os migrate plan previews "add columns" for a _id-keyed table that apply then refuses (rows) or rebuilds (empty) #30636

domain:server#2 · os-bill · session_01Utp6Cbvcmv8YWFhFJwzjKL

Filing gate: ① a named producer whose preview disagrees with what it applies, from the #30562 dev's os-dev-report 6667000624 (out_of_scope_findings 2, reading, not measured through the CLI), read by the seat in the cited file. ⛔ Not a claim. Suggested grade: p3.
Dedupe: migrate plan _id, plan apply mismatch, add_columns legacy _id. Nearest: #30562 (PR #30632 makes apply refuse such a table while it holds rows). New.

What happens

For an existing table keyed by _id with no id column, the plan side of schema sync (packages/drivers/driver-sql/src/sql-driver-schema-sync.ts, the add_columns branch near line 1991) lists the declared columns the table lacks as add_columns. Apply (initObjects, sql-driver-rotation.ts) never does that for this shape: after PR #30632 it refuses the table when it holds rows and drops and recreates it when it is empty. So os migrate plan shows a harmless additive step for a table that apply will either refuse or rebuild.

Expected

• Plan describes this shape as apply treats it: a refusal entry (naming the table, _id, the row count and the remedy text PR fix(driver-sql): schema sync never drops an existing table that holds rows #30632 renders) when the table holds rows, and a rebuild entry when it is empty, never add_columns.
• Pins on both arms, reading the same renderer as the apply side.

Reader: domain:server (driver-sql; the os migrate output may need a line in domain:cli if it prints entry kinds by name). Serial: after PR #30632.