Specifies the curated per-cell classification (clean /
lossy / incompatible) for column type changes, the static
transformer matrix (numeric chains, text↔structured types,
always-clean stringifications), and the PK / shortid /
uniqueness-bearing handling. Replaces the B2/C2
placeholder of "rely on engine STRICT and surface its
errors" with a learner-friendly model that:
* refuses incompatibles up-front,
* refuses lossy conversions by default with a re-run-with-
--force-conversion hint,
* refines the PK refusal: an inbound-FK PK is only refused
when the new type would change the FK target type
(so `serial → int` and `shortid → text` on FK-referenced
PKs are allowed; `int → text` etc. still refuse),
* adds a post-transformation uniqueness check for PK and
shortid columns,
* uses the pretty-table renderer (ADR-0016) for all
diagnostic row lists,
* emits a `[client-side] …` note in the success summary
whenever the transformer rewrote any cell.
`--force-conversion` accepts loss; `--dont-convert` skips
the client-side layer entirely; mutually exclusive.
Forward-look: a future iteration may add resolution flags
(`--default 0`, `--on-incompatible '<value>'`).
Also amends ADR-0002 with a new "User-facing posture"
section cementing that the database engine choice is an
implementation detail and is never named in user-visible
strings. Adds a corresponding bullet to CLAUDE.md's
working-style rules so every session picks it up.
Implementation lands as a follow-up.
claude@clouddev1
c3e5f9014f