fix(claude): distinguish claude-sonnet-5-5 from sonnet-5 in model checks

- Add `isClaudeSonnet55Model` helper and prevent Sonnet 5 matching on Sonnet 5.5 prefixes
- Include Claude Sonnet 5.5 in progress display checks

Closes: #6193

internal/runtime/executor/claude_executor_request.go

@@ -302,15 +302,23 @@ func isClaudeOpus55Model(model string) bool {
 	return model == "claude-opus-5-5" || strings.HasPrefix(model, "claude-opus-5-5[")
 }
 
+func isClaudeSonnet55Model(model string) bool {
+	model = claudeCanonicalModel(model)
+	return model == "claude-sonnet-5-5" || strings.HasPrefix(model, "claude-sonnet-5-5-") || strings.HasPrefix(model, "claude-sonnet-5-5[")
+}
+
 func isClaudeSonnet5Model(model string) bool {
 	model = claudeCanonicalModel(model)
+	if isClaudeSonnet55Model(model) {
+		return false
+	}
 	return model == "claude-sonnet-5" || strings.HasPrefix(model, "claude-sonnet-5-") || strings.HasPrefix(model, "claude-sonnet-5[")
 }
 
 // claudeModelUsesProgressDisplay reports the 2.1.280 interactive CLI models that
 // send thinking.display=updates unless the caller already chose a display mode.
 func claudeModelUsesProgressDisplay(model string) bool {
-	return isClaudeOpus55Model(model) || isClaudeFable51Model(model) || isClaudeSonnet5Model(model)
+	return isClaudeOpus55Model(model) || isClaudeFable51Model(model) || isClaudeSonnet5Model(model) || isClaudeSonnet55Model(model)
 }
 
 // applyClaudeCloakThinkingDisplay fills the latest CLI display only when the

internal/runtime/executor/claude_executor_test.go

@@ -8139,6 +8139,11 @@ func TestClaudeCodeCLIBetas_MatchesObservedClientMatrix(t *testing.T) {
 			body: `{"model":"claude-sonnet-5"}`,
 			want: constants + ",mid-conversation-system-2026-04-07,mid-conversation-system-clear-at-2026-08-21,effort-2025-11-24",
 		},
+		{
+			name: "claude-sonnet-5-5 carries tool changes beta unlike sonnet-5",
+			body: `{"model":"claude-sonnet-5-5"}`,
+			want: constants + ",mid-conversation-system-2026-04-07,mid-conversation-tool-changes-2026-07-01,mid-conversation-system-clear-at-2026-08-21,effort-2025-11-24",
+		},
 		{
 			name: "claude-opus-4-8 accepts role=system",
 			body: `{"model":"claude-opus-4-8"}`,

internal/runtime/executor/claude_issue_6193_test.go

@@ -0,0 +1,107 @@
+package executor
+
+import (
+	"bytes"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v8/internal/config"
+	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v8/sdk/cliproxy/auth"
+)
+
+// TestIssue6193_Sonnet55ToolChangeBeta verifies that Sonnet 5.5 receives the
+// mid-conversation-tool-changes-2026-07-01 beta, while Sonnet 5 remains excluded,
+// and that on the Claude OAuth / CLI-fingerprint path the beta reaches Anthropic.
+func TestIssue6193_Sonnet55ToolChangeBeta(t *testing.T) {
+	// 1. In claudeCodeCLIBetas, Sonnet 5.5 (and dated/bracket variants) must include
+	// mid-conversation-tool-changes-2026-07-01, while Sonnet 5 must remain excluded.
+	sonnet55Variants := []string{
+		"claude-sonnet-5-5",
+		"claude-sonnet-5-5-20261001",
+		"claude-sonnet-5-5[1m]",
+	}
+	for _, model := range sonnet55Variants {
+		betas := claudeCodeCLIBetas([]byte(`{"model":"`+model+`"}`), nil, false)
+		if !strings.Contains(betas, "mid-conversation-tool-changes-2026-07-01") {
+			t.Fatalf("claudeCodeCLIBetas for %s missing mid-conversation-tool-changes-2026-07-01, got: %s", model, betas)
+		}
+		if isClaudeSonnet5Model(model) {
+			t.Fatalf("isClaudeSonnet5Model(%q) = true, want false", model)
+		}
+		if !isClaudeSonnet55Model(model) {
+			t.Fatalf("isClaudeSonnet55Model(%q) = false, want true", model)
+		}
+		if !claudeModelUsesProgressDisplay(model) {
+			t.Fatalf("claudeModelUsesProgressDisplay(%q) = false, want true", model)
+		}
+	}
+
+	sonnet5Variants := []string{
+		"claude-sonnet-5",
+		"claude-sonnet-5-20260401",
+		"claude-sonnet-5[1m]",
+	}
+	for _, model := range sonnet5Variants {
+		betas := claudeCodeCLIBetas([]byte(`{"model":"`+model+`"}`), nil, false)
+		if strings.Contains(betas, "mid-conversation-tool-changes-2026-07-01") {
+			t.Fatalf("claudeCodeCLIBetas for %s unexpectedly includes mid-conversation-tool-changes-2026-07-01, got: %s", model, betas)
+		}
+		if !isClaudeSonnet5Model(model) {
+			t.Fatalf("isClaudeSonnet5Model(%q) = false, want true", model)
+		}
+		if isClaudeSonnet55Model(model) {
+			t.Fatalf("isClaudeSonnet55Model(%q) = true, want false", model)
+		}
+		if !claudeModelUsesProgressDisplay(model) {
+			t.Fatalf("claudeModelUsesProgressDisplay(%q) = false, want true", model)
+		}
+	}
+
+	// 2. Outgoing Anthropic-Beta on Claude OAuth / CLI fingerprint path for claude-sonnet-5-5
+	// must contain mid-conversation-tool-changes-2026-07-01, both when caller sends an explicit beta
+	// and when caller sends no client beta.
+	body := []byte(`{
+		"model": "claude-sonnet-5-5",
+		"max_tokens": 64,
+		"tools": [{"name":"lookup_notes","input_schema":{"type":"object"}}],
+		"messages": [
+			{"role":"user","content":"hello"},
+			{"role":"system","content":[{"type":"tool_removal","tool":{"type":"tool_reference","name":"lookup_notes"}}]}
+		]
+	}`)
+
+	auth := &cliproxyauth.Auth{
+		ID:       "test-oauth",
+		Metadata: map[string]any{"access_token": "sk-ant-oat-issue-6193"},
+	}
+
+	for _, tc := range []struct {
+		name        string
+		clientBetas string
+	}{
+		{name: "with explicit legacy beta", clientBetas: "mid-conversation-tool-changes-2026-07-01"},
+		{name: "without client beta", clientBetas: ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			incomingHeaders := http.Header{}
+			if tc.clientBetas != "" {
+				incomingHeaders.Set("Anthropic-Beta", tc.clientBetas)
+			}
+
+			req, err := http.NewRequest(http.MethodPost, "https://api.anthropic.com/v1/messages", bytes.NewReader(body))
+			if err != nil {
+				t.Fatalf("http.NewRequest failed: %v", err)
+			}
+
+			if errApply := applyClaudeHeaders(req, auth, "sk-ant-oat-issue-6193", false, nil, body, &config.Config{}, incomingHeaders, false); errApply != nil {
+				t.Fatalf("applyClaudeHeaders failed: %v", errApply)
+			}
+
+			upstreamBetas := req.Header.Get("Anthropic-Beta")
+			if !strings.Contains(upstreamBetas, "mid-conversation-tool-changes-2026-07-01") {
+				t.Fatalf("applyClaudeHeaders for claude-sonnet-5-5 missing mid-conversation-tool-changes-2026-07-01, got Anthropic-Beta: %s", upstreamBetas)
+			}
+		})
+	}
+}