fix: exclude expanded tools from prompt diffs

internal/sync/api/catalog.go

@@ -156,7 +156,9 @@ func (config *Config) UnmarshalJSON(data []byte) error {
 	config.Variations = make([]syncdomain.Variation, 0, len(response.Variations))
 	for _, variation := range response.Variations {
 		if variation.State != "archived" {
-			config.Variations = append(config.Variations, variation.Variation)
+			canonical := variation.Variation
+			canonical.Model = syncdomain.CanonicalModel(canonical.Model, canonical.Tools)
+			config.Variations = append(config.Variations, canonical)
 		}
 	}
 	return nil

internal/sync/api/catalog_test.go

@@ -167,6 +167,41 @@ func TestCatalogClientConfigGetsExactConfigAndAppliesMode(t *testing.T) {
 	assert.False(t, request.IsBeta)
 }
 
+func TestCatalogClientConfigRemovesExpandedToolsFromModelParameters(t *testing.T) {
+	transport := &recordingClient{Responses: [][]byte{[]byte(`{
+		"key": "support",
+		"mode": "agent",
+		"variations": [{
+			"key": "helpful",
+			"name": "Helpful",
+			"model": {
+				"modelName": "claude",
+				"parameters": {
+					"temperature": 0.2,
+					"tools": [{"type": "function", "name": "search"}],
+					"skills": [{"key": "support"}]
+				}
+			},
+			"tools": [{"key": "search", "version": 3}],
+			"skills": [{"key": "support", "version": 2}]
+		}]
+	}`)}}
+
+	config, err := NewClient(transport, "token", "https://example.com").Config("project", "support")
+
+	require.NoError(t, err)
+	require.Len(t, config.Variations, 1)
+	assert.Equal(t, map[string]any{
+		"modelName": "claude",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+			"skills":      []any{map[string]any{"key": "support"}},
+		},
+	}, config.Variations[0].Model)
+	assert.Equal(t, []syncdomain.AttachmentRef{{Key: "search", Version: 3}}, config.Variations[0].Tools)
+	assert.Equal(t, []syncdomain.AttachmentRef{{Key: "support", Version: 2}}, config.Variations[0].Skills)
+}
+
 func TestCatalogClientConfigRejectsInvalidResponse(t *testing.T) {
 	client := NewClient(
 		&recordingClient{Responses: [][]byte{[]byte(`not json`)}},

internal/sync/fingerprint.go

@@ -76,7 +76,7 @@ func (variation Variation) canonical() Variation {
 		variation.Attachments[index] = CanonicalAttachment(variation.Attachments[index])
 	}
 	variation.SortAttachments()
-	variation.Model = canonicalModel(variation.Model)
+	variation.Model = CanonicalModel(variation.Model, variation.Tools)
 
 	switch variation.Mode {
 	case VariationModeAgent:
@@ -108,14 +108,23 @@ func unversionedRefs(refs []AttachmentRef) []AttachmentRef {
 	return unversioned
 }
 
-// canonicalModel removes the empty "parameters" and "custom" objects that the
-// variation API adds. Other empty objects can change behavior, so they remain.
-func canonicalModel(model map[string]any) map[string]any {
+// CanonicalModel returns a copy without defaults and expanded tool content
+// that the variation API adds. Tool references own that content.
+func CanonicalModel(model map[string]any, tools []AttachmentRef) map[string]any {
 	model = maps.Clone(model)
-	for _, key := range []string{"parameters", "custom"} {
-		if value, ok := model[key].(map[string]any); ok && len(value) == 0 {
-			delete(model, key)
+	if parameters, ok := model["parameters"].(map[string]any); ok {
+		parameters = maps.Clone(parameters)
+		if len(tools) != 0 {
+			delete(parameters, "tools")
 		}
+		if len(parameters) == 0 {
+			delete(model, "parameters")
+		} else {
+			model["parameters"] = parameters
+		}
+	}
+	if custom, ok := model["custom"].(map[string]any); ok && len(custom) == 0 {
+		delete(model, "custom")
 	}
 	if len(model) == 0 {
 		return nil

internal/sync/fingerprint_test.go

@@ -137,6 +137,64 @@ func TestFingerprintVariationNormalizesModelDefaults(t *testing.T) {
 	require.Contains(t, withDefaults.Model, "custom")
 }
 
+func TestFingerprintVariationExcludesExpandedToolParameters(t *testing.T) {
+	base := Variation{
+		Mode: VariationModeAgent,
+		Key:  "agent",
+		Name: "Agent",
+		Model: map[string]any{
+			"modelName": "claude",
+			"parameters": map[string]any{
+				"temperature": 0.2,
+			},
+		},
+		Tools: []AttachmentRef{{Key: "search"}},
+	}
+	expanded := base
+	expanded.Model = map[string]any{
+		"modelName": "claude",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+			"tools":       []any{map[string]any{"type": "function", "name": "search"}},
+		},
+	}
+	changed := expanded
+	changed.Model = map[string]any{
+		"modelName": "claude",
+		"parameters": map[string]any{
+			"temperature": 0.7,
+			"tools":       []any{map[string]any{"type": "function", "name": "search"}},
+		},
+	}
+
+	baseFingerprint, err := FingerprintVariation("project", "config/agent", base)
+	require.NoError(t, err)
+	expandedFingerprint, err := FingerprintVariation("project", "config/agent", expanded)
+	require.NoError(t, err)
+	changedFingerprint, err := FingerprintVariation("project", "config/agent", changed)
+	require.NoError(t, err)
+
+	require.Equal(t, baseFingerprint, expandedFingerprint)
+	require.NotEqual(t, baseFingerprint, changedFingerprint)
+	require.Contains(t, expanded.Model["parameters"], "tools")
+
+	withoutSkillParameter := base
+	withoutSkillParameter.Skills = []AttachmentRef{{Key: "support"}}
+	withSkillParameter := withoutSkillParameter
+	withSkillParameter.Model = map[string]any{
+		"modelName": "claude",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+			"skills":      []any{map[string]any{"key": "support"}},
+		},
+	}
+	withoutSkillFingerprint, err := FingerprintVariation("project", "config/agent", withoutSkillParameter)
+	require.NoError(t, err)
+	withSkillFingerprint, err := FingerprintVariation("project", "config/agent", withSkillParameter)
+	require.NoError(t, err)
+	require.NotEqual(t, withoutSkillFingerprint, withSkillFingerprint)
+}
+
 func TestFingerprintVariationPreservesMeaningfulModelChanges(t *testing.T) {
 	base := Variation{
 		Mode: VariationModeAgent,

internal/sync/prompt/acceptance_test.go

@@ -272,6 +272,73 @@ func TestPromptFirstSyncAdoptsMatchingStateWithoutMutation(t *testing.T) {
 	requireOnlyReads(t, api.requests)
 }
 
+func TestPromptDiffExcludesExpandedToolsFromModelParameters(t *testing.T) {
+	root := initRepository(t)
+	description := "Search the documentation"
+	tool := syncdomain.Tool{
+		Key:         "search",
+		Description: &description,
+		Schema:      map[string]any{"type": "object"},
+	}
+	local := variation("Support")
+	local.Instructions = "Use the local instructions."
+	local.ModelConfigKey = "claude"
+	local.ModelConfigVersion = 2
+	local.Model = map[string]any{
+		"modelName": "claude-sonnet-4",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+		},
+	}
+	local.Tools = []syncdomain.AttachmentRef{{Key: "search", Version: 3}}
+	local.Attachments = []syncdomain.Attachment{toolAttachment(tool, 3)}
+	writeVariation(t, root, local, false)
+	writeManifest(t, root, local)
+
+	server := local
+	server.Instructions = "Use the LaunchDarkly instructions."
+	server.Attachments = nil
+	server.Model = map[string]any{
+		"modelName": "claude-sonnet-4",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+			"tools": []any{map[string]any{
+				"type":        "function",
+				"name":        "search",
+				"description": description,
+				"parameters":  map[string]any{"type": "object"},
+			}},
+		},
+	}
+	api := &directAPI{
+		variation: &server,
+		tools: map[string]versionedTool{
+			"search": {Tool: tool, Version: 3},
+		},
+	}
+
+	stdout, _, err := runPrompt(t, root, api, "--dry-run", "--diff", "--output", "plaintext")
+
+	require.NoError(t, err)
+	assert.Contains(t, stdout, "instructions changed in LaunchDarkly")
+	assert.NotContains(t, stdout, "model changed in LaunchDarkly")
+	assert.NotContains(t, stdout, `"type": "function"`)
+	assert.NotContains(t, stdout, `Tool "search"`)
+
+	_, _, err = runPrompt(t, root, api, "--yes")
+	require.NoError(t, err)
+	resources, err := synclocal.CompileWorkspace(root)
+	require.NoError(t, err)
+	require.Len(t, resources, 1)
+	assert.Equal(t, map[string]any{
+		"modelName": "claude-sonnet-4",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+		},
+	}, resources[0].Variation.Model)
+	assert.Equal(t, []syncdomain.AttachmentRef{{Key: "search"}}, resources[0].Variation.Tools)
+}
+
 func TestPromptFirstSyncCreatesUpsertVariation(t *testing.T) {
 	root := initRepository(t)
 	local := variation("New")

internal/sync/prompt/diff.go

@@ -73,6 +73,7 @@ func variationJSON(variation *syncdomain.Variation) json.RawMessage {
 		return nil
 	}
 	withoutRefs := *variation
+	withoutRefs.Model = syncdomain.CanonicalModel(withoutRefs.Model, withoutRefs.Tools)
 	withoutRefs.Tools, withoutRefs.Skills = nil, nil
 	data, _ := json.Marshal(withoutRefs)
 	return data

internal/sync/prompt/plan_test.go

@@ -124,6 +124,37 @@ func TestBuildPlanOmitsDiffForEquivalentAPIDefaults(t *testing.T) {
 	require.Empty(t, plan.Resources[0].Diff)
 }
 
+func TestBuildPlanKeepsRealModelParameterChangesWithExpandedTools(t *testing.T) {
+	local := testVariation("example")
+	local.Tools = []syncdomain.AttachmentRef{{Key: "search"}}
+	local.Model = map[string]any{
+		"modelName": "gpt-5",
+		"parameters": map[string]any{
+			"temperature": 0.2,
+		},
+	}
+	server := local
+	server.Model = map[string]any{
+		"modelName": "gpt-5",
+		"parameters": map[string]any{
+			"temperature": 0.7,
+			"tools":       []any{map[string]any{"type": "function", "name": "search"}},
+		},
+	}
+
+	id := testResourceID()
+	manifest := syncmanifest.New()
+	manifest.SetFingerprint(id, fingerprintOf(t, local))
+	plan := BuildPlan(manifest, localResources(&local, false), map[ResourceID]ServerResource{
+		id: {Variation: &server, ConfigMode: syncdomain.VariationModeAgent},
+	})
+
+	require.Equal(t, ActionUpdateLocal, plan.Resources[0].Action)
+	require.Equal(t, "model changed in LaunchDarkly", planReason(plan.Resources[0]))
+	require.NotContains(t, string(plan.Resources[0].Diff["variation"].Before), `"tools"`)
+	require.Contains(t, string(plan.Resources[0].Diff["variation"].Before), `"temperature":0.7`)
+}
+
 func TestBuildPlanRejectsParentConfigModeMismatch(t *testing.T) {
 	local := testVariation("local")
 	id := testResourceID()