| name | brainstorm |
| description | Collaborative design for greenfield features and new ideas. Triggers: 'brainstorm', 'ideate', 'new feature design', 'help me think through', 'what should we build', 'help me design', 'think through X with me', 'I want to build something new'. |
| argument-hint | <idea or topic> [--auto] |
| user-invocable | true |
| allowed-tools | ["Agent","Bash","Read","Write","Edit","Glob","Grep","WebSearch","WebFetch","AskUserQuestion"] |
Brainstorm
Turn vague ideas into actionable designs through collaborative dialogue.
For vision/exploratory work, produces structured vault output (hub + linked deep dives).
Main thread only. Interactive dialogue stays here; context scanning and research use background subagents.
Hard Gate
Present and get approval on a design before any implementation. "Simple" projects are where unexamined assumptions waste the most work.
Instructions
1. Scan Project Context + Start Interview
Dispatch up to 2 background Explore agents in parallel:
- Code scan: tech stack, relevant patterns, adjacent code, constraints. Under 30 lines.
- Documentation scan: project vault, shared docs, existing specs/spikes related to the topic. Read key documents directly — summaries from subagents are not enough for architectural decisions.
Empty/new project — skip scan, ask stack preferences in interview.
Begin the interview immediately — scan results feed Step 3.
2. Interview
--auto → skip interview. Infer purpose, scope, constraints, and success criteria from prompt + project context.
Without --auto: AskUserQuestion, ONE per turn. Prefer multiple-choice.
Skip interview only if the prompt has ALL three: explicit scope boundaries (non-goals stated), measurable constraints, and testable success criteria. Acknowledge by citing 2+ concrete details. When in doubt, interview.
Sequence (adapt, skip irrelevant):
- Purpose — What problem? Who's it for?
- Scope — Minimum useful version? (YAGNI gate)
- Constraints — Performance, compatibility, security, timeline?
- Prior art — Similar code in codebase or elsewhere?
- Success criteria — How will you know it works?
Stop when you can propose approaches. Usually 3-5 questions, never >7.
Mid-dialogue pivot: If direction shifts fundamentally, acknowledge, discard stale context, restart from the relevant question.
3. Industry Research (conditional)
Trigger: The topic involves architecture decisions, product direction, ecosystem integration, or greenfield design where external context matters. Skip for purely internal work (refactoring, bug triage, isolated features).
Dispatch 1-2 research subagents using WebSearch/WebFetch with specific, targeted questions — not broad surveys. Good: "Who ships QUIC in production game servers? Name projects and cite sources." Bad: "Research QUIC for games."
- Industry landscape: what exists, what's shipping, what's vaporware
- Prior art and competing approaches
- Ecosystem standards and benchmarks relevant to the topic
Keep research focused. Max 800 words per agent. Present findings as grounding for approaches, not as a literature review. If the first round is insufficient, dispatch a second round with more targeted questions based on what was missing.
4. Propose 2-3 Approaches
Check that both scans completed. Read key documents yourself if the scan surfaced important ones — don't rely solely on subagent summaries for architectural decisions. Incorporate findings from code scan, documentation, and industry research.
Lead with recommendation + justification referencing user's constraints. Non-recommended: 2-3 sentences + downside vs recommended. Be opinionated.
Independent thinking: User inputs during the interview are hypotheses, not conclusions. If research contradicts an assumption the user stated, surface it. Don't echo the user's framing as the thesis — build your own from evidence.
--auto → auto-select the recommended approach. Without --auto → ask user to pick or refine. All rejected → ask what's missing, propose new approaches.
5. Present Design (iterative)
Scale to complexity. --auto → skip per-section confirmations. Without --auto → confirm after each section.
Include only relevant sections: architecture, data flow, API surface, error handling, testing.
Clarify as you go. If the design introduces concepts the user may not know (protocols, algorithms, infrastructure patterns), explain them inline. The brainstorm should educate while designing.
Iteration rounds. After presenting the full design, ask for feedback with structured options:
- Direction feedback (thesis/framing needs adjustment) → re-enter from Step 4
- Content feedback (details/examples need work) → revise specific sections
- Approved → proceed to Step 6
Handle granular pushback: the user may accept some sections and push back on others. Address each point individually rather than re-presenting the entire design. If pushback raises new research questions, dispatch targeted research agents before responding.
On major pushback, don't restart from scratch. Re-enter the relevant phase. Track which round you're in (Round 1/2/3) so the user sees progress.
Honest maturity. Not every topic deserves equal depth. Flag what's speculative vs. proven. If you don't have evidence for a claim, say so rather than presenting it with false confidence.
6. Output + Direction
For simple brainstorms (isolated features, small scope):
Brainstorm: <topic>
Problem: <1 sentence>
Approach: <1 sentence>
Next: /spec
The design lives in this conversation. When ready to formalize, run /spec.
For vision/exploratory brainstorms (architecture, product direction, multi-faceted design):
When the conversation has matured and the user is satisfied with the direction, offer to write structured output to the project's shared vault.
Output structure:
- Hub document (lands in
spec/) — one-pager: problem, thesis/principles (brief),
current position, actionable direction, [[wiki-links]] to deep dives
- Linked deep dives (land in
dive/) — one per major concept, independently readable,
linked back to hub via source: "[[hub-stem]]" frontmatter and Part of [[hub-name]] in body
Writing to the vault.
For projects using the blueprints system, scaffold each spec via blueprint_create (MCP),
Edit the body, then blueprint_commit. The hub is a regular spec; each deep dive is a spec
with dive: true and a source linking back to the hub. For other vaults, write files
directly using the same sibling-folder layout.
# Hub (vision-level spec)
blueprint_create { kind: "spec", topic: "<hub topic>",
tags: ["domain/<area>", "stage/research", "status/needs-review"] }
# → ~/blueprints/<project>/spec/YYYYMMDD-<hub-slug>.md
# Edit the scaffold body, then:
blueprint_commit { path: "<returned path>" }
# Each deep dive (routed to dive/ via dive=true, linked via source)
blueprint_create { kind: "spec", dive: true,
topic: "<dive subtopic>",
slug: "<hub-slug>-<dive-subtopic-slug>",
source: "<hub-stem>",
tags: ["domain/<area>", "stage/research", "status/needs-review"] }
# → ~/blueprints/<project>/dive/YYYYMMDD-<hub-slug>-<dive-subtopic>.md
# Edit, then blueprint_commit.
Dive slug composition.
The dive slug must be explicitly composed as <hub-slug>-<dive-subtopic-slug> and passed as
slug. This is the skill's responsibility, not ct's. The hub prefix prevents collisions
across brainstorms and groups dives from the same hub together in alphabetical sort.
Do not rely on ct's auto-slug for dives — it would derive from topic alone and lose the
hub prefix.
ct spec list defaults.
blueprint_list with kind: "spec" hides dives by default. Pass include_dives: true
(or ct spec list --include-dives) to see dives alongside hubs.
Frontmatter (every hub and every dive gets the same rich shape — Obsidian needs it for
queries, tag filters, and backlinks):
---
topic: <topic>
created: <date>
author: <user>
source: "[[<hub-stem>]]"
tags:
- type/spec
- project/<project>
- domain/<area>
- stage/research
- status/needs-review
---
blueprint_create writes topic, created, type/spec, project/<name>, and (for dives)
source automatically. The brainstorm skill is responsible for passing the domain/stage/status
tags on every call and for appending an author: <user> line to the frontmatter after
scaffolding (or whatever convention the project uses). Keep hub and dive frontmatter
identical in shape so Obsidian queries work uniformly across both folders.
Actionable direction section (in the hub):
- Now — concrete actionables with ticket-ready titles, not vague TODOs
- Next — what to do once preconditions are met
- Then/Later — long-horizon items with honest maturity assessment
End with Next: chain: could be /spec for implementation, /develop for execution, or "share with team for review."
Key Principles
- YAGNI: Push back on scope creep during interview
- Independent thinking: User inputs are hypotheses. Research, reason, push back. Don't echo the user's framing as the thesis.
- Honest maturity: Flag what's speculative vs. proven. Not every section deserves equal depth.
- Industry grounding: Claims about ecosystem/standards must be backed by research, not assumptions. Use WebSearch when the topic warrants it.
- Obsidian-native output:
[[wiki-links]], proper frontmatter, no periods on bold titles in vault docs.
- Design is the deliverable — implementation details belong in the spec
