fix(app): built-in image tool unavailable on Images 2.5 rollout day

Summary

On September 8, 2026, a Codex desktop task could load the bundled imagegen skill but had no callable built-in image-generation tool. An ordinary request to generate a comic from an attached reference image therefore produced no image and led the assistant to suggest a separate API-key-based fallback.

This report records the failure on the day OpenAI announced Images 2.5 availability in Codex. It does not establish that Images 2.5 introduced the failure. Related issue #40248 reported the same visible symptom before this launch; this may be a continuation of that problem.

Steps to reproduce

The following sequence was observed in one projectless Codex desktop task:

1. Attach a reference comic illustrating the six possible priority orderings of Asimov's Three Laws of Robotics.
2. Ask Codex to generate a new image retaining the six orderings and end-state labels, with new humorous illustrations showing their consequences.
3. The assistant loads the bundled imagegen skill, which directs it to use the built-in image-generation tool by default without an API key.
4. The assistant inspects the callable tools exposed to the session and the available deferred-tool inventory. No built-in image-generation tool is exposed.
5. No generation call is made and no image is returned. The assistant asks whether to switch to the CLI/API fallback requiring OPENAI_API_KEY.
6. Supply the September 8 Images 2.5 announcement and ask the assistant to verify the official documentation using the openai-docs skill. It confirms the documented capability but remains unable to call the built-in generator in the same task.

Reproduction gap: this has not been reproduced in a second task or independently traced in backend logs. The smallest missing diagnostic is the effective image-generation capability decision for the affected task, including whether account eligibility, model support, configuration, or rollout state caused the tool to be omitted. No specific cause is established.

Expected behavior

For an eligible Codex session, a normal image request with an attached reference should invoke built-in image generation and return an image through the documented Codex workflow, without requiring separate API credentials. If this session is ineligible or has not received the rollout, an explicit availability reason should make that limitation diagnosable.

Closure signal: in the affected environment, repeat an ordinary reference-image generation request and verify that a built-in image-generation call produces a visible image. If capability is intentionally unavailable, verify an explicit, accurate eligibility or rollout explanation rather than an unexplained skill/tool mismatch.

Actual behavior

The imagegen instructions were available, but their preferred built-in tool was absent from the session's callable tool set. The assistant could only describe a proposed comic and suggest an API fallback. There was no image-generation response, HTTP error from the image service, or generated artifact because no built-in generation call could be made.

Affected area

Codex desktop image-generation availability in a projectless task. This report concerns access to the built-in generation workflow; it does not establish an image-model quality or API failure.

Runtime or environment

• Date observed: September 8, 2026, America/Vancouver.
• Surface: Codex desktop app, local projectless task.
• Platform reported by uname -mprs: Darwin 25.6.0 arm64 arm.
• Conversation model identified in session context: GPT-6 Astra.
• App version/build: not verified; no version is inferred from a separate CLI installation.
• Subscription tier, effective authentication mode, image-generation entitlement, and rollout assignment: not verified in this report.
• Scope of observation: one task across multiple follow-up requests; no prior successful baseline, restart test, or independent fresh-task reproduction.

Evidence

The assistant loaded the bundled imagegen skill, whose documented default is the built-in image-generation tool and whose instructions explicitly state that this route does not require OPENAI_API_KEY. Inspection of the exposed tool inventory found no callable built-in generator. This is session-level evidence, not a backend capability trace.

The September 8 launch announcement states: "Images 2.5 is rolling out today to ChatGPT, ChatGPT Work, and Codex users across all tiers on desktop, mobile, and web."

The official image-generation guide, fetched during the task, instructs desktop users to ask for an image from the app composer and add a reference image as visual guidance. It also documents invoking the imagegen skill explicitly and says built-in generation counts toward Codex usage limits.

That how-to guide still named gpt-image-2 when fetched, whereas the API image-generation guide already listed gpt-image-2.5-flare and gpt-image-2.5-sunburst. This documentation discrepancy is context only; it does not prove which model this task should have received or explain the missing tool.

Impact

A user following the advertised image-generation workflow cannot obtain the requested image. The assistant redirects the user toward a separately billed API workflow despite the documented built-in option, and neither the user nor the assistant receives a concrete reason for the missing capability.

Additional context

Related: #40248, "Built-in imagegen skill is available, but the image_gen tool is not exposed in Codex App," opened before the Images 2.5 launch. This new report adds a September 8 observation, the GPT-6 Astra session context, and the current rollout/documentation references. Maintainers may determine that both reports have the same cause; this report does not claim an independently verified Images 2.5 regression.

Start with the Codex desktop projectless task and the exposed callable/deferred-tool inventory; compare the bundled imagegen skill's expected built-in route with the effective image-generation capability decision. Done means reproducing the request with a visible built-in image, or reporting an explicit, accurate eligibility or rollout reason when unavailable.