[BUG] Plugin fails with confusing errors if started with the other oauth plugin's cache files

[riatzukiza]

Bug Description
i seem to be getting this error again in the plugin logs: ERROR 2025-11-19T20:09:23 +1ms service=openai-codex-plugin error=Failed to fetch OpenCode codex.txt: 404 Failed to fetch OpenCode codex.txt from GitHub
[2:12 PM]shuv: this might be bits left over from the other plugin actually
[2:13 PM]shuv: https://github.com/sst/opencode/blob/dev/.opencode/opencode.jsonc
[2:14 PM]shuv: the other codex auth plugin keeps installing whenever i dev against the opencode repo, because they have that .opencode folder with a config file adding "plugin": ["opencode-openai-codex-auth"]
Steps to Reproduce
0. clear all opencode caches ~/.opencode,.cache/opencode

1. add "plugin": ["opencode-openai-codex-auth"] to your opencode.json
2. start opencode session, do some work with codex
3. close opencode
4. change opencode.json plugin entry to "plugin":["@openhax/codex"]
5. start opencode

Expected Behavior
User can use codex, but better

Actual Behavior
User get's an error preventing them from using the plugin

Environment

• opencode version: 1.0.78
• Plugin version: 0.0.1
• Operating System: Mac
• Node.js version:

Logs
If applicable, attach logs from ~/.opencode/logs/codex-plugin/ (enable with ENABLE_PLUGIN_REQUEST_LOGGING=1)

Compliance Checklist
Please confirm:

• I'm using this plugin for personal development only
• I have an active ChatGPT Plus/Pro subscription
• This issue is not related to attempting commercial use or TOS violations
• I've reviewed the FAQ and Troubleshooting sections

Additional Context
Add any other relevant information.

[riatzukiza]

✅ RESOLVED: Cache Isolation Implementation

Root Cause: Both opencode-openai-codex-auth and @openhax/codex plugins used identical cache file names in ~/.opencode/cache/, causing conflicts when switching between plugins.

Solution Implemented:

1. Cache Isolation (lib/utils/cache-config.ts):

   • Added PLUGIN_PREFIX = "openhax-codex" for unique cache namespace
   • Updated cache files to use plugin-specific prefixes:
     • openhax-codex-instructions.md (was codex-instructions.md)
     • openhax-codex-opencode-prompt.txt (was opencode-codex.txt)
     • Corresponding metadata files with -meta.json suffix

2. Migration Logic (lib/prompts/opencode-codex.ts):

   • migrateLegacyCache(): Automatically detects and migrates old cache files
   • validateCacheFormat(): Detects incompatible cache formats from other plugins
   • Enhanced error messages with actionable guidance for cache conflicts

3. Test Updates:

   • Updated all test files to use new cache file names
   • All 123 tests passing ✅

User Experience:

• Seamless migration: Users switching plugins get automatic cache migration
• Clear error messages: When cache conflicts occur, users get actionable guidance
• No data loss: Existing cache content is preserved during migration

Files Modified:

• lib/utils/cache-config.ts - Cache isolation configuration
• lib/prompts/opencode-codex.ts - Migration and validation logic
• test/prompts-opencode-codex.test.ts - Updated cache file paths
• test/prompts-codex.test.ts - Updated cache file paths

Users can now switch between plugins without cache conflicts or data loss.