Comet Design

Comet Phase 2: Deep Design (Design)

Prerequisites

• Active change exists (proposal.md, design.md, tasks.md)
• No Design Doc (no corresponding file under docs/superpowers/specs/)

Steps

0. Entry State Verification (Entry Check)

Execute entry verification:

COMET_ENV="${COMET_ENV:-$(find . "$HOME"/.*/skills "$HOME/.config" "$HOME/.gemini" -path '*/comet/scripts/comet-env.sh' -type f -print -quit 2>/dev/null)}"
if [ -z "$COMET_ENV" ]; then
  echo "ERROR: comet-env.sh not found. Ensure the comet skill is installed." >&2
  return 1
fi
. "$COMET_ENV"
"$COMET_BASH" "$COMET_STATE" check <name> design

Proceed to Step 1 after verification passes. The script outputs specific failure reasons when verification fails.

Idempotency: All design phase operations can be safely re-executed. If handoff_context and handoff_hash already exist, confirm they match current artifacts before deciding whether to regenerate.

1a. Generate OpenSpec → Superpowers Handoff Package

Must be generated by script. Agent writing summaries on the fly is not allowed.

"$COMET_BASH" "$COMET_HANDOFF" <change-name> design --write

The script reads the change .comet.yaml context_compression snapshot, then generates and records the matching handoff package.

Default context_compression: off generates:

openspec/changes/<name>/.comet/handoff/design-context.json
openspec/changes/<name>/.comet/handoff/design-context.md

Beta mode (context_compression: beta in project .comet/config.yaml, snapshotted into .comet.yaml when the change is created) generates:

openspec/changes/<name>/.comet/handoff/spec-context.json
openspec/changes/<name>/.comet/handoff/spec-context.md

And writes to .comet.yaml:

handoff_context: openspec/changes/<name>/.comet/handoff/design-context.json
handoff_hash: <sha256>

The default handoff package is a compact traceable excerpt, not an agent summary:

• design-context.json: machine index containing change, phase, canonical spec, source paths, hash
• design-context.md: context for Superpowers to read, containing script markers, source path, line range, sha256, deterministic excerpts
• When exceeding excerpt budget, marks [TRUNCATED] and retains Full source path

The beta handoff package is a structured spec projection that reduces OpenSpec token load without replacing the canonical spec:

• spec-context.json: machine index containing change, phase, canonical spec, source paths, hash, and file roles
• spec-context.md: context for Superpowers to read, verbatim-projecting delta spec files and referencing supporting artifacts by hash
• OpenSpec delta specs remain canonical; if the projection is missing, stale, or unclear, regenerate the handoff or read the source spec directly instead of writing an agent summary

If full context is genuinely needed, explicitly run:

"$COMET_BASH" "$COMET_HANDOFF" <change-name> design --write --full

Handoff package sources come from OpenSpec open phase artifacts:

• proposal.md: goals, motivation, scope, non-goals
• design.md: high-level architecture decisions, approach constraints
• tasks.md: initial task boundaries
• specs/*/spec.md: delta capability specs

1b. Execute Brainstorming (with Context)

Immediately execute: Use the Skill tool to load the Superpowers brainstorming skill. Skipping this step is prohibited.

When loading the skill, ARGUMENTS must include:

Language: Use the language of the user request that triggered this workflow

After the skill loads, follow its guidance and use the following context:

Change: <change-name>
OpenSpec Context Pack: openspec/changes/<name>/.comet/handoff/design-context.md
Machine handoff: openspec/changes/<name>/.comet/handoff/design-context.json

If context_compression is beta, use:
OpenSpec Context Pack: openspec/changes/<name>/.comet/handoff/spec-context.md
Machine handoff: openspec/changes/<name>/.comet/handoff/spec-context.json

OpenSpec artifacts are the upstream source of truth, but you must not weaken the Superpowers `brainstorming` clarification flow by "skipping redundant context exploration".
Your task is to perform deep technical design based on the handoff package: implementation approach, technical risks, testing strategy, boundary conditions.
If goals, scope, non-goals, acceptance scenarios, or key constraints remain unclear, you must continue asking questions and form the design proposal first; must not create the Design Doc after only one Q&A turn.
Do not rewrite proposal/spec; if you find OpenSpec delta spec missing acceptance scenarios, you may only propose Spec Patches and write them back to OpenSpec delta spec; do not create a second requirements spec in the Design Doc. Spec Patches are limited to supplementing acceptance scenarios, correcting ambiguous descriptions, or adding boundary conditions — they must not substantially rewrite the delta spec's structure or scope. If major changes are needed, flag them as design findings and return to brainstorming for confirmation.

Design Doc frontmatter must be minimal, containing only:
---
comet_change: <change-name>
role: technical-design
canonical_spec: openspec
---

Proceed through the original `brainstorming` skill flow: clarifying questions, 2-3 approaches, and step-by-step design confirmation. Do not write the Design Doc early.

Proceeding without loading this skill is prohibited.

If the Superpowers brainstorming skill is unavailable, stop the process and prompt to install or enable Superpowers skills. Do not substitute this step with normal conversation.

After the skill loads, follow its guidance to produce design proposals (presented as conversation):

• Technical approach: architecture, data flow, key technology choices and risks
• Testing strategy
• Requirement/scope gaps and Spec Patches to be written back
• If acceptance scenarios need supplementing, indicate delta spec changes to be written back

The brainstorming phase does not write to the Design Doc file; it only produces design proposals for Step 1c user confirmation. Only after confirmation should docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md be created and delta spec written back.

For context compaction recovery, the agent must incrementally update brainstorm-summary.md during brainstorming. After each clarification round or proposal iteration, update the file whenever new confirmed facts, key constraints, candidate approaches, trade-offs/risks, testing strategy, or Spec Patch candidates emerge; mark unconfirmed items as "pending" or "candidate". This file is a recovery checkpoint, not the Design Doc, and must not replace the Step 1c user confirmation.

1c. User Confirms Design Proposal (Blocking Point)

After brainstorming produces a design proposal, must follow the comet/reference/decision-point.md protocol to pause and wait for the user to explicitly confirm the design proposal. Must not create the final Design Doc, write design_doc, run design guard, or enter /comet-build before user confirmation.

When pausing, only present essential summary:

• Technical approach adopted
• Key trade-offs and risks
• Testing strategy
• If there are Spec Patches, list the delta spec changes to be written back

Only after the user explicitly confirms, proceed to Step 2. If the user requests adjustments, continue brainstorming iteration until the user confirms.

1d. Brainstorming Checkpoint Finalization

After the user confirms the design proposal, before creating the Design Doc, create or update the incrementally maintained checkpoint file and finalize it as the confirmed design summary:

mkdir -p openspec/changes/<name>/.comet/handoff

openspec/changes/<name>/.comet/handoff/brainstorm-summary.md structure:

# Brainstorm Summary

- Change: <change-name>
- Date: <YYYY-MM-DD>

## Confirmed Technical Approach

<summary of the user-confirmed approach>

## Key Trade-offs and Risks

<major trade-offs and risks>

## Testing Strategy

<testing method overview>

## Spec Patches

<delta spec changes to write back, or "None" if none>

Context compaction note: Each incremental update to brainstorm-summary.md is a relatively safe recovery point. After brainstorming completes, if the context window is tight, prefer compacting here. After compaction, reload the following files to continue Step 2:

• openspec/changes/<name>/.comet/handoff/brainstorm-summary.md
• openspec/changes/<name>/.comet/handoff/design-context.md (or spec-context.md in beta mode)
• openspec/changes/<name>/.comet/handoff/design-context.json (or spec-context.json in beta mode)