## Why
Standalone image generation emitted a started item but no terminal item
when the backend failed. Clients could leave the operation unresolved or
render it as successful.
## What changed
- Emit a terminal image-generation item with `status: "failed"` when
generation or editing fails.
- Skip image persistence for failed terminal items.
- Render failed image generation distinctly in TUI history.
- Preserve the status when handling live and replayed terminal items.
## Looks for TUI, App-Side change needed
<img width="867" height="89" alt="image"
src="https://github.com/user-attachments/assets/9e32342f-a982-411e-8498-456639fc468a"
/>
## Validation
- `just test -p codex-image-generation-extension`
- App-server image-generation tests
- Core stream-event tests
- TUI image-generation lifecycle and snapshot tests
- Scoped Clippy and formatting
## Why
Image generation used `std::fs::read` for referenced image paths, which
did not support environment-backed filesystems or their sandbox context.
## What changed
- Expose optional turn environments to extension tool calls.
- Include each environment’s ID, working directory, filesystem, and
sandbox context.
- Read referenced images through the selected environment filesystem.
- Keep sandbox usage at the extension call site so extensions can choose
the appropriate access mode.
- Consolidate image request construction into one async function.
- Add coverage for successful environment reads and read failures.
## Validation
- `cargo check -p codex-image-generation-extension --tests`
- `just fmt`
- `just bazel-lock-update`
- `just bazel-lock-check`
`just test -p codex-image-generation-extension` could not complete
because the build exhausted available disk space.
## 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`
## 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`
## Summary
Restore Windows coverage for standalone image generation in code mode.
The previous test executed a V8-backed code-mode cell on Windows CI,
where that runtime path is intentionally excluded because it is
unreliable. The test was then ignored entirely on Windows, removing
useful coverage.
This splits the test into two checks:
- All platforms verify that `image_gen__imagegen` is exposed to the
model when image generation is configured for code mode only.
- Non-Windows platforms continue to execute the full V8-backed flow and
verify that the nested image-generation call succeeds.
## Verification
- `just fmt`
- `git diff --check`
- `just test -p codex-app-server standalone_image_generation`
Result: 3 tests passed, plus the required bench smoke check.
## Why
Standalone image generation remained top-level-only in code-mode
sessions.
## What changed
- Change imagegen exposure from `DirectModelOnly` to `Direct`.
- Keep direct-mode access while enabling nested code-mode access.
- Add a focused regression test for the exposure contract.
## Validation
- `just test -p codex-image-generation-extension`
Won Park