Why: the frozen exec port could not express per-request model, tool
allowlist, skills, budget, or identifiers, so squad roles and product
profiles had no way to steer one execution; contract v0.1.0 semantics
(budget/cancel) stayed unconsumed (parity-matrix #4/#10/#16).
Evidence: go vet ./... clean; go test ./... all ok, including new
loop budget caps (tool calls, prompt tokens, deadline), cancel
propagation into a blocking tool, registry Restrict fail-closed
policy tests, native adapter v2 tests (model override, allowlist,
deadline-bound context, execution-id log header, skills prompt line),
and settle classification marking budget_exceeded permanent.
Impact: exec.Request gains optional Model/ToolAllowlist/Skills/Budget/
SessionScope/ExecutionID/Env (zero value = legacy behavior); runtime
loop enforces a shared budget and emits budget_exceeded events;
adapters/native consumes all new fields. Consumers on the old port
keep compiling and behaving identically.
Refs: docs/parity-matrix.md rows #4/#10/#16 (Batch2 scope); deps/
development-guidelines standards/agent-execution.md (shared budget
across retry layers).