## Why
Image edits should use the exact images selected by the model instead of
inferring edit inputs from conversation history.
## What changed
- Replaced the image tool's `action` argument with optional
`referenced_image_paths`.
- Treats omitted or empty references as generation and populated
references as editing.
- Reads referenced absolute image paths and packages them as image data
URLs for the edit request.
- Removed the previous history-selection and image-count heuristics.
- Updated direct and code-mode tool instructions and calls.
- Added an app-server integration test covering an attached image routed
to the image edit endpoint.
## Validation
- Tested end-to-end on local `just codex` with copy pasted image,
attached image, etc.
- `just test -p codex-image-generation-extension`
- `just test -p codex-app-server
standalone_image_edit_uses_attached_model_visible_image`
- `just fix -p codex-image-generation-extension`
- `just bazel-lock-check`
## Summary
Responses Lite does not execute hosted Responses tools, so models using
it must route web search and image generation through Codex-owned
executors & standalone Response's API endpoints.
This PR is stacked on #26487.
## Validation
- `cargo test -p codex-core responses_lite_ --lib`
- `cargo test -p codex-core
standalone_executors_remain_hidden_without_flags_or_responses_lite
--lib`
- `cargo test -p codex-core
hosted_tools_follow_provider_auth_model_and_config_gates --lib`
- `cargo test -p codex-web-search-extension -p
codex-image-generation-extension`
- `cargo test -p codex-app-server --test all standalone_`
- `cargo fmt --all -- --check`
## Why
Standalone image generation returns image bytes to the model, but the
model also needs the host artifact path to reference the generated file
in follow-up work.
## What changed
- Append the default saved-image path hint alongside the generated image
tool output.
- Reuse the existing core image-generation hint text.
- Pass the thread ID and Codex home directory needed to compute the
artifact path.
- Add app-server and extension coverage for the model-visible hint.
## Validation
- `just fmt`
- `just bazel-lock-check`
- `just test -p codex-app-server
standalone_image_generation_returns_saved_path_hint_to_model`
## Why
The standalone `image_gen.imagegen` extension should behave like native
image generation for artifact persistence and UI completion, while
returning its save-location guidance as part of the tool result instead
of injecting a developer message.
## What Changed
- Added an image-generation completion hook for extension tools so core
can persist generated images and emit the existing `ImageGeneration`
lifecycle events.
- Reused core image artifact persistence for extension output and
removed extension-local save-path/file-writing logic.
- Split shared image persistence from built-in finalization so native
image generation keeps its existing developer-message instruction
behavior.
- Returned the generated image save-location instruction through the
extension `FunctionCallOutput`, alongside the generated image input for
model follow-up.
- Preserved the existing image-generation event shape for current UI and
replay compatibility.
- Avoided cloning the full generated-image base64 payload when emitting
the in-progress image item.
- Removed dependencies no longer needed after moving persistence out of
the extension crate.
## Fast Follow
- Adjust the existing Extension API and add a general `TurnItem`
finalization path for re-usability of code
## Validation
- Ran `just fmt`.
- Ran `just bazel-lock-update`.
- Ran `just bazel-lock-check`.
- Ran `just test -p codex-tools -p codex-extension-api -p
codex-image-generation-extension`.
- Ran `just test -p codex-core
image_generation_publication_is_finalized_by_core`.
- Ran `just test -p codex-core
handle_output_item_done_records_image_save_history_message`.
- Ran `just fix -p codex-tools -p codex-extension-api -p codex-core -p
codex-image-generation-extension`.
## Why
Add a standalone image generation path that can be exercised
independently of hosted Responses image generation, while retaining the
hosted tool as fallback unless the extension is actually available to
the model.
## What changed
- Added the `codex-image-generation-extension` crate with standalone
generate/edit execution, prior-image selection for edits, model-visible
image output, and local generated-image persistence.
- Installed the extension in app-server behind the disabled-by-default
`imagegenext` feature and backend eligibility checks.
- Updated core tool planning so eligible `image_gen.imagegen` exposure
replaces hosted `image_generation`, while unavailable configurations
retain hosted fallback.
- Added coverage for extension behavior, edit history reuse, feature
gating, auth eligibility, and hosted-tool replacement.
- The extension is installed through app-server only in this PR; other
execution paths retain hosted image generation because hosted
replacement occurs only when the standalone executor is actually
registered and model-visible.
- The initial extension contract intentionally fixes the image model to
`gpt-image-2` and uses automatic image parameters.
- Native generated-image history/card parity and rollout persistence
cleanup are intentionally deferred follow-up work.
## Validation
- `just test -p codex-image-generation-extension`
- `just test -p codex-features`
- `just test -p codex-core
hosted_tools_follow_provider_auth_model_and_config_gates`
- `just test -p codex-app-server`
- `just fix -p codex-image-generation-extension -p codex-features -p
codex-core -p codex-app-server`
- `just fmt`
- `just bazel-lock-update`
- `just bazel-lock-check`
---------
Co-authored-by: jif-oai <jif@openai.com>
