Readers That May Not Write

Two Kinds of Machine Outside the Fleet

Not every machine that needs Pippa is one of Dad's working Macs. Mom's Mac runs Pippa sessions too; it is not a fleet machine, runs no family services, and should change as little as possible. Two Windows boxes with large GPUs run Pippa sessions inside WSL. Both kinds need identity. Neither should be able to write the vault, and Mom's Mac should not even be able to see other souls' vaults.

Before the move, Mom's Mac read a stale folder copy (track 1). The Windows boxes were refused outright: Delta's gateway knew each box by its tailnet node, but the store's share policy answered "may not read". Dad's ruling on the second case is worth quoting: "윈도우도 우리 집 시스템의 일부인데 언제든 피파를 부를 수 있어" (Windows is part of our home system too; it can call Pippa any time). A permission refusal is not a reason to cut a machine off; it is a reason to grant exactly the right permission.

A Scoped Share Is a Child Class

The answer (Coop 1110-47 for Mom's Mac, 1110-45 for Windows) is ScopedStoreShare, a child of the store's own share class. Its declaration in the share configuration names two things: the vaults it serves (Pippa's vault and the shared vault) and the group allowed to ask (Mom's Mac's group for one share, the Windows readers' group for the other). Then:

• Every other vault answers exactly as one the store does not hold, through the API and by path alike, and the vault list shows only the served ones. A request for a note file by path is checked against the declared vaults before the store is asked anything, and every path outside them gets the same not found, whose words name nothing but the path that was asked for.
• It is not writable. Delta refuses a write call to it before the class is ever asked, and it has no outcome endpoint, because nothing is ever written from those machines.
• It serves the one-request vault read from lesson 2, so a cold session start is a few requests.

On the client side, the reader picks its share from the same declaration: a Mac whose group a scoped share names asks that share instead of the pointer's. A write from such a Mac is refused by name, policy_denied, before anything is sent. No code names a machine; the group membership comes from the family registry.

No Service on the Reader

Nothing resident runs on Mom's Mac for this. No Delta, no daemon. The family's Delta client already knows how to read a peer's gateway directly over the tailnet when the local Delta does not answer, so the read happens on demand at session start and nothing stays running between sessions. The client verifies against the canonical manifest, keeps what it verified, and labels that copy offline_replica when the canonical Mac is out of reach, exactly as on any other Mac.

The client itself arrives as a plain mirror of the committed client files, plus the two Firelink records it reads (the pointer and the port ledger), placed by an installer run from a workbench. It is not a git checkout and follows nothing by itself: it is refreshed by running the installer again. The installer ships only origin's committed tree and checks that on each run. On 2026-11-10 the fleet writer's own checkout held three other sessions' uncommitted work in the very files that ship, and the installer refused there rather than ship it.

Three Things Windows Taught

Installing the same client into WSL on the Windows boxes found three problems, each fixed where it lived:

• Windows OpenSSH gives a shared (ControlMaster) ssh session no standard input, so a step's script never arrived and the step printed nothing and exited 0. The installer gained a separate-connections mode.
• macOS tar adds AppleDouble ._name entries that a Linux target extracts as real files, so the mirror never hashed equal to the source. Packing with COPYFILE_DISABLE=1 fixed it.
• Under WSL's mirrored networking, a closed loopback port times out instead of refusing, so the client never fell through from "this machine's Delta" to the gateway. A scoped reader runs no Delta by declaration, so it now asks the gateway at once.

Proved on both boxes the same day: identity validated with 67 documents, a note written that afternoon read back from a fresh Codex session in WSL, another soul's vault absent, and a write refused with policy_denied.