diff --git a/packages/client-runtime/package.json b/packages/client-runtime/package.json
index aea6ead6b9433e1791dae126e670e20dc6706573..987ba69fe02b73319572a9f84dd5c1eb533656d2 100644
--- a/packages/client-runtime/package.json
+++ b/packages/client-runtime/package.json
@@ -390,6 +390,10 @@
     "./state/mcp-apps": {
       "types": "./src/state/mcpApps.ts",
       "default": "./src/state/mcpApps.ts"
+    },
+    "./source-control-clients": {
+      "types": "./src/sourceControlClients.ts",
+      "default": "./src/sourceControlClients.ts"
     }
   },
   "scripts": {
@@ -399,6 +403,13 @@
   "dependencies": {
     "@t3tools/contracts": "workspace:*",
     "@t3tools/shared": "workspace:*",
+    "@t3tools/source-control-azure-devops": "workspace:*",
+    "@t3tools/source-control-bitbucket": "workspace:*",
+    "@t3tools/source-control-core": "workspace:*",
+    "@t3tools/source-control-forgejo": "workspace:*",
+    "@t3tools/source-control-gitcafe": "workspace:*",
+    "@t3tools/source-control-github": "workspace:*",
+    "@t3tools/source-control-gitlab": "workspace:*",
     "effect": "catalog:",
     "three": "0.180.0"
   },
diff --git a/packages/client-runtime/src/sourceControlClients.test.ts b/packages/client-runtime/src/sourceControlClients.test.ts
new file mode 100644
index 0000000000000000000000000000000000000000..11e1e1c09c9c3c0d4f3b8632445000538acbb28c
--- /dev/null
+++ b/packages/client-runtime/src/sourceControlClients.test.ts
@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { sourceControlClients } from "./sourceControlClients.ts";
+
+describe("sourceControlClients", () => {
+  it("reads a missing kind as the first host and an unshipped kind as the generic one", () => {
+    expect(sourceControlClients.get(undefined).kind).toBe("github");
+    expect(sourceControlClients.get("forkhost").kind).toBe("unknown");
+  });
+
+  it("gives a change request URL to the first host whose shape it has", () => {
+    // GitCafe and Forgejo share `/pulls/`; GitCafe only claims its own hostnames.
+    const kindOf = (url: string) => sourceControlClients.findByChangeRequestUrl(url)?.kind;
+    expect(kindOf("https://git.cafe/acme/web/pulls/7")).toBe("gitcafe");
+    expect(kindOf("https://codeberg.org/acme/web/pulls/7")).toBe("forgejo");
+  });
+});
diff --git a/packages/client-runtime/src/sourceControlClients.ts b/packages/client-runtime/src/sourceControlClients.ts
new file mode 100644
index 0000000000000000000000000000000000000000..108644a04b4dfdc05c8379a2a86e287f492167f1
--- /dev/null
+++ b/packages/client-runtime/src/sourceControlClients.ts
@@ -0,0 +1,41 @@
+/**
+ * The source control host definitions web and mobile ship, and the one lookup they use.
+ *
+ * Adding a host means writing its `@t3tools/source-control-<host>` package with a
+ * `./client/definition` entry and adding it here; clients then label, list, and check out its
+ * change requests without further branches.
+ *
+ * @module client-runtime/sourceControlClients
+ */
+import * as AzureDevOps from "@t3tools/source-control-azure-devops/client/definition";
+import * as Bitbucket from "@t3tools/source-control-bitbucket/client/definition";
+import { makeSourceControlClientRegistry } from "@t3tools/source-control-core/client/definition";
+
+export {
+  type ChangeRequestTerminology,
+  type SourceControlClientDefinition,
+} from "@t3tools/source-control-core/client/definition";
+import * as Forgejo from "@t3tools/source-control-forgejo/client/definition";
+import * as GitCafe from "@t3tools/source-control-gitcafe/client/definition";
+import * as GitHub from "@t3tools/source-control-github/client/definition";
+import * as GitLab from "@t3tools/source-control-gitlab/client/definition";
+
+/**
+ * GitHub comes first because a repository that has not reported its host yet reads as GitHub,
+ * which is what clients have always shown there. A change request URL goes to the first host
+ * whose shape it has, so GitCafe, which claims `/pulls/` only on its own hostnames, comes before
+ * Forgejo, which claims it everywhere. Pickers sort by readiness and label, not by this order.
+ */
+const BUILT_IN_SOURCE_CONTROL_CLIENTS = [
+  GitHub.definition,
+  GitLab.definition,
+  GitCafe.definition,
+  Forgejo.definition,
+  Bitbucket.definition,
+  AzureDevOps.definition,
+];
+
+/** `definitions` lists the built-in hosts in that order, for pickers that offer every host. */
+export const sourceControlClients = makeSourceControlClientRegistry(
+  BUILT_IN_SOURCE_CONTROL_CLIENTS,
+);
diff --git a/packages/source-control-azure-devops/package.json b/packages/source-control-azure-devops/package.json
index 10347850bf19c9d1d7ca7f001f99049df7bab0cb..4e5f9747c379fea83ce869f07a0b2eae36fe09b0 100644
--- a/packages/source-control-azure-devops/package.json
+++ b/packages/source-control-azure-devops/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/AzureDevOpsCli": {
       "types": "./src/server/AzureDevOpsCli.ts",
       "import": "./src/server/AzureDevOpsCli.ts"
diff --git a/packages/source-control-azure-devops/src/client/definition.ts b/packages/source-control-azure-devops/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..5b935c8925dcce2faef217c6f1e8b9a128a438b6
--- /dev/null
+++ b/packages/source-control-azure-devops/src/client/definition.ts
@@ -0,0 +1,33 @@
+/**
+ * Azure DevOps's client definition. Browser- and React Native-safe.
+ *
+ * @module source-control-azure-devops/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import { canonicalRepositoryKey } from "@t3tools/shared/sourceControl";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("azure-devops"),
+  label: "Azure DevOps",
+  pickerLabel: "Azure DevOps",
+  icon: "azure-devops",
+  changeRequest: { shortLabel: "PR", singular: "pull request" },
+  repositoryPathHint: "project/repository",
+  // `az repos` reads need the checkout's organization and project, so a bare hostname names no
+  // repository this client can act on.
+  publicHost: null,
+  publishDescription: "dev.azure.com",
+  publishHost: () => "dev.azure.com",
+  defaultCloneTransport: "ssh",
+  changeRequestUrl: ({ host, repository, number }) =>
+    `https://${canonicalRepositoryKey(`${host}/${repository}`.toLowerCase())}/pullrequest/${number}`,
+  checkoutCommand: ({ number }) => `az repos pr checkout --id ${number}`,
+  authorProfileUrl: () => null,
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: () => false,
+  isChangeRequestUrl: (url) => isChangeRequestPath(url, "/pullrequest/"),
+});
diff --git a/packages/source-control-bitbucket/package.json b/packages/source-control-bitbucket/package.json
index c878093ef54e260cd824130d42bdc5862cf1178f..890c4c34cbe5cbe9583bf4ff1fb0cf40ac4e82d7 100644
--- a/packages/source-control-bitbucket/package.json
+++ b/packages/source-control-bitbucket/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/BitbucketApi": {
       "types": "./src/server/BitbucketApi.ts",
       "import": "./src/server/BitbucketApi.ts"
diff --git a/packages/source-control-bitbucket/src/client/definition.ts b/packages/source-control-bitbucket/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..25010be99e938a31de2cffb89263956278e443da
--- /dev/null
+++ b/packages/source-control-bitbucket/src/client/definition.ts
@@ -0,0 +1,39 @@
+/**
+ * Bitbucket's client definition. Browser- and React Native-safe.
+ *
+ * @module source-control-bitbucket/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+const safeShellArgument = /^[A-Za-z0-9._/@+=,-]+$/;
+const repositoryName = /^[A-Za-z0-9._-]+\/[A-Za-z0-9._-]+$/;
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("bitbucket"),
+  label: "Bitbucket",
+  pickerLabel: "Bitbucket",
+  icon: "bitbucket",
+  changeRequest: { shortLabel: "PR", singular: "pull request" },
+  repositoryPathHint: "workspace/repository",
+  publicHost: "bitbucket.org",
+  publishDescription: "bitbucket.org",
+  publishHost: () => "bitbucket.org",
+  defaultCloneTransport: "ssh",
+  changeRequestUrl: ({ host, repository, number }) =>
+    `https://${host}/${repository}/pull-requests/${number}`,
+  // Bitbucket has no checkout CLI, so clone the head branch from its own repository.
+  checkoutCommand: ({ number, headBranch, headRepositoryNameWithOwner }) =>
+    headRepositoryNameWithOwner &&
+    repositoryName.test(headRepositoryNameWithOwner) &&
+    safeShellArgument.test(headBranch)
+      ? `git clone --single-branch --branch ${headBranch} https://bitbucket.org/${headRepositoryNameWithOwner}.git t3code-pr-${number}`
+      : null,
+  authorProfileUrl: () => null,
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: () => false,
+  isChangeRequestUrl: (url) => isChangeRequestPath(url, "/pull-requests/"),
+});
diff --git a/packages/source-control-core/package.json b/packages/source-control-core/package.json
index ee1045b278cd7abc1eb5b8473451f8a8a7de6b64..d463190918b2962f75d3b551561a0b34210327df 100644
--- a/packages/source-control-core/package.json
+++ b/packages/source-control-core/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/diffFileRevisions": {
       "types": "./src/server/diffFileRevisions.ts",
       "import": "./src/server/diffFileRevisions.ts"
diff --git a/packages/source-control-core/src/client/definition.ts b/packages/source-control-core/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..8db86cfcaf4dd20f504f7e3ac42e2b49edcdadc3
--- /dev/null
+++ b/packages/source-control-core/src/client/definition.ts
@@ -0,0 +1,166 @@
+/**
+ * The client half of a source control host package.
+ *
+ * Every host package exports a `SourceControlClientDefinition` from its `./client/definition`
+ * entry point, the way `./server/driver` is its server entry. Web, mobile, and client-runtime
+ * read labels, change request nouns, picker copy, and checkout commands from these definitions,
+ * so a new host needs no per-kind branches in client code.
+ *
+ * Definitions are browser- and React Native-safe: plain data and pure functions, no server or
+ * platform UI imports.
+ *
+ * @module source-control-core/client/definition
+ */
+import { type PullRequestReviewVerdict, SourceControlProviderKind } from "@t3tools/contracts";
+
+/** What a host calls a change request, e.g. `MR` and `merge request` on GitLab. */
+export interface ChangeRequestTerminology {
+  readonly shortLabel: string;
+  readonly singular: string;
+}
+
+/** Where a project's repository lives, for building its change request URLs. */
+export interface ChangeRequestUrlInput {
+  /** The host below which the repository is addressed, as `pullRequestHostOf` reports it. */
+  readonly host: string;
+  /** The repository path below the host. */
+  readonly repository: string;
+  readonly number: number;
+  /** The checkout's remote URL, whose origin some hosts serve their web pages from. */
+  readonly remoteUrl?: string | undefined;
+  /** The repository's browser URL, when the server resolved one from a hosting account. */
+  readonly webUrl?: string | undefined;
+}
+
+/** The change request a checkout command is built for. */
+export interface ChangeRequestCheckoutInput {
+  readonly number: number;
+  readonly headBranch: string;
+  readonly headRepositoryNameWithOwner?: string | null | undefined;
+  /** The repository's web URL, for hosts whose checkout fetches from it. */
+  readonly repositoryUrl?: string | null | undefined;
+}
+
+export interface SourceControlClientDefinition {
+  readonly kind: SourceControlProviderKind;
+  /** The host's name, as in "Open on GitHub". */
+  readonly label: string;
+  /** How the clone and publish pickers name the host; Forgejo's covers Gitea too. */
+  readonly pickerLabel: string;
+  /** Glyph key each client maps to its own icon; a key a client lacks draws the generic glyph. */
+  readonly icon: string;
+  readonly changeRequest: ChangeRequestTerminology;
+  /** Placeholder for a repository path on this host, such as `owner/repo`. */
+  readonly repositoryPathHint: string;
+  /**
+   * The hostname a change request reference can be attributed to before any repository
+   * identity is known, or null when a hostname alone does not name this host.
+   */
+  readonly publicHost: string | null;
+  /** Subtitle beside the host in the publish picker. */
+  readonly publishDescription: string;
+  /** Where a publish lands, given the host the server is signed in to, if it reported one. */
+  readonly publishHost: (signedInHost: string | null) => string;
+  /** Which of a repository's clone URLs a new clone uses. */
+  readonly defaultCloneTransport: "https" | "ssh";
+  /** The web URL of a change request, or null when this client cannot build one for the host. */
+  readonly changeRequestUrl: (input: ChangeRequestUrlInput) => string | null;
+  /** A shell command that checks the change request out, or null when it cannot be built. */
+  readonly checkoutCommand: (changeRequest: ChangeRequestCheckoutInput) => string | null;
+  /** A comment author's profile page, or null where the host has none clients can link. */
+  readonly authorProfileUrl: (login: string, repositoryUrl: string) => string | null;
+  /**
+   * The repository URL that `#123` and commit SHAs in change request text link under, using
+   * GitHub's `/issues/` and `/commit/` routes, or null where the host does not route them so.
+   */
+  readonly referenceAutolinkRepositoryUrl: (repositoryUrl: string) => string | null;
+  /** Whether a review with this verdict must carry a summary, beyond what every host asks. */
+  readonly reviewSummaryRequired: (verdict: PullRequestReviewVerdict) => boolean;
+  /** Whether a change request URL has this host's path shape, e.g. GitLab's `/-/merge_requests/`. */
+  readonly isChangeRequestUrl: (url: string) => boolean;
+}
+
+/**
+ * Whether a URL's path is a change request at `route`, such as `/pull/`, followed by its number.
+ * Matching the parsed path keeps a query or fragment that mentions another host's route out.
+ */
+export function isChangeRequestPath(url: string, route: string): boolean {
+  try {
+    const path = new URL(url).pathname;
+    const at = path.indexOf(route);
+    return at > 0 && /^\d+(?:\/|$)/u.test(path.slice(at + route.length));
+  } catch {
+    return false;
+  }
+}
+
+export function defineSourceControlClient<const Definition extends SourceControlClientDefinition>(
+  definition: Definition,
+): Definition {
+  return definition;
+}
+
+/** What clients show for a host they ship no definition for, including `unknown`. */
+const UNKNOWN_SOURCE_CONTROL_CLIENT: SourceControlClientDefinition = {
+  kind: SourceControlProviderKind.make("unknown"),
+  label: "source control",
+  pickerLabel: "source control",
+  icon: "change-request",
+  changeRequest: { shortLabel: "change request", singular: "change request" },
+  repositoryPathHint: "URL",
+  publicHost: null,
+  publishDescription: "Your signed-in server",
+  publishHost: (signedInHost) => signedInHost ?? "your server",
+  defaultCloneTransport: "ssh",
+  changeRequestUrl: () => null,
+  checkoutCommand: () => null,
+  authorProfileUrl: () => null,
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: () => false,
+  isChangeRequestUrl: () => false,
+};
+
+/** The host definitions a client loaded. */
+export interface SourceControlClientRegistry {
+  readonly definitions: ReadonlyArray<SourceControlClientDefinition>;
+  /**
+   * The definition for a kind. No kind at all, before a repository reports its host, reads as
+   * the first definition; a kind this client lacks, `unknown` included, reads as
+   * `UNKNOWN_SOURCE_CONTROL_CLIENT`.
+   */
+  readonly get: (kind: string | null | undefined) => SourceControlClientDefinition;
+  /** The definition for a kind, or `undefined` for one this client lacks. */
+  readonly find: (kind: string) => SourceControlClientDefinition | undefined;
+  /** The definition whose public instance is `hostname`, if any. */
+  readonly findByPublicHost: (hostname: string) => SourceControlClientDefinition | undefined;
+  /** The definition whose change request path shape `url` has, if any. */
+  readonly findByChangeRequestUrl: (url: string) => SourceControlClientDefinition | undefined;
+  /** The name of the host a change request URL is on, for copy about that change request. */
+  readonly hostLabelForChangeRequestUrl: (url: string) => string;
+}
+
+export function makeSourceControlClientRegistry(
+  definitions: ReadonlyArray<SourceControlClientDefinition>,
+): SourceControlClientRegistry {
+  const byKind = new Map<string, SourceControlClientDefinition>();
+  for (const definition of definitions) {
+    if (byKind.has(definition.kind)) {
+      throw new Error(`Source control host '${definition.kind}' is defined more than once.`);
+    }
+    byKind.set(definition.kind, definition);
+  }
+  return {
+    definitions,
+    get: (kind) =>
+      (kind == null ? definitions[0] : byKind.get(kind)) ?? UNKNOWN_SOURCE_CONTROL_CLIENT,
+    find: (kind) => byKind.get(kind),
+    findByPublicHost: (hostname) => {
+      const host = hostname.toLowerCase();
+      return definitions.find((definition) => definition.publicHost === host);
+    },
+    findByChangeRequestUrl: (url) =>
+      definitions.find((definition) => definition.isChangeRequestUrl(url)),
+    hostLabelForChangeRequestUrl: (url) =>
+      definitions.find((definition) => definition.isChangeRequestUrl(url))?.label ?? "the host",
+  };
+}
diff --git a/packages/source-control-forgejo/package.json b/packages/source-control-forgejo/package.json
index 4c6b534e2e81b4356a284be53796c5bdf8c918cb..a33de46a6de8a6c443ad9520e3f8599a46b3703c 100644
--- a/packages/source-control-forgejo/package.json
+++ b/packages/source-control-forgejo/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/driver": {
       "types": "./src/server/driver.ts",
       "import": "./src/server/driver.ts"
diff --git a/packages/source-control-forgejo/src/client/definition.ts b/packages/source-control-forgejo/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..aab19fcde22d694d960146fd5ffaf3f462435215
--- /dev/null
+++ b/packages/source-control-forgejo/src/client/definition.ts
@@ -0,0 +1,52 @@
+/**
+ * Forgejo's client definition, which covers Gitea as well. Browser- and React Native-safe.
+ *
+ * @module source-control-forgejo/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("forgejo"),
+  label: "Forgejo",
+  pickerLabel: "Forgejo / Gitea",
+  icon: "forgejo",
+  changeRequest: { shortLabel: "PR", singular: "pull request" },
+  repositoryPathHint: "owner/repo",
+  // Forgejo and Gitea are self-hosted, so no hostname names them.
+  publicHost: null,
+  publishDescription: "Your signed-in server",
+  publishHost: (signedInHost) => signedInHost ?? "your server",
+  defaultCloneTransport: "https",
+  // The server's resolved web URL wins; otherwise an HTTP remote on the same host names the
+  // origin, which may carry a port. SSH remotes say nothing about the web origin.
+  changeRequestUrl: ({ host, repository, number, remoteUrl, webUrl }) => {
+    if (webUrl) return `${webUrl.replace(/\/+$/, "")}/pulls/${number}`;
+    try {
+      const remote = new URL(remoteUrl ?? "");
+      if (
+        (remote.protocol === "http:" || remote.protocol === "https:") &&
+        (remote.hostname.toLowerCase() === host.toLowerCase() ||
+          remote.host.toLowerCase() === host.toLowerCase())
+      ) {
+        return `${remote.origin}/${repository}/pulls/${number}`;
+      }
+    } catch {
+      // Not an HTTP remote.
+    }
+    return `https://${host}/${repository}/pulls/${number}`;
+  },
+  // Neither `fj` nor `tea` checks out by number, so fetch the pull ref from the repository itself.
+  checkoutCommand: ({ number, repositoryUrl }) =>
+    repositoryUrl
+      ? `git fetch '${repositoryUrl.replaceAll("'", "'\\''")}' refs/pull/${number}/head && git checkout -B pulls/${number} FETCH_HEAD`
+      : null,
+  authorProfileUrl: () => null,
+  // Forgejo refuses a change request review without a summary, even with inline comments.
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: (verdict) => verdict === "request-changes",
+  isChangeRequestUrl: (url) => isChangeRequestPath(url, "/pulls/"),
+});
diff --git a/packages/source-control-gitcafe/package.json b/packages/source-control-gitcafe/package.json
index eeda68c5e92de81eae5ebc791785fc47bd88cd51..7107cd1e47f0e5af98bf8740f4abbe217d99dd3a 100644
--- a/packages/source-control-gitcafe/package.json
+++ b/packages/source-control-gitcafe/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/driver": {
       "types": "./src/server/driver.ts",
       "import": "./src/server/driver.ts"
diff --git a/packages/source-control-gitcafe/src/client/definition.ts b/packages/source-control-gitcafe/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..6407d57828d10d9e46ff7d5acb014c7d095af89c
--- /dev/null
+++ b/packages/source-control-gitcafe/src/client/definition.ts
@@ -0,0 +1,45 @@
+/**
+ * GitCafe's client definition. Browser- and React Native-safe.
+ *
+ * @module source-control-gitcafe/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+/** GitCafe has no self-hosted installs: production and staging are its only hosts. */
+const GITCAFE_HOSTS = new Set(["git.cafe", "staging.git.cafe"]);
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("gitcafe"),
+  label: "GitCafe",
+  pickerLabel: "GitCafe",
+  icon: "gitcafe",
+  changeRequest: { shortLabel: "PR", singular: "pull request" },
+  repositoryPathHint: "owner/repo",
+  // Left unattributed so a reference with no repository identity behind it gets no checkout
+  // command guessed from its hostname alone.
+  publicHost: null,
+  publishDescription: "git.cafe",
+  publishHost: () => "git.cafe",
+  defaultCloneTransport: "ssh",
+  changeRequestUrl: ({ host, repository, number }) =>
+    `https://${host}/${repository}/pulls/${number}`,
+  checkoutCommand: ({ number }) => `cafe pr checkout ${number}`,
+  authorProfileUrl: () => null,
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: () => false,
+  // `/pulls/` is Forgejo's shape too, so only GitCafe's own hosts claim it.
+  isChangeRequestUrl: (url) => {
+    try {
+      return (
+        GITCAFE_HOSTS.has(new URL(url).hostname.toLowerCase()) &&
+        isChangeRequestPath(url, "/pulls/")
+      );
+    } catch {
+      return false;
+    }
+  },
+});
diff --git a/packages/source-control-github/package.json b/packages/source-control-github/package.json
index 46a8965976fd32098b969578cb4c37ace3a48f7d..7cd6bed31b83bd60ad07bd7c8860d7b705020794 100644
--- a/packages/source-control-github/package.json
+++ b/packages/source-control-github/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/driver": {
       "types": "./src/server/driver.ts",
       "import": "./src/server/driver.ts"
diff --git a/packages/source-control-github/src/client/definition.ts b/packages/source-control-github/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..fe79b7f91cc358ab4e20ab5394c91554ed705fbf
--- /dev/null
+++ b/packages/source-control-github/src/client/definition.ts
@@ -0,0 +1,33 @@
+/**
+ * GitHub's client definition. Browser- and React Native-safe.
+ *
+ * @module source-control-github/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("github"),
+  label: "GitHub",
+  pickerLabel: "GitHub",
+  icon: "github",
+  changeRequest: { shortLabel: "PR", singular: "pull request" },
+  repositoryPathHint: "owner/repo",
+  publicHost: "github.com",
+  publishDescription: "github.com",
+  publishHost: () => "github.com",
+  defaultCloneTransport: "https",
+  changeRequestUrl: ({ host, repository, number }) =>
+    `https://${host}/${repository}/pull/${number}`,
+  checkoutCommand: ({ number }) => `gh pr checkout ${number}`,
+  authorProfileUrl: (login, repositoryUrl) =>
+    login.endsWith("[bot]")
+      ? null
+      : new URL(`/${encodeURIComponent(login)}`, repositoryUrl).toString(),
+  referenceAutolinkRepositoryUrl: (repositoryUrl) => repositoryUrl,
+  reviewSummaryRequired: () => false,
+  isChangeRequestUrl: (url) => isChangeRequestPath(url, "/pull/"),
+});
diff --git a/packages/source-control-gitlab/package.json b/packages/source-control-gitlab/package.json
index 6b99c878ccb83317db3948096ccb117a308765df..def5c117c558c6484c64c9af263a179706f5c2b0 100644
--- a/packages/source-control-gitlab/package.json
+++ b/packages/source-control-gitlab/package.json
@@ -3,6 +3,10 @@
   "private": true,
   "type": "module",
   "exports": {
+    "./client/definition": {
+      "types": "./src/client/definition.ts",
+      "import": "./src/client/definition.ts"
+    },
     "./server/driver": {
       "types": "./src/server/driver.ts",
       "import": "./src/server/driver.ts"
diff --git a/packages/source-control-gitlab/src/client/definition.ts b/packages/source-control-gitlab/src/client/definition.ts
new file mode 100644
index 0000000000000000000000000000000000000000..23c88b1b6d2fd60ffbddf8cb4f3bdc1faf9bb492
--- /dev/null
+++ b/packages/source-control-gitlab/src/client/definition.ts
@@ -0,0 +1,30 @@
+/**
+ * GitLab's client definition. Browser- and React Native-safe.
+ *
+ * @module source-control-gitlab/client/definition
+ */
+import { SourceControlProviderKind } from "@t3tools/contracts";
+import {
+  defineSourceControlClient,
+  isChangeRequestPath,
+} from "@t3tools/source-control-core/client/definition";
+
+export const definition = defineSourceControlClient({
+  kind: SourceControlProviderKind.make("gitlab"),
+  label: "GitLab",
+  pickerLabel: "GitLab",
+  icon: "gitlab",
+  changeRequest: { shortLabel: "MR", singular: "merge request" },
+  repositoryPathHint: "group/project",
+  publicHost: "gitlab.com",
+  publishDescription: "gitlab.com",
+  publishHost: () => "gitlab.com",
+  defaultCloneTransport: "ssh",
+  changeRequestUrl: ({ host, repository, number }) =>
+    `https://${host}/${repository}/-/merge_requests/${number}`,
+  checkoutCommand: ({ number }) => `glab mr checkout ${number}`,
+  authorProfileUrl: () => null,
+  referenceAutolinkRepositoryUrl: () => null,
+  reviewSummaryRequired: () => false,
+  isChangeRequestUrl: (url) => isChangeRequestPath(url, "/-/merge_requests/"),
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 249f45a453cc958c2961f4476ff64d5984e9fd2b..dcd65d4ce34ee9a72cf4d73d1a9ef41516832337 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1078,6 +1078,27 @@ importers:
       '@t3tools/shared':
         specifier: workspace:*
         version: link:../shared
+      '@t3tools/source-control-azure-devops':
+        specifier: workspace:*
+        version: link:../source-control-azure-devops
+      '@t3tools/source-control-bitbucket':
+        specifier: workspace:*
+        version: link:../source-control-bitbucket
+      '@t3tools/source-control-core':
+        specifier: workspace:*
+        version: link:../source-control-core
+      '@t3tools/source-control-forgejo':
+        specifier: workspace:*
+        version: link:../source-control-forgejo
+      '@t3tools/source-control-gitcafe':
+        specifier: workspace:*
+        version: link:../source-control-gitcafe
+      '@t3tools/source-control-github':
+        specifier: workspace:*
+        version: link:../source-control-github
+      '@t3tools/source-control-gitlab':
+        specifier: workspace:*
+        version: link:../source-control-gitlab
       effect:
         specifier: 4.0.2
         version: 4.0.2(patch_hash=ec61ee307eaec3e17f757e0e6a16296ea4b7a8c3188df0c6ec5e66301fd78688)