fix(session): WebSocket auto-reconnect with exponential backoff (#18)

[ghzhost]

Resumo

Implementa reconexão automática com backoff exponencial quando a conexão WebSocket cai, conforme solicitado na #18.

O que muda

• scheduleReconnect(attempt): calcula o delay (1s → 2s → 4s → … → 30s), atualiza o status visível para o jogador ("Reconectando… (intento 1/6, en 2s)") e agenda o próximo intento com setTimeout.
• connectSocket(attempt): cria um novo WebSocket reutilizando os handlers onopen e onmessage do socket original, sem duplicar lógica.
• Máximo de 6 tentativas; ao esgotar, mostra mensagem clara pedindo reload.
• O timeout pendente é cancelado no cleanup do useEffect (unmount ou troca de conexão).

Critérios de aceitação (do issue)

• Reconexão automática com backoff exponencial e teto de tentativas
• Estado visível: "reconectando…" com contagem regressiva e número de intento
• Após esgotar os intentos: botão/mensagem de reload (mensagem de erro clara)
• Preserva o personaje selecionado (não recarrega o fluxo de seleção)
• Cleanup correto — sem memory leaks nem reconexões fantasma após unmount

O que NÃO está neste PR (escopo conservador)

• Botão manual "Reconectar agora" na UI (requer mudanças no HUD/status component — pode ser follow-up)
• visibilitychange/pagehide listener (pode ser adicionado em follow-up sem mudar esta lógica)

Arquivos

• frontend/components/game/session/useGameSession.ts

[ghzhost]

✅ CI Status Update

Frontend lint is now passing. Fixed ESLint error react-hooks/rules-of-hooks by replacing useRef (which cannot be called inside a useEffect callback) with a plain let variable — correct since the timeout ID only needs to live within the single effect closure.

CI results (latest push 2f819f7)

Job	Result
Gitar	✅ success
Server (typecheck, lint, build)	✅ success
Frontend (typecheck, lint, build)	✅ success (lint error fixed)
Docker build checks	✅ success
Gitleaks Security Scan	✅ success
API (typecheck, test, build)	❌ pre-existing failures

Pre-existing API test failures (not caused by this PR)

• market.integration.test.ts fails with ENOENT: .../api/src/jsons/npcs.json → tracked in Falta api/src/jsons/npcs.json en el repositorio y el test de market no puede correr #83
• platform.integration.test.ts ranking endpoint returns 500 → tracked in El endpoint de ranking devuelve 500 en un entorno limpio #84

These failures exist on main branch CI (red since PR #81). This PR introduces no new test failures.

What this PR implements (issue #18)

• Automatic WebSocket reconnect with exponential backoff (1s → 2s → 4s → … → 30s)
• Max 6 retry attempts before asking user to reload
• Visible reconnecting status: "Reconectando… (intento N/6, en Xs)"
• Clean cleanup on useEffect teardown (no stale timers)
• Preserves all original ping/keepalive behavior

[ghzhost]

Pushed commit 0b73da2 addressing the review findings:

• Parameterized socket handlers: connectSocket attaches clean onopen/onmessage/onerror/onclose closures bound to the current socket instance ws and validates isCurrentSocketInstance(ws).
• Duplicate reconnect debounce: scheduleReconnect checks reconnectTimeoutId !== null before setting a new timer to prevent concurrent timeouts from firing from both onerror and onclose.
• Reset attempt count: successful onopen clears any pending timer and future drops restart with attempt 0.

[ghzhost]

✅ Fix: Reconnect attempt counter now resets after successful connection

Pushed commit 74829bc addressing the last remaining review finding (gitar-bot⚠️ "Reconnect attempt counter never resets after success").

What was wrong

ws.onerror and ws.onclose were defined once inside connectSocket, closing over the reconnectAttempt parameter. After a successful reconnect at attempt N, those handlers still referenced N — so any subsequent disconnect would start the backoff at the wrong level (e.g., attempt 3 → 16 s delay on the very first reconnect after a clean session).

What changed

Inside ws.onopen, after validating the socket instance and clearing any pending timeout, the handlers are re-assigned with scheduleReconnect(0) — a fresh closure that resets the counter to 0. The original handlers lower in connectSocket still fire during the initial connection phase (before onopen fires), so backoff during a connection failure still works correctly.

Bonus: ws.onopen now emits { connected: true, connecting: false } so the UI status is accurate after a reconnect.

All four gitar-bot findings are now addressed. CI should pass.

[gitar-bot]

CI failed: ESLint failed due to an invalid React Hook call inside a callback in the frontend session hook, and backend integration tests failed due to a missing npcs.json game data file.

Overview

Two distinct failure patterns were identified across the CI jobs: an ESLint error in the frontend build pipeline caused by an improper React Hook call, and backend integration test failures caused by a missing required game data file (npcs.json).

Failures

Frontend ESLint React Hook Violation (confidence: high)

• Type: tooling
• Affected jobs: 96777344118
• Related to change: yes
• Root cause: React Hook useRef was called inside a callback at line 232 of frontend/components/game/session/useGameSession.ts, violating React's rules of hooks.
• Suggested fix: Move the useRef call out of the callback and to the top level of the useGameSession custom hook.

Backend Integration Test Missing Game Data File (confidence: high)

• Type: test
• Affected jobs: 96779130519, 96968307914, 96777343913
• Related to change: unclear
• Root cause: The backend integration test suite failed with ENOENT when trying to open api/src/jsons/npcs.json during NPC data loading, causing downstream 500 errors in market and public endpoint tests.
• Suggested fix: Ensure that required game data JSON files (such as npcs.json) are present in api/src/jsons/ or generated/copied prior to running the integration tests.

Summary

• Change-related failures: 1 ESLint tooling failure in the frontend session hook due to incorrect React Hook usage.
• Infrastructure/flaky failures: 0 (all failures are actual code or test setup issues).
• Recommended action: Fix the useRef placement in useGameSession.ts and verify that the npcs.json fixture is correctly included in the backend test environment.

Code Review ✅ Approved 4 resolved / 4 findings

Adds WebSocket auto-reconnect with exponential backoff and a 6-attempt limit, addressing the useRef hook misuse, stale socket closures, duplicate reconnect scheduling, and unreset attempt counter findings.

✅ 4 resolved

✅ Bug: useRef() called inside useEffect throws Invalid hook call

📄 frontend/components/game/session/useGameSession.ts:232 📄 frontend/components/game/session/useGameSession.ts:585-588
const reconnectTimeoutIdRef = useRef<number | null>(null); is called inside the useEffect callback (line 232), not at component top level. React only allows hooks during render; when the effect runs during commit the dispatcher is the context-only dispatcher and useRef throws "Invalid hook call", crashing the session on mount. Replace it with a plain closure variable (e.g. let reconnectTimeoutId: number | null = null;) or hoist a real ref to the component body.

✅ Bug: Reused onopen/onmessage close over stale socket, reconnect fails

📄 frontend/components/game/session/useGameSession.ts:315-322 📄 frontend/components/game/session/useGameSession.ts:454-457 📄 frontend/components/game/session/useGameSession.ts:540-541
connectSocket assigns ws.onopen = socket.onopen and ws.onmessage = socket.onmessage (lines 540-541), but those handlers close over the original socket variable. On the new connection isCurrentSocketInstance(socket) is false (websocketRef.current now points to ws), so onopen immediately calls socket.close(); return; without ever sending the connect-character packet, and onmessage drops every message. The reconnected socket therefore never authenticates or processes data, so reconnection silently never works. Factor the onopen/onmessage logic into functions parameterized by the active socket (or reference websocketRef.current) so the new ws is used.

✅ Bug: onerror and onclose both schedule reconnect, causing duplicates

📄 frontend/components/game/session/useGameSession.ts:512-520 📄 frontend/components/game/session/useGameSession.ts:543-557 📄 frontend/components/game/session/useGameSession.ts:564-571 📄 frontend/components/game/session/useGameSession.ts:573-581
On a dropped connection both onerror and onclose fire and each calls scheduleReconnect, which overwrites reconnectTimeoutIdRef.current with a new setTimeout. The first timeout is orphaned (cleanup can only clear the last one) yet still fires, producing two concurrent connectSocket calls and duplicate WebSockets. Guard against this by clearing any pending timeout at the start of scheduleReconnect (or bail if one is already scheduled).

✅ Bug: Reconnect attempt counter never resets after success

📄 frontend/components/game/session/useGameSession.ts:519 📄 frontend/components/game/session/useGameSession.ts:548 📄 frontend/components/game/session/useGameSession.ts:560 📄 frontend/components/game/session/useGameSession.ts:493-507 📄 frontend/components/game/session/useGameSession.ts:558-572
After a successful reconnect at attempt N, the new socket's onerror/onclose call scheduleReconnect(reconnectAttempt) with the same N rather than 0, because the reused onopen never resets the counter. A connection that recovers and later drops again resumes the backoff from N and can exhaust MAX_RECONNECT_ATTEMPTS even though it had been healthy. Reset the attempt count to 0 once the connection successfully opens.

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