chore(rfc): wrap markdown at 120 columns and add RFC style rules to the rfc skill

.claude/skills/rfc/SKILL.md

@@ -7,34 +7,70 @@ context: fork
 
 # RFC
 
-Write a 1-2 page RFC. It exists to get agreement on an approach, not to specify it:
-details are the implementer's call and need no prior approval here.
+Write a 1-2 page RFC. It exists to get agreement on an approach, not to specify it: details are the implementer's call
+and need no prior approval here.
 
 ## Mechanics
 
-- File `docs/rfcs/<kebab-title>.md` from
-  [docs/rfcs/0001-template.md](../../../docs/rfcs/0001-template.md). **Do not number it**
-  and **do not touch `_index.md`** — `number-rfc.yml` assigns the number on merge to
-  `main` and rebuilds the index from the files on disk.
-- Keep the H1 as `# RFC — Title`, em dash included; the numbering step rewrites that
-  exact form to inject the number.
-- Set `status: draft` in the frontmatter. Omitting it makes CI index the RFC as
-  `accepted`.
-- `check-rfc.yml` reads the document: a new RFC needs `title` and `owner` in its
-  frontmatter, a `## Summary`, a `## Motivation`, and a section covering the
-  approach, and no draft may keep unedited template text or a `TODO`. Rust
+- File `docs/rfcs/<kebab-title>.md` from [docs/rfcs/0001-template.md](../../../docs/rfcs/0001-template.md). **Do not
+  number it** and **do not touch `_index.md`** — `number-rfc.yml` assigns the number on merge to `main` and rebuilds the
+  index from the files on disk.
+- Keep the H1 as `# RFC — Title`, em dash included; the numbering step rewrites that exact form to inject the number.
+- Set `status: draft` in the frontmatter. Omitting it makes CI index the RFC as `accepted`.
+- `check-rfc.yml` reads the document: a new RFC needs `title` and `owner` in its frontmatter, a `## Summary`, a
+  `## Motivation`, and a section covering the approach, and no draft may keep unedited template text or a `TODO`. Rust
   changes are not required in the same PR.
 
 ## Writing it
 
 - Lead with the problem. If it isn't concrete, the RFC isn't ready.
 - Describe what changes and why, not signatures, thresholds or edge cases.
 - Cut every sentence that would not change a reader's mind.
-- Prefer a stated assumption to a blocking question. Ask the author only when the
-  answer changes the approach.
+- Prefer a stated assumption to a blocking question. Ask the author only when the answer changes the approach.
 - Omit any section you would otherwise fill for the template's sake.
 
+## Style
+
+Rules for writing and reviewing RFCs and design documents in this repository. An RFC is a strict proposal, not an essay:
+it states what the system does, and nothing else.
+
+### Cut
+
+- Selling text and justification. State the rule; drop the reasoning and the "why this is good".
+- Enumerations of examples. One case or none.
+- Em-dash appositions and dash-appended lists. Use plain sentences, a colon, or "because" and "so".
+- Bold-lead paragraphs that act as mini-sections. Fold them into the surrounding text or make a real heading.
+- Self-references: "this RFC", "this section", "below", "above", "stated under X".
+- Transition narrative: "previously X, now Y", "matters more now that", "returns what it returned before". Describe the
+  resulting state.
+- Sections that restate the summary or another section.
+- Recommended defaults marked "unvalidated", letter variables standing in for them, and any open question that exists
+  only to hold them. A concrete value is implementation policy unless it is normative.
+- Metaphors that introduce their own vocabulary. Use the defined term.
+
+### Shape
+
+- Requirements are constraints any acceptable design must satisfy, not a summary of the chosen design. Four or five
+  items, each one bold word and one sentence.
+- One bullet is one rule, one or two sentences. Long lists become one-liners without bold leads.
+- The design roadmap is a bullet list introduced by "The design has N parts:", with nothing after it.
+- Tables have a one-line caption above them, and rows are phrased in parallel.
+- Rust blocks are complete: the full `pub trait X: Send + Sync { ... }` with default bodies, in the shape of
+  `rust/crates/truapi/src/api/*.rs`. Every field and variant carries a doc comment.
+- A concept shared by several RFCs is defined in one and linked from the others. A dependent RFC states only what it
+  adds.
+- An inline list is a set of examples unless it is declared exhaustive: write "may be" or "such as". An exhaustive set
+  goes in a table or an enum.
+
+### Process
+
+- Read the whole document before editing, then trim section by section in reading order.
+- Earlier text wins. An approved paragraph is normative for everything below it; reconcile downstream text to match.
+- After each edit, search the rest of the document for terms the edit invalidated and fix them in the same pass.
+- After each pass verify: no dangling references or undefined terms.
+- Deleting a whole section is the author's call, not the reviewer's.
+
 ## Before handing it over
 
-Re-read it as a reviewer with ten minutes. Cut what you would skim. Then tell the
-author what you cut and what you assumed.
+Re-read it as a reviewer with ten minutes. Cut what you would skim. Then tell the author what you cut and what you
+assumed.

.prettierrc

@@ -18,6 +18,13 @@
         "tabWidth": 4,
         "printWidth": 100
       }
+    },
+    {
+      "files": ["**/*.md"],
+      "options": {
+        "printWidth": 120,
+        "proseWrap": "always"
+      }
     }
   ]
 }