Enhance issue management tools: add relations and watchers functionality, update README

app/entities/relations.py

@@ -0,0 +1,84 @@
+import json
+from ..mcp import mcp
+from ..client import _get, _post, _delete
+
+
+@mcp.tool()
+def get_issue_relations(issue_id: int) -> str:
+    """
+    Get all relations for a Redmine issue.
+    Returns relation IDs needed for remove_issue_relation.
+    """
+    data = _get(f"/issues/{issue_id}/relations.json")
+    return json.dumps(data.get("relations", []), ensure_ascii=False, indent=2)
+
+
+@mcp.tool()
+def add_issue_relation(
+    issue_id: int,
+    related_issue_id: int,
+    relation_type: str = "relates",
+    delay: int = 0,
+) -> str:
+    """
+    Add a relation between two Redmine issues.
+
+    Args:
+        issue_id:         Source issue ID
+        related_issue_id: Target issue ID
+        relation_type:    Type of relation:
+                          - relates       — generic relation
+                          - duplicates    — this issue duplicates the target
+                          - duplicated    — this issue is duplicated by the target
+                          - blocks        — this issue blocks the target
+                          - blocked       — this issue is blocked by the target
+                          - precedes      — this issue must precede the target
+                          - follows       — this issue must follow the target
+                          - copied_to     — this issue was copied to the target
+                          - copied_from   — this issue was copied from the target
+        delay:            Delay in days (used with precedes/follows)
+    """
+    body: dict = {"issue_to_id": related_issue_id, "relation_type": relation_type}
+    if delay:
+        body["delay"] = delay
+    data = _post(f"/issues/{issue_id}/relations.json", {"relation": body})
+    return json.dumps(data.get("relation", {}), ensure_ascii=False, indent=2)
+
+
+@mcp.tool()
+def remove_issue_relation(relation_id: int) -> str:
+    """
+    Remove a relation between issues by relation ID.
+    Use get_issue_relations to find the relation ID.
+
+    Args:
+        relation_id: Relation ID (from get_issue_relations)
+    """
+    _delete(f"/relations/{relation_id}.json")
+    return f"Relation #{relation_id} removed."
+
+
+@mcp.tool()
+def add_watcher(issue_id: int, user_id: int) -> str:
+    """
+    Add a watcher to a Redmine issue.
+
+    Args:
+        issue_id: Redmine issue ID
+        user_id:  User ID to add as watcher (use get_project_members to find IDs)
+    """
+    _post(f"/issues/{issue_id}/watchers.json", {"user_id": user_id})
+    return f"User #{user_id} added as watcher to issue #{issue_id}."
+
+
+@mcp.tool()
+def remove_watcher(issue_id: int, user_id: int) -> str:
+    """
+    Remove a watcher from a Redmine issue.
+
+    Args:
+        issue_id: Redmine issue ID
+        user_id:  User ID to remove from watchers
+    """
+    _delete(f"/issues/{issue_id}/watchers/{user_id}.json")
+    return f"User #{user_id} removed from watchers of issue #{issue_id}."