This file defines document structure, Markdown tiers, writing rules, and `verify-doc-budgets` ceilings. Use [dsh-doc-standards](../.agents/skills/dsh-doc-standards/SKILL.md) for placement and validation, and [dsh-prose-standard](../.agents/skills/dsh-prose-standard/SKILL.md) for required coverage and editorial judgment; the [doc-tiers Agent Note](../.agents/notes/implemented/process/2026-07-04-doc-tiers-and-budgets.md) owns rationale.
## Document structure
These rules apply to human-facing documentation; [Agent Notes](../.agents/notes/README.md) remain outside their scope. A [postmortem](postmortem/README.md) is an incident-scoped reference; chronology records evidence, not a teaching sequence. A document's subject and tree position fix its scope: describe its own subject at appropriate detail, describe direct children only by purpose, responsibility, and high-level behavior, and link to the owning descendant for lower-level detail. Document type does not widen that scope. A reference may be exhaustive only about its own subject. Testing mechanisms, fixtures, and harnesses belong at the lowest owning level; higher documents link there.
Classify every in-scope document as a tutorial or reference. A tutorial follows an ordered path to an outcome and introduces only what each step needs. A reference defines a lookup scope and describes current behavior without depending on a teaching sequence. Separate substantial tutorial and reference content; use a clear structural boundary when either part is small.
Before writing a tutorial, privately classify the reader's starting knowledge and each concept as beginner, intermediate, or advanced. Establish prerequisites before dependent concepts, increase difficulty gradually, and move unnecessary advanced material to a later tutorial or reference.
Author in this order: locate the document in the tree; set its permitted detail; choose tutorial or reference; for a tutorial, order concepts by prerequisite and difficulty; relocate descendant-owned detail; replace lower-level explanations with links to their owners.
| Root `AGENTS.md` | Standing orders: rules an agent needs in context in every session, one to three lines each, linking its home | Stories, worked examples, situational procedures, anything restated from a linked home |
| [core-data-structures/](core-data-structures/core.md) | The type catalog: literal shapes and semantics of the spine and seam vocabulary | Behavior narration (→ architecture.md) |
| [Agent Notes](../.agents/notes/README.md) | Decision records under their own lifecycle contract | Migration plans, checklists, and spec-speak once implemented; archived notes are frozen history |
| [user/](user/index.md) | Product-facing guides published by the documentation website | Generated reference tables, contributor procedures, decision history |
- **Document current state, not change history.** Avoid "previously/now/no longer", PRs, commits, and stack positions in durable prose; name the live mechanism. Put change stories in commits, PRs, Agent Notes, or postmortems.
- **Every non-trivial change includes at least one Agent Note in the same PR.** Update the owning note or add one; only mechanical/local edits are exempt ([scope](../.agents/notes/README.md#when-to-write-one)).
- **One physical line per paragraph** (`verify-md-wrap`): use editor soft-wrap. Code blocks, tables, and list structure keep their formatting; code comments stay under the linter's column limit.
- **Fenced `ts` blocks must compile** (`doc-typecheck`); a pasted type declaration and its original JSDoc use ` ```ts type-equiv `, while a body-stripped public class declaration uses ` ```ts public-api `; register either in the manifest so neither can drift ([mechanics](development.md#documenting-types-verbatim-ts-type-equiv)).
- **The [core-data-structures catalog](core-data-structures/core.md) updates in the same change** that reshapes a documented type. `verify-type-equiv` catches drifted pastes, not never-documented new types ([what counts as core](core-data-structures/core.md#what-counts-as-core)).
- **Bilingual pairs update together**: editing either side obligates the counterpart and a re-record in the same change ([i18n contract](i18n/README.md)).
- **Comments and JSDoc state complete contracts, not reasoning transcripts.** Preserve behavior, timing, modality, exceptions, consequences, and non-obvious orientation; delete narration, test walkthroughs, review analysis, and code restatement. Keep the local contract and link its rationale. Use [dsh-prose-standard](../.agents/skills/dsh-prose-standard/SKILL.md) for details.
- Your audience is professional programmers. Prefer concise and straight-forward English over metaphor. Do not overuse words like "gate", "vocabulary", "surface", "seams".
Ceilings are guardrails, not reduction targets. At or below target, retain at least 5% headroom; above target, freeze the ceiling until relocation or condensation brings the document under target. Lower a ceiling only when the contract still has room, and raise it when content would otherwise be deleted. Targets: root `AGENTS.md` ≤ 1,600 words; `architecture.md` ≤ 1,800; subtree `AGENTS.md` ≤ 600, except `packages/AGENTS.md` ≤ 650 and this file ≤ 1,250; `packages/README.md` ≤ 600. Review governs unbudgeted tiers.
- Narrated history or war stories: "previously", "now", "no longer", "used to", "renamed", "was moved", PRs, or commits. State the current fact; link an Agent Note or postmortem when needed.
- Reasoning transcripts: step-by-step implementation narration, proof of obvious branches, test walkthroughs, or rejected local alternatives. Keep the resulting contract or durable rationale; delete the path used to derive it.
- Spec-speak in `implemented/` Agent Notes: "should", migration plans, acceptance checklists. An implemented Agent Note describes what is, per the [implemented-note instructions](../.agents/notes/implemented/AGENTS.md).
Link repository references with relative Markdown paths, never bare filenames or Agent Note numbers. `verify-md-links` catches missing targets; the [cross-link Agent Note](../.agents/notes/implemented/process/2026-06-18-markdown-cross-link-lint.md) owns the rationale.
