fix(review): harden + wire remote-host SSH cases end-to-end (PR #145)

- UI: add the missing data-tab="case-remote" tab button; dispatch it through
  submitCaseModal()/switchCaseModalTab() to linkRemoteCase() (was dead code).
- Restore: restoreMuxSessions() now passes remote (muxSession.remote ??
  savedState.remote) into the Session constructor, so remote metadata round-trips
  on restart instead of reattaching from a local cwd / respawning LOCAL / being
  erased from state.json. Recovery tests added.
- Run flows: runClaude()/runShell() route remote cases through /api/quick-start
  (POST /api/sessions stat-validates workingDir locally); run*() skip the
  /api/*/status pre-check and omit inert config/env for remote cases.
- Quick-start: resolve the remote case BEFORE the local CLI availability gates and
  skip isCodex/Gemini/OpenCodeAvailable() when remote; REJECT
  envOverrides/effort/codex/gemini/openCode config for remote (they don't cross
  ssh) instead of silently dropping them.
- Injection: reject $, backtick, $( in remotePath + identityFile at the schema
  layer (they survive shellescape into the bash -c launch double-quote layer).
  Regression tests for $(...) and backtick payloads added.
- Remote socket/name: launch on a DEDICATED -L codeman-remote socket under a
  codeman-ssh-<id> name that fails a remote Codeman's SAFE_MUX_NAME_PATTERN, so a
  remote instance can't adopt the session; scope tmux set-options per-session
  (never -g) so they don't mutate other sessions.
- Kill: best-effort ssh 'tmux -L codeman-remote kill-session' on remote session
  kill (fire-and-forget, never blocks/throws the local kill) so the remote agent
  isn't orphaned forever.
- Probe: wire checkRemoteTmuxAvailable() into POST /api/quick-start (structured
  OPERATION_FAILED) and as courtesy validation in remote-link; add a default
  -o ConnectTimeout=10 to buildSshConnectionArgs (overridable via extraSshOptions).
- Command default: remote claude default is now
  'exec claude --dangerously-skip-permissions' (per-host override stays the escape
  hatch), mirroring local non-interactive semantics.

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

src/web/routes/case-routes.ts

@@ -25,6 +25,7 @@ import { SseEvent } from '../sse-events.js';
 import type { EventPort, ConfigPort } from '../ports/index.js';
 import { dataPath, getDataDir } from '../../config/instance.js';
 import {
+  checkRemoteTmuxAvailable,
   readRemoteCases,
   readRemoteHosts,
   remoteDisplayPath,
@@ -218,6 +219,14 @@ export function registerCaseRoutes(app: FastifyInstance, ctx: EventPort & Config
       return createErrorResponse(ApiErrorCode.ALREADY_EXISTS, 'Case already exists');
     }
 
+    // Courtesy validation: tmux is a hard prerequisite for durable remote sessions.
+    // Verify it up-front so linking surfaces a clear error now instead of a dead pane
+    // at first launch (also confirms the SSH connection actually works).
+    const tmuxCheck = await checkRemoteTmuxAvailable(host);
+    if (!tmuxCheck.ok) {
+      return createErrorResponse(ApiErrorCode.OPERATION_FAILED, tmuxCheck.error || 'remote host is missing tmux');
+    }
+
     await writeRemoteCases(CODEMAN_CONFIG_DIR, [...remoteCases, remoteCase]);
     ctx.broadcast(SseEvent.CaseLinked, { name: remoteCase.name, path: remoteCase.remotePath, type: 'remote' });
     return { success: true, data: { case: remoteCase } };