---
id: "0032"
date: 2026-07-13
status: Accepted
supersedes:
superseded-by:
affected-paths: [docs/implementation-status.md, docs/implementation-status/, plugins/os-doc-hygiene/scripts/scanner.py, CLAUDE.md]
affected-components: [docs, os-doc-hygiene]
---

# 0032 — AI-maintained knowledge files are indexes with progressive disclosure

## Context

AI-read markdown files grow unbounded when maintained append-only: docs/implementation-status.md reached 729 lines (~9k estimated tokens) and was read routinely at main-loop rates, paying the full context cost on every read even when only one component's status was needed. The os-doc-hygiene scanner gained a deterministic `file_length` signal (2026-07-13, issue #25 part 1; defaults 400 lines / 4000 estimated tokens) that now flags every oversized doc, but a signal without a target structure only reports the problem. The same growth pattern threatens CLAUDE.md and any other file the AI is instructed to keep current.

## Decision

AI-maintained knowledge files are **indexes with progressive disclosure**: the main file holds only headline entries and one-liners with pointers; full detail lives in leaf files (e.g. `docs/implementation-status/<component>.md`) read on demand. Detail that merely restates a decision already recorded in `docs/adr/` is removed, not moved — the ADR is the durable record. Operational runbooks referenced from CLAUDE.md land in a stable leaf file (`docs/implementation-status/operational-procedures.md`), never silently dropped. The os-doc-hygiene `file_length` signal (400 lines / ~4k tokens) is the enforcement mechanism: a flagged AI-maintained file is distilled back to index form rather than left to grow. Applied first to docs/implementation-status.md (2026-07-13); applies later to CLAUDE.md cleanup (see the os-context prompt-files card).

## Consequences

Easier: routine reads cost one small index instead of the whole history; per-component detail is fetched only when working on that component; the length signal makes drift objective and cheap to catch; ADRs stop being duplicated in prose. Harder: recording a completed step now touches two files (one-line index entry + leaf detail); cross-file links must be kept unbroken (a link-integrity pass belongs to any restructure); readers must follow a pointer for depth instead of scrolling one file.

## Alternatives rejected

1) Keep append-only files and rely on the classifier's bloat/distill/split taxonomy downstream — rejected: oversized files were only caught if some other signal fired, and by then the context cost had already been paid for weeks. 2) Periodic manual pruning of the monolith with no structural convention — rejected: pruning decisions are re-litigated every time and history gets lost inconsistently; an index+leaf structure makes the "where does this go" decision mechanical. 3) Move stale sections into leaf files too (archive everything) — rejected: detail already recorded in an ADR is duplication; the ADR system exists to be the durable decision record.
