Function doc-headers are authored as plain text -- `config-help`, `funcsave` and anyone opening the `.fish` file read them as-is -- so they carry no backticks. The site inherited that and rendered `-a/--all` and `__fish_config_op_aliases` as ordinary prose. docs/codespans.py adds the spans at render time, as the last step of prettify(), so only the site sees them; build_concat() (man page, config-help) is byte-for-byte unchanged. Recognised shapes: flags and flag pairs, `$vars`, SCREAMING_SNAKE env vars, snake_case identifiers, paths and filenames, key chords, command shadow chains (`ls->eza`), runs of tool names, whole command lines in a table column of command lines, and known command names -- drawn from the `_fdc_*` catalog in functions/_fish_deps_catalog.fish, the functions/ listing, and a standard-command list, minus the names that also read as English. Fenced blocks, existing code spans, headings, link targets, URLs, component markup and <FileTree> bodies are passed through untouched, and every rule bails out rather than guess.