[aiapienthusiast]

Problem

ORG2 has no built-in entry for Cheaper Inference.
Cheaper Inference is an OpenAI-compatible LLM gateway.
One API key gives access to models from several labs.
Today a user must use the generic Custom provider and type the base URL and protocol by hand.

Solution

Add cheaperinference_api as an API key provider.
It uses the same pattern as #503 (Atlas Cloud) and the current CherryIN registry shape.

• Key vault: ModelType::CheaperinferenceApi, registry entry, endpoint table, protocols (openai default, anthropic optional), env var CHEAPERINFERENCE_API_KEY.
• Validation: OpenAI-compatible validator path; listed with providers that have no public quota API.
• Agent core: provider_id::CHEAPERINFERENCE, ProviderSpec, model type mapping, auxiliary model fallback list.
• Frontend: schema literal, provider lists, icon mapping.

Endpoints

• OpenAI protocol: https://api.cheaperinference.com/v1
• Anthropic protocol: https://api.cheaperinference.com (/v1/messages)
• Docs: https://cheaperinference.com/docs

Potential risks

• The Rust crates were not compiled locally (see Verification). Every new match arm sits next to the existing CherryinApi arm, so match exhaustiveness is the same as for CherryIN.
• No brand icon is added. The tile uses the existing generic gateway icon (custom). A brand SVG can follow in a separate change.
• No CLI agent pairing is added (Claude Code, OpenCode). Only the Rust harness uses the provider. This keeps the change small.
• No screenshots: the tile is rendered by the existing registry-driven key vault UI; no layout or component changed.
• No data migration. Existing keys and settings are not touched. Rollback is a plain revert.

Verification

• rustfmt --edition 2021 --check on all 11 changed Rust files: pass.
• Searched every CherryinApi / cherryin_api / provider_id::CHERRYIN use and added the new provider next to each one.
• Changed .ts files stay under 700 lines (largest: 598).
• Not run: cargo test for key_vault and agent_core, pnpm typecheck, pnpm lint:fast, app build. Reviewers or CI should run them.
• Added test coverage in existing tests: api_providers_are_api_key_providers, as_str_round_trips_through_from_str, new_aggregators_are_openai_and_anthropic_capable, every_key_vault_model_type_maps_to_a_registered_provider_spec.

Submit checklist

• I read and followed .github/PR_RULES.md.
• The PR is focused and has a scoped Conventional Commit title, such as feat(scope): summary or fix(scope): summary.
• I ran the relevant checks, or explained why they were not run.
• No secrets, private config, generated output, or unrelated formatting changes are included.
• Docs, screenshots, and locale updates are included when the change needs them.