feat: add option to disable on-device AI model download

README.md

@@ -5,7 +5,7 @@
 English | [中文](docs/README.zh.md)
 
 `go-chrome-ai` is a cross-platform Chrome profile patcher written in Go, with both **CLI** and **GUI** modes.
-It helps enable Chrome AI-related features, including **Ask Gemini**, without reinstalling Chrome or recreating your profile.
+It helps enable Chrome AI-related features (including **Ask Gemini**) without reinstalling Chrome or recreating your profile, and can also **block Chrome from silently downloading the on-device Gemini Nano model** (~2–4 GB) by flipping the relevant `chrome://flags` and applying Google's [`GenAILocalFoundationalModelSettings`](https://chromeenterprise.google/policies/gen-ai-local-foundational-model-settings/) Enterprise policy.
 
 ![go-chrome-ai social preview](docs/images/social-preview.png)
 
@@ -67,6 +67,17 @@ It enables Chrome AI-related features (such as **Ask Gemini**) by patching local
 - `variations_country` -> `"us"`
 - `variations_permanent_consistency_country` -> `["<last_version>", "us"]` (if field exists and is patchable)
 
+It can also **block on-device AI model downloads** (Gemini Nano), which is the default in both CLI and GUI. The block applies three changes:
+
+- `chrome://flags/#optimization-guide-on-device-model` -> Disabled
+- `chrome://flags/#prompt-api-for-gemini-nano` -> Disabled
+- `GenAILocalFoundationalModelSettings = 1` written to the OS managed-policy store
+  - macOS: `defaults write com.google.Chrome GenAILocalFoundationalModelSettings -int 1`
+  - Linux: `/etc/opt/chrome/policies/managed/go-chrome-ai.json` (needs sudo)
+  - Windows: `HKLM\Software\Policies\Google\Chrome` REG_DWORD
+
+Because the third change is an Enterprise policy, Chrome will display the "managed by your organization" banner afterwards. Pass `-disable-ai-download=false` (CLI) or untick the option (GUI) if you do not want that.
+
 ## Screenshot
 
 ![go-chrome-ai GUI](docs/images/go-chrome-ai-gui.png)
@@ -86,6 +97,7 @@ Flags:
 
 - `-dry-run`: show changes without writing files or killing Chrome
 - `-no-restart`: patch but do not restart Chrome
+- `-disable-ai-download` (default `true`): block on-device AI model downloads by disabling the relevant `chrome://flags` entries and writing `GenAILocalFoundationalModelSettings=1` to the OS managed-policy store. Use `-disable-ai-download=false` to skip.
 
 ## Run GUI
 
@@ -98,9 +110,11 @@ Prebuilt Linux and Windows releases are CLI-only. Build from source if you want
 The GUI includes:
 
 - auto-detection of installed Chrome channels
+- left/right split layout (configuration on the left, run controls + logs on the right)
 - one-click patch flow
 - progress bar
 - real-time logs
+- a "Disable on-device AI model download" toggle that previews the exact `chrome://flags` and `chrome://policy` changes before you press Run
 
 ## Build From Source
 

docs/README.zh.md

@@ -3,7 +3,7 @@
 [English](../README.md) | 中文
 
 `go-chrome-ai` 是一个用 Go 编写的跨平台 Chrome 配置修补工具，同时支持 **CLI** 和 **GUI**。
-它可以在不重装 Chrome、不重建用户配置的情况下启用相关 AI 功能（包括 **Ask Gemini**）。
+它可以在不重装 Chrome、不重建用户配置的情况下启用相关 AI 功能（包括 **Ask Gemini**），也可以通过翻转相关的 `chrome://flags` 配合 Google 官方的 [`GenAILocalFoundationalModelSettings`](https://chromeenterprise.google/policies/gen-ai-local-foundational-model-settings/) 企业策略，**阻止 Chrome 静默下载 Gemini Nano 本地大模型**（约 2–4 GB）。
 
 ![go-chrome-ai social preview](images/social-preview.png)
 
@@ -65,6 +65,17 @@ xattr -d com.apple.quarantine $(which go-chrome-ai)
 - 将 `variations_country` 设为 `"us"`
 - 将 `variations_permanent_consistency_country` 设为 `["<last_version>", "us"]`（仅当该字段存在且可修改）
 
+同时还可以**阻止 Chrome 下载本地 AI 模型**（Gemini Nano），CLI 与 GUI 都默认开启。该行为会做三件事：
+
+- `chrome://flags/#optimization-guide-on-device-model` -> Disabled
+- `chrome://flags/#prompt-api-for-gemini-nano` -> Disabled
+- `GenAILocalFoundationalModelSettings = 1` 写入系统受管策略存储
+  - macOS：`defaults write com.google.Chrome GenAILocalFoundationalModelSettings -int 1`
+  - Linux：`/etc/opt/chrome/policies/managed/go-chrome-ai.json`（需要 sudo）
+  - Windows：`HKLM\Software\Policies\Google\Chrome` REG_DWORD
+
+第三步属于企业策略，Chrome 之后会显示「由贵组织管理」横幅。如果你不希望出现该横幅，可以在 CLI 中加 `-disable-ai-download=false`，或在 GUI 中取消勾选该选项。
+
 ## 截图
 
 ![go-chrome-ai GUI](images/go-chrome-ai-gui.png)
@@ -84,6 +95,7 @@ go run ./cmd/go-chrome-ai
 
 - `-dry-run`：只显示将修改的内容，不写入文件，也不关闭 Chrome
 - `-no-restart`：修补后不重启 Chrome
+- `-disable-ai-download`（默认 `true`）：阻止本地 AI 模型下载——禁用相关的 `chrome://flags` 并向系统受管策略存储写入 `GenAILocalFoundationalModelSettings=1`。使用 `-disable-ai-download=false` 可跳过
 
 ## 运行 GUI
 
@@ -96,9 +108,11 @@ Linux 和 Windows 的预编译发布包默认只包含 CLI；如果需要 Fyne G
 GUI 功能：
 
 - 自动检测已安装的 Chrome 渠道
+- 左右分栏布局（左侧参数配置，右侧执行控件 + 日志）
 - 一键修补
 - 进度条
 - 实时日志
+- 「Disable on-device AI model download」开关，会在执行前预览将要应用到 `chrome://flags` 与 `chrome://policy` 的具体改动
 
 ## 从源码构建
 

internal/app/cli.go

@@ -8,18 +8,23 @@ import (
 	"os"
 
 	"github.com/itamaker/go-chrome-ai/internal/chrome"
+	"github.com/itamaker/go-chrome-ai/internal/meta"
 )
 
 func RunCLI(args []string, stderr io.Writer) int {
 	if stderr == nil {
 		stderr = os.Stderr
 	}
 
+	fmt.Println("go-chrome-ai -", meta.RepoURL)
+
 	fs := flag.NewFlagSet("go-chrome-ai", flag.ContinueOnError)
 	fs.SetOutput(stderr)
 
 	dryRun := fs.Bool("dry-run", false, "Show what would change without modifying files")
 	noRestart := fs.Bool("no-restart", false, "Do not restart Chrome after patching")
+	disableAI := fs.Bool("disable-ai-download", true,
+		"Block on-device Gemini Nano download (use -disable-ai-download=false to skip)")
 
 	if err := fs.Parse(args); err != nil {
 		if errors.Is(err, flag.ErrHelp) {
@@ -28,9 +33,34 @@ func RunCLI(args []string, stderr io.Writer) int {
 		return 2
 	}
 
+	if *disableAI {
+		fmt.Println("Disable AI model download - will apply:")
+		fmt.Println("  Local flag overrides (chrome://flags):")
+		for _, action := range chrome.DisableAIDownloadActions() {
+			if action.EnterprisePolicy {
+				continue
+			}
+			fmt.Println("    - " + action.Label)
+		}
+		fmt.Println("  Enterprise policy (chrome://policy):")
+		for _, action := range chrome.DisableAIDownloadActions() {
+			if !action.EnterprisePolicy {
+				continue
+			}
+			fmt.Println("    - " + action.Label)
+			if action.Detail != "" {
+				fmt.Println("      " + action.Detail)
+			}
+			if action.PolicyNote != "" {
+				fmt.Println("      ! " + action.PolicyNote)
+			}
+		}
+	}
+
 	summary, err := chrome.Run(chrome.Options{
-		DryRun:    *dryRun,
-		NoRestart: *noRestart,
+		DryRun:                 *dryRun,
+		NoRestart:              *noRestart,
+		DisableAIModelDownload: *disableAI,
 	}, chrome.Callbacks{
 		Log: func(message string) {
 			fmt.Println(message)

internal/chrome/flags.go

@@ -0,0 +1,105 @@
+package chrome
+
+import "strings"
+
+// Chrome stores flag selections in Local State under
+// `browser.enabled_labs_experiments` as a list of strings of the form
+// `<flag-name>@<choice>` where 0=Default, 1=Enabled, 2=Disabled.
+const flagDisabledSuffix = "@2"
+
+// AIDownloadFlagNames are the chrome://flags entries this tool forces to
+// "Disabled" so Chrome does not download Gemini Nano / on-device models.
+var AIDownloadFlagNames = []string{
+	"optimization-guide-on-device-model",
+	"prompt-api-for-gemini-nano",
+}
+
+// DisableAIDownloadAction describes one transform applied by the
+// "disable AI model download" feature.
+type DisableAIDownloadAction struct {
+	Label            string // human-readable label, e.g. "chrome://flags/#foo -> Disabled"
+	Detail           string // optional second line (e.g. policy storage location)
+	EnterprisePolicy bool   // true if the action writes a managed Chrome policy
+	PolicyNote       string // extra warning shown when EnterprisePolicy is true
+}
+
+// DisableAIDownloadActions returns the ordered list of changes applied when
+// the user enables "disable AI model download". The last entry is an
+// Enterprise policy write that causes Chrome to display the
+// "managed by your organization" banner.
+func DisableAIDownloadActions() []DisableAIDownloadAction {
+	actions := make([]DisableAIDownloadAction, 0, len(AIDownloadFlagNames)+1)
+	for _, name := range AIDownloadFlagNames {
+		actions = append(actions, DisableAIDownloadAction{
+			Label: "chrome://flags/#" + name + " -> Disabled",
+		})
+	}
+	actions = append(actions, DisableAIDownloadAction{
+		Label:            GenAIPolicyName + " = 1 (Disabled)",
+		Detail:           policyStorageDescription(),
+		EnterprisePolicy: true,
+		PolicyNote:       `Chrome will show the "managed by your organization" banner`,
+	})
+	return actions
+}
+
+
+// setFlagsDisabled rewrites browser.enabled_labs_experiments so each requested
+// flag appears exactly once with the Disabled choice (@2). Returns the list
+// of flag names whose state actually changed.
+func setFlagsDisabled(localState map[string]any, flags []string) []string {
+	browser, _ := localState["browser"].(map[string]any)
+	if browser == nil {
+		browser = map[string]any{}
+		localState["browser"] = browser
+	}
+
+	rawList, _ := browser["enabled_labs_experiments"].([]any)
+	existing := make([]string, 0, len(rawList))
+	for _, item := range rawList {
+		if s, ok := item.(string); ok {
+			existing = append(existing, s)
+		}
+	}
+
+	targets := make(map[string]bool, len(flags))
+	for _, name := range flags {
+		targets[name] = true
+	}
+
+	kept := make([]string, 0, len(existing))
+	alreadyDisabled := make(map[string]bool, len(flags))
+	for _, entry := range existing {
+		name := entry
+		if idx := strings.IndexByte(entry, '@'); idx >= 0 {
+			name = entry[:idx]
+		}
+		if targets[name] {
+			if entry == name+flagDisabledSuffix && !alreadyDisabled[name] {
+				alreadyDisabled[name] = true
+				kept = append(kept, entry)
+			}
+			continue
+		}
+		kept = append(kept, entry)
+	}
+
+	changed := make([]string, 0, len(flags))
+	for _, name := range flags {
+		if !alreadyDisabled[name] {
+			kept = append(kept, name+flagDisabledSuffix)
+			changed = append(changed, name)
+		}
+	}
+
+	if len(changed) == 0 && len(kept) == len(existing) {
+		return nil
+	}
+
+	next := make([]any, len(kept))
+	for i, s := range kept {
+		next[i] = s
+	}
+	browser["enabled_labs_experiments"] = next
+	return changed
+}

internal/chrome/flags_test.go

@@ -0,0 +1,94 @@
+package chrome
+
+import (
+	"reflect"
+	"sort"
+	"testing"
+)
+
+func TestSetFlagsDisabled(t *testing.T) {
+	cases := []struct {
+		name      string
+		input     map[string]any
+		flags     []string
+		want      []string
+		wantList  []any
+		wantNil   bool
+	}{
+		{
+			name:  "fresh local state, no browser key",
+			input: map[string]any{},
+			flags: []string{"foo"},
+			want:  []string{"foo"},
+			wantList: []any{"foo@2"},
+		},
+		{
+			name: "flag already disabled is left alone",
+			input: map[string]any{
+				"browser": map[string]any{
+					"enabled_labs_experiments": []any{"foo@2"},
+				},
+			},
+			flags:    []string{"foo"},
+			wantNil:  true,
+			wantList: []any{"foo@2"},
+		},
+		{
+			name: "flag previously enabled is flipped to disabled",
+			input: map[string]any{
+				"browser": map[string]any{
+					"enabled_labs_experiments": []any{"foo@1", "bar"},
+				},
+			},
+			flags:    []string{"foo"},
+			want:     []string{"foo"},
+			wantList: []any{"bar", "foo@2"},
+		},
+		{
+			name: "duplicates are coalesced",
+			input: map[string]any{
+				"browser": map[string]any{
+					"enabled_labs_experiments": []any{"foo@1", "foo@2"},
+				},
+			},
+			flags:    []string{"foo"},
+			wantList: []any{"foo@2"},
+		},
+		{
+			name: "multiple flags",
+			input: map[string]any{
+				"browser": map[string]any{
+					"enabled_labs_experiments": []any{"keep"},
+				},
+			},
+			flags:    []string{"foo", "bar"},
+			want:     []string{"foo", "bar"},
+			wantList: []any{"keep", "foo@2", "bar@2"},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := setFlagsDisabled(tc.input, tc.flags)
+			if tc.wantNil && got != nil {
+				t.Fatalf("expected nil changed list, got %v", got)
+			}
+			if !tc.wantNil && len(tc.want) > 0 {
+				sort.Strings(got)
+				want := append([]string(nil), tc.want...)
+				sort.Strings(want)
+				if !reflect.DeepEqual(got, want) {
+					t.Fatalf("changed list mismatch: got %v want %v", got, want)
+				}
+			}
+			browser, _ := tc.input["browser"].(map[string]any)
+			if browser == nil {
+				t.Fatalf("expected browser key to exist")
+			}
+			gotList, _ := browser["enabled_labs_experiments"].([]any)
+			if !reflect.DeepEqual(gotList, tc.wantList) {
+				t.Fatalf("list mismatch: got %v want %v", gotList, tc.wantList)
+			}
+		})
+	}
+}

internal/chrome/patch.go

@@ -14,6 +14,12 @@ type PatchResult struct {
 	GLICEligiblePatched                             bool
 	VariationsCountryPatched                        bool
 	VariationsPermanentConsistencyCountryWasPatched bool
+	DisabledFlags                                   []string
+}
+
+// PatchOptions controls which transforms PatchLocalState applies.
+type PatchOptions struct {
+	DisableAIDownloadFlags bool
 }
 
 func ReadLastVersion(userDataPath string) (string, error) {
@@ -26,7 +32,7 @@ func ReadLastVersion(userDataPath string) (string, error) {
 }
 
 // PatchLocalState updates Local State for one Chrome profile directory.
-func PatchLocalState(userDataPath, lastVersion string, dryRun bool) (PatchResult, error) {
+func PatchLocalState(userDataPath, lastVersion string, dryRun bool, opts PatchOptions) (PatchResult, error) {
 	localStateFile := filepath.Join(userDataPath, "Local State")
 	raw, err := os.ReadFile(localStateFile)
 	if err != nil {
@@ -64,6 +70,13 @@ func PatchLocalState(userDataPath, lastVersion string, dryRun bool) (PatchResult
 		}
 	}
 
+	if opts.DisableAIDownloadFlags {
+		if changed := setFlagsDisabled(localState, AIDownloadFlagNames); len(changed) > 0 {
+			result.DisabledFlags = changed
+			result.Modified = true
+		}
+	}
+
 	if !result.Modified || dryRun {
 		return result, nil
 	}