## Why Standalone image-generation extensions emitted turn items through the low-level event path, bypassing host-owned finalization such as image persistence and contributor processing. At the same time, the generated-image save-path hint must remain visible to the model through the extension tool's `FunctionCallOutput`, rather than the legacy built-in developer-message path. ## What changed - Extended `ExtensionTurnItem` to support image-generation items while keeping the extension-facing emitter API limited to `emit_started` and `emit_completed`. - Routed extension completion through core `finalize_turn_item`, so standalone image-generation items receive host-owned processing and persisted `saved_path` values before publication. - Kept legacy built-in image generation on its existing developer-message hint path, while standalone image generation returns its deterministic saved-path hint in `FunctionCallOutput`. - Shared the image artifact path and output-hint formatting used by core and the image-generation extension. - Passed thread identity through extension tool calls so standalone image generation can construct the same intended artifact path as core. - Added an app-server integration test covering real standalone image generation, saved artifact publication, model-visible output hint wiring, and absence of the legacy developer-message hint. ## Validation - `just fmt` - `just test -p codex-image-generation-extension` - `just test -p codex-web-search-extension` - `just test -p codex-goal-extension` - `just test -p codex-memories-extension` - Targeted `codex-core` tests for image save history, extension completion finalization, and contributor execution - `just test -p codex-app-server standalone_image_generation_returns_saved_path_hint_to_model` - `just fix -p codex-core` - `just fix -p codex-image-generation-extension` - `just bazel-lock-update` - `just bazel-lock-check`
codex-tools
codex-tools is the shared support crate for building, adapting, and executing
model-visible tools outside codex-core.
Today this crate owns the host-facing tool models and helpers that no longer
need to live in core/src/tools/spec.rs or core/src/client_common.rs:
- aggregate host models such as
ToolSpec,ConfiguredToolSpec,LoadableToolSpec,ResponsesApiNamespace, andResponsesApiNamespaceTool - host discovery models used while assembling tool sets, including discoverable-tool models and request-plugin-install helpers
- host adapters such as schema sanitization, MCP/dynamic conversion, code-mode augmentation, and image-detail normalization
- shared executable-tool contracts such as
ToolExecutor,ToolCall, andToolOutput
That extraction is the first step in a longer migration. The goal is not to
move all of core/src/tools into this crate in one shot. Instead, the plan is
to peel off reusable pieces in reviewable increments while keeping
compatibility-sensitive orchestration in codex-core until the surrounding
boundaries are ready.
Vision
Over time, this crate should hold host-side tool machinery that is shared by multiple consumers, for example:
- host-visible aggregate tool models
- tool-set planning and discovery helpers
- MCP and dynamic-tool adaptation into Responses API shapes
- code-mode compatibility shims that do not depend on
codex-core - other narrowly scoped host utilities that multiple crates need
The corresponding non-goals are just as important:
- do not move
codex-coreorchestration here prematurely - do not pull
Session/TurnContext/ approval flow / runtime execution logic into this crate unless those dependencies have first been split into stable shared interfaces - do not turn this crate into a grab-bag for unrelated helper code
Migration approach
The expected migration shape is:
- Keep extension-owned executable-tool authoring in
codex-extension-api. - Move host-side planning/adaptation helpers here when they no longer need to
stay coupled to
codex-core. - Leave compatibility-sensitive adapters in
codex-corewhile downstream call sites are updated. - Only extract higher-level host infrastructure after the crate boundaries are clear and independently testable.
Crate conventions
This crate should start with stricter structure than core/src/tools so it
stays easy to grow:
src/lib.rsshould remain exports-only.- Business logic should live in named module files such as
foo.rs. - Unit tests for
foo.rsshould live in a siblingfoo_tests.rs. - The implementation file should wire tests with:
#[cfg(test)]
#[path = "foo_tests.rs"]
mod tests;
If this crate starts accumulating code that needs runtime state from
codex-core, that is a sign to revisit the extraction boundary before adding
more here.