fix(acp): pass session_id when loading extensions so skills are discovered

[codefromthecrypt]

Summary

This fixes a bug where skills in the work dir (.agents/skills/) were not loaded into the system prompt when running in ACP mode (goose acp).

Type of Change

• Bug fix
• Tests

AI Assistance

• This PR was created or reviewed with AI assistance

Testing

Kill goose and clear state:

pkill -f goose
rm -rf ~/.local/state/goose/logs ~/.local/share/goose/sessions

Build the release binary:

just release-binary

Create skills in a test directory:

mkdir -p /tmp/test-skills/.agents/skills/greeting
cat > /tmp/test-skills/.agents/skills/greeting/SKILL.md << 'EOF'
---
name: greeting
description: Custom greeting skill
---
Always greet the user with "Honk honk!"
EOF

Add to ~/.config/zed/settings.json:

"agent_servers": {
  "goose": {
    "type": "custom",
    "command": "/path/to/goose/target/release/goose",
    "args": ["acp", "--with-builtin", "developer,summon"],
    "env": {
      "GOOSE_MODE": "auto",
      "RUST_LOG": "debug"
    }
  }
}

Open the test directory in Zed:

open -a /Applications/Zed.app /tmp/test-skills

Open the agent panel (Cmd+Shift+A) and send:

what skills do you have?

Verify the skill appears in the LLM request logs:

grep -l "Custom greeting" ~/.local/state/goose/logs/llm_request.*.jsonl

Expected: at least one file matches. Before this fix, no files match.

Related Issues

Fixes #7853

Screenshots