fix(groups): finish Phase 1 — MNP root management, upload targets, eject state

Review of the Phase 1 commit found the RO/RW model sound but three paths
unfinished, each of which broke the flow the phase exists to deliver. Plus
29 test failures it introduced and no coverage for anything it added.

Uploads went to the wrong directory. The node read a `root` field on
file_upload that no client ever sent, so every upload landed in the first
writable root while the Files toolbar offered its button based on the root
being browsed — with two writable roots, uploading from one wrote into the
other. Files now names the root it is showing; Chat names one chosen in the
shell (an operator-configured directory arrives in Phase 2); the node refuses
an unknown name rather than falling back, and refuses read-only and ejected
roots by code.

Shared directories were unreachable on the web. The table read its roots
only from the loopback API, which resolves to "not available" in a browser,
so the section rendered for nobody there — while the Uploads controls it
replaced had worked — and the transport.updateRoot/ejectRoot/plugRoot methods
beside it were dead. MNP is now the path, loopback the fallback for a local
node with no live connection, and adding a root over MNP takes a typed path
since no web page can browse a remote disk.

Ejecting updated nobody's screen. transport.js resolves an admin ack against
the pending request and returns, which is right for every op whose caller
knows the value it chose; the root acks carry state only the node can compute,
so the operator who clicked Eject was the one client that never saw it happen.
And the ejected flag reached roster.db but was never read back, so a restart
undid it and the next scan read an empty mount point as an erased library.

Also: the member-upload endpoint answered 200 and did nothing (removed); the
wizard ignored the first root's RW switch; reload compared roots on name and
path, so editing writable in node.toml did nothing; the table had no path
column, which is the only thing separating two libraries sharing a basename;
apps_enabled normalisation differed between the two sides of a signed subject.

Tests: eject/plug, per-root upload refusal and the node.toml rewrite had no
coverage at all. test_member_upload_policy.py is replaced by
test_root_writable_policy.py — it tested a removed feature — and every
property worth keeping from it moved rather than being dropped.

Docs: draft-v6 structural decision 9 is annotated as superseded (the operator
can no longer have a directory only they may write to — a real capability
removed, flagged rather than hidden), the man page documents the root verb and
the RO/RW fields, and refactor-groups.md §7b records what the plan got wrong.

Suite: 41 failures before, 13 after — all 13 pre-existing on main.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011pvMdvLBG92jyhvD5pD6us

1 files changed, 26 insertions, 8 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
index 1b2661c..dfde172 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/group-page.js
@@ -88,8 +88,10 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
   const [nodeRoots, setNodeRoots] = useState([]);
 
   const [isNodeAdmin, setIsNodeAdmin] = useState(false);
-  // DEPRECATED: memberUpload is now derived from per-root writable flags.
-  // Kept as state only for backward compat with nodes that still send it.
+  // Legacy: the group-wide upload switch a node speaking MNP 1.0 sends on its
+  // handshake ack. Per-root `writable` replaced it, and this is read only when
+  // the roots carry no flags at all — see `attachRoot` below. Defaults to true
+  // so such a node behaves as it always did.
   const [memberUpload, setMemberUpload] = useState(true);
   // Which applications this group has enabled, from the node. Falls back to
   // every registered app when a node predates the setting (or hasn't answered
@@ -539,11 +541,26 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
     }
   }, [groupId, token, descDraft, onGroupUpdated]);
 
-  // Asked in two places — the Files toolbar and the chat composer — so it is
-  // answered once. Per-root writable flags replace the old binary toggle;
-  // falls back to the legacy memberUpload for old nodes.
-  const hasWritableRoot = nodeRoots.some((r) => r.writable);
-  const mayUpload = hasWritableRoot || memberUpload || isNodeAdmin;
+  // Where an attachment goes, answered once for the whole page.
+  //
+  // Files does not use this — it uploads into the root being browsed, which is
+  // the only unambiguous answer once a group can have several writable roots.
+  // Chat has no folder to browse, so it needs one picked for it, and this is
+  // the same rule the node applies when a client names no root at all. It
+  // becomes an operator-chosen directory in phase 2 (refactor-groups.md §1.7).
+  //
+  // `memberUpload` is the fallback for a node still speaking MNP 1.0, whose
+  // roots carry no `writable` at all: there, the single upload root is the one
+  // the node marked, and the ack's computed flag is all we get.
+  const writableRoots = useMemo(
+    () => nodeRoots.filter((r) => r.writable && r.available !== false),
+    [nodeRoots]);
+  const legacyNode = nodeRoots.length > 0
+    && nodeRoots.every((r) => r.writable === undefined);
+  const attachRoot = writableRoots.length ? writableRoots[0].name
+    : (legacyNode && memberUpload
+        ? (nodeRoots.find((r) => r.upload) || nodeRoots[0]).name
+        : '');
 
   // A single dispatcher so any app can open the right modal without owning
   // video/preview state itself — Files' table and Chat's attachments both
@@ -587,7 +604,7 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
     groupId, transportRef, gekRef, status, username,
     entries, availableEntries, nodeDirs, nodeRoots,
     setEntries, setNodeDirs, setNodeRoots, applyIndex,
-    isNodeAdmin, operatorPaired, mayUpload, userId, setError, onPreview,
+    isNodeAdmin, operatorPaired, attachRoot, userId, setError, onPreview,
     onRefreshIndex: refreshIndex, onActivity: touchActivity,
     videoRoot, onVideoRoot: (path) => setVideoRoot(path),
     audioRoot, onAudioRoot: (path) => setAudioRoot(path),
@@ -717,6 +734,7 @@ function GroupPage({ groupId, group, token, username, userId, userPrefs,
             transportRef=${transportRef} gekRef=${gekRef}
             isNodeAdmin=${isNodeAdmin} userId=${userId}
             operatorPaired=${operatorPaired} connected=${status === 'connected'}
+            mnpRoots=${nodeRoots}
             enabledApps=${enabledApps}
             onEnabledApps=${(keys) => setEnabledApps(keys)}
             scanSettings=${scanSettings}