diff --git a/internal/cli/gga_available_test.go b/internal/cli/gga_available_test.go
index ef3628483..5b3550f9f 100644
--- a/internal/cli/gga_available_test.go
+++ b/internal/cli/gga_available_test.go
@@ -54,6 +54,64 @@ func TestGGAAvailableDetectsViaLocalBin(t *testing.T) {
 	}
 }
 
+// TestGGAAvailableDetectsViaWindowsPS1 verifies that ggaAvailable returns true
+// when the Windows PowerShell shim exists in ~/bin/gga.ps1.
+func TestGGAAvailableDetectsViaWindowsPS1(t *testing.T) {
+	tmpHome := t.TempDir()
+	binDir := filepath.Join(tmpHome, "bin")
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(binDir, "gga.ps1"), []byte("fake"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	origLookPath := cmdLookPath
+	origHomeDir := osUserHomeDir
+	origStat := osStat
+	cmdLookPath = func(file string) (string, error) { return "", os.ErrNotExist }
+	osUserHomeDir = func() (string, error) { return tmpHome, nil }
+	osStat = os.Stat
+	t.Cleanup(func() {
+		cmdLookPath = origLookPath
+		osUserHomeDir = origHomeDir
+		osStat = origStat
+	})
+
+	if !ggaAvailable(system.PlatformProfile{OS: "windows", PackageManager: "winget"}) {
+		t.Fatal("ggaAvailable() = false, want true when gga.ps1 exists on Windows")
+	}
+}
+
+// TestGGAAvailableDetectsViaWindowsExe verifies that ggaAvailable returns true
+// when a native Windows executable exists in ~/bin/gga.exe.
+func TestGGAAvailableDetectsViaWindowsExe(t *testing.T) {
+	tmpHome := t.TempDir()
+	binDir := filepath.Join(tmpHome, "bin")
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(binDir, "gga.exe"), []byte("fake"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	origLookPath := cmdLookPath
+	origHomeDir := osUserHomeDir
+	origStat := osStat
+	cmdLookPath = func(file string) (string, error) { return "", os.ErrNotExist }
+	osUserHomeDir = func() (string, error) { return tmpHome, nil }
+	osStat = os.Stat
+	t.Cleanup(func() {
+		cmdLookPath = origLookPath
+		osUserHomeDir = origHomeDir
+		osStat = origStat
+	})
+
+	if !ggaAvailable(system.PlatformProfile{OS: "windows", PackageManager: "winget"}) {
+		t.Fatal("ggaAvailable() = false, want true when gga.exe exists on Windows")
+	}
+}
+
 // TestGGAAvailableDetectsViaHomebrewOptPrefix verifies that ggaAvailable returns
 // true when gga exists at /opt/homebrew/bin/gga (Apple Silicon Homebrew default).
 func TestGGAAvailableDetectsViaHomebrewOptPrefix(t *testing.T) {
diff --git a/internal/cli/run.go b/internal/cli/run.go
index b1e5853b6..55afd7e62 100644
--- a/internal/cli/run.go
+++ b/internal/cli/run.go
@@ -715,8 +715,10 @@ func ggaAvailable(profile system.PlatformProfile) bool {
 		}
 	}
 	if profile.OS == "windows" {
-		if _, err := osStat(filepath.Join(homeDir, "bin", "gga")); err == nil {
-			return true
+		for _, name := range []string{"gga.ps1", "gga.exe", "gga"} {
+			if _, err := osStat(filepath.Join(homeDir, "bin", name)); err == nil {
+				return true
+			}
 		}
 	}
 	return false
diff --git a/internal/update/check_test.go b/internal/update/check_test.go
index 255752cb3..59a2e46e9 100644
--- a/internal/update/check_test.go
+++ b/internal/update/check_test.go
@@ -6,7 +6,9 @@ import (
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"os/exec"
+	"path/filepath"
 	"testing"
 
 	"github.com/gentleman-programming/gentle-ai/internal/system"
@@ -118,6 +120,97 @@ func TestDetectInstalledVersion(t *testing.T) {
 	}
 }
 
+func TestDetectInstalledVersionWindowsShim(t *testing.T) {
+	tmpHome := t.TempDir()
+	binDir := filepath.Join(tmpHome, "bin")
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(binDir, "gga.ps1"), []byte("fake"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	origLookPath := lookPath
+	origExecCommand := execCommand
+	origRuntimeGOOS := runtimeGOOS
+	origHomeDir := osUserHomeDir
+	origStat := osStat
+	t.Cleanup(func() {
+		lookPath = origLookPath
+		execCommand = origExecCommand
+		runtimeGOOS = origRuntimeGOOS
+		osUserHomeDir = origHomeDir
+		osStat = origStat
+	})
+
+	lookPath = func(string) (string, error) { return "", os.ErrNotExist }
+	runtimeGOOS = "windows"
+	osUserHomeDir = func() (string, error) { return tmpHome, nil }
+	osStat = os.Stat
+
+	got := detectInstalledVersion(context.Background(), ToolInfo{Name: "gga", DetectCmd: []string{"gga", "--version"}}, "dev")
+	if got != "unknown" {
+		t.Fatalf("detectInstalledVersion() = %q, want unknown when windows shim exists", got)
+	}
+}
+
+// TestCheckFilteredWindowsShimKeepsGGAVisible verifies the integrated update
+// flow keeps GGA visible on Windows when the PowerShell shim exists.
+func TestCheckFilteredWindowsShimKeepsGGAVisible(t *testing.T) {
+	tmpHome := t.TempDir()
+	binDir := filepath.Join(tmpHome, "bin")
+	if err := os.MkdirAll(binDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(binDir, "gga.ps1"), []byte("fake"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		json.NewEncoder(w).Encode(githubRelease{TagName: "v2.0.0", HTMLURL: "https://github.com/Gentleman-Programming/gentleman-guardian-angel/releases/tag/v2.0.0"})
+	}))
+	defer server.Close()
+
+	origClient := httpClient
+	origLookPath := lookPath
+	origExecCommand := execCommand
+	origRuntimeGOOS := runtimeGOOS
+	origHomeDir := osUserHomeDir
+	origStat := osStat
+	t.Cleanup(func() {
+		httpClient = origClient
+		lookPath = origLookPath
+		execCommand = origExecCommand
+		runtimeGOOS = origRuntimeGOOS
+		osUserHomeDir = origHomeDir
+		osStat = origStat
+	})
+
+	httpClient = server.Client()
+	httpClient.Transport = &testTransport{server: server}
+	lookPath = func(string) (string, error) { return "", os.ErrNotExist }
+	execCommand = func(name string, args ...string) *exec.Cmd { return exec.Command("false") }
+	runtimeGOOS = "windows"
+	osUserHomeDir = func() (string, error) { return tmpHome, nil }
+	osStat = os.Stat
+
+	results := CheckFiltered(context.Background(), "1.0.0", system.PlatformProfile{OS: "windows", PackageManager: "winget", Supported: true}, []string{"gga"})
+	if len(results) != 1 {
+		t.Fatalf("CheckFiltered() len = %d, want 1", len(results))
+	}
+	if results[0].Tool.Name != "gga" {
+		t.Fatalf("CheckFiltered() tool = %q, want gga", results[0].Tool.Name)
+	}
+	if results[0].Status != VersionUnknown {
+		t.Fatalf("CheckFiltered() status = %q, want %q for Windows shim visibility", results[0].Status, VersionUnknown)
+	}
+	if results[0].Status == NotInstalled {
+		t.Fatal("CheckFiltered() unexpectedly reported GGA as NotInstalled on Windows shim path")
+	}
+}
+
 func TestParseVersionFromOutput_DevSentinel(t *testing.T) {
 	if got := parseVersionFromOutput("engram dev"); got != "dev" {
 		t.Fatalf("parseVersionFromOutput(engram dev) = %q, want %q", got, "dev")
diff --git a/internal/update/detect.go b/internal/update/detect.go
index 8349d99df..ab7d54639 100644
--- a/internal/update/detect.go
+++ b/internal/update/detect.go
@@ -2,16 +2,22 @@ package update
 
 import (
 	"context"
+	"os"
 	"os/exec"
+	"path/filepath"
 	"regexp"
+	"runtime"
 	"strings"
 	"time"
 )
 
 // Package-level vars for testability (swap in tests via t.Cleanup).
 var (
-	execCommand = exec.Command
-	lookPath    = exec.LookPath
+	execCommand   = exec.Command
+	lookPath      = exec.LookPath
+	osUserHomeDir = os.UserHomeDir
+	osStat        = os.Stat
+	runtimeGOOS   = runtime.GOOS
 )
 
 // versionRegexp extracts a semver-like version from command output.
@@ -36,6 +42,9 @@ func detectInstalledVersion(ctx context.Context, tool ToolInfo, currentBuildVers
 
 	binary := tool.DetectCmd[0]
 	if _, err := lookPath(binary); err != nil {
+		if binary == "gga" && ggaShimInstalledOnWindows() {
+			return "unknown"
+		}
 		return "" // binary not found
 	}
 
@@ -68,6 +77,25 @@ func detectInstalledVersion(ctx context.Context, tool ToolInfo, currentBuildVers
 	return parseVersionFromOutput(strings.TrimSpace(string(out)))
 }
 
+func ggaShimInstalledOnWindows() bool {
+	if runtimeGOOS != "windows" {
+		return false
+	}
+
+	homeDir, err := osUserHomeDir()
+	if err != nil {
+		return false
+	}
+
+	for _, name := range []string{"gga.ps1", "gga.exe", "gga"} {
+		if _, err := osStat(filepath.Join(homeDir, "bin", name)); err == nil {
+			return true
+		}
+	}
+
+	return false
+}
+
 // parseVersionFromOutput extracts the first semver-like pattern from raw output.
 func parseVersionFromOutput(output string) string {
 	if output == "" {