dashboard: subscribed nodes' messages as dots

The page reads a subscribed node's message counts from it too, and
draws them as dots on the map, as this node's own.

Auth plan M3 (live data from every reachable node).

3 files changed, 21 insertions, 3 deletions

diff --git a/docs/access.md b/docs/access.md
index 71aebea..e8f9893 100644
--- a/docs/access.md
+++ b/docs/access.md
@@ -106,8 +106,9 @@ curl -H "Authorization: Bearer ct1.…" http://other-node:3000/store
 `GET /auth/whoami` says who a request's user is, how it proved it, and what it may do.
 
 Pages of other origins, the dashboards of other members, may call a node with a token:
-its own links (`/admin/dashboard/links/own`, and its events), `/auth/refresh` and
-`/auth/whoami`, nothing else. A node allows the origins of the dashboards its member
+its own links (`/admin/dashboard/links/own`, and its events) and traffic
+(`/admin/dashboard/traffic/own/events`), `/auth/refresh` and `/auth/whoami`, nothing
+else. A node allows the origins of the dashboards its member
 list names (`--dashboard-url`) and those of `--cors-origins`; without credentials (no
 cookie or password crosses origins: the page sends its token).
 
diff --git a/docs/dashboard.md b/docs/dashboard.md
index e62b67d..45a2248 100644
--- a/docs/dashboard.md
+++ b/docs/dashboard.md
@@ -133,7 +133,10 @@ dots: they would all run at once. A dot is as large as its kind's messages were
 right after their legend makes all dots larger or smaller, and the `speed` slider after
 it makes them run faster or slower (0.1 to 0.9 map units per millisecond, 0.3 at
 first: a link of 200 in about 0.7 s); both are kept in the browser. A picture
-of the traffic, not a record of it; links between other members show none.
+of the traffic, not a record of it. A subscribed node's messages with its peers run
+along its links too, from its own counts (read from it with the page's token, as its
+links are): those with this node are drawn from this node's counts, and between two
+subscribed nodes from what the sender sent. Links between other members show none.
 `messages: on` after the sliders hides them (`messages: off` shows them again; the
 legend and the sliders greyed meanwhile); the choice is kept in the browser.
 
diff --git a/docs/openapi.yaml b/docs/openapi.yaml
index f8fb25d..a5f7dcb 100644
--- a/docs/openapi.yaml
+++ b/docs/openapi.yaml
@@ -1050,6 +1050,20 @@ paths:
         '401':
           $ref: '#/components/responses/Unauthorized'
 
+  /admin/dashboard/traffic/own/events:
+    get:
+      tags: [Admin]
+      summary: This node's traffic with each peer, every 2 s
+      description: Server-sent events, `traffic` with what this node sent to and received from each peer by node ID, by kind (messages and bytes counted since it started, as `/peers` has them), every 2 s; `offline` when the node stops. For a page of another member's dashboard subscribed to this node, to draw its messages on the map (CORS, with a token).
+      responses:
+        '200':
+          description: The events.
+          content:
+            text/event-stream:
+              schema: { type: string }
+        '401':
+          $ref: '#/components/responses/Unauthorized'
+
   /admin/dashboard/refresh:
     post:
       tags: [Admin]