contract: vendor the machine-snapshot checksum manifest and assert it here too (#208) - #210
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… here too (#208) contracts/machine_snapshot/ is vendored verbatim in TWO repos -- FactoryLM (producer) and MIRA (consumer) -- and MIRA PRD #3048 calls it the compatibility boundary both projects must test the exact same payload against. A checksum guard on ONE side does not protect a boundary. The failure mode is a one-sided edit, and the repo that edits its own copy keeps passing against it; neither goes red. MIRA added CHECKSUMS.sha256 + an integrity test in #3060, so until now the guard covered MIRA only. CHECKSUMS.sha256 is vendored byte-identical from MIRA. All six fixtures were verified byte-identical across both repos before vendoring, so this passes with no fixture changes. ALSO -- and this is what would have made the guard useless: the workflow's paths filter was services/plc-modbus/** only, so a PR editing ONLY a file under contracts/machine_snapshot/ never triggered the job. That is precisely the one-sided edit the guard exists to catch; it would have sat silent for its own purpose. contracts/machine_snapshot/** added. Proven by execution: 8 pass -> append a newline to snapshot_v1_valid.json -> the checksum test fails with the regeneration instructions -> restore -> 212 passed (204 on main + 8 new).
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Closes #208.
contracts/machine_snapshot/is vendored verbatim in two repositories — FactoryLM (producer) and MIRA (consumer) — and MIRA PRD #3048 calls it "the compatibility boundary between repositories; both projects must test against the exact same payload."A checksum guard on one side does not protect a boundary. The failure mode is a one-sided edit, and the repo that edits its own copy keeps passing against it — neither goes red. MIRA added
CHECKSUMS.sha256+ an integrity test in #3060, so until now the guard covered MIRA only.CHECKSUMS.sha256is vendored byte-identical from MIRA. All six fixtures were verified byte-identical across both repos immediately before vendoring, so this passes with no fixture changes.The part that would have made the guard useless
The workflow's paths filter was
services/plc-modbus/**only. A PR editing only a file undercontracts/machine_snapshot/never triggered the job — which is exactly the one-sided edit the guard exists to catch. It would have sat silent for its own purpose.contracts/machine_snapshot/**added to the filter, with a comment saying why so nobody prunes it later as noise.Evidence
Proven by execution, not asserted:
The guard also asserts every fixture on disk is listed, so a new unguarded fixture can't slip in behind a green check.
Note on the mechanism
Checksums detect drift; they don't prevent two copies existing. #208's step 2 — a real shared source (single-source + CI sync check, submodule/subtree, or a published contract package) — is still open and deliberately not attempted here. This is the floor, not the destination.