🐛 fix(markdown): preserve links after bangs

[gaborbernat]

to_markdown() turns !<a href="/x">x</a> into ![x](/x), which CommonMark reads as an image instead of a literal ! followed by a link. CommonMark 6.4, Example 593 gives \![x](/x) for this case.

Fix

Escape a live ! only when the next emitted marker opens a link. This also covers empty and reference-style links while leaving spaces and already escaped punctuation alone. Escaping only ! keeps the link in ordinary Markdown and avoids a raw HTML fallback for valid link syntax. Single-byte marker opens use a direct append, keeping normal Markdown rendering below the prior instruction count.

Turbohtml: literal ! and link preserved. The before and after files below contain the exact to_markdown() output for the same input. This hunk comes from git diff --no-index --unified=0:

diff --git a/before.md b/after.md
index 77cdcb9..671a6d1 100644
--- a/before.md
+++ b/after.md
@@ -1 +1 @@
-![x](/x)
\ No newline at end of file
+\![x](/x)
\ No newline at end of file

Competitors

markdownify 1.2.3 and html2text 2025.4.15: image instead of link

markdownify output:

diff --git a/after.md b/markdownify.md
index 671a6d1..77cdcb9 100644
--- a/after.md
+++ b/markdownify.md
@@ -1 +1 @@
-\![x](/x)
\ No newline at end of file
+![x](/x)
\ No newline at end of file

markdownify emits ![x](/x), which md4c and markdown-it-py parse as an image. The source has a literal exclamation mark followed by a link, so we escape !.

html2text output:

diff --git a/after.md b/html2text.md
index 671a6d1..9541679 100644
--- a/after.md
+++ b/html2text.md
@@ -1 +1,2 @@
-\![x](/x)
\ No newline at end of file
+![x](/x)
+

html2text produces the same image syntax with an extra blank line. The blank line does not change the parse; the escaped ! form preserves the source structure and follows CommonMark Example 593.

Performance

On CPython 3.15.0 with GCC 16.2.1, Valgrind Callgrind 3.27.1, and a fixed hash seed, 20,000 representative Markdown renders changed from 221,941,063 to 221,561,063 instructions (−0.17%). A five-link paragraph changed from 255,841,056 to 253,921,056 (−0.75%).

[codspeed]

Merging this PR will not alter performance

✅ 582 untouched benchmarks
⏩ 32 skipped benchmarks¹

---

_{Comparing gaborbernat:fix/markdown-bang-link (38cf8ed) with main (d4701ec)}

Footnotes

1. 32 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩