Merge pull request #26939 from element-hq/valere/rust_rollout_phase_0

Update `element.io develop` configuration to migrate all existing users to the new rust crypto stack

docs/labs.md

@@ -116,6 +116,23 @@ Configures Element to use a new cryptography implementation based on the [matrix
 
 This setting is (currently) _sticky_ to a user's session: it only takes effect when the user logs in to a new session. Likewise, even after disabling the setting in `config.json`, the Rust implementation will remain in use until users log out.
 
+This configuration value is now set to `true` by default. This means that without any additional configuration
+every new login will use the new cryptography implementation.
+
+For administrators looking to transition existing users to the new stack, the `RustCrypto.staged_rollout_percent` configuration is available.
+This configuration allows for a phased migration of users, represented as an integer percentage (0 to 100). By default, this value is set to `0`,
+which means no existing users will be migrated to the new stack. If you wish to migrate all users, you can adjust this value to `100`.
+
+This configuration should be placed under the `setting_defaults` section as shown:
+
+```
+    "setting_defaults": {
+        "RustCrypto.staged_rollout_percent": 20
+    },
+```
+
+By adjusting the `RustCrypto.staged_rollout_percent` value, you can control the migration process according to your deployment strategy.
+
 ## New room header & details (`feature_new_room_decoration_ui`) [In Development]
 
 Refactors visually the room header and room sidebar

element.io/develop/config.json

@@ -49,10 +49,12 @@
     "privacy_policy_url": "https://element.io/cookie-policy",
     "features": {
         "feature_video_rooms": true,
-        "feature_rust_crypto": true,
         "feature_new_room_decoration_ui": true,
         "feature_element_call_video_rooms": true
     },
+    "setting_defaults": {
+        "RustCrypto.staged_rollout_percent": 100
+    },
     "element_call": {
         "url": "https://call.element.dev"
     },