# PR-2.3 — Normalize Value Model (Stack vs Heap References)

### Briefing

The VM must use a clear value model: primitives and tuples on the stack, heap objects referenced through opaque handles. This PR prepares the VM for the GC-based heap.

### Target

* Define a single `Value` representation that distinguishes:

  * Immediate primitives.
  * Heap references (opaque handles).
* Remove any gate-based or borrow-based value types.

### Work items

* Review the `Value` or equivalent enum/struct.
* Remove variants related to gates, borrows, or HIP.
* Ensure only the following categories remain:

  * Primitives (int, bool, etc.).
  * Tuples or small aggregates.
  * Heap reference handle (placeholder for future GC objects).
* Update stack operations accordingly.

### Acceptance checklist

* [ ] `Value` type has no HIP/gate-related variants.
* [ ] All stack operations compile with the new value model.
* [ ] No borrow/mutate semantics remain.
* [ ] `cargo test` passes.

### Tests

* Existing tests only.

### Junie instructions

**You MAY:**

* Simplify the `Value` enum/struct.
* Remove legacy variants and adjust matches.

**You MUST NOT:**

* Design the GC handle layout.
* Introduce new object systems.
* Change instruction semantics beyond type cleanup.

**If unclear:**

* Ask what the intended value shape should be.

---

# PR-2.4 — Consolidate Trap and Error Surface

### Briefing

With HIP removed, the runtime trap surface must be simplified and aligned with the new stack+heap model.

### Target

* Define a minimal, coherent set of runtime traps.
* Remove traps that only existed for HIP/RC semantics.

### Work items

* Audit the VM’s trap/error enums.
* Remove HIP/RC-related traps.
* Keep only traps that remain meaningful, such as:

  * Illegal instruction.
  * Stack underflow/overflow.
  * Invalid jump target.
  * Out-of-bounds memory access.
* Ensure trap handling paths are consistent and deterministic.

### Acceptance checklist

* [ ] Trap enum contains only relevant traps.
* [ ] No HIP/RC trap names remain.
* [ ] VM compiles and tests pass.

### Tests

* Adjust any tests expecting removed trap codes.

### Junie instructions

**You MAY:**

* Delete unused trap variants.
* Refactor match statements accordingly.

**You MUST NOT:**

* Add new trap categories without approval.
* Change the meaning of existing non-legacy traps.

**If unclear:**

* Ask before modifying trap semantics.

---

# PR-2.5 — Prepare Call Frame Structure for Closures and Coroutines

### Briefing

Before introducing closures and coroutines, the call frame structure must be neutral and future-proof, without HIP-specific fields.

### Target

* Simplify the call frame to a minimal, generic structure.
* Remove any HIP/borrow/gate-related fields.

### Work items

* Review the call frame struct.
* Remove fields tied to scope frames, borrow state, or gates.
* Ensure the frame contains only:

  * Function identifier.
  * Program counter.
  * Base stack pointer.
  * Locals or register area (if applicable).
* Keep the structure simple and extensible.

### Acceptance checklist

* [ ] Call frame struct has no HIP-related fields.
* [ ] VM call/return paths compile and work.
* [ ] `cargo test` passes.

### Tests

* Existing call-related tests must still pass.

### Junie instructions

**You MAY:**

* Remove unused fields from the frame.
* Refactor call/return code to match the new structure.

**You MUST NOT:**

* Introduce closure or coroutine logic yet.
* Redesign the call stack architecture.

**If unclear:**

* Ask before changing frame responsibilities.

---

# PR-2.6 — Remove Dead Runtime Modules and Symbols

### Briefing

After the VM reset, there will be leftover modules, helpers, or symbols that are no longer referenced. This PR performs a final cleanup pass.

### Target

* Remove dead or unreachable runtime code.
* Ensure the VM crate has a minimal, clean surface.

### Work items

* Use compiler warnings and search tools to find:

  * Unused modules.
  * Unused structs/enums/functions.
  * Legacy HIP/RC terminology.
* Remove dead code.
* Update module trees and public exports.

### Acceptance checklist

* [ ] No dead modules remain.
* [ ] No HIP/RC terminology found in the VM crate.
* [ ] `cargo test` passes.

### Tests

* Existing tests only.

### Junie instructions

**You MAY:**

* Remove unused code and modules.
* Update `mod.rs` and exports.

**You MUST NOT:**

* Remove code that is still referenced.
* Replace deleted modules with new experimental ones.

**If unclear:**

* Ask before deleting anything that looks structurally important.