[Felixkw12]

Summary

• add Opper as a built-in OpenAI-compatible provider alias (opper, base URL https://api.opper.ai/v3/compat), in the same shape as the OpenRouter alias
• discover OPPER_API_KEY for automatic model selection and credential forwarding, with claude-sonnet-4-6 as the default model
• merge consecutive system messages, like the other gateway aliases
• document inline and named-model configuration, add an example recipe, and list the provider in navigation, the alias table and the schema description

Opper is an EU-hosted AI gateway: 700+ models from 50+ providers behind one OpenAI-compatible API, with one key. The models.dev catalog already carries the opper provider (it is in pkg/modelsdev/snapshot.json), so the default model and the example resolve through it and no catalog exemption is needed.

Testing

• Not run locally. The new rows mirror the existing alias, auto-config and system-message merge tests, so CI is the first run of go test, lint and the docs build.
• The default model and the example model are pool names checked against Opper's public catalogue (GET https://api.opper.ai/v3/models) and the embedded models.dev snapshot.

Disclosure: Opper is my startup.

[aheritier]

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[Felixkw12]

Thanks for the approval. The commit is now signed and verified by GitHub (afb8dac). Same tree as before, no content changes.

[Copilot]

🟢 Approval recommended

The changes follow established alias patterns with no unresolved findings; test execution remains unverified.

No open issues 🎉

What changed in this PR

Adds Opper as a built-in OpenAI-compatible provider using the existing alias infrastructure.

Changes:

• Registers Opper’s endpoint, API key discovery, and default model.
• Enables consecutive system-message merging and adds regression tests.
• Adds configuration documentation, navigation, and an example.

File	Description
pkg/​model/​provider/​openai/​system_message_merge_test.go	Tests Opper message merging.
pkg/​model/​provider/​openai/​client.go	Enables gateway message merging.
pkg/​model/​provider/​aliases.go	Registers the Opper alias.
pkg/​model/​provider/​aliases_test.go	Verifies alias settings.
pkg/​config/​auto.go	Adds credential discovery and default model.
pkg/​config/​auto_test.go	Tests automatic Opper selection.
examples/​README.md	Lists the Opper example.
examples/​opper.yaml	Provides a sample agent configuration.
docs/​providers/​overview/​index.md	Lists Opper authentication.
docs/​providers/​opper/​index.md	Documents setup and usage.
docs/​data/​nav.yml	Adds provider navigation.
docs/​configuration/​models/​index.md	Lists Opper in configuration guidance.
agent-schema.json	Adds Opper to the provider description.

_{Review effort: Balanced}