populate member from the authenticated socket

The last mechanical link: chat socket -> resolveMemberRun(userId) ->
ClaudeSpawnStreamingParams.member -> claude-manager's branch ->
spawnClaudeAsMember -> sudo setpriv. The path from a request to a privilege drop
is now complete.

Resolved from the authenticated socket, never from the client message — the same
rule server.tsx applies to the pty sidecar, where it deletes any client-supplied
osUser/home from the query string before setting its own.

resolveMemberRun returns undefined rather than throwing when a home cannot be
resolved, because undefined means "the owner" downstream: an account with no
Linux user has nothing to confine a turn to, and falling back to the owner is
the one wrong answer that must not happen by accident. A separate function with
that reasoning attached rather than an inline ternary.

Still inert. Both gates refuse non-owners before this line is reached, so the
only path that reaches it today returns undefined via isOwner.

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

src/servers/api/chat/websocket.ts

@@ -17,7 +17,8 @@ import { ensureGeneralChatSessionsCwd } from './claude-sessions';
 import * as sidecar from '@@/sidecar-registry';
 import { join } from 'path';
 import { getOwnerHomeDir, getEmailAccountsDir } from '../../../servers/data-path';
-import { getUserSettings, getEmailAccounts, getChatEventsSince, appendChatEvent } from 'officerdb';
+import { getUserSettings, getEmailAccounts, getChatEventsSince, appendChatEvent, getUserById } from 'officerdb';
+import { resolveHomeDir } from '@@/user-home';
 import { mkdirSync } from 'node:fs';
 import { logger } from './logger';
 
@@ -28,6 +29,21 @@ const DEFAULT_MODEL = 'claude-code';
 // (opencode/anthropic/openai/… — all `providerID/modelID` ids) runs through the OpenCode server.
 const isClaudeModel = (model: string): boolean => model.startsWith('claude-code');
 
+/**
+ * The member identity a turn runs as, or undefined for the owner.
+ *
+ * Returns undefined rather than throwing when the home cannot be resolved: an account with no Linux user has
+ * nothing to confine a turn to, and the caller must not silently fall back to running it as the owner. Since
+ * both gates still refuse non-owners, the only path that reaches this today returns undefined via `isOwner`.
+ */
+async function resolveMemberRun(userId: number): Promise<{ osUser: string; home: string } | undefined> {
+  const resolved = await resolveHomeDir(userId);
+  if (!resolved.ok || resolved.isOwner) return undefined;
+  const row = await getUserById(userId);
+  if (!row?.osUser) return undefined;
+  return { osUser: row.osUser, home: resolved.home };
+}
+
 async function getUserDefaultModel(userId: number): Promise<string | null> {
   try {
     const settings = await getUserSettings(userId);
@@ -359,6 +375,15 @@ async function handleClaudeCodeChat(
         sessionKey: sessionId,
         cwd,
         model,
+        // Whose Linux account this turn runs as. Resolved here from the authenticated socket, never from the
+        // client message — the same rule `server.tsx` applies to the pty sidecar, where it deletes any
+        // client-supplied `osUser`/`home` from the query string before setting its own.
+        //
+        // Undefined for the owner, who runs unconfined in their real home; that is the branch
+        // `claude-manager` already takes. Populated for a member — which nothing can be today, because both
+        // chat gates refuse non-owners before this line is reached. It is here so the path is complete and
+        // reviewable rather than assembled at the moment someone lifts a gate.
+        member: await resolveMemberRun(userId),
         resumeSessionId: msg.resumeSessionId,
         onMessage,
       });