diff --git a/src/__tests__/retired-route-links-guard.test.ts b/src/__tests__/retired-route-links-guard.test.ts
index b5d11d6d5..874c20989 100644
--- a/src/__tests__/retired-route-links-guard.test.ts
+++ b/src/__tests__/retired-route-links-guard.test.ts
@@ -24,6 +24,11 @@ function walk(dir: string): string[] {
   });
 }
 
+/** Every regex metacharacter escaped, the backslash included. */
+function escapeRegExp(text: string): string {
+  return text.replace(/[\\^$.*+?()[\]{}|/]/g, "\\$&");
+}
+
 describe("no link targets a retired route", () => {
   const files = walk(join(ROOT, "src"));
 
@@ -33,7 +38,7 @@ describe("no link targets a retired route", () => {
 
   it.each(Object.entries(RETIRED))("%s is linked as %s", (route) => {
     const pattern = new RegExp(
-      `(?:href|push|replace)[=(]\\s*\\{?\\s*["'\`]${route.replace(/\//g, "\\/")}["'\`?#]`,
+      `(?:href|push|replace)[=(]\\s*\\{?\\s*["'\`]${escapeRegExp(route)}["'\`?#]`,
     );
     const offenders = files
       .filter((file) => pattern.test(readFileSync(file, "utf8")))
diff --git a/src/components/day/__tests__/use-day-value-format.test.tsx b/src/components/day/__tests__/use-day-value-format.test.tsx
index 7fbca9381..e7f1722b4 100644
--- a/src/components/day/__tests__/use-day-value-format.test.tsx
+++ b/src/components/day/__tests__/use-day-value-format.test.tsx
@@ -42,22 +42,38 @@ function Probe({
   );
 }
 
+/**
+ * The text of rendered markup: every character outside a `<…>` tag. A walk
+ * rather than a tag-stripping regex, which can leave a tag behind when one
+ * is split across another.
+ */
+function textOf(html: string): string {
+  let out = "";
+  let inTag = false;
+  for (const ch of html) {
+    if (ch === "<") inTag = true;
+    else if (ch === ">") inTag = false;
+    else if (!inTag) out += ch;
+  }
+  return out;
+}
+
 function read(
   type: string,
   value: number,
   unit: string,
   locale: "en" | "de" = "en",
 ) {
-  return renderToStaticMarkup(
-    <I18nProvider
-      initialLocale={locale}
-      initialMessages={locale === "de" ? deMessages : enMessages}
-    >
-      <Probe type={type} value={value} unit={unit} />
-    </I18nProvider>,
-  )
-    .replace(/<[^>]+>/g, "")
-    .replace(/<!-- -->/g, "");
+  return textOf(
+    renderToStaticMarkup(
+      <I18nProvider
+        initialLocale={locale}
+        initialMessages={locale === "de" ? deMessages : enMessages}
+      >
+        <Probe type={type} value={value} unit={unit} />
+      </I18nProvider>,
+    ),
+  );
 }
 
 describe("a day's values in their charts' spelling", () => {
diff --git a/src/components/insights/__tests__/health-score-card.test.tsx b/src/components/insights/__tests__/health-score-card.test.tsx
index e27243b14..710eef051 100644
--- a/src/components/insights/__tests__/health-score-card.test.tsx
+++ b/src/components/insights/__tests__/health-score-card.test.tsx
@@ -48,6 +48,22 @@ const coverage = {
   missing: ["ACTIVITY", "SLEEP"],
 };
 
+/**
+ * The text of rendered markup: every character outside a `<…>` tag. A walk
+ * rather than a tag-stripping regex, which can leave a tag behind when one
+ * is split across another.
+ */
+function textOf(html: string): string {
+  let out = "";
+  let inTag = false;
+  for (const ch of html) {
+    if (ch === "<") inTag = true;
+    else if (ch === ">") inTag = false;
+    else if (!inTag) out += ch;
+  }
+  return out;
+}
+
 function render(node: React.ReactNode, locale: Locale = "en"): string {
   return renderToStaticMarkup(
     <I18nProvider initialLocale={locale}>{node}</I18nProvider>,
@@ -642,9 +658,7 @@ describe("<HealthScoreCard> composite states", () => {
     // The onset is an instant; it reads as the day it falls on in the
     // profile timezone, in the user's date format, never as raw ISO.
     // v1.42 — the date is a link to its day; the sentence reads the same.
-    expect(rest.replace(/<[^>]+>/g, "")).toMatch(
-      /Rest Mode active since \d{2}\/\d{2}\/2026\./,
-    );
+    expect(textOf(rest)).toMatch(/Rest Mode active since \d{2}\/\d{2}\/2026\./);
     expect(rest).not.toContain("T23:30:00");
     expect(rest).toContain('data-slot="health-score-tension"');
     expect(rest).toContain('data-slot="health-score-return-to-band"');
@@ -672,7 +686,7 @@ describe("<HealthScoreCard> composite states", () => {
       />,
     );
     const rest = atRest(html);
-    expect(rest.replace(/<[^>]+>/g, "")).toMatch(
+    expect(textOf(rest)).toMatch(
       /Rest Mode active since (07\/20\/2026|20\/07\/2026)/,
     );
     // The date opens the day it names, in the profile timezone.
diff --git a/src/lib/pwa/theme-color.ts b/src/lib/pwa/theme-color.ts
index 3e8ca8eda..9976c2278 100644
--- a/src/lib/pwa/theme-color.ts
+++ b/src/lib/pwa/theme-color.ts
@@ -35,7 +35,13 @@ export function applyThemeColor(
  * tags to that theme, which until now waited for hydration: a phone in light
  * mode running the app in dark mode showed a light status bar until React
  * caught up. The tags may stream in after the script, so it repeats the
- * rewrite once the document is parsed. Built from constants only — the
- * layout's one `dangerouslySetInnerHTML` stays file-literal content.
+ * rewrite once the document is parsed.
+ *
+ * One string literal, with the two colours written into it rather than
+ * interpolated from `THEME_COLOR`: the layout's one `dangerouslySetInnerHTML`
+ * then carries file-literal content and nothing is built from a value at
+ * runtime. `theme-color.test.ts` runs the script and compares what it paints
+ * against `THEME_COLOR`, so the copies cannot drift apart unnoticed.
  */
-export const THEME_BOOT_SCRIPT = `(function(){var c="dark";try{var t=localStorage.getItem("healthlog-theme");c=(t==="light"||t==="dark")?t:(t==="system"?(window.matchMedia("(prefers-color-scheme:dark)").matches?"dark":"light"):"dark")}catch(e){}document.documentElement.classList.add(c);var k=c==="light"?${JSON.stringify(THEME_COLOR.light)}:${JSON.stringify(THEME_COLOR.dark)};function m(){var a=document.querySelectorAll('meta[name="theme-color"]');for(var i=0;i<a.length;i++)a[i].setAttribute("content",k)}m();document.addEventListener("DOMContentLoaded",m)})()`;
+export const THEME_BOOT_SCRIPT =
+  '(function(){var c="dark";try{var t=localStorage.getItem("healthlog-theme");c=(t==="light"||t==="dark")?t:(t==="system"?(window.matchMedia("(prefers-color-scheme:dark)").matches?"dark":"light"):"dark")}catch(e){}document.documentElement.classList.add(c);var k=c==="light"?"#f3f2f5":"#282a36";function m(){var a=document.querySelectorAll(\'meta[name="theme-color"]\');for(var i=0;i<a.length;i++)a[i].setAttribute("content",k)}m();document.addEventListener("DOMContentLoaded",m)})()';