Migrate active working set (last 90 days) first and verify every item — archive migration comes after active data is confirmed clean

Why This Is a Rule

Not all data is equally important. Items accessed in the last 90 days are your active working set — the notes you reference, tasks you track, and projects you're executing. These are the items that must work perfectly in the new tool because you interact with them daily. Archival data (items not accessed in 90+ days) is important but not urgent — if the archive migration has issues, you have time to fix them because you don't need those items today.

Migrating active data first and verifying it thoroughly before touching archival data serves three purposes. First, risk isolation: if the migration process has bugs, they're caught on the smaller active set (typically 10-20% of total data) before being applied to the larger archive. Second, priority alignment: the data you need immediately is available and verified in the new tool from day one. Third, motivation maintenance: successfully migrating and verifying 200 active items feels achievable and builds confidence for the larger 2,000-item archive migration.

The "verify every item" requirement for the active set is deliberately thorough because these are the items you'll interact with immediately. Any migration error in an active item will cause immediate friction. Archive items can tolerate a lower verification standard (spot-check) because you won't encounter the errors until you retrieve the item months later — and by then you can fix individually.

When This Fires

• After Test migration before committing: import 20-50 representative items and check every one for formatting, metadata, and link integrity's import test passes and Run old and new tools in parallel for 2-4 weeks during migration — new data to new tool, old data from old tool, end only when daily needs are confirmed's parallel period confirms daily needs
• When beginning the actual data migration between tools
• When the total data volume makes all-at-once migration impractical
• Complements Run old and new tools in parallel for 2-4 weeks during migration — new data to new tool, old data from old tool, end only when daily needs are confirmed (parallel validation) and Test migration before committing: import 20-50 representative items and check every one for formatting, metadata, and link integrity (import testing) with the migration execution strategy

Common Failure Mode

All-at-once migration: migrating 3,000 items simultaneously, verifying none, and discovering problems only when you try to use specific items. The active items you need today have unfixed formatting issues; the archival items you won't need for months were migrated with the same thoroughness as the urgent ones.

The Protocol

(1) Define your active working set: all items accessed or modified in the last 90 days. Most tools provide "recently modified" views. (2) Migrate only these active items to the new tool. (3) Verify every active item against the original: formatting, metadata, links (Test migration before committing: import 20-50 representative items and check every one for formatting, metadata, and link integrity's three dimensions). Fix any issues immediately. (4) Use the new tool for daily work with the verified active set. Confirm it works in practice over 1-2 weeks. (5) After active set is confirmed clean, migrate archival data in batches. Spot-check (10-20% verification) rather than full verification. Archive items that fail the spot-check get flagged for individual repair when accessed.