Renovate per crate updates (#1241)

The renovate pull requests are [getting out of
control](#1208). This change
splits up the pull requests to be per-crate rather than to be one big
one for the whole project. Each individual crate will tag the respective
code owners of that crate for review.

This will result in more, but better scoped pull requests which can
hopefully be more easily merged outright rather than one massive almost
always broken pull request which needs human / LLM fixing before
merging.

Author: 1egoman

renovate.json

@@ -4,17 +4,13 @@
   "minimumReleaseAge": "2 weeks",
   "commitBody": "Generated by renovateBot",
   "schedule": ["before 9am on the first day of the month"],
+  "reviewersFromCodeOwners": true,
   "packageRules": [
     {
       "matchManagers": ["github-actions"],
       "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
       "groupName": "github actions"
     },
-    {
-      "matchManagers": ["cargo"],
-      "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
-      "groupName": "cargo dependencies"
-    },
     {
       "matchManagers": ["npm"],
       "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
@@ -29,6 +25,19 @@
       "matchManagers": ["gradle", "gradle-wrapper"],
       "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
       "groupName": "gradle dependencies"
+    },
+    {
+      "description": "Split cargo updates into one PR per crate (per package-file directory) so PRs stay small and only tag the relevant codeowners.",
+      "matchManagers": ["cargo"],
+      "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
+      "groupName": "cargo dependencies ({{{packageFileDir}}})"
+    },
+    {
+      "description": "Updates to the root workspace manifest (shared [workspace.dependencies]) get their own PR.",
+      "matchManagers": ["cargo"],
+      "matchUpdateTypes": ["minor", "patch", "digest", "pin"],
+      "matchFileNames": ["Cargo.toml"],
+      "groupName": "cargo workspace dependencies"
     }
   ]
 }