Widen the salvaged Image API hunk (#114340) to the whole class:
- plugins/image_gen/_common.py: record_token_usage() — one helper feeding the
aux accounting chokepoint (agent.aux_accounting.record_aux_usage) with task
"image_generation", the billing provider and the priced model id. Dict and
SDK usage objects alike; a body without tokens is a no-op, as is a call
outside a turn.
- plugins/image_gen/openrouter: the /chat/completions path (the DEFAULT model
chain — openai/gpt-5.4-image-2, google/gemini-3-pro-image — is chat-only and
token-billed) now records too; the Image API path uses the shared helper
(the contributor's local _record_image_api_usage is folded into it) and both
pass base_url so pricing resolves the route. Task renamed image_gen ->
image_generation to match the other aux task names.
- plugins/image_gen/openai: gpt-image bills per text/image token; record the
Images API usage block under the API model (gpt-image-2), not the Hermes
quality-tier label.
- FAL, xAI, Krea, DeepInfra, Meta, openai-codex return no token usage and stay
unrecorded (nothing to bill per token).
- tests: the contributor's two tests folded into one invariant parametrized
over chat / Image API / no-usage control; one OpenAI invariant.
- docs: image-generation.md "How It Works Internally" gains the accounting step.
Fixes#114324
6babdc96b8