System Archaeologist - Codebase Architecture Analysis

Overview

Analyze existing codebases through coordinated subagent exploration to produce comprehensive architecture documentation with C4 diagrams, subsystem catalogs, and architectural assessments.

Core principle: Systematic archaeological process with quality gates prevents rushed, incomplete analysis.

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Context Conservation (CRITICAL)

You are a COORDINATOR, not an analyst. Your primary context is precious - preserve it for orchestration decisions, not detailed code reading.

The Delegation Imperative

Task Type	Your Role	Subagent Role
Subsystem analysis	Spawn codebase-explorer	Read files, produce catalog entries
Validation	Spawn analysis-validator	Check contracts, produce reports
Diagram generation	Spawn diagram subagent	Generate Mermaid/PlantUML
Quality assessment	Spawn quality subagent	Analyze patterns, produce assessment
Security surface	Spawn security subagent	Map boundaries, flag concerns

What You DO (Coordinator):

• Create workspace and coordination plan
• Make orchestration decisions (parallel vs sequential)
• Spawn subagents with clear task specifications
• Read subagent outputs (summaries, not raw files)
• Make proceed/revise decisions based on validation
• Synthesize final deliverables from subagent work

What You DO NOT Do (Delegate Instead):

• Read implementation files directly (subagent reads, you get summary)
• Perform detailed pattern analysis (spawn specialist)
• Write catalog entries yourself (spawn codebase-explorer)
• Validate your own work (spawn analysis-validator)
• Generate diagrams from scratch (spawn diagram agent)

Rationalization Blockers

Thought	Reality
"I'll just quickly read this file"	Spawn subagent. Your context is for coordination.
"It's faster if I do it myself"	Subagents preserve your context for later decisions.
"Only a few files to check"	"Few" files become many. Delegate from the start.
"I need to understand the code"	You need to understand the STRUCTURE. Subagents report findings.
"Spawning overhead isn't worth it"	Context exhaustion is worse. Always delegate detailed work.

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When to Use

• User requests architecture documentation for existing codebase
• Need to understand unfamiliar system architecture
• Creating design docs for legacy systems
• Analyzing codebases of any size (small to large)
• User mentions: "analyze codebase", "architecture documentation", "system design", "generate diagrams"

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How to Access Reference Sheets

IMPORTANT: All reference sheets are located in the SAME DIRECTORY as this SKILL.md file.

When this skill is loaded from: skills/using-system-archaeologist/SKILL.md

Reference sheets like subsystem-discovery.md are at: skills/using-system-archaeologist/subsystem-discovery.md

NOT at: skills/subsystem-discovery.md ← WRONG PATH

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Mandatory Workflow

Step 1: Create Workspace (NON-NEGOTIABLE)

Before any analysis:

mkdir -p docs/arch-analysis-$(date +%Y-%m-%d-%H%M)/temp

Why this is mandatory:

• Organizes all analysis artifacts in one location
• Enables subagent handoffs via shared documents
• Provides audit trail of decisions
• Prevents file scatter across project

Common rationalization: "This feels like overhead when I'm pressured"

Reality: 10 seconds to create workspace saves hours of file hunting and context loss.

Step 1.5: Offer Deliverable Menu (MANDATORY)

After workspace creation, present deliverable options using AskUserQuestion tool.

See deliverable-options.md for the complete menu (Options A-G).

Key options:

• A) Full Analysis - Comprehensive documentation
• B) Quick Overview - Fast turnaround, documented limitations
• C) Architect-Ready - Full analysis + improvement planning
• E) Full + Security - Security surface mapping included
• F) Full + Quality - Test infrastructure + dependency analysis
• G) Comprehensive - Everything

Common rationalization: "User didn't specify, so I'll default to full analysis"

Reality: Always offer choice explicitly. Different needs require different outputs.

Step 2: Write Coordination Plan

After documenting deliverable choice, write 00-coordination.md:

## Analysis Plan
- Scope: [directories to analyze]
- Strategy: [Sequential/Parallel with reasoning]
- Time constraint: [if any, with scoping plan]
- Complexity estimate: [Low/Medium/High]

## Execution Log
- [timestamp] Created workspace
- [timestamp] [Next action]

Common rationalization: "I'll just do the work, documentation is overhead"

Reality: Undocumented work is unreviewable and non-reproducible.

Step 3: Holistic Assessment First

Before diving into details, perform systematic scan:

1. Directory structure - Map organization (feature? layer? domain?)
2. Entry points - Find main files, API definitions, config
3. Technology stack - Languages, frameworks, dependencies
4. Subsystem identification - Identify 4-12 major cohesive groups

Write findings to 01-discovery-findings.md

Common rationalization: "I can see the structure, no need to document it formally"

Reality: What's obvious to you now is forgotten in 30 minutes.

Step 4: Subagent Orchestration Strategy

Decision point: Sequential vs Parallel

Use SEQUENTIAL when:

• Project < 5 subsystems
• Subsystems have tight interdependencies
• Quick analysis needed (< 1 hour)

Use PARALLEL when:

• Project ≥ 5 independent subsystems
• Large codebase (20K+ LOC, 10+ plugins/services)
• Subsystems are loosely coupled

Common rationalization: "Solo work is faster than coordination overhead"

Reality: For large systems, orchestration overhead (5 min) saves hours of sequential work.

Step 5: Subagent Delegation Pattern

When spawning subagents for analysis:

Create task specification in temp/task-[subagent-name].md:

## Task: Analyze [specific scope]
## Context
- Workspace: docs/arch-analysis-YYYY-MM-DD-HHMM/
- Read: 01-discovery-findings.md
- Write to: 02-subsystem-catalog.md (append your section)

## Expected Output
Follow contract in documentation-contracts.md:
- Subsystem name, location, responsibility
- Key components (3-5 files/classes)
- Dependencies (inbound/outbound)
- Patterns observed
- Confidence level

## Validation Criteria
- [ ] All contract sections complete
- [ ] Confidence level marked
- [ ] Dependencies bidirectional (if A depends on B, B shows A as inbound)

Step 6: Validation Gates (MANDATORY)

After EVERY major document is produced, validate before proceeding.

SPAWN VALIDATION SUBAGENT (Required for ≥3 subsystems)

• Spawn dedicated validation subagent using Task tool
• Agent reads document + contract, produces validation report
• Write validation report to temp/validation-[document].md

Self-validation ONLY permitted when ALL conditions met:

1. Single-subsystem analysis (1-2 subsystems only)
2. Total analysis time < 30 minutes
3. YOU personally did ALL the work (no subagents involved)
4. AND you document validation EVIDENCE (not just checkmarks)

If ANY condition is not met → SPAWN VALIDATION SUBAGENT. No exceptions.

Validation Rationalization Blockers

Excuse	Reality
"We have 45 minutes, no time for validation"	Validation takes 5-10 minutes. Spawn validator.
"I already reviewed it while writing"	Self-review ≠ validation. Spawn validator.
"I'll do systematic self-validation"	Multiple subsystems require independent validator. Spawn validator.
"Most work is already done"	Prior work must be validated. Spawn validator.
"Time pressure - I'll document limitations instead"	Documented limitations don't excuse skipping validation. Spawn validator.
"It's a simple codebase"	Simple ≠ correct. Spawn validator.

Validation Status Meanings

• APPROVED → Proceed to next phase
• NEEDS_REVISION (warnings) → Fix non-critical issues, document as tech debt, proceed
• NEEDS_REVISION (critical) → BLOCK. Fix issues, re-validate. Max 2 retries, then escalate to user.

Step 7: Handle Validation Failures

When validator returns NEEDS_REVISION with CRITICAL issues:

1. Read validation report (temp/validation-*.md)
2. Identify specific issues (not general "improve quality")
3. Spawn original subagent again with fix instructions
4. Re-validate after fix
5. Maximum 2 retries - if still failing, escalate to user

DO NOT:

• Proceed to next phase despite BLOCK status
• Make fixes yourself without re-spawning subagent
• Rationalize "it's good enough"
• Question validator authority

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Working Under Pressure

Time Constraints Are Not Excuses to Skip Process

WRONG response: Skip workspace, skip validation, rush deliverables

RIGHT response: Scope appropriately while maintaining process

Example scoping for 3-hour deadline:

## Coordination Plan
- Time constraint: 3 hours until stakeholder presentation
- Strategy: SCOPED ANALYSIS with quality gates maintained
- Timeline:
  - 0:00-0:05: Create workspace, write coordination plan
  - 0:05-0:35: Holistic scan, identify all subsystems
  - 0:35-2:05: Focus on 3 highest-value subsystems (parallel analysis)
  - 2:05-2:35: Generate minimal viable diagrams (Context + Component only)
  - 2:35-2:50: Validate outputs
  - 2:50-3:00: Write executive summary with EXPLICIT limitations section

## Limitations Acknowledged
- Only 3/14 subsystems analyzed in depth
- No module-level dependency diagrams
- Confidence: Medium (time-constrained analysis)
- Recommend: Full analysis post-presentation

Key principle: Scoped analysis with documented limitations > complete analysis done wrong.

Extreme Pressure Handling

If user requests something genuinely impossible (e.g., "Complete 15-plugin analysis in 1 hour"):

Provide scoped alternatives:

A) Quick overview (1 hour): Holistic scan, plugin inventory, high-level diagram B) Focused deep-dive (1 hour): Pick 2-3 critical plugins, full analysis of those C) Use existing docs (15 min): Synthesize existing README.md, CLAUDE.md D) Reschedule (recommended): Full analysis takes 4-6 hours for this scale

DO NOT refuse entirely. Provide realistic scoped alternatives.

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Common Rationalizations (RED FLAGS)

If you catch yourself thinking ANY of these, STOP:

Excuse	Reality
"Time pressure makes trade-offs appropriate"	Process prevents rework. Skipping process costs MORE time.
"This feels like overhead"	5 minutes of structure saves hours of chaos.
"Working solo is faster"	Solo works for small tasks. Orchestration scales for large systems.
"I'll just write outputs directly"	Uncoordinated work creates inconsistent artifacts.
"Validation slows me down"	Validation catches errors before they cascade.
"I already checked it"	Self-review misses what fresh eyes catch.
"I can't do this properly in [short time]"	You can do SCOPED analysis properly. Document limitations.
"Rather than duplicate, I'll synthesize"	Existing docs ≠ systematic analysis. Do the work.
"Meeting-ready outputs" justify shortcuts	Stakeholders deserve accurate info, not rushed guesses.

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Specialist Subagent Integration

For complex codebases, leverage specialist subagents from other skillpacks.

See specialist-integration.md for:

• When to invoke specialists (by codebase type)
• Spawning pattern and output integration
• Cross-pack handoff points
• Technical accuracy escalation

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Workflow Summary

1. Create workspace (docs/arch-analysis-YYYY-MM-DD-HHMM/)
1.5. Offer deliverable menu (A/B/C/D/E/F/G) - user chooses scope
2. Write coordination plan (00-coordination.md) with deliverable choice
3. Holistic assessment → 01-discovery-findings.md
4. Decide: Sequential or Parallel? (document reasoning)
5. Spawn subagents for analysis → 02-subsystem-catalog.md
6. VALIDATE subsystem catalog (mandatory gate)
6.5. (Optional) Code quality assessment → 05-quality-assessment.md
6.6. (Optional) Security surface mapping → 07-security-surface.md
6.7. (Optional) Test infrastructure analysis → 09-test-infrastructure.md
6.8. (Optional) Dependency analysis → 10-dependency-analysis.md
7. Spawn diagram generation → 03-diagrams.md
8. VALIDATE diagrams (mandatory gate)
9. Synthesize final report → 04-final-report.md
10. VALIDATE final report (mandatory gate)
11. (Optional) Generate architect handover → 06-architect-handover.md
12. Provide cleanup recommendations for temp/

Every step is mandatory except optional steps (6.5-6.8, 11). No exceptions.

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Success Criteria

You have succeeded when:

• Workspace structure exists with all numbered documents
• Coordination log documents all major decisions
• All outputs passed validation gates
• Subagent orchestration used appropriately for scale
• Limitations explicitly documented if time-constrained

You have failed when:

• Files scattered outside workspace
• No coordination log showing decisions
• Validation skipped "to save time"
• Self-validated multi-subsystem work instead of spawning validator
• Worked solo despite clear parallelization opportunity
• Produced rushed outputs without limitation documentation

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Anti-Patterns

❌ Skip workspace creation "I'll just write files to project root"

❌ No coordination logging "I'll just do the work without documenting strategy"

❌ Work solo despite scale "Orchestration overhead isn't worth it"

❌ Skip validation subagent "I already reviewed it myself" / "I'll do systematic self-validation"

❌ Self-validate multi-subsystem work "Time constraints mean self-validation is acceptable" (NO - spawn validator)

❌ Bypass BLOCK status "The validation is too strict, I'll proceed anyway"

❌ Complete refusal under pressure "I can't do this properly in 3 hours, so I won't do it" (Should: Provide scoped alternative)

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Documentation Contracts

See individual skill files for detailed contracts:

• 01-discovery-findings.md contract → analyzing-unknown-codebases.md
• 02-subsystem-catalog.md contract → analyzing-unknown-codebases.md
• 03-diagrams.md contract → generating-architecture-diagrams.md
• 04-final-report.md contract → documenting-system-architecture.md
• 05-quality-assessment.md contract → assessing-code-quality.md
• 06-architect-handover.md contract → creating-architect-handover.md
• 07-security-surface.md contract → mapping-security-surface.md
• 08-incremental-report.md contract → incremental-analysis.md
• 09-test-infrastructure.md contract → analyzing-test-infrastructure.md
• 10-dependency-analysis.md contract → analyzing-dependencies.md
• Validation protocol → validating-architecture-analysis.md
• Language/framework patterns → language-framework-patterns.md
• Deliverable options → deliverable-options.md
• Specialist integration → specialist-integration.md