Budget scopes (budget.scope_v1)

Budget scopes are a compiler/runtime primitive for local resource contracts. They let you put deterministic caps around a specific region of code so agent edits can’t accidentally blow up cost elsewhere.

AST shape

["budget.scope_v1",
  ["budget.cfg_v1",
    ["mode", "trap_v1"],
    ["label", ["bytes.lit", "parse_headers"]],

    // optional caps (0 = unlimited):
    ["alloc_bytes", 65536],
    ["alloc_calls", 0],
    ["realloc_calls", 0],
    ["memcpy_bytes", 1048576],
    ["sched_ticks", 0],
    ["fuel", 0]
  ],
  <body_expr>
]

Notes:

• budget.cfg_v1 is a descriptor; use it only as the first argument to budget.scope_v1.
• mode and label are required. All caps are optional.

Modes (budget.cfg_v1.mode)

• trap_v1: on budget violation, trap at scope exit (deterministic trap code).
• result_err_v1: on budget violation, overwrite the scope result with a budget error code.
  • Only valid when the scope body evaluates to a result_* type.
  • Budget violations take precedence over any existing error code.
• stats_only_v1: track stats but never trap / return budget errors.
• yield_v1: uses sched_ticks as a deterministic yield trigger (instead of trapping). Other caps still trap.

Arch-driven scopes (budget.scope_from_arch_v1)

To keep budgets pinned and reviewable, store them as data under arch/budgets/ and reference them by id:

["budget.scope_from_arch_v1",
  ["bytes.lit", "hot_parse_v1"],
  <body_expr>
]

This loads:

• arch/budgets/profiles/hot_parse_v1.budget.json (schema_version: "x07.budget.profile@0.1.0")

x07 arch check can:

• validate the budgets index: arch/budgets/index.x07budgets.json (schema_version: "x07.arch.budgets.index@0.1.0")
• enforce that selected boundaries are wrapped in budget.scope_from_arch_v1
• enforce that profile_id is declared in the budgets index