Before this change, the inline markdown parser greedily matched the
underscore in identifiers like `deepseek_tui` or `foo_bar_baz` against
the `_italic_` pattern, so the second half of the identifier rendered
in italic and transcript snippets that quoted code symbols read as
garbled prose. The same bug applied to `*italic*` against tokens like
`look_at*tail`.
Both italic delimiters now apply a CommonMark-style boundary check on
the closing run: when the character immediately after the closing
`_` / `*` is a letter, digit, or underscore, the delimiter is left
as literal text rather than treated as markup. Identifiers survive
intact; legitimate emphasis still renders.
Regression-pinned with `crate deepseek_tui handles approvals`,
`see foo_bar_baz for details`, and `look at *not_emphasised*tail`.
Harvested from PR #1455 by @tiger-dog
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Hunter Bown
02f889f193