fix(spacecraft-document-format): trim description under the 1024-char SKILL limit; document the rule

The Texinfo-first rewrite pushed the frontmatter description to 1058 chars,
which the skill loader rejects (hard limit 1024). Trimmed to 966 (58-char
margin) with every load-bearing fact intact, and rebuilt both bundles.

Also document the limit so it doesn't recur:
- new committed AGENTS.md — tool-agnostic digest of the rules that bite,
  led by the description ≤1024 rule, pointing to CLAUDE.md for the full workflow.
- (CLAUDE.md, gitignored/local, also gains the rule + a folded-aware check.)

A repo-wide sweep confirms all 19 skills are now under the limit; gnu-coding-standards
(1003) and spacecraft-guile-guidelines (1001) sit close, so the rule flags them
for any future description edit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: UnbreakableMJ

AGENTS.md

@@ -0,0 +1,27 @@
+# AGENTS.md — Construct skill catalogue
+
+Tool-agnostic guidance for any agent (Claude, Codex, Gemini, Grok, …) editing
+skills in this repo. The full, detailed workflow lives in `CLAUDE.md` (local,
+gitignored); this file is the committed digest of the rules that bite.
+
+## Hard rules
+
+- **`SKILL.md` frontmatter `description` ≤ 1024 characters.** The loader rejects
+  any skill over the limit (`field 'description' in SKILL.md must be at most
+  1024 characters`). Folded `description: >` blocks render by joining lines with
+  spaces (blank lines → newlines, plus a trailing newline); that *rendered*
+  length is what counts, not the raw line count. Keep a margin — target ≤ 1000.
+  Some descriptions already run close, so re-check after any description edit.
+- **Rebuild BOTH bundles after any skill-dir edit**, in the same commit:
+  `<name>.zip` (`zip -qr`, keeps dir entries) and `<name>.skill` (`zip -qrD`,
+  drops them). A bundle that lags its `SKILL.md`/`references/` ships broken
+  content to every consumer.
+- **Stage explicitly by name — never `git add -A` / `git add .`.** Other root
+  `.skill` files carry unrelated uncommitted changes that must not be swept in.
+- **Commit in UTC, signed** (signing is global, no flag needed); assistant
+  commits add a `Co-Authored-By: Claude …` trailer.
+- **Keep the README §2 catalogue row in sync** when adding, removing, or
+  re-scoping a skill.
+
+See `CLAUDE.md` for the bundling commands, the drift sweep, the push procedure,
+and the Home Manager local fan-out.

spacecraft-document-format.skill

@@ -1,20 +1,18 @@
 ---
 name: spacecraft-document-format
 description: >
-  Authoring rules for Spacecraft Software documents. Texinfo is the canonical
-  format for prose documents (manuals, references, guides, reports, books) — a
-  single `.texi` source compiles to plain text/Info, HTML, and PDF, and converts
-  to GFM Markdown, so structure and brand are defined once and every output
-  stays in sync (Standard §8). ODF (.odt) is the secondary prose format and the
-  primary format for spreadsheets (.ods) and presentations (.odp), which Texinfo
-  cannot represent. Microsoft Office (.docx/.xlsx/.pptx) is the proprietary
-  last-resort, used only when a consumer explicitly requires an MS-native file.
-  Every binary ODF/MS-Office deliverable MUST ship a same-named GFM Markdown
-  (.md) companion; Texinfo is exempt since the .texi is already plain text. PDF
-  is always an export (texi2pdf, or LibreOffice headless), never hand-authored.
-  Documents default to the CC-BY-SA-4.0 document license (GFDL-1.3-or-later
-  permitted for Texinfo manuals). All rich-text outputs apply Void Navy
-  (#000027) background and the Standard §11 palette + §12 typography.
+  Authoring rules for Spacecraft Software documents. Texinfo is canonical for prose
+  (manuals, references, guides, reports, books): one .texi source compiles to plain
+  text/Info, HTML, and PDF and converts to GFM Markdown, so structure and brand are
+  defined once (Standard §8). ODF (.odt) is the secondary prose format and the primary
+  format for spreadsheets (.ods) and presentations (.odp), which Texinfo cannot represent.
+  Microsoft Office (.docx/.xlsx/.pptx) is the proprietary last resort, only when a consumer
+  requires an MS-native file. Every binary ODF/MS-Office deliverable MUST ship a same-named
+  GFM Markdown (.md) companion; Texinfo is exempt (the .texi is already plain text). PDF is
+  always an export (texi2pdf, or LibreOffice headless), never hand-authored. Documents
+  default to the CC-BY-SA-4.0 document license (GFDL-1.3-or-later permitted for Texinfo
+  manuals). All rich-text outputs apply Void Navy (#000027) and the Standard §11 palette +
+  §12 typography.
 license: GPL-3.0-or-later
 maintainer: Mohamed Hammad <Mohamed.Hammad@SpacecraftSoftware.org>
 website: https://Construct.SpacecraftSoftware.org/