C3 Onboarding

Initialize C3 architecture documentation using a 3-stage workflow with gates.

REQUIRED: Load References

Load immediately:

•../../references/skill-harness.md - Red flags and complexity rules
•../../references/layer-navigation.md - How to traverse C3 docs

Load for templating:

•../../templates/adr-000.md - Adoption ADR (drives the workflow)
•../../templates/context.md - Context template
•../../templates/container.md - Container template
•../../templates/component.md - Component template
•../../templates/ref.md - Reference template

Workflow Overview

mermaid

flowchart TD
    GOAL([Goal]) --> S0

    subgraph S0["Stage 0: Inventory"]
        S0_DISCOVER[Discover codebase] --> S0_ASK{Gaps?}
        S0_ASK -->|Yes| S0_SOCRATIC[Socratic] --> S0_DISCOVER
        S0_ASK -->|No| S0_LIST[List items + diagram]
    end

    S0_LIST --> G0{Inventory complete?}
    G0 -->|No| S0_DISCOVER
    G0 -->|Yes| S1

    subgraph S1["Stage 1: Details"]
        S1_CONTAINER[Per container] --> S1_INT[Internal comp]
        S1_CONTAINER --> S1_LINK[Linkage comp]
        S1_INT --> S1_REF[Extract refs]
        S1_LINK --> S1_REF
        S1_REF --> S1_ASK{Questions?}
        S1_ASK -->|Yes| S1_SOCRATIC[Socratic] --> S1_CONTAINER
        S1_ASK -->|No| S1_NEXT{More?}
        S1_NEXT -->|Yes| S1_CONTAINER
    end

    S1_NEXT -->|No| G1{Fix inventory?}
    G1 -->|Yes| S0_DISCOVER
    G1 -->|No| S2

    subgraph S2["Stage 2: Finalize"]
        S2_CHECK[Integrity checks]
    end

    S2_CHECK --> G2{Issues?}
    G2 -->|Inventory| S0_DISCOVER
    G2 -->|Detail| S1_CONTAINER
    G2 -->|None| DONE([Implemented])

Critical: All questioning MUST use AskUserQuestion tool - never plain text questions.

Progress Checklist

Copy and track as you work:

code

Onboarding Progress:
- [ ] Stage 0: All items inventoried (context, containers, components, refs)
- [ ] Stage 0: ADR-000 created with discovery tables filled
- [ ] Gate 0: Inventory complete, proceed to Details
- [ ] Stage 1: All container README.md created
- [ ] Stage 1: All component docs created
- [ ] Stage 1: All refs documented
- [ ] Gate 1: No new items discovered
- [ ] Stage 2: Integrity checks pass
- [ ] Gate 2: /c3 audit passes
- [ ] ADR-000 marked implemented

Stage 0: Inventory

Goal: Discover EVERYTHING before creating any docs.

0.1 Create ADR-000

Run init script and create ADR-000 from template:

bash

PROJECT="<name>" C1="<container1>" C2="<container2>" "${CLAUDE_PLUGIN_ROOT}/scripts/c3-init.sh"

0.2 Context Discovery

Read codebase structure. Capture template arguments in ADR-000 Context Discovery table:

Arg	Value
PROJECT	What is this system called?
GOAL	Why does this system exist?
SUMMARY	One-sentence description

Use AskUserQuestion for gaps:

code

Q: "I see apps/api/ and apps/web/. Are these separate containers?"
Options: [Separate containers, Single monolith, Monorepo with shared code]

0.3 Container Discovery

For each potential container, capture in ADR-000 Container Discovery table:

N	CONTAINER_NAME	GOAL	SUMMARY

Note: N maps to init script variable (C1=1, C2=2, etc.)

Use AskUserQuestion:

code

Q: "Is apps/api/ a deployable backend API?"
Options: [Yes - Backend API, No - Library/shared code, Need more context]

0.4 Component Discovery (Brief)

For each container, scan for components. Capture in ADR-000 Component Discovery table:

N	NN	COMPONENT_NAME	CATEGORY	GOAL	SUMMARY

Categorization (use lowercase in table):

•foundation (01-09): Primitives others depend on (Router, AuthProvider, Database)
•feature (10+): Domain-specific (UserService, CheckoutFlow, Dashboard)

Use AskUserQuestion:

code

Q: "AuthMiddleware is imported by 15 files. Foundation or Feature?"
Options: [Foundation - others depend on it, Feature - domain logic, Need more context]

0.5 Ref Discovery

Look for patterns that repeat across components. Capture in ADR-000 Ref Discovery table:

SLUG	TITLE	GOAL	Applies To

Common ref candidates:

•Error handling patterns
•Form patterns
•Query/data fetching patterns
•Design system principles
•User flows / IA

0.6 Overview Diagram

Generate mermaid diagram showing:

•Actors → Containers → External Systems
•Key linkages

Gate 0

Before proceeding, verify:

• Context args filled (PROJECT, GOAL, SUMMARY)
• All containers identified with args
• All components identified (brief) with args
• Cross-cutting refs identified
• Overview diagram generated

If gaps: Return to discovery with Socratic questioning.

Stage 1: Details

Goal: Create all docs from inventory.

1.1 Context Doc

Create .c3/README.md from context.md template using discovered args.

Fill:

•Goal section (from PROJECT, GOAL)
•Overview diagram
•Containers table with Goal Contribution column

1.2 Container Docs

For EACH container in inventory:

1.2.1 Create container README

Create .c3/c3-N-{slug}/README.md from container.md template.

Fill:

•Goal section
•Context Connection (how it serves parent)
•Components table with Goal Contribution column

1.2.2 Create component docs

For each component in this container:

Create .c3/c3-N-{slug}/c3-NNN-{component}.md from component.md template.

Fill:

•Goal section
•Container Connection
•Related Refs table

1.2.3 Handle discoveries

If new component found during documentation:

•Add to ADR-000 Component Discovery table
•Document conflict in Conflict Resolution table
•Continue (will verify at Gate 2)

1.3 Ref Docs

For each ref in inventory:

Create .c3/refs/ref-{slug}.md from ref.md template.

Fill:

•Goal section
•Content sections
•Update Cited By as you create component docs

Gate 1

Before proceeding, verify:

• All container README.md created
• All component docs created
• All refs documented
• No new items discovered (else → update ADR-000 inventory)

If new items discovered: Return to Stage 0, update ADR-000 discovery tables.

Stage 2: Finalize

Goal: Verify integrity across all docs.

2.1 Integrity Checks

Check	How to Verify
Context ↔ Container	Every container in ADR-000 appears in c3-0 Containers table
Container ↔ Component	Every component in container README has a doc
Component ↔ Component	Linkages documented in Container README
* ↔ Refs	Refs Cited By section matches component Related Refs

2.2 Run Audit

code

/c3 audit

Gate 2

Before marking complete, verify:

• All integrity checks pass
• /c3 audit passes

If issues:

•Inventory issues (missing container/component) → Gate 0
•Detail issues (wrong Goal, missing connection) → Gate 1
•Pass → Mark ADR-000 as implemented

Tiered Assumption Rules

Impact	Examples	Action
High	New External, boundary change, component reassignment	Ask first via AskUserQuestion
Low	Linkage reasoning, naming fix, add to inventory	Auto-proceed, note in Conflict Resolution

End-to-End Example

code

User: "Set up C3 for my project"

=== Stage 0: Inventory ===

[0.1] Run c3-init.sh, create ADR-000

[0.2] Context Discovery
Read codebase: apps/api/, apps/web/, packages/shared/

AskUserQuestion: "What is this system called?"
User: "Acme Platform"

AskUserQuestion: "Why does this system exist?"
User: "E-commerce platform for small businesses"

Fill ADR-000 Context Discovery:
| PROJECT | Acme Platform |
| GOAL | E-commerce platform for small businesses |
| SUMMARY | Full-stack e-commerce with API and web frontend |

[0.3] Container Discovery
AskUserQuestion: "Are apps/api/ and apps/web/ separate containers?"
User: "Yes"

Fill ADR-000 Container Discovery:
| 1 | API Backend | Handle business logic and data | REST API layer |
| 2 | Web Frontend | User interface | Next.js web app |

[0.4] Component Discovery
Scan apps/api/src/...
Found: auth/, products/, orders/, middleware/

AskUserQuestion: "AuthMiddleware - Foundation or Feature?"
User: "Foundation"

Fill ADR-000 Component Discovery:
| 1 | 01 | AuthMiddleware | foundation | Auth handling | JWT validation |
| 1 | 10 | ProductService | feature | Product CRUD | Catalog management |
...

[0.5] Ref Discovery
Pattern found: error handling in 5 components

Fill ADR-000 Ref Discovery:
| error-handling | Error Handling | Consistent errors | c3-101, c3-110 |

[Gate 0] ✓ All tables filled, proceed to Stage 1

=== Stage 1: Details ===

[1.1] Create .c3/README.md from context.md template
[1.2] Create .c3/c3-1-api/README.md + component docs
[1.2] Create .c3/c3-2-web/README.md + component docs
[1.3] Create .c3/refs/ref-error-handling.md

[Gate 1] ✓ All docs created, no new items

=== Stage 2: Finalize ===

[2.1] Integrity checks - all pass
[2.2] /c3 audit - passes

[Gate 2] ✓ Mark ADR-000 as implemented

Done!