Spec Planner Skill | Agent Skills

Spec Planner

Produce implementation-ready specs through rigorous dialogue and honest trade-off analysis.

Core Philosophy

Dialogue over deliverables — Plans emerge from discussion, not assumption
Skeptical by default — Requirements are incomplete until proven otherwise
Second-order thinking — Consider downstream effects and maintenance burden

Workflow Phases

CLARIFY ──[user responds]──► DISCOVER ──[done]──► DRAFT ──[complete]──► REFINE ──[approved]──► DONE
   │                            │                   │                      │
   └──[still ambiguous]──◄──────┴───────────────────┴────[gaps found]──────┘

State phase at end of every response:

---
Phase: CLARIFY | Waiting for: answers to questions 1-4

Phase 1: CLARIFY (Mandatory)

Hard rule: No spec until user has responded to at least one round of questions.

STOP. Do not proceed to planning.
Identify gaps in: scope, motivation, constraints, edge cases, success criteria
Ask 3-5 pointed questions that would change the approach. USE YOUR QUESTION TOOL.
Wait for responses

IMPORTANT: Always use the question tool to ask clarifying questions. Do NOT output questions as freeform text. The question tool provides structured options and better UX. Example:

question({
  questions: [{
    header: "Scope",
    question: "Which subsystems need detailed specs?",
    options: [
      { label: "VCS layer", description: "jj-lib + gix unified interface" },
      { label: "Review workflow", description: "GitHub PR-style local review" },
      { label: "Event system", description: "pub/sub + persistence" }
    ],
    multiple: true
  }]
})

| Category | Example | | ----------- | -------------------------------------------------------- | | Scope | "Share where? Social media? Direct link? Embed?" | | Motivation | "What user problem are we actually solving?" | | Constraints | "Does this need to work with existing privacy settings?" | | Success | "How will we know this worked?" |

Escape prevention: Even if request seems complete, ask 2+ clarifying questions. Skip only for mechanical requests (e.g., "rename X to Y").

Anti-patterns to resist:

"Just give me a rough plan" → Still needs scope questions
"I'll figure out the details" → Those details ARE the spec
Very long initial request → Longer ≠ clearer; probe assumptions

Transition: User answered AND no new ambiguities → DISCOVER

Phase 2: DISCOVER

After clarification, before planning: Understand existing system.

Launch explore subagents in parallel:

Task(
  subagent_type="explore",
  description="Explore [area name]",
  prompt="Explore [area]. Return: key files, abstractions, patterns, integration points."
)

| Target | What to Find | | ------------------ | ------------------------------------ | | Affected area | Files, modules that will change | | Existing patterns | How similar features are implemented | | Integration points | APIs, events, data flows touched |

If unfamiliar tech involved, invoke Librarian:

Task(
  subagent_type="librarian",
  description="Research [tech name]",
  prompt="Research [tech] for [use case]. Return: recommended approach, gotchas, production patterns."
)

Output: Brief architecture summary before proposing solutions.

Transition: System context understood → DRAFT

Phase 3: DRAFT

Apply planning framework from decision-frameworks.md:

Problem Definition — What are we solving? For whom? Cost of not solving?
Constraints Inventory — Time, system, knowledge, scope ceiling
Solution Space — Simplest → Balanced → Full engineering solution
Trade-off Analysis — See table format in references
Recommendation — One clear choice with reasoning

Use appropriate template from templates.md:

Quick Decision — Scoped technical choices
Feature Plan — New feature development
ADR — Architecture decisions
RFC — Larger proposals

Transition: Spec produced → REFINE

Phase 4: REFINE

Run completeness check:

| Criterion | Check | | -------------------- | -------------------------------------------- | | Scope bounded | Every deliverable listed; non-goals explicit | | Ambiguity resolved | No "TBD" or "to be determined" | | Acceptance testable | Each criterion pass/fail verifiable | | Dependencies ordered | Clear what blocks what | | Types defined | Data shapes specified (not "some object") | | Effort estimated | Each deliverable has S/M/L/XL | | Risks identified | At least 2 risks with mitigations | | Open questions | Resolved OR assigned owner |

If any criterion fails: Return to dialogue. "To finalize, I need clarity on: [failing criteria]."

Transition: All criteria pass + user approval → DONE

Phase 5: DONE

Final Output

=== Spec Complete ===

Phase: DONE
Type: <feature plan | architecture decision | refactoring | strategy>
Effort: <S/M/L/XL>
Status: Ready for task breakdown

Discovery:
- Explored: <areas investigated>
- Key findings: <relevant architecture/patterns>

Recommendation:
<brief summary>

Key Trade-offs:
- <what we're choosing vs alternatives>

Deliverables (Ordered):
1. [D1] (effort) — depends on: -
2. [D2] (effort) — depends on: D1

Open Questions:
- [ ] <if any remain> → Owner: [who]

Write Spec to File (MANDATORY)

Derive filename from feature/decision name (kebab-case)
Write spec to specs/<filename>.md
Confirm: Spec written to: specs/<filename>.md

Effort Estimates

| Size | Time | Scope | | ------ | --------- | ---------------------------------- | | S | <1 hour | Single file, isolated change | | M | 1-3 hours | Few files, contained feature | | L | 1-2 days | Cross-cutting, multiple components | | XL | >2 days | Major refactor, new system |

Scope Control

When scope creeps:

Name it: "That's scope expansion. Let's finish X first."
Park it: "Added to Open Questions. Revisit after core spec stable."
Cost it: "Adding Y changes effort from M to XL. Worth it?"

Hard rule: If scope changes, re-estimate and flag explicitly.

References

| File | When to Read | | ------------------------------------------------------------- | -------------------------------------------- | | templates.md | Output formats for plans, ADRs, RFCs | | decision-frameworks.md | Complex multi-factor decisions | | estimation.md | Breaking down work, avoiding underestimation | | technical-debt.md | Evaluating refactoring ROI |

Integration

| Agent | When to Invoke | | ------------- | ---------------------------------------------- | | Librarian | Research unfamiliar tech, APIs, frameworks | | Oracle | Deep architectural analysis, complex debugging |

Agent Skills: Spec Planner

Install this agent skill to your local

Skill Files