Add minimal pre-commit config

.pre-commit-config.yaml

@@ -0,0 +1,41 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v6.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-toml
+      - id: check-merge-conflict
+      - id: check-vcs-permalinks
+      - id: check-executables-have-shebangs
+      - id: mixed-line-ending
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.15.6
+    hooks:
+      - id: ruff-format
+        types_or: [python, pyi]
+  - repo: https://github.com/pre-commit/mirrors-clang-format
+    rev: v22.1.1
+    hooks:
+      - id: clang-format
+        types_or: [c++, c, cuda]
+  - repo: https://github.com/BlankSpruce/gersemi
+    rev: 0.26.0
+    hooks:
+      - id: gersemi
+  - repo: https://github.com/google/go-jsonnet
+    rev: v0.21.0
+    hooks:
+      - id: jsonnet-format
+      - id: jsonnet-lint
+        # The files in test/max-parallelism import files that are generated during the build.
+        # We therefore exclude them from linting, but still format them.
+        exclude: ^test/max-parallelism
+  - repo: https://github.com/rbubley/mirrors-prettier
+    rev: v3.8.1
+    hooks:
+      - id: prettier
+        types_or: [yaml]

DEVELOPING.md

@@ -122,3 +122,19 @@ The `.github/copilot-instructions.md` contains various "ground rules" to be obse
 The instructions in this file were created not by hand, but by asking Copilot to produce instructions for itself to achieve a goal, such as, "Please update the instructions file to ensure adherence to `markdown-lint` rules when generating Markdown files." This way (hopefully), the instructions are more likely to have the intended effect on the AI since they were generated by the AI itself.
 
 If you wish to add your own personalized instructions, or adjust/augment the repository-level instructions via PR, best results will be achieved by following this method rather than writing them yourself except in the most trivial of cases.
+
+## Pre-commit
+
+The tool pre-commit offers a framework for setting up hooks that are run on staged files before committing, ensuring correct formatting and catching some errors before they end up in a commit.
+
+To set up this tool locally, first install `pre-commit` (or `prek`, a faster re-implementation in rust) using your system package manager or `uv`/`pip(x)`, e.g. `uv tool install pre-commit`.
+
+So set up the hooks in the Phlex repository, run the `pre-commit install` command once in the repository. The hooks now should run automatically prior to each commit.
+
+To skip a check temporarily, run `SKIP=ruff-format git commit -m "...". To skip all hooks, you can use the `--no-verify` flag to `git commit`.
+
+To manually run hooks over all files, run `pre-commit run --all-files`.
+
+The pre-commit hooks are configured in `.pre-commit-config.yaml`.
+
+For further reference, see the extensive [pre-commit documentation](https://pre-commit.com/).