skills: drop pyyaml dep, hand-roll description parser

The previous fix added `pip install pyyaml` to the validate workflow,
but the databricks-protected-runner can't reach pypi.org (SSL errors
on every retry). Restoring a stdlib-only description parser sidesteps
the network requirement entirely.

The hand-rolled parser is the same shape as the pre-db9b2e5 version:
handles plain, quoted, and block-scalar (>- / |-) values. db9b2e5
moved to yaml.safe_load to also unescape inner \" sequences, but no
current SKILL.md description uses that escape, so the regression
risk is nil. Re-introducing pyyaml is a one-line change if a future
description ever needs it.

Manifest regenerated; no content drift, only updated_at moved.

Co-authored-by: Isaac

Author: jamesbroadhead

.github/workflows/validate-manifest.yml

@@ -25,8 +25,5 @@ jobs:
         with:
           python-version: '3.11'
 
-      - name: Install Python deps
-        run: pip install pyyaml
-
       - name: Validate manifest is up to date
         run: python3 scripts/skills.py validate

manifest.json

@@ -1,6 +1,6 @@
 {
   "version": "2",
-  "updated_at": "2026-05-18T21:44:44Z",
+  "updated_at": "2026-05-19T14:54:40Z",
   "skills": {
     "databricks-apps": {
       "version": "0.1.1",

scripts/skills.py

@@ -9,8 +9,6 @@
 from datetime import datetime, timezone
 from pathlib import Path
 
-import yaml
-
 
 SHARED_ASSETS = [
     "assets/databricks.svg",
@@ -194,8 +192,17 @@ def check_assets_synced(repo_root: Path) -> list[str]:
 # Manifest generation
 # ---------------------------------------------------------------------------
 
+_BLOCK_SCALAR_INDICATORS = {"|", "|-", "|+", ">", ">-", ">+"}
+
+
 def extract_description_from_skill(skill_path: Path) -> str:
-    """Best-effort extraction of `description:` from SKILL.md frontmatter."""
+    """Best-effort extraction of `description:` from SKILL.md frontmatter.
+
+    Handles plain (`description: foo`), quoted (`description: "foo"`), and
+    block-scalar (`description: >-` followed by indented lines) values.
+    Stdlib-only to keep the validate workflow on the protected runner
+    self-contained — that runner can't reach pypi.org.
+    """
     skill_md = skill_path / "SKILL.md"
     if not skill_md.exists():
         return ""
@@ -205,9 +212,24 @@ def extract_description_from_skill(skill_path: Path) -> str:
     end_idx = content.find("---", 3)
     if end_idx == -1:
         return ""
-    parsed = yaml.safe_load(content[3:end_idx]) or {}
-    description = parsed.get("description", "")
-    return description.strip() if isinstance(description, str) else ""
+    lines = content[3:end_idx].splitlines()
+    for i, line in enumerate(lines):
+        m = re.match(r'^description:\s*(.*?)\s*$', line)
+        if not m:
+            continue
+        value = m.group(1)
+        if value in _BLOCK_SCALAR_INDICATORS:
+            collected = []
+            for cont in lines[i + 1:]:
+                if cont and not cont[0].isspace():
+                    break
+                stripped = cont.strip()
+                if stripped:
+                    collected.append(stripped)
+            joiner = " " if value.startswith(">") else "\n"
+            return joiner.join(collected)
+        return value.strip().strip('"').strip("'")
+    return ""
 
 
 # Markers that separate the "what this skill does" lead-in from the