docs: prefer mm-worktree-task for subagent coding tasks in planner-backed projects

Claude-Session: https://claude.ai/code/session_015nXvGNNNixJPFwZKZHNyha

CLAUDE.md

@@ -67,6 +67,10 @@ Then proceed directly to step 2. Otherwise:
 
 When working with Gitea (watching Actions runs, checking whether a release/container built, diagnosing failing CI), use `gitea-agent-companion` — alias `gac`, installed in `~/sbin`, source at `projects/gitea-agent-companion`. Run `gitea-agent-companion --help` first: the help text is the full reference (verbs, flags, token discovery, exit codes). Canonical post-push pattern: `gac tail <owner/repo> --until run-complete --timeout 600`; on failure, `gac inspect <owner/repo> --run <N> --logs`.
 
+## Subagent coding tasks — use `mm-worktree-task`
+
+For any coding task delegated to a subagent in a project that has a planner (a `cp-cli planner` reference in its CLAUDE.md), strongly prefer `mm-worktree-task <item-uuid>` over hand-written subagent briefs or `/ask-minimax`. It fetches the work item, its documents, parent and siblings from the planner, prepends the standard implementation preamble, runs MiniMax M3 (1M context) detached in its own git worktree and branch, and can attach the report back to the item (`--collect --upload`). Source and spec: `projects/small-scripts` (`scripts/mm-worktree-task`, `specs/mm-worktree-task.spec.md`); pattern and gotchas: `projects/agent-runtimes/memory/gotchas-minimax.md`. The supervising session still owns review: run the full suite on the merged tree, and check any wire-shape change against the live server model before merging. Fall back to a Claude subagent only when the task has no work item or needs tools MiniMax cannot use.
+
 ## Process Principles
 
 Hard-won lessons that apply across every project: