BEFORE — real T3 server / CLI reproduction
Commit: f03db4fbef59c42113e37c32897bf4d25d31cb2b
Environment: Linux x86_64; Node 26.12.1; OpenCode CLI 2.2.7 (@opencode/cli).
Fresh isolated T3 database; isolated XDG directories; synthetic project only.
T3CODE_DEV_SEED=0; OpenCode enabled; other providers disabled.
OpenCode Go configured with a dummy credential; no successful model reply is expected.
CLI surface: viewport and theme do not apply.
Target model identifier redacted for publication.

Saved defaultModelSelection:
{
  "instanceId": "opencode",
  "model": "opencode-go/<target-model>",
  "options": [
    {
      "id": "variant",
      "value": "medium"
    }
  ]
}

$ t3 thread start <project> "Say hi again" --wait --json
{
  "threadId": "<synthetic-thread>",
  "runId": "<synthetic-run>",
  "status": "failed",
  "reply": null,
  "error": "Variant unavailable for opencode-go/<target-model>: medium"
}
Exit status: 1

$ t3 thread start <project> "Say hi again" --provider opencode --model <target-model> --wait --json
{
  "threadId": "<synthetic-thread>",
  "runId": "<synthetic-run>",
  "status": "failed",
  "reply": null,
  "error": "Invalid credential"
}
Exit status: 1

Live app RPC: server.refreshProviders({instanceId:"opencode", cwd:<project>, fresh:true, refreshModels:true})
{
  "installed": true,
  "version": "2.2.7",
  "status": "ready",
  "targetModel": {
    "slug": "opencode-go/<target-model>",
    "subProvider": "OpenCode Go",
    "isCustom": false,
    "capabilities": {
      "optionDescriptors": [
        {
          "id": "variant",
          "label": "Reasoning",
          "type": "select",
          "options": [
            {
              "id": "low",
              "label": "Low"
            },
            {
              "id": "high",
              "label": "High"
            },
            {
              "id": "max",
              "label": "Max"
            }
          ]
        }
      ]
    }
  }
}

Persisted thread model selections, read-only after server shutdown:
[
  {
    "instanceId": "opencode",
    "model": "opencode-go/<target-model>",
    "options": [
      {
        "id": "variant",
        "value": "medium"
      }
    ]
  },
  {
    "instanceId": "opencode",
    "model": "opencode-go/<target-model>"
  }
]

OpenCode runtime log causes (first line, stack traces omitted):
SessionRunnerModel.VariantUnavailableError: Variant unavailable for opencode-go/<target-model>: medium
AI.Error: Invalid credential

AI-assisted; verified with the tests and tools listed above.
Evidence is runtime output; no tests were used as proof.