tranhieutt/map-systems

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name: map-systems description: "Creates a visual and textual map of the project systems, services, data flows, and integration boundaries. Use when documenting system architecture or when the user mentions system map, architecture diagram, or service boundaries." argument-hint: "[optional: 'next' to pick highest-priority undesigned system, or a system name to hand off to /design-system]" user-invocable: true allowed-tools: Read, Glob, Grep, Write, Edit, AskUserQuestion, TodoWrite context: fork agent: technical-director effort: 3 when_to_use: "When decomposing a product concept into individual systems, mapping dependencies, and prioritizing design order"

When this skill is invoked:

1. Parse Arguments

Two modes:

• No argument: /map-systems — Run the full decomposition workflow (Phases 1-5) to create or update the systems index.
• next: /map-systems next — Pick the highest-priority undesigned system from the index and hand off to /design-system (Phase 6).

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2. Phase 1: Read Concept (Required Context)

Read the product concept and any existing design work. This provides the raw material for systems decomposition.

Required:

• Read design/docs/product-concept.md — fail with a clear message if missing:

  "No product concept found at design/docs/product-concept.md. Run /brainstorm first to create one, then come back to decompose it into systems."

Optional (read if they exist):

• Read design/docs/product-pillars.md — pillars constrain priority and scope
• Read design/docs/systems-index.md — if exists, resume from where it left off (update, don't recreate from scratch)
• Glob design/docs/*.md — check which system PRDs already exist

If the systems index already exists:

• Read it and present current status to the user
• Use AskUserQuestion to ask: "The systems index already exists with [N] systems ([M] designed, [K] not started). What would you like to do?"
  • Options: "Update the index with new systems", "Design the next undesigned system", "Review and revise priorities"

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3. Phase 2: Systems Enumeration (Collaborative)

Extract and identify all systems the product needs. This is the creative core of the skill — it requires human judgment because concept docs rarely enumerate every system explicitly.

Step 2a: Extract Explicit Systems

Scan the product concept for directly mentioned systems and mechanics:

• Core Mechanics section (most explicit)
• Core Loop section (implies what systems drive each loop tier)
• Technical Considerations section (networking, procedural generation, etc.)
• MVP Definition section (required features = required systems)

Step 2b: Identify Implicit Systems

For each explicit system, identify the hidden systems it implies. Products always need more systems than the concept doc mentions. Use this inference pattern:

• "Inventory" implies: item database, equipment slots, weight/capacity rules, inventory UI, item serialization for save/load
• "Combat" implies: damage calculation, health system, hit detection, status effects, enemy AI, combat UI (health bars, damage numbers), death/respawn
• "Open world" implies: streaming/chunking, LOD system, fast travel, map/minimap, point of interest tracking, world state persistence
• "Multiplayer" implies: networking layer, lobby/matchmaking, state synchronization, anti-cheat, network UI (ping, user list)
• "Crafting" implies: recipe database, ingredient gathering, crafting UI, success/failure mechanics, recipe discovery/learning
• "Dialogue" implies: dialogue tree system, dialogue UI, choice tracking, NPC state management, localization hooks
• "Progression" implies: XP system, level-up mechanics, skill tree, unlock tracking, progression UI, progression save data

Explain in conversation text why each implicit system is needed (with examples).

Step 2c: User Review

Present the enumeration organized by category. For each system, show:

• Name
• Category
• Brief description (1 sentence)
• Whether it was explicit (from concept) or implicit (inferred)

Then use AskUserQuestion to capture feedback:

• "Are there systems missing from this list?"
• "Should any of these be combined or split?"
• "Are there systems listed that this product does NOT need?"

Iterate until the user approves the enumeration.

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4. Phase 3: Dependency Mapping (Collaborative)

For each system, determine what it depends on. A system "depends on" another if it cannot function without that other system existing first.

Step 3a: Map Dependencies

For each system, list its dependencies. Use these dependency heuristics:

• Input/output dependencies: System A produces data System B needs
• Structural dependencies: System A provides the framework System B plugs into
• UI dependencies: Every business system has a corresponding UI system that depends on it (but UI is designed after the business system)

Step 3b: Sort by Dependency Order

Arrange systems into layers:

1. Foundation: Systems with zero dependencies (designed and built first)
2. Core: Systems depending only on Foundation systems
3. Feature: Systems depending on Core systems
4. Presentation: UI and feedback systems that wrap business systems
5. Polish: Meta-systems, tutorials, analytics, accessibility

Step 3c: Detect Circular Dependencies

Check for cycles in the dependency graph. If found:

• Highlight them to the user
• Propose resolutions (interface abstraction, simultaneous design, breaking the cycle by defining a contract between the two systems)

Step 3d: Present to User

Show the dependency map as a layered list. Highlight:

• Any circular dependencies
• Any "bottleneck" systems (many others depend on them — these are high-risk)
• Any systems with no dependents (leaf nodes — lower risk, can be designed late)

Use AskUserQuestion to ask: "Does this dependency ordering look right? Any dependencies I'm missing or that should be removed?"

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5. Phase 4: Priority Assignment (Collaborative)

Assign each system to a priority tier based on what milestone it's needed for.

Step 4a: Auto-Assign Based on Concept

Use these heuristics for initial assignment:

• MVP: Systems mentioned in the concept's "Required for MVP" section, plus their Foundation-layer dependencies
• Vertical Slice: Systems needed for a complete experience in one area
• Alpha: All remaining business systems
• Full Vision: Polish, meta, and nice-to-have systems

Step 4b: User Review

Present the priority assignments in a table. For each tier, explain why systems were placed there.

Use AskUserQuestion to ask: "Do these priority assignments match your vision? Which systems should be higher or lower priority?"

Explain reasoning in conversation: "I placed [system] in MVP because the core loop requires it — without [system], the 30-second loop can't function."

Step 4c: Determine Design Order

Combine dependency sort + priority tier to produce the final design order:

1. MVP Foundation systems first
2. MVP Core systems second
3. MVP Feature systems third
4. Vertical Slice Foundation/Core systems
5. ...and so on

This is the order the team should write PRDs in.

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6. Phase 5: Create Systems Index (Write)

Step 5a: Draft the Document

Using the template at .claude/docs/templates/systems-index.md, populate the systems index with all data from Phases 2-4:

• Fill the enumeration table
• Fill the dependency map
• Fill the recommended design order
• Fill the high-risk systems
• Fill progress tracker (all systems "Not Started" initially, unless PRDs already exist)

Step 5b: Approval

Present a summary of the document:

• Total systems count by category
• MVP system count
• First 3 systems in the design order
• Any high-risk items

Ask: "May I write the systems index to design/docs/systems-index.md?"

Wait for approval. Write the file only after "yes."

Step 5c: Update Session State

After writing, update production/session-state/active.md with:

• Task: Systems decomposition
• Status: Systems index created
• File: design/docs/systems-index.md
• Next: Design individual system PRDs

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7. Phase 6: Design Individual Systems (Handoff to /design-system)

This phase is entered when:

• The user says "yes" to designing systems after creating the index
• The user invokes /map-systems [system-name]
• The user invokes /map-systems next

Step 6a: Select the System

• If a system name was provided, find it in the systems index
• If next was used, pick the highest-priority undesigned system (by design order)
• If the user just finished the index, ask: "Would you like to start designing individual systems now? The first system in the design order is [name]. Or would you prefer to stop here and come back later?"

Use AskUserQuestion for: "Start designing [system-name] now, pick a different system, or stop here?"

Step 6b: Hand Off to /design-system

Once a system is selected, invoke the /design-system [system-name] skill.

The /design-system skill handles the full PRD authoring process:

• Gathers context from product concept, systems index, and dependency PRDs
• Creates a file skeleton immediately
• Walks through all 8 required sections one at a time (collaborative, incremental)
• Cross-references existing docs to prevent contradictions
• Routes to specialist agents for domain expertise
• Writes each section to file as soon as it's approved
• Runs /design-review when complete
• Updates the systems index

Do not duplicate the /design-system workflow here. This skill owns the systems index; /design-system owns individual system PRDs.

Step 6c: Loop or Stop

After /design-system completes, use AskUserQuestion:

• "Continue to the next system ([next system name])?"
• "Pick a different system?"
• "Stop here for this session?"

If continuing, return to Step 6a.

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8. Phase 7: Suggest Next Steps

After the systems index is created (or after designing some systems), suggest the appropriate next actions:

• "Run /design-system [system-name] to write the next system's PRD"
• "Run /design-review [path] on each completed PRD to validate quality"
• "Run /gate-check pre-production to check if you're ready to start building"
• "Prototype the highest-risk system with /prototype [system]"
• "Plan the first implementation sprint with /sprint-plan new"

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Collaborative Protocol

This skill follows the collaborative design principle at every phase:

1. Question -> Options -> Decision -> Draft -> Approval at every step
2. AskUserQuestion at every decision point (Explain -> Capture pattern):
   • Phase 2: "Missing systems? Combine or split?"
   • Phase 3: "Dependency ordering correct?"
   • Phase 4: "Priority assignments match your vision?"
   • Phase 5: "May I write the systems index?"
   • Phase 6: "Start designing, pick different, or stop?" then hand off to /design-system
3. "May I write to [filepath]?" before every file write
4. Incremental writing: Update the systems index after each system is designed
5. Handoff: Individual PRD authoring is owned by /design-system, which handles incremental section writing, cross-referencing, design review, and index updates
6. Session state updates: Write to production/session-state/active.md after each milestone (index created, system designed, priorities changed)

Never auto-generate the full systems list and write it without review. Never start designing a system without user confirmation. Always show the enumeration, dependencies, and priorities for user validation.

Protocol

• Question: AskUserQuestion at every phase — missing systems, dependency ordering, priority assignments
• Options: Phase 2 — systems enumeration reviewed and adjusted collaboratively before proceeding
• Decision: User approves enumeration, dependency map, and priority tiers before writing
• Draft: Systems index summary shown before saving
• Approval: "May I write the systems index to design/docs/systems-index.md?"

Output

Deliver exactly:

• Systems index saved to design/docs/systems-index.md — all systems enumerated with dependencies and MVP tier
• Dependency map — which systems must be designed before others
• Design order — priority-ranked list of systems to PRD next
• Next skill: /design-system [first-priority-system]