fix: minimal system prompt sanitization

[remorses]

Fixes the plugin by only replacing the specific OpenCode identity string instead of broader replacements that were causing Anthropic to block requests.

Also adds AGENTS.md with plugin testing instructions.

Fixes #33, fixes #32, fixes #12

[Copilot]

Pull request overview

This PR fixes critical authentication issues (issues #33, #32, #12) where Anthropic began blocking requests with "credential only authorized for Claude Code" errors. The fix changes the system prompt sanitization from broad regex replacements to a minimal, targeted string replacement to avoid detection.

Changes:

• Replaced broad regex replacements (/OpenCode/g, /opencode/gi) with a single specific string replacement to minimize detection surface
• Bumped version from 0.0.13 to 0.0.14
• Added AGENTS.md documentation with plugin testing instructions

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
package.json	Version bump to 0.0.14
index.mjs	Changed system prompt sanitization from broad regex to targeted string replacement
AGENTS.md	New documentation file with testing instructions and feature list

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[ErcinDedeoglu]

before merge: #33 (comment)

[coleleavitt]

have you tested this? I just tried this and this doesn't patch the issue. This PR is a moot

[remorses]

Did you follow instructions in AGENTS.md? @coleleavitt

[coleleavitt]

Did you follow instructions in AGENTS.md? @coleleavitt

I found the proper fix to this. I got a custom fork with a variety of features in addition to the upstream version

[Arasple]

This works.
They're no longer blocking "OpenCode" directly. Instead, they block "You are Claude Code, the best coding agent on the planet." pattern. (#33 (comment))

Since the "You are Claude Code, Anthropic's official CLI for Claude." spoof is automatically injected by OpenCode itself, the simpler solution is to do nothing.

[kuzaxak]

Did you follow instructions in AGENTS.md? @coleleavitt

Followed the guide, got error.

bun install v1.3.2 (b131639c)

+ @opencode-ai/plugin@0.4.45
+ @openauthjs/openauth@0.4.3

OPENCODE_DISABLE_DEFAULT_PLUGINS=true opencode run --model anthropic/claude-opus-4-5 hi
Error: This credential is only authorized for use with Claude Code and cannot be used for other API requests.