fix(catalog): stop offering Codex-retired models on the OAuth path

[lucifer78907]

Type of Change

• Bug fix
• New feature
• Enhancement / refactor
• New skill
• Documentation
• CI / build

Description

Selecting gpt-5.4 after signing in with ChatGPT produced an agent that
failed on its first call. gpt-5.4 and gpt-5.4-mini retired from Codex
ChatGPT sign-in on 2026-08-31 (gpt-5.6-terra and gpt-5.6-luna are the
documented replacements), and nano tiers ship API-only and were never served
there. Both the CLI wizard and forge-ui still offered all of them for
browser-based OAuth login.

OpenAI states the API and API-key Codex are unaffected by those retirements,
so the retired models stay selectable with an API key — removing them
outright would break working setups.

Summary

• The CLI's OAuth/API-key split was fake — provider_step.go declared
  openAIOAuthModels and openAIAPIKeyModels but built both from the same
  unfiltered openAIModelOptions(). Two names, one list; the intent was
  there, the filtering never was.
• The catalog couldn't express the split — catalog.Model was
  {Label, ModelID}, leaving nowhere to record "API-key only", so the
  wizard could not have filtered even if it tried.
• forge-ui duplicated the entire OpenAI model list instead of reading
  the catalog — precisely the drift the catalog package doc says it exists
  to prevent. They had already diverged: forge-ui carried the 5.6 family,
  the catalog didn't.
• gpt-5.4 was hardcoded as the default in four independent places —
  the catalog, forge-ui, init.go's template data, and
  runtime/config.go's defaultModelForProvider. That last one means any
  agent whose forge.yaml omits a model was running on a retired model.
• The whole 5.6 family and gpt-6-astra were missing from the catalog
  entirely.

Changes

File	Change
forge-core/catalog/catalog.go	Model.APIKeyOnly, plus Provider.OAuthModels() / APIKeyModels()
forge-core/catalog/providers.go	Added gpt-6-astra + gpt-5.6-{sol,terra,luna}; marked gpt-5.4, gpt-5-mini, gpt-5-nano, gpt-4.1 as APIKeyOnly; DefaultModel → gpt-5.6-terra; fixed the stale description
forge-cli/internal/tui/steps/provider_step.go	Filters per auth method via the new accessors
forge-ui/handlers_create.go	Projects the OpenAI entry from the catalog instead of duplicating it, so the two cannot drift again
forge-core/runtime/config.go	Runtime default → gpt-5.6-terra
forge-cli/cmd/init.go	Reads catalog.DefaultModel instead of keeping its own switch

Deliberate exclusions. Pro-only gpt-5.3-codex-spark and
previous-generation gpt-5.5 are Codex OAuth models but are not offered:
codex-spark fails for non-Pro accounts, and gpt-5.5 is on a retirement path.
gpt-6-astra is offered despite a staged rollout, but is not the
default.

Behaviour change worth flagging: existing agents whose forge.yaml
omits a model move from gpt-5.4 to gpt-5.6-terra on next run. Correct
for OAuth users; a real change for API-key users, who could still use
gpt-5.4.

Open question for reviewers: gpt-5-mini and gpt-5-nano don't match
OpenAI's naming (the real ids appear to be gpt-5.4-mini /
gpt-5.4-nano), so they may be broken on the API-key path too. I left
the id strings untouched and only moved them to API-key-only rather than
guess — worth a second opinion.

General Checklist

• Tests pass for affected modules (go test ./...)
• Code is formatted (gofmt -w)
• Linter passes (golangci-lint run)
• go vet reports no issues
• No new egress domains added without justification

Notes on the unchecked boxes:

• gofmt -w deliberately not run — the working copy is CRLF, so it
  would rewrite every file in the module and bury the change. The diff was
  verified to contain no line-ending churn. Please confirm in CI.
• golangci-lint not installed locally, so it hasn't been run.
• Tests were run on Windows. forge-core/catalog, forge-core/runtime
  and TestBuildTemplateData_DefaultModels all pass. These forge-cli/cmd
  and forge-ui/uiconfig failures are pre-existing and environmental (Unix
  permission bits, executable bits, credential lookup) — confirmed by
  stashing the changes and re-running on a clean tree:
  TestResolveTryProvider_Ollama,
  TestResolveTryProvider_NoCredsNonInteractive,
  TestQuickstartPreset_ScaffoldsValidConfig,
  TestImportSkillFolder_FullFolder, TestSetEnvFileValue_*.

Tests added

• TestOpenAIOAuthModelsExcludeRetired — asserts no known-retired id
  appears in OAuthModels(), and that DefaultModel is itself
  OAuth-reachable, so the wizard can never hand an OAuth user a default that
  fails.
• TestDefaultModelForProvider and TestBuildTemplateData_DefaultModels
  updated for the new default.

Not addressed

anthropic, gemini and ollama model lists are still hardcoded in
forge-ui — the catalog holds no Models for them. Same drift risk, left for
a follow-up.

Related Issues

Reference: Codex models ·
Using Codex with your ChatGPT plan