diff --git a/.github/workflows/js-tests.yml b/.github/workflows/js-tests.yml
new file mode 100644
index 0000000..3d1fb9c
--- /dev/null
+++ b/.github/workflows/js-tests.yml
@@ -0,0 +1,18 @@
+name: JavaScript tests
+
+on:
+  push:
+    branches: [develop]
+
+  pull_request:
+    branches: [develop, main]
+
+jobs:
+  node-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "24"
+      - run: node --test "tests/js/*.test.mjs"
diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
new file mode 100644
index 0000000..a9c3fc2
--- /dev/null
+++ b/.github/workflows/python-tests.yml
@@ -0,0 +1,20 @@
+name: Python tests
+
+on:
+  push:
+    branches: [develop]
+
+  pull_request:
+    branches: [develop, main]
+
+jobs:
+  pytest:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+          cache: pip
+      - run: pip install -r requirements.txt
+      - run: python -m pytest tests -q
diff --git a/js/tool.js b/js/tool.js
index 92831d6..189a0d2 100644
--- a/js/tool.js
+++ b/js/tool.js
@@ -57,7 +57,7 @@ function onEnter(step) {
   if (step === STEP.ALPHA) refit();
   else if (step === STEP.SCATTER) renderScatter(false);
   else if (step === STEP.FIT) renderScatter(true);
-  else if (step === STEP.ODYSSEY) updateOdyssey();
+  else if (step === STEP.ODYSSEY) enterOdyssey();
 }
 
 function refit() {
@@ -136,12 +136,25 @@ function refreshGate() {
 
 /* ── Step 5: Odyssey sliders ── */
 function buildSliders() {
-  const fabula = document.getElementById("fabulaSlider");
-  const syuzhet = document.getElementById("syuzhetSlider");
-  fabula.value = pipeline.odyssey.fabula;
-  syuzhet.value = pipeline.odyssey.syuzhet;
-  fabula.addEventListener("input", updateOdyssey);
-  syuzhet.addEventListener("input", updateOdyssey);
+  document.getElementById("fabulaSlider").addEventListener("input", updateOdyssey);
+  document.getElementById("syuzhetSlider").addEventListener("input", updateOdyssey);
+}
+
+// Cached per fit: invalidated with `personal` whenever ratings change.
+function optimalFor(p) {
+  return (p.optimal ??= computeOptimal(p));
+}
+
+function enterOdyssey() {
+  if (!personal) refit();
+  // Seed the sliders with this person's ideal — the same values the share
+  // card shows. Once seeded for a given fit, keep their manual tweaks.
+  if (!personal.optimal) {
+    const optimal = optimalFor(personal);
+    document.getElementById("fabulaSlider").value = optimal.fabula;
+    document.getElementById("syuzhetSlider").value = optimal.syuzhet;
+  }
+  updateOdyssey();
 }
 
 function updateOdyssey() {
@@ -191,7 +204,7 @@ function initShare() {
 
 async function openShare() {
   if (!personal) refit();
-  const optimal = computeOptimal(personal);
+  const optimal = optimalFor(personal);
   const counts = oscarCounts(pipeline.oscars.coeffs, optimal.fabula, optimal.syuzhet);
 
   const canvas = document.createElement("canvas");
diff --git a/src/plotting/style.py b/src/plotting/style.py
index 35ccf1a..1fb1058 100644
--- a/src/plotting/style.py
+++ b/src/plotting/style.py
@@ -18,6 +18,7 @@
 GREEN_LIGHT = "#89dd9d"
 RUST        = "#c4694d"
 RUST_DARK   = "#a3502e"
+GOLD        = "#d4a017"
 GRID        = "#d8d8d8"
 BORDER      = "#cccccc"
 INK         = "#1a1a1a"
@@ -109,6 +110,15 @@ def fit_line(ax, x, y, color: str = RUST, label: str = None, **kwargs):
     return ax.plot(x, y, **defaults)
 
 
+def equation_box(ax, text: str):
+    """Small italic caption describing the fit, boxed to match the panel."""
+    return ax.text(0.03, 0.95, text, transform=ax.transAxes,
+                   fontsize=11, style="italic", fontfamily=FONT_SERIF,
+                   color=INK, ha="left", va="top",
+                   bbox=dict(boxstyle="round,pad=0.45", facecolor=BG,
+                             edgecolor=BORDER, alpha=0.9))
+
+
 def add_legend(ax):
     """Legend styled to match the panel."""
     leg = ax.legend(fontsize=11.5, loc="lower left",
diff --git a/tests/js/share.test.mjs b/tests/js/share.test.mjs
index f437da6..57bda97 100644
--- a/tests/js/share.test.mjs
+++ b/tests/js/share.test.mjs
@@ -38,6 +38,18 @@ test("returned rating matches predictAt at the returned point", () => {
   assert.equal(opt.rating, predictAt(p, opt.fabula, opt.syuzhet));
 });
 
+test("the optimum lands on the sliders' grid (0..10, step 0.1)", () => {
+  // tool.js seeds the range inputs with these values, so they must be
+  // in-range multiples of the 0.1 step or the browser would clamp/snap them
+  for (const coeffs of [[0.25, 0.5], [-0.25, 4.5], [-0.1, 1.2, 1.0]]) {
+    const opt = computeOptimal(personal(coeffs));
+    for (const v of [opt.fabula, opt.syuzhet]) {
+      assert.ok(v >= 0 && v <= 10, `${v} out of range`);
+      assert.ok(Math.abs(v * 10 - Math.round(v * 10)) < 1e-9, `${v} off-grid`);
+    }
+  }
+});
+
 test("the card URL is the real domain", () => {
   assert.equal(SITE_URL, "willtheodysseybegood.com");
 });
diff --git a/tool.html b/tool.html
index 46cb6e3..90e64c5 100644
--- a/tool.html
+++ b/tool.html
@@ -120,7 +120,8 @@ <h1>The vision emerges</h1>
     <div class="step-inner">
       <h1>The Odyssey <span class="year">(2026)</span></h1>
       <p class="step-lede">
-        Use the sliders to see how you'll like The Odyssey at different
+        The sliders start at your ideal scores for fabula and syuzhet.
+        Drag them around to see how you'll like The Odyssey at different
         degrees of insanity.
       </p>