feat: let the operator purge a group's chat (MNP 6.1)

Signed chat_purge from the Chat settings deletes every stored message;
epoch keys and attachments stay. The ack is broadcast so open chat
panels empty.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/ops/chat.py b/packages/meshbay-node/src/meshbay_node/ops/chat.py
index 539284b..9fc7b94 100644
--- a/packages/meshbay-node/src/meshbay_node/ops/chat.py
+++ b/packages/meshbay-node/src/meshbay_node/ops/chat.py
@@ -252,3 +252,22 @@ async def prune_chat(state: dict, group_id: str, max_age_days: int) -> dict:
              group_id[:8], removed)
     return {"group_id": group_id, "removed": removed,
             "max_age_days": max_age_days}
+
+
+async def purge_chat(state: dict, group_id: str) -> dict:
+    """
+    Delete every stored message of the group. Epoch keys are kept, as in
+    `prune_chat`, and attachments too: they are files in a shared folder.
+
+    The replay index goes with the rows, which is harmless: the node takes a
+    sealed message only from the device that signed it, so the one party able
+    to send a purged message again is its author.
+    """
+    ctx = _group_ctx(state, group_id)
+    store = ctx.get("chat_store")
+    if store is None:
+        raise OpError("This group has no chat store", status=404)
+    removed = await store.delete_all()
+    log.info("Chat purged for group %s: %d message(s) removed",
+             group_id[:8], removed)
+    return {"group_id": group_id, "removed": removed}