[plainprogrammer]

Implements spec 038 (v0.2.0) per its plan: each account stores the currency its prices paid are shown in. COLLECTOR_CURRENCY becomes only the currency a new account starts with. A collector changes theirs on a Currency page linked from More and the account menu. The export writes the account's currency (format version 3 unchanged), and applying an import brings the file's currency in.

What each phase did

Phase 1, the data layer.

• accounts.currency is NOT NULL, default USD, added without a DDL transaction so its rollback copies the table with foreign keys off.
• A data migration carries the instance's COLLECTOR_CURRENCY to every account. It checks the value against an inline list of the 20 codes, writes it with one bound UPDATE, and raises on an unsupported code.
• Account defaults the column to x.default_currency, validates it ("Choose one of the listed currencies.") and adds #currency_unit.
• The export writes accounts.currency.
• The format document marks accounts "Exported" in its Coverage table and updates its prose. No schema, example or version changed.

Phase 2, every reader moves.

• 2a: lot_price (card page, collection table, and through lot_line the Move copies and location-refusal pages) and the lot form's label and prefix read Current.account.currency_unit. import_lot_line takes currency:: the account's for a removed lot, the file's for a problem row.
• 2b, the import:
  • A well-formed code outside the 20 is refused as unsupported_currency, replacing other_currency.
  • The plan gains currency_change, which counts against "nothing to change". Its two codes join the fingerprint only when there is a change, so other plans keep their old fingerprint.
  • replan reloads the account inside the apply's transaction, and the apply writes the currency first in that transaction.
  • The notice ends "; prices now shown in EUR". The preview's Profile section says "Your prices would be shown in EUR instead of USD. Nothing is converted."
  • The round trip applies every valid example (versions 1–3), whatever currency it carries.
• 2c: x.currency is removed. spec/currency_reads_spec.rb fails on any read of x.currency or x.default_currency outside Account and the initializer.

Phase 3, the Currency page.

• /currency/edit has one native select of the 20 codes (EUR — €), with a hint saying that changing converts nothing and how many lots have a price.
• PATCH /currency accepts only account[currency] via params.expect. It redirects to More (303) with "Prices are now shown in EUR.", or re-renders 422 with a field error.
• The page is plain HTML with no Stimulus. More lists Currency after Locations; the desktop account menu lists it after Import collection.

Phase 4, upgrade, backup and documents.

• script/upgrade/seeds/next.rb puts Grace in EUR (AC-4.7).
• A backup restore keeps each account's currency (AC-7.1).
• Updated: the collection-and-lots and data-portability area docs, the north star's breach note (closed), the roadmap's Store currency per account #64 line, the README, compose.yaml and config/deploy.yml comments.
• The specs index records the supersessions in both directions.

Rulings and deviations (each also in its commit body)

• The Coverage rows landed with the column (phase 1's first commit) so every commit stays green.
• 2b's refuse/plan/apply landed as one commit: removing other_currency alone would preview a EUR file as "nothing to change".
• The Currency page's two sentences are the field's c-field__hint, tied by aria-describedby, as the import page's is. There is no new CSS or pattern doc; MorePage.md gains the Currency row.
• Collector::Currency.fetch! takes setting:, so a bad stored code blames accounts.currency, not the environment variable (review m2).
• After a refused code, the controller clears the record's errors once it has copied the messages. Rails' .field_with_errors wrapper narrowed the select. This was found in the screenshots and fixed tests first (lesson in docs/lessons/).
• A one-commit bridge (68f9bee) set the round trip's account currency between phases 1 and 2b; 2b replaced it.
• Commit trailers: the first seven commits (a684f56–68f9bee) carry Co-Authored-By: Claude Sonnet 5.5 by mistake. The session runs on Opus 5.5, and every later commit carries the Opus trailer. They are not rewritten (no force-push).

Tests

• 59 examples added, 5 rewritten away (the instance-currency stubs and other_currency).
• Local bin/ci passed on 5847f25: 2471 examples, 0 failures, 1 pending.
• The pre-push bin/ci on f6bd0f7 passed on the second attempt. The first ran 2474 examples, and its one failure was the known cross-worktree harness tmpdir flake (Flaky: Upgrade::Harness "removes its temporary directory" races other suites through the shared tmpdir #178).

Implementation review

SPEC-ALIGNED WITH MINOR GAPS (sdd-review Mode B, read-only, Opus). Nothing was blocking. Every AC was met; AC-4.6 is met by CI's upgrade proof only, and AC-3.4 by the unit test plus reading.

• Major: verification.md was missing. It is written.
• Minors:
  • MorePage doc: fixed.
  • fetch!'s error naming the environment variable: fixed.
  • AC-6.7's rendered sentence: now asserted.
  • xyz: now tested.
  • AC-4.3's second clause: recorded as proved by structure.
  • The local Gemfile.lock arm64 noise: left uncommitted.

Details per AC are in verification.md.

Screenshots

Captured in headless Firefox against this worktree's dev server, seeded by a scratch script with one collector, four printings and three priced lots. The tiles have no card art.

Walkthrough: the table in $, More → Currency → EUR → Save, the notice, the table in €, the lot form (EUR) / €, and an import preview of a USD file ("Your prices would be shown in USD instead of EUR", removed lots in €).

Desktop, light	Desktop, dark

Phone (390px), light	Phone (390px), dark	More on a phone

A refused code (422), and the import preview in full:

For the maintainer to check by hand

• AC-4.6: CI's bin/upgrade-smoke, on both architectures, must stay green. spec/backup_upgrade_spec.rb rolls back STEP=1, which is now the empty data step, so it no longer exercises a schema rollback. The migration spec covers the column's rollback. Consider STEP=2 there.
• Your copies on a card page: open one in a non-USD account and check a price in the select's symbol style (CHF — CHF, kr). Those repeats are accepted by decision 8.
• Stored previews at deploy: one made before the deploy, whose file's currency differs from the account's, shows as stale once and needs previewing again (an accepted risk in the plan).

Closes #64

🤖 Generated with Claude Code

[plainprogrammer]

Follow-ups filed by the coordinator: #179 (backup_upgrade_spec's STEP=1 now rolls back only the empty data step), #180 (field_with_errors wrappers on other forms' 422s), and #178 (harness tmpdir race hit by the pre-push run).