Patterns

The Build a code hosting platform guide gets Git working: clone, push, and pages to read the result on. These patterns build on it. None of them is needed to serve Git.

Each page is written against the app the guide produces, and changes a part of it. Read the one you want; they do not need to be read in order.

Pattern	What it is	Carried by
Repository lifecycle	Create, rename, and delete a repository, or make one by pushing to it	RepositoryService, authorize
Protected branches	Refuse a force-push or a delete on a branch	pre_receive
Merge requests	Open one, show the change, merge it	post_receive, FindMergeBases, DiffCommit, IsAncestor, UpdateRefs
Merge queue	Land on evidence, with no lock and no worker	IsAncestor, UpdateRefs
Checks	Evidence instead of CI: whoever ran it reports the verdict	Your own tables
Private repositories	Who may read, and which refs they are told about	authorize, visible_refs
Deploy keys	A credential scoped to one repository, and bot actors	authorize
CI on push	Build what landed, and read what changed	post_receive, DiffCommit, ListRefs
Mirroring	Sync refs to another host as they land	post_receive, ListRefs, PushToRemote

Browsing a repository and rendering diffs are not here. They are chapter 6 and chapter 7 of the guide.

What every pattern assumes

These hold everywhere and are stated once, where they belong:

Assumption	Stated in
The key is yours, and the create is idempotent on it	Repository keys
actor is an ID in your namespace, never a credential	authorize
An absent object ID is an unset field, never forty zeros	ObjectId
A refusal is per ref, and an unjudged command fails the push	pre_receive
Enroute holds no policy of its own	Hooks

Two rules are about design rather than the contract, and every page here depends on them:

A rule lives outside what it gates. A policy a pusher can change by pushing is not a policy. What a merge is gated on belongs in your app's own configuration, reviewed and deployed like the rest of it, never in a file in the branch under test.

UpdateRefs does not run pre_receive. Use it for application-controlled merges instead of introducing a privileged Git identity solely to bypass a push rule.

Examples

The code is TypeScript on Next.js, continuing the guide's app: lib/store.ts for your own data, lib/enroute.ts for the client, and lib/hooks/ for the four calls. The contract is language-neutral, and so are these patterns — translate them into whatever you are building in.