Repository navigation
Prompt Size
The prompt slice sends one tailored text for the lean_body section.
This page gives its measured size and the one part it cannot change.
The rules in the text are on Prompt.
| Measure | Value |
|---|---|
| Sections | 8: intro, doing_tasks, system, blocks, verification, actions, tools, counts
|
| Source texts | 6,794 bytes and 1,314 words in the 8 files |
Sent text (LEAN_BODY) |
7,515 bytes and 1,441 words, with the section tags |
| Largest file |
doing-tasks.md, 3,289 bytes |
| Date | 2026-10-19 |
The source texts are the 8 files in src/plugins/claudetto/slices/prompt/prompts/.
wc -c and wc -w measure them before the section tags.
LEAN_BODY is exported by domain/lean-body.ts, and Bun 1.4.3 measured it after the build.
It has only ASCII characters, so its bytes and characters are equal.
The sections are counted in LEAN_BODY, which has eight <tag> lines.
The stock lean_body text of Claude Code 2.1.302 is in tests/claudetto/prompt/fixtures/lean_body.txt.
It is 616 bytes, which is 612 characters, and 99 words.
The net growth is about 6,900 bytes.
These token counts are estimates, not counts from a tokenizer:
about 1.9k tokens for LEAN_BODY, about 150 tokens for the stock text, and about 1.7k tokens of growth.
The repository has no bound on this size.
Claude Code 2.1.302 and 2.1.303 build the shared lean_body section without a prompt.section call.
So a prompt.section hook never sees that section.
The prompt.compose hook of the prompt slice replaces its text with LEAN_BODY, and it keeps the other sections in their place.
Until this fix, LEAN_BODY never reached the model.
The evidence is the prompt_snapshot attachment in the transcripts of the eval runs on 2026-10-19.
It showed the stock # Harness text, and the <actions> text was absent.
The sizes on this page come from the source files and from the built module. They do not come from a request that the model received. The live size comes with the eval reruns, and this page does not state one before then.
The prompt.compose and prompt.section hooks change the system prompt.
They cannot change the compact prompt of Claude Code.
So the handoff slice replaces the built-in compaction by default (Handoff).
The context_management section follows the compaction state of the session (Prompt).
With the state built-in, the compact prompt stays unchanged.
The snippet does not set DISABLE_COMPACT (Settings Snippet).
claudetto
- Start
- Slices
- Add-Ons
- Reference
- Rationale
- Evidence
- Development
Claude Code