feat: remote parity with ssh + codex resume on the same host

[constansino]

Problem / workflow

A key remote workflow for me is:

• Codex CLI is installed and used on a Mac
• I often work from Windows
• today I can ssh into the Mac, run codex resume, and access the Mac's existing Codex sessions with the same auth/config/environment as if I were sitting at the Mac

T3 Code's remote web mode is very close to being a great replacement for this workflow, but it currently cannot fully replace ssh -> codex resume for an existing Codex installation on the same host.

What is missing

To make this work end-to-end, T3 Code needs all of the following together:

1. Actually honor the configured Codex binary / CODEX_HOME for new sessions and health checks
   • otherwise T3 may not be pointing at the same Codex install / auth / session store as the CLI
2. Discover and/or import existing Codex sessions already available to that configured Codex install
   • either by thread id, from a recent-session list, or from the underlying Codex session store used by codex resume
3. Resume/read imported sessions inside T3 Code
   • once imported, those sessions should be openable from T3 and resumable/readable remotely from another device
4. Refresh/re-scan without duplicates
   • manual refresh is enough for an MVP; real-time sync is not required

Important scope clarification

This is not asking for one T3 instance to directly manage arbitrary LAN hosts.

The request is narrower and simpler:

If T3 Code is running on the same machine as Codex CLI, and I access T3 remotely from another device, it should be able to act like a real GUI for that host's existing Codex sessions.

In other words, I want remote parity with:

ssh into host -> codex resume

not a multi-host orchestration system.

Why this matters

This would make T3 Code much more useful as a remote UI for an existing Codex workstation.

Right now T3 feels strongest for sessions created inside T3 itself. For users who already have significant Codex CLI history on a machine, the missing piece is being able to surface and continue those existing sessions from T3 when accessing that machine remotely.

Related issues

• Feat: Load existing Codex threads available via codex resume #330 Feat: Load existing Codex threads available via codex resume
• request: import or recreate sessions from Codex #207 request: import or recreate sessions from Codex
• Settings UI 'Codex binary path' has no effect #486 Settings UI 'Codex binary path' has no effect
• feat: support quick switching between multiple Codex accounts / auth profiles #229 feat: support quick switching between multiple Codex accounts / auth profiles

I think this issue is best understood as the remote same-host workflow that depends on / ties together the first three items above. #229 is related for multi-profile users, but not required for the core workflow.

Suggested MVP

• Make Codex binary path and Codex home path actually affect session startup / checks
• Add an Import existing Codex session flow:
  • import by thread id and/or
  • select from recent sessions visible to the configured Codex install
• Persist an imported thread mapping using the provider thread id / resume cursor
• Allow manual refresh / re-scan to discover new sessions without duplicating already imported ones
• Clearly label imported sessions as imported/external

Acceptance criteria

• The configured Codex binary and CODEX_HOME actually affect which Codex install/session store T3 uses
• T3 can scan or import sessions that already exist for that Codex install
• Imported sessions can be opened, resumed, and read from T3
• Accessing T3 remotely from another device works for those imported sessions just like it does for T3-native sessions
• Refresh/re-scan deduplicates by provider thread id (or equivalent durable Codex thread identity)
• Real-time sync is optional; manual refresh is sufficient for the first version

[rodalpho]

I similarly develop in a remote Linux vm accessed via ssh for safety. I run in YOLO mode and that is obviously not a good idea on my desktop. This works great in vscode and I'd love this functionality in t3 code.