[5/5] Move reasoning effort into step context

[aibrahim-oai]

Why

Reasoning effort is consumed by request-scoped work, but it is currently stored on the longer-lived TurnContext. With the captured step now propagated through sampling, compaction, guardian, and execution paths, the value can travel with the request snapshot that uses it.

What changed

• Move reasoning_effort and the effective-effort helpers from TurnContext to StepContext.
• Initialize the step value from the turn config when the step is captured.
• Redirect request, rollout, guardian, analytics, tracing, MCP metadata, and test reads to the step-owned value.
• Preserve the existing policy at each call site: model requests and rollout effort remain raw, while tracing and MCP metadata remain effective/defaulted. The task span is created before a step exists, so it computes the same prior effective tracing value from turn config.

Stacked on #31736. This is PR 5 of 5 and intentionally does not normalize raw effort to effective effort.

Validation

• cargo check -p codex-core --tests --message-format short

[aibrahim-oai]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Swish!

Reviewed commit: e769b785b3

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[aibrahim-oai]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Breezy!

Reviewed commit: c42baf6b53

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[aibrahim-oai]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: 291ee9387c

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[aibrahim-oai]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Chef's kiss.

Reviewed commit: 91dcea3bbe

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[aibrahim-oai]

Migrated to https://github.com/openai/codex-internal/pull/1673 following the codex-internal cutover. Please continue review there; this public PR is superseded.