Chronicle memory writer should expose model and cost controls

Title: Chronicle memory writer should expose model/cost controls instead of always using expensive background models

Summary

Codex Chronicle / memory generation appears to consume a large amount of Codex quota in the background. On my machine, the Chronicle memory writer is launched with --model gpt-5.5 --ignore-user-config, which means changing my normal Codex default model does not seem to reduce its cost.

This makes the feature feel risky to keep enabled: quota can drop quickly even when I am not actively sending prompts, and the app UI does not make it obvious that Chronicle/memory generation is responsible.

Why this is a problem

Chronicle is useful, but memory writing is a background feature. It should not silently use one of the most expensive models without giving the user control.

For many users, a smaller model would be good enough for summarizing screen/OCR context into memories. If high-quality memory writing needs a larger model, that should be an explicit choice rather than the only behavior.

Local evidence

While Chronicle was running, I observed background memory writer processes like:

codex exec --ephemeral --ignore-user-config --model gpt-5.5 ... \
  --config model_provider="openai-memgen" ... \
  --config model_providers.openai-memgen.http_headers={ "X-OpenAI-Memgen-Request" = "true" } ... \
  --cd $TMPDIR/chronicle/screen_recording -

I also observed a memory consolidation request shortly after quota reset:

model: gpt-5.4
cwd: ~/.codex/memories
total_usage_tokens: 143165
estimated_token_count: 138835

The output for that request said it completed incremental memory consolidation and updated:

~/.codex/memories/MEMORY.md
~/.codex/memories/memory_summary.md

This is consistent with the Chronicle docs saying background agents generate memories and currently consume rate limits quickly:

https://developers.openai.com/codex/memories/chronicle

Request

Please consider adding explicit controls for Chronicle / memory generation cost:

1. Let users choose the Chronicle memory writer model, for example a cheaper mini/small model.
2. Do not force gpt-5.5 with --ignore-user-config unless the user explicitly opts into that quality/cost level.
3. Show Chronicle/memory generation usage separately in the quota/usage UI.
4. Add a daily or hourly quota cap for background memory generation.
5. Provide a low-cost mode, for example "summarize less often" or "only generate memories while plugged in / manually triggered".

At minimum, users should be able to keep Chronicle enabled without unexpectedly burning a large fraction of their Codex quota.