diff --git a/internal/runtime/executor/claude_executor_request.go b/internal/runtime/executor/claude_executor_request.go
index 8b0838ec6..d330f337c 100644
--- a/internal/runtime/executor/claude_executor_request.go
+++ b/internal/runtime/executor/claude_executor_request.go
@@ -135,7 +135,7 @@ func isManagedClaudeBeta(beta string) bool {
 //	11 advanced-tool-use-2025-11-20       requests using tool search or another advanced tool-use feature
 //	12 effort-2025-11-24                  effort-supporting models with active thinking
 //	13 server-side-fallback-2026-06-01    requests with fallbacks or requested
-//	14 fallback-credit-2026-06-01         OAuth credentials
+//	14 fallback-credit-2026-06-01         requests with fallback tokens, fallbacks, or requested
 //	15 structured-outputs-2025-12-15      structured output requests
 //	16 thinking-display-updates-2026-08-18 requests with thinking.display=updates
 //	17 fast-mode-2026-02-01               speed:fast requests only
@@ -177,7 +177,10 @@ func claudeCodeCLIBetas(body []byte, requested map[string]bool, oauthToken bool)
 	if !isProbeOrHelper && (requested[claudeServerSideFallbackBeta] || gjson.GetBytes(body, "fallbacks").Exists()) {
 		betas = append(betas, claudeServerSideFallbackBeta)
 	}
-	if requested[claudeFallbackCreditBeta] || oauthToken {
+	shouldIncludeFallbackCredit := requested[claudeFallbackCreditBeta] ||
+		gjson.GetBytes(body, "fallback_credit_token").Exists() ||
+		(oauthToken && gjson.GetBytes(body, "fallbacks").Exists())
+	if shouldIncludeFallbackCredit {
 		betas = append(betas, claudeFallbackCreditBeta)
 	}
 	for _, beta := range claudeCodeTrailingBetas {
diff --git a/internal/runtime/executor/claude_executor_test.go b/internal/runtime/executor/claude_executor_test.go
index 3924d91f9..2cae16f29 100644
--- a/internal/runtime/executor/claude_executor_test.go
+++ b/internal/runtime/executor/claude_executor_test.go
@@ -7990,8 +7990,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,advanced-tool-use-2025-11-20," +
-				"effort-2025-11-24,fallback-credit-2026-06-01," +
-				"extended-cache-ttl-2025-04-11",
+				"effort-2025-11-24,extended-cache-ttl-2025-04-11",
 		},
 		{
 			name:  "oauth precedes context-1m",
@@ -8122,7 +8121,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"advisor-tool-2026-03-01,effort-2025-11-24,fallback-credit-2026-06-01," +
+				"advisor-tool-2026-03-01,effort-2025-11-24," +
 				"afk-mode-2026-01-31,extended-cache-ttl-2025-04-11",
 		},
 		{
@@ -8134,7 +8133,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"effort-2025-11-24,fallback-credit-2026-06-01,fast-mode-2026-02-01," +
+				"effort-2025-11-24,fast-mode-2026-02-01," +
 				"afk-mode-2026-01-31,extended-cache-ttl-2025-04-11",
 		},
 		{
@@ -8145,7 +8144,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"effort-2025-11-24,fallback-credit-2026-06-01,extended-cache-ttl-2025-04-11",
+				"effort-2025-11-24,extended-cache-ttl-2025-04-11",
 		},
 		{
 			name: "thinking display updates emits thinking-display-updates beta and drops redact-thinking",
@@ -8168,7 +8167,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"effort-2025-11-24,fallback-credit-2026-06-01",
+				"effort-2025-11-24",
 		},
 		{
 			name:  "probe request max_tokens=1 omits effort and extended-cache-ttl betas",
@@ -8177,8 +8176,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 			want: "claude-code-20250219,oauth-2025-04-20," +
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
-				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"fallback-credit-2026-06-01",
+				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07",
 		},
 		{
 			name:      "haiku model omits effort beta even if requested",
@@ -8189,7 +8187,7 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05," +
-				"fallback-credit-2026-06-01,extended-cache-ttl-2025-04-11",
+				"extended-cache-ttl-2025-04-11",
 		},
 		{
 			name:      "disabled thinking omits effort beta even if requested",
@@ -8200,7 +8198,39 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
 				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
 				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
-				"fallback-credit-2026-06-01,extended-cache-ttl-2025-04-11",
+				"extended-cache-ttl-2025-04-11",
+		},
+		{
+			name:  "body with fallback_credit_token automatically adds fallback-credit beta",
+			body:  `{"model":"claude-sonnet-5","fallback_credit_token":"fct_12345"}`,
+			oauth: true,
+			want: "claude-code-20250219,oauth-2025-04-20," +
+				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
+				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
+				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
+				"effort-2025-11-24,fallback-credit-2026-06-01,extended-cache-ttl-2025-04-11",
+		},
+		{
+			name:  "oauth body with fallbacks automatically adds fallback-credit beta",
+			body:  `{"model":"claude-fable-5-1","fallbacks":[{"model":"claude-opus-5"}]}`,
+			oauth: true,
+			want: "claude-code-20250219,oauth-2025-04-20," +
+				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
+				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
+				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
+				"effort-2025-11-24,server-side-fallback-2026-06-01,fallback-credit-2026-06-01," +
+				"extended-cache-ttl-2025-04-11",
+		},
+		{
+			name:      "requested fallback-credit beta is honored",
+			body:      `{"model":"claude-sonnet-5"}`,
+			requested: map[string]bool{claudeFallbackCreditBeta: true},
+			oauth:     true,
+			want: "claude-code-20250219,oauth-2025-04-20," +
+				"interleaved-thinking-2025-05-14,redact-thinking-2026-02-12," +
+				"thinking-token-count-2026-05-13,context-management-2025-06-27," +
+				"prompt-caching-scope-2026-01-05,mid-conversation-system-2026-04-07," +
+				"effort-2025-11-24,fallback-credit-2026-06-01,extended-cache-ttl-2025-04-11",
 		},
 	}
 
diff --git a/internal/runtime/executor/claude_fingerprint_policy_test.go b/internal/runtime/executor/claude_fingerprint_policy_test.go
index 4fe9c990a..0e86482da 100644
--- a/internal/runtime/executor/claude_fingerprint_policy_test.go
+++ b/internal/runtime/executor/claude_fingerprint_policy_test.go
@@ -235,7 +235,8 @@ func TestApplyClaudeHeaders_ClaudeCodeCLIProfileUsesOAuthBetasWithoutPretendingT
 	if errReq != nil {
 		t.Fatalf("NewRequest() error = %v", errReq)
 	}
-	if errHeaders := applyClaudeHeaders(req, auth, "key-third-party", false, nil, []byte(`{"model":"claude-sonnet-5"}`), &config.Config{}, nil, false, "11111111-2222-4333-8444-555555555555"); errHeaders != nil {
+	payload := []byte(`{"model":"claude-sonnet-5"}`)
+	if errHeaders := applyClaudeHeaders(req, auth, "key-third-party", false, nil, payload, &config.Config{}, nil, false, "11111111-2222-4333-8444-555555555555"); errHeaders != nil {
 		t.Fatalf("applyClaudeHeaders() error = %v", errHeaders)
 	}
 	if got := req.Header.Get("Authorization"); got != "Bearer key-third-party" {
@@ -245,14 +246,8 @@ func TestApplyClaudeHeaders_ClaudeCodeCLIProfileUsesOAuthBetasWithoutPretendingT
 		t.Fatalf("x-api-key = %q, want empty on third-party gateway", got)
 	}
 	betas := req.Header.Get("Anthropic-Beta")
-	if !strings.Contains(betas, "oauth-2025-04-20") {
-		t.Fatalf("Anthropic-Beta = %q, want oauth beta", betas)
-	}
-	if !strings.Contains(betas, "extended-cache-ttl-2025-04-11") {
-		t.Fatalf("Anthropic-Beta = %q, want extended-cache-ttl", betas)
-	}
-	if !strings.Contains(betas, "fallback-credit-2026-06-01") {
-		t.Fatalf("Anthropic-Beta = %q, want fallback-credit", betas)
+	if want := claudeCodeCLIBetas(payload, nil, true); betas != want {
+		t.Fatalf("Anthropic-Beta = %q, want %q", betas, want)
 	}
 }