Building tier 0 forced the question "the one binary installed by hand" had been carrying unexamined. A TypeScript host needs a runtime present before it runs, so the thing installed by hand becomes two — and the second must be installed by the means the host exists to replace. So the host is a statically linked binary that requires nothing present, written in Go. Rejected: a runtime installed first, which breaks the property the tier rests on; and bundling the runtime into the executable, which carries ninety megabytes to preserve a language choice and puts a young feature at the bottom of the stack. The argument that decided it is architectural rather than about taste. 0037 means the host never queries the mesh database and 0039 means it only receives declarations, so the host shares NO code with any other tier — not a client, not a schema, not the SDK. The language boundary falls exactly on a boundary that already exists, and a second language usually costs duplicated logic where here there is none to duplicate. §8 gains a scope: it said "TypeScript throughout" when everything was a service or a surface, and is now scoped to those with tier 0 named. Another sync owed. Playbook 04 steps 2 and 4: repos.md records mesh-host as existing, the design takes code: [mesh-host] and status: in-progress.
03-DESIGN
The authoritative specification. Implementation is built against what is written here.
Two layers
| Folder | What it is |
|---|---|
00-as-is/ |
The mesh that exists today. Shipped behaviour, described as it is — including behaviour nobody would choose again. |
01-to-be/ |
The mesh being built toward. Every statement traceable to a record in 02-DECISIONS/. |
They are never mixed. A statement about the future does not belong in an as-is document, and an as-is document is never edited to describe an intention.
When a to-be design ships, it does not move. Its as-is counterpart is written or updated,
the to-be document's status becomes implemented, and both stand — one describing what runs,
the other recording what was intended. Deleting the intention loses the reasoning, which is
the expensive half.
Frontmatter
Every design document (not the READMEs) carries:
---
layer: as-is | to-be
status: designed | in-progress | implemented | abandoned
code: [] # owning code repo(s), from 00-META/repos.md
updated: YYYY-MM-DD # date of the last status change, not of text edits
decisions: [] # 02-DECISIONS/ records this document rests on
---
For an as-is document, status: implemented is the normal state — it describes something that
runs — and code: names where that implementation lives.
Status changes when implementation state changes, never because design text was edited. An
implemented claim must be defensible from the owning repository's main branch, not from
intent. If it cannot be checked, it is in-progress.
Cross-cutting views are generated from this frontmatter by the hq-status skill and never
written to disk.
What belongs here
Functional analysis, architectural description, and specification — prose and diagrams
only, no code. A manifest field may be named; a manifest may not be pasted. A document
enters the to-be layer only after the decision behind it is recorded in 02-DECISIONS/
and the research that produced it is closed.
Subfolders are encouraged where a layer grows enough to need them.