fix: enforce Codex 1024-char description limit + auto-heal stale installs (v0.11.9.0) (#391)

* fix: enforce 1024-char Codex description limit + auto-heal stale installs

Build-time guard in gen-skill-docs.ts throws if any Codex description
exceeds 1024 chars. Setup always regenerates .agents/ to prevent stale
files. One-time migration in gstack-update-check deletes oversized
SKILL.md files so they get regenerated on next setup/upgrade.

* chore: bump version and changelog (v0.11.9.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

bin/gstack-update-check

@@ -31,6 +31,24 @@ if [ "$_UC" = "false" ]; then
   exit 0
 fi
 
+# ─── Migration: fix stale Codex descriptions (one-time) ───────
+# Existing installs may have .agents/skills/gstack/SKILL.md with oversized
+# descriptions (>1024 chars) that Codex rejects. We can't regenerate from
+# the runtime root (no bun/scripts), so delete oversized files — the next
+# ./setup or /gstack-upgrade will regenerate them properly.
+# Marker file ensures this runs at most once per install.
+if [ ! -f "$STATE_DIR/.codex-desc-healed" ]; then
+  for _AGENTS_SKILL in "$GSTACK_DIR"/.agents/skills/*/SKILL.md; do
+    [ -f "$_AGENTS_SKILL" ] || continue
+    _DESC=$(awk '/^---$/{n++;next}n==1&&/^description:/{d=1;sub(/^description:\s*/,"");if(length>0)print;next}d&&/^  /{sub(/^  /,"");print;next}d{d=0}' "$_AGENTS_SKILL" | wc -c | tr -d ' ')
+    if [ "${_DESC:-0}" -gt 1024 ]; then
+      rm -f "$_AGENTS_SKILL"
+    fi
+  done
+  mkdir -p "$STATE_DIR"
+  touch "$STATE_DIR/.codex-desc-healed"
+fi
+
 # ─── Snooze helper ──────────────────────────────────────────
 # check_snooze <remote_version>
 #   Returns 0 if snoozed (should stay quiet), 1 if not snoozed (should output).