Zig only runs tests in files the test root actually resolves. A re-export like `pub const Foo = @import("f.zig").Foo` never references the decl in a test build, so f.zig is never resolved: its tests do not run, and its function bodies are never analyzed, so even hard compile errors stay hidden. root.zig carried a hand-written list of files to pull in, and it rotted -- identity, oauth, jetstream, xrpc/transport and xrpc/xrpc all drifted out of it. That is how da77f87 was possible: oauth/client.zig had two compile errors sitting on main while CI reported green, and its 13 tests had never run. Completing the list takes the suite from 486 to 551. unreachedTestFiles() in build.zig now walks src/ and fails the test step with the exact import lines to paste, so the list cannot silently rot again. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>