fix: parse_inline drops links at position 0 and marks() loses href

[ASRagab]

Summary

Two bugs in inline link handling that cause all links created via from_markdown() to have null hrefs, and links at the start of a line to be silently dropped.

Bug 1: Links at position 0 are dropped

parse_inline() skips links that start at position 0 in the text. The image-exclusion check:

if match.start() > 0 and text[match.start()-1:match.start()+1] != "![":

Short-circuits to False when match.start() == 0, causing the link to be skipped entirely.

Fix: Check match.start() == 0 or text[match.start() - 1] != "!" instead.

Repro:

parse_inline('[GPT](https://openai.com/)')
# Before: [{'content': '[GPT](https://openai.com/)'}]  # raw text, not a link
# After:  [{'content': 'GPT', 'marks': [{'type': 'link', 'attrs': {'href': 'https://openai.com/'}}]}]

Bug 2: All link hrefs are null

parse_inline() returns marks with the structure {'type': 'link', 'attrs': {'href': url}}, but marks() reads from mark.get('href') at the top level — missing the nested attrs entirely.

Fix: Fall back to mark.get('attrs', {}).get('href') when top-level href is not present. This preserves backward compatibility with the top-level format shown in the README examples.

Repro:

post = Post('Test', '', user_id=1)
post.from_markdown('Visit [Example](https://example.com)')
body = json.loads(post.get_draft()['draft_body'])
# Before: href is null for all links
# After:  href is 'https://example.com'

Tests

Added tests/substack/test_post.py with 6 tests covering:

• Links at position 0
• Multiple links on same line
• Image exclusion (not parsed as link)
• Links in middle of text
• href from attrs (from_markdown path)
• href from top-level (manual add path)

All tests pass. Pre-commit hooks (black, isort, trailing-whitespace, end-of-file-fixer) all pass.

[ma2za]

hi, thank you for the contribution... can you remove all the formatting changes please? they make it hard to review

[ASRagab]

Done — I reverted the formatting-only changes so the diff is now just the two functional fixes (position-0 links + link href in marks) plus the new regression tests. Sorry about the noise earlier (there's still hidden whitespace it's removing).