Files
commitea/apps/desktop/src/main/snapshot-store.ts
Croissant Le Doux 73643efcbc Purity / rebuild guarantee test (#30)
The cache is a rebuildable index over gitea, never a source of truth (D4).
Two tests lock that invariant where the durable cache actually lives:

- packages/core: cache-purity-v0.test.ts — file-backed node:sqlite. Build the
  SQLite mirror from a gitea snapshot, capture every re-derived field, delete the
  .sqlite file, rebuild from the same snapshot, assert byte-identical. Plus a
  structural D4 guard: every issues-table column must map to a gitea field, so a
  future user-authored column can't silently break rebuild-ability.

- apps/desktop: snapshot-store.test.ts — the shipped durable cache is the JSON
  snapshot-store. Delete the file → loadSnapshot returns null (degrades to
  no-cache, never throws), which is what forces the next getSnapshot to reconcile
  fresh from gitea. Corrupt/partial files are likewise treated as no-cache.
  Stands up vitest for the desktop main process (first unit tests there);
  electron is mocked, snapshot path is injected.

No native better-sqlite3 shipped: the SQLite mirror has no consumer on any hot
path yet, so wiring it into main (native module + asarUnpack + dmg re-verify)
would add packaging risk for no runtime benefit. The purity invariant is proven
at the seam for both caches; the native driver migration is deferred until
SQLite becomes load-bearing.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-09 18:02:50 -04:00

53 lines
2.0 KiB
TypeScript

/**
* Durable snapshot store — the reconcile cache, persisted to disk. On boot the
* app shows the last snapshot instantly (stale-while-revalidate) instead of a
* blank board while ~2N gitea calls run; if gitea is unreachable, reads fall
* back to it (offline). It's a rebuildable mirror — the durable truth stays in
* gitea (the purity split, D4). A plain JSON file: the whole snapshot fits in
* memory at this scale, so indexed SQL buys nothing yet (see the PR).
*/
import { readFileSync, writeFileSync } from 'node:fs'
import { join } from 'node:path'
import { app } from 'electron'
/** The shape we persist — kept loose so a schema drift degrades to "no cache", not a crash. */
export interface PersistedSnapshot {
issues: unknown[]
milestones: unknown[]
deps: unknown[]
timelines: Record<number, unknown[]>
/** ISO time the snapshot was reconciled — shown as "cached since". */
savedAt: string
}
function snapshotPath(): string {
return join(app.getPath('userData'), 'commitea-snapshot.json')
}
/**
* Load the last persisted snapshot, or null if absent/corrupt. Never throws — a
* deleted or unreadable cache degrades to "no cache" (the purity guarantee, D4:
* the next reconcile rebuilds it from gitea). `path` is injectable for tests;
* production always uses the userData file.
*/
export function loadSnapshot(path: string = snapshotPath()): PersistedSnapshot | null {
try {
const parsed = JSON.parse(readFileSync(path, 'utf8')) as PersistedSnapshot
if (parsed && Array.isArray(parsed.issues)) return parsed
return null
} catch {
return null // missing file, bad JSON, or drift — treat as no cache
}
}
/** Persist a freshly reconciled snapshot. Best-effort — a write failure never breaks a reconcile. */
export function saveSnapshot(snap: Omit<PersistedSnapshot, 'savedAt'>, savedAt: string, path: string = snapshotPath()): void {
try {
writeFileSync(path, JSON.stringify({ ...snap, savedAt }), 'utf8')
} catch {
// disk full / permissions — the in-memory cache still works this session
}
}