diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..f15441a
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..32c4dfc
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,7 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly
+    open-pull-requests-limit: 5
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..d540082
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  checks:
+    name: Static site checks
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v7
+      - name: Setup Node
+        uses: actions/setup-node@v7
+        with:
+          node-version: 22
+      - name: JavaScript syntax check
+        run: node --check app.js
+      - name: HTML validation
+        run: npx --yes html-validate@11.16.2 index.html
+      - name: Required assets exist
+        run: |
+          status=0
+          for f in index.html styles.css app.js .nojekyll; do
+            if [ ! -f "$f" ]; then echo "::error::missing required file: $f"; status=1; fi
+          done
+          exit $status
diff --git a/.github/workflows/deploy-pages.yml b/.github/workflows/deploy-pages.yml
index 86bcfba..67083c2 100644
--- a/.github/workflows/deploy-pages.yml
+++ b/.github/workflows/deploy-pages.yml
@@ -22,13 +22,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v7
       - name: Setup Pages
-        uses: actions/configure-pages@v5
+        uses: actions/configure-pages@v6
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v5
         with:
           path: .
+          include-hidden-files: true
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5
diff --git a/index.html b/index.html
index 0b265a3..70193ae 100644
--- a/index.html
+++ b/index.html
@@ -1,4 +1,4 @@
-<!doctype html>
+<!DOCTYPE html>
 <html lang="en">
 <head>
   <meta charset="UTF-8">
@@ -20,14 +20,14 @@
       </a>
       <p class="sidebar-kicker">A calmer way to remember<br>what is still in motion.</p>
       <nav class="nav" aria-label="Main navigation">
-        <button class="nav-item is-active" data-view="all"><span class="nav-icon">◌</span>All follow-ups <span class="nav-count" id="all-count">0</span></button>
-        <button class="nav-item" data-view="due"><span class="nav-icon">◷</span>Due soon <span class="nav-count" id="due-count">0</span></button>
-        <button class="nav-item" data-view="waiting"><span class="nav-icon">○</span>Waiting on others <span class="nav-count" id="waiting-count">0</span></button>
-        <button class="nav-item" data-view="done"><span class="nav-icon">✓</span>Closed loop <span class="nav-count" id="done-count">0</span></button>
+        <button class="nav-item is-active" data-view="all" type="button"><span class="nav-icon">◌</span>All follow-ups <span class="nav-count" id="all-count">0</span></button>
+        <button class="nav-item" data-view="due" type="button"><span class="nav-icon">◷</span>Due soon <span class="nav-count" id="due-count">0</span></button>
+        <button class="nav-item" data-view="waiting" type="button"><span class="nav-icon">○</span>Waiting on others <span class="nav-count" id="waiting-count">0</span></button>
+        <button class="nav-item" data-view="done" type="button"><span class="nav-icon">✓</span>Closed loop <span class="nav-count" id="done-count">0</span></button>
       </nav>
       <div class="sidebar-bottom">
         <div class="privacy-note"><span class="lock-icon">⌑</span><div><strong>Private by default</strong><p>Your board stays in this browser.</p></div></div>
-        <div class="sidebar-actions"><button class="text-button" id="export-button">Export</button><button class="text-button" id="import-button">Import</button><input type="file" id="import-input" accept="application/json" hidden></div>
+        <div class="sidebar-actions"><button class="text-button" id="export-button" type="button">Export</button><button class="text-button" id="import-button" type="button">Import</button><input type="file" id="import-input" accept="application/json" hidden></div>
         <p class="version">NUDGEBOARD / 01</p>
       </div>
     </aside>
@@ -40,15 +40,15 @@
 
       <section class="hero">
         <div><p class="eyebrow">Your open loops</p><h1>Keep the loop<br><em>moving.</em></h1></div>
-        <div class="hero-copy"><p>Capture the things you are waiting on, then give them a gentle next nudge. Less mental juggling. More forward motion.</p><button class="primary-button" id="add-button"><span>+</span> Add a follow-up</button></div>
+        <div class="hero-copy"><p>Capture the things you are waiting on, then give them a gentle next nudge. Less mental juggling. More forward motion.</p><button class="primary-button" id="add-button" type="button"><span>+</span> Add a follow-up</button></div>
       </section>
 
       <section class="board-section" aria-label="Follow-ups">
-        <div class="section-heading"><div><h2 id="view-title">All follow-ups</h2><p id="view-subtitle">Everything still in motion.</p></div><div class="board-tools"><label class="search-box"><span aria-hidden="true">⌕</span><input id="search-input" type="search" placeholder="Search follow-ups" aria-label="Search follow-ups"><button class="clear-search" id="clear-search" type="button" aria-label="Clear search" hidden>×</button></label><button class="filter-button" id="filter-button" type="button" aria-expanded="false">Filter <span id="filter-label">all</span> <span aria-hidden="true">⌄</span></button></div></div>
-        <div class="filter-menu" id="filter-menu" hidden><button data-filter="all" class="is-selected">All types</button><button data-filter="people">People</button><button data-filter="work">Work</button><button data-filter="life">Life admin</button></div>
+        <div class="section-heading"><div><h2 id="view-title">All follow-ups</h2><p id="view-subtitle">Everything still in motion.</p></div><div class="board-tools"><div class="search-box"><span aria-hidden="true">⌕</span><input id="search-input" type="search" placeholder="Search follow-ups" aria-label="Search follow-ups"><button class="clear-search" id="clear-search" type="button" aria-label="Clear search" hidden>×</button></div><button class="filter-button" id="filter-button" type="button" aria-expanded="false">Filter <span id="filter-label">all</span> <span aria-hidden="true">⌄</span></button></div></div>
+        <div class="filter-menu" id="filter-menu" hidden><button type="button" data-filter="all" class="is-selected">All types</button><button type="button" data-filter="people">People</button><button type="button" data-filter="work">Work</button><button type="button" data-filter="life">Life admin</button></div>
         <div class="list-header"><span>FOLLOW-UP</span><span>NEXT NUDGE</span><span>STATUS</span><span></span></div>
         <div class="follow-up-list" id="follow-up-list"></div>
-        <div class="empty-state" id="empty-state" hidden><div class="empty-icon">↗</div><h3 id="empty-title">Start with one open loop.</h3><p id="empty-copy">Capture the next reply, decision, or errand you do not want to keep carrying in your head.</p><button class="secondary-button" id="empty-add-button">Add a follow-up</button></div>
+        <div class="empty-state" id="empty-state" hidden><div class="empty-icon">↗</div><h3 id="empty-title">Start with one open loop.</h3><p id="empty-copy">Capture the next reply, decision, or errand you do not want to keep carrying in your head.</p><button class="secondary-button" id="empty-add-button" type="button">Add a follow-up</button></div>
       </section>
       <footer class="main-footer"><span>Made for the things that fall between the cracks.</span><span><kbd>N</kbd> new follow-up</span></footer>
     </main>
@@ -57,9 +57,9 @@
   <dialog class="modal" id="follow-up-modal">
     <form method="dialog" id="follow-up-form">
       <div class="modal-header"><div><p class="eyebrow" id="modal-eyebrow">New open loop</p><h2 id="modal-title">Add a follow-up</h2></div><button class="close-button" id="close-modal" type="button" aria-label="Close">×</button></div>
-      <label class="field-label" for="title-input">What are you waiting on?<input id="title-input" name="title" required maxlength="100" placeholder="e.g. Jamie to send the revised quote"></label>
-      <div class="form-grid"><label class="field-label" for="person-input">Person or place<input id="person-input" name="person" maxlength="60" placeholder="e.g. Jamie · Acme Co."></label><label class="field-label" for="date-input">Nudge on<input id="date-input" name="date" type="date" required></label></div>
-      <div class="form-grid"><label class="field-label" for="category-input">Area<select id="category-input" name="category"><option value="people">People</option><option value="work">Work</option><option value="life">Life admin</option></select></label><label class="field-label" for="note-input">Context <span>(optional)</span><input id="note-input" name="note" maxlength="120" placeholder="What is the next small move?"></label></div>
+      <label class="field-label">What are you waiting on?<input id="title-input" name="title" type="text" required maxlength="100" placeholder="e.g. Jamie to send the revised quote"></label>
+      <div class="form-grid"><label class="field-label">Person or place<input id="person-input" name="person" type="text" maxlength="60" placeholder="e.g. Jamie · Acme Co."></label><label class="field-label">Nudge on<input id="date-input" name="date" type="date" required></label></div>
+      <div class="form-grid"><label class="field-label">Area<select id="category-input" name="category"><option value="people">People</option><option value="work">Work</option><option value="life">Life admin</option></select></label><label class="field-label">Context <span>(optional)</span><input id="note-input" name="note" type="text" maxlength="120" placeholder="What is the next small move?"></label></div>
       <div class="modal-actions"><button class="secondary-button" id="cancel-modal" type="button">Cancel</button><button class="primary-button" id="save-button" type="submit">Save follow-up</button></div>
     </form>
   </dialog>