fix(feeds): handle null comment user in gh-sync content builder

[norrietaylor]

Root cause

GitHub's REST API returns "user": null for issue/PR comments authored by deleted or ghost accounts. In _build_content (src/distillery/feeds/github_sync.py), the comment author was read with:

author = comment.get("user", {}).get("login", "unknown")

dict.get("user", {}) only returns the {} default when the key is absent. When the key is present with a null/None value, it returns None, so None.get("login", ...) raises AttributeError. This propagated out of _build_content → _issue_to_entry, crashing the sync for the affected issue/PR (both sync() and sync_batched() paths).

Fix

Coerce a missing or null user object to an empty dict before the lookup:

user = comment.get("user") or {}
author = user.get("login", "unknown")

Comments from ghost accounts now attribute to "unknown" instead of aborting the sync. Surgical one-line change plus a clarifying comment.

Acceptance

• New unit test TestBuildContent::test_comment_with_null_user reproduces the crash (fails with AttributeError before the fix) and passes after.
• Full tests/test_github_sync.py and tests/test_feeds.py suites pass (171 tests).
• ruff check and mypy --strict clean on the touched source file.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved GitHub comment rendering to properly handle comments from deleted or ghosted user accounts, now displaying "unknown" as the author instead of potential errors.

• Tests

  • Added test coverage for comments from deleted GitHub user accounts.

[coderabbitai]

Complex PR? Review this PR in Change Stack to move by importance, not file order.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 15b9b826-a089-41ec-9a88-324b0a80c0c3

📥 Commits

Reviewing files that changed from the base of the PR and between 5a437a2 and cd50767.

📒 Files selected for processing (2)

• src/distillery/feeds/github_sync.py
• tests/test_github_sync.py

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📝 Walkthrough

Walkthrough

This PR fixes a robustness issue in GitHub comment rendering where the API returns "user": null for deleted or ghost accounts. The fix normalizes null user fields to empty dicts before extracting login information, ensuring the "unknown" author fallback works reliably. A new test verifies the behavior for both null and valid user cases.

Changes

Null user handling in GitHub comments

Layer / File(s)	Summary
Comment rendering with null user fallback src/distillery/feeds/github_sync.py, tests/test_github_sync.py	_build_content normalizes potentially-null GitHub comment user fields to empty dicts before extracting login, ensuring the "unknown" author fallback works for deleted/ghost accounts. Test added for null user case alongside existing valid user login behavior.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• norrietaylor/distillery#305: Both PRs modify GitHub sync author handling to cope with user: null payloads (main PR in github_sync.py comment rendering via _build_content, retrieved PR in github_sync.py issue/PR entry author derivation), so they are directly related at the GitHub "null user" edge-case level.

Poem

🐰 A comment with no user to claim,
Ghost accounts left with no name—
We normalize the null with care,
So "unknown" renders fair and square!
A simple fix, but oh so grand,
For deleted users understand. ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing handling of null comment users in the GitHub sync content builder, which is the core fix addressing the AttributeError crash.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

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