AI Package Boundary (src/ai/)

Applies to: zmodu v0.20.1+ · Gate: src/test/AiBoundary.zig

src/ai/ is an optional subsystem (~12k lines) designed so it can be extracted into a standalone package. src/test/AiBoundary.zig enforces two directional import rules on every zig build test run:

1. Core never imports src/ai/: No file under src/{core,api,data,sqlx,http,security,messaging,runtime} may @import any file in src/ai/. The single top-level re-export in src/root.zig is the only entry point.
2. src/ai/ only imports domain seams: Files inside src/ai/ may only import approved domain barrels and seams:
   • data.zig (never sqlx/sqlx.zig or persistence/backends/** directly; both baselines are frozen at 0)
   • http.zig and http/Sse.zig
   • runtime.zig (used by src/ai/agent_worker.zig to run an Agent as a runtime worker)
   • core/, messaging/, scheduler/, resilience/, tracing/, redis/, api/, security/, test/

// Disallowed in src/ai/:
// const sqlx = @import("../sqlx/sqlx.zig");

// Required: import through the domain barrel
const data = @import("../data.zig");

Any new import outside the allowlist in src/test/AiBoundary.zig fails the test suite with error.AiBoundaryViolation.