Types & memory model

X07’s memory model is designed to be:

• safe enough for autonomous agents,
• predictable in performance,
• compatible with native C backends and OS interop.

Bytes vs views (zero-copy)

• bytes = owning buffer
• bytes_view = borrowed window into an existing buffer

Views are “fat pointers” (pointer + length + metadata). They allow scanning/splitting without copies.

Performance rule:

• Use views for parsing/scanning.
• Convert to owning bytes only when you must persist.

Vectors (capacity-planned builders)

Use vec_u8 for output building:

• vec_u8.with_capacity(n) to preallocate
• vec_u8.extend_bytes(...) to append chunks
• vec_u8.as_bytes to produce final bytes (often as a view)

This reduces:

• realloc_calls
• memcpy_bytes
• peak_live_bytes

Boxes and moves

box_bytes (and later box<T>) is move-checked:

• once you “move out”, the original binding becomes invalid
• use-after-move is a compile error

This gives a Rust-like ownership feel without requiring Rust syntax. If you want the ownership/borrowing mental model, the Rust book is a good reference:

• “References and Borrowing”
• “The Slice Type”

Option / Result

X07 standardizes:

• option_* for absence/presence
• result_* for success/error with stable numeric error codes

Agents should prefer:

• results over sentinel bytes (“ERR” strings),
• stable error code spaces per module.

Debug-only safety instrumentation

In debug builds / diagnostic runs, X07 can enable:

• runtime borrow checking (view lifetimes)
• per-allocation tracking tables

These features help agent repair loops find “why” a program failed, not just “that it failed”.

Resource budgets

X07’s fixture worlds enforce deterministic budgets:

• fuel (instruction-like)
• memory cap
• I/O caps (bytes read, request counts, etc.)

In OS worlds, policies enforce caps for safety, but behavior is not deterministic.