fix(quota): add cooldown + 2-poll confirmation to prevent swap ping-pong

Anthropic HTTP 500 errors surface in the TUI with payloads containing
"rate limit" text, which the monitor was matching against quotaPatterns
and treating as a real 429 quota hit. With no cooldown and no
confirmation, a burst of 500s produced sub-minute ping-pong swaps that
tore down user sessions.

Two-layer fix:
- quota.reactivate_cooldown (already in config, 5m) now gates the
  monitor too — not just the dispatcher. A completed swap suppresses
  further detection for the cooldown window.
- A hit with no parseable reset time is treated as suspected only on
  the first poll; a second consecutive poll is required before
  emitting SwapRequested. Legitimate 429s with "resets in ..." still
  swap instantly on the first detection.

Adds state.RecordSwap / LastSwapInfo for the cooldown, and a
forensic log line on every detection: trigger_session, matched
pattern, 120-char pane snippet.

Tests cover: instant swap with reset, 2-poll confirmation without
reset, and suspected-state reset on recovery.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

VERSION.md

@@ -1,4 +1,69 @@
-# Version actuelle : 0.2.0
+# Version actuelle : 0.2.2
+
+## [0.2.2] - 2026-04-15
+**Type:** Patch — Confirmation requise pour les faux positifs (root cause)
+
+### Corrigé
+- **Cause racine du ping-pong** : les erreurs HTTP 500 transitoires d'Anthropic
+  contiennent le texte "rate limit" dans leur payload (`{"type":"api_error",...}`
+  avec des traces mentionnant "rate limit"). Le monitor les confondait avec de
+  vrais 429 quota hits. La v0.2.1 cassait la boucle via cooldown, mais un swap
+  par salve de 500s pouvait encore tuer les sessions dédiées.
+- Le nouveau log forensique v0.2.1 a révélé exactement ça (snippet capturé :
+  `API Error: 500 {"type":"error","error":{"type":"api_error",...}`).
+
+### Ajouté
+- **Confirmation 2-polls pour les hits sans reset time** : si `extractResetTime`
+  ne trouve rien (= pas un vrai 429), le monitor marque l'état `suspectedHitAt`
+  et attend le poll suivant. Le swap n'est émis que si la détection persiste.
+  Un hit isolé (= erreur 500 transitoire) est absorbé sans swap.
+- Un vrai 429 (avec `resets in 45 minutes` ou `resets at 8pm`) continue à
+  déclencher un swap instantané.
+- `Monitor.suspectedHitAt` (not locked — only touched from poll goroutine).
+- 3 nouveaux tests : `TestPollTriggersSwitchOnTwoBlockedPoolWithReset`,
+  `TestPollRequiresConfirmationWhenNoResetTime`,
+  `TestPollSuspectedHitClearedOnRecovery`.
+
+### Tests effectués
+- ✅ `go test ./...` — full suite passe
+- ✅ Service redémarré, état consistant
+
+### Fichiers modifiés
+- `internal/quota/monitor.go`
+- `internal/quota/monitor_test.go`
+
+## [0.2.1] - 2026-04-15
+**Type:** Patch — Fix boucle de swaps infinis (ping-pong)
+
+### Corrigé
+- **Boucle infinie de swaps** : le monitor pouvait émettre des `SwapRequested`
+  toutes les 30s, créant un ping-pong entre comptes quand du texte de pane
+  (anciens errors Anthropic 500 / TUI banners) matchait `quotaPatterns` avec
+  `reset=""`. En prod, interval observé descendant jusqu'à 1 min.
+- **Cause racine** : aucun cooldown global entre swaps dans la boucle de
+  détection. La config `quota.reactivate_cooldown` (5m) existait mais n'était
+  utilisée que par le dispatcher, pas par le monitor.
+
+### Ajouté
+- `state.QuotaState.LastSwapAt/LastSwapFrom/LastSwapTo` + `RecordSwap()` +
+  `LastSwapInfo()` pour tracker le dernier swap.
+- `monitor.poll()` vérifie `quota.reactivate_cooldown` avant de déclencher un
+  swap. Log explicite quand le cooldown bloque : `[quota] swap cooldown active`.
+- Log forensique détaillé lors d'un `SwapRequested` : session déclencheuse,
+  pattern matché, snippet du pane (120 chars). Ex :
+  `trigger_session="ccl-1-conformvault" pattern="rate limit" snippet="..."`.
+- `switcher.executeSwitch` appelle `state.RecordSwap()` après `SetActiveAccount`.
+
+### Tests effectués
+- ✅ `go build ./cmd/claude-failover` OK
+- ✅ `go test ./internal/quota/... ./internal/state/... ./internal/switcher/...` OK
+- ✅ Binaire installé dans `/usr/local/bin/claude-failover`
+- ✅ Service redémarré — pas de swap intempestif depuis
+
+### Fichiers modifiés
+- `internal/state/state.go`
+- `internal/quota/monitor.go`
+- `internal/switcher/account_switcher.go`
 
 ## [0.2.0] - 2026-04-14
 **Type:** Minor — Implémentation des goroutines Phase 2

internal/quota/monitor.go

@@ -46,6 +46,12 @@ type Monitor struct {
 	switchCh chan SwitchRequest
 	interval time.Duration
 	logger   *log.Logger
+	// suspectedHitAt tracks the first poll that detected a quota pattern
+	// without a parseable reset time. A second consecutive hit is required
+	// before emitting SwapRequested; a single-poll hit is ignored as likely
+	// transient (e.g. Anthropic 500s containing "rate limit" in payload).
+	// Mutated only from poll(), which runs on a single goroutine — no lock.
+	suspectedHitAt time.Time
 }
 
 // New creates a Monitor with defaults from cfg.
@@ -89,9 +95,33 @@ func (m *Monitor) poll() {
 		return
 	}
 
+	// Cooldown guard: after a recent swap, refuse to trigger another one until
+	// the cooldown elapses. Prevents ping-pong when the freshly-activated
+	// account surfaces transient errors whose text happens to match
+	// quotaPatterns (e.g. Anthropic 500s rendered as "rate limit" in the TUI).
+	cooldown := m.config.Quota.ReactivateCooldown.Duration
+	if cooldown == 0 {
+		cooldown = 10 * time.Minute
+	}
+	if lastAt, _, lastTo := m.state.LastSwapInfo(); !lastAt.IsZero() {
+		if since := time.Since(lastAt); since < cooldown {
+			m.logger.Printf("[quota] swap cooldown active (since=%v < cooldown=%v, last_to=%q) — skipping detection",
+				since.Round(time.Second), cooldown, lastTo)
+			return
+		}
+	}
+
 	blockedPool := 0
 	blockedInteractive := 0
 	var resetTime string
+	var firstPattern, firstSession, firstSnippet string
+	recordHit := func(session, tail string) {
+		if firstPattern == "" {
+			firstPattern = firstMatchingPattern(tail)
+			firstSession = session
+			firstSnippet = snippet(tail)
+		}
+	}
 
 	prefix := m.config.Pool.Autonomous.Prefix
 	if prefix == "" {
@@ -109,6 +139,7 @@ func (m *Monitor) poll() {
 		}
 		if isQuotaExhausted(tail) {
 			blockedPool++
+			recordHit(name, tail)
 			if rt := extractResetTime(tail); rt != "" {
 				resetTime = rt
 			}
@@ -125,25 +156,52 @@ func (m *Monitor) poll() {
 		}
 		if isQuotaExhausted(tail) {
 			blockedInteractive++
+			recordHit(ds.Name, tail)
 			if rt := extractResetTime(tail); rt != "" {
 				resetTime = rt
 			}
 		}
 	}
 
-	if blockedPool >= 2 || blockedInteractive >= 1 {
+	if blockedPool < 2 && blockedInteractive < 1 {
+		// No detection — clear any suspected-hit state so future transient
+		// blips have to re-confirm from scratch.
+		if !m.suspectedHitAt.IsZero() {
+			m.logger.Printf("[quota] suspected hit cleared (no detection this poll)")
+			m.suspectedHitAt = time.Time{}
+		}
+		return
+	}
+
+	// When no reset time can be parsed, the "hit" might be a transient
+	// Anthropic 500 that happens to contain "rate limit" in its error
+	// payload. Require two consecutive polls detecting a hit before
+	// swapping, so a single-poll false positive is absorbed.
+	if resetTime == "" {
+		if m.suspectedHitAt.IsZero() {
+			m.suspectedHitAt = time.Now()
+			m.logger.Printf("[quota] suspected hit (no reset time): session=%q pattern=%q snippet=%q — awaiting confirmation next poll",
+				firstSession, firstPattern, firstSnippet)
+			return
+		}
+		// Second consecutive hit — proceed.
+		m.logger.Printf("[quota] hit confirmed across %v — proceeding with swap",
+			time.Since(m.suspectedHitAt).Round(time.Second))
+	}
+	m.suspectedHitAt = time.Time{}
+
 	req := SwitchRequest{
 		From:      m.state.ActiveAccount(),
 		ResetTime: resetTime,
 	}
 	select {
 	case m.switchCh <- req:
-			m.logger.Printf("[quota] SwapRequested: from=%s pool=%d interactive=%d reset=%q",
+		m.logger.Printf("[quota] SwapRequested: from=%s pool=%d interactive=%d reset=%q trigger_session=%q pattern=%q snippet=%q",
-				req.From, blockedPool, blockedInteractive, resetTime)
+			req.From, blockedPool, blockedInteractive, resetTime,
+			firstSession, firstPattern, firstSnippet)
 	default:
 		// Swap already pending — do not queue another.
 	}
-	}
 }
 
 // isQuotaPaused checks whether a swap is already in progress.
@@ -154,13 +212,30 @@ func (m *Monitor) isQuotaPaused() bool {
 
 // isQuotaExhausted returns true if the pane content indicates quota exhaustion.
 func isQuotaExhausted(paneContent string) bool {
+	return firstMatchingPattern(paneContent) != ""
+}
+
+// firstMatchingPattern returns the first quota pattern found in paneContent,
+// or "" if none match. Exposed for diagnostic logging.
+func firstMatchingPattern(paneContent string) string {
 	lower := strings.ToLower(paneContent)
 	for _, p := range quotaPatterns {
 		if strings.Contains(lower, p) {
-			return true
+			return p
 		}
 	}
-	return false
+	return ""
+}
+
+// snippet returns a 120-char single-line excerpt of pane content for logging.
+func snippet(s string) string {
+	s = strings.ReplaceAll(s, "\n", " ")
+	s = strings.ReplaceAll(s, "\r", "")
+	s = strings.TrimSpace(s)
+	if len(s) > 120 {
+		s = s[:120]
+	}
+	return s
 }
 
 // extractResetTime parses a reset time string from pane content.

internal/quota/monitor_test.go

@@ -69,13 +69,14 @@ func TestExtractResetTime(t *testing.T) {
 	}
 }
 
-// TestPollTriggersSwitchOnTwoBlockedPool verifies swap trigger for >=2 blocked pool sessions.
+// TestPollTriggersSwitchOnTwoBlockedPoolWithReset verifies a legitimate 429
-func TestPollTriggersSwitchOnTwoBlockedPool(t *testing.T) {
+// (reset time present) triggers a swap immediately on the first poll.
+func TestPollTriggersSwitchOnTwoBlockedPoolWithReset(t *testing.T) {
 	tc := newMockTmux()
 	tc.sessions["ccl-auto-0"] = true
 	tc.sessions["ccl-auto-1"] = true
-	tc.paneOutput["ccl-auto-0"] = "You've hit your limit for Claude Pro."
+	tc.paneOutput["ccl-auto-0"] = "You've hit your limit for Claude Pro. resets in 45 minutes"
-	tc.paneOutput["ccl-auto-1"] = "rate limit exceeded"
+	tc.paneOutput["ccl-auto-1"] = "rate limit exceeded — resets at 8pm"
 
 	s := state.New("")
 	s.SetActiveAccount("compte1")
@@ -93,13 +94,61 @@ func TestPollTriggersSwitchOnTwoBlockedPool(t *testing.T) {
 		if req.From != "compte1" {
 			t.Errorf("expected From=compte1, got %q", req.From)
 		}
+		if req.ResetTime == "" {
+			t.Errorf("expected non-empty ResetTime")
+		}
 	default:
 		t.Fatal("expected SwitchRequest on channel")
 	}
 }
 
-// TestPollTriggersSwitchOnOneBlockedInteractive verifies swap trigger for >=1 dedicated session.
+// TestPollRequiresConfirmationWhenNoResetTime verifies that a hit without a
-func TestPollTriggersSwitchOnOneBlockedInteractive(t *testing.T) {
+// parseable reset time does not trigger a swap on a single poll. A second
+// consecutive hit is required. This guards against transient Anthropic 500
+// errors whose payload happens to contain "rate limit".
+func TestPollRequiresConfirmationWhenNoResetTime(t *testing.T) {
+	tc := newMockTmux()
+	tc.sessions["my-session"] = true
+	tc.paneOutput["my-session"] = "quota exceeded" // no reset time
+
+	s := state.New("")
+	s.SetActiveAccount("compte1")
+
+	cfg := &config.Config{
+		Pool: config.PoolConfig{
+			Dedicated:  []config.DedicatedSession{{Name: "my-session"}},
+			Autonomous: config.AutonomousConfig{Max: 0},
+		},
+	}
+	m := New(tc, s, cfg)
+
+	// First poll — suspected only, no swap yet.
+	m.poll()
+	select {
+	case req := <-m.switchCh:
+		t.Fatalf("unexpected SwitchRequest on first poll: %+v", req)
+	default:
+	}
+
+	// Second poll — confirmed, swap emitted.
+	m.poll()
+	select {
+	case req := <-m.switchCh:
+		if req.From != "compte1" {
+			t.Errorf("expected From=compte1, got %q", req.From)
+		}
+		if req.ResetTime != "" {
+			t.Errorf("expected empty ResetTime, got %q", req.ResetTime)
+		}
+	default:
+		t.Fatal("expected SwitchRequest on confirmation poll")
+	}
+}
+
+// TestPollSuspectedHitClearedOnRecovery verifies a transient hit followed by
+// a clean poll does NOT trigger a swap on a subsequent hit — the suspected
+// state must be reset when detection clears.
+func TestPollSuspectedHitClearedOnRecovery(t *testing.T) {
 	tc := newMockTmux()
 	tc.sessions["my-session"] = true
 	tc.paneOutput["my-session"] = "quota exceeded"
@@ -114,15 +163,17 @@ func TestPollTriggersSwitchOnOneBlockedInteractive(t *testing.T) {
 		},
 	}
 	m := New(tc, s, cfg)
-	m.poll()
+
+	m.poll() // suspected
+	tc.paneOutput["my-session"] = "all good ❯ "
+	m.poll() // cleared
+	tc.paneOutput["my-session"] = "quota exceeded"
+	m.poll() // re-suspected, NOT confirmed yet
 
 	select {
 	case req := <-m.switchCh:
-		if req.From != "compte1" {
+		t.Fatalf("unexpected SwitchRequest after recovery: %+v", req)
-			t.Errorf("expected From=compte1, got %q", req.From)
-		}
 	default:
-		t.Fatal("expected SwitchRequest on channel")
 	}
 }
 

internal/state/state.go

@@ -24,6 +24,9 @@ type QuotaState struct {
 	Paused        bool       `json:"paused"`
 	ActiveAccount string     `json:"active_account"`
 	ResumeAt      *time.Time `json:"resume_at,omitempty"`
+	LastSwapAt    *time.Time `json:"last_swap_at,omitempty"`
+	LastSwapFrom  string     `json:"last_swap_from,omitempty"`
+	LastSwapTo    string     `json:"last_swap_to,omitempty"`
 }
 
 // State is the thread-safe runtime state persisted to a JSON file.
@@ -178,6 +181,31 @@ func (s *State) ActiveAccount() string {
 	return s.Quota.ActiveAccount
 }
 
+// RecordSwap stamps the time, source and target of the most recent account swap.
+// Used by the quota monitor to enforce a cooldown and avoid ping-pong loops
+// when transient upstream errors (e.g. Anthropic 500s mirrored as "rate limit"
+// text in the TUI) are misread as quota hits.
+func (s *State) RecordSwap(from, to string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	now := time.Now().UTC()
+	s.Quota.LastSwapAt = &now
+	s.Quota.LastSwapFrom = from
+	s.Quota.LastSwapTo = to
+	s.touch()
+}
+
+// LastSwapInfo returns the time, source and target of the most recent swap,
+// or a zero time and empty strings if no swap has occurred.
+func (s *State) LastSwapInfo() (time.Time, string, string) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	if s.Quota.LastSwapAt == nil {
+		return time.Time{}, "", ""
+	}
+	return *s.Quota.LastSwapAt, s.Quota.LastSwapFrom, s.Quota.LastSwapTo
+}
+
 // SetFailed marks the named session as failed and records the failure timestamp.
 // The task is preserved for potential requeue by the caller.
 func (s *State) SetFailed(name string) {

internal/switcher/account_switcher.go

@@ -109,8 +109,10 @@ func (a *AccountSwitcher) executeSwitch(req quota.SwitchRequest) {
 	a.killAllPoolSessions()
 	a.recreatePoolSessions()
 
-	// Update active account.
+	// Update active account and record the swap timestamp so the quota
+	// monitor can enforce a cooldown before requesting another one.
 	a.state.SetActiveAccount(target.Name)
+	a.state.RecordSwap(req.From, target.Name)
 
 	// 3. RESUMING — sessions are alive, dispatcher will fill them.
 	a.currentState = StateResuming