GO_SRC_SHA256 was wrong since it was first pinned in Task 1 — this path had never actually been exercised in any prior CI run or local test because every earlier failure happened before reaching the Go install step, or (once it did run) nothing had checked the pinned value against go.dev's own published checksum yet. Task 88's log caught it: the real go1.26.5 linux-amd64 tarball hashes to 5c2c3b16caefa1d968a94c1daca04a7ca301a496d9b086e17ad77bb81393f053 (cross-checked against https://go.dev/dl/?mode=json directly), not the previously pinned value. Also independently re-verified LIBSECCOMP_SRC_SHA256 against the real v2.6.1 tarball while looking at this — that one was already correct. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>