MEDIA_TAG_CLEANUP_RE failed to match when a directive like [[as_document]]
was concatenated directly to the file extension without whitespace
(e.g., MEDIA:/home/user/report.xlsx[[as_document]]). This caused the
file to be silently not delivered while the gateway reported success.
Root cause: the lookahead character class [\s`",;:)\}\]|$) did not
include [, so [[as_document]] immediately after the extension broke
the lookahead assertion.
Fix: add \[ to the lookahead class so directives can follow the path
without whitespace. This is safe because [ is already stripped elsewhere
in the same file via .replace("[[as_document]]", "").
Added regression tests covering:
- Directive glued to extension (issue case)
- Directive with whitespace (baseline)
- Tag at end of string ($ anchor)
liuhao1024
b58b1fa962