Chat Compactor

Generate structured summaries optimized for AI agent continuity across sessions.

Why This Exists

Human-written summaries and ad-hoc AI summaries lose critical context:

• Decision rationale gets lost (why X, not Y)

• Dead ends get forgotten (agent re-tries failed approaches)

• Implicit knowledge isn't captured (file locations, naming conventions, gotchas)

• State is unclear (what's done, what's pending, what's blocked)

This skill produces agent-optimized handoff documents that prime the next session.

Output Format

Generate a markdown file with this structure:

Session: [Brief Title]

Date: [YYYY-MM-DD] Duration: ~[X] messages

Context Snapshot

[1-2 sentences: What project/task, what state it's in right now]

What Was Accomplished

• [Concrete outcome 1]
• [Concrete outcome 2]

Key Decisions & Rationale

Current State

• Working: [files/features that are functional]
• Broken/Blocked: [what's not working and why]
• Modified files: [list with brief note on changes]

Dead Ends (Don't Retry)

• ❌ [Approach that failed] — [why it failed]

Next Steps (Prioritized)

1. [Most important next action]
2. [Second priority]

Environment & Gotchas

• [Any setup notes, versions, quirks discovered]

Key Code/Commands Reference

[Only if there are non-obvious commands or snippets the next session needs]

Workflow

• Scan conversation for: decisions, outcomes, failures, file changes, blockers

• Identify the "handoff moment" — what would a fresh agent need to continue?

• Generate structured summary using format above

• Save to file: session-[topic]-[date].md in project root or /home/claude/sessions/

Compaction Triggers

Invoke this skill when:

• User says: "compact", "wrap up", "save session", "summarize for next time"

• Context window exceeds ~50% capacity and task is ongoing

• Before major context switches

• End of debugging/implementation session

Quality Criteria

Good compactions are:

• Scannable: Next agent gets orientation in <30 seconds

• Actionable: Clear next steps, not vague summaries

• Defensive: Dead ends documented to prevent re-exploration

• Minimal: No fluff, every line earns its tokens

Anti-Patterns

Avoid:

• Narrative prose ("First we tried X, then Y, then Z...")

• Redundant context (don't repeat what's in code comments)

• Vague summaries ("Made good progress on the feature")

• Missing failure documentation (most valuable part!)

Example Trigger & Response

User: "Let's wrap up, compact this session"

Agent:

• Reviews conversation for key decisions, outcomes, failures

• Generates structured markdown per format above

• Saves to session-[topic]-[date].md

• Confirms: "Session compacted to session-auth-refactor-2025-01-06.md — ready for next time."