Prevent sole admin from deleting their account

Without this guard, the last admin in the system could delete their own
account, making the application unmanageable. This adds a model method
`User#sole_admin?`, a controller guard in `RegistrationsController#destroy`,
and disables the delete button in the profile edit view when the current
user is the only remaining admin.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -1,84 +0,0 @@
-# CLAUDE.md
-
-This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
-
-## Project Overview
-
-Fixin.me is a "quantified self" Rails 7.2.3 application for personal data tracking. Users define hierarchical **quantities** (metrics to track), **units** (with optional conversion hierarchies), and **readouts** (individual measurements). There is also a non-persistent **measurement** model used as a form wrapper.
-
-## Setup
-
-Configuration files are distributed as `.dist` templates — copy and customize before use:
-
-```bash
-cp config/application.rb.dist config/application.rb
-cp config/database.yml.dist config/database.yml
-cp config/puma.rb.dist config/puma.rb
-```
-
-```bash
-bundle config --local frozen true
-bundle config --local path .gem
-bundle config --local with mysql development test   # or: pg, sqlite
-bundle install
-RAILS_ENV=development bundle exec rails db:create db:migrate db:seed
-```
-
-## Common Commands
-
-```bash
-bundle exec rails s                                          # start server
-bundle exec rails test                                       # all unit/model/controller tests
-bundle exec rails test:system                                # all system tests (Capybara + Selenium)
-bundle exec rails test test/system/units_test.rb            # single test file
-bundle exec rails test --seed 64690 --name test_add_unit    # single test by name
-bundle exec rails db:seed:export                             # export default settings as seed file
-```
-
-## Architecture
-
-### Data Model
-
-- **Quantity** — hierarchical tree (self-referential `parent_id`). Cached `depth` and `pathname` fields are recomputed via recursive CTEs on write. Direct assignment to cached fields is blocked.
-- **Unit** — optional hierarchy via `base_id` and `multiplier` for unit conversion. Multiplier precision/scale is validated by a custom validator.
-- **Readout** — single measurement: `value` (IEEE 754 float), `quantity`, `unit`, `category`.
-- **Measurement** — `ActiveModel::Model` form wrapper (not database-backed); bridges the readout creation form.
-- **User** — Devise-managed with a status enum: `admin`, `active`, `restricted`, `locked`, `disabled`. Admins can disguise as other users.
-
-### Hierarchical Queries
-
-Both `Quantity` and `Unit` use recursive CTEs for tree traversal (ordered traversal, ancestors, progenies, common ancestors). `lib/core_ext/arel/` patches Arel to support CTE with `UPDATE`/`DELETE` statements, working around Rails issue #54658.
-
-### Custom Extensions (`lib/core_ext/`)
-
-- **arel/** — CTE support for UPDATE/DELETE
-- **active_model/** — precision/scale validator used by `Unit#multiplier`
-- **active_record/** — `attr_cached` mechanism (see `ApplicationRecord`)
-- **action_view/** — record identifier suffixes
-- Miscellaneous: `Array#delete_bang`, `BigDecimal` scientific notation
-
-### Response Handling
-
-Controllers respond to both HTML and Turbo Stream formats. Errors during Turbo Stream requests trigger a redirect with flash rather than rendering inline, handled in `ApplicationController`.
-
-### Numeric Precision
-
-Readout values are stored as IEEE 754 double-precision floats (not fixed-point decimals). Rationale in `DESIGN.md`: biological values span many orders of magnitude; 15-digit float precision is sufficient and avoids conversion overhead.
-
-### Routes
-
-```
-measurements   GET/POST /measurements
-readouts       GET/POST /readouts, DELETE /readouts/:id/discard
-quantities     CRUD + POST /quantities/:id/reparent
-units          CRUD + POST /units/:id/rebase
-users          CRUD + POST /users/:id/disguise, POST /users/revert
-default/       namespace for default units import/export and admin panel
-root           → /units (authenticated), /sign_in (unauthenticated)
-```
-
-## Database Requirements
-
-The database must support:
-- Recursive CTEs with `UPDATE`/`DELETE` (MySQL ≥ 8.0, PostgreSQL, or SQLite3)
-- Decimal precision of 30+ digits

DESIGN.md

@@ -1,34 +0,0 @@
-DESIGN
-======
-
-Below is a list of design decisions. The justification is to be consulted
-whenever a change is considered, to avoid regressions.
-
-### Data type for DB storage of numeric values (`decimal` vs `float`)
-
-* among database engines supported (by Rails), SQLite offers storage of
-  `decimal` data type with the lowest precision, equal to the precision of
-  `REAL` type (double precision float value, IEEE 754), but in a floating point
-  format,
-    * decimal types in other database engines offer greater precision, but store
-      data in a fixed point format,
-* biology-related values differ by several orders of magnitude; storing them in
-  fixed point format would only make sense if required precision would be
-  greater than that offered by floating point format,
-    * even then, fixed point would mean either bigger memory requirements or
-      worse precision for numbers close to scale limit,
-        * for a fixed point format to use the same 8 bytes of storage as IEEE
-          754, precision would need to be limited to 18 digits (4 bytes/9 digits)
-          and scale approximately half of that - 9,
-    * double precision floating point guarantees 15 digits of precision, which
-      is more than enough for all expected use cases,
-        * single precision floating point only guarntees 6 digits of precision,
-          which is estimated to be too low for some use cases (e.g. storing
-          latitude/longitude with a resolution grater than 100m)
-* double precision floating point (IEEE 754) is a standard that ensures
-  compatibility with all database engines,
-    * the same data format is used internally by Ruby as a `Float`; it
-      guarantees no conversions between storage and computation,
-    * as a standard with hardware implementations ensures both: computing
-      efficiency and hardware/3rd party library compatibility as opposed to Ruby
-      custom `BigDecimal` type

app/assets/images/pictograms/alert-outline.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M12,2L1,21H23M12,6L19.53,19H4.47M11,10V14H13V10M11,16V18H13V16" /></svg>
+<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path fill="#ffffff" d="M12,2L1,21H23M12,6L19.53,19H4.47M11,10V14H13V10M11,16V18H13V16" /></svg>

app/assets/images/pictograms/check-circle-outline.svg

@@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M12 2C6.5 2 2 6.5 2 12S6.5 22 12 22 22 17.5 22 12 17.5 2 12 2M12 20C7.59 20 4 16.41 4 12S7.59 4 12 4 20 7.59 20 12 16.41 20 12 20M16.59 7.58L10 14.17L7.41 11.59L6 13L10 17L18 9L16.59 7.58Z" /></svg>
+<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path fill="#ffffff" d="M12 2C6.5 2 2 6.5 2 12S6.5 22 12 22 22 17.5 22 12 17.5 2 12 2M12 20C7.59 20 4 16.41 4 12S7.59 4 12 4 20 7.59 20 12 16.41 20 12 20M16.59 7.58L10 14.17L7.41 11.59L6 13L10 17L18 9L16.59 7.58Z" /></svg>

app/assets/images/pictograms/view-columns.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M4,4H8V20H4V4M10,4H14V20H10V4M16,4H21V20H16V4Z"/></svg>

app/assets/images/pictograms/view-rows.svg

@@ -1 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" id="icon" viewBox="0 0 24 24"><path d="M3,5H21V7H3V5M3,11H21V13H3V11M3,17H21V19H3V17Z"/></svg>

app/assets/stylesheets/application.css

@@ -18,12 +18,10 @@
 /* Strive for simplicity:
  * * style elements/tags only - if possible,
  * * replace element/tag name with class name - if element has to be styled
- * differently depending on context (e.g. <form>, <table>, <a> as link/button),
- * * styles with multiple selectors should have all selectors with same
- * specificity, to allow proper rule specificity vs order management.
+ * differently depending on context (e.g. form)
  *
- * NOTE: style in a modular way, similar to how CSS @scope would be used,
- * to make transition easier once @scope is widely available. */
+ * NOTE: Style in a modular way, similar to how CSS @scope would be used,
+ * to make transition easier once @scope is widely available */
 :root {
   --color-focus-gray: #f3f3f3;
   --color-border-gray: #dddddd;
@@ -36,7 +34,6 @@
   --color-blue: #009ade;
   --color-dark-red: #b21237;
   --color-red: #ff1f5b;
-  --color-purple: #8b2be2;
 
   --depth: 0;
 
@@ -56,36 +53,17 @@
 :focus-visible {
   outline: none;
 }
-/* NOTE: move to higher priority layer instead of using !important?; add CSS
- * @layer requirements in README */
-[disabled] {
-  border-color: var(--color-border-gray) !important;
-  color: var(--color-border-gray) !important;
-  /* NOTE: cannot set cursor when `pointer-events: none`; can be fixed by setting
-   * `cursor` on wrapping element.
-  cursor: not-allowed; */
-  fill: var(--color-border-gray) !important;
-  pointer-events: none !important;
-}
-/* Styles set `display` without distinguishing between [hidden] elements, making
- * them visible. */
-[hidden] {
-  display: none !important;
-}
 
 
 /* Color coding of input controls' background:
- *  blue - target for interaction with pointer,
- *  gray - target for interaction with keyboard,
- *  red - destructive, non-undoable action.
+ *  blue - target for interaction with pointer
+ *  gray - target for interaction with keyboard
+ *  red - destructive, non-undoable action
  */
-/* TODO: merge selectors using :is() */
-a,
 button,
 details,
 input,
 select,
-summary,
 textarea {
   background-color: inherit;
   font: inherit;
@@ -95,29 +73,56 @@ input,
 select {
   text-align: inherit;
 }
+a,
+button,
+input[type=submit] {
+  cursor: pointer;
+  text-decoration: none;
+  white-space: nowrap;
+}
+/* [hidden] submit controls cannot have `display` set as it makes them visible */
+.button,
+button:not([hidden]),
+input[type=submit]:not([hidden]),
+.tab {
+  align-items: center;
+  color: var(--color-gray);
+  display: flex;
+  fill: var(--color-gray);
+  font-weight: bold;
+}
+.button,
+button,
+input[type=submit] {
+  font-size: 0.8rem;
+  padding: 0.6em 0.5em;
+  width: fit-content;
+}
+input:not([type=submit]):not([type=checkbox]),
+select,
+summary,
+textarea {
+  padding: 0.2em 0.4em;
+}
+.button,
+button,
 input,
 select,
 summary,
 textarea {
-  border: 1px solid var(--color-gray);
+  border: solid 1px var(--color-gray);
   border-radius: 0.25em;
-  padding: 0.2em 0.4em;
 }
-svg {
-  height: 1.4em;
-  margin: 0 0.2em 0 0;
-  width: 1.4em;
-}
-svg:last-child {
-  margin-right: 0;
-}
-.chart-panel svg {
-  height: auto;
-  margin: 0;
-  width: auto;
+[name=cancel],
+.auxiliary {
+  border-color: var(--color-border-gray);
+  color: var(--color-nav-gray);
+  fill: var(--color-nav-gray);
 }
+input[type=checkbox],
+svg,
 textarea {
-  margin: 0;
+  margin: 0
 }
 input[type=checkbox] {
   accent-color: var(--color-blue);
@@ -125,20 +130,17 @@ input[type=checkbox] {
   -webkit-appearance: none;
   display: flex;
   height: 1.1em;
-  margin: 0;
-  padding: 0;
   width: 1.1em;
 }
 input[type=checkbox]:checked {
   appearance: checkbox;
   -webkit-appearance: checkbox;
 }
-/* Hide spin buttons of <input type=number>. */
-/* TODO: add spin buttons inside <input type=number>: before (-) and after (+) input. */
+/* Hide spin buttons in input number fields */
+/* TODO: add spin buttons inside input[number]: before (-) and after (+) input */
 input[type=number] {
   appearance: textfield;
   -moz-appearance: textfield;
-  text-align: end;
 }
 input::-webkit-inner-spin-button {
   -webkit-appearance: none;
@@ -147,112 +149,37 @@ input::-webkit-outer-spin-button {
   -webkit-appearance: none;
   margin: 0;
 }
-/* Text color of table form controls:
- *  - black for row/table forms,
- *  - inherited for internal (column specific) buttons/forms. */
-table input,
-table select,
-table summary,
-table textarea {
-  border-color: var(--color-border-gray);
+.button > svg,
+.tab > svg,
+button > svg {
+  height: 1.4em;
+  width: 1.4em;
 }
-table input,
-table select,
-table textarea {
-  padding-block: 0.375em;
+.button > svg:not(:last-child),
+.tab > svg:not(:last-child),
+button > svg:not(:last-child) {
+  margin-right: 0.2em;
 }
-table form input,
-table form select,
-table form summary,
-table form textarea {
-  color: inherit;
-}
-table svg:not(:only-child) {
-  height: 1.25em;
-  width: 1.25em;
+/* TODO: move normal non-button links (<a>:hover/:focus) styling here (i.e.
+ * page-wide, top-level) and remove from table.items - as the style should be
+ * same everywhere */
+.button:focus-visible,
+button:focus-visible,
+input[type=submit]:focus-visible {
+  background-color: var(--color-focus-gray);
 }
 input:focus-visible,
 select:focus-visible,
 select:focus-within,
-/* TODO: how to achieve `summary:focus-within` for `::details-content`? */
+/* TODO: how to achieve summary:focus-within for ::details-content? */
 summary:focus-visible,
 textarea:focus-visible {
   accent-color: var(--color-dark-blue);
   background-color: var(--color-focus-gray);
-  color: black;
 }
-input:hover,
-select:hover,
-summary:hover,
-textarea:hover {
-  border-color: var(--color-blue);
-  outline: 1px solid var(--color-blue);
-}
-select:hover,
-summary:hover {
-  color: black;
-  cursor: pointer;
-}
-/* TODO: style <details>/<summary> focus to match <select> as much as possible.
-summary:focus-visible::before,
-summary:hover::before {
-  background-color: black;
-}
- */
-input:invalid,
-select:invalid,
-textarea:invalid {
-  border-color: var(--color-red);
-  outline-color: var(--color-red);
-}
-
-/* `.button`: button-styled <a>, <button>, <input type=submit>.
- * `.link`: any other <a>.
- * `.tab`: tab-styled <a>.
- */
-.button,
-.link,
-.tab {
-  cursor: pointer;
-  text-decoration: none;
-  white-space: nowrap;
-}
-.button,
-.tab {
-  align-items: center;
-  color: var(--color-gray);
-  display: flex;
-  fill: var(--color-gray);
-  font-weight: bold;
-}
-.button {
-  border: 1px solid var(--color-gray);
-  border-radius: 0.25em;
-  font-size: 0.8rem;
-  padding: 0.6em 0.5em;
-  width: fit-content;
-}
-.link {
-  color: inherit;
-  text-decoration: underline 1px var(--color-border-gray);
-  text-underline-offset: 0.25em;
-}
-button.link {
-  border: none;
-  padding: 0;
-}
-[name=cancel],
-.auxiliary {
-  border-color: var(--color-border-gray);
-  color: var(--color-nav-gray);
-  fill: var(--color-nav-gray);
-}
-.button:focus-visible,
-.tab:focus-visible,
-.tab:hover {
-  background-color: var(--color-focus-gray);
-}
-.button:hover {
+.button:hover,
+button:hover,
+input[type=submit]:hover {
   background-color: var(--color-blue);
   border-color: var(--color-blue);
   color: white;
@@ -262,31 +189,32 @@ button.link {
   background-color: var(--color-red);
   border-color: var(--color-red);
 }
-tr:has(select[data-changed]) button[name="button"],
-.set-default-unit:not([disabled]) {
-  background-color: var(--color-purple);
-  border-color: var(--color-purple);
-  color: white;
-  fill: white;
+input:hover,
+select:hover,
+summary:hover,
+textarea:hover {
+  border-color: var(--color-blue);
+  outline: solid 1px var(--color-blue);
 }
-.link:focus-visible {
-  text-decoration-color: var(--color-gray);
+select:hover,
+summary:hover {
+  cursor: pointer;
 }
-.link:hover {
-  color: var(--color-blue);
-  text-decoration-color: var(--color-blue);
+input:invalid,
+select:invalid,
+textarea:invalid {
+  border-color: var(--color-red);
+  outline: solid 1px var(--color-red);
 }
-table .button {
-  border-color: var(--color-border-gray);
-  color: var(--color-table-gray);
-  font-weight: normal;
-  height: 100%;
-  padding: 0.4em;
+input[type=text]:read-only,
+textarea:read-only {
+  border: none;
+  padding-inline: 0;
 }
 
 
-/* NOTE: collapse gaps around empty rows (`topside`) once possible with
- * `grid-collapse` property and remove alternative `grid-template-areas`.
+/* NOTE: collapse gaps around empty rows (`topside`) once possible
+ * with grid-collapse property and remove alternative grid-template
  * https://github.com/w3c/csswg-drafts/issues/5813 */
 body {
   display: grid;
@@ -294,16 +222,16 @@ body {
   grid-template-areas:
     "header    header  header"
     "nav       nav     nav"
+    "leftside  topside rightside"
     "leftside  main    rightside";
   grid-template-columns: 1fr minmax(max-content, 2fr) 1fr;
   font-family: system-ui;
   margin: 0.4em;
 }
-body:has(> .topside-area) {
+body:not(:has(.topside-area)) {
   grid-template-areas:
     "header    header  header"
     "nav       nav     nav"
-    "leftside  topside rightside"
     "leftside  main    rightside";
 }
 
@@ -319,14 +247,18 @@ header {
   margin-inline-start: 4%;
 }
 .navigation > .tab {
-  border-bottom: 2px solid var(--color-nav-gray);
+  border-bottom: solid 2px var(--color-nav-gray);
   flex: 1;
   font-size: 1rem;
   justify-content: center;
   padding-block: 0.4em;
 }
+.navigation > .tab:hover,
+.navigation > .tab:focus-visible {
+  background-color: var(--color-focus-gray);
+}
 .navigation > .tab.active {
-  border-bottom: 4px solid var(--color-blue);
+  border-bottom: solid 4px var(--color-blue);
   color: var(--color-blue);
   fill: var(--color-blue);
 }
@@ -358,7 +290,7 @@ header {
 
 #flashes {
   display: grid;
-  row-gap: 0.4em;
+  gap: 0.2em;
   grid-template-columns: 1fr auto auto auto 1fr;
   left: 0;
   pointer-events: none;
@@ -374,17 +306,13 @@ header {
   display: grid;
   grid-column: 2/5;
   grid-template-columns: subgrid;
-  line-height: 2.2em;
   pointer-events: auto;
 }
-.flash:before {
-  filter: invert(100%);
-  height: 1.4em;
-  margin: 0 0.5em;
-  width: 1.4em;
-}
 .flash.alert:before {
   content: url('pictograms/alert-outline.svg');
+  height: 1.4em;
+  margin: 0 0.5em;
+  width: 1.4em;
 }
 .flash.alert {
   border-color: var(--color-red);
@@ -392,24 +320,35 @@ header {
 }
 .flash.notice:before {
   content: url('pictograms/check-circle-outline.svg');
+  height: 1.4em;
+  margin: 0 0.5em;
+  width: 1.4em;
 }
 .flash.notice {
   border-color: var(--color-blue);
   background-color: var(--color-blue);
 }
-.flash svg {
-  cursor: pointer;
-  fill: white;
-  height: 2.2em;
-  opacity: 0.6;
-  padding: 0.4em 0.5em;
-  width: 2.4em;
+.flash > div {
+  grid-column: 2;
 }
-.flash svg:hover {
+/* NOTE: currently flash button inherits some unnecessary styles from generic
+ * button. */
+.flash > button {
+  border: none;
+  color: inherit;
+  cursor: pointer;
+  font-size: 1.4em;
+  font-weight: bold;
+  grid-column: 3;
+  opacity: 0.6;
+  padding: 0.2em 0.4em;
+}
+.flash > button:hover {
   opacity: 1;
 }
 
 
+/* TODO: Hover over invalid should work like in measurements (thin vs thick border) */
 .labeled-form {
   align-items: center;
   display: grid;
@@ -426,7 +365,7 @@ header {
 .labeled-form label.required {
   font-weight: bold;
 }
-/* Don't style `label.error + input` if case already covered by `input:invalid`. */
+/* Don't style `label.error + input` if case already covered by input:invalid */
 .labeled-form label.error {
   color: var(--color-red);
 }
@@ -446,117 +385,200 @@ header {
 .labeled-form .auxiliary {
   grid-column: 3;
   /* If more buttons are needed, `grid-row` can be replaced with
-   * `reading-flow: grid-columns` to ensure proper [tabindex] order. */
+   * `reading-flow: grid-columns` to ensure proper tabindex order */
   grid-row: 1;
   height: 100%;
   padding-block: 0;
 }
 
-.tabular-form table {
-  border: none;
-  border-spacing: 0.4em 0;
-  margin-inline: -0.4em;
-}
-.tabular-form table td {
-  border: none;
-  vertical-align: middle;
-}
-.tabular-form table td {
-  padding-inline: 0;
-}
-.tabular-form table :is(form, input, select, textarea):only-child {
-  margin-inline-start: 0;
-}
 
-
-.items-table {
+/* TODO: remove .items class (?) and make 'form table' work properly */
+table.items {
   border-spacing: 0;
-  border: 1px solid var(--color-border-gray);
+  border: solid 1px var(--color-border-gray);
   border-radius: 0.25em;
   font-size: 0.85rem;
   text-align: left;
 }
-.items-table thead {
+table:not(:has(tr)) {
+  display: none;
+}
+table.items thead {
   font-size: 0.8rem;
 }
-.items-table thead,
-.items-table tbody tr:hover {
+table.items thead,
+table.items tbody tr:hover {
   background-color: var(--color-focus-gray);
 }
-.items-table th {
-  padding: 0.75em 0 0.75em 1em;
+table.items th {
+  padding-block: 0.75em;
   text-align: center;
 }
-.items-table th:last-child {
-  padding-inline-end: 0.4em;
+table.items th,
+table.items td {
+  padding-inline: 1em 0;
 }
-.items-table td {
-  border-top: 1px solid var(--color-border-gray);
-  height: 2.4em;
-  padding: 0.1em 0 0.1em calc(1em + var(--depth) * 0.8em);
-}
-.items-table td:last-child {
-  padding-inline-end: 0.1em;
-}
-.items-table :is(form, input, select, textarea):only-child {
-  margin-inline-start: calc(-0.4em - 0.9px);
-}
-/* For <a> to fill table cell completely, we use an `::after` pseudoelement. */
-/* TODO: expand to whole row? will require adjusting z-index on inputs/buttons */
-.items-table td:has(> .link) {
+/* For <a> to fill <td> completely, we use an ::after pseudoelement. */
+table.items td.link {
+  padding: 0;
   position: relative;
 }
-.items-table .link::after {
+table.items td.link a {
+  color: inherit;
+  font: inherit;
+}
+table.items td.link a::after {
   content: '';
-  inset: -1px 0 0 0;
+  inset: 0;
   position: absolute;
 }
-.items-table .flex {
+table.items td:first-child {
+  padding-inline-start: calc(1em + var(--depth) * 0.8em);
+}
+table.items td:has(input, select, textarea) {
+  padding-inline-start: calc(0.6em - 0.9px);
+}
+table.items td:first-child:has(input, select, textarea) {
+  padding-inline-start: calc(0.6em + var(--depth) * 0.8em - 0.9px);
+}
+table.items th:last-child {
+  padding-inline-end: 0.4em;
+}
+table.items td:last-child {
+  padding-inline-end: 0.1em;
+}
+table.items td {
+  border-top: solid 1px var(--color-border-gray);
+  height: 2.4em;
+  padding-block: 0.1em;
+}
+table.items .actions {
+  display: flex;
   gap: 0.4em;
   justify-content: end;
 }
-.items-table .dropzone {
+table.items .actions.centered {
+  justify-content: center;
+}
+table.items tr.dropzone {
   position: relative;
 }
-.items-table .dropzone::after {
+table.items tr.dropzone::after {
   content: '';
   inset: 1px 0 0 0;
   position: absolute;
-  outline: 2px dashed var(--color-blue);
+  outline: dashed 2px var(--color-blue);
   outline-offset: -1px;
   z-index: var(--z-index-table-row-outline);
 }
-.items-table .handle {
-  cursor: grab;
+table.items td.handle {
+  cursor: move;
 }
-.items-table .form td {
-  vertical-align: middle;
+table.items tr.form td {
+  vertical-align: top;
 }
-.items-table td:not(:first-child),
+
+/* TODO: replace :hover:focus-visible combos with proper LOVE stye order */
+/* TODO: Update table styling: simplify selectors, deduplicate, remove non-font rem. */
+table.items td.link a:hover,
+table.items td.link a:focus-visible,
+table.items td.link a:hover:focus-visible {
+  text-decoration: underline;
+  text-decoration-thickness: 0.05rem;
+  text-underline-offset: 0.2rem;
+}
+table.items td.link a:hover {
+  color: var(--color-blue);
+}
+table.items td.link a:focus-visible {
+  text-decoration-color: var(--color-gray);
+}
+table.items td.link a:hover:focus-visible {
+  color: var(--color-dark-blue);
+}
+
+table.items td:not(:first-child),
 .grayed {
   color: var(--color-table-gray);
-  fill: var(--color-gray);
+  fill: var(--color-table-gray);
 }
-.items-table td:has(> svg:only-child) {
+table.items svg {
+  height: 1rem;
+  vertical-align: middle;
+  width: 1rem;
+}
+table.items svg:last-child {
+  height: 1.2rem;
+  width: 1.2rem;
+}
+table.items td.svg {
   text-align: center;
 }
+table.items td.number {
+  text-align: right;
+}
+table.items .button,
+table.items button,
+table.items input[type=submit] {
+  font-weight: normal;
+  height: 100%;
+  padding: 0.4em;
+}
+table.items input:not([type=submit]):not([type=checkbox]),
+table.items select,
+table.items textarea {
+  padding-block: 0.375em;
+}
+/* TODO: find a way (layers?) to style inputs differently while making sure
+ * hover works properly without using :not(:hover) selectors here. */
+table.items .button:not(:hover),
+table.items button:not(:hover),
+table.items input:not(:hover),
+table.items select:not(:hover),
+table.items textarea:not(:hover) {
+  border-color: var(--color-border-gray);
+}
+table.items .button:not(:hover),
+table.items button:not(:hover),
+table.items input[type=submit]:not(:hover),
+table.items select:not(:hover) {
+  color: var(--color-table-gray);
+}
+table.items select:focus-within,
+table.items select:focus-visible {
+  color: black;
+}
+form table.items {
+  border: none;
+}
+form table.items td {
+  border: none;
+  text-align: left;
+  vertical-align: middle;
+}
+form table.items td:first-child {
+  color: inherit;
+}
 
 
-.center {
+.centered {
   margin: 0 auto;
 }
+.extendedright {
+  margin-right: auto;
+}
 .hexpand {
   width: 100%;
 }
-.flex {
+.hflex {
   display: flex;
   gap: 0.8em;
 }
-.flex.reverse {
+.hflex.reverse {
   flex-direction: row-reverse;
 }
-.flex.vertical {
-  flex-direction: column;
+.hflex.centered {
+  justify-content: center;
 }
 .hint {
   color: var(--color-table-gray);
@@ -564,18 +586,21 @@ header {
   font-size: 0.9rem;
   text-align: center;
 }
-.hmin50 {
-  min-width: 50%;
+.vflex {
+  display: flex;
+  gap: 0.8em;
+  flex-direction: column;
 }
-.italic {
-  color: var(--color-gray);
-  font-style: italic;
-}
-.ralign {
-  text-align: right;
-}
-.rextend {
-  margin-right: auto;
+[disabled] {
+/* label:has(input[disabled]) {
+ * TODO: disabled checkbox blue square focus removal; disabled label styling;
+ * focused label styling (currently only checkbox has focus)
+ * */
+  border-color: var(--color-border-gray) !important;
+  color: var(--color-border-gray) !important;
+  cursor: not-allowed;
+  fill: var(--color-border-gray) !important;
+  pointer-events: none;
 }
 
 
@@ -587,12 +612,12 @@ summary {
   align-items: center;
   color: var(--color-gray);
   display: flex;
-  gap: 0.4em;
+  gap: 0.2em;
   height: 100%;
   white-space: nowrap;
 }
 summary::before {
-  background-color: currentColor;
+  background-color: #000;
   content: "";
   height: 1em;
   mask-image: url('pictograms/chevron-down.svg');
@@ -604,7 +629,7 @@ summary:has(.button) {
   padding-inline-end: 0;
 }
 summary .button {
-  border: 1px solid var(--color-border-gray);
+  border: solid 1px var(--color-border-gray);
   border-radius: inherit;
   border-top-left-radius: 0;
   border-bottom-left-radius: 0;
@@ -615,15 +640,15 @@ summary span {
   width: 100%;
 }
 details[open] summary::before {
-  transform: scaleY(-1);
+  transform: rotate(180deg);
 }
 summary::marker {
   padding-left: 0.25em;
 }
-/* NOTE: use `details[open]::details-content` once widely available. */
+/* NOTE: use details[open]::details-content once widely available */
 details[open] ul {
-  background-color: white;
-  border: 1px solid var(--color-border-gray);
+  background: white;
+  border: solid 1px var(--color-border-gray);
   border-radius: 0.25em;
   box-shadow: 1px 1px 3px var(--color-border-gray);
   margin: -1px 0 0 0;
@@ -645,57 +670,3 @@ li input[type=checkbox] {
 li::marker {
   content: '';
 }
-/*
- * TODO:
- * * disable <label> containing disabled checkbox: `label:has(input[disabled])`,
- * * disabled label styling,
- * * focused label styling (currently only checkbox has focus),
- * * disabled checkbox blue square focus removal.
- * */
-
-#measurement_form {
-  min-width: 66%;
-  width: max-content;
-}
-.measurements-section {
-  overflow-x: auto;
-}
-body[data-measurements-view=wide] .measurements-compact,
-body[data-measurements-view=compact] .measurements-wide {
-  display: none;
-}
-body[data-measurements-view=compact] .view-toggle[data-view=compact],
-body[data-measurements-view=wide] .view-toggle[data-view=wide] {
-  background-color: var(--color-blue);
-  border-color: var(--color-blue);
-  color: white;
-  fill: white;
-}
-.chart-panel {
-  width: 100%;
-}
-#measurements tr.grouped td {
-  border-top: none;
-}
-#measurements tr.grouped .taken-at,
-#measurements tr.grouped .created-at {
-  visibility: hidden;
-}
-.measurements-wide td {
-  vertical-align: middle;
-  white-space: nowrap;
-}
-.wide-cell {
-  align-items: center;
-  display: inline-flex;
-  gap: 0.25em;
-}
-.wide-cell .button {
-  border: none;
-  font-size: inherit;
-  height: auto;
-  padding: 0;
-}
-.wide-cell button.link::after {
-  content: none;
-}

app/controllers/charts_controller.rb

@@ -1,12 +0,0 @@
-class ChartsController < ApplicationController
-  def index
-    readouts = current_user.readouts.includes(:quantity, :unit).order(:taken_at, :id)
-    @readouts_json = readouts.map { |r|
-      { takenAt: r.taken_at&.iso8601,
-        quantityId: r.quantity_id,
-        quantityName: r.quantity.name,
-        value: r.value.to_f,
-        unit: r.unit.symbol }
-    }.to_json
-  end
-end

app/controllers/measurements_controller.rb

@@ -1,12 +1,7 @@
 class MeasurementsController < ApplicationController
-  before_action :find_readout, only: [:destroy, :edit, :update]
-
-  before_action except: :index do
-    raise AccessForbidden unless current_user.at_least(:active)
-  end
-
   def index
-    @measurements = current_user.readouts.includes(:quantity, :unit).order(taken_at: :desc, id: :desc)
+    @measurements = []
+    #@measurements = current_user.units.ordered.includes(:base, :subunits)
   end
 
   def new
@@ -14,40 +9,8 @@ class MeasurementsController < ApplicationController
   end
 
   def create
-    taken_at = params.permit(:taken_at)[:taken_at]
-    readout_params = params.permit(readouts: Readout::ATTRIBUTES).fetch(:readouts, [])
-    @readouts = readout_params.map { |rp| current_user.readouts.build(rp.merge(taken_at: taken_at)) }
-
-    if @readouts.present? && @readouts.all?(&:valid?)
-      ActiveRecord::Base.transaction { @readouts.each(&:save!) }
-      flash.now[:notice] = t('.success', count: @readouts.size)
-    else
-      errors = @readouts.flat_map { |r| r.errors.full_messages }
-      flash.now[:alert] = errors.present? ? errors.first : t('.no_readouts')
-    end
-  end
-
-  def edit
-    @user_units = current_user.units.ordered
-  end
-
-  def update
-    if @readout.update(params.require(:readout).permit(:value, :unit_id, :taken_at))
-      flash.now[:notice] = t('.success')
-    else
-      @user_units = current_user.units.ordered
-      render :edit
-    end
   end
 
   def destroy
-    @readout.destroy!
-    flash.now[:notice] = t('.success')
-  end
-
-  private
-
-  def find_readout
-    @readout = current_user.readouts.find(params[:id])
   end
 end

app/controllers/quantities_controller.rb

@@ -8,10 +8,6 @@ class QuantitiesController < ApplicationController
     raise AccessForbidden unless current_user.at_least(:active)
   end
 
-  before_action only: [:new, :edit, :create, :update] do
-    @user_units = current_user.units.ordered
-  end
-
   def index
     @quantities = current_user.quantities.ordered.includes(:parent, :subquantities)
   end

app/controllers/user/profiles_controller.rb

@@ -1,6 +1,10 @@
 class User::ProfilesController < Devise::RegistrationsController
   def destroy
-    # TODO: Disallow/disable deletion for last admin account; update :edit view
+    if current_user.sole_admin?
+      redirect_back fallback_location: edit_user_registration_path,
+        alert: t(".sole_admin")
+      return
+    end
     super
   end
 

app/helpers/application_helper.rb

@@ -12,12 +12,6 @@ module ApplicationHelper
       labeled_field_for(method, options) { super }
     end
 
-    def submit(value = nil, options = {})
-      value, options = nil, value if value.is_a?(Hash)
-      options[:class] = @template.class_names('button', options[:class])
-      super
-    end
-
     private
 
     def labeled_field_for(method, options)
@@ -86,7 +80,6 @@ module ApplicationHelper
     def initialize(...)
       super(...)
       @default_options.merge!(@options.slice(:form))
-      @default_html_options.merge!(@options.slice(:form))
     end
 
     [:text_field, :password_field, :text_area].each do |selector|
@@ -103,28 +96,20 @@ module ApplicationHelper
 
     def number_field(method, options = {})
       attr_type = object.type_for_attribute(method)
-      case attr_type.type
-      when :decimal
+      if attr_type.type == :decimal
         options[:value] = object.public_send(method)&.to_scientific
         options[:step] ||= BigDecimal(10).power(-attr_type.scale)
         options[:max] ||= BigDecimal(10).power(attr_type.precision - attr_type.scale) -
           options[:step]
         options[:min] = options[:min] == :step ? options[:step] : options[:min]
         options[:min] ||= -options[:max]
-        options[:size] ||= attr_type.precision / 2
-      when :float
-        options[:size] ||= 6
       end
       super
     end
 
     def button(value = nil, options = {}, &block)
-      # #button does not use #objectify_options/@default_options
-      value, options = nil, value if value.is_a?(Hash)
-      options = options.merge(
-        @default_options.slice(:form),
-        class: @template.class_names('button', options[:class])
-      )
+      # button does not use #objectify_options
+      options.merge!(@options.slice(:form))
       super
     end
 
@@ -153,14 +138,12 @@ module ApplicationHelper
   end
 
   def tabular_form_with(**options, &block)
-    extra_options = {builder: TabularFormBuilder, class: 'tabular-form',
-                     html: {autocomplete: 'off'}}
+    extra_options = {builder: TabularFormBuilder, html: {autocomplete: 'off'}}
     form_with(**merge_attributes(options, extra_options), &block)
   end
 
   def svg_tag(source, label = nil, options = {})
-    label, options = nil, label if label.is_a? Hash
-    svg_tag = tag.svg(**options) do
+    svg_tag = tag.svg(options) do
       tag.use(href: "#{image_path(source + ".svg")}#icon")
     end
     label.blank? ? svg_tag : svg_tag + tag.span(label)
@@ -171,7 +154,6 @@ module ApplicationHelper
       ['measurements', 'scale-bathroom', :restricted],
       ['quantities', 'axis-arrow', :restricted, 'right'],
       ['units', 'weight-gram', :restricted],
-      ['charts', 'chart-line', :restricted],
       # TODO: display users tab only if >1 user present; sole_user?/sole_admin?
       ['users', 'account-multiple-outline', :admin],
     ]
@@ -230,8 +212,9 @@ module ApplicationHelper
       # Conversion of flash to Array only required because of Devise
       Array(messages).map do |message|
         tag.div class: "flash #{entry}" do
-          tag.span(sanitize(message)) +
-            svg_tag('pictograms/close-outline', {onclick: "this.parentElement.remove()"})
+          # TODO: change button text to svg to make it aligned vertically
+          tag.div(sanitize(message)) + tag.button(sanitize("×"), tabindex: -1,
+                                                  onclick: "this.parentElement.remove();")
         end
       end
     end.join.html_safe

app/helpers/quantities_helper.rb

@@ -1,9 +1,9 @@
 module QuantitiesHelper
-  def quantities_check_boxes(quantities)
+  def quantities_check_boxes
     # Closing <details> on focusout event depends on relatedTarget for internal
     # actions being non-null. To ensure this, all top-layer elements of
     # ::details-content must accept focus, e.g. <label> needs tabindex="-1" */
-    collection_check_boxes(nil, :quantity, quantities, :id, :to_s_with_depth,
+    collection_check_boxes(nil, :quantity, @quantities, :id, :to_s_with_depth,
                            include_hidden: false) do |b|
       content_tag :li, b.label(tabindex: -1) { b.check_box + b.text }
     end

app/javascript/application.js

@@ -9,196 +9,6 @@ function showPage(event) {
 }
 document.addEventListener('turbo:load', showPage)
 
-function groupMeasurements() {
-  var tbody = document.getElementById('measurements');
-  if (!tbody) return;
-  var prevTakenAt = null;
-  Array.from(tbody.querySelectorAll('tr[data-taken-at]'))
-    .filter(function(row) { return row.style.display !== 'none' })
-    .forEach(function(row) {
-      var takenAt = row.dataset.takenAt;
-      row.classList.toggle('grouped', takenAt !== null && takenAt === prevTakenAt);
-      prevTakenAt = takenAt;
-    });
-}
-
-function buildWideTable() {
-  var tbody = document.getElementById('measurements');
-  var wideContainer = document.getElementById('measurements-wide');
-  if (!tbody || !wideContainer) return;
-
-  var rows = Array.from(tbody.querySelectorAll('tr[data-taken-at]'));
-
-  if (rows.length === 0) { wideContainer.innerHTML = ''; return; }
-
-  // Unique quantities in alphabetical order
-  var qOrder = [], qSeen = new Set();
-  rows.forEach(function(r) {
-    var id = r.dataset.quantityId;
-    if (id && !qSeen.has(id)) { qSeen.add(id); qOrder.push({id: id, name: r.dataset.quantityName}); }
-  });
-  qOrder.sort(function(a, b) { return a.name.localeCompare(b.name); });
-
-  // Group rows by taken_at, preserving order
-  var groups = [], groupMap = new Map();
-  rows.forEach(function(r) {
-    var key = r.dataset.takenAt || '';
-    if (!groupMap.has(key)) { var g = {rows: []}; groups.push(g); groupMap.set(key, g); }
-    groupMap.get(key).rows.push(r);
-  });
-
-  // Read column headers from compact thead
-  var ths = document.querySelectorAll('.measurements-compact thead th');
-  var takenAtHeader = ths[3] ? ths[3].textContent : '';
-  var createdAtHeader = ths[4] ? ths[4].textContent : '';
-
-  var table = document.createElement('table');
-  table.className = 'items-table';
-
-  // Header
-  var thead = table.createTHead();
-  var hrow = thead.insertRow();
-  [takenAtHeader].concat(qOrder.map(function(q) { return q.name; })).concat([createdAtHeader]).forEach(function(text) {
-    var th = document.createElement('th');
-    th.textContent = text;
-    hrow.appendChild(th);
-  });
-
-  // Body
-  var tbodyEl = table.createTBody();
-  groups.forEach(function(group) {
-    var tr = tbodyEl.insertRow();
-
-    // Taken at
-    var tdTime = tr.insertCell();
-    var takenAtEl = group.rows[0].querySelector('.taken-at');
-    tdTime.textContent = takenAtEl ? takenAtEl.textContent : '';
-
-    // One cell per quantity
-    qOrder.forEach(function(q) {
-      var td = tr.insertCell();
-      var readoutRow = group.rows.find(function(r) { return r.dataset.quantityId === q.id; });
-      if (readoutRow) {
-        td.className = 'ralign';
-        var wrap = document.createElement('span');
-        wrap.className = 'wide-cell';
-        var editLink = readoutRow.querySelector('a.link');
-        if (editLink) {
-          var editUrl = editLink.href + (editLink.href.includes('?') ? '&' : '?') + 'view=wide';
-          var btn = document.createElement('button');
-          btn.className = 'link';
-          btn.type = 'button';
-          btn.dataset.editUrl = editUrl;
-          btn.addEventListener('click', function() { editMeasurementWide(this.dataset.editUrl); this.blur(); });
-          btn.textContent = readoutRow.dataset.value;
-          wrap.appendChild(btn);
-          wrap.appendChild(document.createTextNode('\u00a0' + readoutRow.dataset.unit));
-        } else {
-          wrap.appendChild(document.createTextNode(readoutRow.dataset.value + '\u00a0' + readoutRow.dataset.unit));
-        }
-        var srcActions = readoutRow.querySelector('td.flex');
-        if (srcActions) srcActions.querySelectorAll('form').forEach(function(f) {
-          var cloned = f.cloneNode(true);
-          var span = cloned.querySelector('button span');
-          if (span) span.remove();
-          wrap.appendChild(cloned);
-        });
-        td.appendChild(wrap);
-      }
-    });
-
-    // Created at (from first row of group)
-    var tdCreated = tr.insertCell();
-    var createdAtEl = group.rows[0].querySelector('.created-at');
-    tdCreated.textContent = createdAtEl ? createdAtEl.textContent : '';
-  });
-
-  wideContainer.innerHTML = '';
-  wideContainer.appendChild(table);
-}
-
-function buildCharts() {
-  var container = document.getElementById('measurements-charts');
-  var dataEl = document.getElementById('charts-data');
-  if (!container || !dataEl) return;
-
-  var readouts = JSON.parse(dataEl.textContent);
-  container.innerHTML = '';
-  if (readouts.length === 0) return;
-
-  // Data arrives sorted by taken_at from the server; group into per-quantity traces
-  var quantities = new Map();
-  readouts.forEach(function(r) {
-    if (!r.takenAt) return;
-    if (!quantities.has(r.quantityId)) {
-      quantities.set(r.quantityId, { name: r.quantityName, unit: r.unit, x: [], y: [] });
-    }
-    var q = quantities.get(r.quantityId);
-    q.x.push(r.takenAt);
-    q.y.push(r.value);
-  });
-
-  var traces = [];
-  quantities.forEach(function(q) {
-    traces.push({
-      x: q.x,
-      y: q.y,
-      mode: 'lines+markers',
-      type: 'scatter',
-      name: q.name + ' (' + q.unit + ')',
-      marker: { size: 5 }
-    });
-  });
-
-  var div = document.createElement('div');
-  div.className = 'chart-panel';
-  container.appendChild(div);
-
-  Plotly.newPlot(div, traces, {
-    xaxis: { type: 'date', tickformat: '%Y-%m-%d %H:%M' },
-    yaxis: {},
-    margin: { t: 20, r: 20, b: 80, l: 60 },
-    paper_bgcolor: 'transparent',
-    plot_bgcolor: 'transparent',
-    font: { family: 'system-ui' },
-    legend: { orientation: 'h', y: -0.25 }
-  }, { responsive: true, displayModeBar: false });
-}
-
-function getMeasurementsView() {
-  return localStorage.getItem('measurements-view') || 'compact';
-}
-
-function applyMeasurementsView(view) {
-  document.body.dataset.measurementsView = view;
-  if (view === 'wide') buildWideTable();
-}
-
-function setMeasurementsView(view) {
-  localStorage.setItem('measurements-view', view);
-  applyMeasurementsView(view);
-}
-window.setMeasurementsView = setMeasurementsView
-
-document.addEventListener('turbo:load', function() {
-  if (document.getElementById('charts-data')) {
-    buildCharts();
-    return;
-  }
-  var tbody = document.getElementById('measurements');
-  if (!tbody) return;
-  groupMeasurements();
-  applyMeasurementsView(getMeasurementsView());
-  new MutationObserver(function() {
-    groupMeasurements();
-    var view = getMeasurementsView();
-    if (view === 'wide') buildWideTable();
-  }).observe(tbody, {
-    childList: true, subtree: true,
-    attributes: true, attributeFilter: ['style']
-  });
-})
-
 function detailsChange(event) {
   var target = event.currentTarget
   var count = target.querySelectorAll('input:checked:not([disabled])').length
@@ -227,65 +37,6 @@ window.detailsObserver = new MutationObserver((mutations) => {
   mutations[0].target.dispatchEvent(new Event('change', {bubbles: true}))
 });
 
-function editMeasurementWide(url) {
-  fetch(url, {
-    headers: {
-      'Accept': 'text/vnd.turbo-stream.html',
-      'X-Requested-With': 'XMLHttpRequest'
-    }
-  })
-  .then(response => response.text())
-  .then(html => {
-    Turbo.renderStreamMessage(html);
-    requestAnimationFrame(() => {
-      var panel = document.getElementById('measurement_edit_form');
-      if (panel && panel.firstElementChild) {
-        panel.scrollIntoView({behavior: 'smooth', block: 'nearest'});
-      }
-    });
-  });
-}
-window.editMeasurementWide = editMeasurementWide
-
-function readoutUnitChanged(select) {
-  var button = select.closest('tr').querySelector('.set-default-unit');
-  if (select.value && select.value !== select.dataset.defaultUnitId) {
-    button.removeAttribute('disabled');
-    button.removeAttribute('aria-disabled');
-    button.removeAttribute('tabindex');
-  } else {
-    button.setAttribute('disabled', 'disabled');
-    button.setAttribute('aria-disabled', 'true');
-    button.setAttribute('tabindex', '-1');
-  }
-}
-window.readoutUnitChanged = readoutUnitChanged
-
-function setDefaultUnit(button) {
-  var select = button.closest('tr').querySelector('select[data-default-unit-id]');
-  var params = new URLSearchParams();
-  params.append('quantity[default_unit_id]', select.value);
-
-  fetch(button.dataset.path, {
-    body: params,
-    headers: {
-      'Accept': 'text/vnd.turbo-stream.html',
-      'X-CSRF-Token': document.head.querySelector('meta[name=csrf-token]').content,
-      'X-Requested-With': 'XMLHttpRequest'
-    },
-    method: 'PATCH'
-  })
-  .then(response => {
-    if (response.ok) {
-      select.dataset.defaultUnitId = select.value;
-      readoutUnitChanged(select);
-    }
-    return response.text();
-  })
-  .then(html => Turbo.renderStreamMessage(html));
-}
-window.setDefaultUnit = setDefaultUnit
-
 function formValidate(event) {
   var id = event.submitter.getAttribute("data-validate")
   if (!id) return;

app/models/quantity.rb

@@ -1,10 +1,9 @@
 class Quantity < ApplicationRecord
-  ATTRIBUTES = [:name, :description, :parent_id, :default_unit_id]
+  ATTRIBUTES = [:name, :description, :parent_id]
   attr_cached :depth, :pathname
 
   belongs_to :user, optional: true
   belongs_to :parent, optional: true, class_name: "Quantity"
-  belongs_to :default_unit, optional: true, class_name: "Unit"
   has_many :subquantities, ->{ order(:name) }, class_name: "Quantity",
     inverse_of: :parent, dependent: :restrict_with_error
 

app/models/readout.rb

@@ -1,5 +1,5 @@
 class Readout < ApplicationRecord
-  ATTRIBUTES = [:quantity_id, :value, :unit_id, :taken_at]
+  ATTRIBUTES = [:quantity_id, :value, :unit_id]
 
   belongs_to :user
   belongs_to :quantity

app/models/user.rb

@@ -29,4 +29,11 @@ class User < ApplicationRecord
   def at_least(status)
     User.statuses[self.status] >= User.statuses[status]
   end
+
+  # Returns true when this user is the only admin account in the system.
+  # Used to block actions that would leave the application without an admin
+  # (account deletion, status demotion).
+  def sole_admin?
+    admin? && !User.admin.where.not(id: id).exists?
+  end
 end

app/views/charts/index.html.erb

@@ -1,2 +0,0 @@
-<div class="main-area" id="measurements-charts"></div>
-<script id="charts-data" type="application/json"><%= raw @readouts_json %></script>

app/views/default/units/_unit.html.erb

@@ -5,7 +5,7 @@
   </td>
 
   <% if current_user.at_least(:active) %>
-    <td class="flex">
+    <td class="actions">
       <% unless unit.portable.nil? %>
         <% if unit.default? %>
           <%= image_button_to_if unit.portable?, t('.import'), 'download-outline',

app/views/default/units/index.html.erb

@@ -8,7 +8,7 @@
     class: 'tools-area' %>
 </div>
 
-<table class="main-area items-table">
+<table class="main-area items">
   <thead>
     <tr>
       <th><%= Unit.human_attribute_name(:symbol) %></th>

app/views/layouts/application.html.erb

@@ -14,7 +14,6 @@
     <%= csp_meta_tag %>
 
     <%= stylesheet_link_tag "spreadsheet" %>
-    <script src="https://cdn.plot.ly/plotly-basic-2.35.2.min.js"></script>
     <%= javascript_importmap_tags %>
 
     <%#= turbo_page_requires_reload_tag %>
@@ -24,10 +23,10 @@
   </head>
 
   <body>
-    <header class="flex">
+    <header class="hflex">
       <%= image_link_to t(".source_code"), "code-braces", source_code_url %>
       <%= image_link_to t(".issue_tracker"), "bug-outline", issue_tracker_url,
-        class: "rextend" %>
+            class: "extendedright" %>
       <% if user_signed_in? %>
         <%= image_link_to_unless_current(current_user, "account-wrench-outline",
           edit_user_registration_path) %>

app/views/measurements/_edit_form.html.erb

@@ -1,24 +0,0 @@
-<%= tabular_fields_for @readout, form: form_tag do |form| %>
-  <%- tag.tr id: row, class: "form", onkeydown: "formProcessKey(event)",
-    data: {form: form_tag, hidden_row: hidden_row, link: link} do %>
-    <td><%= @readout.quantity %></td>
-    <td class="ralign">
-      <%= form.number_field :value, required: true, autofocus: true %>
-    </td>
-    <td>
-      <%= form.collection_select :unit_id, @user_units, :id,
-        ->(u){ sanitize('&emsp;' * (u.base_id? ? 1 : 0) + u.symbol) },
-        {}, required: true %>
-    </td>
-    <td>
-      <%= form.datetime_field :taken_at %>
-    </td>
-    <td></td>
-    <td class="flex">
-      <%= form.button %>
-      <%= image_link_to t(:cancel), "close-outline", measurements_path,
-        class: 'dangerous', name: :cancel,
-        onclick: render_turbo_stream('edit_form_close', {row: row}) %>
-    </td>
-  <% end %>
-<% end %>

app/views/measurements/_edit_form_close.html.erb

@@ -1,2 +0,0 @@
-<%= turbo_stream.close_form row %>
-<%= turbo_stream.update :flashes %>

app/views/measurements/_edit_panel.html.erb

@@ -1,33 +0,0 @@
-<% form_tag = dom_id(@readout, :edit, :form) %>
-<% row = dom_id(@readout, :edit) %>
-<% hidden_row = dom_id(@readout) %>
-
-<%= tabular_form_with model: @readout, url: measurement_path(@readout),
-  id: form_tag do |form| %>
-  <table class="items-table">
-    <tbody>
-      <%= tag.tr id: row, class: "form", onkeydown: "formProcessKey(event)",
-        data: {form: form_tag, hidden_row: hidden_row} do %>
-        <td><%= @readout.quantity %></td>
-        <td class="ralign">
-          <%= form.number_field :value, required: true, autofocus: true %>
-        </td>
-        <td>
-          <%= form.collection_select :unit_id, @user_units, :id,
-            ->(u){ sanitize('&emsp;' * (u.base_id? ? 1 : 0) + u.symbol) },
-            {}, required: true %>
-        </td>
-        <td>
-          <%= form.datetime_field :taken_at %>
-        </td>
-        <td></td>
-        <td class="flex">
-          <%= form.button %>
-          <%= image_link_to t(:cancel), "close-outline", measurements_path,
-            class: 'dangerous', name: :cancel,
-            onclick: render_turbo_stream('edit_form_close', {row: row}) %>
-        </td>
-      <% end %>
-    </tbody>
-  </table>
-<% end %>

app/views/measurements/_form.html.erb

@@ -1,22 +1,12 @@
 <%= tabular_form_with model: Measurement.new, id: :measurement_form,
-  class: 'topside-area flex vertical center',
-  html: {onkeydown: 'formProcessKey(event)'} do |form| %>
-
-  <table class="items-table center">
-    <tbody id="readouts">
-      <%= tabular_fields_for @measurement do |form| %>
-        <tr class="italic">
-          <td class="hexpand hmin50"><%= t '.taken_at_html' %></td>
-          <td colspan="3" class="ralign">
-            <%= form.datetime_field :taken_at, required: true, value: Time.current.strftime('%Y-%m-%dT%H:%M') %>
-          </td>
-        </tr>
-      <% end %>
-    </tbody>
+  class: 'topside-area vflex', html: {onkeydown: 'formProcessKey(event)'} do |form| %>
+  <table class="items centered">
+    <tbody id="readouts"></tbody>
   </table>
 
-  <%# TODO: right-click selection; unnecessary with hierarchical tags? %>
-  <details id="quantity_select" class="center hexpand" open
+  <div class="hflex">
+    <%# TODO: right-click selection %>
+    <details id="quantity_select" class="hexpand" open
              onkeydown="detailsProcessKey(event)">
       <summary autofocus>
         <!-- TODO: Set content with CSS when span empty to avoid duplication -->
@@ -27,11 +17,12 @@
           formaction: new_readout_path, formmethod: :get, formnovalidate: true,
           data: {turbo_stream: true} %>
       </summary>
-    <ul><%= quantities_check_boxes(@quantities) %></ul>
+      <ul><%= quantities_check_boxes %></ul>
     </details>
-
-  <div class="flex reverse">
     <%= form.button id: :create_measurement_button, disabled: true -%>
+  </div>
+
+  <div class="hflex reverse">
     <%= image_link_to t(:cancel), "close-outline", measurements_path, name: :cancel,
       class: 'dangerous', onclick: render_turbo_stream('form_close') %>
   </div>

app/views/measurements/_readout.html.erb

@@ -1,22 +0,0 @@
-<%= tag.tr id: dom_id(readout), data: {taken_at: readout.taken_at&.iso8601,
-  quantity_id: readout.quantity_id, quantity_name: readout.quantity.name,
-  value: format("%.10g", readout.value), unit: readout.unit.symbol} do %>
-  <td>
-    <% if current_user.at_least(:active) %>
-      <%= link_to readout.quantity, edit_measurement_path(readout),
-        class: 'link', onclick: 'this.blur();', data: {turbo_stream: true} %>
-    <% else %>
-      <%= readout.quantity %>
-    <% end %>
-  </td>
-  <td class="ralign"><%= format("%.10g", readout.value) %></td>
-  <td><%= readout.unit %></td>
-  <td class="taken-at"><%= l(readout.taken_at) if readout.taken_at %></td>
-  <td class="created-at"><%= l(readout.created_at) %></td>
-  <% if current_user.at_least(:active) %>
-    <td class="flex">
-      <%= image_button_to t('.destroy'), 'delete-outline', measurement_path(readout),
-        method: :delete, data: {turbo_stream: true} %>
-    </td>
-  <% end %>
-<% end %>

app/views/measurements/edit.turbo_stream.erb

@@ -1,18 +0,0 @@
-<% ids = {row: dom_id(@readout, :edit),
-          hidden_row: dom_id(@readout),
-          link: nil,
-          form_tag: dom_id(@readout, :edit, :form)} %>
-
-<% if params[:view] == 'wide' %>
-  <%= turbo_stream.update :measurement_edit_form, partial: 'edit_panel' %>
-  <%= turbo_stream.hide ids[:hidden_row] %>
-<% else %>
-  <%= turbo_stream.append :measurement_edit_form do %>
-    <%- tabular_form_with model: @readout, url: measurement_path(@readout),
-      html: {id: ids[:form_tag]} do %>
-    <% end %>
-  <% end %>
-  <%= turbo_stream.hide ids[:hidden_row] %>
-  <%= turbo_stream.remove ids[:row] %>
-  <%= turbo_stream.after @readout, partial: 'edit_form', locals: ids -%>
-<% end %>

app/views/measurements/index.html.erb

@@ -5,36 +5,10 @@
       id: :new_measurement_link, onclick: 'this.blur();',
       data: {turbo_stream: true} %>
   <% end %>
-  <%= image_button_tag '', 'view-rows', name: nil, type: 'button',
-    class: 'view-toggle', title: t('.view_compact'),
-    data: {view: 'compact'}, onclick: "setMeasurementsView('compact')" %>
-  <%= image_button_tag '', 'view-columns', name: nil, type: 'button',
-    class: 'view-toggle', title: t('.view_wide'),
-    data: {view: 'wide'}, onclick: "setMeasurementsView('wide')" %>
-
 </div>
 
-<div class="main-area measurements-section">
-  <%= tag.div id: :measurement_edit_form %>
-  <table class="items-table measurements-compact">
-    <thead>
-      <tr>
-        <th><%= Quantity.model_name.human %></th>
-        <th><%= Readout.human_attribute_name(:value) %></th>
-        <th><%= Unit.model_name.human %></th>
-        <th><%= Readout.human_attribute_name(:taken_at) %></th>
-        <th><%= Readout.human_attribute_name(:created_at) %></th>
-        <% if current_user.at_least(:active) %>
-          <th></th>
-        <% end %>
-      </tr>
-    </thead>
+<table class="main-area">
   <tbody id="measurements">
-      <%= render(partial: 'readout', collection: @measurements, as: :readout) || render_no_items %>
+    <%= render(@measurements) || render_no_items %>
   </tbody>
 </table>
-
-  <div id="measurements-wide" class="measurements-wide"></div>
-
-</div>
-

app/views/measurements/update.turbo_stream.erb

@@ -1,2 +0,0 @@
-<%= turbo_stream.close_form dom_id(@readout, :edit) %>
-<%= turbo_stream.replace @readout, partial: 'measurements/readout', locals: {readout: @readout} %>

app/views/quantities/_form.html.erb

@@ -8,13 +8,8 @@
     <td>
       <%= form.text_area :description, cols: 30, rows: 1, escape: false %>
     </td>
-    <td>
-      <%= form.collection_select :default_unit_id, @user_units, :id,
-        ->(u){ sanitize('&emsp;' * (u.base_id? ? 1 : 0) + u.symbol) },
-        {include_blank: true}, onchange: "this.dataset.changed = ''" %>
-    </td>
 
-    <td class="flex">
+    <td class="actions">
       <%= form.button %>
       <%= image_link_to t(:cancel), "close-outline", quantities_path, class: 'dangerous',
         name: :cancel, onclick: render_turbo_stream('form_close', {row: row}) %>

app/views/quantities/_quantity.html.erb

@@ -5,15 +5,14 @@
            data: {drag_path: reparent_quantity_path(quantity), drop_id: dom_id(quantity),
                   drop_id_param: "quantity[parent_id]"} do %>
 
-  <td style="--depth:<%= quantity.depth %>">
-    <%= link_to quantity, edit_quantity_path(quantity), class: 'link',
-      onclick: 'this.blur();', data: {turbo_stream: true} %>
+  <td class="link" style="--depth:<%= quantity.depth %>">
+    <%= link_to quantity, edit_quantity_path(quantity), onclick: 'this.blur();',
+      data: {turbo_stream: true} %>
   </td>
   <td><%= quantity.description %></td>
-  <td><%= quantity.default_unit&.symbol %></td>
 
   <% if current_user.at_least(:active) %>
-    <td class="flex">
+    <td class="actions">
       <%= image_link_to t('.new_subquantity'), 'plus-outline', new_quantity_path(quantity),
         id: dom_id(quantity, :new, :link), onclick: 'this.blur();', data: {turbo_stream: true} %>
 

app/views/quantities/index.html.erb

@@ -8,15 +8,13 @@
     class: 'tools-area' %>
 </div>
 
-<%# TODO: remove? form can be inserted directly, e.g. at the end of index %>
 <%= tag.div class: 'main-area', id: :quantity_form %>
 
-<table class="main-area items-table">
+<table class="main-area items">
   <thead>
     <tr>
       <th><%= Quantity.human_attribute_name(:name) %></th>
-      <th class="hexpand"><%= Quantity.human_attribute_name(:description) %></th>
-      <th><%= Quantity.human_attribute_name(:default_unit) %></th>
+      <th><%= Quantity.human_attribute_name(:description) %></th>
       <% if current_user.at_least(:active) %>
         <th><%= t :actions %></th>
         <th></th>
@@ -26,7 +24,7 @@
                ondragover: "dragOver(event)", ondrop: "drop(event)",
                ondragenter: "dragEnter(event)", ondragleave: "dragLeave(event)",
                data: {drop_id: "quantity_", drop_id_param: "quantity[parent_id]"} do %>
-      <th colspan="5"><%= t '.top_level_drop' %></th>
+      <th colspan="4"><%= t '.top_level_drop' %></th>
     <% end %>
   </thead>
   <tbody id="quantities">

app/views/readouts/_form.html.erb

@@ -1,31 +1,25 @@
 <%# TODO: add readout reordering by dragging %>
 <%= tabular_fields_for 'readouts[]', readout do |form| %>
   <%- tag.tr id: dom_id(readout.quantity, :new, :readout) do %>
-    <td>
-      <%# TODO: add grayed readout index (in separate column?) %>
-      <%= readout.quantity.relative_pathname(@superquantity) %>
-      <%= form.hidden_field :quantity_id %>
-    </td>
-    <td>
-      <%= form.number_field :value, required: true, autofocus: readout_counter == 0 %>
-    </td>
-    <td>
-      <%= form.collection_select :unit_id, @user_units, :id,
-        ->(u){ sanitize('&emsp;' * (u.base_id ? 1 : 0) + u.symbol) },
-        {prompt: '', disabled: '', selected: readout.quantity.default_unit_id || ''}, required: true,
-        data: {default_unit_id: readout.quantity.default_unit_id || ''},
-        onchange: "readoutUnitChanged(this)" %>
-    </td>
-    <td class="flex">
+    <td class="actions">
       <%# TODO: change to _link_ after giving up displaying relative paths %>
-      <%= image_button_tag '', 'check-circle-outline',
-        class: 'set-default-unit', name: nil, type: 'button', disabled: true,
-        title: t('readouts.form.set_default_unit'),
-        data: {path: quantity_path(readout.quantity)},
-        onclick: 'setDefaultUnit(this)' %>
       <%= image_button_tag '', 'delete-outline', class: 'dangerous', name: nil,
         formaction: discard_readouts_path(readout.quantity),
         formmethod: :get, formnovalidate: true, data: {turbo_stream: true} %>
     </td>
+    <td>
+      <%= readout.quantity.relative_pathname(@superquantity) %>
+    </td>
+    <td>
+      <%= form.number_field :value, required: true,
+        size: readout.type_for_attribute(:value).precision / 2,
+        autofocus: readout_counter == 0 %>
+    </td>
+    <td>
+      <%= form.hidden_field :quantity_id %>
+      <%= form.collection_select :unit_id, @user_units, :id,
+        ->(u){ sanitize('&emsp;' * (u.base_id ? 1 : 0) + u.symbol) },
+        {prompt: t('.select_unit'), disabled: '', selected: ''}, required: true %>
+    </td>
   <% end %>
 <% end %>

app/views/units/_form.html.erb

@@ -8,11 +8,11 @@
     <td>
       <%= form.text_area :description, cols: 30, rows: 1, escape: false %>
     </td>
-    <td>
+    <td class="number">
       <%= form.number_field :multiplier, required: true, size: 10, min: :step if @unit.base_id? %>
     </td>
 
-    <td class="flex">
+    <td class="actions">
       <%= form.button %>
       <%= image_link_to t(:cancel), "close-outline", units_path, class: 'dangerous',
         name: :cancel, onclick: render_turbo_stream('form_close', {row: row}) %>

app/views/units/_unit.html.erb

@@ -6,15 +6,14 @@
                   drop_id: dom_id(unit.base || unit),
                   drop_id_param: "unit[base_id]"} do %>
 
-  <td style="--depth:<%= unit.base_id? ? 1 : 0 %>">
-    <%= link_to unit, edit_unit_path(unit), class: 'link', onclick: 'this.blur();',
-      data: {turbo_stream: true} %>
+  <td class="link" style="--depth:<%= unit.base_id? ? 1 : 0 %>">
+    <%= link_to unit, edit_unit_path(unit), onclick: 'this.blur();', data: {turbo_stream: true} %>
   </td>
   <td><%= unit.description %></td>
-  <td class="ralign"><%= unit.multiplier.to_html %></td>
+  <td class="number"><%= unit.multiplier.to_html %></td>
 
   <% if current_user.at_least(:active) %>
-    <td class="flex">
+    <td class="actions">
       <% unless unit.base_id? %>
         <%= image_link_to t('.new_subunit'), 'plus-outline', new_unit_path(unit),
           id: dom_id(unit, :new, :link), onclick: 'this.blur();', data: {turbo_stream: true} %>

app/views/units/index.html.erb

@@ -7,14 +7,13 @@
     class: 'tools-area' %>
 </div>
 
-<%# TODO: remove? form can be inserted directly, e.g. at the end of index %>
 <%= tag.div id: :unit_form %>
 
-<table class="main-area items-table">
+<table class="main-area items">
   <thead>
     <tr>
       <th><%= Unit.human_attribute_name(:symbol) %></th>
-      <th class="hexpand"><%= Unit.human_attribute_name(:description) %></th>
+      <th><%= Unit.human_attribute_name(:description) %></th>
       <th><%= Unit.human_attribute_name(:multiplier) %></th>
       <% if current_user.at_least(:active) %>
         <th><%= t :actions %></th>

app/views/users/index.html.erb

@@ -1,4 +1,4 @@
-<table class="main-area items-table" id="users">
+<table class="main-area items" id="users">
   <thead>
     <tr>
       <th><%= User.human_attribute_name(:email) %></th>
@@ -11,7 +11,7 @@
   <tbody>
     <% @users.each do |user| %>
       <tr>
-        <td><%= link_to user, user_path(user), class: 'link' %></td>
+        <td class="link"><%= link_to user, user_path(user) %></td>
         <td>
           <% if user == current_user %>
             <%= user.status %>
@@ -22,11 +22,11 @@
             <% end %>
           <% end %>
         </td>
-        <td>
+        <td class="svg">
           <%= svg_tag 'pictograms/checkbox-marked-outline' if user.confirmed_at.present? %>
         </td>
         <td><%= l user.created_at, format: :without_tz %></td>
-        <td class="flex">
+        <td class="actions">
           <% if allow_disguise?(user) %>
             <%= image_link_to t('.disguise'), 'incognito', disguise_user_path(user) %>
           <% end %>

app/views/users/profiles/edit.html.erb

@@ -4,9 +4,8 @@
 <% end %>
 
 <div class="rightside-area buttongrid">
-  <%#= TODO: Disallow/disable deletion for last admin account, image_button_to_if %>
-  <%= image_button_to t('.delete'), 'account-remove-outline', user_registration_path,
-    form_class: 'tools-area', method: :delete, data: {turbo: false},
+  <%= image_button_to_if !current_user.sole_admin?, t('.delete'), 'account-remove-outline',
+    user_registration_path, form_class: 'tools-area', method: :delete, data: {turbo: false},
     onclick: {confirm: t('.confirm_delete')} %>
 </div>
 

app/views/users/profiles/new.html.erb

@@ -10,6 +10,7 @@
 
   <%= f.submit t(:register), data: {turbo: false} %>
 
+  <%# TODO: fix button text color after change link -> button %>
   <%= image_button_tag t(:resend_confirmation), 'email-sync-outline',
     class: 'auxiliary', formaction: user_confirmation_path, formnovalidate: true,
     data: {validate: f.field_id(:email)} %>

app/views/users/unlocks/new.html.erb

@@ -8,7 +8,7 @@
     <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
   </div>
 
-  <div class="flex">
+  <div class="actions">
     <%= f.submit "Resend unlock instructions" %>
   </div>
 <% end %>

config/environments/test.rb

@@ -58,7 +58,4 @@ Rails.application.configure do
   # config.action_view.annotate_rendered_view_with_filenames = true
 
   config.log_level = :info
-
-  # Allow Capybara's dynamic test server host (127.0.0.1:<random_port>)
-  config.hosts << '127.0.0.1'
 end

config/locales/en.yml

@@ -11,13 +11,8 @@ en:
   activerecord:
     attributes:
       quantity:
-        default_unit: Default unit
         description: Description
         name: Name
-      readout:
-        created_at: Recorded at
-        taken_at: Taken at
-        value: Value
       unit:
         base: Base unit
         description: Description
@@ -86,34 +81,16 @@ en:
       revert: Revert
       sign_out: Sign out
       source_code: Get code
-  readouts:
-    form:
-      set_default_unit: Set as default unit
-  charts:
-    navigation: Charts
   measurements:
     navigation: Measurements
     no_items: There are no measurements taken. You can Add some now.
     form:
-      select_quantity: select quantities...
-      taken_at_html: Measurement taken at 
+      select_quantity: select the measured quantities...
     index:
       new_measurement: Add measurement
-      view_compact: Compact view
-      view_wide: Wide view
-      view_charts: Charts
-    readout:
-      edit: Edit
-      destroy: Delete
-    create:
-      success:
-        one: Recorded 1 measurement.
-        other: Recorded %{count} measurements.
-      no_readouts: No readouts selected.
-    update:
-      success: Measurement updated.
-    destroy:
-      success: Measurement deleted.
+  readouts:
+    form:
+      select_unit: ...
   quantities:
     navigation: Quantities
     no_items: There are no configured quantities. You can Add some or Import from defaults.
@@ -185,6 +162,9 @@ en:
           New password:
           <br><em>leave blank to keep unchanged</em>
           %{password_length_hint_html}
+  registrations:
+    destroy:
+      sole_admin: You cannot delete the only admin account.
   actions: Actions
   add: Add
   apply: Apply

config/routes.rb

@@ -1,6 +1,5 @@
 Rails.application.routes.draw do
   resources :measurements
-  resources :charts, only: [:index]
 
   resources :readouts, only: [:new] do
     collection {get 'new/:id/discard', action: :discard, as: :discard}

db/migrate/20250121230456_create_readouts.rb

@@ -1,14 +1,10 @@
 class CreateReadouts < ActiveRecord::Migration[7.2]
   def change
     create_table :readouts do |t|
-      # Reference :user through :quantity (:measurement may be NULL).
-      t.references :measurement, foreign_key: true
+      t.references :user, null: false, foreign_key: true
       t.references :quantity, null: false, foreign_key: true
-      # :category + :value + :unit as a separate table? (NumericValue, TextValue)
-      t.integer :category, null: false, default: 0
-      t.float :value, null: false, limit: Float::MANT_DIG
       t.references :unit, foreign_key: true
-      # Move to Measurement?
+      t.decimal :value, null: false, precision: 30, scale: 15
       #t.references :collector, foreign_key: true
       #t.references :device, foreign_key: true
 

db/migrate/20260402000000_add_taken_at_to_readouts.rb

@@ -1,5 +0,0 @@
-class AddTakenAtToReadouts < ActiveRecord::Migration[7.2]
-  def change
-    add_column :readouts, :taken_at, :datetime
-  end
-end

db/migrate/20260403000000_add_default_unit_to_quantities.rb

@@ -1,5 +0,0 @@
-class AddDefaultUnitToQuantities < ActiveRecord::Migration[7.2]
-  def change
-    add_reference :quantities, :default_unit, foreign_key: {to_table: :units}, null: true
-  end
-end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) do
+ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) do
   create_table "quantities", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
     t.bigint "user_id"
     t.string "name", limit: 31, null: false
@@ -20,8 +20,6 @@ ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) do
     t.datetime "updated_at", null: false
     t.integer "depth", default: 0, null: false
     t.string "pathname", limit: 511, null: false
-    t.bigint "default_unit_id"
-    t.index ["default_unit_id"], name: "index_quantities_on_default_unit_id"
     t.index ["parent_id"], name: "index_quantities_on_parent_id"
     t.index ["user_id", "parent_id", "name"], name: "index_quantities_on_user_id_and_parent_id_and_name", unique: true
     t.index ["user_id"], name: "index_quantities_on_user_id"
@@ -34,7 +32,6 @@ ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) do
     t.decimal "value", precision: 30, scale: 15, null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.datetime "taken_at"
     t.index ["quantity_id", "created_at"], name: "index_readouts_on_quantity_id_and_created_at", unique: true
     t.index ["quantity_id"], name: "index_readouts_on_quantity_id"
     t.index ["unit_id"], name: "index_readouts_on_unit_id"
@@ -73,7 +70,6 @@ ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) do
   end
 
   add_foreign_key "quantities", "quantities", column: "parent_id", on_delete: :cascade
-  add_foreign_key "quantities", "units", column: "default_unit_id"
   add_foreign_key "quantities", "users"
   add_foreign_key "readouts", "quantities"
   add_foreign_key "readouts", "units"

test/controllers/charts_controller_test.rb

@@ -1,63 +0,0 @@
-require "test_helper"
-
-class ChartsControllerTest < ActionDispatch::IntegrationTest
-  setup do
-    host! '127.0.0.1'
-    @user = users(:alice)
-    post new_user_session_path, params: { user: { email: @user.email, password: 'alice' } }
-    @quantity = @user.quantities.create!(name: 'Weight')
-    @unit = @user.units.create!(symbol: 'kg')
-  end
-
-  test "requires authentication" do
-    delete destroy_user_session_path
-    get charts_path
-    assert_response :redirect
-  end
-
-  test "index returns ok" do
-    get charts_path
-    assert_response :success
-  end
-
-  test "embeds readout data as JSON in script tag" do
-    users(:alice).readouts.create!(quantity: @quantity, unit: @unit, value: 82.5, taken_at: 1.day.ago)
-
-    get charts_path
-
-    assert_select 'script#charts-data[type="application/json"]' do |elements|
-      data = JSON.parse(elements.first.children.first.to_s)
-      assert_equal 1, data.size
-      assert_equal 'Weight', data.first['quantityName']
-      assert_in_delta 82.5, data.first['value']
-      assert_equal 'kg', data.first['unit']
-      assert_not_nil data.first['takenAt']
-    end
-  end
-
-  test "orders readouts by taken_at ascending" do
-    older = users(:alice).readouts.create!(quantity: @quantity, unit: @unit, value: 80.0, taken_at: 2.days.ago)
-    newer = users(:alice).readouts.create!(quantity: @quantity, unit: @unit, value: 82.5, taken_at: 1.day.ago)
-
-    get charts_path
-
-    assert_select 'script#charts-data[type="application/json"]' do |elements|
-      data = JSON.parse(elements.first.children.first.to_s)
-      assert_equal older.taken_at.iso8601, data.first['takenAt']
-      assert_equal newer.taken_at.iso8601, data.last['takenAt']
-    end
-  end
-
-  test "does not expose other users readouts" do
-    bob_quantity = users(:bob).quantities.create!(name: 'Steps')
-    bob_unit = users(:bob).units.create!(symbol: 'steps')
-    users(:bob).readouts.create!(quantity: bob_quantity, unit: bob_unit, value: 5000, taken_at: 1.day.ago)
-
-    get charts_path
-
-    assert_select 'script#charts-data[type="application/json"]' do |elements|
-      data = JSON.parse(elements.first.children.first.to_s)
-      assert data.none? { |r| r['quantityName'] == 'Steps' }, "Bob's data must not appear"
-    end
-  end
-end

test/controllers/measurements_controller_test.rb

@@ -1,7 +1,8 @@
 require "test_helper"
 
 class MeasurementsControllerTest < ActionDispatch::IntegrationTest
-  # test "the truth" do
-  #   assert true
+  #test "should get index" do
+  #  get measurements_index_url
+  #  assert_response :success
   #end
 end

test/controllers/registrations_controller_test.rb

@@ -0,0 +1,18 @@
+require "test_helper"
+
+class RegistrationsControllerTest < ActionDispatch::IntegrationTest
+  test "sole admin cannot delete account" do
+    sign_in users(:admin)
+    delete user_registration_path
+    assert_redirected_to edit_user_registration_path
+    assert_equal t("registrations.destroy.sole_admin"), flash[:alert]
+    assert User.exists?(users(:admin).id)
+  end
+
+  test "non-admin can delete account" do
+    sign_in users(:alice)
+    assert_difference ->{ User.count }, -1 do
+      delete user_registration_path
+    end
+  end
+end

test/system/charts_test.rb

@@ -1,26 +0,0 @@
-require "application_system_test_case"
-
-class ChartsTest < ApplicationSystemTestCase
-  setup do
-    @user = sign_in(user: users(:alice))
-    @quantity = @user.quantities.create!(name: 'Weight')
-    @unit = @user.units.create!(symbol: 'kg')
-    @user.readouts.create!(quantity: @quantity, unit: @unit, value: 82.5, taken_at: 1.day.ago)
-    @user.readouts.create!(quantity: @quantity, unit: @unit, value: 83.1, taken_at: Time.now)
-    visit charts_path
-  end
-
-  test "charts page is reachable from navigation" do
-    visit root_path
-    click_on t('charts.navigation')
-    assert_current_path charts_path
-  end
-
-  test "renders Plotly chart panel" do
-    assert_selector '#measurements-charts .chart-panel', wait: 5
-  end
-
-  test "chart legend shows quantity name with unit" do
-    assert_text 'Weight (kg)', wait: 5
-  end
-end

test/system/measurements_test.rb

@@ -1,64 +0,0 @@
-require "application_system_test_case"
-
-class MeasurementsTest < ApplicationSystemTestCase
-  setup do
-    @user = sign_in(user: users(:alice))
-
-    @quantity = @user.quantities.create!(name: 'Weight')
-    @unit = @user.units.create!(symbol: 'kg')
-    @readout = @user.readouts.create!(quantity: @quantity, unit: @unit, value: 82.5)
-
-    visit measurements_path
-  end
-
-  test "index shows quantity name as edit link for active user" do
-    within 'tbody' do
-      assert_selector :link, exact_text: @quantity.name
-    end
-  end
-
-  test "edit opens inline form on quantity link click" do
-    within 'tbody' do
-      click_on @quantity.name
-      assert_selector ':focus'
-      assert_selector 'input[name="readout[value]"]'
-    end
-  end
-
-  test "edit and update measurement value" do
-    within 'tbody' do
-      click_on @quantity.name
-      fill_in 'readout[value]', with: '83.1'
-      assert_difference ->{ @readout.reload.value }, 83.1 - @readout.value do
-        click_on t('helpers.submit.update')
-      end
-      assert_no_selector :fillable_field
-      assert_selector :link, exact_text: @quantity.name
-    end
-    assert_selector '.flash.notice', text: t('measurements.update.success')
-  end
-
-  test "cancel edit restores original row" do
-    within 'tbody' do
-      click_on @quantity.name
-      assert_selector 'input[name="readout[value]"]'
-      click_on t(:cancel)
-      assert_no_selector :fillable_field
-      assert_selector :link, exact_text: @quantity.name
-    end
-  end
-
-  test "wide view edit opens panel form" do
-    @readout.update!(taken_at: Time.now)
-    visit measurements_path
-    execute_script("localStorage.removeItem('measurements-view')")
-    visit measurements_path
-
-    find('button[data-view="wide"]').click
-    within '#measurements-wide' do
-      assert_text format("%.10g", 82.5), wait: 3
-      find('button.link').click
-    end
-    assert_selector '#measurement_edit_form input[name="readout[value]"]', wait: 5
-  end
-end

test/system/quantities_test.rb

@@ -1,45 +0,0 @@
-require "application_system_test_case"
-
-class QuantitiesTest < ApplicationSystemTestCase
-  setup do
-    @user = sign_in(user: users(:alice))
-    @unit = @user.units.create!(symbol: 'kg')
-    @quantity = @user.quantities.create!(name: 'Weight')
-    visit quantities_path
-  end
-
-  test "update button turns red when default unit changes" do
-    click_on 'Weight'
-
-    button = find('button[name=button]')
-    initial_color = evaluate_script("getComputedStyle(arguments[0]).backgroundColor", button)
-
-    select 'kg', from: 'quantity[default_unit_id]'
-
-    changed_color = evaluate_script("getComputedStyle(arguments[0]).backgroundColor", button)
-    refute_equal initial_color, changed_color, "Button color should change when default unit is altered"
-  end
-
-  test "saving default unit pre-selects it in measurements form" do
-    click_on 'Weight'
-    select 'kg', from: 'quantity[default_unit_id]'
-    click_on t('helpers.submit.update')
-    assert_selector '.flash.notice'
-
-    @quantity.reload
-    assert_equal @unit.id, @quantity.default_unit_id
-
-    visit measurements_path
-    find(:link_or_button, t('measurements.index.new_measurement')).click
-    assert_selector '#measurement_form'
-
-    within '#quantity_select' do
-      check 'Weight'
-    end
-    find('button[formaction]').click
-
-    within 'tbody#readouts' do
-      assert_selector "option[value='#{@unit.id}'][selected]"
-    end
-  end
-end

test/system/users_test.rb

@@ -182,8 +182,8 @@ class UsersTest < ApplicationSystemTestCase
     assert_title 'Access is forbidden to this page (403)'
   end
 
-  test 'delete profile' do
-    user = sign_in
+  test "delete profile" do
+    user = sign_in user: users.reject(&:admin?).select(&:confirmed?).sample
     # TODO: remove condition after root_url changed to different path than
     # profile in routes.rb
     unless has_current_path?(edit_user_registration_path)
@@ -196,7 +196,15 @@ class UsersTest < ApplicationSystemTestCase
     assert_text t("devise.registrations.destroyed")
   end
 
-  test 'index forbidden for non admin' do
+  test "sole admin cannot delete profile" do
+    sign_in user: users(:admin)
+    unless has_current_path?(edit_user_registration_path)
+      first(:link_or_button, users(:admin).email).click
+    end
+    assert find(:button, t("users.registrations.edit.delete"))[:disabled]
+  end
+
+  test "index forbidden for non admin" do
     sign_in user: users.reject(&:admin?).select(&:confirmed?).sample
     visit users_path
     assert_title "Access is forbidden to this page (403)"
@@ -229,7 +237,7 @@ class UsersTest < ApplicationSystemTestCase
       user = User.find_by_email!(first(:link).text)
       inject_button_to first('td:not(.link)'), "update status", user_path(user), method: :patch,
         params: {user: {status: User.statuses.keys.sample}}, data: {turbo: false}
-      execute_script("arguments[0].click()", find_button("update status"))
+      click_on "update status"
     end
     assert_title 'The change you wanted was rejected (422)'
   end