diff --git a/auth.go b/auth.go
index 5473c8b..403b236 100644
--- a/auth.go
+++ b/auth.go
@@ -174,13 +174,9 @@ func refreshAccessToken(
 	data.Set("grant_type", "refresh_token")
 	data.Set("refresh_token", refreshToken)
 	data.Set("client_id", cfg.ClientID)
-	if !cfg.IsPublicClient() {
-		data.Set("client_secret", cfg.ClientSecret)
-	}
+	cfg.setClientSecret(data)
 	// Server doesn't persist extra_claims across refresh, so re-send them.
-	if cfg.ExtraClaims != "" {
-		data.Set(extraClaimsFormKey, cfg.ExtraClaims)
-	}
+	cfg.setExtraClaims(data)
 
 	tokenResp, err := doTokenExchange(ctx, cfg, cfg.Endpoints.TokenURL, data,
 		func(errResp ErrorResponse, _ []byte) error {
diff --git a/browser_flow.go b/browser_flow.go
index 44f2b94..659a1b1 100644
--- a/browser_flow.go
+++ b/browser_flow.go
@@ -40,12 +40,8 @@ func exchangeCode(
 	data.Set("client_id", cfg.ClientID)
 	data.Set("code_verifier", codeVerifier)
 
-	if !cfg.IsPublicClient() {
-		data.Set("client_secret", cfg.ClientSecret)
-	}
-	if cfg.ExtraClaims != "" {
-		data.Set(extraClaimsFormKey, cfg.ExtraClaims)
-	}
+	cfg.setClientSecret(data)
+	cfg.setExtraClaims(data)
 
 	tokenResp, err := doTokenExchange(ctx, cfg, cfg.Endpoints.TokenURL, data, nil)
 	if err != nil {
diff --git a/device_flow.go b/device_flow.go
index 8df2035..312657a 100644
--- a/device_flow.go
+++ b/device_flow.go
@@ -70,7 +70,7 @@ func requestDeviceCode(ctx context.Context, cfg *AppConfig) (*oauth2.DeviceAuthR
 		UserCode:                deviceResp.UserCode,
 		VerificationURI:         deviceResp.VerificationURI,
 		VerificationURIComplete: deviceResp.VerificationURIComplete,
-		Expiry:                  time.Now().Add(time.Duration(deviceResp.ExpiresIn) * time.Second),
+		Expiry:                  expiryFromNow(deviceResp.ExpiresIn),
 		Interval:                int64(deviceResp.Interval),
 	}, nil
 }
@@ -151,9 +151,7 @@ func exchangeDeviceCode(
 	data.Set("grant_type", "urn:ietf:params:oauth:grant-type:device_code")
 	data.Set("device_code", deviceCode)
 	data.Set("client_id", cID)
-	if cfg.ExtraClaims != "" {
-		data.Set(extraClaimsFormKey, cfg.ExtraClaims)
-	}
+	cfg.setExtraClaims(data)
 
 	resp, err := cfg.RetryClient.Post(reqCtx, tokenURL,
 		retry.WithBody("application/x-www-form-urlencoded", strings.NewReader(data.Encode())),
@@ -192,7 +190,7 @@ func exchangeDeviceCode(
 		AccessToken:  tokenResp.AccessToken,
 		RefreshToken: tokenResp.RefreshToken,
 		TokenType:    tokenResp.TokenType,
-		Expiry:       time.Now().Add(time.Duration(tokenResp.ExpiresIn) * time.Second),
+		Expiry:       expiryFromNow(tokenResp.ExpiresIn),
 	}, nil
 }
 
diff --git a/token_cmd.go b/token_cmd.go
index cd39457..31049c9 100644
--- a/token_cmd.go
+++ b/token_cmd.go
@@ -285,9 +285,7 @@ func doRevoke(
 	if tokenTypeHint != "" {
 		data.Set("token_type_hint", tokenTypeHint)
 	}
-	if !cfg.IsPublicClient() {
-		data.Set("client_secret", cfg.ClientSecret)
-	}
+	cfg.setClientSecret(data)
 	resp, err := cfg.RetryClient.Post(ctx, revokeURL,
 		retry.WithBody(
 			"application/x-www-form-urlencoded",
diff --git a/tokens.go b/tokens.go
index 060fa70..3a92596 100644
--- a/tokens.go
+++ b/tokens.go
@@ -125,13 +125,34 @@ func doTokenExchange(
 	return &tokenResp, nil
 }
 
+// expiryFromNow returns the absolute expiry time for a token that the server
+// says expires in expiresIn seconds from now.
+func expiryFromNow(expiresIn int) time.Time {
+	return time.Now().Add(time.Duration(expiresIn) * time.Second)
+}
+
+// setClientSecret adds the client_secret form parameter for confidential
+// clients. Public (PKCE) clients omit it.
+func (c *AppConfig) setClientSecret(data url.Values) {
+	if !c.IsPublicClient() {
+		data.Set("client_secret", c.ClientSecret)
+	}
+}
+
+// setExtraClaims adds the extra_claims form parameter when configured.
+func (c *AppConfig) setExtraClaims(data url.Values) {
+	if c.ExtraClaims != "" {
+		data.Set(extraClaimsFormKey, c.ExtraClaims)
+	}
+}
+
 // tokenResponseToCredstore converts a tokenResponse to a credstore.Token.
 func tokenResponseToCredstore(cfg *AppConfig, tr *tokenResponse) *credstore.Token {
 	return &credstore.Token{
 		AccessToken:  tr.AccessToken,
 		RefreshToken: tr.RefreshToken,
 		TokenType:    tr.TokenType,
-		ExpiresAt:    time.Now().Add(time.Duration(tr.ExpiresIn) * time.Second),
+		ExpiresAt:    expiryFromNow(tr.ExpiresIn),
 		ClientID:     cfg.ClientID,
 	}
 }
diff --git a/tui/flow_renderer.go b/tui/flow_renderer.go
index 33b31f2..dd511b4 100644
--- a/tui/flow_renderer.go
+++ b/tui/flow_renderer.go
@@ -21,8 +21,7 @@ type FlowRenderer struct {
 	spinnerFrame                  int
 	spinnerChars                  []rune
 	contentDirty                  bool      // Flag to indicate if content needs redraw
-	inProgressStepIdx             int       // Index of the in-progress step for spinner updates
-	hasInProgressStep             bool      // Whether there's a step in progress
+	inProgressStepIdx             int       // Index of the in-progress step for spinner updates, or -1 if none
 	deviceUserCode                string    // Device code to display
 	deviceVerificationURI         string    // Device verification URL
 	deviceVerificationURIComplete string    // Complete URL with user code
@@ -41,9 +40,10 @@ func NewFlowRenderer(flowType, clientMode, serverURL string) *FlowRenderer {
 	model.height = height
 
 	return &FlowRenderer{
-		model:        model,
-		spinnerFrame: 0,
-		spinnerChars: []rune{'⠋', '⠙', '⠹', '⠸', '⠼', '⠴', '⠦', '⠧', '⠇', '⠏'},
+		model:             model,
+		spinnerFrame:      0,
+		spinnerChars:      []rune{'⠋', '⠙', '⠹', '⠸', '⠼', '⠴', '⠦', '⠧', '⠇', '⠏'},
+		inProgressStepIdx: -1,
 	}
 }
 
@@ -65,10 +65,9 @@ func (r *FlowRenderer) UpdateStep(index int, status FlowStepStatus, message stri
 
 	// Track if this step is in progress for spinner animation
 	if status == StepInProgress {
-		r.hasInProgressStep = true
 		r.inProgressStepIdx = index
 	} else if r.inProgressStepIdx == index {
-		r.hasInProgressStep = false
+		r.inProgressStepIdx = -1
 	}
 }
 
@@ -146,7 +145,7 @@ func (r *FlowRenderer) UpdateDisplay() {
 	resized := r.checkResize()
 
 	// If only spinner changed (not content), do a minimal update
-	if !r.contentDirty && r.hasInProgressStep {
+	if !r.contentDirty && r.inProgressStepIdx >= 0 {
 		r.updateSpinnerOnly()
 		return
 	}
@@ -198,7 +197,7 @@ func (r *FlowRenderer) UpdateDisplay() {
 
 // updateSpinnerOnly updates only the spinner character without redrawing everything
 func (r *FlowRenderer) updateSpinnerOnly() {
-	if !r.hasInProgressStep {
+	if r.inProgressStepIdx < 0 {
 		return
 	}