Insight Extraction Skill

Overview

Analyze completed coding sessions and extract structured learnings for the memory system. Insights help future sessions avoid mistakes, follow established patterns, and understand the codebase faster.

Core principle: Extract ACTIONABLE knowledge, not logs. Every insight should help a future session do something better.

When to Use

Always:

• After completing a coding task
• After fixing bugs
• After discovering new patterns
• After failed attempts (especially valuable)

Exceptions:

• Trivial changes with no learnings
• Documentation-only changes

The Iron Law

NO SESSION END WITHOUT INSIGHT EXTRACTION FOR NON-TRIVIAL WORK

Non-trivial sessions should capture learnings before context is lost.

Input Required

To extract insights, you need:

1. Git diff - What files changed and how
2. Task description - What was being implemented
3. Attempt history - Previous tries (if any), what approaches were used
4. Session outcome - Success or failure

Workflow

Phase 1: Gather Session Data

# Get the diff of changes
git diff HEAD~1 --stat
git diff HEAD~1

# Get commit message
git log -1 --pretty=format:"%s%n%n%b"

# Get list of modified files
git diff HEAD~1 --name-only

Phase 2: Analyze File Insights

For each modified file, extract:

• Purpose: What role does this file play?
• Changes made: What was the modification? Focus on the "why" not just "what"
• Patterns used: What coding patterns were applied?
• Gotchas: Any file-specific traps?

Good example:

{
  "path": "src/stores/terminal-store.ts",
  "purpose": "Zustand store managing terminal session state with immer middleware",
  "changes_made": "Added setAssociatedTask action to link terminals with tasks",
  "patterns_used": ["Zustand action pattern", "immer state mutation"],
  "gotchas": ["State changes must go through actions, not direct mutation"]
}

Bad example (too vague):

{
  "path": "src/stores/terminal-store.ts",
  "purpose": "A store file",
  "changes_made": "Added some code",
  "patterns_used": [],
  "gotchas": []
}

Phase 3: Extract Patterns

Only extract patterns that are reusable:

• Must apply to more than just this one case
• Include where/when to apply the pattern
• Reference a concrete example in the codebase

Good example:

{
  "pattern": "Use e.stopPropagation() on interactive elements inside containers with onClick handlers",
  "applies_to": "Any clickable element nested inside a parent with click handling",
  "example": "Terminal.tsx header - dropdown needs stopPropagation to prevent focus stealing"
}

Phase 4: Document Gotchas

Must be specific and actionable:

• Include what triggers the problem
• Include how to solve or prevent it
• Avoid generic advice ("be careful with X")

Good example:

{
  "gotcha": "Terminal header onClick steals focus from child interactive elements",
  "trigger": "Adding buttons/dropdowns to Terminal header without stopPropagation",
  "solution": "Call e.stopPropagation() in onClick handlers of child elements"
}

Phase 5: Document Approach Outcome

Capture the learning from success or failure:

• If succeeded: What made this approach work? What was key?
• If failed: Why did it fail? What would have worked instead?
• Alternatives tried: What other approaches were attempted?

This helps future sessions learn from past attempts.

Phase 6: Generate Recommendations

Specific, actionable advice for future work:

• Must be implementable by a future session
• Should be specific to this codebase, not generic
• Focus on what's next or what to watch out for

Good: "When adding more controls to Terminal header, follow the dropdown pattern in this session - use stopPropagation and position relative to header"

Bad: "Write good code" or "Test thoroughly"

Phase 7: Output Structured Insights

Create the structured insight output:

# Session Insights: [Task Name]

## Date

[timestamp]

## Task

[Description of what was being implemented]

## Outcome

[SUCCESS/FAILURE]

## File Insights

### [file-path]

- **Purpose**: [what this file does]
- **Changes**: [what was changed and why]
- **Patterns**: [patterns used]
- **Gotchas**: [things to watch out for]

## Patterns Discovered

### [Pattern Name]

- **Pattern**: [description]
- **Applies to**: [when to use]
- **Example**: [file or code reference]

## Gotchas Discovered

### [Gotcha Name]

- **Issue**: [what to avoid]
- **Trigger**: [what causes it]
- **Solution**: [how to handle]

## Approach Analysis

### What Worked

[Description of successful approach]

### What Failed (if applicable)

[Description of failed approaches and why]

### Alternatives Tried

[List of other approaches attempted]

## Recommendations for Future Sessions

1. [Specific recommendation 1]
2. [Specific recommendation 2]

Save to .claude/context/memory/learnings.md (append).

Handling Edge Cases

Empty or Minimal Diff

If the diff is very small or empty:

• Still extract file purposes if you can infer them
• Note that the session made minimal changes
• Focus on recommendations for next steps

Failed Session

If the session failed:

• Focus on why it failed - this is the most valuable insight
• Extract what was learned from the failure
• Recommendations should address how to succeed next time

Multiple Files Changed

• Prioritize the most important 3-5 files
• Skip boilerplate changes (package-lock.json, etc.)
• Focus on files central to the feature

Verification Checklist

Before completing insight extraction:

• Git diff analyzed
• File insights extracted for key files
• Reusable patterns documented
• Gotchas documented with triggers and solutions
• Approach outcome documented
• Recommendations are specific and actionable
• Insights saved to memory file

Common Mistakes

Too Vague

Why it's wrong: "Fixed the bug" helps no one.

Do this instead: "Fixed race condition in useEffect by adding cleanup function. Pattern: always return cleanup from async effects."

Generic Advice

Why it's wrong: "Test your code" is not actionable.

Do this instead: "Run npm test src/stores after changing store logic - the tests catch state management bugs."

Missing Context

Why it's wrong: Future sessions won't understand why.

Do this instead: Include file paths, function names, and specific scenarios.

Integration with Other Skills

This skill works well with:

• session-handoff: Use insights in handoff documents
• summarize-changes: Complement change summaries with insights
• debugging: Extract insights from debugging sessions

Iron Laws

1. ALWAYS extract insights immediately after task completion — delayed extraction loses context; the "what" can be reconstructed but the "why" evaporates within the session.
2. NEVER record what was done — only record what was learned; activity logs belong in task metadata, not in the learning system.
3. ALWAYS check for duplicate insights before writing — appending a near-duplicate insight pollutes the memory index and degrades future retrieval quality.
4. NEVER write vague insights like "X is good" without concrete context, file path, or example — vague insights are unfindable and unhelpful to future sessions.
5. ALWAYS tag insights with domain category ([CODE], [WORKFLOW], [SECURITY], etc.) — untagged insights are effectively invisible to agents searching by domain.

Anti-Patterns

Anti-Pattern	Why It Fails	Correct Approach
Recording activity ("implemented auth") instead of learnings	Agents can reconstruct history from git; they cannot reconstruct tacit knowledge	Record "why" and "gotcha": "Fiber's CSRF middleware must be before route registration, not after"
Skipping deduplication check	Duplicate entries inflate memory size and confuse retrieval	grep -i "keyword" learnings.md before appending; update existing entry if found
Vague insights without file/function context	Future sessions can't locate or apply the insight	Include concrete path: "In .claude/hooks/routing/routing-guard.cjs line 47: exit 0 on parse error"
Extracting only at session end	Long sessions lose early context; critical gotchas forgotten	Extract after each significant task completion, not just at session boundary
Storing insights only in task metadata	Task metadata is not read by future sessions or agents	Always write to .claude/context/memory/learnings.md with tagged format

Memory Protocol

Before starting: Read .claude/context/memory/learnings.md

After completing:

• New pattern -> .claude/context/memory/learnings.md
• Issue found -> .claude/context/memory/issues.md
• Decision made -> .claude/context/memory/decisions.md

ASSUME INTERRUPTION: If it's not in memory, it didn't happen.