docs: extend graph info

src/content/user_guide/dashboard/index.md

@@ -37,6 +37,7 @@ Once you've signed in, your session is cached locally so future launches of `fen
 | **Overview** (`/`) | All projects with logged sessions, at a glance |
 | **Project** (`/project/<name>`) | All sessions for a single project |
 | **Session** (`/session/<project>/<id>`) | Full detail for one session - logs, metadata, status |
+| **Metric Detail** (`/session/<project>/<id>/metric/<name>`) | Full-size chart for a single metric, reached via "View details" on the session's Graphs tab |
 | **Templates** (`/templates`) | Templates you've pulled locally, with the option to launch them - see [Managing Templates](templates.md) |
 
 For details on filtering, renaming, and archiving sessions, see [Managing Sessions](sessions.md).

src/content/user_guide/dashboard/sessions.md

@@ -119,4 +119,12 @@
     - **Validation Loss**
     - **Accuracy**
 
-    Sessions without metric data simply display an empty state in the Graphs tab.
+    Sessions without metric data simply display an empty state in the Graphs tab.
+
+    Each chart shows axis labels for the minimum and maximum values, and hovering over the line displays the exact step/value at that point.
+
+    ## Metric detail view
+
+    Click **View details** on any chart card to open a full-size view of that metric at `/session/<project>/<id>/metric/<name>`. The detail view shows only that metric's data and animates the line in when the page loads.
+
+    If the session or metric doesn't exist, or the session has no data for that metric, the page returns a 404.