Migration Day Runbook Skill

File migrations fail at the edges, not the middle: work edited during the copy window (lost or forked), permissions that mapped wrong (the intern sees the comp sheet; Legal sees nothing), links across the company now pointing at a dead platform, and an old system left writable so half the team never leaves. The runbook handles the edges: a short announced freeze, copy with verification (counts and spot-checks, not vibes), a permissions remap done as its own workstream, cutover comms with the three answers everyone needs, and the old platform flipped read-only — the single move that makes migrations stick.

What This Skill Produces

• The runbook — phased: prepare → freeze → copy → verify → permissions → cutover → afterlife, each with owner and duration
• The verification plan — counts by folder, spot-restores, and the biggest-risk samples checked by hand
• The permissions remap — old-model groups/shares → new-model equivalents, with the deny-by-default posture for mismatches
• The comms set — the advance notice, the freeze reminder, and the cutover announcement with its three answers

Required Inputs

Ask for these if not provided:

• From → to, and the size — platforms, volume (GB and file count), and any known exotica (huge files, weird formats, apps writing into the old drive)
• The sharing surface — external shares, published links, and integrations pointing at the old platform; each is a breakage waiting for its line in the runbook
• The freeze tolerance — can the team stop editing for a day? A weekend? Never (then the delta-sync approach, stated)?
• The permission model gap — how sharing works old vs. new; the remap is where migrations quietly leak confidential files

Framework: The Edge Rules

1. Freeze short, announce twice: the copy happens inside a declared no-edits window (evening/weekend for most teams) — announced a week out and the day before. Edits during the copy are the classic loss; the freeze is cheaper than the fork-hunt.
2. Verify by count and by sample: post-copy: file counts per top-level folder old-vs-new, total size within tolerance, and hand-checks of the highest-stakes folders (Legal, Finance, the current projects). A migration is "done" when verification says so, not when the progress bar does.
3. Permissions are a workstream, not a checkbox: inventory the old platform's shares (especially external ones), map to the new model, and where the models don't align, fail closed — over-restricting gets a complaint ticket; over-sharing gets an incident. External shares get re-issued deliberately, not bulk-recreated.
4. The cutover announcement answers exactly three questions: where do I go now (the link) · what happened to my stuff (same structure, here's the map) · what do I do if something's missing (the named person, the SLA). Everything else is noise; these three prevent the help-desk flood.
5. The old platform goes read-only, immediately: the afterlife rule — readable for the transition period (comfort + the missing-file safety net), writable never (or half the team quietly stays). A read-only banner pointing at the new home does more for adoption than any training session. Decommission date set now, calendar-reminded, executed after the retention check (document-retention-map).

Output Format

Migration Runbook: old] → new], date]

Phases

| Phase | When | Owner | Duration | |---|---|---|---| Prepare (inventory, permissions map, comms 1) · Freeze · Copy · Verify · Permissions · Cutover (comms 3) · Afterlife (read-only flip)]

Verification Plan

Counts per top folder · size tolerance · the hand-check list (highest-stakes folders) · the pass/fail line]

Permissions Remap

Old shares inventory → new equivalents · fail-closed mismatches · external shares re-issued deliberately]

Comms

T-7 notice · T-1 freeze reminder · cutover announcement: the three answers + the missing-file contact]

Rollback Line

The condition that aborts (verification fails, permissions can't map) · rollback = unfreeze the old, reschedule — cheap because the old is untouched until read-only]

Quality Checks

• ] The copy happens inside an announced freeze
• ] Verification is counts + samples with a pass/fail line, before cutover comms
• ] Permission mismatches fail closed, external shares handled by hand
• ] The announcement answers exactly the three questions with a named missing-file contact
• ] The old platform is read-only from cutover, with a decommission date set

Anti-Patterns

• ] Do not copy a live drive — the freeze is one evening; the fork-hunt is one month
• ] Do not trust the progress bar as verification — counts and samples or it didn't happen
• ] Do not bulk-recreate external shares — each one re-issued is each one re-decided
• ] Do not leave the old platform writable "during transition" — that's two sources of truth, i.e., zero
• ] Do not skip the rollback line — a migration that can't abort will be pushed through broken