---
url: >-
  https://adk.nht.io/api/@nhtio/adk/batteries/context/compact/summarizer/variables/COMPACTION_SYSTEM_PROMPT.md
description: >-
  The FAITHFUL Claude Code compaction schema — the 9 sections extracted VERBATIM
  from the flagship reference agent's own real auto-compactions (~4700-token
  structured summaries observed across 28 compactions in that agent's
  development session). Using the real prompt (not an invented one) is what
  makes this battery's evaluation honest: the compact strategy loses exactly the
  detail Claude Code's own compaction loses, no more and no less.
---

# Variable: COMPACTION\_SYSTEM\_PROMPT

```ts
const COMPACTION_SYSTEM_PROMPT: string;
```

Defined in: [src/batteries/context/compact/summarizer.ts:70](https://github.com/NHTIO/ADK/blob/v1.20260713.1/src/src/batteries/context/compact/summarizer.ts#L70)

The FAITHFUL Claude Code compaction schema — the 9 sections extracted VERBATIM from the flagship
reference agent's own real auto-compactions (~4700-token structured summaries observed across 28
compactions in that agent's development session). Using the real prompt (not an invented one) is
what makes this battery's evaluation honest: the compact strategy loses exactly the detail Claude
Code's own compaction loses, no more and no less.

## Remarks

The 9 sections: (1) Primary Request and Intent, (2) Key Technical Concepts, (3) Files and Code
Sections, (4) Errors and Fixes, (5) Problem Solving, (6) All User Messages, (7) Pending Tasks,
(8) Current Work, (9) Next Step. Callers may supply their own prompt via the `systemPrompt` option
on [assembleCompactedTurns](../functions/assembleCompactedTurns.md) (and [summariseTurns](../functions/summariseTurns.md) directly) — this default is a
calibrated starting point, not a hard requirement.