## Why
The model-visible `<network>` context currently repeats indentation and
a pair of XML tags for every allowed or denied domain. Large domain sets
spend a surprising amount of prompt budget on that scaffolding instead
of the actual policy values.
## What changed
- Render allowed domains as one comma-separated `<allowed>` value
instead of one element per domain.
- Render denied domains the same way.
- Keep the full allow/deny domain sets model-visible while updating the
serialization and settings-update coverage for the denser shape.
## Example
Before:
```xml
<network enabled="true">
<allowed>api.example.test</allowed>
<allowed>cdn.example.test</allowed>
<denied>blocked.example.test</denied>
</network>
```
After:
```xml
<network enabled="true"><allowed>api.example.test,cdn.example.test</allowed><denied>blocked.example.test</denied></network>
```
## Validation
- `cargo test -p codex-core environment_context`
- `cargo test -p codex-core
build_settings_update_items_emits_environment_item_for_network_changes`
- Ran a local `codex` session with a real network context containing 121
allowed domains and 42 denied domains, then inspected the raw prompt
with `raw_token_viewer_cli.py`. With the same domain set, the rendered
`<network>` section shrank from 7,175 characters across 161 lines to
3,666 characters on one line, and the containing environment-context
block fell from 6,428 tokens to 5,379 tokens.
## Summary
- make resolved turn environment shell metadata optional instead of
hard-coding bash
- render environment context shells from explicit environment metadata
when present, falling back to the existing session shell
- update environment context tests for inherited PowerShell-style
fallback and explicit per-environment shell override
## Testing
- Not run (not requested; formatted with `just fmt`).
Co-authored-by: Codex <noreply@openai.com>
## Why
This is a prep PR in the multi-environment process-tool stack. It
separates ownership/config cleanup from the behavior change that teaches
process tools to route by selected environment, so the follow-up PR can
focus on model-facing `environment_id` behavior.
## Stack
1. https://github.com/openai/codex/pull/20646 - `EnvironmentContext`
rendering for selected environments
2. https://github.com/openai/codex/pull/20669 - selected-environment
ownership and tool config prep (this PR)
3. https://github.com/openai/codex/pull/20647 - process-tool
`environment_id` routing
## What Changed
- keep the resolved turn environment list wrapped in
`ResolvedTurnEnvironments` through `TurnContext` instead of unwrapping
it back to a raw `Vec`
- add `TurnContext::resolve_path_against` so cwd-relative path
resolution has one shared helper
- replace the old tool config boolean with `ToolEnvironmentMode::{None,
Single, Multiple}`
## Testing
- Tests not run locally; this prep refactor is covered by GitHub CI for
the stack.
Co-authored-by: Codex <noreply@openai.com>
## Why
The model needs a way to see which environments are available during a
multi-environment turn without changing the legacy single-environment
prompt surface or pulling replay/persistence changes into the same
review.
## Stack
1. https://github.com/openai/codex/pull/20646 - `EnvironmentContext`
rendering for selected environments (this PR)
2. https://github.com/openai/codex/pull/20669 - selected-environment
ownership and tool config prep
3. https://github.com/openai/codex/pull/20647 - process-tool
`environment_id` routing
## What Changed
- extend `environment_context` so multi-environment turns render an
`<environments>` block with the selected environment ids and cwd values
- keep zero- and single-environment turns on the existing cwd-only
render path
- keep replay and persistence paths on the legacy surface for now so
this PR stays scoped to live prompt rendering
- add focused coverage in
`codex-rs/core/src/context/environment_context_tests.rs`
## Testing
- CI
---------
Co-authored-by: Codex <noreply@openai.com>
sayan-oai ·
starr-openai ·
pakrym-oai ·