Architecture

Ports-and-adapters over a flat crates/ workspace: myco-core is pure domain — item models, the id registry, the state machine — with no I/O. Ports are traits (myco-store, myco-config, myco-index); impls live in separate crates; crates/myco-cli (package myco) is the composition root that wires impls to verbs.

Design rules:

• No unsafe, no async — the binary stays dependency-light and synchronous; no runtime to embed.
• Git via the git CLI — myco-git shells out for the orphan branch, worktree, and per-verb commits; no libgit2/gix binding.
• Markdown is the file spec — myco-store-md owns strict parse/emit: deterministic output, stable ordering, minimal diffs. myco-testkit freezes emit with golden fixtures and proptest round-trips, so the format can't drift silently.
• The index is derived, never canonical — myco-index-redb snapshots ledgers into redb for status/board/org; it can be deleted and rebuilt at any time.

crate	layer	purpose
myco-core	domain	myco domain core: item models, ID registry, state machine — pure, no I/O
myco-config	port	Config port: where myco.toml-shaped config comes from
myco-index	port	Index port: the derived, disposable cache powering status/board/report/org views
myco-store	port	Store port: where project/ state (TODO.md, BACKLOG.md, meta.toml, item files) is persisted
myco-ops	ops	myco — ops I/O shell: project discovery, store open/save, commit-per-mutation, verb plumbing
myco-config-toml	adapter	Config impl: myco.toml file (explicit path, env, ./, ~/.config)
myco-git	adapter	Git plumbing for myco — shells out to the git CLI; owns the project branch/worktree mechanics
myco-index-redb	adapter	Index impl: redb snapshots + repos.toml registry under ~/.local/share/myco (disposable derived cache)
myco-shell	adapter	Run a command in a working directory via bash -c — the generic shell-out helper
myco-store-md	adapter	Markdown adapter for the store port — strict parse/emit of project/ files, round-trip stable; owns the file spec
myco-testkit	adapter	Golden fixtures + conformance: frozen md emit snapshots and proptest round-trips for the project/ file spec
myco-tui	adapter	myco — interactive board TUI (ratatui); a thin front-end over myco-ops
myco	binary	myco — project management, grown not built: agent-first PM CLI

Boundary — work memory only

myco owns the ledger of intent (tasks, issues, proposals, plans, ADRs, handoffs). Neighbors own their own memory:

• sturn — ephemeral coordination (live claims/ops/topics)
• kuda — code memory; myco indexes work items, not code
• peregrin — orchestration; an optional myco serve ndjson wire is deferred per adrs/0001
• bupha — CI gate; myco check in pipelines, Item: trailers
• mycena — surfaces TODO/FIXME in code → myco absorb
• sepia — session lifecycle → myco handoff / myco resume

Anything needing a daemon, a multi-machine view, or arbitration between actors belongs to peregrin, not here.