patrickz
Before you start
A coding agent, browser and three fictional journal entries.
Why this lesson exists
The original offline-first personal tracker starts with one record type in IndexedDB and adds export before sync; accounts, cloud tables and conflict rules come later. This lab stops at an export and import you have tested.
Do the exercise
Set your boundary
Start with one record type, stable identifiers and local storage. Implement export before adding cloud synchronization.
Choose one record type
Choose one record type, such as a journal entry, with a stable ID and created and updated timestamps.
Save it with IndexedDB
Save and query it with IndexedDB.
Add export and import
Add a JSON export and an import that keeps the same IDs, before any sync.
Next sessions, not today
- Module registry Add a module registry so features can be enabled independently.
- Threat-model first Before adding accounts, threat-model where secrets could leak and how one user could reach another user’s records.
- Accounts and cloud tables Add authentication and per-user cloud tables.
- Sync conflicts Resolve sync conflicts with timestamps and visible status.
A prompt to adapt
Replace the bracketed parts with your own details.
Help me build an offline-first tracker in [TypeScript or JavaScript] in a new practice folder. First version only: one record type, [journal entries], with stable IDs and local storage, and export before any sync. No module registry, accounts, cloud tables or sync conflict rules yet, and no API secrets in client code. List the setup commands before changing any files. Then work in three checkpoints and, after each, tell me how to check it: 1. A data contract with a stable ID, created and updated timestamps and a deletion marker, shown as a TypeScript type. 2. Saving and querying records with IndexedDB, using the indexes you choose. 3. A JSON export and an import that keep the same IDs, plus a test that exports three entries, clears the store, imports them and compares every field.
Once it runs, paste your code and ask:
Review this local tracker for data loss. List every way a reload, a failed or repeated import, or an edit made offline could discard or duplicate an entry, and the test that would catch each one.
Run this experiment
Create three entries, reload, export them, remove only the disposable test copy and import into a fresh practice profile. Compare fields and identifiers.
Check your result
Use evidence from your output. A confident explanation from the AI is not enough.
If it isn’t working
Do not add synchronization until conflict rules are explicit. Never embed production API secrets in client code.
Optional. Progress stays in this browser.
Where this came from
Public project repository ↗. The practice lesson is an adaptation, not a verbatim transcript. About the sources.
Prepared September 2026. Tools and interfaces change; use current official setup instructions. Session lengths are estimates.