models.json cache corruption causes intermittent startup failure for config.providers and provider.list

[AlexPawlicki]

Bug

opencode fails to start intermittently with:

Error: 2 of 5 requests failed: Unexpected server error. Check server logs for details.
Affected startup requests: config.providers, provider.list

Root Cause (from server logs)

The actual error in the server log is:

ERROR service=server error=JSON Parse error: Unexpected EOF cause=SyntaxError: JSON Parse error: Unexpected EOF
    at ModelsDev.populate
    at Provider.list
    at ConfigHttpApi.providers

~/.cache/opencode/models.json gets corrupted (truncated/empty) if opencode is terminated while writing an updated model catalog to that file. On the next launch, ModelsDev.populate fails to parse the truncated JSON, which causes both config.providers and provider.list to fail, producing the "Unexpected server error" shown to the user.

Steps to Reproduce

1. While opencode is running, hard-kill the process (e.g. close terminal, kill PID, machine sleep/wake) during a model catalog refresh
2. Re-launch opencode — it fails with the error above

Expected Behaviour

opencode should handle a corrupted/missing models.json gracefully by re-downloading the model catalog rather than failing startup.

Suggested Fix

Write the updated catalog to a temp file and atomically rename it to models.json, so a mid-write kill cannot leave a partially-written file. Also add a fallback: if readJson throws a parse error on the cache file, delete it and re-fetch rather than propagating the error up to the startup requests.

Environment

• Platform: Windows 11 (win32)
• Shell: PowerShell 5.1
• opencode: 1.15.13

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• return {} on json parse error #29366: Same root cause — JSON parse failure in models.json (via models-dev.ts) causing startup failure, with a similar fix suggestion (handle parse errors gracefully rather than propagating them)
• Error: 4 of 5 requests failed: config.providers: Unexpected server error. #27530: Same user-visible error (config.providers/provider.list startup failure with "Unexpected server error"), though that issue doesn't identify the models.json corruption as the cause