rust-serdelisted

Use when you derive Serialize or Deserialize on a type whose encoded form is a contract - a config file, an on-disk record, a cached payload, a message another process or an older build reads. Covers deny_unknown_fields and the rename_all migration trap, the four enum representations and what each puts on the wire, why untagged destroys error messages, flatten and its interaction with deny_unknown_fields and non-self-describing formats, validation at the boundary with try_from, and the default plus alias pair that keeps old and new payloads both readable. Triggers on serde, Serialize, Deserialize, serde_json, deny_unknown_fields, rename_all, serde(tag), untagged, serde(flatten), skip_serializing_if, serde(default), serde(alias), serde(try_from), "unknown field", "did not match any variant", or any wire-compatibility question.
po4yka/rust-skills · ★ 2 · AI & Automation · score 76

Install: claude install-skill po4yka/rust-skills

# Rust serde ## Purpose Rules for types whose encoded form other code depends on. A `#[derive(Deserialize)]` is a parser and a published schema at the same time, and the derive hides that. Most serde incidents are not crashes; they are a field that silently stayed at its default, or a payload an older build can no longer read. Find what is at stake before you change a type: ```bash # Every type whose encoding is a contract with something outside this process. rg -n '#\[derive\([^)]*Deserialize' --type rust # Attributes that change the wire format. Each one is a compatibility decision. rg -n '#\[serde\((rename|rename_all|tag|untagged|flatten|skip)' --type rust # Structs that accept anything they are given. rg -L 'deny_unknown_fields' -l --type rust $(rg -l 'Deserialize' --type rust) ``` ## Decide what the encoding is for | The encoded form is | Rule | | --- | --- | | Internal to one process, one build, cache that may be discarded | Change it freely. Version the cache directory and drop it on mismatch | | Written by a human: config, manifest, fixture | `deny_unknown_fields`. A typo must be an error, not a default | | Read by an older build of your own code | Additive only. Every new field gets `default` | | Read by another team or another language | Additive only, plus an explicit version field and a written schema | The second and third rows conflict: `deny_unknown_fields` rejects a field a *newer* writer added. Apply it to files a human authors, not to messages a new