feat(igla): Wave Loop 893 — module-scope [605][2]^6 Pt non-power-of-two outer-dimension array-of-struct variable from call with indexed signed writes #1848

Next mechanical step in the packed-vector array-of-struct ladder.

• Outer dimension: 605 (non-power-of-two)
• Inner struct: [2]^6 Pt (384 bits per element)
• Total elements: 605 × 64 = 38,720
• Packed vector width: 38,720 × 32 = 1,239,040 bits (~1.182 MiBit)

Pattern: module-scope variable initialized from a pure function call, mutated via signed-index field writes, read back with assert_eq inside a bench block.

Expected zero compiler / FROZEN_HASH changes.

🤖 Generated with Claude Code

User Scenarios

• Given a module-scope variable of outer dimension 605 (non-power-of-two) with inner struct [2]^6 Pt (384 bits per element), When the variable is initialized from a pure function call and mutated via signed-index field writes, Then reading it back with assert_eq inside a bench block passes without compiler or FROZEN_HASH changes.

Requirements

• FR-001: The compiler MUST accept a module-scope array-of-struct variable with outer dimension 605 and inner dimension [2]^6 Pt.
• FR-002: The compiler MUST support initialization of such a variable from a pure function call.
• FR-003: The compiler MUST allow signed-index field writes to mutate the variable.
• FR-004: The compiler MUST verify assert_eq reads inside a bench block against the mutated state.
• FR-005: The compilation and verification MUST produce zero changes to compiler behavior or FROZEN_HASH.

Success Criteria

• t27c specs/tools/tri/loop.t27 compiles and verifies with exit 0
• t27c specs/memory/graph/scope.t27 compiles and verifies with exit 0
• t27c specs/tri/collections/array.t27 compiles and verifies with exit 0
• FROZEN_HASH remains unchanged after running the above commands

Boundary

• specs/tools/tri/loop.t27
• specs/memory/graph/scope.t27
• specs/tri/collections/array.t27