Agents Test Performance

Agent tests are often import-bound. Treat slow test files as architecture signals, not just runner noise.

Guardrails

Benchmark before and after performance edits. Prefer existing grouped artifacts when comparing suites, or use /usr/bin/time -l pnpm test <file> for a scoped hotspot.
If a test only needs schema, capability, routing, or static discovery data, do not cold-load full bundled plugin/channel/provider runtime. Add or reuse a lightweight typed artifact and keep full runtime as a fallback.
Keep expensive bootstrap, embedded runner, provider, plugin, and channel runtime work behind dependency injection or narrow helpers so tests can cover behavior without starting the whole runtime.
Treat channel/plugin lookups inside agent hot paths as suspect. If the code only needs target parsing, peer-kind inference, setup hints, or static descriptors, use a local pure helper or lightweight public artifact before reaching for getChannelPlugin() / bundled runtime fallback.
In spawn/session/requester-origin logic, keep routing and delivery-context normalization deterministic and runtime-free. Add explicit parser coverage for channel-specific prefixes instead of loading a channel plugin just to classify a target.
If moving coverage out of a slow integration test, preserve the exact production composition in a named helper and test that helper. Do not remove the behavior proof just because the old proof was slow.
Avoid broad importOriginal() partial mocks and module resets in hot agent tests. Use explicit mock factories, one-time imports, and reset only the state the test mutates.

For agent performance changes, record seconds and RSS before/after in the handoff or benchmark report.
If the change touches lazy-loading, plugin runtime imports, or bundled artifacts, run pnpm build.