`preserveFrontmatterOrder` config flag is accepted but silently ignored

[mayashavin]

Problem

polira.config.ts accepts markdown.preserveFrontmatterOrder: true (default) as a documented configuration option (src/core/config.ts:47). However, src/utils/frontmatter.ts:29 calls matter.stringify(body, frontmatter) with no key-ordering logic.

gray-matter's stringify does not guarantee key order; it serialises frontmatter as a plain object, so existing frontmatter field order is not preserved when updateFrontmatterTool writes changes.

Expected behaviour

When preserveFrontmatterOrder: true (the default), stringifyFrontmatter should reconstruct the YAML block with original key order intact, inserting new fields at the end.

When preserveFrontmatterOrder: false, the current behaviour (arbitrary serialisation order) is acceptable.

Files affected

• src/utils/frontmatter.ts — stringifyFrontmatter function
• src/tools/update-frontmatter/updateFrontmatterTool.ts
• src/core/config.ts — config schema entry

Suggestion

Preserve the original key order by building the updated frontmatter object with original keys first, then appending new keys. Pass that ordered object to matter.stringify.