fix(tests): isolate test symlink manipulation via t.TempDir() to prevent overwriting ~/.claude

Le test TestKillAndRecreatePoolSessions appelait executeSwitch() qui faisait
flipSymlink() sur le VRAI $HOME via os.UserHomeDir(). Resultat: ~/.claude
etait repointe vers une cible /tmp/... qui disparaissait au reboot, rendant
Claude Code inutilisable apres redemarrage.

Fix:
- Ajout du champ AccountSwitcher.homeDir (override pour tests).
- Nouveau helper resolveHomeDir() qui retourne homeDir si defini, sinon
  os.UserHomeDir().
- flipSymlink() et resumeContextDir() utilisent maintenant resolveHomeDir().
- Le test TestKillAndRecreatePoolSessions assigne a.homeDir = t.TempDir()
  avant executeSwitch().

Verifie: go test ./... passe et /home/ubuntu/.claude reste intact.

internal/switcher/account_switcher.go

@@ -0,0 +1,281 @@
+// Package switcher implements the account-switcher state machine.
+// It is the only component allowed to flip the active Claude account.
+package switcher
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"forge.secuaas.ovh/olivier/claude-failover/internal/config"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/notify"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/quota"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/state"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/tmux"
+)
+
+// SwitchState represents the current phase of a failover operation.
+type SwitchState string
+
+const (
+	StateNormal    SwitchState = "normal"
+	StateSaving    SwitchState = "saving"
+	StateSwitching SwitchState = "switching"
+	StateResuming  SwitchState = "resuming"
+)
+
+// resumeRe matches `claude --resume <uuid>` in pane capture output.
+var resumeRe = regexp.MustCompile(`claude\s+--resume\s+([a-f0-9-]{36})`)
+
+// reMinutes matches "in N minutes" in a reset-time string.
+var reMinutes = regexp.MustCompile(`in\s+(\d+)\s+minute`)
+
+// reHours matches "in N hours" in a reset-time string.
+var reHours = regexp.MustCompile(`in\s+(\d+)\s+hour`)
+
+// AccountSwitcher consumes SwitchRequests and orchestrates account failover:
+// save session context → flip ~/.claude symlink → restart sessions.
+type AccountSwitcher struct {
+	tmux         tmux.Client
+	state        *state.State
+	config       *config.Config
+	switchCh     <-chan quota.SwitchRequest
+	notifier     *notify.Notifier
+	currentState SwitchState
+	logger       *log.Logger
+	// homeDir is the directory containing the .claude symlink. Overridable for tests.
+	// When empty, os.UserHomeDir() is used.
+	homeDir string
+}
+
+// New creates an AccountSwitcher.
+// notifier may be nil; notifications are skipped when absent.
+func New(
+	tc tmux.Client,
+	s *state.State,
+	cfg *config.Config,
+	switchCh <-chan quota.SwitchRequest,
+	notifier *notify.Notifier,
+) *AccountSwitcher {
+	return &AccountSwitcher{
+		tmux:         tc,
+		state:        s,
+		config:       cfg,
+		switchCh:     switchCh,
+		notifier:     notifier,
+		currentState: StateNormal,
+		logger:       log.Default(),
+	}
+}
+
+// Run starts the switcher event loop until ctx is cancelled.
+func (a *AccountSwitcher) Run(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case req := <-a.switchCh:
+			a.executeSwitch(req)
+		}
+	}
+}
+
+// executeSwitch performs the full failover sequence.
+func (a *AccountSwitcher) executeSwitch(req quota.SwitchRequest) {
+	a.logger.Printf("[switcher] SWAP initiated from=%q reset=%q", req.From, req.ResetTime)
+
+	// 1. SAVING — capture resume UUIDs from all working sessions.
+	a.currentState = StateSaving
+	a.saveAllSessions()
+
+	// 2. SWITCHING — find target, flip symlink, restart sessions.
+	a.currentState = StateSwitching
+	target := a.findTargetAccount(req.From)
+	if target == nil {
+		a.logger.Printf("[switcher] no alternate account found for %q — aborting swap", req.From)
+		a.currentState = StateNormal
+		return
+	}
+
+	if err := a.flipSymlink(target.Home); err != nil {
+		a.logger.Printf("[switcher] flipSymlink error: %v", err)
+	}
+	a.killAllPoolSessions()
+	a.recreatePoolSessions()
+
+	// Update active account.
+	a.state.SetActiveAccount(target.Name)
+
+	// 3. RESUMING — sessions are alive, dispatcher will fill them.
+	a.currentState = StateResuming
+
+	// 4. Notify.
+	msg := fmt.Sprintf("Switch %s → %s (reset: %s)", req.From, target.Name, req.ResetTime)
+	a.logger.Printf("[switcher] SWAP complete: %s", msg)
+	if a.notifier != nil {
+		a.notifier.Telegram("🔄 " + msg) //nolint:errcheck
+	}
+
+	// 5. Schedule return to primary account if reset time is known.
+	if req.ResetTime != "" {
+		go a.scheduleReturn(req.From, req.ResetTime)
+	}
+
+	a.currentState = StateNormal
+}
+
+// saveAllSessions captures the resume UUID for every working session.
+func (a *AccountSwitcher) saveAllSessions() {
+	a.state.ForEachWorking(func(name string, _ *state.SessionState) {
+		tail, err := a.tmux.CapturePaneTail(name, 200)
+		if err != nil {
+			return
+		}
+		uuid := extractResumeUUID(tail)
+		if uuid == "" {
+			return
+		}
+		dir := a.resumeContextDir()
+		os.MkdirAll(dir, 0700)
+		path := filepath.Join(dir, name+"-resume-id.txt")
+		os.WriteFile(path, []byte(uuid), 0600)
+		a.logger.Printf("[switcher] saved resume UUID for %q", name)
+	})
+}
+
+// resolveHomeDir returns the configured homeDir (test override) or the real
+// user home. Tests MUST set a.homeDir to a tmpdir to avoid clobbering the
+// production ~/.claude symlink.
+func (a *AccountSwitcher) resolveHomeDir() (string, error) {
+	if a.homeDir != "" {
+		return a.homeDir, nil
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", fmt.Errorf("UserHomeDir: %w", err)
+	}
+	return home, nil
+}
+
+// flipSymlink replaces ~/.claude with a symlink to targetHome.
+// All paths come from config — no hardcoded values.
+func (a *AccountSwitcher) flipSymlink(targetHome string) error {
+	home, err := a.resolveHomeDir()
+	if err != nil {
+		return err
+	}
+	claudeLink := filepath.Join(home, ".claude")
+	os.Remove(claudeLink)
+	if err := os.Symlink(targetHome, claudeLink); err != nil {
+		return fmt.Errorf("symlink %s → %s: %w", claudeLink, targetHome, err)
+	}
+	a.logger.Printf("[switcher] ~/.claude → %s", targetHome)
+	return nil
+}
+
+// killAllPoolSessions kills all autonomous and dedicated pool sessions.
+func (a *AccountSwitcher) killAllPoolSessions() {
+	prefix := a.config.Pool.Autonomous.Prefix
+	if prefix == "" {
+		prefix = "ccl-auto-"
+	}
+	for i := 0; i < a.config.Pool.Autonomous.Max; i++ {
+		a.tmux.KillSession(sessionName(prefix, i)) //nolint:errcheck
+	}
+	for _, ds := range a.config.Pool.Dedicated {
+		a.tmux.KillSession(ds.Name) //nolint:errcheck
+	}
+}
+
+// recreatePoolSessions creates fresh pool sessions after a switch.
+func (a *AccountSwitcher) recreatePoolSessions() {
+	prefix := a.config.Pool.Autonomous.Prefix
+	if prefix == "" {
+		prefix = "ccl-auto-"
+	}
+	for i := 0; i < a.config.Pool.Autonomous.Min; i++ {
+		name := sessionName(prefix, i)
+		if err := a.tmux.CreateSession(name, ""); err != nil {
+			a.logger.Printf("[switcher] recreate autonomous %q: %v", name, err)
+		}
+	}
+	for _, ds := range a.config.Pool.Dedicated {
+		if err := a.tmux.CreateSession(ds.Name, ds.Project); err != nil {
+			a.logger.Printf("[switcher] recreate dedicated %q: %v", ds.Name, err)
+		}
+	}
+}
+
+// findTargetAccount returns the first account that is not currentAccount.
+func (a *AccountSwitcher) findTargetAccount(currentAccount string) *config.AccountConfig {
+	for i := range a.config.Accounts {
+		if a.config.Accounts[i].Name != currentAccount {
+			return &a.config.Accounts[i]
+		}
+	}
+	return nil
+}
+
+// scheduleReturn waits for the quota to reset then switches back to primaryAccount.
+func (a *AccountSwitcher) scheduleReturn(primaryAccount, resetTime string) {
+	dur := timeUntilReset(resetTime) + 5*time.Minute
+	a.logger.Printf("[switcher] return to %q scheduled in %v", primaryAccount, dur.Round(time.Minute))
+	time.Sleep(dur)
+	a.executeSwitch(quota.SwitchRequest{
+		From: a.state.ActiveAccount(),
+		To:   primaryAccount,
+	})
+}
+
+// extractResumeUUID finds a Claude resume UUID in pane output.
+func extractResumeUUID(content string) string {
+	m := resumeRe.FindStringSubmatch(content)
+	if len(m) >= 2 {
+		return m[1]
+	}
+	return ""
+}
+
+// resumeContextDir returns the directory for per-session resume UUIDs.
+// Honours a.homeDir override so tests never write to the real ~/.claude-context.
+func (a *AccountSwitcher) resumeContextDir() string {
+	home, _ := a.resolveHomeDir()
+	return filepath.Join(home, ".claude-context")
+}
+
+// timeUntilReset parses a reset-time string and returns the duration.
+// Returns a 2-hour fallback when parsing fails.
+func timeUntilReset(resetTime string) time.Duration {
+	lower := strings.ToLower(strings.TrimSpace(resetTime))
+	if m := reMinutes.FindStringSubmatch(lower); len(m) >= 2 {
+		n, _ := strconv.Atoi(m[1])
+		return time.Duration(n) * time.Minute
+	}
+	if m := reHours.FindStringSubmatch(lower); len(m) >= 2 {
+		n, _ := strconv.Atoi(m[1])
+		return time.Duration(n) * time.Hour
+	}
+	return 2 * time.Hour
+}
+
+func sessionName(prefix string, i int) string {
+	return prefix + itoa(i)
+}
+
+func itoa(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	b := make([]byte, 0, 10)
+	for n > 0 {
+		b = append([]byte{byte('0' + n%10)}, b...)
+		n /= 10
+	}
+	return string(b)
+}

internal/switcher/account_switcher_test.go

@@ -0,0 +1,166 @@
+package switcher
+
+import (
+	"testing"
+	"time"
+
+	"forge.secuaas.ovh/olivier/claude-failover/internal/config"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/quota"
+	"forge.secuaas.ovh/olivier/claude-failover/internal/state"
+)
+
+// mockTmux for switcher tests.
+type mockTmux struct {
+	sessions    map[string]bool
+	paneOutput  map[string]string
+	killCalls   []string
+	createCalls []string
+}
+
+func newMockTmux() *mockTmux {
+	return &mockTmux{
+		sessions:   make(map[string]bool),
+		paneOutput: make(map[string]string),
+	}
+}
+
+func (m *mockTmux) HasSession(name string) bool { return m.sessions[name] }
+func (m *mockTmux) CreateSession(name, _ string) error {
+	m.sessions[name] = true
+	m.createCalls = append(m.createCalls, name)
+	return nil
+}
+func (m *mockTmux) KillSession(name string) error {
+	delete(m.sessions, name)
+	m.killCalls = append(m.killCalls, name)
+	return nil
+}
+func (m *mockTmux) SendKeys(_, _ string) error { return nil }
+func (m *mockTmux) CapturePaneTail(session string, _ int) (string, error) {
+	return m.paneOutput[session], nil
+}
+
+// TestFindTargetAccount returns the first account that differs from current.
+func TestFindTargetAccount(t *testing.T) {
+	tc := newMockTmux()
+	s := state.New("")
+	cfg := &config.Config{
+		Accounts: []config.AccountConfig{
+			{Name: "compte1", Priority: 1},
+			{Name: "compte2", Priority: 2},
+		},
+	}
+	a := New(tc, s, cfg, make(chan quota.SwitchRequest), nil)
+
+	target := a.findTargetAccount("compte1")
+	if target == nil || target.Name != "compte2" {
+		t.Errorf("expected compte2, got %v", target)
+	}
+}
+
+// TestFindTargetAccountSingleAccount returns nil when only one account exists.
+func TestFindTargetAccountSingleAccount(t *testing.T) {
+	tc := newMockTmux()
+	s := state.New("")
+	cfg := &config.Config{
+		Accounts: []config.AccountConfig{{Name: "solo"}},
+	}
+	a := New(tc, s, cfg, make(chan quota.SwitchRequest), nil)
+
+	if got := a.findTargetAccount("solo"); got != nil {
+		t.Errorf("expected nil for single account, got %v", got)
+	}
+}
+
+// TestExtractResumeUUID parses UUID from pane output.
+func TestExtractResumeUUID(t *testing.T) {
+	input := "$ claude --resume a1b2c3d4-e5f6-7890-abcd-ef1234567890 --model sonnet"
+	got := extractResumeUUID(input)
+	want := "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
+	if got != want {
+		t.Errorf("expected %q, got %q", want, got)
+	}
+}
+
+// TestExtractResumeUUIDMissing returns empty string when no UUID present.
+func TestExtractResumeUUIDMissing(t *testing.T) {
+	if got := extractResumeUUID("no uuid here"); got != "" {
+		t.Errorf("expected empty, got %q", got)
+	}
+}
+
+// TestTimeUntilReset parses minute and hour formats correctly.
+func TestTimeUntilReset(t *testing.T) {
+	cases := []struct {
+		input string
+		want  time.Duration
+	}{
+		{"in 45 minutes", 45 * time.Minute},
+		{"in 2 hours", 2 * time.Hour},
+		{"in 1 hour", 1 * time.Hour},
+		{"", 2 * time.Hour},
+		{"8pm", 2 * time.Hour}, // fallback for unrecognised formats
+	}
+	for _, c := range cases {
+		if got := timeUntilReset(c.input); got != c.want {
+			t.Errorf("timeUntilReset(%q) = %v, want %v", c.input, got, c.want)
+		}
+	}
+}
+
+// TestKillAndRecreatePoolSessions verifies that executeSwitch restarts sessions.
+func TestKillAndRecreatePoolSessions(t *testing.T) {
+	tc := newMockTmux()
+	tc.sessions["ccl-auto-0"] = true
+	tc.sessions["ccl-auto-1"] = true
+	tc.sessions["dedicated-1"] = true
+
+	s := state.New("")
+	s.SetActiveAccount("compte1")
+
+	cfg := &config.Config{
+		Accounts: []config.AccountConfig{
+			{Name: "compte1", Home: t.TempDir()},
+			{Name: "compte2", Home: t.TempDir()},
+		},
+		Pool: config.PoolConfig{
+			Dedicated:  []config.DedicatedSession{{Name: "dedicated-1", Project: "/tmp"}},
+			Autonomous: config.AutonomousConfig{Prefix: "ccl-auto-", Min: 2, Max: 2},
+		},
+	}
+
+	a := New(tc, s, cfg, make(chan quota.SwitchRequest), nil)
+	// CRITICAL: isolate symlink manipulation in a tmpdir so the test never
+	// touches the real ~/.claude (regression: a reboot used to leave Claude
+	// Code unusable because the test had repointed ~/.claude to /tmp/...).
+	a.homeDir = t.TempDir()
+	a.executeSwitch(quota.SwitchRequest{From: "compte1"})
+
+	// Active account must have changed.
+	if got := s.ActiveAccount(); got != "compte2" {
+		t.Errorf("expected active account compte2, got %q", got)
+	}
+
+	// All old sessions must have been killed.
+	for _, name := range []string{"ccl-auto-0", "ccl-auto-1", "dedicated-1"} {
+		found := false
+		for _, k := range tc.killCalls {
+			if k == name {
+				found = true
+				break
+			}
+		}
+		if !found {
+			t.Errorf("expected %q to be killed", name)
+		}
+	}
+
+	// Min pool sessions must be recreated.
+	recreated := map[string]bool{}
+	for _, c := range tc.createCalls {
+		recreated[c] = true
+	}
+	if !recreated["ccl-auto-0"] || !recreated["ccl-auto-1"] {
+		t.Errorf("expected autonomous sessions recreated; createCalls=%v", tc.createCalls)
+	}
+}