`publish` appends `atUri` at EOF, corrupting TOML frontmatter when a table precedes it (key gets nested into the table) #46

Version: sequoia-cli 0.5.7

Environment: Hugo blog, TOML frontmatter (+++ delimiters), posts with a [cover] table.

Summary #

sequoia publish writes the atUri back to a post's frontmatter as a new line at the end of the frontmatter block. In TOML, a bare key after a [table] header belongs to that table — it does not return to the top level. So when frontmatter contains any table (e.g. PaperMod's [cover]), the appended atUri is parsed as a key inside that table rather than a top-level key. Downstream consumers that read top-level atUri (templates, the inject step, social cards) then see it as missing.

Steps to reproduce #

1. A post with TOML frontmatter that ends with a table:

   +++
   title = "Example"
   coverImage = "static/covers/example.png"
   
   [cover]
     image = "/covers/example.png"
     alt = "…"
     hidden = true
   +++
   

2. Run sequoia publish.

Actual result #

atUri is appended after the table, so it parses as cover.atUri:

   [cover]
     image = "/covers/example.png"
     alt = "…"
     hidden = true
   atUri = "at://did:plc:…/site.standard.document/…"   # ← nested under [cover]
   +++

Top-level atUri is empty. Any template/logic gating on it silently no-ops, with no error.

Expected result #

atUri should be written as a top-level key regardless of existing tables — e.g. inserted before the first table header, or set via a structure-aware TOML edit rather than a raw line append.

Impact #

• Silent: no parse error, no warning. The post publishes to ATproto fine, but anything keying off frontmatter atUri (e.g. rendering a recommend/subscribe component, conditional logic, the inject correlation) breaks.
• Affects every post whose frontmatter has a table before EOF. Posts with no table (flat frontmatter) are unaffected, which makes it look intermittent and hard to spot.
• Symmetric risk for any future appended key, and likely the same in YAML/JSON frontmatter if the append isn't format-aware (the table-nesting failure is TOML-specific, but EOF-appending is fragile in general).

Suggested fix #

Parse the frontmatter into a structured document and set atUri as a top-level field, then re-serialize — instead of appending a raw line. If a lightweight approach is preferred, at minimum insert the key before the first [table]/[[array]] header within the frontmatter block.

Workaround #

Manually move the atUri line above any table header in the frontmatter (keeps it top-level), or express the table as a TOML inline table so there is no open table section for an appended key to fall into:

cover = { image = "/covers/example.png", alt = "…", hidden = true }
atUri = "at://…"   # appended at EOF, stays top-level