Phase 3 testing fixes: Fastify 5, SSE→WebSocket+FCM, enums, security, session lifecycle

- Upgrade Fastify 4→5 with all plugins (@fastify/websocket 11, cors 11, sensible 6) - Migrate all SSE endpoints to WebSocket + FCM push (mitra chat requests, customer pairing status) - Add flutter_local_notifications for foreground push notifications with sound - Add splash screen to both apps (hide auth loading flash) - Introduce constants/enums across entire codebase (no raw string literals) - Move price tiers from hardcoded array to app_config DB (data-driven, includes 1-min test tier) - Add session ownership validation on all shared chat routes - Add ownership checks on endSession, respondToExtension, requestExtension - Fix session timer: auto-complete expired/stale sessions on server restart - Add 5-min grace period for abandoned closing sessions - Fix extension flow: proper session_resumed handling, clearExtensionRequest, closure grace timer cleanup - Fix chat screens: ConnectChat in initState, session status check on connect - Fix customer expired view: 5-min countdown, closure state priority over expired state - Fix mitra extension UI: loading spinner, disable buttons, handle EXTENSION_RESOLVED error - Fix GoRouter navigation consistency (no more Navigator.pushNamed) - Fix goodbye view keyboard overflow (SingleChildScrollView) - Add active session card on customer home screen with refresh on navigate back - Fix PricingBottomSheet extension mode (RequestExtension instead of new pairing) - Send session_resumed to both parties on extension accept Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-09 00:17:25 +08:00
parent b4efcf14c2
commit b0502ac92b
58 changed files with 2148 additions and 709 deletions
--- a/.claude/settings.local.json
+++ b/.claude/settings.local.json
@@ -1,9 +1,83 @@
 {
  "permissions": {
    "allow": [
-      "Bash(npm init:*)",
-      "Bash(cmd.exe /c \"npm --version\")",
-      "Bash(flutter --version)"
+      "Bash(git clone:*)",
+      "Bash(shopt -s dotglob)",
+      "Bash(cp -rn /tmp/halobestie-clone-temp/* /home/rama/workspaces/workspace-claude/halobestie-clone/)",
+      "Bash(rm -rf /tmp/halobestie-clone-temp)",
+      "Bash(git -C /home/rama/workspaces/workspace-claude/halobestie-clone log --oneline -5)",
+      "Read(//home/rama/workspaces/workspace-claude/backend/src/routes/internal/**)",
+      "Bash(git add:*)",
+      "Bash(git commit -m ':*)",
+      "Bash(git push:*)",
+      "Bash(flutter --version)",
+      "Bash(flutter devices:*)",
+      "Bash(flutter emulators:*)",
+      "Bash(flutter pub:*)",
+      "Bash(flutter run:*)",
+      "Bash(flutter create:*)",
+      "Bash(adb emu:*)",
+      "Bash(firebase --version)",
+      "Bash(flutterfire --version)",
+      "Bash(firebase projects:list)",
+      "Bash(npm install:*)",
+      "Bash(dart pub:*)",
+      "Bash(pkill -f \"flutter run\")",
+      "Bash(pkill -f \"gradle\")",
+      "Bash(kill 12672 12712 12809 14069 14567)",
+      "Bash(adb -s emulator-5554 emu kill)",
+      "Bash(timeout 5 bash -c 'echo > /dev/tcp/omv.sjamsani.id/5432 && echo \"PostgreSQL: reachable\" || echo \"PostgreSQL: unreachable\"')",
+      "Bash(timeout 5 bash -c 'echo > /dev/tcp/omv.sjamsani.id/6379 && echo \"Valkey: reachable\" || echo \"Valkey: unreachable\"')",
+      "Bash(PGPASSWORD=halobestie_clone psql -h omv.sjamsani.id -U halobestie_clone -d halobestie_clone -c \"SELECT 1 AS connected;\")",
+      "Bash(dpkg -l)",
+      "Bash(npm ls:*)",
+      "Bash(node -e ':*)",
+      "Bash(npm run:*)",
+      "Bash(timeout 5 bash -c 'echo > /dev/tcp/192.168.88.247/3000 && echo \"Backend reachable via static IP\" || echo \"Not reachable\"')",
+      "Bash(pkill -f \"flutter_tools.snapshot run\")",
+      "Bash(curl -s http://192.168.88.247:3000/)",
+      "Bash(lscpu)",
+      "Bash(pkill -f \"flutter_tools.snapshot run.*chrome\")",
+      "Bash(curl -s -X OPTIONS -H \"Origin: http://localhost\" -H \"Access-Control-Request-Method: POST\" -H \"Access-Control-Request-Headers: authorization,content-type\" -I http://192.168.88.247:3000/api/mitra/auth/verify)",
+      "Bash(node -e \"import\\('@fastify/cors'\\).then\\(m => console.log\\('cors loaded ok'\\)\\)\")",
+      "Bash(curl -sv -X OPTIONS -H \"Origin: http://localhost\" -H \"Access-Control-Request-Method: POST\" http://192.168.88.247:3000/api/mitra/auth/verify)",
+      "Bash(pkill -f \"node.*server.js\")",
+      "Bash(curl -sv -X OPTIONS -H \"Origin: http://localhost\" -H \"Access-Control-Request-Method: POST\" -H \"Access-Control-Request-Headers: authorization,content-type\" http://192.168.88.247:3000/api/mitra/auth/verify)",
+      "Bash(pkill -f \"flutter_tools.snapshot run.*emulator\")",
+      "Bash(curl -s http://192.168.88.247:3000/api/shared/config/anonymity)",
+      "Bash(flutter build:*)",
+      "Bash(keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android)",
+      "Read(//home/rama/.android/avd/**)",
+      "Bash(node -e \"const pkg = require\\('./node_modules/@fastify/websocket/package.json'\\); console.log\\('@fastify/websocket:', pkg.version\\); const fp = require\\('./node_modules/fastify/package.json'\\); console.log\\('fastify:', fp.version\\)\")",
+      "Bash(node -e \"const p=require\\('fs'\\).readFileSync\\('/dev/stdin','utf8'\\); const j=JSON.parse\\(p\\); console.log\\(JSON.stringify\\(j.dependencies, null, 2\\)\\)\")",
+      "Bash(node -e \"const p=require\\('fs'\\).readFileSync\\('/dev/stdin','utf8'\\); const j=JSON.parse\\(p\\); console.log\\(JSON.stringify\\(j.scripts, null, 2\\)\\)\")",
+      "WebSearch",
+      "WebFetch(domain:fastify.dev)",
+      "Bash(grep -E \"\\\\.js$\")",
+      "Bash(node -e \"const f=require\\('fastify/package.json'\\); const w=require\\('@fastify/websocket/package.json'\\); const c=require\\('@fastify/cors/package.json'\\); const s=require\\('@fastify/sensible/package.json'\\); console.log\\('fastify:', f.version, '| websocket:', w.version, '| cors:', c.version, '| sensible:', s.version\\)\")",
+      "Bash(pkill -f \"flutter run.*emulator-5556\")",
+      "Bash(pkill -f \"qemu-system\")",
+      "Bash(kill -9 7413 17891)",
+      "Bash(kill -9 5752 5841)",
+      "Bash(sed -i 's/hw.cpu.ncore=12/hw.cpu.ncore=4/' ~/.android/avd/Medium_Phone.avd/config.ini)",
+      "Bash(sed -i 's/hw.cpu.ncore = 6/hw.cpu.ncore = 4/' ~/.android/avd/Medium_Phone.avd/hardware-qemu.ini)",
+      "Bash(xargs kill:*)",
+      "Bash(pkill -f \"Mitra_Phone\")",
+      "Bash(kill -9 22483 21705)",
+      "Bash(kill -9 46545)",
+      "Bash(node -e \"import admin from 'firebase-admin'; import {initFirebase} from './src/plugins/firebase.js'; initFirebase\\(\\); const t = await admin.auth\\(\\).createCustomToken\\('fUVSXRF3k1S97aqSCPH5S6ZYXZT2'\\); console.log\\(t\\)\")",
+      "Bash(curl -s http://192.168.88.247:3000/api/client/chat/pricing -H \"Authorization: Bearer $\\(node -e \"import admin from 'firebase-admin'; import {initFirebase} from './src/plugins/firebase.js'; initFirebase\\(\\); const t = await admin.auth\\(\\).createCustomToken\\('fUVSXRF3k1S97aqSCPH5S6ZYXZT2'\\); console.log\\(t\\)\" 2>/dev/null\\)\")",
+      "Bash(dart analyze:*)",
+      "Read(//home/rama/workspaces/workspace-claude/**)",
+      "Bash(pkill -f \"flutter run.*52002\")",
+      "Bash(pkill -f \"flutter run.*emulator-5554\")",
+      "Bash(fuser -k 3000/tcp)",
+      "Bash(fuser -k 3001/tcp)",
+      "Bash(fuser 3000/tcp)",
+      "Bash(kill -9 923894)"
+    ],
+    "additionalDirectories": [
+      "/home/rama/workspaces/workspace-claude/halobestie-clone/backend/src"
    ]
  }
 }
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -8,11 +8,11 @@
      "name": "halo-bestie-backend",
      "version": "1.0.0",
      "dependencies": {
-        "@fastify/cors": "^9.0.1",
-        "@fastify/sensible": "^5.6.0",
-        "@fastify/websocket": "^11.2.0",
+        "@fastify/cors": "^11.0.0",
+        "@fastify/sensible": "^6.0.0",
+        "@fastify/websocket": "^11.0.0",
        "dotenv": "^16.4.5",
-        "fastify": "^4.28.1",
+        "fastify": "^5.0.0",
        "firebase-admin": "^12.2.0",
        "ioredis": "^5.4.1",
        "pg": "^8.12.0",
@@ -24,14 +24,24 @@
      }
    },
    "node_modules/@fastify/ajv-compiler": {
-      "version": "3.6.0",
-      "resolved": "https://registry.npmjs.org/@fastify/ajv-compiler/-/ajv-compiler-3.6.0.tgz",
-      "integrity": "sha512-LwdXQJjmMD+GwLOkP7TVC68qa+pSSogeWWmznRJ/coyTcfe9qA05AHFSe1eZFwK6q+xVRpChnvFUkf1iYaSZsQ==",
+      "version": "4.0.5",
+      "resolved": "https://registry.npmjs.org/@fastify/ajv-compiler/-/ajv-compiler-4.0.5.tgz",
+      "integrity": "sha512-KoWKW+MhvfTRWL4qrhUwAAZoaChluo0m0vbiJlGMt2GXvL4LVPQEjt8kSpHI3IBq5Rez8fg+XeH3cneztq+C7A==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "ajv": "^8.11.0",
-        "ajv-formats": "^2.1.1",
-        "fast-uri": "^2.0.0"
+        "ajv": "^8.12.0",
+        "ajv-formats": "^3.0.1",
+        "fast-uri": "^3.0.0"
      }
    },
    "node_modules/@fastify/busboy": {
@@ -41,51 +51,137 @@
      "license": "MIT"
    },
    "node_modules/@fastify/cors": {
-      "version": "9.0.1",
-      "resolved": "https://registry.npmjs.org/@fastify/cors/-/cors-9.0.1.tgz",
-      "integrity": "sha512-YY9Ho3ovI+QHIL2hW+9X4XqQjXLjJqsU+sMV/xFsxZkE8p3GNnYVFpoOxF7SsP5ZL76gwvbo3V9L+FIekBGU4Q==",
+      "version": "11.2.0",
+      "resolved": "https://registry.npmjs.org/@fastify/cors/-/cors-11.2.0.tgz",
+      "integrity": "sha512-LbLHBuSAdGdSFZYTLVA3+Ch2t+sA6nq3Ejc6XLAKiQ6ViS2qFnvicpj0htsx03FyYeLs04HfRNBsz/a8SvbcUw==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "fastify-plugin": "^4.0.0",
-        "mnemonist": "0.39.6"
+        "fastify-plugin": "^5.0.0",
+        "toad-cache": "^3.7.0"
      }
    },
    "node_modules/@fastify/error": {
-      "version": "3.4.1",
-      "resolved": "https://registry.npmjs.org/@fastify/error/-/error-3.4.1.tgz",
-      "integrity": "sha512-wWSvph+29GR783IhmvdwWnN4bUxTD01Vm5Xad4i7i1VuAOItLvbPAb69sb0IQ2N57yprvhNIwAP5B6xfKTmjmQ==",
+      "version": "4.2.0",
+      "resolved": "https://registry.npmjs.org/@fastify/error/-/error-4.2.0.tgz",
+      "integrity": "sha512-RSo3sVDXfHskiBZKBPRgnQTtIqpi/7zhJOEmAxCiBcM7d0uwdGdxLlsCaLzGs8v8NnxIRlfG0N51p5yFaOentQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT"
    },
    "node_modules/@fastify/fast-json-stringify-compiler": {
-      "version": "4.3.0",
-      "resolved": "https://registry.npmjs.org/@fastify/fast-json-stringify-compiler/-/fast-json-stringify-compiler-4.3.0.tgz",
-      "integrity": "sha512-aZAXGYo6m22Fk1zZzEUKBvut/CIIQe/BapEORnxiD5Qr0kPHqqI69NtEMCme74h+at72sPhbkb4ZrLd1W3KRLA==",
+      "version": "5.0.3",
+      "resolved": "https://registry.npmjs.org/@fastify/fast-json-stringify-compiler/-/fast-json-stringify-compiler-5.0.3.tgz",
+      "integrity": "sha512-uik7yYHkLr6fxd8hJSZ8c+xF4WafPK+XzneQDPU+D10r5X19GW8lJcom2YijX2+qtFF1ENJlHXKFM9ouXNJYgQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "fast-json-stringify": "^5.7.0"
+        "fast-json-stringify": "^6.0.0"
      }
    },
+    "node_modules/@fastify/forwarded": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/@fastify/forwarded/-/forwarded-3.0.1.tgz",
+      "integrity": "sha512-JqDochHFqXs3C3Ml3gOY58zM7OqO9ENqPo0UqAjAjH8L01fRZqwX9iLeX34//kiJubF7r2ZQHtBRU36vONbLlw==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "MIT"
+    },
    "node_modules/@fastify/merge-json-schemas": {
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-      "resolved": "https://registry.npmjs.org/@fastify/merge-json-schemas/-/merge-json-schemas-0.1.1.tgz",
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+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/@fastify/merge-json-schemas/-/merge-json-schemas-0.2.1.tgz",
+      "integrity": "sha512-OA3KGBCy6KtIvLf8DINC5880o5iBlDX4SxzLQS8HorJAbqluzLRn80UXU0bxZn7UOFhFgpRJDasfwn9nG4FG4A==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "fast-deep-equal": "^3.1.3"
+        "dequal": "^2.0.3"
+      }
+    },
+    "node_modules/@fastify/proxy-addr": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/@fastify/proxy-addr/-/proxy-addr-5.1.0.tgz",
+      "integrity": "sha512-INS+6gh91cLUjB+PVHfu1UqcB76Sqtpyp7bnL+FYojhjygvOPA9ctiD/JDKsyD9Xgu4hUhCSJBPig/w7duNajw==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@fastify/forwarded": "^3.0.0",
+        "ipaddr.js": "^2.1.0"
      }
    },
    "node_modules/@fastify/sensible": {
-      "version": "5.6.0",
-      "resolved": "https://registry.npmjs.org/@fastify/sensible/-/sensible-5.6.0.tgz",
-      "integrity": "sha512-Vq6Z2ZQy10GDqON+hvLF52K99s9et5gVVxTul5n3SIAf0Kq5QjPRUKkAMT3zPAiiGvoHtS3APa/3uaxfDgCODQ==",
+      "version": "6.0.4",
+      "resolved": "https://registry.npmjs.org/@fastify/sensible/-/sensible-6.0.4.tgz",
+      "integrity": "sha512-1vxcCUlPMew6WroK8fq+LVOwbsLtX+lmuRuqpcp6eYqu6vmkLwbKTdBWAZwbeaSgCfW4tzUpTIHLLvTiQQ1BwQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "@lukeed/ms": "^2.0.1",
-        "fast-deep-equal": "^3.1.1",
-        "fastify-plugin": "^4.0.0",
+        "@lukeed/ms": "^2.0.2",
+        "dequal": "^2.0.3",
+        "fastify-plugin": "^5.0.0",
        "forwarded": "^0.2.0",
        "http-errors": "^2.0.0",
-        "type-is": "^1.6.18",
+        "type-is": "^2.0.1",
        "vary": "^1.1.2"
      }
    },
@@ -110,22 +206,6 @@
        "ws": "^8.16.0"
      }
    },
-    "node_modules/@fastify/websocket/node_modules/fastify-plugin": {
-      "version": "5.1.0",
-      "resolved": "https://registry.npmjs.org/fastify-plugin/-/fastify-plugin-5.1.0.tgz",
-      "integrity": "sha512-FAIDA8eovSt5qcDgcBvDuX/v0Cjz0ohGhENZ/wpc3y+oZCY2afZ9Baqql3g/lC+OHRnciQol4ww7tuthOb9idw==",
-      "funding": [
-        {
-          "type": "github",
-          "url": "https://github.com/sponsors/fastify"
-        },
-        {
-          "type": "opencollective",
-          "url": "https://opencollective.com/fastify"
-        }
-      ],
-      "license": "MIT"
-    },
    "node_modules/@firebase/app-check-interop-types": {
      "version": "0.3.2",
      "resolved": "https://registry.npmjs.org/@firebase/app-check-interop-types/-/app-check-interop-types-0.3.2.tgz",
@@ -594,9 +674,9 @@
      }
    },
    "node_modules/ajv-formats": {
-      "version": "2.1.1",
-      "resolved": "https://registry.npmjs.org/ajv-formats/-/ajv-formats-2.1.1.tgz",
-      "integrity": "sha512-Wx0Kx52hxE7C18hkMEggYlEifqWZtYaRgouJor+WMdPnQyEK13vgEWyVNup7SoeeoLMsr4kf5h6dOW11I15MUA==",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/ajv-formats/-/ajv-formats-3.0.1.tgz",
+      "integrity": "sha512-8iUql50EUR+uUcdRQ3HDqa6EVyo3docL8g5WJ3FNcWmu62IbkGUue/pEyLBW8VGKKucTPgqeks4fIU1DA4yowQ==",
      "license": "MIT",
      "dependencies": {
        "ajv": "^8.0.0"
@@ -610,22 +690,6 @@
        }
      }
    },
-    "node_modules/ajv/node_modules/fast-uri": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/fast-uri/-/fast-uri-3.1.0.tgz",
-      "integrity": "sha512-iPeeDKJSWf4IEOasVVrknXpaBV0IApz/gp7S2bb7Z4Lljbl2MGJRqInZiUrQwV16cpzw/D3S5j5Julj/gT52AA==",
-      "funding": [
-        {
-          "type": "github",
-          "url": "https://github.com/sponsors/fastify"
-        },
-        {
-          "type": "opencollective",
-          "url": "https://opencollective.com/fastify"
-        }
-      ],
-      "license": "BSD-3-Clause"
-    },
    "node_modules/ansi-regex": {
      "version": "5.0.1",
      "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-5.0.1.tgz",
@@ -689,12 +753,22 @@
      }
    },
    "node_modules/avvio": {
-      "version": "8.4.0",
-      "resolved": "https://registry.npmjs.org/avvio/-/avvio-8.4.0.tgz",
-      "integrity": "sha512-CDSwaxINFy59iNwhYnkvALBwZiTydGkOecZyPkqBpABYR1KqGEsET0VOOYDwtleZSUIdeY36DC2bSZ24CO1igA==",
+      "version": "9.2.0",
+      "resolved": "https://registry.npmjs.org/avvio/-/avvio-9.2.0.tgz",
+      "integrity": "sha512-2t/sy01ArdHHE0vRH5Hsay+RtCZt3dLPji7W7/MMOCEgze5b7SNDC4j5H6FnVgPkI1MTNFGzHdHrVXDDl7QSSQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "@fastify/error": "^3.3.0",
+        "@fastify/error": "^4.0.0",
        "fastq": "^1.17.1"
      }
    },
@@ -806,15 +880,28 @@
        "node": ">= 0.8"
      }
    },
-    "node_modules/cookie": {
-      "version": "0.7.2",
-      "resolved": "https://registry.npmjs.org/cookie/-/cookie-0.7.2.tgz",
-      "integrity": "sha512-yki5XnKuf750l50uGTllt6kKILY4nQ1eNIQatoXEByZ5dWgnKqbnqmTrBE5B4N7lrMJKQ2ytWMiTO2o0v6Ew/w==",
+    "node_modules/content-type": {
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+      "version": "0.5.0",
+      "resolved": "https://registry.npmjs.org/ret/-/ret-0.5.0.tgz",
+      "integrity": "sha512-I1XxrZSQ+oErkRR4jYbAyEEu2I0avBvvMM5JN+6EBprOGRCs63ENqZ3vjavq8fBw2+62G5LF5XelKwuJpcvcxw==",
      "license": "MIT",
      "engines": {
        "node": ">=10"
@@ -2407,12 +2512,25 @@
      "license": "MIT"
    },
    "node_modules/safe-regex2": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/safe-regex2/-/safe-regex2-3.1.0.tgz",
-      "integrity": "sha512-RAAZAGbap2kBfbVhvmnTFv73NWLMvDGOITFYTZBAaY8eR+Ir4ef7Up/e7amo+y1+AH+3PtLkrt9mvcTsG9LXug==",
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/safe-regex2/-/safe-regex2-5.1.0.tgz",
+      "integrity": "sha512-pNHAuBW7TrcleFHsxBr5QMi/Iyp0ENjUKz7GCcX1UO7cMh+NmVK6HxQckNL1tJp1XAJVjG6B8OKIPqodqj9rtw==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "MIT",
      "dependencies": {
-        "ret": "~0.4.0"
+        "ret": "~0.5.0"
+      },
+      "bin": {
+        "safe-regex2": "bin/safe-regex2.js"
      }
    },
    "node_modules/safe-stable-stringify": {
@@ -2425,9 +2543,19 @@
      }
    },
    "node_modules/secure-json-parse": {
-      "version": "2.7.0",
-      "resolved": "https://registry.npmjs.org/secure-json-parse/-/secure-json-parse-2.7.0.tgz",
-      "integrity": "sha512-6aU+Rwsezw7VR8/nyvKTx8QpWH9FrcYiXXlqC4z5d5XQBDRqtbfsRjnwGyqbi3gddNtWHuEk9OANUotL26qKUw==",
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/secure-json-parse/-/secure-json-parse-4.1.0.tgz",
+      "integrity": "sha512-l4KnYfEyqYJxDwlNVyRfO2E4NTHfMKAWdUuA8J0yve2Dz/E/PdBepY03RvyJpssIpRFwJoCD55wA+mEDs6ByWA==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
      "license": "BSD-3-Clause"
    },
    "node_modules/semver": {
@@ -2659,18 +2787,44 @@
      "license": "0BSD"
    },
    "node_modules/type-is": {
-      "version": "1.6.18",
-      "resolved": "https://registry.npmjs.org/type-is/-/type-is-1.6.18.tgz",
-      "integrity": "sha512-TkRKr9sUTxEH8MdfuCSP7VizJyzRNMjj2J2do2Jr3Kym598JVdEksuzPQCnlFPW4ky9Q+iA+ma9BGm06XQBy8g==",
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/type-is/-/type-is-2.0.1.tgz",
+      "integrity": "sha512-OZs6gsjF4vMp32qrCbiVSkrFmXtG/AZhY3t0iAMrMBiAZyV9oALtXO8hsrHbMXF9x6L3grlFuwW2oAz7cav+Gw==",
      "license": "MIT",
      "dependencies": {
-        "media-typer": "0.3.0",
-        "mime-types": "~2.1.24"
+        "content-type": "^1.0.5",
+        "media-typer": "^1.1.0",
+        "mime-types": "^3.0.0"
      },
      "engines": {
        "node": ">= 0.6"
      }
    },
+    "node_modules/type-is/node_modules/mime-db": {
+      "version": "1.54.0",
+      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.54.0.tgz",
+      "integrity": "sha512-aU5EJuIN2WDemCcAp2vFBfp/m4EAhWJnUNSSw0ixs7/kXbd6Pg64EmwJkNdFhB8aWt1sH2CTXrLxo/iAGV3oPQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 0.6"
+      }
+    },
+    "node_modules/type-is/node_modules/mime-types": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-3.0.2.tgz",
+      "integrity": "sha512-Lbgzdk0h4juoQ9fCKXW4by0UJqj+nOOrI9MJ1sSj4nI8aI2eo1qmvQEie4VD1glsS250n15LsWsYtCugiStS5A==",
+      "license": "MIT",
+      "dependencies": {
+        "mime-db": "^1.54.0"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/express"
+      }
+    },
    "node_modules/undici-types": {
      "version": "7.18.2",
      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.18.2.tgz",
--- a/backend/package.json
+++ b/backend/package.json
@@ -11,11 +11,11 @@
    "db:seed": "node src/db/seed.js"
  },
  "dependencies": {
-    "@fastify/cors": "^9.0.1",
-    "@fastify/sensible": "^5.6.0",
-    "@fastify/websocket": "^11.2.0",
+    "@fastify/cors": "^11.0.0",
+    "@fastify/sensible": "^6.0.0",
+    "@fastify/websocket": "^11.0.0",
    "dotenv": "^16.4.5",
-    "fastify": "^4.28.1",
+    "fastify": "^5.0.0",
    "firebase-admin": "^12.2.0",
    "ioredis": "^5.4.1",
    "pg": "^8.12.0",
--- a/backend/src/constants.js
+++ b/backend/src/constants.js
@@ -0,0 +1,101 @@
+// User types
+export const UserType = Object.freeze({
+  CUSTOMER: 'customer',
+  MITRA: 'mitra',
+})
+
+// Chat session statuses
+export const SessionStatus = Object.freeze({
+  SEARCHING: 'searching',
+  PENDING_ACCEPTANCE: 'pending_acceptance',
+  PENDING_PAYMENT: 'pending_payment',
+  ACTIVE: 'active',
+  EXTENDING: 'extending',
+  CLOSING: 'closing',
+  COMPLETED: 'completed',
+  CANCELLED: 'cancelled',
+  EXPIRED: 'expired',
+})
+
+// Chat message statuses
+export const MessageStatus = Object.freeze({
+  SENT: 'sent',
+  DELIVERED: 'delivered',
+  READ: 'read',
+})
+
+// Chat message types
+export const MessageType = Object.freeze({
+  TEXT: 'text',
+})
+
+// Chat request notification responses
+export const NotificationResponse = Object.freeze({
+  ACCEPTED: 'accepted',
+  DECLINED: 'declined',
+  IGNORED: 'ignored',
+})
+
+// Session extension statuses
+export const ExtensionStatus = Object.freeze({
+  PENDING: 'pending',
+  ACCEPTED: 'accepted',
+  REJECTED: 'rejected',
+  TIMEOUT: 'timeout',
+})
+
+// Customer transaction types
+export const TransactionType = Object.freeze({
+  FREE_TRIAL: 'free_trial',
+  PAID: 'paid',
+  EXTENSION: 'extension',
+})
+
+// Who ended a session
+export const EndedBy = Object.freeze({
+  SYSTEM: 'system',
+  CUSTOMER: 'customer',
+  MITRA: 'mitra',
+})
+
+// WebSocket message types
+export const WsMessage = Object.freeze({
+  // Auth
+  AUTH: 'auth',
+  AUTH_OK: 'auth_ok',
+  ERROR: 'error',
+
+  // Chat
+  MESSAGE: 'message',
+  MESSAGE_ACK: 'message_ack',
+  MESSAGE_STATUS: 'message_status',
+  TYPING: 'typing',
+
+  // Pairing
+  CHAT_REQUEST: 'chat_request',
+  CHAT_REQUEST_CLOSED: 'chat_request_closed',
+  PAIRED: 'paired',
+
+  // Session lifecycle
+  SESSION_TIMER: 'session_timer',
+  SESSION_EXPIRED: 'session_expired',
+  SESSION_CLOSING: 'session_closing',
+  SESSION_COMPLETED: 'session_completed',
+  SESSION_ENDED: 'session_ended',
+  SESSION_PAUSED: 'session_paused',
+  SESSION_RESUMED: 'session_resumed',
+  SESSION_ASSIGNED: 'session_assigned',
+  SESSION_REROUTED: 'session_rerouted',
+  REROUTED: 'rerouted',
+
+  // Extension
+  EXTENSION_REQUEST: 'extension_request',
+  EXTENSION_RESPONSE: 'extension_response',
+
+  // Early end
+  EARLY_END: 'early_end',
+
+  // Delivery
+  DELIVERED: 'delivered',
+  READ: 'read',
+})
--- a/backend/src/db/migrate.js
+++ b/backend/src/db/migrate.js
@@ -261,6 +261,19 @@ const migrate = async () => {
    ON CONFLICT (key) DO NOTHING
  `

+  await sql`
+    INSERT INTO app_config (key, value)
+    VALUES ('price_tiers', ${sql.json({ tiers: [
+      { duration_minutes: 1, price: 5000, label: '1 Menit (Test)' },
+      { duration_minutes: 15, price: 30000, label: '15 Menit' },
+      { duration_minutes: 30, price: 60000, label: '30 Menit' },
+      { duration_minutes: 45, price: 100000, label: '45 Menit' },
+      { duration_minutes: 60, price: 150000, label: '60 Menit' },
+      { duration_minutes: 1440, price: 250000, label: '24 Jam' },
+    ]})})
+    ON CONFLICT (key) DO NOTHING
+  `
+
  console.log('Migration complete.')
  await sql.end()
 }
--- a/backend/src/plugins/websocket.js
+++ b/backend/src/plugins/websocket.js
@@ -3,6 +3,7 @@ import { verifyFirebaseToken } from './firebase.js'
 import { getCustomerByFirebaseUid } from '../services/customer.service.js'
 import { getMitraByFirebaseUid } from '../services/mitra.service.js'
 import { subscribe, publish } from './valkey.js'
+import { UserType, WsMessage } from '../constants.js'

 // Track active WebSocket connections: sessionId → { customer, mitra }
 const sessionConnections = new Map()
@@ -56,24 +57,24 @@ export const registerWebSocketRoute = (app) => {
      try {
        msg = JSON.parse(raw.toString())
      } catch {
-        send({ type: 'error', message: 'Invalid JSON' })
+        send({ type: WsMessage.ERROR, message: 'Invalid JSON' })
        return
      }

      // Handle auth message
-      if (msg.type === 'auth') {
+      if (msg.type === WsMessage.AUTH) {
        try {
          const decoded = await verifyFirebaseToken(msg.token)
          const customer = await getCustomerByFirebaseUid(decoded.uid)
          const mitra = customer ? null : await getMitraByFirebaseUid(decoded.uid)

          if (!customer && !mitra) {
-            send({ type: 'error', message: 'Account not found' })
+            send({ type: WsMessage.ERROR, message: 'Account not found' })
            socket.close()
            return
          }

-          const userType = customer ? 'customer' : 'mitra'
+          const userType = customer ? UserType.CUSTOMER : UserType.MITRA
          const userId = customer ? customer.id : mitra.id
          const sessionId = msg.session_id

@@ -101,9 +102,9 @@ export const registerWebSocketRoute = (app) => {
            valkeyUnsubscribes.push(unsub)
          }

-          send({ type: 'auth_ok', user_type: userType, user_id: userId })
+          send({ type: WsMessage.AUTH_OK, user_type: userType, user_id: userId })
        } catch (err) {
-          send({ type: 'error', message: 'Authentication failed' })
+          send({ type: WsMessage.ERROR, message: 'Authentication failed' })
          socket.close()
        }
        return
@@ -111,7 +112,7 @@ export const registerWebSocketRoute = (app) => {

      // All other messages require authentication
      if (!authenticatedUser) {
-        send({ type: 'error', message: 'Not authenticated. Send auth message first.' })
+        send({ type: WsMessage.ERROR, message: 'Not authenticated. Send auth message first.' })
        return
      }

@@ -135,7 +136,7 @@ export const registerWebSocketRoute = (app) => {
          const conns = sessionConnections.get(authenticatedUser.sessionId)
          if (conns) {
            delete conns[authenticatedUser.type]
-            if (!conns.customer && !conns.mitra) {
+            if (!conns[UserType.CUSTOMER] && !conns[UserType.MITRA]) {
              sessionConnections.delete(authenticatedUser.sessionId)
            }
          }
--- a/backend/src/routes/internal/config.routes.js
+++ b/backend/src/routes/internal/config.routes.js
@@ -101,4 +101,31 @@ export const internalConfigRoutes = async (app) => {
    const config = await setEarlyEndConfig({ mitra_enabled, customer_enabled })
    return reply.send({ success: true, data: config })
  })
+
+  // --- Price Tiers ---
+  app.get('/price-tiers', {
+    preHandler: [authenticate, attachCcUser, requirePermission('config', 'read')],
+  }, async (request, reply) => {
+    const { getPriceTiers } = await import('../../services/pricing.service.js')
+    const tiers = await getPriceTiers()
+    return reply.send({ success: true, data: tiers })
+  })
+
+  app.patch('/price-tiers', {
+    preHandler: [authenticate, attachCcUser, requirePermission('config', 'update')],
+  }, async (request, reply) => {
+    const { tiers } = request.body ?? {}
+    if (!Array.isArray(tiers) || tiers.length === 0) {
+      return reply.code(422).send({ success: false, error: { code: 'VALIDATION_ERROR', message: 'tiers must be a non-empty array' } })
+    }
+    for (const t of tiers) {
+      if (!t.duration_minutes || t.price === undefined || !t.label) {
+        return reply.code(422).send({ success: false, error: { code: 'VALIDATION_ERROR', message: 'Each tier needs duration_minutes, price, and label' } })
+      }
+    }
+    const { getDb } = await import('../../db/client.js')
+    const sql = getDb()
+    await sql`UPDATE app_config SET value = ${sql.json({ tiers })}, updated_at = NOW() WHERE key = 'price_tiers'`
+    return reply.send({ success: true, data: tiers })
+  })
 }
--- a/backend/src/routes/public/client.chat.routes.js
+++ b/backend/src/routes/public/client.chat.routes.js
@@ -1,10 +1,10 @@
 import { authenticate } from '../../plugins/auth.js'
 import { getCustomerByFirebaseUid } from '../../services/customer.service.js'
-import { createPairingRequest, cancelPairingRequest, getSessionStatus } from '../../services/pairing.service.js'
+import { createPairingRequest, cancelPairingRequest } from '../../services/pairing.service.js'
 import { getActiveSessionByCustomer, endSession, getCustomerHistory } from '../../services/session.service.js'
-import { subscribe } from '../../plugins/valkey.js'
 import { getPricingForCustomer, isValidTier, isCustomerEligibleForFreeTrial, getFreeTrial } from '../../services/pricing.service.js'
 import { requestExtension } from '../../services/extension.service.js'
+import { EndedBy } from '../../constants.js'

 const resolveCustomer = async (request, reply) => {
  const customer = await getCustomerByFirebaseUid(request.firebaseUser.uid)
@@ -52,7 +52,7 @@ export const clientChatRoutes = async (app) => {
      })
    }

-    if (!isValidTier(duration_minutes, price)) {
+    if (!(await isValidTier(duration_minutes, price))) {
      return reply.code(400).send({
        success: false,
        error: { code: 'INVALID_TIER', message: 'Invalid price tier selection' },
@@ -63,43 +63,6 @@ export const clientChatRoutes = async (app) => {
    return reply.code(201).send({ success: true, data: session })
  })

-  app.get('/request/:sessionId/status', { preHandler: [authenticate, resolveCustomer] }, async (request, reply) => {
-    const { sessionId } = request.params
-
-    // SSE stream for real-time status updates
-    reply.raw.writeHead(200, {
-      'Content-Type': 'text/event-stream',
-      'Cache-Control': 'no-cache',
-      'Connection': 'keep-alive',
-    })
-
-    // Send current status immediately
-    const current = await getSessionStatus(sessionId)
-    if (current) {
-      reply.raw.write(`data: ${JSON.stringify(current)}\n\n`)
-    }
-
-    // If already in a terminal state, close
-    if (current && ['active', 'completed', 'cancelled', 'expired'].includes(current.status)) {
-      reply.raw.end()
-      return
-    }
-
-    // Subscribe to status updates
-    const unsubscribe = subscribe(`session:${sessionId}:status`, (data) => {
-      reply.raw.write(`data: ${JSON.stringify(data)}\n\n`)
-      if (['paired', 'expired', 'session_ended'].includes(data.type)) {
-        reply.raw.end()
-        unsubscribe()
-      }
-    })
-
-    // Clean up on client disconnect
-    request.raw.on('close', () => {
-      unsubscribe()
-    })
-  })
-
  app.post('/request/:sessionId/cancel', { preHandler: [authenticate, resolveCustomer] }, async (request, reply) => {
    const session = await cancelPairingRequest(request.params.sessionId, request.customer.id)
    return reply.send({ success: true, data: session })
@@ -111,7 +74,7 @@ export const clientChatRoutes = async (app) => {
  })

  app.post('/session/:sessionId/end', { preHandler: [authenticate, resolveCustomer] }, async (request, reply) => {
-    const session = await endSession(request.params.sessionId, 'customer')
+    const session = await endSession(request.params.sessionId, EndedBy.CUSTOMER, request.customer.id)
    return reply.send({ success: true, data: session })
  })

--- a/backend/src/routes/public/mitra.chat.routes.js
+++ b/backend/src/routes/public/mitra.chat.routes.js
@@ -2,8 +2,8 @@ import { authenticate } from '../../plugins/auth.js'
 import { getMitraByFirebaseUid } from '../../services/mitra.service.js'
 import { acceptPairingRequest, declinePairingRequest } from '../../services/pairing.service.js'
 import { getActiveSessionsByMitra, endSession, getMitraHistory } from '../../services/session.service.js'
-import { subscribe } from '../../plugins/valkey.js'
 import { respondToExtension } from '../../services/extension.service.js'
+import { EndedBy } from '../../constants.js'

 const resolveMitra = async (request, reply) => {
  const mitra = await getMitraByFirebaseUid(request.firebaseUser.uid)
@@ -23,31 +23,6 @@ const resolveMitra = async (request, reply) => {
 }

 export const mitraChatRoutes = async (app) => {
-  app.get('/incoming', { preHandler: [authenticate, resolveMitra] }, async (request, reply) => {
-    const mitraId = request.mitra.id
-
-    // SSE stream for incoming chat requests
-    reply.raw.writeHead(200, {
-      'Content-Type': 'text/event-stream',
-      'Cache-Control': 'no-cache',
-      'Connection': 'keep-alive',
-    })
-
-    // Keep-alive ping
-    const pingInterval = setInterval(() => {
-      reply.raw.write(': ping\n\n')
-    }, 15_000)
-
-    const unsubscribe = subscribe(`mitra:${mitraId}:requests`, (data) => {
-      reply.raw.write(`data: ${JSON.stringify(data)}\n\n`)
-    })
-
-    request.raw.on('close', () => {
-      clearInterval(pingInterval)
-      unsubscribe()
-    })
-  })
-
  app.post('/:sessionId/accept', { preHandler: [authenticate, resolveMitra] }, async (request, reply) => {
    const session = await acceptPairingRequest(request.params.sessionId, request.mitra.id)
    return reply.send({ success: true, data: session })
@@ -64,7 +39,7 @@ export const mitraChatRoutes = async (app) => {
  })

  app.post('/sessions/:sessionId/end', { preHandler: [authenticate, resolveMitra] }, async (request, reply) => {
-    const session = await endSession(request.params.sessionId, 'mitra')
+    const session = await endSession(request.params.sessionId, EndedBy.MITRA, request.mitra.id)
    return reply.send({ success: true, data: session })
  })

--- a/backend/src/routes/public/shared.chat.routes.js
+++ b/backend/src/routes/public/shared.chat.routes.js
@@ -4,17 +4,21 @@ import { getMitraByFirebaseUid } from '../../services/mitra.service.js'
 import { getMessages } from '../../services/chat.service.js'
 import { getSessionClosures } from '../../services/closure.service.js'
 import { registerDeviceToken } from '../../services/notification.service.js'
+import { getDb } from '../../db/client.js'
+import { UserType } from '../../constants.js'
+
+const sql = getDb()

 const resolveUser = async (request, reply) => {
  const customer = await getCustomerByFirebaseUid(request.firebaseUser.uid)
  if (customer) {
-    request.userType = 'customer'
+    request.userType = UserType.CUSTOMER
    request.userId = customer.id
    return
  }
  const mitra = await getMitraByFirebaseUid(request.firebaseUser.uid)
  if (mitra) {
-    request.userType = 'mitra'
+    request.userType = UserType.MITRA
    request.userId = mitra.id
    return
  }
@@ -24,9 +28,25 @@ const resolveUser = async (request, reply) => {
  })
 }

+// Verify session belongs to the authenticated user
+const verifySessionOwnership = async (request, reply) => {
+  const { sessionId } = request.params
+  const [session] = await sql`
+    SELECT id FROM chat_sessions
+    WHERE id = ${sessionId}
+      AND (customer_id = ${request.userId} OR mitra_id = ${request.userId})
+  `
+  if (!session) {
+    return reply.code(403).send({
+      success: false,
+      error: { code: 'FORBIDDEN', message: 'You do not have access to this session' },
+    })
+  }
+}
+
 export const sharedChatRoutes = async (app) => {
  // Get messages for a session (paginated)
-  app.get('/chat/:sessionId/messages', { preHandler: [authenticate, resolveUser] }, async (request, reply) => {
+  app.get('/chat/:sessionId/messages', { preHandler: [authenticate, resolveUser, verifySessionOwnership] }, async (request, reply) => {
    const { sessionId } = request.params
    const { limit, before } = request.query
    const messages = await getMessages(sessionId, {
@@ -37,7 +57,7 @@ export const sharedChatRoutes = async (app) => {
  })

  // Get session info
-  app.get('/chat/:sessionId/info', { preHandler: [authenticate, resolveUser] }, async (request, reply) => {
+  app.get('/chat/:sessionId/info', { preHandler: [authenticate, resolveUser, verifySessionOwnership] }, async (request, reply) => {
    const { sessionId } = request.params
    const { getSessionById } = await import('../../services/session.service.js')
    const session = await getSessionById(sessionId)
@@ -48,7 +68,7 @@ export const sharedChatRoutes = async (app) => {
  })

  // Get full transcript (read-only, for history)
-  app.get('/chat/:sessionId/transcript', { preHandler: [authenticate, resolveUser] }, async (request, reply) => {
+  app.get('/chat/:sessionId/transcript', { preHandler: [authenticate, resolveUser, verifySessionOwnership] }, async (request, reply) => {
    const { sessionId } = request.params
    const messages = await getMessages(sessionId, { limit: 10000 })
    const closures = await getSessionClosures(sessionId)
@@ -66,7 +86,7 @@ export const sharedChatRoutes = async (app) => {
  })

  // Submit goodbye/closure message
-  app.post('/sessions/:sessionId/close-message', { preHandler: [authenticate, resolveUser] }, async (request, reply) => {
+  app.post('/sessions/:sessionId/close-message', { preHandler: [authenticate, resolveUser, verifySessionOwnership] }, async (request, reply) => {
    const { sessionId } = request.params
    const { message } = request.body
    if (!message) {
--- a/backend/src/services/chat-handler.service.js
+++ b/backend/src/services/chat-handler.service.js
@@ -2,6 +2,7 @@ import { subscribe } from '../plugins/valkey.js'
 import { sendMessage, markDelivered, markRead } from './chat.service.js'
 import { initiateEarlyEnd } from './closure.service.js'
 import { sendToSessionParticipant } from '../plugins/websocket.js'
+import { UserType, MessageType, WsMessage } from '../constants.js'

 // Track typing throttle per session+user
 const typingLastSent = new Map()
@@ -18,36 +19,36 @@ export const startSessionListener = (sessionId) => {

    try {
      switch (type) {
-        case 'message':
+        case WsMessage.MESSAGE:
          await sendMessage({
            sessionId: _session_id,
            senderType: _sender_type,
            senderId: _sender_id,
            content: payload.content,
-            type: payload.message_type || 'text',
+            type: payload.message_type || MessageType.TEXT,
          })
          break

-        case 'typing':
+        case WsMessage.TYPING:
          handleTyping(_session_id, _sender_type)
          break

-        case 'delivered':
+        case WsMessage.DELIVERED:
          await markDelivered(_session_id, _sender_type, payload.message_ids)
          break

-        case 'read':
+        case WsMessage.READ:
          await markRead(_session_id, _sender_type, payload.message_ids)
          break

-        case 'early_end':
+        case WsMessage.EARLY_END:
          await initiateEarlyEnd(_session_id, _sender_type)
          break
      }
    } catch (err) {
      console.error(`[chat-handler] Error processing ${type}:`, err.message)
      sendToSessionParticipant(_session_id, _sender_type, {
-        type: 'error',
+        type: WsMessage.ERROR,
        message: err.message,
        code: err.code,
      })
@@ -74,9 +75,9 @@ const handleTyping = (sessionId, senderType) => {

  typingLastSent.set(key, now)

-  const recipientType = senderType === 'customer' ? 'mitra' : 'customer'
+  const recipientType = senderType === UserType.CUSTOMER ? UserType.MITRA : UserType.CUSTOMER
  sendToSessionParticipant(sessionId, recipientType, {
-    type: 'typing',
+    type: WsMessage.TYPING,
    sender_type: senderType,
  })
 }
--- a/backend/src/services/chat.service.js
+++ b/backend/src/services/chat.service.js
@@ -2,14 +2,15 @@ import { getDb } from '../db/client.js'
 import { publish } from '../plugins/valkey.js'
 import { isUserOnlineWs, sendToSessionParticipant } from '../plugins/websocket.js'
 import { sendPushNotification } from './notification.service.js'
+import { UserType, SessionStatus, MessageStatus, MessageType, WsMessage } from '../constants.js'

 const sql = getDb()

-export const sendMessage = async ({ sessionId, senderType, senderId, content, type = 'text' }) => {
+export const sendMessage = async ({ sessionId, senderType, senderId, content, type = MessageType.TEXT }) => {
  // Verify session is active
  const [session] = await sql`
    SELECT id, customer_id, mitra_id, status FROM chat_sessions
-    WHERE id = ${sessionId} AND status = 'active'
+    WHERE id = ${sessionId} AND status = ${SessionStatus.ACTIVE}
  `
  if (!session) {
    throw Object.assign(new Error('Session is not active'), {
@@ -20,25 +21,25 @@ export const sendMessage = async ({ sessionId, senderType, senderId, content, ty
  // Save message
  const [message] = await sql`
    INSERT INTO chat_messages (session_id, sender_type, sender_id, type, content, status)
-    VALUES (${sessionId}, ${senderType}, ${senderId}, ${type}, ${content}, 'sent')
+    VALUES (${sessionId}, ${senderType}, ${senderId}, ${type}, ${content}, ${MessageStatus.SENT})
    RETURNING id, session_id, sender_type, sender_id, type, content, status, created_at
  `

  // Send ack to sender
  sendToSessionParticipant(sessionId, senderType, {
-    type: 'message_ack',
+    type: WsMessage.MESSAGE_ACK,
    message_id: message.id,
-    status: 'sent',
+    status: MessageStatus.SENT,
    created_at: message.created_at,
  })

  // Determine recipient
-  const recipientType = senderType === 'customer' ? 'mitra' : 'customer'
-  const recipientId = senderType === 'customer' ? session.mitra_id : session.customer_id
+  const recipientType = senderType === UserType.CUSTOMER ? UserType.MITRA : UserType.CUSTOMER
+  const recipientId = senderType === UserType.CUSTOMER ? session.mitra_id : session.customer_id

  // Try to send via WebSocket
  const delivered = sendToSessionParticipant(sessionId, recipientType, {
-    type: 'message',
+    type: WsMessage.MESSAGE,
    message_id: message.id,
    sender_type: senderType,
    content: message.content,
@@ -49,7 +50,7 @@ export const sendMessage = async ({ sessionId, senderType, senderId, content, ty
  // If recipient not connected via WebSocket, send FCM push
  if (!delivered && recipientId) {
    await sendPushNotification(recipientType, recipientId, {
-      title: senderType === 'customer' ? 'Pesan baru dari Customer' : 'Pesan baru dari Bestie',
+      title: senderType === UserType.CUSTOMER ? 'Pesan baru dari Customer' : 'Pesan baru dari Bestie',
      body: content.length > 100 ? content.substring(0, 100) + '...' : content,
      data: { session_id: sessionId, type: 'chat_message' },
    })
@@ -63,18 +64,18 @@ export const markDelivered = async (sessionId, senderType, messageIds) => {

  await sql`
    UPDATE chat_messages
-    SET status = 'delivered', delivered_at = NOW()
+    SET status = ${MessageStatus.DELIVERED}, delivered_at = NOW()
    WHERE id = ANY(${messageIds})
      AND session_id = ${sessionId}
-      AND status = 'sent'
+      AND status = ${MessageStatus.SENT}
  `

  // Notify sender about delivery
-  const recipientType = senderType === 'customer' ? 'mitra' : 'customer'
+  const recipientType = senderType === UserType.CUSTOMER ? UserType.MITRA : UserType.CUSTOMER
  sendToSessionParticipant(sessionId, recipientType, {
-    type: 'message_status',
+    type: WsMessage.MESSAGE_STATUS,
    message_ids: messageIds,
-    status: 'delivered',
+    status: MessageStatus.DELIVERED,
  })
 }

@@ -83,18 +84,18 @@ export const markRead = async (sessionId, senderType, messageIds) => {

  await sql`
    UPDATE chat_messages
-    SET status = 'read', read_at = NOW()
+    SET status = ${MessageStatus.READ}, read_at = NOW()
    WHERE id = ANY(${messageIds})
      AND session_id = ${sessionId}
-      AND status IN ('sent', 'delivered')
+      AND status IN (${MessageStatus.SENT}, ${MessageStatus.DELIVERED})
  `

  // Notify sender about read
-  const recipientType = senderType === 'customer' ? 'mitra' : 'customer'
+  const recipientType = senderType === UserType.CUSTOMER ? UserType.MITRA : UserType.CUSTOMER
  sendToSessionParticipant(sessionId, recipientType, {
-    type: 'message_status',
+    type: WsMessage.MESSAGE_STATUS,
    message_ids: messageIds,
-    status: 'read',
+    status: MessageStatus.READ,
  })
 }

@@ -115,13 +116,13 @@ export const getMessages = async (sessionId, { limit = 50, before } = {}) => {
 }

 export const getUndeliveredMessages = async (sessionId, recipientType) => {
-  const senderType = recipientType === 'customer' ? 'mitra' : 'customer'
+  const senderType = recipientType === UserType.CUSTOMER ? UserType.MITRA : UserType.CUSTOMER
  return sql`
    SELECT id, session_id, sender_type, sender_id, type, content, status, created_at
    FROM chat_messages
    WHERE session_id = ${sessionId}
      AND sender_type = ${senderType}
-      AND status = 'sent'
+      AND status = ${MessageStatus.SENT}
    ORDER BY created_at ASC
  `
 }
--- a/backend/src/services/closure.service.js
+++ b/backend/src/services/closure.service.js
@@ -1,7 +1,8 @@
 import { getDb } from '../db/client.js'
 import { publish } from '../plugins/valkey.js'
-import { clearSessionTimer } from './session-timer.service.js'
+import { clearSessionTimer, clearClosureGraceTimer } from './session-timer.service.js'
 import { sendToSessionParticipant } from '../plugins/websocket.js'
+import { UserType, SessionStatus, EndedBy, WsMessage } from '../constants.js'

 const sql = getDb()

@@ -9,7 +10,7 @@ export const submitClosureMessage = async (sessionId, userType, userId, message)
  // Verify session is in closing or active state (for early end)
  const [session] = await sql`
    SELECT id, status FROM chat_sessions
-    WHERE id = ${sessionId} AND status IN ('closing', 'active', 'extending')
+    WHERE id = ${sessionId} AND status IN (${SessionStatus.CLOSING}, ${SessionStatus.ACTIVE}, ${SessionStatus.EXTENDING})
  `
  if (!session) {
    throw Object.assign(new Error('Session not found or already completed'), {
@@ -29,8 +30,8 @@ export const submitClosureMessage = async (sessionId, userType, userId, message)
  const closures = await sql`
    SELECT user_type FROM session_closures WHERE session_id = ${sessionId}
  `
-  const hasCustomer = closures.some((c) => c.user_type === 'customer')
-  const hasMitra = closures.some((c) => c.user_type === 'mitra')
+  const hasCustomer = closures.some((c) => c.user_type === UserType.CUSTOMER)
+  const hasMitra = closures.some((c) => c.user_type === UserType.MITRA)

  if (hasCustomer && hasMitra) {
    // Both submitted — complete the session
@@ -42,28 +43,29 @@ export const submitClosureMessage = async (sessionId, userType, userId, message)

 export const completeSession = async (sessionId) => {
  clearSessionTimer(sessionId)
+  clearClosureGraceTimer(sessionId)

  const [session] = await sql`
    UPDATE chat_sessions
-    SET status = 'completed', ended_at = NOW(), ended_by = 'system'
-    WHERE id = ${sessionId} AND status IN ('closing', 'active', 'extending')
+    SET status = ${SessionStatus.COMPLETED}, ended_at = NOW(), ended_by = ${EndedBy.SYSTEM}
+    WHERE id = ${sessionId} AND status IN (${SessionStatus.CLOSING}, ${SessionStatus.ACTIVE}, ${SessionStatus.EXTENDING})
    RETURNING id, customer_id, mitra_id, status, ended_at
  `
  if (!session) return null

  // Notify both parties
-  const data = { type: 'session_completed', session_id: sessionId }
-  sendToSessionParticipant(sessionId, 'customer', data)
-  sendToSessionParticipant(sessionId, 'mitra', data)
+  const data = { type: WsMessage.SESSION_COMPLETED, session_id: sessionId }
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, data)
+  sendToSessionParticipant(sessionId, UserType.MITRA, data)

-  await publish(`session:${sessionId}:status`, { type: 'session_ended', session_id: sessionId })
+  await publish(`session:${sessionId}:status`, { type: WsMessage.SESSION_ENDED, session_id: sessionId })

  return session
 }

 export const initiateEarlyEnd = async (sessionId, userType) => {
  // Check if early end is enabled for this user type
-  const configKey = userType === 'mitra' ? 'early_end_mitra_enabled' : 'early_end_customer_enabled'
+  const configKey = userType === UserType.MITRA ? 'early_end_mitra_enabled' : 'early_end_customer_enabled'
  const [configRow] = await sql`SELECT value FROM app_config WHERE key = ${configKey}`
  const enabled = configRow?.value?.value ?? false

@@ -76,8 +78,8 @@ export const initiateEarlyEnd = async (sessionId, userType) => {
  // Move session to closing
  const [session] = await sql`
    UPDATE chat_sessions
-    SET status = 'closing', ended_by = ${userType}
-    WHERE id = ${sessionId} AND status = 'active'
+    SET status = ${SessionStatus.CLOSING}, ended_by = ${userType}
+    WHERE id = ${sessionId} AND status = ${SessionStatus.ACTIVE}
    RETURNING id, customer_id, mitra_id
  `
  if (!session) {
@@ -89,9 +91,9 @@ export const initiateEarlyEnd = async (sessionId, userType) => {
  clearSessionTimer(sessionId)

  // Notify both parties to enter closure flow
-  const data = { type: 'session_closing', session_id: sessionId, ended_by: userType }
-  sendToSessionParticipant(sessionId, 'customer', data)
-  sendToSessionParticipant(sessionId, 'mitra', data)
+  const data = { type: WsMessage.SESSION_CLOSING, session_id: sessionId, ended_by: userType }
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, data)
+  sendToSessionParticipant(sessionId, UserType.MITRA, data)

  return session
 }
--- a/backend/src/services/dashboard.service.js
+++ b/backend/src/services/dashboard.service.js
@@ -1,18 +1,19 @@
 import { getDb } from '../db/client.js'
+import { SessionStatus } from '../constants.js'

 const sql = getDb()

 export const getDashboardStats = async () => {
  const [[{ active_chats }], [{ online_mitras }], [{ pending_requests }]] = await Promise.all([
-    sql`SELECT COUNT(*) AS active_chats FROM chat_sessions WHERE status IN ('active', 'pending_payment')`,
+    sql`SELECT COUNT(*) AS active_chats FROM chat_sessions WHERE status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})`,
    sql`SELECT COUNT(*) AS online_mitras FROM mitra_online_status WHERE is_online = true`,
-    sql`SELECT COUNT(*) AS pending_requests FROM chat_sessions WHERE status IN ('searching', 'pending_acceptance')`,
+    sql`SELECT COUNT(*) AS pending_requests FROM chat_sessions WHERE status IN (${SessionStatus.SEARCHING}, ${SessionStatus.PENDING_ACCEPTANCE})`,
  ])

  const customersPerMitra = await sql`
    SELECT m.id, m.display_name,
      (SELECT COUNT(*) FROM chat_sessions cs
-       WHERE cs.mitra_id = m.id AND cs.status IN ('active', 'pending_payment')) AS active_session_count
+       WHERE cs.mitra_id = m.id AND cs.status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})) AS active_session_count
    FROM mitras m
    INNER JOIN mitra_online_status s ON s.mitra_id = m.id
    WHERE s.is_online = true
--- a/backend/src/services/extension.service.js
+++ b/backend/src/services/extension.service.js
@@ -1,7 +1,8 @@
 import { getDb } from '../db/client.js'
 import { publish } from '../plugins/valkey.js'
 import { sendToSessionParticipant } from '../plugins/websocket.js'
-import { extendSessionTimer } from './session-timer.service.js'
+import { extendSessionTimer, clearClosureGraceTimer } from './session-timer.service.js'
+import { UserType, SessionStatus, ExtensionStatus, TransactionType, WsMessage } from '../constants.js'

 const sql = getDb()

@@ -14,28 +15,29 @@ const getExtensionTimeout = async () => {
 }

 export const requestExtension = async (sessionId, customerId, { duration_minutes, price }) => {
-  // Verify session belongs to customer and just expired
+  // Verify session belongs to customer and is in an extendable state
  const [session] = await sql`
    SELECT id, customer_id, mitra_id, status FROM chat_sessions
    WHERE id = ${sessionId} AND customer_id = ${customerId}
+      AND status IN (${SessionStatus.ACTIVE}, ${SessionStatus.CLOSING})
  `
  if (!session) {
-    throw Object.assign(new Error('Session not found'), { code: 'NOT_FOUND', statusCode: 404 })
+    throw Object.assign(new Error('Session not found or already ended'), { code: 'SESSION_NOT_ACTIVE', statusCode: 409 })
  }

  // Create extension record
  const [extension] = await sql`
    INSERT INTO session_extensions (session_id, requested_duration_minutes, requested_price, status)
-    VALUES (${sessionId}, ${duration_minutes}, ${price}, 'pending')
+    VALUES (${sessionId}, ${duration_minutes}, ${price}, ${ExtensionStatus.PENDING})
    RETURNING id, session_id, requested_duration_minutes, requested_price, status, requested_at
  `

  // Pause the session
-  await sql`UPDATE chat_sessions SET status = 'extending' WHERE id = ${sessionId}`
+  await sql`UPDATE chat_sessions SET status = ${SessionStatus.EXTENDING} WHERE id = ${sessionId}`

  // Notify mitra
-  sendToSessionParticipant(sessionId, 'mitra', {
-    type: 'extension_request',
+  sendToSessionParticipant(sessionId, UserType.MITRA, {
+    type: WsMessage.EXTENSION_REQUEST,
    extension_id: extension.id,
    session_id: sessionId,
    duration_minutes,
@@ -43,8 +45,8 @@ export const requestExtension = async (sessionId, customerId, { duration_minutes
  })

  // Notify customer that chat is paused
-  sendToSessionParticipant(sessionId, 'customer', {
-    type: 'session_paused',
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+    type: WsMessage.SESSION_PAUSED,
    session_id: sessionId,
    reason: 'extension_pending',
  })
@@ -62,12 +64,20 @@ export const requestExtension = async (sessionId, customerId, { duration_minutes
 }

 export const respondToExtension = async (extensionId, sessionId, mitraId, accepted) => {
-  const status = accepted ? 'accepted' : 'rejected'
+  // Verify session belongs to this mitra
+  const [session] = await sql`
+    SELECT id FROM chat_sessions WHERE id = ${sessionId} AND mitra_id = ${mitraId}
+  `
+  if (!session) {
+    throw Object.assign(new Error('Session not found'), { code: 'FORBIDDEN', statusCode: 403 })
+  }
+
+  const status = accepted ? ExtensionStatus.ACCEPTED : ExtensionStatus.REJECTED

  const [extension] = await sql`
    UPDATE session_extensions
    SET status = ${status}, responded_at = NOW()
-    WHERE id = ${extensionId} AND status = 'pending'
+    WHERE id = ${extensionId} AND session_id = ${sessionId} AND status = ${ExtensionStatus.PENDING}
    RETURNING id, session_id, requested_duration_minutes, requested_price, status
  `

@@ -85,43 +95,50 @@ export const respondToExtension = async (extensionId, sessionId, mitraId, accept
  }

  if (accepted) {
+    // Clear any pending grace timer from the previous expiry
+    clearClosureGraceTimer(sessionId)
+
    // Extend the session
    await extendSessionTimer(extension.session_id, extension.requested_duration_minutes)

    // Resume session
-    await sql`UPDATE chat_sessions SET status = 'active' WHERE id = ${extension.session_id}`
+    await sql`UPDATE chat_sessions SET status = ${SessionStatus.ACTIVE} WHERE id = ${extension.session_id}`

    // Record transaction
    await sql`
      INSERT INTO customer_transactions (customer_id, session_id, type, amount)
-      SELECT customer_id, id, 'extension', ${extension.requested_price}
+      SELECT customer_id, id, ${TransactionType.EXTENSION}, ${extension.requested_price}
      FROM chat_sessions WHERE id = ${extension.session_id}
    `

    // Notify both parties
-    sendToSessionParticipant(sessionId, 'customer', {
-      type: 'extension_response',
+    sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+      type: WsMessage.EXTENSION_RESPONSE,
      accepted: true,
      duration_minutes: extension.requested_duration_minutes,
    })
-    sendToSessionParticipant(sessionId, 'mitra', {
-      type: 'session_resumed',
+    sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+      type: WsMessage.SESSION_RESUMED,
+      session_id: sessionId,
+    })
+    sendToSessionParticipant(sessionId, UserType.MITRA, {
+      type: WsMessage.SESSION_RESUMED,
      session_id: sessionId,
    })
  } else {
    // Rejected — proceed to closure
-    await sql`UPDATE chat_sessions SET status = 'closing' WHERE id = ${extension.session_id}`
+    await sql`UPDATE chat_sessions SET status = ${SessionStatus.CLOSING} WHERE id = ${extension.session_id}`

-    sendToSessionParticipant(sessionId, 'customer', {
-      type: 'extension_response',
+    sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+      type: WsMessage.EXTENSION_RESPONSE,
      accepted: false,
    })
-    sendToSessionParticipant(sessionId, 'mitra', {
-      type: 'session_closing',
+    sendToSessionParticipant(sessionId, UserType.MITRA, {
+      type: WsMessage.SESSION_CLOSING,
      session_id: sessionId,
    })
-    sendToSessionParticipant(sessionId, 'customer', {
-      type: 'session_closing',
+    sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+      type: WsMessage.SESSION_CLOSING,
      session_id: sessionId,
    })
  }
@@ -134,26 +151,26 @@ const timeoutExtension = async (extensionId, sessionId) => {

  const [extension] = await sql`
    UPDATE session_extensions
-    SET status = 'timeout', responded_at = NOW()
-    WHERE id = ${extensionId} AND status = 'pending'
+    SET status = ${ExtensionStatus.TIMEOUT}, responded_at = NOW()
+    WHERE id = ${extensionId} AND status = ${ExtensionStatus.PENDING}
    RETURNING id, session_id
  `
  if (!extension) return

  // Timeout = proceed to closure
-  await sql`UPDATE chat_sessions SET status = 'closing' WHERE id = ${extension.session_id}`
+  await sql`UPDATE chat_sessions SET status = ${SessionStatus.CLOSING} WHERE id = ${extension.session_id}`

-  sendToSessionParticipant(sessionId, 'customer', {
-    type: 'extension_response',
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+    type: WsMessage.EXTENSION_RESPONSE,
    accepted: false,
    reason: 'timeout',
  })
-  sendToSessionParticipant(sessionId, 'mitra', {
-    type: 'session_closing',
+  sendToSessionParticipant(sessionId, UserType.MITRA, {
+    type: WsMessage.SESSION_CLOSING,
    session_id: sessionId,
  })
-  sendToSessionParticipant(sessionId, 'customer', {
-    type: 'session_closing',
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, {
+    type: WsMessage.SESSION_CLOSING,
    session_id: sessionId,
  })
 }
--- a/backend/src/services/mitra-status.service.js
+++ b/backend/src/services/mitra-status.service.js
@@ -1,4 +1,5 @@
 import { getDb } from '../db/client.js'
+import { SessionStatus } from '../constants.js'

 const sql = getDb()

@@ -64,7 +65,7 @@ export const getOnlineMitras = async () => {
  const mitras = await sql`
    SELECT m.id, m.display_name, m.phone, s.last_online_at, s.updated_at,
      (SELECT COUNT(*) FROM chat_sessions cs
-       WHERE cs.mitra_id = m.id AND cs.status IN ('active', 'pending_payment')) AS active_session_count
+       WHERE cs.mitra_id = m.id AND cs.status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})) AS active_session_count
    FROM mitras m
    INNER JOIN mitra_online_status s ON s.mitra_id = m.id
    WHERE s.is_online = true AND m.is_active = true
--- a/backend/src/services/notification.service.js
+++ b/backend/src/services/notification.service.js
@@ -1,10 +1,11 @@
 import admin from 'firebase-admin'
 import { getDb } from '../db/client.js'
+import { UserType } from '../constants.js'

 const sql = getDb()

 export const registerDeviceToken = async (userType, userId, fcmToken) => {
-  const table = userType === 'customer' ? 'customers' : 'mitras'
+  const table = userType === UserType.CUSTOMER ? 'customers' : 'mitras'
  await sql`
    UPDATE ${sql(table)}
    SET fcm_token = ${fcmToken}
@@ -13,7 +14,7 @@ export const registerDeviceToken = async (userType, userId, fcmToken) => {
 }

 export const sendPushNotification = async (recipientType, recipientId, { title, body, data = {} }) => {
-  const table = recipientType === 'customer' ? 'customers' : 'mitras'
+  const table = recipientType === UserType.CUSTOMER ? 'customers' : 'mitras'
  const [user] = await sql`
    SELECT fcm_token FROM ${sql(table)} WHERE id = ${recipientId}
  `
--- a/backend/src/services/pairing.service.js
+++ b/backend/src/services/pairing.service.js
@@ -1,14 +1,51 @@
 import { getDb } from '../db/client.js'
 import { getMaxCustomersPerMitra } from './config.service.js'
-import { publish } from '../plugins/valkey.js'
+import { sendToUser } from '../plugins/websocket.js'
+import { sendPushNotification } from './notification.service.js'
 import { startSessionTimer } from './session-timer.service.js'
 import { startSessionListener } from './chat-handler.service.js'
+import { UserType, SessionStatus, NotificationResponse, TransactionType, WsMessage } from '../constants.js'

 const sql = getDb()

 // Timeout map for active pairing requests (sessionId → timeoutId)
 const pairingTimeouts = new Map()

+// Send notification to mitra via WebSocket, fall back to FCM if offline
+const notifyMitra = async (mitraId, data) => {
+  const sent = sendToUser(UserType.MITRA, mitraId, data)
+  if (!sent) {
+    // Mitra not connected via WebSocket — send FCM push
+    if (data.type === WsMessage.CHAT_REQUEST) {
+      await sendPushNotification(UserType.MITRA, mitraId, {
+        title: 'Permintaan Chat Baru',
+        body: 'Ada pelanggan yang ingin curhat!',
+        data: { type: WsMessage.CHAT_REQUEST, session_id: data.session_id },
+      })
+    }
+  }
+}
+
+// Send notification to customer via WebSocket, fall back to FCM if offline
+const notifyCustomer = async (customerId, data) => {
+  const sent = sendToUser(UserType.CUSTOMER, customerId, data)
+  if (!sent) {
+    if (data.type === WsMessage.PAIRED) {
+      await sendPushNotification(UserType.CUSTOMER, customerId, {
+        title: 'Bestie Ditemukan!',
+        body: `${data.mitra_display_name} siap menemanimu curhat`,
+        data: { type: WsMessage.PAIRED, session_id: data.session_id },
+      })
+    } else if (data.type === WsMessage.SESSION_EXPIRED) {
+      await sendPushNotification(UserType.CUSTOMER, customerId, {
+        title: 'Tidak Ada Bestie',
+        body: 'Maaf, tidak ada bestie yang tersedia saat ini.',
+        data: { type: WsMessage.SESSION_EXPIRED, session_id: data.session_id },
+      })
+    }
+  }
+}
+
 export const findAvailableMitras = async () => {
  const { max_customers_per_mitra } = await getMaxCustomersPerMitra()
  const mitras = await sql`
@@ -19,7 +56,7 @@ export const findAvailableMitras = async () => {
      AND s.is_online = true
      AND (
        SELECT COUNT(*) FROM chat_sessions cs
-        WHERE cs.mitra_id = m.id AND cs.status IN ('active', 'pending_payment')
+        WHERE cs.mitra_id = m.id AND cs.status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})
      ) < ${max_customers_per_mitra}
  `
  return mitras
@@ -30,7 +67,7 @@ export const createPairingRequest = async (customerId, { duration_minutes, price
  const [existing] = await sql`
    SELECT id, status FROM chat_sessions
    WHERE customer_id = ${customerId}
-      AND status IN ('searching', 'pending_acceptance', 'pending_payment', 'active')
+      AND status IN (${SessionStatus.SEARCHING}, ${SessionStatus.PENDING_ACCEPTANCE}, ${SessionStatus.PENDING_PAYMENT}, ${SessionStatus.ACTIVE})
  `
  if (existing) {
    throw Object.assign(new Error('Customer already has an active session or request'), {
@@ -48,7 +85,7 @@ export const createPairingRequest = async (customerId, { duration_minutes, price
  // Create session with duration/price
  const [session] = await sql`
    INSERT INTO chat_sessions (customer_id, status, duration_minutes, price, is_free_trial)
-    VALUES (${customerId}, 'pending_acceptance', ${duration_minutes || null}, ${price || 0}, ${is_free_trial || false})
+    VALUES (${customerId}, ${SessionStatus.PENDING_ACCEPTANCE}, ${duration_minutes || null}, ${price || 0}, ${is_free_trial || false})
    RETURNING id, customer_id, status, duration_minutes, price, is_free_trial, created_at
  `

@@ -58,9 +95,9 @@ export const createPairingRequest = async (customerId, { duration_minutes, price
      INSERT INTO chat_request_notifications (session_id, mitra_id)
      VALUES (${session.id}, ${mitra.id})
    `
-    // Publish to mitra's channel
-    await publish(`mitra:${mitra.id}:requests`, {
-      type: 'chat_request',
+    // Notify mitra via WebSocket (FCM fallback if offline)
+    await notifyMitra(mitra.id, {
+      type: WsMessage.CHAT_REQUEST,
      session_id: session.id,
      created_at: session.created_at,
    })
@@ -81,8 +118,8 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
  // Use a transaction-like approach: update only if status is still pending_acceptance
  const [session] = await sql`
    UPDATE chat_sessions
-    SET mitra_id = ${mitraId}, status = 'pending_payment', paired_at = NOW()
-    WHERE id = ${sessionId} AND status = 'pending_acceptance' AND mitra_id IS NULL
+    SET mitra_id = ${mitraId}, status = ${SessionStatus.PENDING_PAYMENT}, paired_at = NOW()
+    WHERE id = ${sessionId} AND status = ${SessionStatus.PENDING_ACCEPTANCE} AND mitra_id IS NULL
    RETURNING id, customer_id, mitra_id, status, paired_at
  `

@@ -95,14 +132,14 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
  // Mark this mitra's notification as accepted
  await sql`
    UPDATE chat_request_notifications
-    SET response = 'accepted', responded_at = NOW()
+    SET response = ${NotificationResponse.ACCEPTED}, responded_at = NOW()
    WHERE session_id = ${sessionId} AND mitra_id = ${mitraId}
  `

  // Mark other mitras' notifications as ignored
  await sql`
    UPDATE chat_request_notifications
-    SET response = 'ignored', responded_at = NOW()
+    SET response = ${NotificationResponse.IGNORED}, responded_at = NOW()
    WHERE session_id = ${sessionId} AND mitra_id != ${mitraId} AND response IS NULL
  `

@@ -116,7 +153,7 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
  // Auto-skip payment for now: move to active and set expires_at
  const [activeSession] = await sql`
    UPDATE chat_sessions
-    SET status = 'active',
+    SET status = ${SessionStatus.ACTIVE},
        expires_at = CASE
          WHEN duration_minutes IS NOT NULL THEN NOW() + (duration_minutes || ' minutes')::interval
          ELSE NULL
@@ -127,7 +164,7 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {

  // Record transaction
  if (activeSession.duration_minutes) {
-    const txType = activeSession.is_free_trial ? 'free_trial' : 'paid'
+    const txType = activeSession.is_free_trial ? TransactionType.FREE_TRIAL : TransactionType.PAID
    await sql`
      INSERT INTO customer_transactions (customer_id, session_id, type, amount)
      VALUES (${activeSession.customer_id}, ${sessionId}, ${txType}, ${activeSession.price || 0})
@@ -147,12 +184,12 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
    SELECT display_name FROM mitras WHERE id = ${mitraId}
  `

-  // Notify customer
-  await publish(`session:${sessionId}:status`, {
-    type: 'paired',
+  // Notify customer via WebSocket (FCM fallback)
+  await notifyCustomer(activeSession.customer_id, {
+    type: WsMessage.PAIRED,
    session_id: sessionId,
    mitra_display_name: mitra.display_name,
-    status: 'active',
+    status: SessionStatus.ACTIVE,
  })

  // Notify other mitras to dismiss the request
@@ -161,8 +198,8 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
    WHERE session_id = ${sessionId} AND mitra_id != ${mitraId}
  `
  for (const n of notifications) {
-    await publish(`mitra:${n.mitra_id}:requests`, {
-      type: 'chat_request_closed',
+    await notifyMitra(n.mitra_id, {
+      type: WsMessage.CHAT_REQUEST_CLOSED,
      session_id: sessionId,
    })
  }
@@ -173,7 +210,7 @@ export const acceptPairingRequest = async (sessionId, mitraId) => {
 export const declinePairingRequest = async (sessionId, mitraId) => {
  await sql`
    UPDATE chat_request_notifications
-    SET response = 'declined', responded_at = NOW()
+    SET response = ${NotificationResponse.DECLINED}, responded_at = NOW()
    WHERE session_id = ${sessionId} AND mitra_id = ${mitraId} AND response IS NULL
  `
 }
@@ -181,9 +218,9 @@ export const declinePairingRequest = async (sessionId, mitraId) => {
 export const cancelPairingRequest = async (sessionId, customerId) => {
  const [session] = await sql`
    UPDATE chat_sessions
-    SET status = 'cancelled'
+    SET status = ${SessionStatus.CANCELLED}
    WHERE id = ${sessionId} AND customer_id = ${customerId}
-      AND status IN ('searching', 'pending_acceptance')
+      AND status IN (${SessionStatus.SEARCHING}, ${SessionStatus.PENDING_ACCEPTANCE})
    RETURNING id, status
  `

@@ -203,7 +240,7 @@ export const cancelPairingRequest = async (sessionId, customerId) => {
  // Mark all notifications as ignored
  await sql`
    UPDATE chat_request_notifications
-    SET response = 'ignored', responded_at = NOW()
+    SET response = ${NotificationResponse.IGNORED}, responded_at = NOW()
    WHERE session_id = ${sessionId} AND response IS NULL
  `

@@ -212,8 +249,8 @@ export const cancelPairingRequest = async (sessionId, customerId) => {
    SELECT mitra_id FROM chat_request_notifications WHERE session_id = ${sessionId}
  `
  for (const n of notifications) {
-    await publish(`mitra:${n.mitra_id}:requests`, {
-      type: 'chat_request_closed',
+    await notifyMitra(n.mitra_id, {
+      type: WsMessage.CHAT_REQUEST_CLOSED,
      session_id: sessionId,
    })
  }
@@ -224,8 +261,8 @@ export const cancelPairingRequest = async (sessionId, customerId) => {
 export const expirePairingRequest = async (sessionId) => {
  const [session] = await sql`
    UPDATE chat_sessions
-    SET status = 'expired'
-    WHERE id = ${sessionId} AND status = 'pending_acceptance'
+    SET status = ${SessionStatus.EXPIRED}
+    WHERE id = ${sessionId} AND status = ${SessionStatus.PENDING_ACCEPTANCE}
    RETURNING id, customer_id, status
  `
  if (!session) return null
@@ -235,13 +272,13 @@ export const expirePairingRequest = async (sessionId) => {
  // Mark all pending notifications as ignored
  await sql`
    UPDATE chat_request_notifications
-    SET response = 'ignored', responded_at = NOW()
+    SET response = ${NotificationResponse.IGNORED}, responded_at = NOW()
    WHERE session_id = ${sessionId} AND response IS NULL
  `

-  // Notify customer
-  await publish(`session:${sessionId}:status`, {
-    type: 'expired',
+  // Notify customer via WebSocket (FCM fallback)
+  await notifyCustomer(session.customer_id, {
+    type: WsMessage.SESSION_EXPIRED,
    session_id: sessionId,
  })

@@ -250,8 +287,8 @@ export const expirePairingRequest = async (sessionId) => {
    SELECT mitra_id FROM chat_request_notifications WHERE session_id = ${sessionId}
  `
  for (const n of notifications) {
-    await publish(`mitra:${n.mitra_id}:requests`, {
-      type: 'chat_request_closed',
+    await notifyMitra(n.mitra_id, {
+      type: WsMessage.CHAT_REQUEST_CLOSED,
      session_id: sessionId,
    })
  }
--- a/backend/src/services/pricing.service.js
+++ b/backend/src/services/pricing.service.js
@@ -2,8 +2,9 @@ import { getDb } from '../db/client.js'

 const sql = getDb()

-// Mock price tiers (will come from Control Center config later)
-const PRICE_TIERS = [
+// Default tiers as fallback
+const DEFAULT_TIERS = [
+  { duration_minutes: 1, price: 5000, label: '1 Menit (Test)' },
  { duration_minutes: 15, price: 30000, label: '15 Menit' },
  { duration_minutes: 30, price: 60000, label: '30 Menit' },
  { duration_minutes: 45, price: 100000, label: '45 Menit' },
@@ -11,10 +12,14 @@ const PRICE_TIERS = [
  { duration_minutes: 1440, price: 250000, label: '24 Jam' },
 ]

-export const getPriceTiers = () => PRICE_TIERS
+export const getPriceTiers = async () => {
+  const [row] = await sql`SELECT value FROM app_config WHERE key = 'price_tiers'`
+  return row?.value?.tiers ?? DEFAULT_TIERS
+}

-export const isValidTier = (durationMinutes, price) => {
-  return PRICE_TIERS.some(
+export const isValidTier = async (durationMinutes, price) => {
+  const tiers = await getPriceTiers()
+  return tiers.some(
    (t) => t.duration_minutes === durationMinutes && t.price === price
  )
 }
@@ -41,7 +46,7 @@ export const isCustomerEligibleForFreeTrial = async (customerId) => {
 }

 export const getPricingForCustomer = async (customerId) => {
-  const tiers = getPriceTiers()
+  const tiers = await getPriceTiers()
  const freeTrialEligible = await isCustomerEligibleForFreeTrial(customerId)
  const freeTrial = await getFreeTrial()

--- a/backend/src/services/session-timer.service.js
+++ b/backend/src/services/session-timer.service.js
@@ -1,6 +1,7 @@
 import { getDb } from '../db/client.js'
 import { publish } from '../plugins/valkey.js'
 import { sendToSessionParticipant } from '../plugins/websocket.js'
+import { UserType, SessionStatus, WsMessage } from '../constants.js'

 const sql = getDb()

@@ -62,34 +63,101 @@ export const extendSessionTimer = async (sessionId, additionalMinutes) => {
 }

 const onSessionWarning = (sessionId) => {
-  const data = { type: 'session_timer', remaining_seconds: 60, session_id: sessionId }
-  sendToSessionParticipant(sessionId, 'customer', data)
-  sendToSessionParticipant(sessionId, 'mitra', data)
+  const data = { type: WsMessage.SESSION_TIMER, remaining_seconds: 60, session_id: sessionId }
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, data)
+  sendToSessionParticipant(sessionId, UserType.MITRA, data)
 }

+// Grace period timers for auto-completing abandoned sessions
+const closureGraceTimers = new Map()
+
+const CLOSURE_GRACE_PERIOD_MS = 5 * 60_000 // 5 minutes
+
 const onSessionExpired = async (sessionId) => {
  clearSessionTimer(sessionId)

-  // Check session is still active
+  // Move session to closing status
  const [session] = await sql`
-    SELECT id, status FROM chat_sessions WHERE id = ${sessionId} AND status = 'active'
+    UPDATE chat_sessions
+    SET status = ${SessionStatus.CLOSING}
+    WHERE id = ${sessionId} AND status = ${SessionStatus.ACTIVE}
+    RETURNING id, customer_id, mitra_id
  `
  if (!session) return

-  // Notify both parties
-  const data = { type: 'session_expired', session_id: sessionId }
-  sendToSessionParticipant(sessionId, 'customer', data)
-  sendToSessionParticipant(sessionId, 'mitra', data)
+  // Notify customer — sees extend/close dialog
+  const expiredData = { type: WsMessage.SESSION_EXPIRED, session_id: sessionId }
+  sendToSessionParticipant(sessionId, UserType.CUSTOMER, expiredData)
+
+  // Notify mitra — sees expired + closing (waits for customer's decision or goodbye)
+  sendToSessionParticipant(sessionId, UserType.MITRA, expiredData)
+  sendToSessionParticipant(sessionId, UserType.MITRA, {
+    type: WsMessage.SESSION_CLOSING, session_id: sessionId,
+  })

  // Also publish via Valkey for any listeners
-  await publish(`session:${sessionId}:status`, data)
+  await publish(`session:${sessionId}:status`, expiredData)
+
+  // Start grace period — auto-complete if closing messages aren't submitted
+  const graceTimerId = setTimeout(async () => {
+    closureGraceTimers.delete(sessionId)
+    try {
+      const [stale] = await sql`
+        SELECT id FROM chat_sessions
+        WHERE id = ${sessionId} AND status = ${SessionStatus.CLOSING}
+      `
+      if (stale) {
+        await sql`
+          UPDATE chat_sessions
+          SET status = ${SessionStatus.COMPLETED}, ended_at = NOW(), ended_by = 'system'
+          WHERE id = ${sessionId} AND status = ${SessionStatus.CLOSING}
+        `
+        const data = { type: WsMessage.SESSION_COMPLETED, session_id: sessionId }
+        sendToSessionParticipant(sessionId, UserType.CUSTOMER, data)
+        sendToSessionParticipant(sessionId, UserType.MITRA, data)
+        console.log(`Auto-completed abandoned session ${sessionId} after grace period`)
+      }
+    } catch (_) {}
+  }, CLOSURE_GRACE_PERIOD_MS)
+  closureGraceTimers.set(sessionId, graceTimerId)
+}
+
+export const clearClosureGraceTimer = (sessionId) => {
+  const timerId = closureGraceTimers.get(sessionId)
+  if (timerId) {
+    clearTimeout(timerId)
+    closureGraceTimers.delete(sessionId)
+  }
 }

 // Restore timers for active sessions on server restart
 export const restoreActiveTimers = async () => {
+  // Expire sessions that already passed their expires_at while server was down
+  const staleSessions = await sql`
+    UPDATE chat_sessions
+    SET status = ${SessionStatus.COMPLETED}, ended_at = expires_at, ended_by = 'system'
+    WHERE status = ${SessionStatus.ACTIVE} AND expires_at IS NOT NULL AND expires_at <= NOW()
+    RETURNING id
+  `
+  if (staleSessions.length > 0) {
+    console.log(`Auto-completed ${staleSessions.length} expired session(s)`)
+  }
+
+  // Auto-complete sessions stuck in 'closing' status (abandoned during grace period)
+  const staleClosing = await sql`
+    UPDATE chat_sessions
+    SET status = ${SessionStatus.COMPLETED}, ended_at = NOW(), ended_by = 'system'
+    WHERE status = ${SessionStatus.CLOSING}
+    RETURNING id
+  `
+  if (staleClosing.length > 0) {
+    console.log(`Auto-completed ${staleClosing.length} abandoned closing session(s)`)
+  }
+
+  // Restore timers for sessions still within their time window
  const activeSessions = await sql`
    SELECT id, expires_at FROM chat_sessions
-    WHERE status = 'active' AND expires_at IS NOT NULL AND expires_at > NOW()
+    WHERE status = ${SessionStatus.ACTIVE} AND expires_at IS NOT NULL AND expires_at > NOW()
  `
  for (const session of activeSessions) {
    startSessionTimer(session.id, session.expires_at)
--- a/backend/src/services/session.service.js
+++ b/backend/src/services/session.service.js
@@ -1,5 +1,6 @@
 import { getDb } from '../db/client.js'
 import { publish } from '../plugins/valkey.js'
+import { UserType, SessionStatus, WsMessage } from '../constants.js'

 const sql = getDb()

@@ -11,7 +12,7 @@ export const getActiveSessionByCustomer = async (customerId) => {
    FROM chat_sessions cs
    LEFT JOIN mitras m ON m.id = cs.mitra_id
    WHERE cs.customer_id = ${customerId}
-      AND cs.status IN ('active', 'pending_payment', 'extending', 'closing')
+      AND cs.status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT}, ${SessionStatus.EXTENDING}, ${SessionStatus.CLOSING})
    ORDER BY cs.created_at DESC LIMIT 1
  `
  return session
@@ -25,17 +26,20 @@ export const getActiveSessionsByMitra = async (mitraId) => {
    FROM chat_sessions cs
    INNER JOIN customers c ON c.id = cs.customer_id
    WHERE cs.mitra_id = ${mitraId}
-      AND cs.status IN ('active', 'pending_payment', 'extending', 'closing')
+      AND cs.status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT}, ${SessionStatus.EXTENDING}, ${SessionStatus.CLOSING})
    ORDER BY cs.created_at DESC
  `
  return sessions
 }

-export const endSession = async (sessionId, endedBy) => {
+export const endSession = async (sessionId, endedBy, userId) => {
+  // Validate session belongs to this user
+  const ownerCol = endedBy === UserType.CUSTOMER ? 'customer_id' : 'mitra_id'
  const [session] = await sql`
    UPDATE chat_sessions
-    SET status = 'completed', ended_at = NOW(), ended_by = ${endedBy}
-    WHERE id = ${sessionId} AND status IN ('active', 'pending_payment')
+    SET status = ${SessionStatus.COMPLETED}, ended_at = NOW(), ended_by = ${endedBy}
+    WHERE id = ${sessionId} AND status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})
+      AND ${sql(ownerCol)} = ${userId}
    RETURNING id, customer_id, mitra_id, status, ended_at, ended_by
  `

@@ -47,7 +51,7 @@ export const endSession = async (sessionId, endedBy) => {

  // Notify both parties
  await publish(`session:${sessionId}:status`, {
-    type: 'session_ended',
+    type: WsMessage.SESSION_ENDED,
    session_id: sessionId,
    ended_by: endedBy,
  })
@@ -59,7 +63,7 @@ export const rerouteSession = async (sessionId, newMitraId) => {
  // Get current session
  const [current] = await sql`
    SELECT id, customer_id, mitra_id, status FROM chat_sessions
-    WHERE id = ${sessionId} AND status IN ('active', 'pending_payment')
+    WHERE id = ${sessionId} AND status IN (${SessionStatus.ACTIVE}, ${SessionStatus.PENDING_PAYMENT})
  `

  if (!current) {
@@ -94,7 +98,7 @@ export const rerouteSession = async (sessionId, newMitraId) => {

  // Notify customer about reroute
  await publish(`session:${sessionId}:status`, {
-    type: 'rerouted',
+    type: WsMessage.REROUTED,
    session_id: sessionId,
    mitra_display_name: newMitra.display_name,
  })
@@ -102,14 +106,14 @@ export const rerouteSession = async (sessionId, newMitraId) => {
  // Notify old mitra session removed
  if (oldMitraId) {
    await publish(`mitra:${oldMitraId}:requests`, {
-      type: 'session_rerouted',
+      type: WsMessage.SESSION_REROUTED,
      session_id: sessionId,
    })
  }

  // Notify new mitra about new session
  await publish(`mitra:${newMitraId}:requests`, {
-    type: 'session_assigned',
+    type: WsMessage.SESSION_ASSIGNED,
    session_id: sessionId,
  })

@@ -157,17 +161,17 @@ export const getCustomerHistory = async (customerId, { page = 1, limit = 20 } =
    SELECT cs.id, cs.mitra_id, cs.status, cs.created_at, cs.paired_at, cs.ended_at,
      cs.duration_minutes, cs.price, cs.is_free_trial, cs.extended_minutes,
      m.display_name AS mitra_display_name,
-      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = 'mitra' LIMIT 1) AS mitra_closure_message,
-      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = 'customer' LIMIT 1) AS customer_closure_message
+      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = ${UserType.MITRA} LIMIT 1) AS mitra_closure_message,
+      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = ${UserType.CUSTOMER} LIMIT 1) AS customer_closure_message
    FROM chat_sessions cs
    LEFT JOIN mitras m ON m.id = cs.mitra_id
    WHERE cs.customer_id = ${customerId}
-      AND cs.status = 'completed'
+      AND cs.status = ${SessionStatus.COMPLETED}
    ORDER BY cs.ended_at DESC
    LIMIT ${limit} OFFSET ${offset}
  `
  const [{ count }] = await sql`
-    SELECT COUNT(*) FROM chat_sessions WHERE customer_id = ${customerId} AND status = 'completed'
+    SELECT COUNT(*) FROM chat_sessions WHERE customer_id = ${customerId} AND status = ${SessionStatus.COMPLETED}
  `
  return { items, total: Number(count), page, limit }
 }
@@ -178,17 +182,17 @@ export const getMitraHistory = async (mitraId, { page = 1, limit = 20 } = {}) =>
    SELECT cs.id, cs.customer_id, cs.status, cs.created_at, cs.paired_at, cs.ended_at,
      cs.duration_minutes, cs.price, cs.is_free_trial, cs.extended_minutes,
      c.display_name AS customer_display_name,
-      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = 'mitra' LIMIT 1) AS mitra_closure_message,
-      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = 'customer' LIMIT 1) AS customer_closure_message
+      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = ${UserType.MITRA} LIMIT 1) AS mitra_closure_message,
+      (SELECT message FROM session_closures WHERE session_id = cs.id AND user_type = ${UserType.CUSTOMER} LIMIT 1) AS customer_closure_message
    FROM chat_sessions cs
    INNER JOIN customers c ON c.id = cs.customer_id
    WHERE cs.mitra_id = ${mitraId}
-      AND cs.status = 'completed'
+      AND cs.status = ${SessionStatus.COMPLETED}
    ORDER BY cs.ended_at DESC
    LIMIT ${limit} OFFSET ${offset}
  `
  const [{ count }] = await sql`
-    SELECT COUNT(*) FROM chat_sessions WHERE mitra_id = ${mitraId} AND status = 'completed'
+    SELECT COUNT(*) FROM chat_sessions WHERE mitra_id = ${mitraId} AND status = ${SessionStatus.COMPLETED}
  `
  return { items, total: Number(count), page, limit }
 }
--- a/client_app/android/app/build.gradle.kts
+++ b/client_app/android/app/build.gradle.kts
@@ -14,6 +14,7 @@ android {
    ndkVersion = flutter.ndkVersion

    compileOptions {
+        isCoreLibraryDesugaringEnabled = true
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
    }
@@ -42,6 +43,10 @@ android {
    }
 }

+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")
+}
+
 flutter {
    source = "../.."
 }
--- a/client_app/lib/core/api/api_client.dart
+++ b/client_app/lib/core/api/api_client.dart
@@ -32,8 +32,4 @@ class ApiClient {
    final response = await _dio.get(path, queryParameters: queryParameters);
    return response.data as Map<String, dynamic>;
  }
-
-  Future<Response> getStream(String path) async {
-    return _dio.get(path, options: Options(responseType: ResponseType.stream));
-  }
 }
--- a/client_app/lib/core/auth/auth_bloc.dart
+++ b/client_app/lib/core/auth/auth_bloc.dart
@@ -76,7 +76,7 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
  final _auth = FirebaseAuth.instance;
  String? _pendingVerificationId;

-  AuthBloc({required this.apiClient}) : super(AuthInitial()) {
+  AuthBloc({required this.apiClient}) : super(AuthLoading()) {
    on<AppStarted>(_onAppStarted);
    on<AnonymousLoginRequested>(_onAnonymousLogin);
    on<GoogleLoginRequested>(_onGoogleLogin);
--- a/client_app/lib/core/chat/chat_bloc.dart
+++ b/client_app/lib/core/chat/chat_bloc.dart
@@ -5,6 +5,7 @@ import 'package:firebase_auth/firebase_auth.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:web_socket_channel/web_socket_channel.dart';
 import '../api/api_client.dart';
+import '../constants.dart';

 // Events
 abstract class ChatEvent extends Equatable {
@@ -125,8 +126,8 @@ class ChatMessage {
    required this.id,
    required this.senderType,
    required this.content,
-    this.type = 'text',
-    this.status = 'sent',
+    this.type = MessageType.text,
+    this.status = MessageStatus.sent,
    required this.createdAt,
  });

@@ -164,6 +165,19 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
    emit(ChatConnecting());

    try {
+      // Check session status before connecting
+      final sessionInfo = await apiClient.get('/api/shared/chat/${event.sessionId}/info');
+      final sessionData = sessionInfo['data'] as Map<String, dynamic>?;
+      final sessionStatus = sessionData?['status'] as String?;
+      if (sessionStatus == SessionStatus.completed ||
+          sessionStatus == SessionStatus.cancelled ||
+          sessionStatus == SessionStatus.expired) {
+        emit(ChatError('Sesi sudah berakhir.'));
+        return;
+      }
+
+      final isClosing = sessionStatus == SessionStatus.closing;
+
      // Load existing messages from API
      final response = await apiClient.get(
        '/api/shared/chat/${event.sessionId}/messages',
@@ -173,8 +187,8 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
        id: m['id'] as String,
        senderType: m['sender_type'] as String,
        content: m['content'] as String,
-        type: m['type'] as String? ?? 'text',
-        status: m['status'] as String? ?? 'sent',
+        type: m['type'] as String? ?? MessageType.text,
+        status: m['status'] as String? ?? MessageStatus.sent,
        createdAt: DateTime.parse(m['created_at'] as String),
      )).toList();

@@ -197,12 +211,15 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {

      // Send auth message
      _channel!.sink.add(jsonEncode({
-        'type': 'auth',
+        'type': WsMessage.auth,
        'token': token,
        'session_id': event.sessionId,
      }));

-      emit(ChatConnected(messages: messages));
+      emit(ChatConnected(
+        messages: messages,
+        sessionClosing: isClosing,
+      ));
    } catch (e) {
      emit(ChatError('Gagal terhubung ke chat.'));
    }
@@ -221,7 +238,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
    final tempId = 'temp_${DateTime.now().millisecondsSinceEpoch}';
    final msg = ChatMessage(
      id: tempId,
-      senderType: 'customer',
+      senderType: UserType.customer,
      content: event.content,
      status: 'sending',
      createdAt: DateTime.now(),
@@ -230,7 +247,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
    emit(current.copyWith(messages: [...current.messages, msg]));

    _channel!.sink.add(jsonEncode({
-      'type': 'message',
+      'type': WsMessage.message,
      'content': event.content,
      '_temp_id': tempId,
    }));
@@ -238,13 +255,13 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {

  void _onSendTyping(SendTyping event, Emitter<ChatState> emit) {
    if (_channel == null) return;
-    _channel!.sink.add(jsonEncode({'type': 'typing'}));
+    _channel!.sink.add(jsonEncode({'type': WsMessage.typing}));
  }

  void _onMarkDelivered(MarkMessagesDelivered event, Emitter<ChatState> emit) {
    if (_channel == null) return;
    _channel!.sink.add(jsonEncode({
-      'type': 'delivered',
+      'type': WsMessage.delivered,
      'message_ids': event.messageIds,
    }));
  }
@@ -252,7 +269,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
  void _onMarkRead(MarkMessagesRead event, Emitter<ChatState> emit) {
    if (_channel == null) return;
    _channel!.sink.add(jsonEncode({
-      'type': 'read',
+      'type': WsMessage.read,
      'message_ids': event.messageIds,
    }));
  }
@@ -264,17 +281,17 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
    final type = data['type'] as String?;

    switch (type) {
-      case 'auth_ok':
+      case WsMessage.authOk:
        // Already connected
        break;

-      case 'message':
+      case WsMessage.message:
        final msg = ChatMessage(
          id: data['message_id'] as String,
          senderType: data['sender_type'] as String,
          content: data['content'] as String,
-          type: data['message_type'] as String? ?? 'text',
-          status: 'sent',
+          type: data['message_type'] as String? ?? MessageType.text,
+          status: MessageStatus.sent,
          createdAt: DateTime.parse(data['created_at'] as String),
        );
        emit(current.copyWith(messages: [...current.messages, msg]));
@@ -282,7 +299,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
        add(MarkMessagesDelivered([msg.id]));
        break;

-      case 'message_ack':
+      case WsMessage.messageAck:
        final messageId = data['message_id'] as String;
        final status = data['status'] as String;
        final updatedMessages = current.messages.map((m) {
@@ -292,7 +309,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
          return m;
        }).toList();
        // Replace temp ID with real ID
-        final idx = updatedMessages.indexWhere((m) => m.status == status && m.senderType == 'customer');
+        final idx = updatedMessages.indexWhere((m) => m.status == status && m.senderType == UserType.customer);
        if (idx >= 0) {
          final old = updatedMessages[idx];
          updatedMessages[idx] = ChatMessage(
@@ -307,7 +324,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
        emit(current.copyWith(messages: updatedMessages));
        break;

-      case 'message_status':
+      case WsMessage.messageStatus:
        final messageIds = (data['message_ids'] as List<dynamic>).cast<String>();
        final status = data['status'] as String;
        final updatedMessages = current.messages.map((m) {
@@ -319,7 +336,7 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
        emit(current.copyWith(messages: updatedMessages));
        break;

-      case 'typing':
+      case WsMessage.typing:
        emit(current.copyWith(isOtherTyping: true));
        _typingTimer?.cancel();
        _typingTimer = Timer(const Duration(seconds: 3), () {
@@ -329,36 +346,41 @@ class ChatBloc extends Bloc<ChatEvent, ChatState> {
        });
        break;

-      case 'session_timer':
+      case WsMessage.sessionTimer:
        final remaining = data['remaining_seconds'] as int?;
        emit(current.copyWith(remainingSeconds: remaining));
        break;

-      case 'session_expired':
+      case WsMessage.sessionExpired:
        emit(current.copyWith(sessionExpired: true));
        break;

-      case 'session_paused':
+      case WsMessage.sessionPaused:
        emit(current.copyWith(sessionPaused: true));
        break;

-      case 'session_resumed':
-        emit(current.copyWith(sessionPaused: false, sessionExpired: false));
+      case WsMessage.sessionResumed:
+        emit(current.copyWith(sessionPaused: false, sessionExpired: false, sessionClosing: false));
        break;

-      case 'session_closing':
+      case WsMessage.sessionClosing:
        emit(current.copyWith(sessionClosing: true));
        break;

-      case 'extension_response':
-        emit(current.copyWith(extensionResponse: data));
+      case WsMessage.extensionResponse:
+        final accepted = data['accepted'] as bool? ?? false;
+        emit(current.copyWith(
+          extensionResponse: data,
+          sessionPaused: accepted ? false : current.sessionPaused,
+          sessionExpired: accepted ? false : current.sessionExpired,
+        ));
        break;

-      case 'session_completed':
+      case WsMessage.sessionCompleted:
        _cleanup();
        break;

-      case 'error':
+      case WsMessage.error:
        // Keep connected but show error
        break;
    }
--- a/client_app/lib/core/chat/session_closure_bloc.dart
+++ b/client_app/lib/core/chat/session_closure_bloc.dart
@@ -18,6 +18,7 @@ class RequestExtension extends SessionClosureEvent {
 }

 class DeclineExtension extends SessionClosureEvent {}
+class ResetClosure extends SessionClosureEvent {}

 class SubmitGoodbye extends SessionClosureEvent {
  final String sessionId;
@@ -56,6 +57,7 @@ class SessionClosureBloc extends Bloc<SessionClosureEvent, SessionClosureState>
  SessionClosureBloc({required this.apiClient}) : super(ClosureInitial()) {
    on<RequestExtension>(_onRequestExtension);
    on<DeclineExtension>(_onDeclineExtension);
+    on<ResetClosure>(_onReset);
    on<SubmitGoodbye>(_onSubmitGoodbye);
  }

@@ -76,6 +78,10 @@ class SessionClosureBloc extends Bloc<SessionClosureEvent, SessionClosureState>
    emit(ClosureShowGoodbye());
  }

+  void _onReset(ResetClosure event, Emitter<SessionClosureState> emit) {
+    emit(ClosureInitial());
+  }
+
  Future<void> _onSubmitGoodbye(SubmitGoodbye event, Emitter<SessionClosureState> emit) async {
    emit(ClosureSubmitting());
    try {
--- a/client_app/lib/core/constants.dart
+++ b/client_app/lib/core/constants.dart
@@ -0,0 +1,83 @@
+/// User types
+class UserType {
+  static const customer = 'customer';
+  static const mitra = 'mitra';
+  UserType._();
+}
+
+/// Chat session statuses
+class SessionStatus {
+  static const searching = 'searching';
+  static const pendingAcceptance = 'pending_acceptance';
+  static const pendingPayment = 'pending_payment';
+  static const active = 'active';
+  static const extending = 'extending';
+  static const closing = 'closing';
+  static const completed = 'completed';
+  static const cancelled = 'cancelled';
+  static const expired = 'expired';
+  SessionStatus._();
+}
+
+/// Chat message statuses
+class MessageStatus {
+  static const sent = 'sent';
+  static const delivered = 'delivered';
+  static const read = 'read';
+  MessageStatus._();
+}
+
+/// Chat message types
+class MessageType {
+  static const text = 'text';
+  MessageType._();
+}
+
+/// Session extension statuses
+class ExtensionStatus {
+  static const pending = 'pending';
+  static const accepted = 'accepted';
+  static const rejected = 'rejected';
+  static const timeout = 'timeout';
+  ExtensionStatus._();
+}
+
+/// WebSocket message types
+class WsMessage {
+  // Auth
+  static const auth = 'auth';
+  static const authOk = 'auth_ok';
+  static const error = 'error';
+
+  // Chat
+  static const message = 'message';
+  static const messageAck = 'message_ack';
+  static const messageStatus = 'message_status';
+  static const typing = 'typing';
+
+  // Pairing
+  static const chatRequest = 'chat_request';
+  static const chatRequestClosed = 'chat_request_closed';
+  static const paired = 'paired';
+
+  // Session lifecycle
+  static const sessionTimer = 'session_timer';
+  static const sessionExpired = 'session_expired';
+  static const sessionClosing = 'session_closing';
+  static const sessionCompleted = 'session_completed';
+  static const sessionPaused = 'session_paused';
+  static const sessionResumed = 'session_resumed';
+
+  // Extension
+  static const extensionRequest = 'extension_request';
+  static const extensionResponse = 'extension_response';
+
+  // Delivery
+  static const delivered = 'delivered';
+  static const read = 'read';
+
+  // Early end
+  static const earlyEnd = 'early_end';
+
+  WsMessage._();
+}
--- a/client_app/lib/core/notifications/notification_service.dart
+++ b/client_app/lib/core/notifications/notification_service.dart
@@ -0,0 +1,95 @@
+import 'dart:convert';
+import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+import 'package:go_router/go_router.dart';
+
+/// Handles FCM foreground/background notifications and local notification display.
+class NotificationService {
+  static final _localNotifications = FlutterLocalNotificationsPlugin();
+  static GoRouter? _router;
+
+  static const _channel = AndroidNotificationChannel(
+    'chat_messages',
+    'Chat Messages',
+    description: 'Notifications for incoming chat messages',
+    importance: Importance.high,
+  );
+
+  static Future<void> initialize(GoRouter router) async {
+    _router = router;
+
+    // Create Android notification channel
+    await _localNotifications
+        .resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()
+        ?.createNotificationChannel(_channel);
+
+    // Initialize local notifications
+    await _localNotifications.initialize(
+      settings: const InitializationSettings(
+        android: AndroidInitializationSettings('@mipmap/ic_launcher'),
+        iOS: DarwinInitializationSettings(),
+      ),
+      onDidReceiveNotificationResponse: _onNotificationTap,
+    );
+
+    // FCM foreground messages → show local notification
+    FirebaseMessaging.onMessage.listen(_onForegroundMessage);
+
+    // FCM notification tap (app was in background)
+    FirebaseMessaging.onMessageOpenedApp.listen(_onMessageOpenedApp);
+
+    // Check if app was opened from a terminated state via notification
+    final initialMessage = await FirebaseMessaging.instance.getInitialMessage();
+    if (initialMessage != null) {
+      _navigateFromMessage(initialMessage.data);
+    }
+  }
+
+  static void _onForegroundMessage(RemoteMessage message) {
+    final notification = message.notification;
+    if (notification == null) return;
+
+    _localNotifications.show(
+      id: notification.hashCode,
+      title: notification.title,
+      body: notification.body,
+      notificationDetails: NotificationDetails(
+        android: AndroidNotificationDetails(
+          _channel.id,
+          _channel.name,
+          channelDescription: _channel.description,
+          importance: Importance.high,
+          priority: Priority.high,
+        ),
+        iOS: const DarwinNotificationDetails(
+          presentAlert: true,
+          presentBadge: true,
+          presentSound: true,
+        ),
+      ),
+      payload: jsonEncode(message.data),
+    );
+  }
+
+  static void _onNotificationTap(NotificationResponse response) {
+    if (response.payload == null) return;
+    try {
+      final data = jsonDecode(response.payload!) as Map<String, dynamic>;
+      _navigateFromMessage(data);
+    } catch (_) {}
+  }
+
+  static void _onMessageOpenedApp(RemoteMessage message) {
+    _navigateFromMessage(message.data);
+  }
+
+  static void _navigateFromMessage(Map<String, dynamic> data) {
+    final sessionId = data['session_id'] as String?;
+    if (sessionId == null || _router == null) return;
+
+    final type = data['type'] as String?;
+    if (type == 'chat_message' || type == 'chat_request') {
+      _router!.push('/chat/session/$sessionId');
+    }
+  }
+}
--- a/client_app/lib/core/pairing/pairing_bloc.dart
+++ b/client_app/lib/core/pairing/pairing_bloc.dart
@@ -2,8 +2,11 @@ import 'dart:async';
 import 'dart:convert';
 import 'package:dio/dio.dart';
 import 'package:equatable/equatable.dart';
+import 'package:firebase_auth/firebase_auth.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:web_socket_channel/web_socket_channel.dart';
 import '../api/api_client.dart';
+import '../constants.dart';

 // Events
 abstract class PairingEvent extends Equatable {
@@ -32,6 +35,7 @@ class _PairingStatusUpdate extends PairingEvent {
 }

 class _PairingTimeout extends PairingEvent {}
+class _ConnectionError extends PairingEvent {}

 // States
 abstract class PairingState extends Equatable {
@@ -77,7 +81,8 @@ class PairingError extends PairingState {
 class PairingBloc extends Bloc<PairingEvent, PairingState> {
  final ApiClient apiClient;
  Timer? _timeoutTimer;
-  StreamSubscription? _sseSubscription;
+  WebSocketChannel? _channel;
+  StreamSubscription? _wsSubscription;

  PairingBloc({required this.apiClient}) : super(PairingInitial()) {
    on<RequestPairing>(_onRequestPairing);
@@ -85,6 +90,7 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
    on<CancelPairing>(_onCancelPairing);
    on<_PairingStatusUpdate>(_onStatusUpdate);
    on<_PairingTimeout>(_onTimeout);
+    on<_ConnectionError>(_onConnectionError);
  }

  Future<void> _onRequestPairing(RequestPairing event, Emitter<PairingState> emit) async {
@@ -107,6 +113,9 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
      emit(PairingInitial());
    }
    try {
+      // Connect to WebSocket first to listen for pairing status
+      await _connectWebSocket();
+
      final response = await apiClient.post('/api/client/chat/request', data: body);
      final data = response['data'] as Map<String, dynamic>;
      final sessionId = data['id'] as String;
@@ -116,9 +125,8 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
      _timeoutTimer = Timer(const Duration(seconds: 60), () {
        add(_PairingTimeout());
      });
-
-      _listenToSSE(sessionId);
    } on DioException catch (e) {
+      _cleanup();
      final code = e.response?.data?['error']?['code'];
      if (code == 'NO_MITRA_AVAILABLE') {
        emit(PairingNoBestie());
@@ -132,26 +140,45 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
    }
  }

-  void _listenToSSE(String sessionId) {
-    apiClient.getStream('/api/client/chat/request/$sessionId/status').then((response) {
-      final stream = response.data.stream as Stream<List<int>>;
-      _sseSubscription = stream
-          .transform(utf8.decoder)
-          .transform(const LineSplitter())
-          .where((line) => line.startsWith('data: '))
-          .map((line) => jsonDecode(line.substring(6)) as Map<String, dynamic>)
-          .listen(
-            (data) => add(_PairingStatusUpdate(data)),
-            onError: (_) {},
+  Future<void> _connectWebSocket() async {
+    _closeWebSocket();
+    final user = FirebaseAuth.instance.currentUser;
+    if (user == null) return;
+
+    final token = await user.getIdToken();
+    final wsUrl = ApiClient.baseUrl
+        .replaceFirst('https://', 'wss://')
+        .replaceFirst('http://', 'ws://');
+
+    _channel = WebSocketChannel.connect(Uri.parse('$wsUrl/api/shared/ws'));
+
+    _wsSubscription = _channel!.stream.listen(
+      (raw) {
+        final data = jsonDecode(raw as String) as Map<String, dynamic>;
+        if (data['type'] == WsMessage.authOk) return;
+        add(_PairingStatusUpdate(data));
+      },
+      onError: (_) => add(_ConnectionError()),
+      onDone: () => add(_ConnectionError()),
    );
-    }).catchError((_) {});
+
+    // Authenticate without session_id — just for receiving pairing status
+    _channel!.sink.add(jsonEncode({
+      'type': WsMessage.auth,
+      'token': token,
+    }));
+  }
+
+  Future<void> _onConnectionError(_ConnectionError event, Emitter<PairingState> emit) async {
+    // WebSocket disconnected during pairing — stay in current state,
+    // FCM will still deliver notifications
  }

  Future<void> _onStatusUpdate(_PairingStatusUpdate event, Emitter<PairingState> emit) async {
    final data = event.data;
    final type = data['type'] as String?;

-    if (type == 'paired') {
+    if (type == WsMessage.paired) {
      _cleanup();
      final mitraName = data['mitra_display_name'] as String? ?? 'Bestie';
      final sessionId = data['session_id'] as String;
@@ -160,7 +187,7 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
      // Brief delay then transition to active
      await Future.delayed(const Duration(seconds: 2));
      emit(PairingActive(sessionId: sessionId, mitraName: mitraName));
-    } else if (type == 'expired') {
+    } else if (type == SessionStatus.expired) {
      _cleanup();
      emit(PairingNoBestie());
    }
@@ -182,11 +209,17 @@ class PairingBloc extends Bloc<PairingEvent, PairingState> {
    emit(PairingNoBestie());
  }

+  void _closeWebSocket() {
+    _wsSubscription?.cancel();
+    _wsSubscription = null;
+    _channel?.sink.close();
+    _channel = null;
+  }
+
  void _cleanup() {
    _timeoutTimer?.cancel();
    _timeoutTimer = null;
-    _sseSubscription?.cancel();
-    _sseSubscription = null;
+    _closeWebSocket();
  }

  @override
--- a/client_app/lib/features/chat/screens/chat_screen.dart
+++ b/client_app/lib/features/chat/screens/chat_screen.dart
@@ -4,6 +4,7 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:go_router/go_router.dart';
 import '../../../core/chat/chat_bloc.dart';
 import '../../../core/chat/session_closure_bloc.dart';
+import '../../../core/constants.dart';
 import '../widgets/pricing_bottom_sheet.dart';

 class ChatScreen extends StatefulWidget {
@@ -21,8 +22,15 @@ class _ChatScreenState extends State<ChatScreen> {
  final _scrollController = ScrollController();
  Timer? _typingThrottle;

+  @override
+  void initState() {
+    super.initState();
+    context.read<ChatBloc>().add(ConnectChat(widget.sessionId));
+  }
+
  @override
  void dispose() {
+    context.read<ChatBloc>().add(DisconnectChat());
    _messageController.dispose();
    _scrollController.dispose();
    _typingThrottle?.cancel();
@@ -64,19 +72,31 @@ class _ChatScreenState extends State<ChatScreen> {
            if (prev is ChatConnected && curr is ChatConnected) {
              return prev.sessionExpired != curr.sessionExpired ||
                  prev.sessionClosing != curr.sessionClosing ||
+                  prev.sessionPaused != curr.sessionPaused ||
                  prev.messages.length != curr.messages.length;
            }
            return true;
          },
          listener: (context, state) {
            if (state is ChatConnected) {
-              if (state.sessionClosing) {
+              // Only trigger goodbye if closing AND not expired (expired shows extend dialog first)
+              if (state.sessionClosing && !state.sessionExpired) {
+                final closureState = context.read<SessionClosureBloc>().state;
+                if (closureState is ClosureInitial) {
                  context.read<SessionClosureBloc>().add(DeclineExtension());
                }
+              }
+              // Extension accepted — reset closure bloc to go back to chat
+              if (!state.sessionPaused && !state.sessionExpired && !state.sessionClosing) {
+                final closureState = context.read<SessionClosureBloc>().state;
+                if (closureState is! ClosureInitial) {
+                  context.read<SessionClosureBloc>().add(ResetClosure());
+                }
+              }
              _scrollToBottom();
              // Auto-mark received messages as read
              final unread = state.messages
-                  .where((m) => m.senderType == 'mitra' && m.status != 'read')
+                  .where((m) => m.senderType == UserType.mitra && m.status != MessageStatus.read)
                  .map((m) => m.id)
                  .toList();
              if (unread.isNotEmpty) {
@@ -138,17 +158,17 @@ class _ChatScreenState extends State<ChatScreen> {
  }

  Widget _buildChatBody(BuildContext context, ChatConnected state) {
-    // Show session expired dialog
-    if (state.sessionExpired) {
-      return _buildExpiredView(context);
-    }
-
-    // Show goodbye input
+    // Show goodbye input (takes priority — user already decided to close)
    final closureState = context.watch<SessionClosureBloc>().state;
    if (closureState is ClosureShowGoodbye || closureState is ClosureSubmitting) {
      return _buildGoodbyeView(context, closureState);
    }

+    // Show session expired dialog (extend or close?)
+    if (state.sessionExpired) {
+      return _buildExpiredView(context);
+    }
+
    if (state.sessionPaused) {
      return _buildPausedView();
    }
@@ -162,7 +182,7 @@ class _ChatScreenState extends State<ChatScreen> {
            itemCount: state.messages.length,
            itemBuilder: (context, index) {
              final msg = state.messages[index];
-              final isMe = msg.senderType == 'customer';
+              final isMe = msg.senderType == UserType.customer;
              return _buildMessageBubble(msg, isMe);
            },
          ),
@@ -219,11 +239,11 @@ class _ChatScreenState extends State<ChatScreen> {
    switch (status) {
      case 'sending':
        return const Icon(Icons.access_time, size: 14, color: Colors.grey);
-      case 'sent':
+      case MessageStatus.sent:
        return const Icon(Icons.check, size: 14, color: Colors.grey);
-      case 'delivered':
+      case MessageStatus.delivered:
        return const Icon(Icons.done_all, size: 14, color: Colors.grey);
-      case 'read':
+      case MessageStatus.read:
        return const Icon(Icons.done_all, size: 14, color: Colors.blue);
      default:
        return const SizedBox.shrink();
@@ -264,7 +284,19 @@ class _ChatScreenState extends State<ChatScreen> {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
-        child: Column(
+        child: TweenAnimationBuilder<int>(
+          tween: IntTween(begin: 300, end: 0),
+          duration: const Duration(seconds: 300),
+          builder: (context, remaining, _) {
+            if (remaining <= 0) {
+              // Auto-decline when countdown reaches 0
+              WidgetsBinding.instance.addPostFrameCallback((_) {
+                context.read<SessionClosureBloc>().add(DeclineExtension());
+              });
+            }
+            final minutes = remaining ~/ 60;
+            final seconds = remaining % 60;
+            return Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                const Icon(Icons.timer_off, size: 64, color: Colors.orange),
@@ -272,9 +304,18 @@ class _ChatScreenState extends State<ChatScreen> {
                const Text('Waktu sesi habis', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
                const SizedBox(height: 8),
                const Text('Apakah kamu ingin memperpanjang sesi?', textAlign: TextAlign.center),
+                const SizedBox(height: 12),
+                Text(
+                  '$minutes:${seconds.toString().padLeft(2, '0')}',
+                  style: TextStyle(
+                    fontSize: 32,
+                    fontWeight: FontWeight.bold,
+                    color: remaining < 60 ? Colors.red : Colors.orange,
+                  ),
+                ),
                const SizedBox(height: 24),
                ElevatedButton(
-              onPressed: () => PricingBottomSheet.show(context),
+                  onPressed: () => PricingBottomSheet.showForExtension(context, sessionId: widget.sessionId),
                  child: const Text('Perpanjang Sesi'),
                ),
                const SizedBox(height: 12),
@@ -283,6 +324,8 @@ class _ChatScreenState extends State<ChatScreen> {
                  child: const Text('Tidak, akhiri sesi'),
                ),
              ],
+            );
+          },
        ),
      ),
    );
@@ -290,12 +333,11 @@ class _ChatScreenState extends State<ChatScreen> {

  Widget _buildGoodbyeView(BuildContext context, SessionClosureState closureState) {
    final controller = TextEditingController();
-    return Center(
-      child: Padding(
+    return SingleChildScrollView(
      padding: const EdgeInsets.all(32),
      child: Column(
-          mainAxisAlignment: MainAxisAlignment.center,
        children: [
+          const SizedBox(height: 48),
          const Icon(Icons.waving_hand, size: 64, color: Colors.amber),
            const SizedBox(height: 16),
            const Text('Pesan Penutup', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
@@ -328,7 +370,6 @@ class _ChatScreenState extends State<ChatScreen> {
            ),
          ],
        ),
-      ),
    );
  }

--- a/client_app/lib/features/chat/screens/chat_transcript_screen.dart
+++ b/client_app/lib/features/chat/screens/chat_transcript_screen.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../../core/api/api_client.dart';
+import '../../../core/constants.dart';

 class ChatTranscriptScreen extends StatefulWidget {
  final String sessionId;
@@ -47,7 +48,7 @@ class _ChatTranscriptScreenState extends State<ChatTranscriptScreen> {
              padding: const EdgeInsets.all(16),
              children: [
                ..._messages.map((m) {
-                  final isMe = m['sender_type'] == 'customer';
+                  final isMe = m['sender_type'] == UserType.customer;
                  final time = DateTime.parse(m['created_at'] as String).toLocal();
                  return Align(
                    alignment: isMe ? Alignment.centerRight : Alignment.centerLeft,
@@ -79,7 +80,7 @@ class _ChatTranscriptScreenState extends State<ChatTranscriptScreen> {
                  const SizedBox(height: 8),
                  ..._closures.map((c) => Card(
                    child: ListTile(
-                      title: Text(c['user_type'] == 'customer' ? 'Kamu' : 'Bestie'),
+                      title: Text(c['user_type'] == UserType.customer ? 'Kamu' : 'Bestie'),
                      subtitle: Text(c['message'] as String),
                    ),
                  )),
--- a/client_app/lib/features/chat/widgets/pricing_bottom_sheet.dart
+++ b/client_app/lib/features/chat/widgets/pricing_bottom_sheet.dart
@@ -2,19 +2,46 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../../core/api/api_client.dart';
 import '../../../core/chat/chat_opening_bloc.dart';
+import '../../../core/chat/session_closure_bloc.dart';
 import '../../../core/pairing/pairing_bloc.dart';

 class PricingBottomSheet extends StatelessWidget {
-  const PricingBottomSheet({super.key});
+  /// If set, the bottom sheet is in "extension" mode — selecting a tier extends the session.
+  final String? extensionSessionId;

+  const PricingBottomSheet({super.key, this.extensionSessionId});
+
+  /// Show for new pairing (from home screen)
  static Future<void> show(BuildContext context) {
    return showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      builder: (_) => BlocProvider(
        create: (ctx) => ChatOpeningBloc(apiClient: ctx.read<ApiClient>())..add(LoadPricing()),
+        child: MultiBlocProvider(
+          providers: [
+            BlocProvider.value(value: context.read<PairingBloc>()),
+          ],
          child: const PricingBottomSheet(),
        ),
+      ),
+    );
+  }
+
+  /// Show for session extension (from chat screen)
+  static Future<void> showForExtension(BuildContext context, {required String sessionId}) {
+    return showModalBottomSheet(
+      context: context,
+      isScrollControlled: true,
+      builder: (_) => BlocProvider(
+        create: (ctx) => ChatOpeningBloc(apiClient: ctx.read<ApiClient>())..add(LoadPricing()),
+        child: MultiBlocProvider(
+          providers: [
+            BlocProvider.value(value: context.read<SessionClosureBloc>()),
+          ],
+          child: PricingBottomSheet(extensionSessionId: sessionId),
+        ),
+      ),
    );
  }

@@ -30,6 +57,8 @@ class PricingBottomSheet extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
+    final isExtension = extensionSessionId != null;
+
    return BlocBuilder<ChatOpeningBloc, ChatOpeningState>(
      builder: (context, state) {
        if (state is PricingLoading || state is PricingInitial) {
@@ -58,13 +87,13 @@ class PricingBottomSheet extends StatelessWidget {
                child: ListView(
                  controller: scrollController,
                  children: [
-                    const Text(
-                      'Pilih Durasi Curhat',
-                      style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
+                    Text(
+                      isExtension ? 'Perpanjang Durasi' : 'Pilih Durasi Curhat',
+                      style: const TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
                      textAlign: TextAlign.center,
                    ),
                    const SizedBox(height: 16),
-                    if (state.freeTrialEligible) ...[
+                    if (!isExtension && state.freeTrialEligible) ...[
                      Card(
                        color: Colors.green.shade50,
                        child: ListTile(
@@ -89,11 +118,20 @@ class PricingBottomSheet extends StatelessWidget {
                        ),
                        onTap: () {
                          Navigator.of(context).pop();
+                          if (isExtension) {
+                            _requestExtension(
+                              context,
+                              sessionId: extensionSessionId!,
+                              durationMinutes: tier.durationMinutes,
+                              price: tier.price,
+                            );
+                          } else {
                            _startPairing(
                              context,
                              durationMinutes: tier.durationMinutes,
                              price: tier.price,
                            );
+                          }
                        },
                      ),
                    )),
@@ -116,4 +154,12 @@ class PricingBottomSheet extends StatelessWidget {
      isFreeTrial: isFreeTrial,
    ));
  }
+
+  void _requestExtension(BuildContext context, {required String sessionId, required int durationMinutes, required int price}) {
+    context.read<SessionClosureBloc>().add(RequestExtension(
+      sessionId: sessionId,
+      durationMinutes: durationMinutes,
+      price: price,
+    ));
+  }
 }
--- a/client_app/lib/features/home/home_screen.dart
+++ b/client_app/lib/features/home/home_screen.dart
@@ -2,12 +2,64 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:go_router/go_router.dart';
 import '../../core/auth/auth_bloc.dart';
+import '../../core/api/api_client.dart';
 import '../../core/pairing/pairing_bloc.dart';
 import '../chat/widgets/pricing_bottom_sheet.dart';

-class HomeScreen extends StatelessWidget {
+class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

+  @override
+  State<HomeScreen> createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
+  Map<String, dynamic>? _activeSession;
+  bool _loadingSession = true;
+
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+    _checkActiveSession();
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.resumed) {
+      _checkActiveSession();
+    }
+  }
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    // Re-check when navigating back to this screen
+    _checkActiveSession();
+  }
+
+  Future<void> _checkActiveSession() async {
+    try {
+      final apiClient = context.read<ApiClient>();
+      final response = await apiClient.get('/api/client/chat/session/active');
+      final data = response['data'];
+      if (mounted) {
+        setState(() {
+          _activeSession = data is Map<String, dynamic> ? data : null;
+          _loadingSession = false;
+        });
+      }
+    } catch (_) {
+      if (mounted) setState(() => _loadingSession = false);
+    }
+  }
+
  @override
  Widget build(BuildContext context) {
    return BlocListener<PairingBloc, PairingState>(
@@ -51,7 +103,20 @@ class HomeScreen extends StatelessWidget {
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Text('Halo, $displayName!', style: const TextStyle(fontSize: 24)),
-                    const SizedBox(height: 48),
+                    const SizedBox(height: 32),
+                    if (_loadingSession)
+                      const CircularProgressIndicator()
+                    else if (_activeSession != null)
+                      _ActiveSessionCard(
+                        session: _activeSession!,
+                        onTap: () {
+                          final sessionId = _activeSession!['id'] as String;
+                          final mitraName = _activeSession!['mitra_display_name'] as String? ?? 'Bestie';
+                          context.push('/chat/session/$sessionId', extra: mitraName);
+                        },
+                      )
+                    else ...[
+                      const SizedBox(height: 16),
                      ElevatedButton(
                        style: ElevatedButton.styleFrom(
                          padding: const EdgeInsets.symmetric(horizontal: 48, vertical: 16),
@@ -60,6 +125,7 @@ class HomeScreen extends StatelessWidget {
                        child: const Text('Mulai Curhat', style: TextStyle(fontSize: 18)),
                      ),
                    ],
+                  ],
                ),
              ),
            ),
@@ -69,3 +135,52 @@ class HomeScreen extends StatelessWidget {
    );
  }
 }
+
+class _ActiveSessionCard extends StatelessWidget {
+  final Map<String, dynamic> session;
+  final VoidCallback onTap;
+
+  const _ActiveSessionCard({required this.session, required this.onTap});
+
+  @override
+  Widget build(BuildContext context) {
+    final mitraName = session['mitra_display_name'] as String? ?? 'Bestie';
+
+    return Card(
+      elevation: 2,
+      child: InkWell(
+        onTap: onTap,
+        borderRadius: BorderRadius.circular(12),
+        child: Padding(
+          padding: const EdgeInsets.all(20),
+          child: Row(
+            children: [
+              const CircleAvatar(
+                backgroundColor: Colors.green,
+                child: Icon(Icons.chat, color: Colors.white),
+              ),
+              const SizedBox(width: 16),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    const Text(
+                      'Sesi Aktif',
+                      style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
+                    ),
+                    const SizedBox(height: 4),
+                    Text(
+                      'Sedang curhat dengan $mitraName',
+                      style: const TextStyle(fontSize: 14, color: Colors.grey),
+                    ),
+                  ],
+                ),
+              ),
+              const Icon(Icons.chevron_right),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
--- a/client_app/lib/features/splash/splash_screen.dart
+++ b/client_app/lib/features/splash/splash_screen.dart
@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+
+class SplashScreen extends StatelessWidget {
+  const SplashScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Scaffold(
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(Icons.favorite, size: 80, color: Colors.blue),
+            SizedBox(height: 24),
+            Text(
+              'Halo Bestie',
+              style: TextStyle(fontSize: 28, fontWeight: FontWeight.bold),
+            ),
+            SizedBox(height: 32),
+            CircularProgressIndicator(),
+          ],
+        ),
+      ),
+    );
+  }
+}
--- a/client_app/lib/main.dart
+++ b/client_app/lib/main.dart
@@ -8,6 +8,7 @@ import 'core/auth/auth_bloc.dart';
 import 'core/chat/chat_bloc.dart';
 import 'core/chat/session_closure_bloc.dart';
 import 'core/pairing/pairing_bloc.dart';
+import 'core/notifications/notification_service.dart';
 import 'firebase_options.dart';
 import 'router.dart';

@@ -39,6 +40,7 @@ class _AppState extends State<App> {
    super.initState();
    _authBloc = AuthBloc(apiClient: _apiClient)..add(AppStarted());
    _router = buildRouter(_authBloc);
+    NotificationService.initialize(_router);
    _registerFcmToken();
  }

--- a/client_app/lib/router.dart
+++ b/client_app/lib/router.dart
@@ -7,6 +7,7 @@ import 'features/auth/screens/display_name_screen.dart';
 import 'features/auth/screens/register_screen.dart';
 import 'features/auth/screens/otp_screen.dart';
 import 'features/auth/screens/force_register_screen.dart';
+import 'features/splash/splash_screen.dart';
 import 'features/home/home_screen.dart';
 import 'features/chat/screens/searching_screen.dart';
 import 'features/chat/screens/bestie_found_screen.dart';
@@ -32,24 +33,27 @@ class _BlocRefreshNotifier extends ChangeNotifier {

 GoRouter buildRouter(AuthBloc authBloc) {
  return GoRouter(
-    initialLocation: '/welcome',
+    initialLocation: '/splash',
    refreshListenable: _BlocRefreshNotifier(authBloc),
    redirect: (context, state) {
      final authState = authBloc.state;
+      final isSplash = state.matchedLocation == '/splash';
      final isAuthRoute = state.matchedLocation.startsWith('/auth') ||
          state.matchedLocation == '/welcome';

-      // Don't redirect while loading — stay on current screen
-      if (authState is AuthLoading) return null;
+      // Show splash while loading
+      if (authState is AuthLoading) return isSplash ? null : '/splash';

      if (authState is AuthAuthenticated || authState is AuthAnonymous) {
-        return isAuthRoute ? '/home' : null;
+        return (isSplash || isAuthRoute) ? '/home' : null;
      }
      if (authState is AuthForceRegister) return '/auth/force-register';
-      if (!isAuthRoute) return '/welcome';
+      if (!isAuthRoute && !isSplash) return '/welcome';
+      if (isSplash) return '/welcome';
      return null;
    },
    routes: [
+      GoRoute(path: '/splash', builder: (_, __) => const SplashScreen()),
      GoRoute(path: '/welcome', builder: (_, __) => const WelcomeScreen()),
      GoRoute(path: '/auth/display-name', builder: (_, __) => const DisplayNameScreen()),
      GoRoute(path: '/auth/register', builder: (_, __) => const RegisterScreen()),
@@ -66,10 +70,13 @@ GoRouter buildRouter(AuthBloc authBloc) {
      }),
      GoRoute(path: '/chat/no-bestie', builder: (_, __) => const NoBestieScreen()),
      GoRoute(path: '/chat/session/:sessionId', builder: (context, state) {
-        final extra = state.extra as Map<String, dynamic>?;
+        final extra = state.extra;
+        final mitraName = extra is String
+            ? extra
+            : (extra is Map<String, dynamic> ? extra['mitraName'] as String? : null);
        return ChatScreen(
          sessionId: state.pathParameters['sessionId']!,
-          mitraName: extra?['mitraName'] as String? ?? 'Bestie',
+          mitraName: mitraName ?? 'Bestie',
        );
      }),
      GoRoute(path: '/chat/history', builder: (_, __) => const ChatHistoryScreen()),
--- a/client_app/macos/Flutter/GeneratedPluginRegistrant.swift
+++ b/client_app/macos/Flutter/GeneratedPluginRegistrant.swift
@@ -8,6 +8,7 @@ import Foundation
 import firebase_auth
 import firebase_core
 import firebase_messaging
+import flutter_local_notifications
 import google_sign_in_ios
 import shared_preferences_foundation
 import sign_in_with_apple
@@ -16,6 +17,7 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
  FLTFirebaseAuthPlugin.register(with: registry.registrar(forPlugin: "FLTFirebaseAuthPlugin"))
  FLTFirebaseCorePlugin.register(with: registry.registrar(forPlugin: "FLTFirebaseCorePlugin"))
  FLTFirebaseMessagingPlugin.register(with: registry.registrar(forPlugin: "FLTFirebaseMessagingPlugin"))
+  FlutterLocalNotificationsPlugin.register(with: registry.registrar(forPlugin: "FlutterLocalNotificationsPlugin"))
  FLTGoogleSignInPlugin.register(with: registry.registrar(forPlugin: "FLTGoogleSignInPlugin"))
  SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
  SignInWithApplePlugin.register(with: registry.registrar(forPlugin: "SignInWithApplePlugin"))
--- a/client_app/pubspec.lock
+++ b/client_app/pubspec.lock
@@ -9,6 +9,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "1.3.35"
+  args:
+    dependency: transitive
+    description:
+      name: args
+      sha256: d0481093c50b1da8910eb0bb301626d4d8eb7284aa739614d2b394ee09e3ea04
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.7.0"
  async:
    dependency: transitive
    description:
@@ -65,6 +73,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "3.0.7"
+  dbus:
+    dependency: transitive
+    description:
+      name: dbus
+      sha256: d0c98dcd4f5169878b6cf8f6e0a52403a9dff371a3e2f019697accbf6f44a270
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.12"
  dio:
    dependency: "direct main"
    description:
@@ -206,6 +222,38 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "3.0.2"
+  flutter_local_notifications:
+    dependency: "direct main"
+    description:
+      name: flutter_local_notifications
+      sha256: "0d9035862236fe38250fe1644d7ed3b8254e34a21b2c837c9f539fbb3bba5ef1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "21.0.0"
+  flutter_local_notifications_linux:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_linux
+      sha256: e0f25e243c6c44c825bbbc6b2b2e76f7d9222362adcfe9fd780bf01923c840bd
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.0.0"
+  flutter_local_notifications_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_platform_interface
+      sha256: e7db3d5b49c2b7ecc68deba4aaaa67a348f92ee0fef34c8e4b4459dbef0d7307
+      url: "https://pub.dev"
+    source: hosted
+    version: "11.0.0"
+  flutter_local_notifications_windows:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_windows
+      sha256: "3a2654ba104fbb52c618ebed9def24ef270228470718c43b3a6afcd5c81bef0c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.0"
  flutter_test:
    dependency: "direct dev"
    description: flutter
@@ -400,6 +448,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "2.3.0"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      sha256: "91bd59303e9f769f108f8df05e371341b15d59e995e6806aefab827b58336675"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.2"
  platform:
    dependency: transitive
    description:
@@ -557,6 +613,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "0.7.7"
+  timezone:
+    dependency: transitive
+    description:
+      name: timezone
+      sha256: "784a5e34d2eb62e1326f24d6f600aaaee452eb8ca8ef2f384a59244e292d158b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.11.0"
  typed_data:
    dependency: transitive
    description:
@@ -605,6 +669,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "1.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      sha256: "971043b3a0d3da28727e40ed3e0b5d18b742fa5a68665cca88e74b7876d5e025"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.6.1"
 sdks:
-  dart: ">=3.9.0 <4.0.0"
-  flutter: ">=3.35.0"
+  dart: ">=3.10.0 <4.0.0"
+  flutter: ">=3.38.1"
--- a/client_app/pubspec.yaml
+++ b/client_app/pubspec.yaml
@@ -33,6 +33,7 @@ dependencies:

  # Navigation
  go_router: ^13.2.1
+  flutter_local_notifications: ^21.0.0

 dev_dependencies:
  flutter_test:
--- a/client_app/windows/flutter/generated_plugins.cmake
+++ b/client_app/windows/flutter/generated_plugins.cmake
@@ -8,6 +8,7 @@ list(APPEND FLUTTER_PLUGIN_LIST
 )

 list(APPEND FLUTTER_FFI_PLUGIN_LIST
+  flutter_local_notifications_windows
 )

 set(PLUGIN_BUNDLED_LIBRARIES)
--- a/mitra_app/android/app/build.gradle.kts
+++ b/mitra_app/android/app/build.gradle.kts
@@ -11,6 +11,7 @@ android {
    ndkVersion = flutter.ndkVersion

    compileOptions {
+        isCoreLibraryDesugaringEnabled = true
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
    }
@@ -39,6 +40,10 @@ android {
    }
 }

+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.4")
+}
+
 flutter {
    source = "../.."
 }
--- a/mitra_app/lib/core/api/api_client.dart
+++ b/mitra_app/lib/core/api/api_client.dart
@@ -32,8 +32,4 @@ class ApiClient {
    final response = await _dio.post(path, data: data);
    return response.data as Map<String, dynamic>;
  }
-
-  Future<Response> getStream(String path) async {
-    return _dio.get(path, options: Options(responseType: ResponseType.stream));
-  }
 }
--- a/mitra_app/lib/core/auth/auth_bloc.dart
+++ b/mitra_app/lib/core/auth/auth_bloc.dart
@@ -55,7 +55,7 @@ class AuthBloc extends Bloc<AuthEvent, AuthState> {
  final _auth = FirebaseAuth.instance;
  ConfirmationResult? _webConfirmationResult;

-  AuthBloc({required this.apiClient}) : super(AuthInitial()) {
+  AuthBloc({required this.apiClient}) : super(AuthLoading()) {
    on<AppStarted>(_onAppStarted);
    on<PhoneOtpRequested>(_onPhoneOtpRequested);
    on<OtpVerified>(_onOtpVerified);
--- a/mitra_app/lib/core/chat/chat_request_bloc.dart
+++ b/mitra_app/lib/core/chat/chat_request_bloc.dart
@@ -2,8 +2,11 @@ import 'dart:async';
 import 'dart:convert';
 import 'package:dio/dio.dart';
 import 'package:equatable/equatable.dart';
+import 'package:firebase_auth/firebase_auth.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:web_socket_channel/web_socket_channel.dart';
 import '../api/api_client.dart';
+import '../constants.dart';

 // Events
 abstract class ChatRequestEvent extends Equatable {
@@ -21,6 +24,8 @@ class _RequestReceived extends ChatRequestEvent {
  List<Object?> get props => [data];
 }

+class _ConnectionError extends ChatRequestEvent {}
+
 class AcceptRequest extends ChatRequestEvent {
  final String sessionId;
  AcceptRequest(this.sessionId);
@@ -70,49 +75,76 @@ class ChatRequestError extends ChatRequestState {
 // Bloc
 class ChatRequestBloc extends Bloc<ChatRequestEvent, ChatRequestState> {
  final ApiClient apiClient;
-  StreamSubscription? _sseSubscription;
+  WebSocketChannel? _channel;
+  StreamSubscription? _wsSubscription;

  ChatRequestBloc({required this.apiClient}) : super(ChatRequestIdle()) {
    on<StartListening>(_onStartListening);
    on<StopListening>(_onStopListening);
    on<_RequestReceived>(_onRequestReceived);
+    on<_ConnectionError>(_onConnectionError);
    on<AcceptRequest>(_onAcceptRequest);
    on<DeclineRequest>(_onDeclineRequest);
  }

  Future<void> _onStartListening(StartListening event, Emitter<ChatRequestState> emit) async {
-    _stopSSE();
+    _closeWebSocket();
    emit(ChatRequestListening());
-    _listenToSSE();
+    await _connectWebSocket();
  }

  Future<void> _onStopListening(StopListening event, Emitter<ChatRequestState> emit) async {
-    _stopSSE();
+    _closeWebSocket();
    emit(ChatRequestIdle());
  }

-  void _listenToSSE() {
-    apiClient.getStream('/api/mitra/chat-requests/incoming').then((response) {
-      final stream = response.data.stream as Stream<List<int>>;
-      _sseSubscription = stream
-          .transform(utf8.decoder)
-          .transform(const LineSplitter())
-          .where((line) => line.startsWith('data: '))
-          .map((line) => jsonDecode(line.substring(6)) as Map<String, dynamic>)
-          .listen(
-            (data) => add(_RequestReceived(data)),
-            onError: (_) {},
+  Future<void> _connectWebSocket() async {
+    try {
+      final user = FirebaseAuth.instance.currentUser;
+      if (user == null) return;
+
+      final token = await user.getIdToken();
+      final wsUrl = ApiClient.baseUrl
+          .replaceFirst('https://', 'wss://')
+          .replaceFirst('http://', 'ws://');
+
+      _channel = WebSocketChannel.connect(Uri.parse('$wsUrl/api/shared/ws'));
+
+      _wsSubscription = _channel!.stream.listen(
+        (raw) {
+          final data = jsonDecode(raw as String) as Map<String, dynamic>;
+          if (data['type'] == WsMessage.authOk) return; // Auth confirmed, no action needed
+          add(_RequestReceived(data));
+        },
+        onError: (_) => add(_ConnectionError()),
+        onDone: () => add(_ConnectionError()),
      );
-    }).catchError((_) {});
+
+      // Authenticate without session_id — just for receiving notifications
+      _channel!.sink.add(jsonEncode({
+        'type': WsMessage.auth,
+        'token': token,
+      }));
+    } catch (_) {
+      add(_ConnectionError());
+    }
+  }
+
+  Future<void> _onConnectionError(_ConnectionError event, Emitter<ChatRequestState> emit) async {
+    _closeWebSocket();
+    // Stay in listening state — FCM will still deliver notifications
+    if (state is! ChatRequestIdle) {
+      emit(ChatRequestListening());
+    }
  }

  Future<void> _onRequestReceived(_RequestReceived event, Emitter<ChatRequestState> emit) async {
    final data = event.data;
    final type = data['type'] as String?;

-    if (type == 'chat_request') {
+    if (type == WsMessage.chatRequest) {
      emit(ChatRequestIncoming(data['session_id'] as String));
-    } else if (type == 'chat_request_closed') {
+    } else if (type == WsMessage.chatRequestClosed) {
      // Request was taken by another mitra or cancelled
      if (state is ChatRequestIncoming) {
        emit(ChatRequestListening());
@@ -148,14 +180,16 @@ class ChatRequestBloc extends Bloc<ChatRequestEvent, ChatRequestState> {
    emit(ChatRequestListening());
  }

-  void _stopSSE() {
-    _sseSubscription?.cancel();
-    _sseSubscription = null;
+  void _closeWebSocket() {
+    _wsSubscription?.cancel();
+    _wsSubscription = null;
+    _channel?.sink.close();
+    _channel = null;
  }

  @override
  Future<void> close() {
-    _stopSSE();
+    _closeWebSocket();
    return super.close();
  }
 }
--- a/mitra_app/lib/core/chat/extension_bloc.dart
+++ b/mitra_app/lib/core/chat/extension_bloc.dart
@@ -1,3 +1,4 @@
+import 'package:dio/dio.dart';
 import 'package:equatable/equatable.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../api/api_client.dart';
@@ -65,10 +66,16 @@ class ExtensionBloc extends Bloc<ExtensionEvent, ExtensionState> {
      } else {
        emit(ExtensionIdle());
      }
-    } catch (e) {
+    } on DioException catch (e) {
+      final code = e.response?.data?['error']?['code'];
+      if (code == 'EXTENSION_RESOLVED') {
+        // Extension already timed out or resolved — move to goodbye
+        emit(ExtensionShowGoodbye());
+      } else {
        emit(ExtensionError('Gagal merespon perpanjangan.'));
      }
    }
+  }

  Future<void> _onSubmitGoodbye(SubmitGoodbye event, Emitter<ExtensionState> emit) async {
    emit(ExtensionSubmitting());
--- a/mitra_app/lib/core/chat/mitra_chat_bloc.dart
+++ b/mitra_app/lib/core/chat/mitra_chat_bloc.dart
@@ -5,6 +5,7 @@ import 'package:firebase_auth/firebase_auth.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:web_socket_channel/web_socket_channel.dart';
 import '../api/api_client.dart';
+import '../constants.dart';

 // Events
 abstract class MitraChatEvent extends Equatable {
@@ -86,6 +87,7 @@ class ChatConnected extends MitraChatState {
    bool? sessionExpired,
    bool? sessionClosing,
    Map<String, dynamic>? extensionRequest,
+    bool clearExtensionRequest = false,
  }) {
    return ChatConnected(
      messages: messages ?? this.messages,
@@ -93,7 +95,7 @@ class ChatConnected extends MitraChatState {
      remainingSeconds: remainingSeconds ?? this.remainingSeconds,
      sessionExpired: sessionExpired ?? this.sessionExpired,
      sessionClosing: sessionClosing ?? this.sessionClosing,
-      extensionRequest: extensionRequest ?? this.extensionRequest,
+      extensionRequest: clearExtensionRequest ? null : (extensionRequest ?? this.extensionRequest),
    );
  }

@@ -121,8 +123,8 @@ class ChatMessage {
    required this.id,
    required this.senderType,
    required this.content,
-    this.type = 'text',
-    this.status = 'sent',
+    this.type = MessageType.text,
+    this.status = MessageStatus.sent,
    required this.createdAt,
  });

@@ -160,14 +162,27 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
    emit(ChatConnecting());

    try {
+      // Check session status before connecting
+      final sessionInfo = await apiClient.get('/api/shared/chat/${event.sessionId}/info');
+      final sessionData = sessionInfo['data'] as Map<String, dynamic>?;
+      final sessionStatus = sessionData?['status'] as String?;
+      if (sessionStatus == SessionStatus.completed ||
+          sessionStatus == SessionStatus.cancelled ||
+          sessionStatus == SessionStatus.expired) {
+        emit(ChatError('Sesi sudah berakhir.'));
+        return;
+      }
+
+      final isClosing = sessionStatus == SessionStatus.closing;
+
      final response = await apiClient.get('/api/shared/chat/${event.sessionId}/messages');
      final messagesData = response['data'] as List<dynamic>;
      final messages = messagesData.map((m) => ChatMessage(
        id: m['id'] as String,
        senderType: m['sender_type'] as String,
        content: m['content'] as String,
-        type: m['type'] as String? ?? 'text',
-        status: m['status'] as String? ?? 'sent',
+        type: m['type'] as String? ?? MessageType.text,
+        status: m['status'] as String? ?? MessageStatus.sent,
        createdAt: DateTime.parse(m['created_at'] as String),
      )).toList();

@@ -188,12 +203,15 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
      );

      _channel!.sink.add(jsonEncode({
-        'type': 'auth',
+        'type': WsMessage.auth,
        'token': token,
        'session_id': event.sessionId,
      }));

-      emit(ChatConnected(messages: messages));
+      emit(ChatConnected(
+        messages: messages,
+        sessionClosing: isClosing,
+      ));
    } catch (e) {
      emit(ChatError('Gagal terhubung ke chat.'));
    }
@@ -211,7 +229,7 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
    final tempId = 'temp_${DateTime.now().millisecondsSinceEpoch}';
    final msg = ChatMessage(
      id: tempId,
-      senderType: 'mitra',
+      senderType: UserType.mitra,
      content: event.content,
      status: 'sending',
      createdAt: DateTime.now(),
@@ -220,7 +238,7 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
    emit(current.copyWith(messages: [...current.messages, msg]));

    _channel!.sink.add(jsonEncode({
-      'type': 'message',
+      'type': WsMessage.message,
      'content': event.content,
      '_temp_id': tempId,
    }));
@@ -228,17 +246,17 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {

  void _onSendTyping(SendTyping event, Emitter<MitraChatState> emit) {
    if (_channel == null) return;
-    _channel!.sink.add(jsonEncode({'type': 'typing'}));
+    _channel!.sink.add(jsonEncode({'type': WsMessage.typing}));
  }

  void _onMarkDelivered(MarkMessagesDelivered event, Emitter<MitraChatState> emit) {
    if (_channel == null) return;
-    _channel!.sink.add(jsonEncode({'type': 'delivered', 'message_ids': event.messageIds}));
+    _channel!.sink.add(jsonEncode({'type': WsMessage.delivered, 'message_ids': event.messageIds}));
  }

  void _onMarkRead(MarkMessagesRead event, Emitter<MitraChatState> emit) {
    if (_channel == null) return;
-    _channel!.sink.add(jsonEncode({'type': 'read', 'message_ids': event.messageIds}));
+    _channel!.sink.add(jsonEncode({'type': WsMessage.read, 'message_ids': event.messageIds}));
  }

  void _onMessageReceived(_MessageReceived event, Emitter<MitraChatState> emit) {
@@ -248,30 +266,30 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
    final type = data['type'] as String?;

    switch (type) {
-      case 'auth_ok':
+      case WsMessage.authOk:
        break;

-      case 'message':
+      case WsMessage.message:
        final msg = ChatMessage(
          id: data['message_id'] as String,
          senderType: data['sender_type'] as String,
          content: data['content'] as String,
-          type: data['message_type'] as String? ?? 'text',
-          status: 'sent',
+          type: data['message_type'] as String? ?? MessageType.text,
+          status: MessageStatus.sent,
          createdAt: DateTime.parse(data['created_at'] as String),
        );
        emit(current.copyWith(messages: [...current.messages, msg]));
        add(MarkMessagesDelivered([msg.id]));
        break;

-      case 'message_ack':
+      case WsMessage.messageAck:
        final messageId = data['message_id'] as String;
        final status = data['status'] as String;
        final updatedMessages = current.messages.map((m) {
          if (m.status == 'sending') return m.copyWith(status: status);
          return m;
        }).toList();
-        final idx = updatedMessages.indexWhere((m) => m.status == status && m.senderType == 'mitra');
+        final idx = updatedMessages.indexWhere((m) => m.status == status && m.senderType == UserType.mitra);
        if (idx >= 0) {
          final old = updatedMessages[idx];
          updatedMessages[idx] = ChatMessage(
@@ -286,7 +304,7 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
        emit(current.copyWith(messages: updatedMessages));
        break;

-      case 'message_status':
+      case WsMessage.messageStatus:
        final messageIds = (data['message_ids'] as List<dynamic>).cast<String>();
        final status = data['status'] as String;
        final updatedMessages = current.messages.map((m) {
@@ -296,7 +314,7 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
        emit(current.copyWith(messages: updatedMessages));
        break;

-      case 'typing':
+      case WsMessage.typing:
        emit(current.copyWith(isOtherTyping: true));
        _typingTimer?.cancel();
        _typingTimer = Timer(const Duration(seconds: 3), () {
@@ -306,27 +324,27 @@ class MitraChatBloc extends Bloc<MitraChatEvent, MitraChatState> {
        });
        break;

-      case 'session_timer':
+      case WsMessage.sessionTimer:
        emit(current.copyWith(remainingSeconds: data['remaining_seconds'] as int?));
        break;

-      case 'session_expired':
+      case WsMessage.sessionExpired:
        emit(current.copyWith(sessionExpired: true));
        break;

-      case 'extension_request':
+      case WsMessage.extensionRequest:
        emit(current.copyWith(extensionRequest: data));
        break;

-      case 'session_resumed':
-        emit(current.copyWith(sessionExpired: false, extensionRequest: null));
+      case WsMessage.sessionResumed:
+        emit(current.copyWith(sessionExpired: false, sessionClosing: false, clearExtensionRequest: true));
        break;

-      case 'session_closing':
-        emit(current.copyWith(sessionClosing: true));
+      case WsMessage.sessionClosing:
+        emit(current.copyWith(sessionClosing: true, clearExtensionRequest: true));
        break;

-      case 'session_completed':
+      case WsMessage.sessionCompleted:
        _cleanup();
        break;
    }
--- a/mitra_app/lib/core/constants.dart
+++ b/mitra_app/lib/core/constants.dart
@@ -0,0 +1,83 @@
+/// User types
+class UserType {
+  static const customer = 'customer';
+  static const mitra = 'mitra';
+  UserType._();
+}
+
+/// Chat session statuses
+class SessionStatus {
+  static const searching = 'searching';
+  static const pendingAcceptance = 'pending_acceptance';
+  static const pendingPayment = 'pending_payment';
+  static const active = 'active';
+  static const extending = 'extending';
+  static const closing = 'closing';
+  static const completed = 'completed';
+  static const cancelled = 'cancelled';
+  static const expired = 'expired';
+  SessionStatus._();
+}
+
+/// Chat message statuses
+class MessageStatus {
+  static const sent = 'sent';
+  static const delivered = 'delivered';
+  static const read = 'read';
+  MessageStatus._();
+}
+
+/// Chat message types
+class MessageType {
+  static const text = 'text';
+  MessageType._();
+}
+
+/// Session extension statuses
+class ExtensionStatus {
+  static const pending = 'pending';
+  static const accepted = 'accepted';
+  static const rejected = 'rejected';
+  static const timeout = 'timeout';
+  ExtensionStatus._();
+}
+
+/// WebSocket message types
+class WsMessage {
+  // Auth
+  static const auth = 'auth';
+  static const authOk = 'auth_ok';
+  static const error = 'error';
+
+  // Chat
+  static const message = 'message';
+  static const messageAck = 'message_ack';
+  static const messageStatus = 'message_status';
+  static const typing = 'typing';
+
+  // Pairing
+  static const chatRequest = 'chat_request';
+  static const chatRequestClosed = 'chat_request_closed';
+  static const paired = 'paired';
+
+  // Session lifecycle
+  static const sessionTimer = 'session_timer';
+  static const sessionExpired = 'session_expired';
+  static const sessionClosing = 'session_closing';
+  static const sessionCompleted = 'session_completed';
+  static const sessionPaused = 'session_paused';
+  static const sessionResumed = 'session_resumed';
+
+  // Extension
+  static const extensionRequest = 'extension_request';
+  static const extensionResponse = 'extension_response';
+
+  // Delivery
+  static const delivered = 'delivered';
+  static const read = 'read';
+
+  // Early end
+  static const earlyEnd = 'early_end';
+
+  WsMessage._();
+}
--- a/mitra_app/lib/core/notifications/notification_service.dart
+++ b/mitra_app/lib/core/notifications/notification_service.dart
@@ -0,0 +1,95 @@
+import 'dart:convert';
+import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter_local_notifications/flutter_local_notifications.dart';
+import 'package:go_router/go_router.dart';
+
+/// Handles FCM foreground/background notifications and local notification display.
+class NotificationService {
+  static final _localNotifications = FlutterLocalNotificationsPlugin();
+  static GoRouter? _router;
+
+  static const _channel = AndroidNotificationChannel(
+    'chat_messages',
+    'Chat Messages',
+    description: 'Notifications for incoming chat messages',
+    importance: Importance.high,
+  );
+
+  static Future<void> initialize(GoRouter router) async {
+    _router = router;
+
+    // Create Android notification channel
+    await _localNotifications
+        .resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()
+        ?.createNotificationChannel(_channel);
+
+    // Initialize local notifications
+    await _localNotifications.initialize(
+      settings: const InitializationSettings(
+        android: AndroidInitializationSettings('@mipmap/ic_launcher'),
+        iOS: DarwinInitializationSettings(),
+      ),
+      onDidReceiveNotificationResponse: _onNotificationTap,
+    );
+
+    // FCM foreground messages → show local notification
+    FirebaseMessaging.onMessage.listen(_onForegroundMessage);
+
+    // FCM notification tap (app was in background)
+    FirebaseMessaging.onMessageOpenedApp.listen(_onMessageOpenedApp);
+
+    // Check if app was opened from a terminated state via notification
+    final initialMessage = await FirebaseMessaging.instance.getInitialMessage();
+    if (initialMessage != null) {
+      _navigateFromMessage(initialMessage.data);
+    }
+  }
+
+  static void _onForegroundMessage(RemoteMessage message) {
+    final notification = message.notification;
+    if (notification == null) return;
+
+    _localNotifications.show(
+      id: notification.hashCode,
+      title: notification.title,
+      body: notification.body,
+      notificationDetails: NotificationDetails(
+        android: AndroidNotificationDetails(
+          _channel.id,
+          _channel.name,
+          channelDescription: _channel.description,
+          importance: Importance.high,
+          priority: Priority.high,
+        ),
+        iOS: const DarwinNotificationDetails(
+          presentAlert: true,
+          presentBadge: true,
+          presentSound: true,
+        ),
+      ),
+      payload: jsonEncode(message.data),
+    );
+  }
+
+  static void _onNotificationTap(NotificationResponse response) {
+    if (response.payload == null) return;
+    try {
+      final data = jsonDecode(response.payload!) as Map<String, dynamic>;
+      _navigateFromMessage(data);
+    } catch (_) {}
+  }
+
+  static void _onMessageOpenedApp(RemoteMessage message) {
+    _navigateFromMessage(message.data);
+  }
+
+  static void _navigateFromMessage(Map<String, dynamic> data) {
+    final sessionId = data['session_id'] as String?;
+    if (sessionId == null || _router == null) return;
+
+    final type = data['type'] as String?;
+    if (type == 'chat_message' || type == 'chat_request') {
+      _router!.push('/chat/session/$sessionId');
+    }
+  }
+}
--- a/mitra_app/lib/features/chat/screens/active_sessions_screen.dart
+++ b/mitra_app/lib/features/chat/screens/active_sessions_screen.dart
@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:go_router/go_router.dart';
 import '../../../core/api/api_client.dart';

 class ActiveSessionsScreen extends StatefulWidget {
@@ -72,14 +73,19 @@ class _ActiveSessionsScreenState extends State<ActiveSessionsScreen> {
                  itemCount: _sessions.length,
                  itemBuilder: (context, index) {
                    final session = _sessions[index];
+                    final customerName = session['customer_display_name'] as String? ?? 'Customer';
                    return ListTile(
-                      leading: const Icon(Icons.person),
-                      title: Text(session['customer_display_name'] as String? ?? 'Customer'),
+                      leading: const Icon(Icons.chat),
+                      title: Text(customerName),
                      subtitle: Text('Status: ${session['status']}'),
                      trailing: TextButton(
                        onPressed: () => _endSession(session['id'] as String),
                        child: const Text('Akhiri', style: TextStyle(color: Colors.red)),
                      ),
+                      onTap: () => context.push(
+                        '/chat/session/${session['id']}',
+                        extra: {'customerName': customerName},
+                      ),
                    );
                  },
                ),
--- a/mitra_app/lib/features/chat/screens/chat_transcript_screen.dart
+++ b/mitra_app/lib/features/chat/screens/chat_transcript_screen.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import '../../../core/api/api_client.dart';
+import '../../../core/constants.dart';

 class MitraChatTranscriptScreen extends StatefulWidget {
  final String sessionId;
@@ -47,7 +48,7 @@ class _MitraChatTranscriptScreenState extends State<MitraChatTranscriptScreen> {
              padding: const EdgeInsets.all(16),
              children: [
                ..._messages.map((m) {
-                  final isMe = m['sender_type'] == 'mitra';
+                  final isMe = m['sender_type'] == UserType.mitra;
                  final time = DateTime.parse(m['created_at'] as String).toLocal();
                  return Align(
                    alignment: isMe ? Alignment.centerRight : Alignment.centerLeft,
@@ -79,7 +80,7 @@ class _MitraChatTranscriptScreenState extends State<MitraChatTranscriptScreen> {
                  const SizedBox(height: 8),
                  ..._closures.map((c) => Card(
                    child: ListTile(
-                      title: Text(c['user_type'] == 'mitra' ? 'Kamu' : 'Customer'),
+                      title: Text(c['user_type'] == UserType.mitra ? 'Kamu' : 'Customer'),
                      subtitle: Text(c['message'] as String),
                    ),
                  )),
--- a/mitra_app/lib/features/chat/screens/mitra_chat_screen.dart
+++ b/mitra_app/lib/features/chat/screens/mitra_chat_screen.dart
@@ -4,6 +4,7 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:go_router/go_router.dart';
 import '../../../core/chat/mitra_chat_bloc.dart';
 import '../../../core/chat/extension_bloc.dart';
+import '../../../core/constants.dart';

 class MitraChatScreen extends StatefulWidget {
  final String sessionId;
@@ -20,8 +21,15 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
  final _scrollController = ScrollController();
  Timer? _typingThrottle;

+  @override
+  void initState() {
+    super.initState();
+    context.read<MitraChatBloc>().add(ConnectChat(widget.sessionId));
+  }
+
  @override
  void dispose() {
+    context.read<MitraChatBloc>().add(DisconnectChat());
    _messageController.dispose();
    _scrollController.dispose();
    _typingThrottle?.cancel();
@@ -63,7 +71,7 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
            if (state is ChatConnected) {
              _scrollToBottom();
              final unread = state.messages
-                  .where((m) => m.senderType == 'customer' && m.status != 'read')
+                  .where((m) => m.senderType == UserType.customer && m.status != MessageStatus.read)
                  .map((m) => m.id)
                  .toList();
              if (unread.isNotEmpty) {
@@ -147,7 +155,7 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
            itemCount: state.messages.length,
            itemBuilder: (context, index) {
              final msg = state.messages[index];
-              final isMe = msg.senderType == 'mitra';
+              final isMe = msg.senderType == UserType.mitra;
              return _buildMessageBubble(msg, isMe);
            },
          ),
@@ -204,11 +212,11 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
    switch (status) {
      case 'sending':
        return const Icon(Icons.access_time, size: 14, color: Colors.grey);
-      case 'sent':
+      case MessageStatus.sent:
        return const Icon(Icons.check, size: 14, color: Colors.grey);
-      case 'delivered':
+      case MessageStatus.delivered:
        return const Icon(Icons.done_all, size: 14, color: Colors.grey);
-      case 'read':
+      case MessageStatus.read:
        return const Icon(Icons.done_all, size: 14, color: Colors.blue);
      default:
        return const SizedBox.shrink();
@@ -249,6 +257,10 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
    final duration = request['duration_minutes'] as int?;
    final extensionId = request['extension_id'] as String?;

+    return BlocBuilder<ExtensionBloc, ExtensionState>(
+      builder: (context, extState) {
+        final isResponding = extState is ExtensionResponding;
+
        return Center(
          child: Padding(
            padding: const EdgeInsets.all(32),
@@ -261,14 +273,17 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
                const SizedBox(height: 8),
                Text('Customer ingin perpanjang $duration menit', textAlign: TextAlign.center),
                const SizedBox(height: 24),
+                if (isResponding)
+                  const CircularProgressIndicator()
+                else
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      ElevatedButton(
                        style: ElevatedButton.styleFrom(backgroundColor: Colors.green),
-                  onPressed: () => context.read<ExtensionBloc>().add(RespondToExtension(
+                        onPressed: extensionId == null ? null : () => context.read<ExtensionBloc>().add(RespondToExtension(
                          sessionId: widget.sessionId,
-                    extensionId: extensionId!,
+                          extensionId: extensionId,
                          accepted: true,
                        )),
                        child: const Text('Terima', style: TextStyle(color: Colors.white)),
@@ -276,9 +291,9 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
                      const SizedBox(width: 16),
                      ElevatedButton(
                        style: ElevatedButton.styleFrom(backgroundColor: Colors.red),
-                  onPressed: () => context.read<ExtensionBloc>().add(RespondToExtension(
+                        onPressed: extensionId == null ? null : () => context.read<ExtensionBloc>().add(RespondToExtension(
                          sessionId: widget.sessionId,
-                    extensionId: extensionId!,
+                          extensionId: extensionId,
                          accepted: false,
                        )),
                        child: const Text('Tolak', style: TextStyle(color: Colors.white)),
@@ -289,16 +304,17 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
            ),
          ),
        );
+      },
+    );
  }

  Widget _buildGoodbyeView(BuildContext context, ExtensionState extState) {
    final controller = TextEditingController();
-    return Center(
-      child: Padding(
+    return SingleChildScrollView(
      padding: const EdgeInsets.all(32),
      child: Column(
-          mainAxisAlignment: MainAxisAlignment.center,
        children: [
+          const SizedBox(height: 48),
            const Icon(Icons.waving_hand, size: 64, color: Colors.amber),
            const SizedBox(height: 16),
            const Text('Pesan Penutup', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
@@ -331,7 +347,6 @@ class _MitraChatScreenState extends State<MitraChatScreen> {
            ),
          ],
        ),
-      ),
    );
  }
 }
--- a/mitra_app/lib/features/home/home_screen.dart
+++ b/mitra_app/lib/features/home/home_screen.dart
@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:go_router/go_router.dart';
 import '../../core/auth/auth_bloc.dart';
 import '../../core/status/status_bloc.dart';
 import '../../core/chat/chat_request_bloc.dart';
@@ -65,9 +66,11 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
            if (state is ChatRequestIncoming) {
              _showIncomingRequest(state.sessionId);
            } else if (state is ChatRequestAccepted) {
-              ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('Sesi baru diterima!')),
-              );
+              final session = state.session;
+              final sessionId = session['session_id'] as String? ?? session['id'] as String;
+              context.push('/chat/session/$sessionId', extra: {
+                'customerName': session['customer_display_name'] as String? ?? 'Customer',
+              });
            }
          },
        ),
@@ -177,7 +180,7 @@ class _ActiveSessionsButton extends StatelessWidget {
            leading: const Icon(Icons.chat_bubble_outline),
            title: const Text('Sesi Aktif'),
            trailing: const Icon(Icons.chevron_right),
-            onTap: () => Navigator.of(context).pushNamed('/sessions'),
+            onTap: () => context.push('/sessions'),
          ),
        ),
        Card(
@@ -185,7 +188,7 @@ class _ActiveSessionsButton extends StatelessWidget {
            leading: const Icon(Icons.history),
            title: const Text('Riwayat Chat'),
            trailing: const Icon(Icons.chevron_right),
-            onTap: () => Navigator.of(context).pushNamed('/chat/history'),
+            onTap: () => context.push('/chat/history'),
          ),
        ),
      ],
--- a/mitra_app/lib/features/splash/splash_screen.dart
+++ b/mitra_app/lib/features/splash/splash_screen.dart
@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+
+class SplashScreen extends StatelessWidget {
+  const SplashScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Scaffold(
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            Icon(Icons.favorite, size: 80, color: Colors.blue),
+            SizedBox(height: 24),
+            Text(
+              'Halo Bestie Mitra',
+              style: TextStyle(fontSize: 28, fontWeight: FontWeight.bold),
+            ),
+            SizedBox(height: 32),
+            CircularProgressIndicator(),
+          ],
+        ),
+      ),
+    );
+  }
+}
--- a/mitra_app/lib/main.dart
+++ b/mitra_app/lib/main.dart
@@ -9,6 +9,7 @@ import 'core/status/status_bloc.dart';
 import 'core/chat/chat_request_bloc.dart';
 import 'core/chat/mitra_chat_bloc.dart';
 import 'core/chat/extension_bloc.dart';
+import 'core/notifications/notification_service.dart';
 import 'firebase_options.dart';
 import 'router.dart';

@@ -43,6 +44,7 @@ class _AppState extends State<App> with WidgetsBindingObserver {
    _apiClient = ApiClient();
    _authBloc = AuthBloc(apiClient: _apiClient)..add(AppStarted());
    _router = buildRouter(_authBloc);
+    NotificationService.initialize(_router);
    _statusBloc = StatusBloc(apiClient: _apiClient);
    _chatRequestBloc = ChatRequestBloc(apiClient: _apiClient);
    _registerFcmToken();
--- a/mitra_app/lib/router.dart
+++ b/mitra_app/lib/router.dart
@@ -2,6 +2,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 import 'core/auth/auth_bloc.dart';
+import 'features/splash/splash_screen.dart';
 import 'features/auth/screens/login_screen.dart';
 import 'features/auth/screens/otp_screen.dart';
 import 'features/home/home_screen.dart';
@@ -26,19 +27,26 @@ class _BlocRefreshNotifier extends ChangeNotifier {

 GoRouter buildRouter(AuthBloc authBloc) {
  return GoRouter(
-    initialLocation: '/login',
+    initialLocation: '/splash',
    refreshListenable: _BlocRefreshNotifier(authBloc),
    redirect: (context, state) {
      final authState = authBloc.state;
+      final isSplash = state.matchedLocation == '/splash';
      final isAuthRoute = state.matchedLocation.startsWith('/login') ||
          state.matchedLocation.startsWith('/otp');

-      if (authState is AuthLoading) return null;
-      if (authState is AuthAuthenticated) return isAuthRoute ? '/home' : null;
-      if (!isAuthRoute) return '/login';
+      // Show splash while loading
+      if (authState is AuthLoading) return isSplash ? null : '/splash';
+
+      if (authState is AuthAuthenticated) {
+        return (isSplash || isAuthRoute) ? '/home' : null;
+      }
+      if (!isAuthRoute && !isSplash) return '/login';
+      if (isSplash) return '/login';
      return null;
    },
    routes: [
+      GoRoute(path: '/splash', builder: (_, __) => const SplashScreen()),
      GoRoute(path: '/login', builder: (_, __) => const LoginScreen()),
      GoRoute(path: '/otp', builder: (context, state) => OtpScreen(phone: state.extra as String)),
      GoRoute(path: '/home', builder: (_, __) => const HomeScreen()),
--- a/mitra_app/pubspec.lock
+++ b/mitra_app/pubspec.lock
@@ -9,6 +9,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "1.3.35"
+  args:
+    dependency: transitive
+    description:
+      name: args
+      sha256: d0481093c50b1da8910eb0bb301626d4d8eb7284aa739614d2b394ee09e3ea04
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.7.0"
  async:
    dependency: transitive
    description:
@@ -65,6 +73,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "3.0.7"
+  dbus:
+    dependency: transitive
+    description:
+      name: dbus
+      sha256: d0c98dcd4f5169878b6cf8f6e0a52403a9dff371a3e2f019697accbf6f44a270
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.12"
  dio:
    dependency: "direct main"
    description:
@@ -97,6 +113,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "1.3.3"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      sha256: "6d7fd89431262d8f3125e81b50d3847a091d846eafcd4fdb88dd06f36d705a45"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.0"
  firebase_auth:
    dependency: "direct main"
    description:
@@ -190,6 +214,38 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "3.0.2"
+  flutter_local_notifications:
+    dependency: "direct main"
+    description:
+      name: flutter_local_notifications
+      sha256: "0d9035862236fe38250fe1644d7ed3b8254e34a21b2c837c9f539fbb3bba5ef1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "21.0.0"
+  flutter_local_notifications_linux:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_linux
+      sha256: e0f25e243c6c44c825bbbc6b2b2e76f7d9222362adcfe9fd780bf01923c840bd
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.0.0"
+  flutter_local_notifications_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_platform_interface
+      sha256: e7db3d5b49c2b7ecc68deba4aaaa67a348f92ee0fef34c8e4b4459dbef0d7307
+      url: "https://pub.dev"
+    source: hosted
+    version: "11.0.0"
+  flutter_local_notifications_windows:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_windows
+      sha256: "3a2654ba104fbb52c618ebed9def24ef270228470718c43b3a6afcd5c81bef0c"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.0"
  flutter_test:
    dependency: "direct dev"
    description: flutter
@@ -208,6 +264,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "13.2.5"
+  http:
+    dependency: transitive
+    description:
+      name: http
+      sha256: "87721a4a50b19c7f1d49001e51409bddc46303966ce89a65af4f4e6004896412"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.6.0"
  http_parser:
    dependency: transitive
    description:
@@ -304,6 +368,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "1.9.1"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      sha256: "91bd59303e9f769f108f8df05e371341b15d59e995e6806aefab827b58336675"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.2"
  plugin_platform_interface:
    dependency: transitive
    description:
@@ -373,6 +445,14 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "0.7.7"
+  timezone:
+    dependency: transitive
+    description:
+      name: timezone
+      sha256: "784a5e34d2eb62e1326f24d6f600aaaee452eb8ca8ef2f384a59244e292d158b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.11.0"
  typed_data:
    dependency: transitive
    description:
@@ -413,6 +493,22 @@ packages:
      url: "https://pub.dev"
    source: hosted
    version: "2.4.5"
+  xdg_directories:
+    dependency: transitive
+    description:
+      name: xdg_directories
+      sha256: "7a3f37b05d989967cdddcbb571f1ea834867ae2faa29725fd085180e0883aa15"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      sha256: "971043b3a0d3da28727e40ed3e0b5d18b742fa5a68665cca88e74b7876d5e025"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.6.1"
 sdks:
-  dart: ">=3.8.0-0 <4.0.0"
-  flutter: ">=3.18.0-18.0.pre.54"
+  dart: ">=3.10.0 <4.0.0"
+  flutter: ">=3.38.1"
--- a/mitra_app/pubspec.yaml
+++ b/mitra_app/pubspec.yaml
@@ -26,6 +26,7 @@ dependencies:

  # Navigation
  go_router: ^13.2.1
+  flutter_local_notifications: ^21.0.0

 dev_dependencies:
  flutter_test:
--- a/requirement/phase3.md
+++ b/requirement/phase3.md
@@ -14,6 +14,16 @@

 # Functional Requirement

+## Chat Opening
+Functinal Requirement:
+- Customer Application can start request chat session
+- Customer App will shows dialog to choose selection of time and price. This phase it will be mock only. later it will be taken from Configuration of Control Center
+- If enabled, Customer App will shows free trial instead of price selection. But this free trial only shows when following logic met:
+    * Free trial is enabled
+    * Customer never made any transaction (including free trial)
+- When customer choose Free trial, the chat session period will be determine by Control Center
+- After selection (either paid, or free trial), Backend will start pairing process
+
 ## Bi Directional Chat
 Functional requirement:
 - After pairing success, both Mitra and Customer can communicate bidirectional
@@ -22,17 +32,30 @@ Functional requirement:
 - All chat must be recorded in database in chronological order
 - When app is opened after shutdown, it must be able to populate all conversation along
 - User (both Mitra and Customer) must be able to re read all chat history
+- Each message will have sent (one check), delivered (double check) and read (double check with blue color) status
+- When one of the person type, application will shows typing indicator

 ## Chat Closure
- Chat session is a limited time session. For now, it is 2 minutes, but make it configurable through control center
 - When chat is going to end (1 minutes left), shows remaining time on the chat screen
 - When chat session is finished there will be following functionality:
    - Customer Application:
        - Show dialog window whether Customer want to extend the session
        - If Customer do not want to extend, show closing message input
-    - 
-
+        - If Customer want to extend, show dialog selection of time and price. This phase it will be mock only. 
+        - Wait for Mitra confirmation, shows "Menunggu konfirmasi Bestie"
+            - If Mitra approve, prepare for payment process in this step
+            - If Mitra reject, show closing message input
+    - Mitra Application
+        - If customer do not want to extend, show closing message input
+        - If Customer extend, send confirmation to Mitra that customer want to extend for x minutes. Mitra can do following things:
+            - Accept, and session extended for x minutes
+            - Reject, show closing message input

+## Chat History
+Functional Requirement:
+- On Customer App, customer can see previous chat history, along with session information such as Mitra name (bestie name) and closure message
+- On Mitra App, mitra can see previous chat history, along with session information such as Customer name and closure message
+- Both will able to see communication history (chat message)