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, 37 insertions, 16 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/roster.py b/packages/meshbay-node/src/meshbay_node/roster.py
index e2f749f..5f38acd 100644
--- a/packages/meshbay-node/src/meshbay_node/roster.py
+++ b/packages/meshbay-node/src/meshbay_node/roster.py
@@ -31,6 +31,8 @@ from pathlib import Path
 
 import aiosqlite
 
+from meshbay_common.paths import fold
+
 log = logging.getLogger(__name__)
 
 # Crockford base32 without I, L, O and U: no character pair a human can confuse
@@ -543,10 +545,40 @@ class Roster:
 
     # ── Group settings ──────────────────────────────────────────────────────
 
-    # Whether members who are not the operator may upload. Default is yes: a
-    # group that nobody may add to is the unusual case, and an existing node
-    # must not change behaviour because a table was added under it.
-    SETTING_MEMBER_UPLOAD = "member_upload"
+    # Whether a root is ejected. Runtime state, one key per root, keyed by the
+    # *folded* name so it agrees with the case-insensitive comparison the rest
+    # of the root code makes. It lives here rather than in node.toml because it
+    # is not configuration — an operator's hand-written config file should not
+    # be rewritten because a USB drive was unplugged — and it has to survive a
+    # restart, or the rescan that follows reads an empty mount point as an
+    # erased library, which is the whole thing eject exists to prevent.
+    SETTING_ROOT_EJECTED_PREFIX = "root_ejected:"
+
+    @classmethod
+    def root_ejected_key(cls, root_name: str) -> str:
+        return cls.SETTING_ROOT_EJECTED_PREFIX + fold(root_name)
+
+    async def set_root_ejected(self, group_id: str, root_name: str,
+                               ejected: bool, set_by: str = "") -> None:
+        await self.set_setting(group_id, self.root_ejected_key(root_name),
+                               "1" if ejected else "0", set_by)
+
+    async def ejected_roots(self, group_id: str) -> set[str]:
+        """
+        The folded names of this group's ejected roots.
+
+        Matched in Python rather than with `LIKE 'root_ejected:%'`: `_` is a
+        single-character wildcard there, so that pattern also matches keys this
+        does not own. A group has a handful of settings rows, so reading them
+        all costs nothing and the prefix test is then exact.
+        """
+        prefix = self.SETTING_ROOT_EJECTED_PREFIX
+        async with self._db.execute(
+                "SELECT key, value FROM group_settings WHERE group_id = ?",
+                (group_id,)) as cur:
+            rows = await cur.fetchall()
+        return {r["key"][len(prefix):] for r in rows
+                if r["key"].startswith(prefix) and r["value"] == "1"}
 
     async def get_setting(self, group_id: str, key: str,
                           default: str | None = None) -> str | None:
@@ -567,17 +599,6 @@ class Roster:
             (group_id, key, value, set_by, _now()))
         await self._db.commit()
 
-    async def member_upload_allowed(self, group_id: str) -> bool:
-        """Whether an ordinary member may upload to this group."""
-        value = await self.get_setting(group_id, self.SETTING_MEMBER_UPLOAD, "1")
-        return value != "0"
-
-    async def set_member_upload(self, group_id: str, allowed: bool,
-                                set_by: str = "") -> bool:
-        await self.set_setting(group_id, self.SETTING_MEMBER_UPLOAD,
-                               "1" if allowed else "0", set_by)
-        return allowed
-
     # Which group "applications" (Chat, Files, and whatever registers later in
     # apps.js) are shown to members. Unset means every app that exists — an
     # existing group's tabs must not disappear because a node was upgraded.
@@ -609,7 +630,7 @@ class Roster:
     # user_id)` authorizing the operator node-wide (desktop-client-v1.md
     # §6.3). Unset means "the shipped default token, TMDB's own default
     # language" — the same "absent means the old behaviour" discipline
-    # member_upload/enabled_apps already follow.
+    # enabled_apps already follows.
     #
     # Whether TMDB is used *at all*, though, is per-group (moved off the
     # node-wide sentinel below, 2026-08-24): an operator running a real media