# Brainstorm Build Mid > Use when the user wants straight Opus quality for both the thinking and the code — an all-Opus plan then build, run autonomously with no stop in between, no Fable creative ideation, no Sonnet cost-tiering and no ceremony (no session record, no handoff checkpoint). For a Fable-led creative design plus the full ceremony use brainstorm-build-prime; to offload the simple / mechanical parts to Sonnet use brainstorm-build-lite. NOT for tiny one-line edits (just do them) or pure design/no-build work. - Skill: `bodish-coder/brainstorm-build-mid` (Agent Skill) - Install (CLI): `npx skillmds@latest add bodish-coder/brainstorm-build-mid` - Raw SKILL.md: https://api.skillmd.com/api/skills/bodish-coder/brainstorm-build-mid/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: bodish-coder (https://skillmd.com/u/bodish-coder) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/bodish-coder/brainstorm-build-mid --- # Plan (Opus 5) → Build (Opus 4.8) The Opus tier end to end: **Opus 5** does the design thinking, then **Opus 4.8** does the implementation. A skill can't change the main session's model, so each phase runs as an **Opus subagent** (`model: "opus"`). You (the main session) orchestrate only — spawn the agents, pass the design between them, relay the result. **Intended split: Opus 5 plans, Opus 4.8 builds** — the newer model for the design thinking, the proven coder for the implementation. > **Version note (honest limit):** on **Claude Code** this split is currently > *not expressible*. The Agent tool's `model` field takes tiers (`opus`, > `sonnet`, `haiku`, `fable`), not version slugs, so `opus` resolves to whatever > Opus the run is on and **both phases get the same one**. Say so once, then run > both on the session's Opus. To plan and build on a specific Opus today, run the > whole session on it. > > On hosts that *do* expose version slugs (Cursor, and any host whose model list > in `PLATFORMS.md` names versions), take the split: design on the Opus 5 slug, > build on the Opus 4.8 slug. Record both in the run's summary. ## Craft — read this first Read **`PRACTICE.md`** at the plugin root (beside `PLATFORMS.md`). It is skillator's process canon — the superpowers process skills merged in, in skillator's own words — so none of them is chained in front of this one: classify the request spike/bounded/architectural and say which out loud; one question at a time; the plan-grade TASKS shape a build agent can work from cold; design self-review; the test-first law; fresh-evidence verification; debugging (§7); branch lifecycle (§8). Everything below assumes it. ## Phase 1 — Opus plans Dispatch one subagent, `model: "opus"` (the Opus 5 slug where the host has one), `subagent_type: "general-purpose"`. Give it the user's task text and the repo context. Ask it to commit to an approach and **write** an implementation-ready design to a file, returning only that path plus a two-line summary: ``` CHOSEN: DESIGN: CONSTRAINTS: TASKS: VERIFICATION: ``` **The design file — minimal, not a session record.** Write it to the scratchpad (or `docs/sessions/` if the user wants it kept) as `design--.md`. It exists for one reason: `practice/task-loop.md` and every template in `practice/prompts.md` take a `` path (`taskwork.sh brief `), and a build agent that never saw this conversation reads the design from disk, not from a pasted prompt. That is the whole ceremony this tier keeps — no outcome section, no session narrative, no handoff-and-shed checkpoint. Confirm the path in your reply. ## Phase 2 — Opus builds Dispatch Opus subagent(s), `model: "opus"` (the Opus 4.8 slug where the host has one). Each gets the **design file path** and its own task block — never the design pasted into the prompt and never this session's history (PRACTICE.md §4; procedure in `practice/task-loop.md`, prompt text in `practice/prompts.md`). Build exactly the design, stay inside the declared files. Independent tasks can run in parallel (git worktree if they'd touch the same tree). If the design hits a real blocker only the user can resolve, stop and surface it — don't guess. ## Phase 3 — Verify & relay Run the VERIFICATION step (Opus agent or main session) through PRACTICE.md §5: identify the command, run it in full now, read the whole output and exit code, and only then claim — with the evidence attached. Never from an earlier run. On failure, fix it and re-run. Then relay concisely: the approach, what was built (files), and the verification result. ## Workflow mode — wide builds When the plan returns **4+ independent tasks**, or the work is a sweep (migration, audit, codemod), or the user asked for it, run Phases 1-3 as a **single deterministic workflow script** instead of hand-dispatched subagents: plan → one Opus build agent per task → verify each → loop the failures. Read **`WORKFLOW.md`** (beside the installed skills, or at the repo/plugin root) for the criteria, host table, and a ready script — use the same two model picks as Phases 1-2 in its design/build stages, and ignore its `complexity` tag. Write the design file before the call and pass its path in `args`, exactly as Phase 2 would. For 1-3 sequential tasks, stay with plain dispatch — a script buys nothing. ## Rules - **Both phases are Opus subagents.** Don't design or code in the main session. - **Pass the design by path, never by paste.** The design file carries the contracts and edge cases; a build agent reads it. Pasting it into the prompt parks the whole design in your context for the rest of the session (`practice/task-loop.md`, Context hygiene) and is not what the canon's templates take. - **Minimal ceremony, real canon.** This tier writes the design file and nothing else: no session record, no Outcome section, no rework loop, and no §6 whole-branch reviewer — that end-of-build `deep`-tier pass is prime's ceremony, and this tier seats no `deep` model. It ships on §5 evidence plus §4's per-task review. PRACTICE.md §§1-5, and §6's receiving-review discipline, still apply — that is what the design file makes possible. - **Autonomous but honest.** No confirmation gate; but if a phase fails or an agent returns nothing, say so plainly and stop rather than continuing on a missing piece. - **Handoff before any context loss.** This tier runs no `/compact` or `/clear` of its own, but if you or the user are about to run either, **first run the `handoff` skill** — never compact/clear without a verified handoff. - Want Fable's creative brainstorm + the full ceremony? Use brainstorm-build-prime. Want to offload simple/mechanical tasks to Sonnet? Use brainstorm-build-lite. ## Other hosts "Opus" and the Agent tool above are the **Claude Code** defaults. On Cursor, Codex, Antigravity, Pi, or Prime Agent, read `PLATFORMS.md` (beside the installed skills, or at the repo/plugin root) and use the host's **build tier** for both phases, with its own delegate mechanism. No delegation available → run plan then build **sequentially in one session**, writing the design to disk before building from it.