# Compact Boundary Session Distillation

> Distill the compact boundary delta into the session memory summary and the freshest user cues needed for skill capture prompts.

- Skill: `vishuwa2004/compact-boundary-session-distillation` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add vishuwa2004/compact-boundary-session-distillation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/vishuwa2004/compact-boundary-session-distillation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: vishuwa2004 (https://skillmd.com/u/vishuwa2004)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/vishuwa2004/compact-boundary-session-distillation

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# SKILL: Compact Boundary Session Distillation
**Domain:** context-management  
**Trigger:** When skillify captures a repeating process, use the latest session memory and the user messages after the most recent compact boundary so the prompt only contains the current instructions.
**Source Pattern:** Distilled from reviewed context, compaction, and memory-governance patterns.

## Core Method
- Call `getSessionMemoryContent()` to fill the `<session_memory>` block; the helper already returns `null` when no file exists so the prompt displays `No session memory available.` instead of throwing.
- Slice the transcript with `getMessagesAfterCompactBoundary(context.messages)` from `runtime/utils/messages.ts`, which locates the last compact boundary and optionally projects out snipped history via `projectSnippedView` when `HISTORY_SNIP` is on.
- Feed that clip into `extractUserMessages`, which keeps only `type === 'user'` entries, flattens mixed content blocks into strings, trims blank text, and yields the freshest user steering cues.
- Replace `{{sessionMemory}}`, `{{userMessages}}`, and the optional `{{userDescriptionBlock}}` inside `SKILLIFY_PROMPT` so the kernel prompt knows which context to expose to the skill authoring assistant.

## Key Rules
- Do not let user text from before the compact boundary slip into the distilled user stanza; the `getMessagesAfterCompactBoundary` call enforces that slice.
- Always wrap the memory summary in `<session_memory>` and the user messages in `<user_messages>` so downstream tooling can parse them reproducibly.
- Respect the description the user optionally supplied, because it seeds the suggested skill name, goals, and trigger phrases in the AskUserQuestion rounds that follow.

## Example Application
When the user redirects the conversation toward automation mid-session, this pattern yields a short prompt that highlights the current process and memory highlights without dragging the whole transcript along.

## Anti-Patterns (What NOT to do)
- Do not include assistant or system messages—even if they appear in the slice—since only the user's intent should feed into the new skill definition.
- Do not drop the session memory block; even if it resolves to `null`, the placeholder text keeps the prompt structure stable for downstream parsers.