastKnownPerformance.diskUsedMB).toBeLessThanOrEqual(
+      settings.lastKnownPerformance.diskTotalMB,
+    );
+    expect(settings.lastKnownPerformance.diskAvailableMB).toBeLessThanOrEqual(
+      settings.lastKnownPerformance.diskTotalMB,
+    );
 
     // Verify the timestamp is recent (within the last minute)
     const now = Date.now();

src/lib/schemas.ts

@@ -352,6 +352,12 @@ export const LastKnownPerformanceSchema = z.object({
   systemMemoryUsageMB: z.number().optional(),
   systemMemoryTotalMB: z.number().optional(),
   systemCpuPercent: z.number().optional(),
+  // Capacity of the volume holding the user data directory. diskUsedMB counts
+  // every allocated block; diskAvailableMB excludes space the platform holds
+  // back (root reserve, quota), so the two need not sum to diskTotalMB.
+  diskTotalMB: z.number().optional(),
+  diskUsedMB: z.number().optional(),
+  diskAvailableMB: z.number().optional(),
   // Main process V8 heap, from v8.getHeapStatistics().
   heapUsedMB: z.number().optional(),
   heapLimitMB: z.number().optional(),

src/utils/crash_telemetry_fields.test.ts

@@ -12,6 +12,9 @@ describe("crashPerformanceEventFields", () => {
       memoryUsageMB: 400,
       heapUsedMB: 512,
       heapLimitMB: 4144,
+      diskTotalMB: 476000,
+      diskUsedMB: 401000,
+      diskAvailableMB: 51000,
       processWorkingSetsMB: { browser: 400, tab: 900, zygote: 30, unknown: 20 },
       activity: {
         activeStreams: 1,
@@ -45,6 +48,11 @@ describe("crashPerformanceEventFields", () => {
     expect(fields.peak_active_streams).toBe(2);
     expect(fields.peak_ts_utility_process).toBeNull();
     expect(fields.peak_heap_used_mb).toBe(1024);
+    expect(fields.last_known_disk_total_mb).toBe(476000);
+    expect(fields.last_known_disk_used_mb).toBe(401000);
+    // Reported separately from used because space the platform withholds
+    // sits between them: used + available is short of total.
+    expect(fields.last_known_disk_available_mb).toBe(51000);
 
     // No object-valued properties: PostHog cannot filter nested JSON.
     for (const value of Object.values(fields)) {
@@ -60,6 +68,7 @@ describe("crashPerformanceEventFields", () => {
 
     expect(fields.last_known_memory_mb).toBe(400);
     expect(fields.last_known_working_set_browser_mb).toBeUndefined();
+    expect(fields.last_known_disk_total_mb).toBeUndefined();
     expect(fields.last_known_active_streams).toBeUndefined();
     expect(fields.peak_active_streams).toBeUndefined();
   });

src/utils/crash_telemetry_fields.ts

@@ -24,6 +24,9 @@ export function crashPerformanceEventFields(
     last_known_system_memory_mb: perf.systemMemoryUsageMB,
     last_known_system_memory_total_mb: perf.systemMemoryTotalMB,
     last_known_system_cpu_pct: perf.systemCpuPercent,
+    last_known_disk_total_mb: perf.diskTotalMB,
+    last_known_disk_used_mb: perf.diskUsedMB,
+    last_known_disk_available_mb: perf.diskAvailableMB,
     last_known_snapshot_timestamp: perf.timestamp,
     time_since_last_heartbeat_ms: Date.now() - perf.timestamp,
     last_known_heap_used_mb: perf.heapUsedMB,

src/utils/disk_usage.test.ts

@@ -0,0 +1,63 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import fs from "node:fs";
+import { getDiskUsageMB } from "@/utils/disk_usage";
+
+vi.mock("node:fs", () => ({
+  default: { statfsSync: vi.fn() },
+}));
+
+const statfsSync = vi.mocked(fs.statfsSync);
+
+// 4KiB blocks: 262144 total = 1024MB, 65536 free = 256MB, 32768 available
+// to non-root = 128MB. The gap between free and available is the reserve.
+function statfsResult(overrides: Partial<fs.StatsFs> = {}): fs.StatsFs {
+  return {
+    type: 61267,
+    bsize: 4096,
+    blocks: 262144,
+    bfree: 65536,
+    bavail: 32768,
+    files: 0,
+    ffree: 0,
+    ...overrides,
+  } as fs.StatsFs;
+}
+
+describe("getDiskUsageMB", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("converts blocks to MB and reports used and available separately", () => {
+    statfsSync.mockReturnValue(statfsResult());
+
+    expect(getDiskUsageMB("/some/path")).toEqual({
+      totalMB: 1024,
+      // Every allocated block, including the root reserve.
+      usedMB: 768,
+      // Excludes the reserve, so used + available is short of total.
+      availableMB: 128,
+    });
+    expect(statfsSync).toHaveBeenCalledExactlyOnceWith("/some/path");
+  });
+
+  it("scales with the filesystem's block size", () => {
+    statfsSync.mockReturnValue(
+      statfsResult({ bsize: 1024, blocks: 2048, bfree: 1024, bavail: 1024 }),
+    );
+
+    expect(getDiskUsageMB("/some/path")).toEqual({
+      totalMB: 2,
+      usedMB: 1,
+      availableMB: 1,
+    });
+  });
+
+  it("returns null when the path cannot be read", () => {
+    statfsSync.mockImplementation(() => {
+      throw new Error("ENOENT");
+    });
+
+    expect(getDiskUsageMB("/missing")).toBeNull();
+  });
+});

src/utils/disk_usage.ts

@@ -0,0 +1,31 @@
+import fs from "node:fs";
+
+const BYTES_PER_MB = 1024 * 1024;
+
+export interface DiskUsageMB {
+  totalMB: number;
+  usedMB: number;
+  availableMB: number;
+}
+
+/**
+ * Capacity of the filesystem holding `targetPath`, from one statfs syscall.
+ * usedMB counts every allocated block, while availableMB is what this user
+ * can actually write and is lower wherever the platform holds space back —
+ * a root reserve, a per-user quota. Returns null when the path is unreadable
+ * so callers can omit the fields rather than report a zero.
+ */
+export function getDiskUsageMB(targetPath: string): DiskUsageMB | null {
+  try {
+    const stats = fs.statfsSync(targetPath);
+    const toMB = (blocks: number) =>
+      Math.round((blocks * stats.bsize) / BYTES_PER_MB);
+    return {
+      totalMB: toMB(stats.blocks),
+      usedMB: toMB(stats.blocks - stats.bfree),
+      availableMB: toMB(stats.bavail),
+    };
+  } catch {
+    return null;
+  }
+}

src/utils/performance_monitor.ts

@@ -10,6 +10,8 @@ import {
 import { getActiveStreamCount } from "../ipc/handlers/chat_stream_handlers";
 import { runningApps } from "../ipc/utils/process_manager";
 import { typescriptUtilityProcessScheduler } from "../ipc/processors/typescript_utility_process_scheduler";
+import { getUserDataPath } from "../paths/paths";
+import { getDiskUsageMB } from "./disk_usage";
 
 const logger = log.scope("performance-monitor");
 
@@ -231,6 +233,9 @@ function capturePerformanceMetrics() {
         : 0;
     const kernelPeakRssMB = getKernelPeakRssMB();
     const activity = snapshotActivity();
+    // The user data volume, not the apps volume: writeSettings below already
+    // blocks on it every tick, so this adds no new main-thread exposure.
+    const diskUsage = getDiskUsageMB(getUserDataPath());
 
     logger.debug(
       `Performance: Memory=${memoryUsageMB}MB, Heap=${heapUsedMB}/${heapLimitMB}MB, All Processes=${allProcessesMemoryMB ?? "?"}MB, CPU=${cpuUsagePercent}%, System Memory=${systemMemory.usedMemoryMB}/${systemMemory.totalMemoryMB}MB (${systemMemory.usagePercent}%), System CPU=${systemCpuPercent}%`,
@@ -271,6 +276,11 @@ function capturePerformanceMetrics() {
         systemMemoryUsageMB: systemMemory.usedMemoryMB,
         systemMemoryTotalMB: systemMemory.totalMemoryMB,
         systemCpuPercent,
+        ...(diskUsage && {
+          diskTotalMB: diskUsage.totalMB,
+          diskUsedMB: diskUsage.usedMB,
+          diskAvailableMB: diskUsage.availableMB,
+        }),
         heapUsedMB,
         heapLimitMB,
         ...(processWorkingSetsMB && { processWorkingSetsMB }),