Add index on readouts(user_id, taken_at)

MeasurementsController#index orders by taken_at desc; without an index
this scan grows linearly with the readout count. The composite index
on (user_id, taken_at) covers both the implicit user_id filter from
the association scope and the ORDER BY clause.

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

CLAUDE.md

@@ -0,0 +1,84 @@
+# 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

app/assets/stylesheets/application.css

@@ -18,14 +18,12 @@
 /* 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>; <a> as link/button),
+ * 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.
  *
  * NOTE: style in a modular way, similar to how CSS @scope would be used,
  * to make transition easier once @scope is widely available. */
-/* TODO: review styles with multiple selectors and try to convert them to the same
- * specificity. */
 :root {
   --color-focus-gray: #f3f3f3;
   --color-border-gray: #dddddd;
@@ -57,8 +55,8 @@
 :focus-visible {
   outline: none;
 }
-/* NOTE: move to higher priority layer instead of using !important? */
+/* NOTE: move to higher priority layer instead of using !important?; add CSS
-/* TODO: add CSS @layer requirements in README */
+ * @layer requirements in README */
 [disabled] {
   border-color: var(--color-border-gray) !important;
   color: var(--color-border-gray) !important;
@@ -80,10 +78,13 @@
  *  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;
@@ -101,7 +102,14 @@ textarea {
   border-radius: 0.25em;
   padding: 0.2em 0.4em;
 }
-svg,
+svg {
+  height: 1.4em;
+  margin: 0 0.2em 0 0;
+  width: 1.4em;
+}
+svg:last-child {
+  margin-right: 0;
+}
 textarea {
   margin: 0;
 }
@@ -153,6 +161,10 @@ table form summary,
 table form textarea {
   color: inherit;
 }
+table svg:not(:only-child) {
+  height: 1.25em;
+  width: 1.25em;
+}
 input:focus-visible,
 select:focus-visible,
 select:focus-within,
@@ -214,21 +226,17 @@ textarea:invalid {
   padding: 0.6em 0.5em;
   width: fit-content;
 }
+.link {
+  color: inherit;
+  text-decoration: underline 1px var(--color-border-gray);
+  text-underline-offset: 0.25em;
+}
 [name=cancel],
 .auxiliary {
   border-color: var(--color-border-gray);
   color: var(--color-nav-gray);
   fill: var(--color-nav-gray);
 }
-.button > svg,
-.tab > svg {
-  height: 1.4em;
-  width: 1.4em;
-}
-.button > svg:not(:last-child),
-.tab > svg:not(:last-child) {
-  margin-right: 0.2em;
-}
 .button:focus-visible,
 .tab:focus-visible,
 .tab:hover {
@@ -244,6 +252,13 @@ textarea:invalid {
   background-color: var(--color-red);
   border-color: var(--color-red);
 }
+.link:focus-visible {
+  text-decoration-color: var(--color-gray);
+}
+.link:hover {
+  color: var(--color-blue);
+  text-decoration-color: var(--color-blue);
+}
 table .button {
   border-color: var(--color-border-gray);
   color: var(--color-table-gray);
@@ -251,15 +266,6 @@ table .button {
   height: 100%;
   padding: 0.4em;
 }
-/* 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. */
-/* TODO: apply link class to non-button/-tab links. Add light underscore for links? */
-input[type=text]:read-only,
-textarea:read-only {
-  border: none;
-  padding-inline: 0;
-}
 
 
 /* NOTE: collapse gaps around empty rows (`topside`) once possible with
@@ -271,16 +277,16 @@ 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:not(:has(.topside-area)) {
+body:has(> .topside-area) {
   grid-template-areas:
     "header    header  header"
     "nav       nav     nav"
+    "leftside  topside rightside"
     "leftside  main    rightside";
 }
 
@@ -431,14 +437,18 @@ header {
 
 .tabular-form table {
   border: none;
+  border-spacing: 0.4em 0;
+  margin-inline: -0.4em;
 }
 .tabular-form table td {
   border: none;
-  text-align: left;
   vertical-align: middle;
 }
-.tabular-form table td:first-child {
+.tabular-form table td {
-  color: inherit;
+  padding-inline: 0;
+}
+.tabular-form table :is(form, input, select, textarea):only-child {
+  margin-inline-start: 0;
 }
 
 
@@ -457,59 +467,41 @@ header {
   background-color: var(--color-focus-gray);
 }
 .items-table th {
-  padding-block: 0.75em;
+  padding: 0.75em 0 0.75em 1em;
   text-align: center;
 }
-.items-table th,
-.items-table td {
-  padding-inline: 1em 0;
-}
-/* For <a> to fill <td> completely, we use an `::after` pseudoelement. */
-.items-table td.link {
-  padding: 0;
-  position: relative;
-}
-.items-table td.link a {
-  color: inherit;
-  font: inherit;
-}
-.items-table td.link a::after {
-  content: '';
-  inset: 0;
-  position: absolute;
-}
-.items-table td:first-child {
-  padding-inline-start: calc(1em + var(--depth) * 0.8em);
-}
-.items-table td:has(input, select, textarea) {
-  padding-inline-start: calc(0.6em - 0.9px);
-}
-.items-table td:first-child:has(input, select, textarea) {
-  padding-inline-start: calc(0.6em + var(--depth) * 0.8em - 0.9px);
-}
 .items-table th:last-child {
   padding-inline-end: 0.4em;
 }
-.items-table td:last-child {
-  padding-inline-end: 0.1em;
-}
 .items-table td {
   border-top: 1px solid var(--color-border-gray);
   height: 2.4em;
-  padding-block: 0.1em;
+  padding: 0.1em 0 0.1em calc(1em + var(--depth) * 0.8em);
 }
-.items-table .actions {
+.items-table td:last-child {
-  display: flex;
+  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) {
+  position: relative;
+}
+.items-table .link::after {
+  content: '';
+  inset: -1px 0 0 0;
+  position: absolute;
+}
+.items-table .flex {
   gap: 0.4em;
   justify-content: end;
 }
-.items-table .actions.centered {
+.items-table .dropzone {
-  justify-content: center;
-}
-.items-table tr.dropzone {
   position: relative;
 }
-.items-table tr.dropzone::after {
+.items-table .dropzone::after {
   content: '';
   inset: 1px 0 0 0;
   position: absolute;
@@ -517,72 +509,37 @@ header {
   outline-offset: -1px;
   z-index: var(--z-index-table-row-outline);
 }
-.items-table td.handle {
+.items-table .handle {
-  cursor: move;
+  cursor: grab;
 }
-.items-table tr.form td {
+.items-table .form td {
   vertical-align: top;
 }
-
-/* TODO: replace `:hover:focus-visible` combos with proper LOVE style order. */
-/* TODO: update table styling: simplify selectors, deduplicate, remove non-font rem. */
-.items-table td.link a:hover,
-.items-table td.link a:focus-visible,
-.items-table td.link a:hover:focus-visible {
-  text-decoration: underline;
-  text-decoration-thickness: 0.05rem;
-  text-underline-offset: 0.2rem;
-}
-.items-table td.link a:hover {
-  color: var(--color-blue);
-}
-.items-table td.link a:focus-visible {
-  text-decoration-color: var(--color-gray);
-}
-.items-table td.link a:hover:focus-visible {
-  color: var(--color-dark-blue);
-}
-
 .items-table td:not(:first-child),
 .grayed {
   color: var(--color-table-gray);
-  fill: var(--color-table-gray);
+  fill: var(--color-gray);
 }
-.items-table svg {
+.items-table td:has(> svg:only-child) {
-  height: 1rem;
-  vertical-align: middle;
-  width: 1rem;
-}
-.items-table svg:last-child {
-  height: 1.2rem;
-  width: 1.2rem;
-}
-.items-table td.svg {
   text-align: center;
 }
-.items-table td.number {
-  text-align: right;
-}
 
 
-.centered {
+.center {
   margin: 0 auto;
 }
-.extendedright {
-  margin-right: auto;
-}
 .hexpand {
   width: 100%;
 }
-.hflex {
+.flex {
   display: flex;
   gap: 0.8em;
 }
-.hflex.reverse {
+.flex.reverse {
   flex-direction: row-reverse;
 }
-.hflex.centered {
+.flex.vertical {
-  justify-content: center;
+  flex-direction: column;
 }
 .hint {
   color: var(--color-table-gray);
@@ -597,10 +554,11 @@ header {
   color: var(--color-gray);
   font-style: italic;
 }
-.vflex {
+.ralign {
-  display: flex;
+  text-align: right;
-  gap: 0.8em;
+}
-  flex-direction: column;
+.rextend {
+  margin-right: auto;
 }
 
 
@@ -647,7 +605,7 @@ summary::marker {
 }
 /* NOTE: use `details[open]::details-content` once widely available. */
 details[open] ul {
-  background: white;
+  background-color: white;
   border: 1px solid var(--color-border-gray);
   border-radius: 0.25em;
   box-shadow: 1px 1px 3px var(--color-border-gray);
@@ -670,11 +628,6 @@ li input[type=checkbox] {
 li::marker {
   content: '';
 }
-
-#measurement_form {
-  min-width: 66%;
-  width: max-content;
-}
 /*
  * TODO:
  * * disable <label> containing disabled checkbox: `label:has(input[disabled])`,
@@ -682,3 +635,8 @@ li::marker {
  * * focused label styling (currently only checkbox has focus),
  * * disabled checkbox blue square focus removal.
  * */
+
+#measurement_form {
+  min-width: 66%;
+  width: max-content;
+}

app/controllers/quantities_controller.rb

@@ -8,6 +8,10 @@ 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/helpers/application_helper.rb

@@ -86,6 +86,7 @@ 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|

app/models/quantity.rb

@@ -1,9 +1,10 @@
 class Quantity < ApplicationRecord
-  ATTRIBUTES = [:name, :description, :parent_id]
+  ATTRIBUTES = [:name, :description, :parent_id, :default_unit_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]
+  ATTRIBUTES = [:quantity_id, :value, :unit_id, :taken_at]
 
   belongs_to :user
   belongs_to :quantity

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

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

app/views/layouts/application.html.erb

@@ -23,10 +23,10 @@
   </head>
 
   <body>
-    <header class="hflex">
+    <header class="flex">
       <%= image_link_to t(".source_code"), "code-braces", source_code_url %>
       <%= image_link_to t(".issue_tracker"), "bug-outline", issue_tracker_url,
-            class: "extendedright" %>
+        class: "rextend" %>
       <% if user_signed_in? %>
         <%= image_link_to_unless_current(current_user, "account-wrench-outline",
           edit_user_registration_path) %>

app/views/measurements/_form.html.erb

@@ -1,14 +1,14 @@
 <%= tabular_form_with model: Measurement.new, id: :measurement_form,
-  class: 'topside-area vflex centered',
+  class: 'topside-area flex vertical center',
   html: {onkeydown: 'formProcessKey(event)'} do |form| %>
 
-  <table class="items-table centered">
+  <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="number">
+          <td colspan="3" class="ralign">
-            <%= form.datetime_field :taken_at, required: true %>
+            <%= form.datetime_field :taken_at, required: true, value: Time.current.strftime('%Y-%m-%dT%H:%M') %>
           </td>
         </tr>
       <% end %>
@@ -16,7 +16,7 @@
   </table>
 
   <%# TODO: right-click selection; unnecessary with hierarchical tags? %>
-  <details id="quantity_select" class="centered hexpand" open
+  <details id="quantity_select" class="center hexpand" open
            onkeydown="detailsProcessKey(event)">
     <summary autofocus>
       <!-- TODO: Set content with CSS when span empty to avoid duplication -->
@@ -30,7 +30,7 @@
     <ul><%= quantities_check_boxes(@quantities) %></ul>
   </details>
 
-  <div class="hflex reverse">
+  <div class="flex reverse">
     <%= form.button id: :create_measurement_button, disabled: true -%>
     <%= image_link_to t(:cancel), "close-outline", measurements_path, name: :cancel,
       class: 'dangerous', onclick: render_turbo_stream('form_close') %>

app/views/quantities/_form.html.erb

@@ -8,8 +8,13 @@
     <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="actions">
+    <td class="flex">
       <%= 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

@@ -5,14 +5,15 @@
            data: {drag_path: reparent_quantity_path(quantity), drop_id: dom_id(quantity),
                   drop_id_param: "quantity[parent_id]"} do %>
 
-  <td class="link" style="--depth:<%= quantity.depth %>">
+  <td style="--depth:<%= quantity.depth %>">
-    <%= link_to quantity, edit_quantity_path(quantity), onclick: 'this.blur();',
+    <%= link_to quantity, edit_quantity_path(quantity), class: 'link',
-      data: {turbo_stream: true} %>
+      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="actions">
+    <td class="flex">
       <%= 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

@@ -15,7 +15,8 @@
   <thead>
     <tr>
       <th><%= Quantity.human_attribute_name(:name) %></th>
-      <th><%= Quantity.human_attribute_name(:description) %></th>
+      <th class="hexpand"><%= Quantity.human_attribute_name(:description) %></th>
+      <th><%= Quantity.human_attribute_name(:default_unit) %></th>
       <% if current_user.at_least(:active) %>
         <th><%= t :actions %></th>
         <th></th>
@@ -25,7 +26,7 @@
                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="4"><%= t '.top_level_drop' %></th>
+      <th colspan="5"><%= t '.top_level_drop' %></th>
     <% end %>
   </thead>
   <tbody id="quantities">

app/views/readouts/_form.html.erb

@@ -4,18 +4,25 @@
     <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.hidden_field :quantity_id %>
       <%= form.collection_select :unit_id, @user_units, :id,
         ->(u){ sanitize('&emsp;' * (u.base_id ? 1 : 0) + u.symbol) },
-        {prompt: '', disabled: '', selected: ''}, required: true %>
+        {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="actions">
+    <td class="flex">
       <%# 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} %>

app/views/units/_form.html.erb

@@ -8,11 +8,11 @@
     <td>
       <%= form.text_area :description, cols: 30, rows: 1, escape: false %>
     </td>
-    <td class="number">
+    <td>
       <%= form.number_field :multiplier, required: true, size: 10, min: :step if @unit.base_id? %>
     </td>
 
-    <td class="actions">
+    <td class="flex">
       <%= 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

@@ -6,14 +6,15 @@
                   drop_id: dom_id(unit.base || unit),
                   drop_id_param: "unit[base_id]"} do %>
 
-  <td class="link" style="--depth:<%= unit.base_id? ? 1 : 0 %>">
+  <td style="--depth:<%= unit.base_id? ? 1 : 0 %>">
-    <%= link_to unit, edit_unit_path(unit), onclick: 'this.blur();', data: {turbo_stream: true} %>
+    <%= link_to unit, edit_unit_path(unit), class: 'link', onclick: 'this.blur();',
+      data: {turbo_stream: true} %>
   </td>
   <td><%= unit.description %></td>
-  <td class="number"><%= unit.multiplier.to_html %></td>
+  <td class="ralign"><%= unit.multiplier.to_html %></td>
 
   <% if current_user.at_least(:active) %>
-    <td class="actions">
+    <td class="flex">
       <% 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

@@ -14,7 +14,7 @@
   <thead>
     <tr>
       <th><%= Unit.human_attribute_name(:symbol) %></th>
-      <th><%= Unit.human_attribute_name(:description) %></th>
+      <th class="hexpand"><%= 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

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

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

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

config/environments/test.rb

@@ -58,4 +58,7 @@ 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

@@ -11,8 +11,13 @@ 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
@@ -81,6 +86,9 @@ en:
       revert: Revert
       sign_out: Sign out
       source_code: Get code
+  readouts:
+    form:
+      set_default_unit: Set as default unit
   measurements:
     navigation: Measurements
     no_items: There are no measurements taken. You can Add some now.
@@ -89,6 +97,15 @@ en:
       taken_at_html: Measurement taken at 
     index:
       new_measurement: Add measurement
+    readout:
+      destroy: Delete
+    create:
+      success:
+        one: Recorded 1 measurement.
+        other: Recorded %{count} measurements.
+      no_readouts: No readouts selected.
+    destroy:
+      success: Measurement deleted.
   quantities:
     navigation: Quantities
     no_items: There are no configured quantities. You can Add some or Import from defaults.

db/migrate/20260402000000_add_taken_at_to_readouts.rb

@@ -0,0 +1,6 @@
+class AddTakenAtToReadouts < ActiveRecord::Migration[7.2]
+  def change
+    add_column :readouts, :taken_at, :datetime
+    add_index :readouts, [:user_id, :taken_at]
+  end
+end

db/migrate/20260403000000_add_default_unit_to_quantities.rb

@@ -0,0 +1,5 @@
+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: 2025_01_21_230456) do
+ActiveRecord::Schema[7.2].define(version: 2026_04_03_000000) 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
@@ -20,6 +20,8 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) 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"
@@ -32,10 +34,12 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) 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"
     t.index ["user_id"], name: "index_readouts_on_user_id"
+    t.index ["user_id", "taken_at"], name: "index_readouts_on_user_id_and_taken_at"
   end
 
   create_table "units", charset: "utf8mb4", collation: "utf8mb4_0900_as_ci", force: :cascade do |t|
@@ -70,6 +74,7 @@ ActiveRecord::Schema[7.2].define(version: 2025_01_21_230456) 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/system/quantities_test.rb

@@ -0,0 +1,45 @@
+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