diff --git a/scripts/install.cmd b/scripts/install.cmd
index 855d67ca3..ba0e2cf17 100644
--- a/scripts/install.cmd
+++ b/scripts/install.cmd
@@ -714,6 +714,16 @@ if !ERRORLEVEL! equ 0 (
         echo Installed Gemini commands to !GEMINI_COMMANDS_DIR!\
     )
 
+    REM Antigravity CLI plugin commands (only when detected)
+    set "AGY_BASE="
+    if exist "%USERPROFILE%\.gemini\config" (set "AGY_BASE=%USERPROFILE%\.gemini\config") else if exist "%USERPROFILE%\.gemini\antigravity-cli" set "AGY_BASE=%USERPROFILE%\.gemini\antigravity-cli"
+    if defined AGY_BASE if exist "apps\gemini\commands" (
+        set "AGY_PLUGIN_COMMANDS_DIR=!AGY_BASE!\plugins\plannotator\commands"
+        if not exist "!AGY_PLUGIN_COMMANDS_DIR!" mkdir "!AGY_PLUGIN_COMMANDS_DIR!"
+        xcopy /y /q "apps\gemini\commands\*.toml" "!AGY_PLUGIN_COMMANDS_DIR!\" >nul 2>&1
+        echo Installed Antigravity commands to !AGY_PLUGIN_COMMANDS_DIR!\
+    )
+
     REM Kiro -> hand-maintained kiro skills (3) + 2 extras, only when detected.
     if "!KIRO_AVAILABLE!"=="1" if exist "apps\kiro-cli\skills" (
         if not exist "!KIRO_SKILLS_DIR!" mkdir "!KIRO_SKILLS_DIR!"
@@ -902,6 +912,39 @@ echo }
     REM checkout in the git-gated skills/commands block above, not written here.
 )
 
+REM --- Antigravity CLI support (only when detected) ---
+set "AGY_BASE="
+if exist "%USERPROFILE%\.gemini\config" (set "AGY_BASE=%USERPROFILE%\.gemini\config") else if exist "%USERPROFILE%\.gemini\antigravity-cli" set "AGY_BASE=%USERPROFILE%\.gemini\antigravity-cli"
+if defined AGY_BASE (
+    set "AGY_PLUGIN_DIR=!AGY_BASE!\plugins\plannotator"
+    set "AGY_POLICIES_DIR=!AGY_BASE!\policies"
+    if not exist "!AGY_POLICIES_DIR!" mkdir "!AGY_POLICIES_DIR!"
+    if not exist "!AGY_PLUGIN_DIR!" mkdir "!AGY_PLUGIN_DIR!"
+    (
+        echo # Plannotator policy for Antigravity CLI
+        echo # Allows exit_plan_mode without TUI confirmation so the browser UI is the sole gate.
+        echo [[rule]]
+        echo toolName = "exit_plan_mode"
+        echo decision = "allow"
+        echo priority = 100
+    ) > "!AGY_POLICIES_DIR!\plannotator.toml"
+    >"!AGY_PLUGIN_DIR!\plugin.json" echo {"name":"plannotator"}
+    >"!AGY_PLUGIN_DIR!\hooks.json" echo {"hooks":{"BeforeTool":[{"matcher":"exit_plan_mode","hooks":[{"type":"command","command":"plannotator","timeout":345600}]}]}}
+    echo Installed Antigravity plugin to !AGY_PLUGIN_DIR!
+)
+
+echo.
+echo ==========================================
+echo   ANTIGRAVITY CLI USERS
+echo ==========================================
+echo.
+echo Plannotator is installed as an Antigravity plugin.
+echo Restart the CLI, and the following commands will be ready:
+echo.
+echo   /plannotator-review
+echo   /plannotator-annotate
+echo.
+echo Plans will automatically open in your browser during plan reviews.
 echo.
 echo ==========================================
 echo   KIRO CLI USERS
diff --git a/scripts/install.ps1 b/scripts/install.ps1
index 7a32df189..93b2b1f9b 100644
--- a/scripts/install.ps1
+++ b/scripts/install.ps1
@@ -800,6 +800,18 @@ try {
                     Write-Host "Installed Gemini slash commands to $geminiCommandsDir\"
                 }
             }
+
+            # Antigravity CLI plugin commands (only when detected)
+            $agyBase = if (Test-Path "$env:USERPROFILE\.gemini\config") { "$env:USERPROFILE\.gemini\config" } elseif (Test-Path "$env:USERPROFILE\.gemini\antigravity-cli") { "$env:USERPROFILE\.gemini\antigravity-cli" } else { $null }
+            if ($agyBase -and (Test-Path "apps\gemini\commands")) {
+                $agyPluginCommandsDir = "$agyBase\plugins\plannotator\commands"
+                $geminiCmds = Get-ChildItem "apps\gemini\commands\*.toml" -ErrorAction SilentlyContinue
+                if ($geminiCmds) {
+                    New-Item -ItemType Directory -Force -Path $agyPluginCommandsDir | Out-Null
+                    Copy-Item -Force "apps\gemini\commands\*.toml" $agyPluginCommandsDir
+                    Write-Host "Installed Antigravity slash commands to $agyPluginCommandsDir\"
+                }
+            }
         } finally {
             Pop-Location
         }
@@ -967,6 +979,24 @@ fs.writeFileSync('$($geminiSettings.Replace('\','/'))', JSON.stringify(settings,
     # (apps/gemini/commands) in the git-gated skills/commands install above.
 }
 
+# --- Antigravity CLI support (only when detected) ---
+$agyBase = if (Test-Path "$env:USERPROFILE\.gemini\config") { "$env:USERPROFILE\.gemini\config" } elseif (Test-Path "$env:USERPROFILE\.gemini\antigravity-cli") { "$env:USERPROFILE\.gemini\antigravity-cli" } else { $null }
+if ($agyBase) {
+    $agyPluginDir = "$agyBase\plugins\plannotator"
+    New-Item -ItemType Directory -Force -Path "$agyBase\policies", $agyPluginDir | Out-Null
+    @'
+# Plannotator policy for Antigravity CLI
+# Allows exit_plan_mode without TUI confirmation so the browser UI is the sole gate.
+[[rule]]
+toolName = "exit_plan_mode"
+decision = "allow"
+priority = 100
+'@ | Set-Content -Path "$agyBase\policies\plannotator.toml"
+    '{"name":"plannotator"}' | Set-Content -Path "$agyPluginDir\plugin.json"
+    '{"hooks":{"BeforeTool":[{"matcher":"exit_plan_mode","hooks":[{"type":"command","command":"plannotator","timeout":345600}]}]}}' | Set-Content -Path "$agyPluginDir\hooks.json"
+    Write-Host "Installed Antigravity plugin to $agyPluginDir"
+}
+
 Write-Host ""
 Write-Host "=========================================="
 Write-Host "  OPENCODE USERS"
@@ -999,6 +1029,18 @@ if ($kiroAvailable) {
 }
 Write-Host ""
 Write-Host "=========================================="
+Write-Host "  ANTIGRAVITY CLI USERS"
+Write-Host "=========================================="
+Write-Host ""
+Write-Host "Plannotator is installed as an Antigravity plugin."
+Write-Host "Restart the CLI, and the following commands will be ready:"
+Write-Host ""
+Write-Host "  /plannotator-review"
+Write-Host "  /plannotator-annotate"
+Write-Host ""
+Write-Host "Plans will automatically open in your browser during plan reviews."
+Write-Host ""
+Write-Host "=========================================="
 Write-Host "  CLAUDE CODE USERS: YOU ARE ALL SET!"
 Write-Host "=========================================="
 Write-Host ""
diff --git a/scripts/install.sh b/scripts/install.sh
index f3aaa97a9..4e55f164f 100644
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1131,6 +1131,13 @@ checkout_failed=0
         echo "Installed Gemini commands to ${GEMINI_COMMANDS_DIR}/"
     fi
 
+    # Antigravity CLI plugin commands (only when detected)
+    AGY_BASE=""; [ -d "$HOME/.gemini/config" ] && AGY_BASE="$HOME/.gemini/config" || { [ -d "$HOME/.gemini/antigravity-cli" ] && AGY_BASE="$HOME/.gemini/antigravity-cli"; }
+    if [ -n "$AGY_BASE" ] && [ -d "apps/gemini/commands" ] && [ -n "$(ls -A apps/gemini/commands 2>/dev/null)" ]; then
+        copy_commands_if_present apps/gemini/commands "$AGY_BASE/plugins/plannotator/commands"
+        echo "Installed Antigravity commands to ${AGY_BASE}/plugins/plannotator/commands/"
+    fi
+
     if [ "$kiro_available" -eq 1 ] && [ -d "apps/kiro-cli/skills" ] && [ -n "$(ls -A apps/kiro-cli/skills 2>/dev/null)" ]; then
         mkdir -p "$KIRO_SKILLS_DIR"
         # Kiro-specific skills (origin baked in) come from apps/kiro-cli/skills.
@@ -1297,6 +1304,28 @@ GEMINI_SETTINGS_EOF
     # the skills/commands install block above (apps/gemini/commands).
 fi
 
+# --- Antigravity CLI support (only when detected) ---
+AGY_BASE=""; [ -d "$HOME/.gemini/config" ] && AGY_BASE="$HOME/.gemini/config" || { [ -d "$HOME/.gemini/antigravity-cli" ] && AGY_BASE="$HOME/.gemini/antigravity-cli"; }
+if [ -n "$AGY_BASE" ]; then
+    AGY_PLUGIN_DIR="$AGY_BASE/plugins/plannotator"
+    mkdir -p "$AGY_BASE/policies" "$AGY_PLUGIN_DIR"
+    cat > "$AGY_BASE/policies/plannotator.toml" << 'AGY_POLICY_EOF'
+# Plannotator policy for Antigravity CLI
+# Allows exit_plan_mode without TUI confirmation so the browser UI is the sole gate.
+[[rule]]
+toolName = "exit_plan_mode"
+decision = "allow"
+priority = 100
+AGY_POLICY_EOF
+    cat > "$AGY_PLUGIN_DIR/plugin.json" << 'AGY_PLUGIN_EOF'
+{"name":"plannotator"}
+AGY_PLUGIN_EOF
+    cat > "$AGY_PLUGIN_DIR/hooks.json" << 'AGY_HOOKS_EOF'
+{"hooks":{"BeforeTool":[{"matcher":"exit_plan_mode","hooks":[{"type":"command","command":"plannotator","timeout":345600}]}]}}
+AGY_HOOKS_EOF
+    echo "Installed Antigravity plugin to ${AGY_PLUGIN_DIR}"
+fi
+
 echo ""
 echo "=========================================="
 echo "  OPENCODE USERS"
@@ -1330,6 +1359,18 @@ echo "If settings.json was not auto-configured, see:"
 echo "  ~/.gemini/settings.json (add BeforeTool hook)"
 echo ""
 echo "=========================================="
+echo "  ANTIGRAVITY CLI USERS"
+echo "=========================================="
+echo ""
+echo "Plannotator is installed as an Antigravity plugin."
+echo "Restart the CLI, and the following commands will be ready:"
+echo ""
+echo "  /plannotator-review"
+echo "  /plannotator-annotate"
+echo ""
+echo "Plans will automatically open in your browser during plan reviews."
+echo ""
+echo "=========================================="
 echo "  CODEX USERS"
 echo "=========================================="
 echo ""
diff --git a/scripts/install.test.ts b/scripts/install.test.ts
index 2d95376d4..063d2ba69 100644
--- a/scripts/install.test.ts
+++ b/scripts/install.test.ts
@@ -284,6 +284,12 @@ describe("install.sh", () => {
     expect(script).toContain('GEMINI_POLICY_EOF');
     expect(script).toContain('GEMINI_SETTINGS_EOF');
   });
+
+  test("installs Antigravity plugin configuration", () => {
+    expect(script).toContain("AGY_BASE=");
+    expect(script).toContain("plannotator.toml");
+    expect(script).toContain("hooks.json");
+  });
 });
 
 describe("install.ps1", () => {
@@ -424,6 +430,12 @@ describe("install.ps1", () => {
     expect(skillsInstallIndex).toBeGreaterThan(0);
     expect(piUpdateCallIndex).toBeGreaterThan(skillsInstallIndex);
   });
+
+  test("installs Antigravity plugin configuration on Windows", () => {
+    expect(script).toContain("$agyBase");
+    expect(script).toContain("plannotator.toml");
+    expect(script).toContain("hooks.json");
+  });
 });
 
 describe("install.cmd", () => {
@@ -580,6 +592,12 @@ describe("install.cmd", () => {
     // Enforcement: hard-fail when opted in but gh missing
     expect(script).toContain("gh CLI was not found");
   });
+
+  test("installs Antigravity plugin configuration in cmd", () => {
+    expect(script).toContain("AGY_BASE");
+    expect(script).toContain("plannotator.toml");
+    expect(script).toContain("hooks.json");
+  });
 });
 
 describe("Core Plannotator skills", () => {