commit 39b4f270d7392dc6eebfc2310e62aac1bae3bb33
parent e427768e823658da89832dd9d1bbeaa18480c017
Author: DonalMe <76789979+DonalMe@users.noreply.github.com>
Date: Mon, 8 Dec 2025 17:15:57 +0000
Bug 2004731 - Update the Pocket Guide to reference Train-Hop and Emergency Pref Flips. r=release-managers,RyanVM DONTBUILD
Differential Revision: https://phabricator.services.mozilla.com/D275479
Diffstat:
1 file changed, 21 insertions(+), 0 deletions(-)
diff --git a/docs/contributing/pocket-guide-shipping-firefox.rst b/docs/contributing/pocket-guide-shipping-firefox.rst
@@ -205,6 +205,8 @@ Within Firefox we allow the ability to enable/disable bits of code or entire fea
especially useful when conducting experiments or a gradual rollout of high risk features
to our Release population.
+ A Pref Rollout can also be used to mitigate an incident, see `Incident Response Pref Flips <https://experimenter.info/desktop-incident-response>`__ for details.
+
Further Reading/Useful links:
- `Mozilla preferences documentation <https://firefox-source-docs.mozilla.org/modules/libpref/index.html>`__
@@ -262,6 +264,25 @@ Further Reading/Useful links:
(Follow the ‘help’ links to learn more)
- `Telemetry <https://wiki.mozilla.org/Telemetry>`__
+Train-Hop
+~~~~~~~~~~~
+
+Extensions in browser/extensions/ can run inside of Firefox as a “built-in addon”.
+Unlike traditional WebExtensions, these add-ons ship with Firefox and run with the same privilege level as the rest of the browser code.
+
+When a built-in add-on is packaged up as an XPI and deployed to Beta or Release clients, it is referred to as a “train-hop”.
+A train-hop supplements the default Firefox train release model by allowing teams to ship code changes without requiring a dot release.
+
+By default, the code for built-in add-ons rides the standard Firefox release train.
+A train-hop only occurs when the extension is intentionally packaged and shipped off-train.
+
+The extensions that currently support train-hops are New Tab and Web Compatibility.
+
+Further Reading/Useful links:
+
+- `Web Compatibility Release Process <https://wiki.mozilla.org/Compatibility/System_Addon/Release_Process#Shipping_interventions_with_an_out-of-band_System_Addon_Update>`__
+- `Train-hopping for New Tab <https://firefox-source-docs.mozilla.org/browser/extensions/newtab/docs/v2-system-addon/train_hopping.html>`__
+
Definitions
-----------
