merge-ruff-120

name	merge-ruff-120
description	Reformat code on a feature branch and merge main cleanly after the Ruff line-length increase from 79 to 120 (merged August 7, 2026, commit 0110bb1d273dbe848312d429326b844da9e86d93, PR #5514). Relevant for branches created before August 2026.

Merging main and Reformatting Code (Ruff 120 Line Length)

Overview

In PR #5514 (merged on August 7, 2026, commit 0110bb1d273dbe848312d429326b844da9e86d93), OpenTelemetry Python updated its Ruff configuration in pyproject.toml to increase line-length from 79 to 120 characters and reformatted the entire codebase.

Feature branches created prior to August 7, 2026 (before this commit) will encounter extensive merge conflicts if merged directly. This skill instructs an agent on how to detect this situation and perform a clean multi-step merge without formatting conflict markers.

Detection: When to Use This Skill

An agent can test whether a branch needs this reformatting workflow:

# Returns non-zero (exit code 1) if the branch was created BEFORE the Ruff 120 change (August 7, 2026):
git merge-base --is-ancestor 0110bb1d273dbe848312d429326b844da9e86d93 HEAD

If the commit is not an ancestor of HEAD, follow the workflow below.

---

Workflow

Follow these steps on the contributor's feature branch:

Step 1: Identify upstream remote, ensure workspace is clean & sync dependencies

First, inspect configured remotes to identify which remote points to the upstream open-telemetry/opentelemetry-python repository (typically upstream or origin):

git remote -v

Note: In a fork-based workflow, upstream typically points to open-telemetry/opentelemetry-python and origin points to the contributor's fork. In direct clones, origin points to open-telemetry/opentelemetry-python. In the steps below, replace <remote> with the name of the remote pointing to open-telemetry/opentelemetry-python (e.g., upstream or origin).

Fetch latest changes and sync dependencies:

uv sync --frozen --all-packages
git fetch <remote> main

Step 2: Merge the commit before the line-length change

Merge all changes up to the commit immediately before the Ruff 120 reformat:

git merge 0110bb1d273dbe848312d429326b844da9e86d93^

Because both sides are still 79-column code, there are zero formatting conflicts. Resolve any real semantic conflicts if present, then commit the merge.

Step 3: Merge the reformatting commit with -X ours --no-commit

Merge the reformat commit, automatically choosing the branch's code on any formatting conflicts and pausing before creating the merge commit:

git merge -X ours --no-commit 0110bb1d273dbe848312d429326b844da9e86d93

Step 4: Format and lint the branch to 120 columns

Ensure pyproject.toml has line-length = 120 (under [tool.ruff]). Use file editing tools or Python to avoid macOS vs Linux sed -i incompatibilities:

python3 -c "import pathlib; p = pathlib.Path('pyproject.toml'); p.write_text(p.read_text().replace('line-length = 79', 'line-length = 120'))"
uv run ruff format
uv run ruff check --fix

Step 5: Finalize the merge commit

git commit -am "chore: merge Ruff 120 reformat and format branch"

Step 6: Catch up with latest main

Merge the rest of main from the upstream remote:

git merge <remote>/main