fix(hub): the members table stops hanging off the side of a phone

`.admin-table` column heads are `white-space: nowrap`, which meets a
translated string: "Username" is one word, "Nom d'utilisateur" is three,
uppercased with letter-spacing on top. The heads alone overflowed a 360px
window by 11px, and on Android an overflowing document takes every sticky
element with it.

11px was only what could be measured: the probe served no members, so the
table measured its headers and nothing else. With one realistic username
in it the same page overflowed by 248px, at 420px-wide windows too. The
cells get `word-break: break-word`, as `.file-name` already had.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

3 files changed, 47 insertions, 2 deletions

diff --git a/CLAUDE.md b/CLAUDE.md
index 5463437..a7ecbca 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -492,6 +492,20 @@ do. Read them before writing anything that touches the same mechanism.
   `autofocus`, and Android's `interactive-widget` default splits the visual
   viewport from the layout one), which was plausible, cost a round trip, and
   was wrong; the screenshot showing no keyboard was already in hand.
+  **It came back on 2026-09-19, one table along, and the fixture hid most of
+  it again.** `.admin-table` overflowed a 360px window by 11px — from its
+  *column heads*, because `white-space: nowrap` met a translated string:
+  "Username" is one word and "Nom d'utilisateur" is three, uppercased with
+  letter-spacing on top. **A label's length is not yours to assume once it goes
+  through `t()`**, and a head that wraps onto two lines is legible where a
+  table the reader cannot reach the right of is not. The 11px was the whole of
+  what could be measured, because the probe served no members at all: an empty
+  table measures its headers and nothing else. With one realistic username in
+  it — no spaces to break at, a string somebody else chose — the same page
+  overflowed by **248px**, and at 420px-wide windows as well as 360. Same
+  lesson as the paragraph above, twice now: the wrapping rule belongs on every
+  cell that carries a name, and the fixture has to carry the names real data
+  has or it measures itself.
 
 - **Derived data that nothing persists is re-derived where somebody is
   watching.** `video_meta`, `photo_meta` and `thumbs` were durable; the audio
diff --git a/packages/meshbay-hub/src/meshbay_hub/static/style.css b/packages/meshbay-hub/src/meshbay_hub/static/style.css
index 81ae895..63f631a 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/style.css
+++ b/packages/meshbay-hub/src/meshbay_hub/static/style.css
@@ -2110,6 +2110,14 @@ button:disabled { opacity: 0.5; cursor: not-allowed; }
   border-collapse: collapse;
   font-size: 0.88em;
 }
+/* A column head is a *translated* string, so its length is not ours to assume:
+   "Username" is one word in English and "Nom d'utilisateur" is three in French,
+   and uppercased with letter-spacing on top. Under `white-space: nowrap` the
+   longer one sets the column's minimum width, and the whole table hangs off the
+   side of a phone — which on Android takes every `position: sticky` element
+   with it, the fault already recorded against the Files table one table along.
+   A head that wraps onto two lines is legible; a table the reader cannot reach
+   the right of is not. */
 .admin-table th {
   text-align: left;
   padding: 8px 10px;
@@ -2119,12 +2127,19 @@ button:disabled { opacity: 0.5; cursor: not-allowed; }
   font-weight: 600;
   text-transform: uppercase;
   letter-spacing: 0.04em;
-  white-space: nowrap;
+  white-space: normal;
 }
+/* And the same rule as `.file-name`, for the same reason: these cells carry
+   names somebody else chose — a username, a group name — and a name with no
+   spaces in it has nowhere to break unless it is told to. The heads alone cost
+   11px of overflow at 360px; with a realistic username in the fixture it was
+   248px, and it reached 420px-wide windows too. */
 .admin-table td {
   padding: 8px 10px;
   border-bottom: 1px solid var(--border);
   vertical-align: middle;
+  word-break: break-word;
+  min-width: 0;
 }
 .admin-table tr:hover { background: var(--bg-raised); }
 .admin-table .admin-empty {
diff --git a/packages/meshbay-hub/tests/harness/sticky_header_probe.py b/packages/meshbay-hub/tests/harness/sticky_header_probe.py
index 6f084d6..7579bf9 100755
--- a/packages/meshbay-hub/tests/harness/sticky_header_probe.py
+++ b/packages/meshbay-hub/tests/harness/sticky_header_probe.py
@@ -401,7 +401,11 @@ const settle = () => new Promise((r) =>
           .slice(0, 6)
           .map((el) => (el.tagName.toLowerCase() + '.' + (el.className || ''))
                          .slice(0, 60) + ' →'
-                       + Math.round(el.getBoundingClientRect().right));
+                       + Math.round(el.getBoundingClientRect().right)
+                       // The text, because the element alone never says which
+                       // cell it was: a column is as wide as its widest
+                       // unwrappable string, and that string is the finding.
+                       + ' ' + JSON.stringify((el.textContent || '').trim().slice(0, 40)));
       })(),
       innerHeight, innerWidth,
       // What the stylesheet was actually handed, so a wrong offset can be told
@@ -487,6 +491,18 @@ class H(http.server.BaseHTTPRequestHandler):
             self._send(render_frame(index).encode(), "text/html; charset=utf-8")
         elif path == "/v1/groups/g1/nodes":
             self._send(b'{"nodes": [{"node_id": "n1"}]}', "application/json")
+        elif path == "/v1/groups/g1/members":
+            # Served at all because an empty table measures only its headers,
+            # and a member's name is a string this project did not choose. One
+            # of them has no spaces to break at, which is what makes a cell set
+            # its column's minimum width — the fault already recorded against
+            # the Files table, one table along.
+            self._send(
+                b'{"members": ['
+                b'{"user_id": "u1", "username": "moi"},'
+                b'{"user_id": "u2", "username":'
+                b' "un_utilisateur_au_nom_deraisonnablement_long_2026"}]}',
+                "application/json")
         else:
             asset = (STATIC / path.lstrip("/")).resolve()
             if not str(asset).startswith(str(STATIC)) or not asset.is_file():