Versions

Every Publish in memo creates a new immutable row in memo.versions and a fresh <userId>/<projectId>/<versionId>/ prefix in R2. Versions are content-addressed by that ID and never overwritten. projects.current_version_id points at whichever version the editor preview and new-link defaults reflect; rolling forward or back just flips that pointer.

What rollback does (and doesn't) do#

• Does: change projects.current_version_id to the chosen version, bump updated_at, fire version.rollback webhook + audit row.
• Does NOT: touch existing access links. Every links row stores its version_id at create time; that's the exact version the visitor sees. Rollback only affects the editor preview and what new links default to.

This is the single most important property of memo's publishing model: shareable URLs are permanent against the version they were minted on. You can experiment freely in the editor, roll forward, roll back, roll forward again — every link out in the world stays bound to whatever you published when you sent it.

If you do want a link to start pointing at a different version, delete it and create a new one with the new version_id (UI + MCP both support this).

Surfaces#

File-level diff#

diff_versions (MCP tool) returns a four-way categorisation between any two versions of the same project:

{
  "added":     [{ "path": "hero.tsx", "sha256": "…", "size": 1280 }],
  "removed":   [{ "path": "old-cta.html", "sha256": "…", "size": 540 }],
  "changed":   [{ "path": "app.ts", "fromSha256": "…", "toSha256": "…", "fromSize": 820, "toSize": 911 }],
  "unchanged": [{ "path": "favicon.svg", "sha256": "…" }]
}

Both UI and MCP clients can stream read_version_file for any pair of files to do a unified-diff render — memo deliberately doesn't ship its own diff algorithm so clients are free to use whatever they prefer (Monaco diff, diff package, claude-rendered prose, etc.).

Audit + events#

Every rollback emits:

• audit_logs row: action="version.rollback", target_id=<versionId>, meta={ projectId, from, to, versionNumber }.
• A version.rollback webhook to every subscribed endpoint.

The webhook payload looks like:

{
  "event": "version.rollback",
  "ts": "2026-...",
  "data": {
    "projectId": "uuid",
    "versionId": "uuid",
    "from":      "uuid (or null)"
  }
}

When you'd use rollback#

• Bad publish. Compile succeeded, but the actual content turned out broken at the page level. Roll back; new links default to the prior good version; existing links you'd already sent against the broken version need to be re-created.
• A/B testing. Publish a variant, mint a new link against it, hand it out. Roll forward / back at will — the original audience's link is unaffected.
• Forensic recovery. A file got accidentally deleted via the editor or MCP. The version it was in still exists on R2 and in memo.files; rolling back surfaces it again.