Add review policy doc

README.md

@@ -223,6 +223,11 @@ Before attempting to develop on Riot you **must** read the [developer guide
 for `matrix-react-sdk`](https://github.com/matrix-org/matrix-react-sdk), which
 also defines the design, architecture and style for Riot too.
 
+Before starting work on a feature, it's best to ensure your plan aligns well
+with our vision for Riot. Please chat with the team in
+[#riot-dev:matrix.org](https://matrix.to/#/#riot-dev:matrix.org) before you
+start so we can ensure it's something we'd be willing to merge.
+
 You should also familiarise yourself with the ["Here be Dragons" guide
 ](https://docs.google.com/document/d/12jYzvkidrp1h7liEuLIe6BMdU0NUjndUYI971O06ooM)
 to the tame & not-so-tame dragons (gotchas) which exist in the codebase.

docs/review.md

@@ -0,0 +1,81 @@
+# Review Guidelines
+
+The following summarises review guidelines that we follow for pull requests in
+Riot Web and other supporting repos. These are just guidelines (not strict
+rules) and may be updated over time.
+
+## Code Review
+
+When reviewing code, here are some things we look for and also things we avoid:
+
+### We review for
+
+* Correctness
+* Performance
+* Accessibility
+* Security
+* Comments and documentation where needed
+* Sharing knowledge of different areas among the team
+* Ensuring it's something we're comfortable maintaining for the long term
+
+### We should avoid
+
+* Style nits that are already handled by the linter
+* Dramatically increasing scope
+
+### Good practices
+
+* Use empathetic language
+  * See also [Mindful Communication in Code
+    Reviews](https://kickstarter.engineering/a-guide-to-mindful-communication-in-code-reviews-48aab5282e5e)
+    and [How to Do Code Reviews Like a Human](https://mtlynch.io/human-code-reviews-1/)
+* Authors should prefer smaller commits for easier reviewing and bisection
+* Reviewers should be explicit about required versus optional changes
+  * Reviews are conversations and the PR author should feel comfortable
+    discussing and pushing back on changes before making them
+* Core team should lead by example through their tone and language
+* Take the time to thank and point out good code changes
+* Using softer language like "please" and "what do you think?" goes a long way
+  towards making others feel like colleagues working towards a common goal
+
+### Workflow
+
+* Authors should request review from riot-web team by default (if someone on the
+  team is clearly the expert in an area, a direct review request to them may be
+  more appropriate)
+* Reviewers should remove the team review request and request review from
+  themselves when starting a review to avoid double review
+* Authors should link to other layers of their PR in their PR before requesting
+  review. Reviewers might be coming from different places and could miss other
+  required PRs.
+* Avoid force pushing to a PR after first round of review
+* Use the GitHub default of merge commits when landing (avoid alternate options
+  like squash or rebase)
+* PR author merges after review (assuming they have write access)
+* Assign issues only when in progress to indicate to others what can be picked
+  up
+
+## Design and Product Review
+
+We want to ensure that all changes to Riot fit with our design and product
+vision. We often request review from those teams so they can provide their
+perspective.
+
+In more detail, our usual process for changes that affect the UI or alter user
+functionality is:
+
+* For changes that will go live when merged, always flag Design and Product
+  teams as appropriate
+* For changes guarded by a feature flag, Design and Product review is not
+  required (though may still be useful) since we can continue tweaking
+
+As it can be difficult to review design work from looking at just the changed
+files in a PR, authors should be prepared for Design and / or Product teams to
+request a link to an ad-hoc build of Riot (hosted anywhere) that can be used for
+the review. In the future, we [hope to automate
+this](https://github.com/vector-im/riot-web/issues/12624) for every PR.
+
+Before starting work on a feature, it's best to ensure your plan aligns well
+with our vision for Riot. Please chat with the team in
+[#riot-dev:matrix.org](https://matrix.to/#/#riot-dev:matrix.org) before you
+start so we can ensure it's something we'd be willing to merge.