[Feature]: Custom provider endpoint

[napoleonicleon-COWBLOB]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area

apps/web

Problem or use case

i want in provider settings a way to setup a custom provider other then modyfying opencode with custom model, to have my own harness in t3code, optimally have a setup with config file

Proposed solution

in the provider ssetup pane have like opencode a option to choose server port, and like it takews setup öodels, same thing would happen, and endpoitns etc explicited or a lnink to documentation

Why this matters

it allows working with t3code but with custom harness and local models in my case, may be obscure now but will become common in the future

Smallest useful scope

add a custom endpoint to point our harness and model to, just a preset port so we can have it, and maybe setup a custom icon etc and modes and effort etc

Alternatives considered

No response

Risks or tradeoffs

No response

Examples or references

No response

Contribution

• I would be open to helping implement this.

[tianyiswufeng]

Splitting this, because half already works.

Custom endpoint / local models: possible today per provider via Settings → provider → Environment variables. The Claude driver's recipe is in docs/user/providers-claude.md ("I Want To Use OpenRouter") — ANTHROPIC_BASE_URL, ANTHROPIC_AUTH_TOKEN, empty ANTHROPIC_API_KEY. Point it at any Anthropic-compatible server. Models are then selected by typing the custom slug into the picker search — see #4149 for why the built-in role-mapping vars don't apply to picker selections.

Your own harness: not configurable. Drivers are compiled in — apps/server/src/provider/Drivers/ has exactly Claude, Codex, Cursor, Grok and OpenCode — so a new harness is a new driver, not a config entry. The nearest escape hatch is the OpenCode lane with your own opencode.json, currently blocked by #4239.