opencode-anthropic-oauth-patch

Installable OpenCode plugin that restores Anthropic provider visibility, reads the working OpenCode OAuth token file, refreshes Anthropic access tokens, and patches Claude request shape for OpenCode/oh-my-opencode.

This is meant for OpenCode/oh-my-opencode-style integrations where Claude OAuth requests break because extra Anthropic-incompatible fields are injected into the request path.

What it patches automatically as an OpenCode plugin

• Registers an Anthropic auth/provider bridge for OpenCode using ~/.local/share/opencode/auth.json
• Refreshes Anthropic OAuth access tokens through https://console.anthropic.com/v1/oauth/token
• Removes thinking, output_config, and related Anthropic-problematic option fields from OpenCode provider options
• Rewrites OpenCode system prompt strings into a single Claude-Code-compatible system string
• Sets Claude-Code-compatible Anthropic headers by default
• Installs a targeted global fetch patch that sanitizes outbound Anthropic OAuth message bodies, including final system[*].cache_control removal

How the automatic patch works

The root plugin uses two layers:

1. OpenCode hooks (chat.params, chat.headers, experimental.chat.system.transform) for public-ABI-safe fixes
2. a narrowly targeted globalThis.fetch wrapper that only patches https://api.anthropic.com/v1/messages... requests carrying Authorization: Bearer ...

That second layer is what makes the package automatic for the cache_control problem too.

Install

Add the package to your opencode.json plugin list:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": [
    "@suncreation/opencode-claude-patch"
  ]
}

Install it from this repository:

npm install /Users/admin/Projects/npm/opencode-anthropic-oauth-patch

If you later publish it, keep the same plugin entry and install with:

npm install @suncreation/opencode-claude-patch

One-line npx installer

To both download the package and register it in your OpenCode plugin config automatically:

npx -y @suncreation/opencode-claude-patch install

This command now does both:

• installs the package into OpenCode's runtime cache
• adds the plugin entry to ~/.config/opencode/opencode.json

Useful variants:

npx -y @suncreation/opencode-claude-patch status
npx -y @suncreation/opencode-claude-patch remove
npx -y @suncreation/opencode-claude-patch install --config ~/.config/opencode/opencode.json
npx -y @suncreation/opencode-claude-patch install --runtime ~/.cache/opencode --version latest

Anthropic login commands

The package can also manage Anthropic OAuth credentials directly in ~/.local/share/opencode/auth.json.

npx -y @suncreation/opencode-claude-patch login
npx -y @suncreation/opencode-claude-patch status
npx -y @suncreation/opencode-claude-patch refresh
npx -y @suncreation/opencode-claude-patch logout

Useful login options:

npx -y @suncreation/opencode-claude-patch login --mode max
npx -y @suncreation/opencode-claude-patch login --mode console
npx -y @suncreation/opencode-claude-patch login --no-open
npx -y @suncreation/opencode-claude-patch login --code '<code#state>'
npx -y @suncreation/opencode-claude-patch status --auth-path ~/.local/share/opencode/auth.json

OpenCode will auto-install npm plugins referenced in opencode.json at startup.

What the root package export does

The root package export is an OpenCode plugin function. Once installed and listed in opencode.json, it auto-applies:

• Anthropic auth/provider loading backed by the OpenCode OAuth token file
• chat.params patching for Anthropic/Claude models
• chat.headers patching for Claude-compatible headers
• experimental.chat.system.transform patching for a single Claude-Code-style system prompt
• a targeted globalThis.fetch patch for final Anthropic OAuth request-body cleanup

No extra wiring is needed.

Optional environment toggles

OPENCODE_ANTHROPIC_OAUTH_SET_HEADERS=0
OPENCODE_ANTHROPIC_OAUTH_SYSTEM_PREFIX="You are Claude Code, Anthropic's official CLI for Claude."

Helper subpath for lower-level integrations

import {
  createAnthropicOAuthPatchedFetch,
  mergePatchHeaders,
  normalizeAnthropicSystemStrings,
  sanitizeAnthropicOptions
} from "@suncreation/opencode-claude-patch/helpers";

// if published:
// import { ... } from "@suncreation/opencode-anthropic-oauth-patch/helpers";

const options = sanitizeAnthropicOptions({
  thinking: { type: "adaptive" },
  output_config: { effort: "max" }
});

const headers = mergePatchHeaders({});
const system = normalizeAnthropicSystemStrings([
  "Be concise.",
  "Answer in Korean."
]);

const patchedFetch = createAnthropicOAuthPatchedFetch(fetch, {
  ensureClaudeCodeSystem: true,
  normalizeSystemToUserMessage: true
});

console.log(options, headers, system, typeof patchedFetch);

Notes

• The root export is safe for opencode.json -> plugin installation.
• The ./helpers subpath is for deeper interceptors or forks.
• It does not mint OAuth tokens or bypass account-level/provider policy restrictions.
• This package is targeted at Claude OAuth / oh-my-opencode-style setups. If you use Anthropic API keys and want native reasoning features, do not enable it globally.