Fence info strings were compared verbatim against the supported language list, so `\`\`\`js`, `\`\`\`py`, `\`\`\`sh`, and any-case variants like `\`\`\`Python` got no highlighting. `get_language_name_for_info_string()` and `MARKDOWN_INFO_STRING_LANGUAGES` existed for exactly this purpose but had no callers. Injection languages that fail the supported language check are now resolved through the alias table first. This also changes when `highlight()` returns None (meaning "fall back to another highlighter"). It used to return `None` when the file-level captures came up empty, before processing injections. That check was order-dependent: the capture list shrinks as `HIGHLIGHT_IGNORE` grows at runtime, so a Markdown file containing only fenced code could lose all highlighting depending on what had been highlighted earlier in the process. `highlight()` now returns `None` exactly when no capture produced a highlight span, after injections are collected. This is deterministic and lets files that tree-sitter cannot style (such as Markdown inline emphasis, which has no mapped highlight classes) fall back to Pygments. Testing Done: - Added parametrized tests for aliased fence info strings, which also cover the order-dependent early return (the parametrized runs share a process). - Ran all tests.