I3955 — Whether an archived cargo build directory is reused on a second node is measured before anything restores one

✕BLOKOVÁNO vlna 0 · p1 · profil implementation · bezpečné paralelně

Part of builds-reuse-the-mesh-cache — Builds reuse the mesh cache: compiled Rust, the cargo build directory, mix deps and npm packages, keyed by platform, toolchain and inputs.

Cíl

Build one commit cold on node A, archive its build directory without incremental state, restore it on node B with the same paths but its own checkout and registry, and record how many units B finds Fresh, the archive size and both build times; decide from that whether the cargo build directory becomes a kind of mesh build-cache ensure.

Proč

The owner, 2026-10-22, after lundra (the build and deploy host) reached zero free bytes: the shared cache must be part of Majordomus — used when MinIO is available, enforced, dynamic, derived — for compiled Rust, the shared cargo build directory, mix deps.get and npm install, keyed by a triplet for the most reuse. Decided the same day after critique: the store is trusted only through a signed offer (I2671), the build directory archive is measured before it is built (I3955), and the dependency cache is generic and wired first into prismatic-platform. See ADR 0157 and intent a-build-reuses-what-the-mesh-already-built.

Aktuální stav

Not measured. ADR 0139 measured 0 sccache hits between two build directories; the build-script fingerprint carries each tree's absolute root on purpose (.cargo/config.toml, MAJORDOMUS_BUILD_TREE); build directories ran from 3.4 GB median to 25 GB (lib/rust_bin.sh).

Cílový stav

A recorded claim with the commit, the machines, the counts and the times, and the decision it supports written into ADR 0157. Measured 2026-10-22 on lundra in two containers of rust:1-bookworm with identical paths and separate checkouts and registries (3 cpus each): commit 2034d4a3f0b cold on A in 566 s (142 units compiled), build directory archived without incremental state at 2.9 GB, restored on B: 142 Fresh, 0 compiled. Decision 12 of ADR 0157 records it: the cargo build directory is a kind of I3952.

Rozsah

• .ai/repo/adrs/0157-the-mesh-offers-a-shared-build-cache.md
• .ai/repo/project/intents/a-build-reuses-what-the-mesh-already-built.yaml
• docs/BUILD_CACHE.md

Mimo rozsah

• Building the restore itself

Závislosti

Žádné. Tento úkol je kořenem grafu.

Kritéria přijetí

• Node B's checkout and registry are its own (new mtimes), and only the build directory travels
• The result is recorded whichever way it falls; a reuse below the cost of the transfer decides against the kind

Validace

• bin/majordomus plan validate

Požadované důkazy

• build_dir_reuse_measured

Důkazy

Nic nezaznamenáno. Za každým tokenem výše musí stát příkaz nebo artefakt, než lze tento úkol dokončit; vyprávění se odmítá.

Časová osa

zahájeno

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ověřeno

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dokončeno

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Tato tři pole, důkazy výše a stav závislostí jsou vše, z čeho se stav skládá. Neexistuje žádné pole stavu, které by s nimi mohlo být v rozporu.

Canonical record: .ai/repo/project/issues/I3955.yaml. Read it back with majordomus plan show I3955.