feat(core): implement feature lifecycle management (Alpha, Beta, GA)

docs/reference/configuration.md

@@ -83,6 +83,16 @@ contain other project-specific files related to Gemini CLI's operation, such as:
 Settings are organized into categories. All settings should be placed within
 their corresponding top-level category object in your `settings.json` file.
 
+#### Feature Lifecycle
+
+Gemini CLI uses a feature lifecycle management system to manage experimental and
+optional features. Features are categorized by their stability stage (`ALPHA`,
+`BETA`, `GA`, `DEPRECATED`).
+
+For a detailed explanation of feature stages and a list of all available
+features, see the
+[Feature Lifecycle documentation](/docs/cli/feature-lifecycle.md).
+
 <!-- SETTINGS-AUTOGEN:START -->
 
 #### `policyPaths`
@@ -1056,7 +1066,6 @@ their corresponding top-level category object in your `settings.json` file.
     `gemma3-1b-gpu-custom`.
   - **Default:** `"gemma3-1b-gpu-custom"`
   - **Requires restart:** Yes
-
 #### `skills`
 
 - **`skills.enabled`** (boolean):
@@ -1165,6 +1174,77 @@ their corresponding top-level category object in your `settings.json` file.
 - **`admin.skills.enabled`** (boolean):
   - **Description:** If false, disallows agent skills from being used.
   - **Default:** `true`
+
+#### `features`
+
+- **`features.allAlpha`** (boolean):
+  - **Description:** Enable all Alpha features by default.
+  - **Default:** `false`
+  - **Requires restart:** Yes
+
+- **`features.allBeta`** (boolean):
+  - **Description:** Enable all Beta features by default.
+  - **Default:** `true`
+  - **Requires restart:** Yes
+
+- **`features.toolOutputMasking`** (boolean):
+  - **Description:** Enables tool output masking to save tokens.
+  - **Default:** `true`
+  - **Stage:** BETA
+  - **Requires restart:** Yes
+
+- **`features.enableAgents`** (boolean):
+  - **Description:** Enable local and remote subagents.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
+
+- **`features.extensionManagement`** (boolean):
+  - **Description:** Enable extension management features.
+  - **Default:** `true`
+  - **Stage:** BETA
+  - **Requires restart:** Yes
+
+- **`features.extensionConfig`** (boolean):
+  - **Description:** Enable requesting and fetching of extension settings.
+  - **Default:** `true`
+  - **Stage:** BETA
+  - **Requires restart:** Yes
+
+- **`features.extensionRegistry`** (boolean):
+  - **Description:** Enable extension registry explore UI.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
+
+- **`features.extensionReloading`** (boolean):
+  - **Description:** Enables extension loading/unloading within the CLI session.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
+
+- **`features.jitContext`** (boolean):
+  - **Description:** Enable Just-In-Time (JIT) context loading.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
+
+- **`features.useOSC52Paste`** (boolean):
+  - **Description:** Use OSC 52 sequence for pasting.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+
+- **`features.plan`** (boolean):
+  - **Description:** Enable planning features (Plan Mode and tools).
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
+
+- **`features.zedIntegration`** (boolean):
+  - **Description:** Enable Zed integration.
+  - **Default:** `false`
+  - **Stage:** ALPHA
+  - **Requires restart:** Yes
   <!-- SETTINGS-AUTOGEN:END -->
 
 #### `mcpServers`
@@ -1350,6 +1430,10 @@ the `advanced.excludedEnvVars` setting in your `settings.json` file.
     is useful when running Gemini CLI in a standalone terminal while still
     wanting to associate it with a specific IDE instance.
   - Overrides the automatic IDE detection logic.
+- **`GEMINI_FEATURE_GATES`**:
+  - Specifies a comma-separated list of feature key-value pairs to override the
+    default feature states.
+  - Example: `export GEMINI_FEATURE_GATES="plan=true,enableAgents=false"`
 - **`GEMINI_CLI_HOME`**:
   - Specifies the root directory for Gemini CLI's user-level configuration and
     storage.
@@ -1551,13 +1635,17 @@ for that specific session.
     - `auto_edit`: Automatically approve edit tools (replace, write_file) while
       prompting for others
     - `yolo`: Automatically approve all tool calls (equivalent to `--yolo`)
-    - `plan`: Read-only mode for tool calls (requires experimental planning to
-      be enabled).
+    - `plan`: Read-only mode for tool calls (requires planning feature to be
+      enabled).
       > **Note:** This mode is currently under development and not yet fully
       > functional.
   - Cannot be used together with `--yolo`. Use `--approval-mode=yolo` instead of
     `--yolo` for the new unified approach.
   - Example: `gemini --approval-mode auto_edit`
+- **`--feature-gates <key1=val1,key2=val2,...>`**:
+  - A comma-separated list of feature key-value pairs to override the default
+    feature states for this session.
+  - Example: `gemini --feature-gates "plan=true,enableAgents=false"`
 - **`--allowed-tools <tool1,tool2,...>`**:
   - A comma-separated list of tool names that will bypass the confirmation
     dialog.