docs: add Ox Alpha on OpenCode guide

docs: add Ox Alpha on OpenCode guide

Document how to reach the Ox Alpha preview through OpenCode Zen
(unauthenticated, model ID `x-preview-f-free`) and OpenCode Go
(authenticated, model ID `ox-alpha-free`). Include the `public`
API key marker behavior and verification results.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

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1 file changed, +92 -0

1	+	`# Ox Alpha on OpenCode`
2	+
3	+	`Date: 2026-08-25`
4	+
5	+	`Status: Measured`
6	+
7	+	`You can reach the Ox Alpha model through OpenCode on two different endpoints:`
8	+	`OpenCode Zen and OpenCode Go. The Zen version is unauthenticated and free.`
9	+	`The Go version requires an OpenCode Go API key.`
10	+
11	+	`## OpenCode Zen (unauthenticated)`
12	+
13	+	`OpenCode serves a free preview of Ox Alpha through its Zen gateway. You do not`
14	+	`need an account or an API key.`
15	+
16	+	The model ID is `x-preview-f-free` and the endpoint is:
17	+
18	+	```
19	+	`POST https://opencode.ai/zen/v1/chat/completions`
20	+	```
21	+
22	+	`Example request:`
23	+
24	+	```sh
25	+	`curl -s -X POST https://opencode.ai/zen/v1/chat/completions \`
26	+	`-H 'Content-Type: application/json' \`
27	+	`-d '{`
28	+	`"model": "x-preview-f-free",`
29	+	`"messages": [`
30	+	`{"role": "user", "content": "hi"}`
31	+	`],`
32	+	`"stream": false`
33	+	`}'`
34	+	```
35	+
36	+	The public models list at `https://opencode.ai/zen/v1/models` also includes
37	+	`x-preview-f-free`. A measured response returned `cost: "0"`, so this is the
38	+	`cheapest way to try Ox Alpha when it is available.`
39	+
40	+	`Note that the model is a limited-time free preview. It is rate-limited by source`
41	+	`IP and may become unavailable or change identifiers without notice.`
42	+
43	+	`## OpenCode Go (authenticated)`
44	+
45	+	The same model is also listed in OpenCode Go as `ox-alpha-free`. This version
46	+	`requires an OpenCode Go subscription and a workspace API key.`
47	+
48	+	The model ID is `ox-alpha-free` and the endpoint is:
49	+
50	+	```
51	+	`POST https://opencode.ai/zen/go/v1/chat/completions`
52	+	```
53	+
54	+	`Example request:`
55	+
56	+	```sh
57	+	`curl -s -X POST https://opencode.ai/zen/go/v1/chat/completions \`
58	+	`-H 'Content-Type: application/json' \`
59	+	`-H 'Authorization: Bearer $OPENCODE_GO_API_KEY' \`
60	+	`-d '{`
61	+	`"model": "ox-alpha-free",`
62	+	`"messages": [`
63	+	`{"role": "user", "content": "hi"}`
64	+	`],`
65	+	`"stream": false`
66	+	`}'`
67	+	```
68	+
69	+	The Go gateway parses the `Authorization` header as a `Bearer` token and looks
70	+	`up the key in the OpenCode console database. A missing, invalid, or exhausted`
71	+	key returns `401`.
72	+
73	+	## The `public` API key marker
74	+
75	+	The OpenCode CLI provider in `packages/opencode/src/provider/provider.ts` sets
76	+	`apiKey: "public"` when it does not find a stored credential. This is not a real
77	+	key. The OpenCode gateway explicitly ignores the string `public` and treats the
78	+	`request as unauthenticated. If the model does not allow anonymous access, the`
79	+	gateway returns `401 Missing API key`.
80	+
81	+	`## Verification`
82	+
83	+	`The measurements in this document were made on 2026-08-25:`
84	+
85	+	- `GET https://opencode.ai/zen/v1/models` returned `x-preview-f-free` without
86	+	`authentication.`
87	+	- `POST https://opencode.ai/zen/v1/chat/completions` with `x-preview-f-free`
88	+	returned a `200` completion with `cost: "0"` and no `Authorization` header.
89	+	- `POST https://opencode.ai/zen/go/v1/chat/completions` with `ox-alpha-free`
90	+	returned `401 Missing API key`.
91	+
92	+	`Recheck the live endpoints before relying on these values in production.`

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