fix(webhook): fetch description from Plane API on status-start

Plane issue.updated (status -> In Progress) ships only changed fields, so the
webhook payload has no description and QG-0 wrongly blocked issues. start_pipeline
now pulls the full description from the Plane issue detail API (reusing the same
GET endpoint + shared token as fetch_issue_sequence_id) when the payload field is
empty/short, before QG-0 runs. Empty API -> honest QG-0 fail (truly empty ticket).

src/plane_sync.py

@@ -155,6 +155,48 @@ def fetch_issue_sequence_id(issue_id: str, project_id: str) -> int | None:
         return None
 
 
+import re as _re
+
+
+def _strip_html(html: str) -> str:
+    """Crude HTML -> text: drop tags and collapse whitespace. Good enough to
+    feed QG-0's length check when Plane only gives us description_html."""
+    if not html:
+        return ""
+    text = _re.sub(r"<[^>]+>", " ", html)
+    return _re.sub(r"\s+", " ", text).strip()
+
+
+def fetch_issue_description(issue_id: str, project_id: str) -> str:
+    """BUG 1: GET the Plane issue by UUID and return its description text.
+
+    Plane's ``issue.updated`` webhook (e.g. a status change) only carries the
+    CHANGED fields, so ``description``/``description_stripped`` are usually
+    absent there. start_pipeline calls this to pull the full description from the
+    issue detail endpoint so QG-0 does not blow up on an empty payload field.
+
+    Reuses the exact GET issue detail endpoint / shared token already used by
+    ``fetch_issue_sequence_id`` (same URL, same PLANE_HEADERS). Prefers
+    ``description_stripped``; falls back to stripping ``description_html``.
+
+    Returns "" on network error, non-2xx, or a missing field - never raises, so
+    a Plane outage degrades to the honest "empty description" QG-0 path instead
+    of crashing the webhook.
+    """
+    url = f"{PLANE_BASE}/workspaces/{WORKSPACE}/projects/{project_id}/issues/{issue_id}/"
+    try:
+        resp = httpx.get(url, headers=PLANE_HEADERS, timeout=10)
+        resp.raise_for_status()
+        body = resp.json()
+        desc = body.get("description_stripped")
+        if desc and desc.strip():
+            return desc
+        return _strip_html(body.get("description_html") or "")
+    except Exception as e:
+        logger.warning(f"fetch_issue_description failed for {issue_id}: {e}")
+        return ""
+
+
 def find_issue_id(work_item_id: str, project_id: str = None) -> str | None:
     """Find Plane issue UUID by work_item_id (e.g. 'ET-002')."""
     project_id = _resolve_project_id(work_item_id, project_id)