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Codex CLI v0.165 makes Vertex AI a built-in provider and turns memories on by default

#codex #codexcli #updates #vertexai

Originally published at https://aicoding-guide.com.

Codex CLI v0.165.0 brings six features and six fixes. Two of them touch configuration: a built-in Vertex AI provider and memories on by default.

For both, the release notes are ahead of the official configuration reference. Check the behaviour on your own machine before relying on either.

Key point
What this article covers

  • The Vertex AI provider configured with model_provider = "gcp"
  • Why the release notes and the configuration reference disagree about memories
  • Changing reasoning effort partway through a conversation

Vertex AI is now a built-in provider

The release notes read: "Added a built-in Google Cloud Vertex AI provider, configured with model_provider = "gcp"." Using Vertex AI previously meant writing your own model_providers entry; now it is treated as built in.

gcp is not in the configuration reference yet
As of 2026-10-30, the reference lists only three built-in provider IDs: "Built-in provider IDs (openai, ollama, and lmstudio) are reserved and cannot be overridden." There is no mention of gcp or Vertex AI. The ID appears only in the release notes.

Where you write the setting matters. The configuration reference states that model_provider and model_providers are ignored in a project-local .codex/config.toml.

# Put this in ~/.codex/config.toml; a project-local copy is ignored
model_provider = "gcp"
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The ignored keys include openai_base_url, chatgpt_base_url, model_provider, model_providers, notify, profile, profiles and otel. Provider, notification and telemetry keys belong in user-level config. For defining a custom provider, the fields are model_providers.<id>.name, .base_url, .env_key and others, covered in Configuring Codex with config.toml.

GPT-6.1 Terra was also added to the model catalogs.

Memories are on by default for fresh profiles

The release notes read: "Enabled memory v2 by default for fresh profiles and added support for importing external-agent memories into it."

The two sources disagree on the default
The configuration reference still describes features.memories as "Enable Memories (off by default)" (checked 2026-10-30). The term "memory v2" does not appear in the memories documentation at all. Since the documents do not settle which applies, check the actual state with /memories.

The mechanism itself is documented.

Aspect Detail
Storage ~/.codex/memories/, holding summaries, durable entries, recent inputs and evidence
When they are written In the background once a chat has been idle long enough, not at the end of every chat
What is skipped Active and short-lived sessions; secrets are redacted from generated memory fields
Throttling A background pass is skipped when your rate-limit remaining percentage is below the configured threshold
Per-chat control /memories chooses whether the chat can use existing memories and whether it feeds future ones

The documentation is also explicit about the limits of relying on them: "Keep required team guidance in AGENTS.md or checked-in documentation. Treat memories as a helpful recall layer, not as the only source for rules that must always apply."

On the files themselves, it says "Treat these files as generated state" — fine to inspect when troubleshooting or before sharing your Codex home directory, but not a control surface to edit by hand.

Reasoning effort can change mid-conversation

Another entry reads: "Enabled reasoning effort changes during a conversation by default for supported models." On models that support it, you can change the depth after a conversation has started.

Switching through /model already existed; what changed is that mid-conversation changes are enabled by default. For the values and the ways to set them, see How to change reasoning effort in Codex CLI.

The session picker also gained a repository filter, and the agent command center now groups by directory, which makes sessions easier to find across linked worktrees.

Security and the other fixes

There are six fixes. The security one reads: "Closed a marketplace URL validation gap that could allow Git to connect to a different host than the one checked against allowed patterns."

The remaining fixes that change behaviour:

  • Fresh TUI sessions now honour the server's default approval reviewer when no explicit override is given
  • TUI preferences stay editable and immediately applicable when execution settings are invalid
  • Queued agent messages no longer restart work after an interrupt or a switch to Plan mode
  • When a provider reports that a model was not found, Codex stops retrying and preserves the error message

For the previous release, see Codex CLI v0.164 adds /presets and inline /permissions arguments.

Summary

  • A built-in Vertex AI provider is configured with model_provider = "gcp"
  • gcp could not be confirmed in the configuration reference, which still lists only openai, ollama and lmstudio
  • model_provider is ignored in a project-local .codex/config.toml; put it in user-level config
  • Memories are said to be on by default for fresh profiles, while the reference still says off by default
  • A marketplace URL validation gap that could redirect Git to another host was closed

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