An unannotated param resolving to a plausible .s64 was the classic
silent-default trap (root of the 2.5 multi-param-closure bug). Replace it
with a dedicated TypeId.unresolved at slot 0, so a zero-initialised or
forgotten TypeId trips the sentinel instead of masquerading as a real type.
- types.zig: TypeId.unresolved = 0 (void moves to 17); TypeInfo.unresolved;
sizeOf/toLLVMType @panic on it (codegen tripwire); hash/eql/printer cover it.
- type_bridge: inferred_type => .unresolved (was .s64).
- resolveParamType: emit "parameter 'x' has no type annotation" for a
genuinely-unannotated value param (comptime/variadic/pack params exempt --
they resolve via per-call substitution).
- lowerLambda: resolve unannotated params from the target closure signature;
otherwise emit "cannot infer type of lambda parameter".
- CLAUDE.md: .void documented as an UNACCEPTABLE failed-type sentinel (it
conflates with a real, heavily-checked type); prescribe a distinct
.unresolved-style value + codegen tripwire.
Snapshot churn: one .ir (ffi-objc-call-06) -- the runtime type-name table and
typeof match arms renumber by the new builtin slot; program output unchanged.
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