client-compatibility

## Context Squad runs on multiple Copilot surfaces (CLI, VS Code, JetBrains, GitHub.com). The coordinator must detect its platform and adapt spawning behavior accordingly. Different tools are available on different platforms, requiring conditional logic for agent spawning, SQL usage, and response timing. ## Patterns ### Platform Detection Before spawning agents, determine the platform by checking available tools: 1. **CLI mode** — `task` tool is available → full spawning control. Use `task` with `agent_type`, `mode`, `model`, `description`, `prompt` parameters. Collect results via `read_agent`. 2. **VS Code mode** — `runSubagent` or `agent` tool is available → conditional behavior. Use `runSubagent` with the task prompt. Drop `agent_type`, `mode`, and `model` parameters. Multiple subagents in one turn run concurrently (equivalent to background mode). Results return automatically — no `read_agent` needed. 3. **Fallback mode** — neither `task` nor `runSubagent`/`agent` available → work inline. Do not apologize or explain the limitation. Execute the task directly. If both `task` and `runSubagent` are available, prefer `task` (richer parameter surface). ### VS Code Spawn Adaptations When in VS Code mode, the coordinator changes behavior in these ways: - **Spawning tool:** Use `runSubagent` instead of `task`. The prompt is the only required parameter — pass the full agent prompt (charter, identity, task, hygiene, response order) exactly as you would on CLI. - **Parallel...