Add findings and plan for Firebase Local Emulator Suite in local dev

.env.emulator

@@ -0,0 +1,18 @@
+NODE_ENV=development
+VUE_APP_ENV_NAME=develop
+
+VUE_APP_USE_FIREBASE_EMULATOR=true
+USE_FIREBASE_EMULATOR=true
+
+VUE_APP_FIREBASE_API_KEY=demo-api-key
+VUE_APP_FIREBASE_AUTH_DOMAIN=127.0.0.1
+VUE_APP_FIREBASE_DATABASE_URL=https://demo-shieldmaiden-default-rtdb.firebaseio.com
+VUE_APP_FIREBASE_PROJECT_ID=demo-shieldmaiden
+VUE_APP_FIREBASE_STORAGE_BUCKET=demo-shieldmaiden.appspot.com
+VUE_APP_FIREBASE_MESSAGING_SENDER_ID=000000000000
+
+FIREBASE_AUTH_EMULATOR_HOST=127.0.0.1:9099
+FIREBASE_DATABASE_EMULATOR_HOST=127.0.0.1:9000
+FIREBASE_STORAGE_EMULATOR_HOST=127.0.0.1:9199
+
+VUE_APP_HK_API_ROOT=https://api.harmlesskey.com

.gitignore

@@ -7,6 +7,7 @@ node_modules
 .env.local
 .env.*.local
 !.env.vault
+!.env.emulator
 
 # Log files
 npm-debug.log*
@@ -68,3 +69,8 @@ yarn-error.log*
 *.sln
 
 firebaseServiceAccountKey.json
+
+# Firebase emulator runtime artifacts
+*-debug.log
+.firebase/
+firebase-export-*/

emulator/database.rules.json

@@ -0,0 +1 @@
+{ "rules": { ".read": true, ".write": true } }

emulator/storage.rules

@@ -0,0 +1,8 @@
+rules_version = '2';
+service firebase.storage {
+	match /b/{bucket}/o {
+		match /{allPaths=**} {
+			allow read, write: if true;
+		}
+	}
+}

env.js

@@ -0,0 +1,15 @@
+/*
+ * Resolves which env file to load. Runs in a Node (non-transpiled) context.
+ * Selects .env.emulator when USE_FIREBASE_EMULATOR=true, or as a fallback when
+ * the per-environment .env.<NODE_ENV>.local file does not exist (sandbox / worktree case).
+ */
+const fs = require("fs");
+const path = require("path");
+
+module.exports = function resolveEnvFile(baseDir) {
+	const local = path.resolve(baseDir, `.env.${process.env.NODE_ENV}.local`);
+	if (process.env.USE_FIREBASE_EMULATOR === "true" || !fs.existsSync(local)) {
+		return path.resolve(baseDir, ".env.emulator");
+	}
+	return local;
+};

firebase.emulator.json

@@ -0,0 +1,11 @@
+{
+	"database": { "rules": "emulator/database.rules.json" },
+	"storage": { "rules": "emulator/storage.rules" },
+	"emulators": {
+		"auth":     { "port": 9099 },
+		"database": { "port": 9000 },
+		"storage":  { "port": 9199 },
+		"ui":       { "enabled": true, "port": 4000 },
+		"singleProjectMode": true
+	}
+}