fix(multiuser): close cross-user web-layer scoping holes found in review

The opt-in multi-user feature's only enforcement is web-layer scoping
(all sessions share one OS account). An adversarial review found 8 critical
+ 7 high cross-user holes that defeated it, plus mediums; all fixed here.
Single-user (flag-off) behavior stays byte-identical apart from documented
consistency deltas.

Ownership / confinement:
- DELETE /api/sessions (bulk) + /:id now owner-scope / findSessionOrFail
- quick-start, cron (create+fire), scheduled runs confine workingDir to the
  owner's space; case link/docker-link/docker-import confine the host path
- resolveCasePath no longer resolves linked cases for non-admins; foreign
  remote/docker cases are skipped (fall through to the caller's own local case)
- history, subagents/workflows, mux-sessions, orchestrator, cron run-history,
  away-digest, and remote/docker host reads are owner- or admin-scoped

Permission policy (section 6.3):
- non-granted users are downgraded at every spawn site incl. legacy
  /api/scheduled, PlanOrchestrator one-shots, remote launch, and the cron-fire
  gemini/codex bypass switches; resolveClaudeModeForUsername now fails closed

Auth / store:
- verify-first login throttle (a correct password is never locked out),
  /ws terminal subject to the change-password lockbox, cookie fast-path
  re-validates identity live, role/grant changes revoke sessions, admin delete
  runs the last-admin guard before any teardown
- users.json: distinguish missing (ENOENT) from corrupt/unreadable so a bad
  read can't overwrite all accounts; unique per-process temp write path

Event streams:
- debounced session:updated + batched task:updated, clipboard, and push
  notifications route by owner (fail closed); getLightState hides machine-wide
  globalStats from non-admins

Tests: two suites updated to assert the fixed (secure) behavior. tsc, eslint,
and test:ci all green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/tmux-manager.ts

@@ -779,9 +779,22 @@ export function buildRemoteLaunchCommand(options: {
   mode: SessionMode;
   remote: SessionRemote;
   sessionId: string;
+  claudeMode?: ClaudeMode;
+  allowedTools?: string;
 }): string {
-  const { mode, remote, sessionId } = options;
-  const modeCommand = remote.commands?.[mode] || defaultRemoteCommandForMode(mode);
+  const { mode, remote, sessionId, claudeMode, allowedTools } = options;
+  // §6.3: honor the session's EFFECTIVE claude permission mode on remote instead of
+  // hardcoding --dangerously-skip-permissions, so a non-granted multi-user user's
+  // downgraded 'auto' actually reaches the remote agent (the default command otherwise
+  // ignored claudeMode). A per-host `commands.claude` override stays authoritative
+  // (admin's explicit choice). For the DEFAULT single-user config (skip), the emitted
+  // command is byte-identical to before. Non-claude modes are unchanged.
+  const override = remote.commands?.[mode];
+  const modeCommand = override
+    ? override
+    : mode === 'claude'
+      ? `exec claude${buildClaudePermissionFlags(claudeMode, allowedTools)}`
+      : defaultRemoteCommandForMode(mode);
   const remoteName = remoteTmuxSessionName(sessionId);
 
   // Innermost: the command tmux runs in the new pane. Run via `/bin/sh -c` by
@@ -1559,7 +1572,7 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
       const fullCmd = docker
         ? buildDockerLaunchCommand(resolveDockerLaunchOptions(mode, docker, sessionId, resumeSessionId))
         : remote
-          ? buildRemoteLaunchCommand({ mode, remote, sessionId })
+          ? buildRemoteLaunchCommand({ mode, remote, sessionId, claudeMode, allowedTools })
           : localFullCmd;
 
       // Create tmux session in three steps to handle cold-start (no server running)
@@ -1814,7 +1827,7 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
     const fullCmd = docker
       ? buildDockerLaunchCommand(resolveDockerLaunchOptions(mode, docker, sessionId, resumeSessionId))
       : remote
-        ? buildRemoteLaunchCommand({ mode, remote, sessionId })
+        ? buildRemoteLaunchCommand({ mode, remote, sessionId, claudeMode, allowedTools })
         : localFullCmd;
 
     try {