add mini-context-graph skill (#1580)

* add mini-context-graph skill

* remove pycache files

* filename case update to SKILL.md

* update readme

skills/mini-context-graph/scripts/tools/retrieval_engine.py

@@ -0,0 +1,58 @@
+"""
+retrieval_engine.py — BFS-based graph traversal for context retrieval.
+
+Input: seed node_ids + depth
+Output: list of node_ids within traversal depth filtered by min_confidence
+"""
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from collections import deque
+
+# Allow imports from parent package
+sys.path.insert(0, str(Path(__file__).parent.parent))
+
+from tools import graph_store
+import config
+
+
+def retrieve(
+    seed_node_ids: list[str],
+    depth: int = config.MAX_GRAPH_DEPTH,
+    min_confidence: float = config.MIN_CONFIDENCE,
+    max_nodes: int = config.MAX_NODES,
+) -> list[str]:
+    """
+    BFS from seed nodes up to `depth` hops.
+
+    Returns a list of node_ids (including seeds) within the traversal,
+    filtered by min_confidence on edges and capped at max_nodes.
+    """
+    visited: set[str] = set()
+    # Queue items: (node_id, current_depth)
+    queue: deque[tuple[str, int]] = deque()
+
+    for seed in seed_node_ids:
+        if seed not in visited:
+            visited.add(seed)
+            queue.append((seed, 0))
+
+    while queue:
+        if len(visited) >= max_nodes:
+            break
+
+        node_id, current_depth = queue.popleft()
+
+        if current_depth >= depth:
+            continue
+
+        neighbors = graph_store.get_neighbors(node_id, min_confidence=min_confidence)
+        for neighbor in neighbors:
+            if neighbor not in visited:
+                visited.add(neighbor)
+                queue.append((neighbor, current_depth + 1))
+                if len(visited) >= max_nodes:
+                    break
+
+    return list(visited)