diff --git a/internal/check-optional-t-equivalence.mjs b/internal/check-optional-t-equivalence.mjs
index a38f03d54..e96e2f648 100644
--- a/internal/check-optional-t-equivalence.mjs
+++ b/internal/check-optional-t-equivalence.mjs
@@ -129,6 +129,12 @@ const SITES = [
   // as a semantic conflict on main before it landed. The row asserts the '' explicitly so a later
   // edit cannot quietly re-add a namespace.
   ['plugin-designs/gospel-resources/resources-map.vue',  "useOptionalT(''", null],
+  // wave 3b — cities-internet. All three were byte-identical in the guard block; each keeps its own
+  // enLookup fallback, so a bare host renders the same English. Their local fill() used `k in params`,
+  // so the shared fillParams also removes a way for them to print the literal "null".
+  ['plugin-designs/cities-internet/connectivity-list.vue', 'useOptionalT', 'fallback: enLookup'],
+  ['plugin-designs/cities-internet/connectivity-map.vue',  'useOptionalT', 'fallback: enLookup'],
+  ['plugin-designs/cities-internet/data-tables.vue',       'useOptionalT', 'fallback: enLookup'],
 ]
 // ★ ONE FILE KEEPS TWO BARE useI18n CALLS ON PURPOSE, and the count is asserted rather than waived.
 // resources-map.vue reads the LOCALE twice (`useI18n().locale.value`) to decide isEnglish and the
diff --git a/plugin-designs/cities-internet/connectivity-list.vue b/plugin-designs/cities-internet/connectivity-list.vue
index d16ef19ca..3ee15a021 100644
--- a/plugin-designs/cities-internet/connectivity-list.vue
+++ b/plugin-designs/cities-internet/connectivity-list.vue
@@ -34,7 +34,7 @@
 import { computed, inject, ref } from 'vue'
 import { useShadowStyles } from '@map/composables/useShadowStyles.js'
 import data from './data/connectivity.json'
-import { useI18n } from 'vue-i18n'
+import { useOptionalT } from '@map/composables/useOptionalT.js'
 import enConnectivity from '@map/i18n/locales/en/connectivity.json'
 
 const profileConfig = inject('profileConfig', ref(null))
@@ -44,12 +44,14 @@ const profileConfig = inject('profileConfig', ref(null))
 // shipped catalog is the fallback, never a blank or a key. Region and country names are data.
 const enLookup = (key) =>
   String(key).replace(/^connectivity\./, '').split('.').reduce((o, k) => (o == null ? o : o[k]), enConnectivity)
-const fill = (str, params) => (params ? String(str).replace(/\{(\w+)\}/g, (m, k) => (k in params ? params[k] : m)) : str)
-let t = (key, params) => fill(enLookup(key) ?? String(key), params)
-try {
-  const i18n = useI18n()
-  t = (key, params) => { const v = i18n.t(key, params || {}); return v === key ? fill(enLookup(key) ?? key, params) : v }
-} catch (_) { /* no i18n on this host: the English catalog above is the fallback */ }
+// C4 wave 3b: the guard is library/composables/useOptionalT.js now. enLookup STAYS as the fallback,
+// passed in, so a bare host renders the same ENGLISH it always did. gospel-plugin chose the
+// locale-honouring catalogue default for their bundle instead ("a partner host that never installed
+// vue-i18n serves its readers English while the bundle already carries all 11 catalogues"); the same
+// choice is open to cities-internet's owner and is one word to make — it is not a migration's to take.
+// The local fill() is gone with the guard: fillParams applies the same interpolation, except it leaves
+// a placeholder for a NULL value where this fill() rendered the string "null".
+const t = useOptionalT('connectivity', { fallback: enLookup })
 // NUMERALS ARE HELD for the Driver (dx-shepherd, 2026-09-26): a locale-following format would switch
 // 'ar' to Arabic-Indic digits. Until that is decided, numbers keep the browser-default format they
 // had before this pass; only the TEXT is translated.
diff --git a/plugin-designs/cities-internet/connectivity-map.vue b/plugin-designs/cities-internet/connectivity-map.vue
index 4745f3540..fc79afaea 100644
--- a/plugin-designs/cities-internet/connectivity-map.vue
+++ b/plugin-designs/cities-internet/connectivity-map.vue
@@ -33,7 +33,7 @@
  * carrier flag is a NAME-PATTERN HEURISTIC, not a verified classification.
  */
 import { computed, inject, ref, shallowRef, markRaw, onMounted, onBeforeUnmount } from 'vue'
-import { useI18n } from 'vue-i18n'
+import { useOptionalT } from '@map/composables/useOptionalT.js'
 import enConnectivity from '@map/i18n/locales/en/connectivity.json'
 import { useShadowStyles } from '@map/composables/useShadowStyles.js'
 import { addMapAttribution } from '@map/composables/useMapAttribution'
@@ -208,12 +208,14 @@ function paintGroups(map) {
 // Carrier and platform names are data and are not translated.
 const enLookup = (key) =>
   String(key).replace(/^connectivity\./, '').split('.').reduce((o, k) => (o == null ? o : o[k]), enConnectivity)
-const fill = (str, params) => (params ? String(str).replace(/\{(\w+)\}/g, (m, k) => (k in params ? params[k] : m)) : str)
-let t = (key, params) => fill(enLookup(key) ?? String(key), params)
-try {
-  const i18n = useI18n()
-  t = (key, params) => { const v = i18n.t(key, params || {}); return v === key ? fill(enLookup(key) ?? key, params) : v }
-} catch (_) { /* no i18n on this host: the English catalog above is the fallback */ }
+// C4 wave 3b: the guard is library/composables/useOptionalT.js now. enLookup STAYS as the fallback,
+// passed in, so a bare host renders the same ENGLISH it always did. gospel-plugin chose the
+// locale-honouring catalogue default for their bundle instead ("a partner host that never installed
+// vue-i18n serves its readers English while the bundle already carries all 11 catalogues"); the same
+// choice is open to cities-internet's owner and is one word to make — it is not a migration's to take.
+// The local fill() is gone with the guard: fillParams applies the same interpolation, except it leaves
+// a placeholder for a NULL value where this fill() rendered the string "null".
+const t = useOptionalT('connectivity', { fallback: enLookup })
 
 // Bands, not a continuous ramp: a reader can hold four categories, not a gradient.
 const BANDS = [
diff --git a/plugin-designs/cities-internet/data-tables.vue b/plugin-designs/cities-internet/data-tables.vue
index fd1265b3d..74bd0be27 100644
--- a/plugin-designs/cities-internet/data-tables.vue
+++ b/plugin-designs/cities-internet/data-tables.vue
@@ -25,7 +25,7 @@ import { computed, inject, ref, watch } from 'vue'
 import DataTable from '@map/components/tables/DataTable.vue'
 import { useShadowStyles } from '@map/composables/useShadowStyles.js'
 import { resolveAssetsBase } from '@map/utils/embedBase.js'
-import { useI18n } from 'vue-i18n'
+import { useOptionalT } from '@map/composables/useOptionalT.js'
 import enConnectivity from '@map/i18n/locales/en/connectivity.json'
 
 
@@ -38,12 +38,14 @@ const assetsBase = computed(() => resolveAssetsBase(profileConfig.value))
 // shipped catalog is the fallback, never a blank or a key. Region and country names are data.
 const enLookup = (key) =>
   String(key).replace(/^connectivity\./, '').split('.').reduce((o, k) => (o == null ? o : o[k]), enConnectivity)
-const fill = (str, params) => (params ? String(str).replace(/\{(\w+)\}/g, (m, k) => (k in params ? params[k] : m)) : str)
-let t = (key, params) => fill(enLookup(key) ?? String(key), params)
-try {
-  const i18n = useI18n()
-  t = (key, params) => { const v = i18n.t(key, params || {}); return v === key ? fill(enLookup(key) ?? key, params) : v }
-} catch (_) { /* no i18n on this host: the English catalog above is the fallback */ }
+// C4 wave 3b: the guard is library/composables/useOptionalT.js now. enLookup STAYS as the fallback,
+// passed in, so a bare host renders the same ENGLISH it always did. gospel-plugin chose the
+// locale-honouring catalogue default for their bundle instead ("a partner host that never installed
+// vue-i18n serves its readers English while the bundle already carries all 11 catalogues"); the same
+// choice is open to cities-internet's owner and is one word to make — it is not a migration's to take.
+// The local fill() is gone with the guard: fillParams applies the same interpolation, except it leaves
+// a placeholder for a NULL value where this fill() rendered the string "null".
+const t = useOptionalT('connectivity', { fallback: enLookup })
 // NUMERALS ARE HELD for the Driver (dx-shepherd, 2026-09-26): a locale-following format would switch
 // 'ar' to Arabic-Indic digits. Until that is decided, numbers keep the browser-default format they
 // had before this pass; only the TEXT is translated.
diff --git a/plugin-designs/regions-dashboard/scripts/strip-code.mjs b/plugin-designs/regions-dashboard/scripts/strip-code.mjs
index a3da12eb3..50456fbb3 100644
--- a/plugin-designs/regions-dashboard/scripts/strip-code.mjs
+++ b/plugin-designs/regions-dashboard/scripts/strip-code.mjs
@@ -21,6 +21,16 @@
 //
 // Comments are replaced by SPACES, preserving length and line structure, so line numbers reported
 // against the result still point at the real file.
+// ★ WHAT THIS DOES NOT STRIP, and both gaps have already cost a real measurement:
+//   - CSS comments inside a JS TEMPLATE LITERAL. A string is copied through verbatim, correctly for
+//     JS, but useShadowStyles(`...`) contains CSS whose /* */ the BROWSER honours. Reading specificity
+//     off such a file once gave (0,5,53) because a comment landed inside the selector.
+//   - HTML comments in a .vue TEMPLATE. `<!-- ... -->` is invisible here, so any identifier quoted in
+//     one is counted as code. That made a bare-useI18n census read 3 where the code had 2.
+// gospel-plugin's generalisation, worth keeping: "any <!-- --> in a template that quotes an identifier
+// will keep doing that to you". THE RULE: the stripper must match the LANGUAGE of the text being read.
+// For a .vue file, strip HTML comments first, then call this for the script block.
+
 export function codeOnly(src) {
   let out = ''
   let i = 0