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)

1e. Active Context Compaction Gate

After Step 1d completes and brainstorm-summary.md is written, enter the active compaction gate before creating the Design Doc. At this point the OpenSpec handoff, brainstorming decisions, and pending items are durable, so the agent should proactively release the earlier Spec and brainstorming context to preserve window space for Step 2 and the later Build phase.

Rules:

• If the current platform provides a native context compaction/cleanup mechanism (for example, the host agent's compact/compaction command, tool, or UI action), trigger active compaction here once; do not try to fake compaction through a shell script.
• The compaction resume prompt must include the change name, current step (Design Step 2), and the three handoff file categories listed above.
• If the current platform cannot be compacted programmatically by the agent, pause and tell the user to run the host platform's manual compaction action; continue to Step 2 only after the user confirms compaction is unavailable or asks to continue.

2. Create Design Doc

Create the Design Doc based on the full brainstorming conversation context (still in the main session).

Design Doc frontmatter must be minimal:

---
comet_change: <change-name>
role: technical-design
canonical_spec: openspec
---

Write the Design Doc to docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md. If Spec Patches need to be written back, also edit the corresponding specs/*/spec.md.

Context compaction recovery: If context has been compacted, resume from brainstorm-summary.md + handoff context. If the user has not confirmed the design proposal yet, return to Step 1b/1c and continue brainstorming; if the user has confirmed it, continue creating the Design Doc. brainstorm-summary.md is the compaction checkpoint, not the sole input for the Design Doc — when creating, leverage the full recovered context as much as possible.

3. Update Comet State

First record the design_doc path. If Spec Patches wrote back delta spec (added or modified specs/*/spec.md), must regenerate handoff to update hash:

# Record design_doc path
"$COMET_BASH" "$COMET_STATE" set <name> design_doc docs/superpowers/specs/YYYY-MM-DD-topic-design.md

# If delta spec changes exist, regenerate handoff (update hash)
"$COMET_BASH" "$COMET_HANDOFF" <change-name> design --write

# Auto-transition to next phase
"$COMET_BASH" "$COMET_GUARD" <change-name> design --apply

If there are no delta spec changes, skip the handoff regeneration step. The state file updates automatically; no manual editing of other fields needed.

Exit Conditions

• Design Doc created and saved
• Design Doc frontmatter contains comet_change, role: technical-design, canonical_spec: openspec
• handoff_context and handoff_hash written to .comet.yaml (enforced by guard)
• handoff_hash matches current OpenSpec open phase artifacts (enforced by guard)
• design-context.md or beta spec-context.md must be script-generated and contain source path, mode, sha256 traceability markers (enforced by guard)
• In beta mode, spec-context.json must be structurally valid and reference the current source files (enforced by guard)
• If new capabilities or supplementary acceptance scenarios exist, OpenSpec delta spec has been created/updated
• design_doc written to .comet.yaml
• Phase guard: Run "$COMET_BASH" "$COMET_GUARD" <change-name> design --apply; after all PASS, auto-transitions to phase: build

Must use --apply before exit:

"$COMET_BASH" "$COMET_GUARD" <change-name> design --apply

Context Compression Recovery

Follow comet/reference/context-recovery.md with phase set to design.

Automatic Handoff to Next Phase

Follow comet/reference/auto-transition.md. Key command:

"$COMET_BASH" "$COMET_STATE" next <change-name>

• NEXT: auto → invoke the skill pointed to by SKILL to enter the next phase
• NEXT: manual → do not invoke the next skill; prompt user to run /<SKILL> manually
• NEXT: done → workflow is complete, no further action needed