diff --git a/gulpfile.js/index.js b/gulpfile.js/index.js
index 81e69f8430..2da39623b6 100644
--- a/gulpfile.js/index.js
+++ b/gulpfile.js/index.js
@@ -459,6 +459,13 @@ const ALLOWED_EXTENSIONS_TO_CACHE = ["js", "html", "htm", "xml", "xhtml", "mjs",
 const DISALLOWED_EXTENSIONS_TO_CACHE = ["map", "nuspec", "partial", "pre", "post",
     "webmanifest", "rb", "ts"];
 
+// Ceiling for the PWA service worker cache, in KB. Dev builds ship unminified sources and keep the
+// phoenix-pro sources in dist, so they are legitimately larger than prod - dev gets the looser
+// limit, mirroring DEV_MAX_TOTAL_SIZE_MB / PROD_MAX_TOTAL_SIZE_MB in validate-build.js. Prod is the
+// number that actually matters for users, so keep that one tight.
+const MAX_CACHE_SIZE_KB_PROD = 78000;
+const MAX_CACHE_SIZE_KB_DEV = 100000;
+
 const EXCLUDE_PATTERNS_FROM_CACHE = [
     /src\/nls\/.*expertTranslations\.json$/,
     /src\/nls\/.*lastTranslated\.json$/,
@@ -512,7 +519,7 @@ function _getFileDetails(path) {
     };
 }
 
-function _computeCacheManifest(baseDir, filePaths) {
+function _computeCacheManifest(baseDir, filePaths, maxSizeKB) {
     let manifest = {}, fileDetails, totalSize = 0;
     let fileSizes = [];
     for(let filePath of filePaths){
@@ -533,8 +540,9 @@ function _computeCacheManifest(baseDir, filePaths) {
 
     totalSize = Math.round(totalSize/1024); // KB
     console.log("Total size of cache in KB: ", totalSize);
-    if(totalSize > 78000){
-        throw new Error("The total size of the src or dist folder core assets exceeds 78MB." +
+    if(totalSize > maxSizeKB){
+        throw new Error(`The total size of the src or dist folder core assets exceeds ` +
+            `${Math.round(maxSizeKB / 1000)}MB (got ${Math.round(totalSize / 1000)}MB).` +
             "\nPlease review and trim storage. This significantly impacts the distribution size." +
             "\nEither trim down the size or increase the limit after careful review.");
     }
@@ -954,24 +962,32 @@ async function _renameConcatExtensionsinDist() {
     }
 }
 
-function createCacheManifest(srcFolder) {
+function createCacheManifest(srcFolder, maxSizeKB) {
     return new Promise((resolve, reject)=>{
         _listFilesInDir(srcFolder).then((files)=>{
             files = _fixAndFilterPaths(srcFolder, files);
             console.log("Files in cache: ", files.length);
-            let cache = _computeCacheManifest(srcFolder, files);
+            let cache = _computeCacheManifest(srcFolder, files, maxSizeKB);
             fs.writeFileSync(srcFolder + "/cacheManifest.json", JSON.stringify(cache, null, 2));
             resolve();
         }).catch(reject);
     });
 }
 
+// src/cacheManifest.json only matters when the src tree itself is served (npm run serve) - releases
+// ship dist/, whose manifest is regenerated by createDistCacheManifest and overwrites the copy that
+// makeDistNonJS carried over. So this is a dev-serving artefact in every chain and takes the dev
+// limit; the shipped artefact is guarded by createDistCacheManifest + validateDistSizeRestrictions.
 function createSrcCacheManifest() {
-    return createCacheManifest("src");
+    return createCacheManifest("src", MAX_CACHE_SIZE_KB_DEV);
 }
 
 function createDistCacheManifest() {
-    return createCacheManifest("dist");
+    return createCacheManifest("dist", MAX_CACHE_SIZE_KB_PROD);
+}
+
+function createDistCacheManifestDev() {
+    return createCacheManifest("dist", MAX_CACHE_SIZE_KB_DEV);
 }
 
 function copyDistToDistTestFolder() {
@@ -1101,7 +1117,7 @@ exports.reset = series(cleanAll);
 
 exports.releaseDev = series(cleanDist, exports.buildDebug, makeBracketsConcatJS, makeConcatExtensions, _compileLessSrc,
     makeDistAll, cleanUnwantedFilesInDistDev, releaseDev, _renameConcatExtensionsinDist,
-    createDistCacheManifest, createDistTest,
+    createDistCacheManifestDev, createDistTest,
     _cleanPhoenixProGitFolder, _cleanReleaseBuildArtefactsInSrc, validateBuild.validateDistSizeRestrictions);
 exports.releaseStaging = series(cleanDist, exports.build, makeBracketsConcatJSWithMinifiedBrowserScripts,
     makeConcatExtensions, _compileLessSrc, makeDistNonJS, makeJSDist, makeJSPrettierDist, makeNonMinifyDist,
diff --git a/tracking-repos.json b/tracking-repos.json
index 79697b8469..f58b097035 100644
--- a/tracking-repos.json
+++ b/tracking-repos.json
@@ -1,5 +1,5 @@
 {
   "phoenixPro": {
-    "commitID": "11fc9899d481d9781b2a8d850d8c7209db4c010a"
+    "commitID": "5886d202574264a2c4c70b4126618b9fae4950ff"
   }
 }