Add GitHub PR diff context to changelog

[redreceipt]

Summary

• fetch PR diffs through new get_pr_diff helper
• collect linked PR diffs for issues in post_weekly_changelog
• include diff content in chunks sent to OpenAI so the summary has more detail

Testing

• flake8 github.py jobs.py linear/*.py
• python -m py_compile github.py jobs.py linear/*.py openai_client.py config.py

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https://chatgpt.com/codex/tasks/task_e_688bc5cc0f608324b13311dcccc98198

[Copilot]

Pull Request Overview

This PR enhances the weekly changelog generation by incorporating GitHub PR diff content to provide more detailed summaries. The change allows the system to fetch PR diffs for issues with linked GitHub PRs and include this diff information as additional context when generating OpenAI summaries.

Key changes:

• Added GitHub REST API integration to fetch PR diffs
• Enhanced changelog issue processing to extract and include PR diff content
• Updated OpenAI prompt instructions to utilize diff context for better summaries

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
github.py	Added get_pr_diff function and REST API configuration for fetching PR diffs
jobs.py	Added _get_pr_diffs helper function and integrated diff content into changelog chunks

Comments suppressed due to low confidence (1)

github.py:27

• The GitHub API version '2022-11-28' appears to be outdated. Consider using a more recent stable version like '2022-11-28' was the latest stable version as of my knowledge cutoff, but newer versions may be available.

    "X-GitHub-Api-Version": "2022-11-28",

[Copilot]

Catching a broad Exception is too generic. Consider catching more specific exceptions like requests.RequestException or requests.HTTPError to handle network-related errors more precisely.

Suggested change

	except Exception as e: # pragma: no cover - network errors are ignored
	except requests.RequestException as e: # pragma: no cover - network errors are ignored

[Copilot]

Multiple string concatenations could be inefficient for large diffs. Consider using a single join operation: chunk_parts.append(f"Diff:\n{chr(10).join(diffs)}")

Suggested change

	chunk_parts.append("Diff:\n" + "\n".join(diffs))
	chunk_parts.append(f"Diff:\n{chr(10).join(diffs)}")