Claude-skill-registry 22-understand-deep-150

[22] UNDERSTAND. Deep research from all sources — internal (code, git, logs) AND external (web, docs, best practices). Use when choosing libraries, investigating solutions, understanding legal/technical questions, comparing approaches, or anytime you need comprehensive knowledge from both project context and world knowledge. Triggers on \"research\", \"investigate\", \"find best approach\", \"what do others do\", \"compare options\", or complex questions requiring multiple sources.

install
source · Clone the upstream repo
git clone https://github.com/majiayu000/claude-skill-registry
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/22-understand-deep-150" ~/.claude/skills/majiayu000-claude-skill-registry-22-understand-deep-150 && rm -rf "$T"
manifest: skills/data/22-understand-deep-150/SKILL.md
source content

Understand-Deep 150 Protocol

Core Principle: Research deeply from ALL sources — internal context AND external knowledge. Don't limit yourself to one world.

What This Skill Does

When you invoke this skill, you're researching from TWO worlds:

🏠 INTERNAL (Project Context)

  • Code — what's already implemented
  • Git history — why and when things changed
  • Logs — what actually happened
  • Config — how things are set up

🌍 EXTERNAL (World Knowledge)

  • Web search — how others solved similar problems
  • Documentation — official guidance and specs
  • Best practices — established patterns
  • Community — Stack Overflow, GitHub issues, forums

The Two Worlds of Research

🏠 INTERNAL (Project Context)        🌍 EXTERNAL (World Knowledge)
├── Code files                       ├── Web search
├── Git history/blame                ├── Official documentation
├── Comments & inline docs           ├── Stack Overflow / forums
├── Config files                     ├── Blog posts & tutorials
├── Tests (expected behavior)        ├── GitHub issues/discussions
├── Logs (actual behavior)           ├── Best practice guides
└── Project documentation            └── Comparison articles

Key Insight: Most questions need BOTH worlds. Internal tells you "what we have", external tells you "what's possible".

The 150% Research Rule

  • 100% Core: Research from primary relevant sources (internal OR external depending on question)
  • 50% Enhancement: Cross-check with the OTHER world (if started internal → check external, vice versa)

Real-World Research Scenarios

ScenarioInternal ResearchExternal Research
Choosing a libraryWhat's already used? Conflicts?Comparisons, benchmarks, community health
Legal questionContext, contracts, historyLaws, regulations, precedents
Architecture decisionCurrent structure, constraintsPatterns, case studies, trade-offs
Bug investigationCode, logs, git blameKnown issues, similar problems
Performance optimizationProfiling, bottlenecksBest practices, techniques
Security concernCurrent implementationVulnerabilities, OWASP, CVEs

When to Use Which Source

🔍 Understanding Existing Code

QuestionBest SourceTools*
"What does this code do?"Read the code
read_file
,
grep
"Why was it written this way?"Git blame/history
git log
,
git blame
"When did this change?"Git history
git log --follow
"What was the original intent?"Commits + PR descriptions
git show
,
git log

🌐 Finding Solutions

QuestionBest SourceTools*
"How do others solve X?"Web search
web_search
"What's the best practice?"Web + official docs
web_search
"Is there a library for X?"Web + package repos
web_search
"What are common pitfalls?"Web + Stack Overflow
web_search

📖 Understanding Context

QuestionBest SourceTools*
"What does this API do?"Official documentation
web_search
for docs
"What version is compatible?"Package docs + changelogs
web_search
,
read_file
"How has this evolved?"Git history
git log
,
git diff

*Tool names vary by agent — use equivalent available tools

Tool Abstraction Guide

Different agents have different tool names. Use what's available:

CapabilityClaude CodeCodexGeneric
Read files
read_file
view_file
file reading tool
Search code
grep
,
codebase_search
search
code search tool
Web search
web_search
search_web
internet search tool
Run commands
run_terminal_cmd
shell
terminal/shell tool
Git operationsterminal + gitterminal + gitgit via terminal

Rule: Use the tool that achieves the goal, regardless of its name.

Execution Protocol

Step 1: IDENTIFY WHAT YOU NEED

Clarify the knowledge gap:

  • What exactly do I need to know?
  • Is this about existing code or new solutions?
  • Do I need history/context or just current state?

Step 2: SELECT SOURCES

Choose appropriate sources based on need:

Need to understand existing code?
  → Read code + git history + comments

Need to find a solution approach?
  → Web search + best practices + similar projects

Need to debug something?
  → Logs + git blame + error searches

Need to integrate with external system?
  → Official docs + web search + examples

Step 3: GATHER FROM MULTIPLE SOURCES

Minimum 3 sources for important facts:

  • Primary source (code, official docs)
  • Secondary source (explanations, tutorials)
  • Validation source (tests, examples, community)

Step 4: CROSS-VALIDATE

Check for consistency:

  • Do sources agree?
  • Are there contradictions?
  • Which source is most authoritative?

Step 5: SYNTHESIZE

Combine findings into verified knowledge:

  • Core facts (verified)
  • Context (understood)
  • Confidence level (quantified)

Git History: Your Hidden Knowledge Source

Git history is often overlooked but invaluable:

When to Use Git

SituationGit CommandWhat You Learn
"Why is this code weird?"
git blame <file>
Who wrote it and when
"What was the intent?"
git log -p <file>
Changes over time
"When did this break?"
git bisect
Which commit caused issue
"What changed recently?"
git log --since="1 week"
Recent modifications
"How did this function evolve?"
git log -p -S "function_name"
History of specific code

Git Evidence Patterns

# Who wrote this line and why?
git blame path/to/file.js

# What changed in this file and why?
git log -p --follow path/to/file.js

# Find when a specific line was added
git log -S "specific code" --oneline

# What happened around a date?
git log --since="2024-01-01" --until="2024-02-01"

Web Search: Your External Brain

Web search is essential for:

  • Best practices and patterns
  • How others solved similar problems
  • Library/API documentation
  • Error message solutions
  • Community knowledge

Effective Web Search Patterns

"How to [specific task] in [language/framework]"
"[error message] solution"
"[library name] best practices"
"[problem] vs [alternative] comparison"
"[technology] production tips"

Output Format

When using Research-Deep 150:

🔬 **Research-Deep 150 Complete**

**Question:** [What we needed to know]

**🏠 Internal Research:**
- 📁 Code: [what we found in codebase]
- 📜 Git: [what history revealed]
- 📋 Context: [relevant project facts]

**🌍 External Research:**
- 🌐 Web: [what we found online]
- 📖 Docs: [official documentation]
- 💡 Best Practices: [established patterns]

**Synthesis:**
[Combined understanding from BOTH worlds]

**Recommendation:** [What to do based on research]

**Confidence:** [X]%
**Sources agree:** [Yes/Partial/No]
**Gaps:** [What we still don't know]

Evidence Quality Levels

LevelSourcesConfidence
Strong3+ agreeing sources, primary data90-100%
Good2-3 sources, mostly agree75-89%
Moderate1-2 sources, some assumptions50-74%
WeakSingle source or contradictions<50%

Operational Rules

  1. NEVER SINGLE SOURCE: Important facts need 3+ sources
  2. USE ALL AVAILABLE: Code, git, web, docs — use what's relevant
  3. CONTEXT MATTERS: Choose sources based on what you need to know
  4. GIT IS GOLD: History often explains the "why"
  5. WEB FOR PATTERNS: Others have solved your problem before
  6. CROSS-VALIDATE: Sources should agree or explain why not
  7. QUANTIFY CONFIDENCE: State how sure you are and why

Examples

❌ Without Research-Deep

Question: "Which date library should we use?"
AI: "Use moment.js, it's popular" (outdated advice)
Result: Chose deprecated library, had to migrate later

✅ With Research-Deep 150

Question: "Which date library should we use?"

🔬 Research-Deep 150:

🏠 Internal Research:
- 📁 Code: Currently using native Date, some formatting issues
- 📋 Context: Need timezone support, bundle size matters
- 📜 Git: Previous attempt with moment.js reverted (too heavy)

🌍 External Research:
- 🌐 Web: "best javascript date library 2024"
- 📖 Docs: Compared date-fns, dayjs, luxon
- 💡 Best Practices: moment.js deprecated, modern alternatives exist

Synthesis:
- moment.js is deprecated (external confirms)
- We tried it before, too heavy (internal confirms)
- date-fns: modular, tree-shakeable, good for bundle size
- dayjs: moment-like API, small size
- luxon: best for complex timezone work

Recommendation: dayjs for simple needs (2KB), date-fns for complex (modular)

Confidence: 92%

✅ Legal Question Example

Question: "Can we use this image in our product?"

🔬 Research-Deep 150:

🏠 Internal Research:
- 📁 Found image in /assets/hero.jpg
- 📜 Git: Added 2 years ago, no license info in commit
- 📋 Context: Used on marketing page

🌍 External Research:
- 🌐 Reverse image search: Found on Unsplash
- 📖 Unsplash license: Free for commercial use, no attribution required
- 💡 Best Practice: Still good to keep license record

Recommendation: Safe to use. Document source in assets README.

Confidence: 95%

Failure Modes & Recovery

FailureDetectionRecovery
Internal onlyNo external perspectiveAdd web search, docs
External onlyIgnoring project contextCheck code, git, configs
GuessingNo sources citedStop, research properly
Outdated infoOld articles, deprecated adviceCheck dates, find current sources
One world biasOnly looking at one sideDeliberately check the other world

Relationship to Other Skills

SkillFocus
goal-clarity-150WHAT we need to know
research-deep-150WHERE to find answers (internal + external)
deep-think-150HOW to reason about findings
impact-map-150WHAT the findings affect

Session Log Entry (MANDATORY)

After completing this skill, write to

.sessions/SESSION_[date]-[name].md
:

### [HH:MM] Understand-Deep 150 Complete
**Topic:** <research topic>
**Sources:** <internal/external sources used>
**Key Findings:** <bullet points>
**Synthesis:** <combined insight>

Remember: Most questions need BOTH worlds. Internal context tells you "what we have and why". External knowledge tells you "what's possible and what others learned". Deep research combines both for complete understanding.