## What
- Add a small extension capability for injecting model-visible response
items into the active turn
- Have the goal extension inject hidden goal-context steering when
tool-finish accounting reaches `BudgetLimited`
- Cover the extension backend path with an assertion on the injected
steering item
## Why
PR #23696 persists and emits the budget-limited goal update from
tool-finish accounting, but it leaves the model unaware of that
transition. The existing core runtime steers the model to wrap up in
this case; the extension path should do the same through an explicit
host capability.
## Testing
- `just fmt`
- `cargo test -p codex-goal-extension`
- `cargo test -p codex-extension-api`
## Why
`ContextualUserFragment` needs to be usable behind `dyn` for render-only
paths, but associated constants made the trait non-object-safe.
## What changed
- Replaced associated constants with trait methods so `dyn
ContextualUserFragment` can render fragments.
- Preserved the existing typed `T::matches_text(text)` registration
pattern via `type_markers()`.
- Kept default `render()` on the main trait so implementations only
provide role, markers, and body.
- Added unit coverage for rendering a `Box<dyn ContextualUserFragment>`.
## Verification
- `cargo test -p codex-core contextual_user_fragment_is_dyn_compatible`
- `just fix -p codex-core`
## Summary
This PR updates the goal continuation prompt to address feedback from
early adopters. There are two primary changes:
1. Goal continuation and budget-limit steering prompts now use hidden
user-context messages instead of hidden developer messages.
2. The goal continuation prompt is refined to improve the model's
ability to fully complete the active goal rather than stop at a smaller
or merely passing subset.
The user-message transition is important for two reasons. First, it
eliminates an issue where older steering messages could be responded to
again after a new turn. Second, it works better with compaction because
user messages are treated differently from developer messages during
compaction.
The prompt refinements make persistence explicit, ground work in current
evidence, encourage `update_plan` for multi-step progress visibility,
and require stronger completion audits before calling `update_goal`. It
also removes the elapsed-time reporting in the prompt; I saw evidence
that this was causing the model to shortcut work as it became nervous
about time.
These changes were tested with evals. Chriss4123 has also been running
independent evals in
[#19910](https://github.com/openai/codex/issues/19910), and many of the
improvements in this PR were suggested by him.
## Verification
- Tested with evals.
- Added and updated focused `codex-core` coverage for hidden goal user
context, continuation and budget-limit request shape, prompt rendering,
and objective delimiter escaping.
jif-oai