Source Architecture From Code

Sync Architecture Skill

Keeps {{specs_dir}}/architecture.md synchronized with actual implementation decisions.

Pre-flight: Model Recommendation

Your current effort level is {{effort_level}}.

Skip this step silently if effort is high, xhigh, or max (the scale is low "You're working from ` (inside **[cwd-project]**), but the selected Groundwork project is **[selected-project]** ([selected-project-path]/). What would you like to do?" > - "Switch to [cwd-project]" > - "Stay with [selected-project]" If the user switches, invoke Skill(skill="groundwork:select-project")`.

• If CWD doesn't match any project → proceed without warning (shared directory).

1. Proceed with the resolved project context. All {{specs_dir}}/ paths will resolve to the correct location.

File Locations

• Target: Architecture document (may be single file or directory)
• Single file: {{specs_dir}}/architecture.md
• Directory: {{specs_dir}}/architecture/ (content split across files)
• Context: Current session history, codebase changes

Detection: Check for single file first (takes precedence), then directory.

When to Trigger

This skill should activate when:

• User explicitly invokes /groundwork:source-architecture-from-code
• Session involved architectural decisions (new tech choices, pattern changes)
• Implementation deviated from documented architecture
• New components or integrations were added

Workflow Overview

1. Analyze Session - Review what happened this session
2. Detect Changes - Identify architectural implications
3. Propose Updates - Draft specific changes to architecture doc
4. Apply Changes - Update document with user approval

Step 1: Analyze Session

Review the current session for:

Explicit Decisions:

• "Let's use X instead of Y"
• "We should add a cache layer"
• "This needs to be async"

Implicit Decisions (from implementation):

• New dependencies added (package.json, requirements.txt)
• New services/components created
• New integrations configured
• Database schema changes

Deviations:

• Implementation differs from architecture doc
• Workarounds that changed the design
• Scope changes affecting architecture

Step 2: Detect Change Categories

| Category | Signal | Single file section | Directory mode file | |----------|--------|---------------------|---------------------| | New component | New service/module created | §4 Component Details | 04-components/.md (new file) | | Tech change | Different library/framework used | §3 System Overview, relevant DR | 03-system-overview.md or 11-decisions/DR-NNN.md | | Data change | Schema migration, new store | §5 Data Architecture | 05-data.md | | Integration | New external service | §6 Integration Architecture | 06-integration.md | | Security | Auth/encryption changes | §7 Security Architecture | 07-security.md | | Infra | New environment, deployment change | §8 Infrastructure | 08-infrastructure.md | | Decision | Explicit "let's do X" statement | §11 Decision Records | 11-decisions/DR-NNN.md (new file) |

Step 3: Propose Updates

For each detected change, propose a specific update:

## Proposed Architecture Updates

### 1. New Decision Record

**Trigger:** You decided to use Redis for session caching instead of DynamoDB.

**Proposed addition to §11 Decision Records:**

### DR-00X: Session Cache Technology

**Status:** Accepted
**Date:** [today]
**Context:** [extracted from session]

**Options Considered:**
1. **DynamoDB** - Originally planned
   - Pros: AWS native, no new service
   - Cons: Overkill for simple key-value, higher latency
2. **Redis (ElastiCache)** - New choice
   - Pros: Sub-millisecond latency, built for sessions
   - Cons: Additional service to manage

**Decision:** Redis via ElastiCache

**Rationale:** [from session discussion]

---

### 2. Component Update

**Trigger:** Added new `NotificationService` module.

**Proposed addition to §4 Component Details:**

### 4.X Notification Service

**Responsibility:** Send transactional emails and push notifications

**Technology:** AWS SES + SNS

**Interfaces:**
- Exposes: Internal event handlers
- Consumes: EventBridge events

**Related Requirements:** PRD-XXX-REQ-NNN

---

Approve these updates? (yes/no/modify)

Step 4: Apply Changes

On approval:

1. Detect spec format - Check if architecture is single file or directory
2. Read current content:

• Single file: Read {{specs_dir}}/architecture.md
• Directory: Aggregate all .md files from {{specs_dir}}/architecture/

1. Route updates to appropriate files:

• Single file mode: Edit {{specs_dir}}/architecture.md directly
• Directory mode: Route each update:
• Decision records (DR-NNN) → Find or create in {{specs_dir}}/architecture/11-decisions/.md
• Components → {{specs_dir}}/architecture/04-components/.md
• Data architecture → {{specs_dir}}/architecture/05-data.md
• Security → {{specs_dir}}/architecture/07-security.md
• Updates to existing content → Find the file containing that content

1. Update "Last updated" timestamp
2. Add entry to change log if present

Important: Preserve existing content. Add to sections, don't replace unless explicitly correcting an error.

Step 4a: Auto-Split Check (single file mode only)

Skip this step if the architecture doc is already in directory mode.

After applying changes to the single-file architecture doc, check whether it should be split:

1. Count lines: wc -l {{specs_dir}}/architecture.md
2. Count decision records: number of ### DR-\d+ headings in the file

If lines >= 500 OR decision records >= 10:

• Invoke Skill(skill="groundwork:split-architecture") — this runs automatically with no user input needed.
• After the split completes, include in the session summary: "The architecture doc was automatically split into directory format at {{specs_dir}}/architecture/."

If neither threshold is crossed, continue silently.

Change Detection Heuristics

Strong signals (likely architectural):

• New infrastructure resources (Terraform, CDK changes)
• New service directories created
• Database migrations
• New external API integrations
• Changes to authentication/authorization
• New environment variables for services

Weak signals (maybe architectural):

• New utility functions
• Refactoring within existing components
• Bug fixes
• Test additions
• Documentation updates

Focus on strong signals. Ask about weak signals only if they seem significant.

Session Summary Format

At session end, provide summary:

## Architecture Sync Summary

**Session Date:** [date]

### Changes Detected:
1. [Change 1] → Proposed DR-00X
2. [Change 2] → Updated §4.3
3. [Change 3] → No architecture impact (implementation detail)

### Architecture Document:
- [X] Updated with approved changes
- [ ] No changes needed
- [ ] Changes pending user review

### Open Items:
- [Any unresolved architectural questions from session]

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: etr
• Source: etr/groundwork
• License: MIT

Install and usage instructions live in the source repository linked above.