Spec-Driven Development (IX)

Overview

Transform user-provided issue or tracking text (no tracker integration required) into structured specifications following GitHub spec-kit methodology: clear separation, progressive disclosure, minimal duplication.

When to use: User wants SDD / spec planning for an IX change and supplies (or will supply) a tracking/issue identifier plus title, description, and acceptance criteria as plain text.

Required input (no tracker integration)

Before Phase 1, confirm you have:

1. Tracking/issue identifier (e.g. IX-3896, issue number, ticket key) — if missing, ask once; if still missing, derive a short folder slug from the title (lowercase, hyphens, max ~40 chars).
2. Issue title (summary line).
3. Description — user story, context, bullets, links as pasted.
4. Acceptance criteria — pasted AC block or checklist from the issue/tracking source.

If the user only pastes prose without clear AC, extract implied AC into the spec and add a Clarifications note listing assumptions.

Do not call tracker APIs or assume an MCP; treat the chat message as the source of truth.

Key principles

1. Separation: spec.md (WHAT), plan.md (HOW), tasks.md (DO) — no duplication.
2. Tech-agnostic specs: Requirements do not name Stencil/React/etc.
3. Size-aware output: XS compact; L fuller (see below).
4. Line limits: Each artifact file under 500 lines.
5. Progressive disclosure: Read spec → plan → tasks when implementing.

Workflow phases

Pasted issue text → Specify → Review → Clarify → Review → Plan → Review → Tasks → Review → Implement
                    ↓                  ↓                 ↓                ↓
                  spec.md            spec.md           plan.md          tasks.md

Mandatory phase gates:

After creating or updating each artifact, stop and ask the user to review the created file before continuing:

1. After spec.md: ask whether to continue to planning or revise the spec.
2. After updated spec.md clarifications: ask whether to continue to planning or revise the clarified spec.
3. After plan.md: ask whether to continue to task breakdown or revise the plan.
4. After tasks.md: ask whether to implement, revise tasks, or stop at handoff.

Do not proceed to the next phase automatically after writing an artifact. If the runtime provides an ask_user tool, use it for these phase gates instead of asking in plain text.

If the XS strategy omits spec.md or tasks.md, skip only the omitted file's review gate; still stop after the merged plan.md and ask the user to review it before implementation.

Phase 1: Specify (requirements)

Create spec.md from the pasted issue only (optional: spawn a read-only explore subagent for codebase context after spec is drafted if gaps exist — do not block spec on repo-wide search).

Output path: .sdd/{TRACKING_ID}/spec.md (use the agreed tracking/issue identifier or slug for {TRACKING_ID}).

Review gate: After writing spec.md, stop and ask the user to review .sdd/{TRACKING_ID}/spec.md. Continue only when the user approves moving to planning; otherwise revise spec.md first.

Frontmatter:

---
tracking_id: {ID or slug}
feature: {TITLE}
date: {ISO date}
status: ready-for-planning
source: user-pasted-issue
---

Body template (adapt length to size tier):

# Feature Spec: {TITLE}

## User input (from issue)
{2–5 lines summarizing pasted description — no copy-paste dump of entire ticket}

## User scenarios and testing

### US1 [P1] - {Scenario}
**As** {role}
**I want** {goal}
**So that** {benefit}

**Acceptance scenarios:**
**Given** {context}
**When** {action}
**Then** {outcome}

**Edge cases:** {if any}

## Requirements

### Functional requirements
**FR-001**: {requirement}
**FR-002**: {requirement}

### Key entities
{Only if data or domain models matter}

## Success criteria
**SC-001**: {measurable outcome}
**SC-002**: {measurable outcome}

## Assumptions
{Scope boundaries, dependencies on other IX areas}

Size guide (spec.md only):

• XS: ~40 lines
• S: ~80 lines
• M: ~100 lines
• L: ~150 lines

Phase 2: Clarify (optional)

If requirements are ambiguous, ask targeted questions in chat; when answered, append to spec.md:

## Clarifications

**Q1**: …
**A**: …

Review gate: After adding clarifications, stop and ask the user to review the updated .sdd/{TRACKING_ID}/spec.md. Continue only when the user approves moving to planning; otherwise revise spec.md first.

Phase 3: Plan (technical approach)

Output: .sdd/{TRACKING_ID}/plan.md

1. Read spec.md.
2. Align with IX repo: skim CONTRIBUTING.md and relevant package/component paths touched; follow existing patterns in the monorepo.
3. Record technical decisions with short rationale; do not repeat requirements from spec.md — reference them (See spec.md US1).

Plan frontmatter:

---
tracking_id: {ID or slug}
phase: plan
created: {ISO date}
depends_on: []
---

Sections: Summary, Technical context (language, packages, tests), Architecture (decisions with alternatives rejected), Implementation structure, Risks and mitigations, Deployment strategy only if non-trivial.

Review gate: After writing plan.md, stop and ask the user to review .sdd/{TRACKING_ID}/plan.md. Continue only when the user approves creating tasks; otherwise revise plan.md first.

Size guide (plan.md):

• XS: merge spec + plan into a single plan.md only (~80 lines total) — skip separate spec.md only when doing XS merge (see XS strategy below).
• S: ~120 lines
• M: ~150 lines
• L: ~200 lines

Phase 4: Tasks (implementation steps)

Output: .sdd/{TRACKING_ID}/tasks.md

Ordered steps; each task: id, file path in repo, action, optional snippet, dependencies. Mark parallelizable tasks with [P]. Do not repeat plan rationale.

Review gate: After writing tasks.md, stop and ask the user to review .sdd/{TRACKING_ID}/tasks.md. Implement only if the user explicitly approves implementation; otherwise revise tasks.md or stop at handoff.

Size guide (tasks.md):

• XS: omit tasks.md (implement from merged plan).
• S: ~100 lines
• M: ~150 lines
• L: ~200 lines

Phase 5: Research (optional)

Create research.md only for unusual dependency or API verification — not for routine Stencil/Playwright usage.

Output: .sdd/{TRACKING_ID}/research.md (<300 lines).

XS output strategy

For XS (<~2h) work:

• Produce one file: .sdd/{TRACKING_ID}/plan.md (~80 lines) that merges concise requirements + approach + minimal task list + validation checklist.
• Omit separate spec.md / tasks.md unless the user explicitly wants full spec-kit layout.
• Stop after writing the merged plan.md and ask the user to review it before implementation.

S / M / L output strategy

Tier	Outputs	Approx. total lines
S	spec.md + plan.md + tasks.md	~300
M	spec.md + plan.md + tasks.md	~400
L	spec.md + plan.md + tasks.md (+ optional research.md)	~600

Classify size from pasted story points, AC count, and breadth (single component vs cross-package).

Anti-duplication rules

Before each paragraph:

1. Already in spec.md? → Link, do not repeat.
2. Technical decision? → plan.md only.
3. Implementation step? → tasks.md only.
4. Obvious to an IX maintainer? → Skip (standard monorepo test commands, changeset rules — point to existing skills if needed).
5. Project-wide rule? → Reference CONTRIBUTING.md or the relevant package README.

Cross-reference pattern:

See spec.md US1 for acceptance criteria.
See plan.md Architecture for rationale.

File layout

.sdd/{TRACKING_ID}/
├── spec.md       # Requirements (tech-agnostic)
├── plan.md       # Technical approach
├── tasks.md      # Implementation steps
└── research.md   # Optional tech verification

Do not generate narrative.md or standalone alternatives.md — keep decisions inline in plan.md.

Context management

• Main chat: clarify scope, write plan.md / tasks.md, discuss trade-offs.
• Read-only exploration: large codebase search to ground plan.md paths — use sparingly after spec.md exists.

Implementation handoff

When artifacts are ready:

Specification complete for {TRACKING_ID}.

Files:
- spec.md — requirements
- plan.md — technical approach
- tasks.md — steps (if created)

Next: implement a task, all tasks in order, or revise the plan — say which you prefer.

Quality checklist

spec.md: Tech-agnostic; Given/When/Then where applicable; numbered FRs; measurable success criteria; <500 lines.

plan.md: No requirement duplication; decisions with 1–2 line rationale; references spec; IX-realistic paths; <500 lines.

tasks.md: Exact repo paths; dependency order; [P] for parallel; no decision essays; <500 lines.

Overall: No cross-file duplication; size tier matches work; each file has one job.

IX-specific notes

• Prefer paths under packages/core, packages/angular, packages/react, packages/documentation, etc., as appropriate — discover real paths from the tree, do not invent directories.
• Testing and release hygiene: use existing project skills (component tests, Storybook a11y, changesets) when the user’s workflow requires them; do not restate full skill bodies here.

References

• GitHub spec-kit
• Project skill definition: .github/skills/sdd/SKILL.md — this repo skill uses pasted issue/tracking text and .sdd/… for generated artifacts.