Bug: Workspace-authenticated Codex ignores configured default `model` and `service_tier`

What version of Codex CLI is running?

0.146.0

What subscription do you have?

enterprise

Which model were you using?

_No response_

What platform is your computer?

Darwin 25.6.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

Ghostty

Codex doctor report

{
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  "generatedAt": "1785504290s since unix epoch",
  "overallStatus": "ok",
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      "status": "ok",
      "summary": "background server is not running",
      "details": {
        "control socket": "/Users/greeve/.codex/app-server-control/app-server-control.sock",
        "daemon state dir": "/Users/greeve/.codex/app-server-daemon",
        "mode": "ephemeral",
        "pid file": "/Users/greeve/.codex/app-server-daemon/app-server.pid (missing)",
        "settings": "/Users/greeve/.codex/app-server-daemon/settings.json (missing)",
        "status": "not running",
        "update-loop pid file": "/Users/greeve/.codex/app-server-daemon/app-server-updater.pid (missing)"
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      "category": "auth",
      "status": "ok",
      "summary": "auth is configured",
      "details": {
        "auth file": "/Users/greeve/.codex/auth.json",
        "auth storage mode": "File",
        "stored API key": "false",
        "stored ChatGPT tokens": "true",
        "stored agent identity": "false",
        "stored auth mode": "chatgpt"
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      "durationMs": 0
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        "config.toml": "/Users/greeve/.codex/config.toml",
        "config.toml parse": "ok",
        "cwd": "/Users/greeve/Developer/bi-bdp-validator",
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        "feature flag overrides": "none",
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        "log dir": "/Users/greeve/.codex/log",
        "mcp servers": "0",
        "model": "gpt-5.6-terra",
        "model provider": "openai",
        "sqlite home": "/Users/greeve/.codex"
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    "git.environment": {
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        "PATH git #1": "/usr/bin/git",
        "PATH git entries": "1",
        "git branch": "master",
        "git build options": "git version 2.50.1 (Apple Git-155); cpu: arm64; no commit associated with this build; sizeof-long: 8; sizeof-size_t: 8; shell-path: /bin/sh; feature: fsmonitor--daemon; libcurl: 8.7.1; zlib: 1.2.12; SHA-1: SHA1_DC; SHA-256: SHA256_BLK",
        "git exec path": "/Applications/Xcode.app/Contents/Developer/usr/libexec/git-core",
        "git version": "git version 2.50.1 (Apple Git-155)",
        "repo detected": "true",
        "repo root": "/Users/greeve/Developer/bi-bdp-validator",
        "selected git": "/usr/bin/git"
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    "installation": {
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        "managed by bun": "false",
        "managed by npm": "false",
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    "mcp.config": {
      "id": "mcp.config",
      "category": "mcp",
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      "summary": "active provider endpoints are reachable over HTTP",
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        "ChatGPT base URL": "https://chatgpt.com/backend-api/ reachable (HTTP 403)",
        "reachability mode": "ChatGPT auth"
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      "summary": "Responses WebSocket handshake succeeded",
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        "auth mode": "chatgpt",
        "connect timeout": "15000 ms",
        "endpoint": "wss://chatgpt.com/backend-api/<redacted>",
        "handshake result": "HTTP 101 Switching Protocols",
        "model provider": "openai",
        "models etag present": "true",
        "provider name": "OpenAI",
        "proxy env vars": "none",
        "reasoning header": "false",
        "server model present": "false",
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      "status": "ok",
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      "details": {
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        "current executable": "/opt/homebrew/bin/codex",
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        "version": "0.146.0"
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    "sandbox.helpers": {
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      "status": "ok",
      "summary": "sandbox configuration is readable",
      "details": {
        "approval policy": "OnRequest",
        "codex-linux-sandbox helper": "none",
        "execve wrapper helper": "/Users/greeve/.codex/tmp/arg0/codex-arg0VvjCRl/codex-execve-wrapper",
        "filesystem sandbox": "restricted",
        "network sandbox": "restricted"
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      "remediation": null,
      "durationMs": 0
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    "state.paths": {
      "id": "state.paths",
      "category": "state",
      "status": "ok",
      "summary": "state paths and databases are inspectable",
      "details": {
        "CODEX_HOME": "/Users/greeve/.codex (dir)",
        "active rollout files": "1 files, 53539 total bytes, 53539 average bytes",
        "archived rollout files": "0 files, 0 total bytes, 0 average bytes",
        "goals DB": "/Users/greeve/.codex/goals_1.sqlite (file)",
        "goals DB integrity": "ok",
        "log DB": "/Users/greeve/.codex/logs_2.sqlite (file)",
        "log DB integrity": "ok",
        "log dir": "/Users/greeve/.codex/log (missing)",
        "memories DB": "/Users/greeve/.codex/memories_1.sqlite (file)",
        "memories DB integrity": "ok",
        "sqlite home": "/Users/greeve/.codex (dir)",
        "state DB": "/Users/greeve/.codex/state_5.sqlite (file)",
        "state DB integrity": "ok",
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        "rollout DB active files": "1",
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        "rollout DB missing active rows": "0",
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        "rollout DB model providers": "openai=1",
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      "summary": "OS language en-US",
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    "updates.status": {
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      "status": "ok",
      "summary": "update configuration is locally consistent",
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        "latest version": "0.146.0",
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        "version cache": "/Users/greeve/.codex/version.json"
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  }
}

What issue are you seeing?

When starting Codex without command-line arguments, the configured
default model in ~/.codex/config.toml is ignored.

~/.codex/config.toml

``` toml
model = "gpt-5.6-terra"
model_reasoning_effort = "high"
service_tier = "default"

The CLI always starts with:

``` text
gpt-5.6-sol   medium   fast

even though both the user-level and project-level configuration specify
different defaults.

Interestingly:

• model_reasoning_effort is honored when the model is explicitly

selected with -m.

• codex -m <model> works correctly.
• The startup path without -m appears to ignore the configured

model and service_tier.

What steps can reproduce the bug?

1. Configure:

``` toml
model = "gpt-5.6-terra"
model_reasoning_effort = "high"
service_tier = "default"

2.  Ensure:
    -   no `CODEX_*` environment variables
    -   no project-local config (or create one with the same settings)
    -   fresh `~/.codex` directory
3.  Run:

``` bash
codex

What is the expected behavior?

Startup banner uses the configured defaults:

``` text
model: gpt-5.6-terra high default

(or at least `gpt-5.6-terra high` if `service_tier` is intentionally
overridden).

### Additional information

Running:

``` bash
codex -m gpt-5.6-terra

starts correctly as:

``` text
model: gpt-5.6-terra high fast

Running:

``` bash
codex -m gpt-5.5

starts correctly as:

``` text
model: gpt-5.5 high fast

This indicates:

-   `-m` correctly overrides the model.
-   `model_reasoning_effort = "high"` is being read from configuration.
-   The default startup path ignores the configured `model`.
-   `service_tier = "default"` also appears to be ignored.

## Troubleshooting Performed

-   Fresh `~/.codex` directory
-   Recreated `config.toml`
-   Deleted prior sessions/state
-   No project-local config initially
-   Tested with a project-local config
-   No `CODEX_*` environment variables
-   Installed via Homebrew
-   `/model` changes do not persist across restarts
-   `codex -m <model>` works correctly

Is this expected behavior for users authenticated through a managed
ChatGPT workspace (where workspace defaults override local
configuration), or is the CLI expected to honor the `model` and
`service_tier` values from `config.toml`?