diff --git a/BUILDING.md b/BUILDING.md
index 6e753e2f..32e3d180 100644
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -1176,6 +1176,10 @@ npm run build:ios:prod
     (.../.pkgx/zlib.net/v1.3.0/lib/libz.1.3.dylib) built for 'macOS'` then run
     XCode outside that terminal (ie. not with `npx cap open ios`).
   - Required password entry 26 times.
+  - Before distributing, confirm the archive carries production server
+    defaults. Xcode packages whatever web bundle is in `ios/App/App/public`,
+    even one from a `--test` build:
+    `./scripts/check-prod-bundle.sh ios/App/App/public`
   - Click Distribute -> App Store Connect
 - In AppStoreConnect, add the build to the distribution. You may have to remove
   the current build with the "-" when you hover over it, then "Add Build" with the
@@ -1478,6 +1482,13 @@ cd -
 
 ... and find your `aab` file at app/build/outputs/bundle/release
 
+* Gradle packages whatever web bundle was last synced into
+  `android/app/src/main/assets/public`, even one from a `--test` build. Before
+  uploading, confirm it has production server defaults:
+  `./scripts/check-prod-bundle.sh android/app/build/outputs/bundle/release/app-release.aab`
+* `build-android.sh` runs `./gradlew clean`, which deletes any earlier `aab`, so
+  run `bundleRelease` after the build script finishes.
+
 * Note that F-Droid builds should omit `-PfirebaseEnabled`.
 
 At play.google.com/console:
@@ -2222,6 +2233,8 @@ command chaining, following DRY principles.
 - `7` - Asset generation failed
 - `8` - Android Studio launch failed
 - `9` - Resource check failed
+- `10` - Production bundle has test/dev server defaults (`--prod` only; see
+  `scripts/check-prod-bundle.sh`)
 
 ### A.4 build-ios.sh
 
@@ -2282,6 +2295,8 @@ command chaining, following DRY principles.
 - **Clean Build**: Removes Xcode build artifacts and DerivedData
 - **Asset Generation**: Creates platform-specific assets
 - **Simulator Support**: Launches iOS Simulator for testing
+- **Production Bundle Check**: With `--prod`, exits with code `10` if the synced
+  web bundle has test/dev server defaults (`scripts/check-prod-bundle.sh`)
 
 ### A.5 common.sh
 
diff --git a/package.json b/package.json
index 7df94418..784672be 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "test:prerequisites": "node scripts/check-prerequisites.js",
     "test:unit": "jest",
     "check:dependencies": "./scripts/check-dependencies.sh",
+    "check:prod-bundle": "./scripts/check-prod-bundle.sh",
     "deps:update-daily-notification-plugin": "npm install @timesafari/daily-notification-plugin@git+https://gitea.anomalistdesign.com/trent_larson/daily-notification-plugin.git#master",
     "test:all": "npm run lint && npm run type-check && npm run type-check:vue && npm run test:unit && npm run test:web && npm run test:mobile && echo '\n\n\nGotta add the performance tests'",
     "test:web": "npx playwright test -c playwright.config-local.ts --trace on",
diff --git a/scripts/build-android.sh b/scripts/build-android.sh
index ef048b62..ea0ac10b 100755
--- a/scripts/build-android.sh
+++ b/scripts/build-android.sh
@@ -545,7 +545,7 @@ fi
 # Handle assets-only mode
 if [ "$ASSETS_ONLY" = true ]; then
     log_info "Assets-only mode: generating assets"
-    safe_execute "Generating assets" "npx capacitor-assets generate --android" || exit 7
+    safe_execute "Generating assets" "npx capacitor-assets generate --android --assetPath resources" || exit 7
     log_success "Assets generation completed successfully!"
     exit 0
 fi
@@ -612,25 +612,31 @@ elif [ "$BUILD_MODE" = "production" ]; then
     safe_execute "Building Capacitor version (production)" "npm run build:capacitor -- --mode production" || exit 3
 fi
 
-# Step 6: Clean Gradle build
+# Step 6: Sync with Capacitor (before any Gradle assemble, which packages
+# whatever web bundle and resources are in android/app/src/main at that moment)
+safe_execute "Syncing with Capacitor" "npx cap sync android" || exit 6
+
+# Step 6.5: Restore local plugins (capacitor.plugins.json gets overwritten by cap sync)
+safe_execute "Restoring local plugins" "node scripts/restore-local-plugins.js" || exit 7
+
+# Step 6.6: Verify the synced web bundle has production server defaults
+if [ "$BUILD_MODE" = "production" ]; then
+    safe_execute "Checking production bundle" "./scripts/check-prod-bundle.sh android/app/src/main/assets/public" || exit 10
+fi
+
+# Step 7: Generate assets
+safe_execute "Generating assets" "npx capacitor-assets generate --android --assetPath resources" || exit 7
+
+# Step 8: Clean Gradle build
 safe_execute "Cleaning Gradle build" "cd android && ./gradlew clean && cd .." || exit 4
 
-# Step 7: Build based on type
+# Step 9: Build based on type
 if [ "$BUILD_TYPE" = "debug" ]; then
     safe_execute "Assembling debug build" "cd android && ./gradlew assembleDebug && cd .." || exit 5
 elif [ "$BUILD_TYPE" = "release" ]; then
     safe_execute "Assembling release build" "cd android && ./gradlew assembleRelease && cd .." || exit 5
 fi
 
-# Step 8: Sync with Capacitor
-safe_execute "Syncing with Capacitor" "npx cap sync android" || exit 6
-
-# Step 8.5: Restore local plugins (capacitor.plugins.json gets overwritten by cap sync)
-safe_execute "Restoring local plugins" "node scripts/restore-local-plugins.js" || exit 7
-
-# Step 9: Generate assets
-safe_execute "Generating assets" "npx capacitor-assets generate --android" || exit 7
-
 # Step 10: Build APK/AAB if requested
 if [ "$BUILD_APK" = true ]; then
     if [ "$BUILD_TYPE" = "debug" ]; then
@@ -642,6 +648,9 @@ fi
 
 if [ "$BUILD_AAB" = true ]; then
     safe_execute "Building AAB" "cd android && ./gradlew bundleRelease && cd .." || exit 5
+    if [ "$BUILD_MODE" = "production" ]; then
+        safe_execute "Checking production AAB" "./scripts/check-prod-bundle.sh android/app/build/outputs/bundle/release/app-release.aab" || exit 10
+    fi
 fi
 
 # Step 11: Auto-run app if requested
diff --git a/scripts/build-ios.sh b/scripts/build-ios.sh
index 27867437..b432c124 100755
--- a/scripts/build-ios.sh
+++ b/scripts/build-ios.sh
@@ -680,6 +680,11 @@ safe_execute "Installing CocoaPods dependencies" "run_pod_install_with_workaroun
 # Step 6.6: Sync with Capacitor (uses run_cap_sync_with_workaround defined above for Xcode 26)
 safe_execute "Syncing with Capacitor" "run_cap_sync_with_workaround" || exit 6
 
+# Step 6.7: Verify the synced web bundle has production server defaults
+if [ "$BUILD_MODE" = "production" ]; then
+    safe_execute "Checking production bundle" "./scripts/check-prod-bundle.sh ios/App/App/public" || exit 10
+fi
+
 # Step 7: Generate assets
 safe_execute "Generating assets" "generate_ios_assets" || exit 7
 
diff --git a/scripts/check-prod-bundle.sh b/scripts/check-prod-bundle.sh
new file mode 100755
index 00000000..8d006bfb
--- /dev/null
+++ b/scripts/check-prod-bundle.sh
@@ -0,0 +1,100 @@
+#!/bin/bash
+# check-prod-bundle.sh
+# Fails if a built web bundle has test/dev server URLs baked in as defaults.
+#
+# Native packaging (gradlew bundleRelease, Xcode archive) ships whatever web
+# bundle was last synced into the native project, whether it came from a
+# --test, --dev, or --prod build. Run this on the bundle before uploading.
+#
+# Usage:
+#   ./scripts/check-prod-bundle.sh [PATH...]
+#
+# Each PATH is a directory (e.g. android/app/src/main/assets/public,
+# ios/App/App/public, an .xcarchive) or an .aab, .apk, or .ipa file.
+# With no PATH, checks the synced Android and iOS web assets plus the
+# release AAB if it exists.
+#
+# Detection: the canary URLs below appear in src/ only as AppString.TEST_*
+# enum values, which minify to `x.TEST_..._SERVER="<url>"`. Any other quoted
+# occurrence is a VITE_* default compiled in from .env.test or
+# .env.development (.env.development also uses the test image server).
+#
+# Exit codes: 0 = clean, 1 = test defaults found, 2 = bad input
+
+source "$(dirname "$0")/common.sh"
+
+CANARY_REGEX='"https://test(-image-api|-notify-api)?\.timesafari\.app"'
+ENUM_REGEX='TEST[0-9]*_[A-Z_]+="https'
+
+# Prints offending snippets from the JS files under a directory; returns 1 if any.
+check_js_dir() {
+    local dir="$1"
+    local js_count
+    js_count=$(find "$dir" -name "*.js" -path "*assets*" | wc -l | tr -d ' ')
+    if [ "$js_count" = "0" ]; then
+        log_error "No JS assets found under $dir"
+        return 2
+    fi
+
+    local hits
+    hits=$(find "$dir" -name "*.js" -path "*assets*" -print0 \
+        | xargs -0 grep -ohE ".{0,40}${CANARY_REGEX}" \
+        | grep -vE "$ENUM_REGEX")
+    if [ -n "$hits" ]; then
+        log_error "Test/dev server defaults found in bundle:"
+        echo "$hits" | sed 's/^/    /' >&2
+        return 1
+    fi
+    return 0
+}
+
+check_path() {
+    local path="$1"
+    local result
+
+    if [ -d "$path" ]; then
+        check_js_dir "$path"
+        result=$?
+    elif [ -f "$path" ]; then
+        case "$path" in
+            *.aab|*.apk|*.ipa) ;;
+            *)
+                log_error "Unsupported file type: $path"
+                return 2
+                ;;
+        esac
+        local tmp
+        tmp=$(mktemp -d)
+        unzip -q "$path" '*public/assets/*.js' -d "$tmp" 2>/dev/null
+        check_js_dir "$tmp"
+        result=$?
+        rm -rf "$tmp"
+    else
+        log_error "Not found: $path"
+        return 2
+    fi
+
+    if [ "$result" = "0" ]; then
+        log_success "Production defaults OK: $path"
+    else
+        log_error "Not a production bundle: $path"
+    fi
+    return $result
+}
+
+paths=("$@")
+if [ ${#paths[@]} -eq 0 ]; then
+    for p in android/app/src/main/assets/public \
+             ios/App/App/public \
+             android/app/build/outputs/bundle/release/app-release.aab; do
+        [ -e "$p" ] && paths+=("$p")
+    done
+fi
+
+status=0
+for p in "${paths[@]}"; do
+    check_path "$p"
+    rc=$?
+    [ $rc -gt $status ] && status=$rc
+done
+exit $status