Bug: --spec/--file flags crash opencode sessions on large prompts #98

What happened

When using agentctl launch opencode --spec <file> --file <file1> --file <file2>, the opencode process launches but dies silently within seconds. PID shows as dead almost immediately. No error output.

This happens when the combined content of spec + files is large (~50KB+). The content gets inlined into the shell command arguments, likely exceeding argv limits or causing opencode to choke on the escaped content.

What was expected

The session should start and the agent should have access to the file contents.

How to reproduce

# These files total ~44KB
agentctl launch opencode --cwd ~/code/mono-sandbox-archive-hardpin \
  --spec docs/artifacts/2026-02/sandbox-archive-node-affinity/SPEC.md \
  --file packages/sandbox-k8s/src/archive.ts \
  --file backend/task-worker-ts/src/core/brain/workflows/sandbox-lifecycle-sweeper.ts \
  -p "Make changes to these files"

# Check PID — dies within 5 seconds
sleep 5 && ps -p <pid>  # DEAD

Workaround: omit --spec/--file, let the agent read files from the worktree itself.

Suggested fix

Write spec/file contents to a temp file and pass the path to opencode, rather than inlining into argv. Or use stdin/pipe.

Environment

agentctl from npm link (local build), opencode 1.2.11 (Homebrew), macOS arm64