SystemPrompt.environment

Description

Bug: opencode run and TUI both crash with "Unexpected server error" on every prompt — SystemPrompt.environment throws TypeError: undefined is not an object (evaluating 'a.name')

Summary

Every single prompt attempt fails immediately with a generic UnknownError / "Unexpected server error" wrapper. The actual underlying crash (visible in the debug log) happens inside SystemPrompt.environment, before any request reaches the model provider. This reproduces on a completely clean $HOME and working directory, across multiple models, and in both run and the interactive TUI — so it is not caused by user config, agents, skills, or project files.

Environment

• OpenCode version: 1.18.30
• OS: Linux (Ubuntu-based, conda env)
• Providers tested: OpenCode Zen — mimo-v2.5-free, big-pickle
• Auth: fresh login via opencode auth login, valid key confirmed in auth.json

Error shown to user

Error: {
  "name": "UnknownError",
  "data": {
    "message": "Unexpected server error. Check server logs for details.",
    "ref": "err_<unique>"
  }
}

Actual error from debug log

TypeError: undefined is not an object (evaluating 'a.name')
    at resolve (/$bunfs/root/chunk-13bwg24f.js:2:1659)
    at a (/$bunfs/root/chunk-13bwg24f.js:2:936)
    at map (native:1:11)
    at <anonymous> (/$bunfs/root/chunk-13bwg24f.js:2:1626)
    at a (/$bunfs/root/chunk-13bwg24f.js:2:1166)
    at map (native:1:11)
    at <anonymous> (/$bunfs/root/chunk-13bwg24f.js:2:1626)
    at a (/$bunfs/root/chunk-13bwg24f.js:2:1166)
    at map (native:1:11)
    at <anonymous> (/$bunfs/root/chunk-13bwg24f.js:2:1390)
    at SystemPrompt.environment (/$bunfs/root/chunk-f0kkasg7.js:50:13096)
    at SystemPrompt.environment (definition) (/$bunfs/root/chunk-f0kkasg7.js:4:14254)
    at SessionPrompt.run (/$bunfs/root/chunk-f0kkasg7.js:50:14576)
    at SessionPrompt.run (definition) (/$bunfs/root/chunk-f0kkasg7.js:50:10099)
    at SessionRunState.ensureRunning (/$bunfs/root/chunk-f0kkasg7.js:50:14545)
    at SessionRunState.ensureRunning (definition) (/$bunfs/root/chunk-f0kkasg7.js:2:6720)
    at SessionPrompt.loop (/$bunfs/root/chunk-f0kkasg7.js:50:9849)
    at SessionPrompt.loop (definition) (/$bunfs/root/chunk-f0kkasg7.js:50:14481)
    at SessionPrompt.prompt (/$bunfs/root/chunk-tdg6vc0f.js:6:11695)
    at SessionPrompt.prompt (definition) (/$bunfs/root/chunk-f0kkasg7.js:50:9462)

The crash occurs on a nested .map() chain (three levels deep) inside SystemPrompt.environment, consuming an entry that is missing a .name field.

Steps to reproduce

opencode --pure run --model opencode/big-pickle "Reply with exactly: OK"

Fails every time, with a new ref each run, identical stack trace.

Isolation steps already performed (all still reproduce the crash)

1. Removed all custom opencode.json / opencode.jsonc files (previously contained a stale llama.cpp local provider — removing this did NOT fix it).
2. Removed AGENT.md / custom instructions from ~/.config/opencode/.
3. Ran with OPENCODE_DISABLE_EXTERNAL_SKILLS=1 — no change.
4. Ran with a completely empty $HOME:

   HOME=/tmp/opencode-clean-home opencode --pure run --model opencode/big-pickle "Reply with exactly: OK"
   

   — still crashes identically.
5. Ran with both a clean $HOME and a clean working directory (no git repo, no .opencode/, no project files):

   mkdir -p /tmp/opencode-clean-home /tmp/opencode-clean-cwd
   cd /tmp/opencode-clean-cwd
   HOME=/tmp/opencode-clean-home opencode --pure run --model opencode/big-pickle "Reply with exactly: OK"
   

   — still crashes identically.
6. Tested in the interactive TUI (not just run) — same "Failed to send prompt / Unexpected server error" message.
7. Tested two different models (mimo-v2.5-free, big-pickle) — same crash both times.
8. Confirmed via raw curl that the API/auth layer itself is reachable and functioning (separate MissingSessionID response confirmed for direct curl without a client-managed session, as expected) — so this is not an auth or network issue.

Expected behavior

opencode run "<prompt>" should successfully build the system prompt and return a model response, as it presumably does for most users on this version.

Suspected root cause

Per the public source (packages/opencode/src/session/system.ts, SystemPrompt.environment), this function assembles environment context including skill, reference, and MCP guidance. Since the crash reproduces with zero project files, zero custom skills, zero custom agents, and a totally empty $HOME, the malformed entry causing the missing .name is most likely coming from a built-in/bundled list (e.g. default skills, default MCP guidance, or default project-reference handling) rather than anything user-supplied.

Additional log context

A second, unrelated error also appears in the same run for the background session-title generation step (uses gpt-5.4-nano), reporting "No payment method" — this is a separate, expected billing-related issue on a sub-feature and not connected to the main crash, included here only for completeness:

error.error="AI_APICallError: No payment method. Add a payment method here: https://opencode.ai/workspace/.../billing"

Impact

This makes opencode completely unusable for any prompt, on any model, from any directory, on this version — a 100% reproduction rate, not an edge case.

Plugins

No response

OpenCode version

1.18.30

Steps to reproduce

No response

Screenshot and/or share link

Operating System

Ubuntu 26

Terminal

Terminal