fix(skills): ignore support docs in skill discovery

Support files under references/, templates/, assets/, and scripts/ are progressive-disclosure data loaded through skill_view(..., file_path=...). They should not be treated as standalone skills during discovery or collision checks.

This prevents archived skill packages or support markdown files inside a real skill from shadowing active skills with the same name while still allowing top-level categories named scripts/templates/assets/references.

Tests cover:
- pruning nested SKILL.md files inside skill support directories
- preserving support-named top-level categories
- avoiding skill_view collisions from support markdown
- keeping archived package SKILL.md files accessible only through file_path

agent/skill_utils.py

@@ -43,14 +43,20 @@ EXCLUDED_SKILL_DIRS = frozenset(
     )
 )
 
+# Supporting files live inside a skill package and are loaded explicitly via
+# skill_view(skill, file_path=...). They are not standalone skills and must not
+# be scanned for active SKILL.md/DESCRIPTION.md entries, even if a Curator or
+# archive workflow preserves a complete old skill package under references/.
+SKILL_SUPPORT_DIRS = frozenset(("references", "templates", "assets", "scripts"))
+
 
 def is_excluded_skill_path(path) -> bool:
-    """True if any component of *path* is in EXCLUDED_SKILL_DIRS.
+    """True if *path* should be skipped by active skill scanners.
 
-    Use this on every SKILL.md path produced by ``rglob`` to prune
-    dependency, virtualenv, VCS, and cache directories. Centralising the
-    check here keeps every skill-scanning site in sync with the shared
-    exclusion set.
+    Use this on every ``SKILL.md`` path produced by direct ``rglob`` scans to
+    prune dependency, virtualenv, VCS, cache, and progressive-disclosure
+    support-package paths. Centralising the check here keeps every
+    skill-scanning site in sync with the shared exclusion set.
 
     Accepts a Path or string.
     """
@@ -59,7 +65,36 @@ def is_excluded_skill_path(path) -> bool:
     except AttributeError:
         from pathlib import PurePath
         parts = PurePath(str(path)).parts
-    return any(part in EXCLUDED_SKILL_DIRS for part in parts)
+    return any(part in EXCLUDED_SKILL_DIRS for part in parts) or is_skill_support_path(
+        path
+    )
+
+
+def is_skill_support_path(path) -> bool:
+    """True if *path* is under a support dir of an actual skill root.
+
+    ``references/``, ``templates/``, ``assets/``, and ``scripts/`` are
+    progressive-disclosure support areas when they sit directly inside a skill
+    directory containing ``SKILL.md``. They are not active discovery roots for
+    standalone skills. A preserved package such as
+    ``some-skill/references/old-skill-package/SKILL.md`` is documentation data
+    unless the caller explicitly loads it via ``file_path``.
+
+    Legitimate categories or skill names such as ``skills/scripts/foo`` remain
+    discoverable because their ``scripts`` component is not directly under a
+    directory that contains ``SKILL.md``.
+    """
+    path_obj = path if isinstance(path, Path) else Path(str(path))
+    parts = path_obj.parts
+    # Last component may be a file or candidate skill directory name. Only
+    # components before the leaf can be containing support directories.
+    for idx, part in enumerate(parts[:-1]):
+        if part not in SKILL_SUPPORT_DIRS or idx == 0:
+            continue
+        skill_root = Path(*parts[:idx])
+        if (skill_root / "SKILL.md").exists():
+            return True
+    return False
 
 
 # ── Lazy YAML loader ─────────────────────────────────────────────────────
@@ -661,12 +696,21 @@ def extract_skill_description(frontmatter: Dict[str, Any]) -> str:
 def iter_skill_index_files(skills_dir: Path, filename: str):
     """Walk skills_dir yielding sorted paths matching *filename*.
 
-    Excludes Hermes metadata, VCS, virtualenv/dependency, and cache
-    directories so dependencies cannot register nested skills.
+    Excludes Hermes metadata, VCS, virtualenv/dependency, cache, and skill
+    support directories. Support directories (references/templates/assets/
+    scripts) can contain arbitrary markdown and even archived package
+    ``SKILL.md`` files, but they are progressive-disclosure data loaded through
+    ``skill_view(..., file_path=...)`` rather than active skill roots.
     """
     matches = []
     for root, dirs, files in os.walk(skills_dir, followlinks=True):
-        dirs[:] = [d for d in dirs if d not in EXCLUDED_SKILL_DIRS]
+        has_skill_md = "SKILL.md" in files
+        dirs[:] = [
+            d
+            for d in dirs
+            if d not in EXCLUDED_SKILL_DIRS
+            and not (has_skill_md and d in SKILL_SUPPORT_DIRS)
+        ]
         if filename in files:
             matches.append(Path(root) / filename)
     for path in sorted(matches, key=lambda p: str(p.relative_to(skills_dir))):