[client] UI refactor (#6069)

Refactor UI

---------

Co-authored-by: Eduard Gert <kontakt@eduardgert.de>
Co-authored-by: braginini <bangvalo@gmail.com>
Co-authored-by: Pascal Fischer <32096965+pascal-fischer@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: riccardom <riccardomanfrin@gmail.com>

client/internal/auth/pending_flow.go

@@ -0,0 +1,89 @@
+package auth
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+// PendingFlow stores an in-progress OAuth flow between the RPC that
+// initiates it (returns the verification URI to the UI) and the RPC
+// that waits for the user to complete it. The flow handle, the
+// device-code info, and the absolute expiry are kept together so the
+// waiting RPC can validate the device code and reuse the same flow.
+//
+// PendingFlow is safe for concurrent use; callers must not access the
+// stored fields directly.
+type PendingFlow struct {
+	mu         sync.Mutex
+	flow       OAuthFlow
+	info       AuthFlowInfo
+	expiresAt  time.Time
+	waitCancel context.CancelFunc
+}
+
+// NewPendingFlow returns an empty PendingFlow ready to be populated by Set.
+func NewPendingFlow() *PendingFlow {
+	return &PendingFlow{}
+}
+
+// Set stores the flow and its authorization info, computing the absolute
+// expiry from info.ExpiresIn (seconds, as returned by the IdP).
+func (p *PendingFlow) Set(flow OAuthFlow, info AuthFlowInfo) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.flow = flow
+	p.info = info
+	p.expiresAt = time.Now().Add(time.Duration(info.ExpiresIn) * time.Second)
+}
+
+// Get returns the stored flow, info, and whether a flow is currently
+// pending. Returns (nil, zero, false) after Clear or before Set.
+func (p *PendingFlow) Get() (OAuthFlow, AuthFlowInfo, bool) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.flow == nil {
+		return nil, AuthFlowInfo{}, false
+	}
+	return p.flow, p.info, true
+}
+
+// ExpiresAt returns the absolute expiry of the pending flow. Returns
+// the zero time when no flow is pending.
+func (p *PendingFlow) ExpiresAt() time.Time {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	return p.expiresAt
+}
+
+// SetWaitCancel records the cancel function for the goroutine currently
+// blocked in WaitToken so a new RequestAuth can preempt it.
+func (p *PendingFlow) SetWaitCancel(cancel context.CancelFunc) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.waitCancel = cancel
+}
+
+// CancelWait invokes and clears the stored wait-cancel, if any. Safe to
+// call when no wait is in progress.
+func (p *PendingFlow) CancelWait() {
+	p.mu.Lock()
+	cancel := p.waitCancel
+	p.waitCancel = nil
+	p.mu.Unlock()
+	if cancel != nil {
+		cancel()
+	}
+}
+
+// Clear resets the pending flow to empty. Any stored wait-cancel is
+// dropped without being invoked — call CancelWait first if the waiting
+// goroutine must be stopped.
+func (p *PendingFlow) Clear() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.flow = nil
+	p.info = AuthFlowInfo{}
+	p.expiresAt = time.Time{}
+	p.waitCancel = nil
+}