feat(ocap-kernel): use E() for kernel service invocation to support remote presences

[rekmarks]

Description

Switches KernelServiceManager.invokeKernelService() to use E() from @endo/eventual-send instead of direct property access. This enables CapTP remote presences (whose methods aren't enumerable) to be registered as kernel service objects — a separate process can now create an exo, register it on the kernel over CapTP, and have vats invoke methods on it seamlessly.

Changes

• KernelServiceManager.ts — Replace direct service[method]() invocation with E(service)[method](), removing the manual method-exists check (E() handles this natively)
• kernel-facet.ts — Add registerKernelServiceObject to the kernel facet so it's callable over CapTP
• captp-service-client.js (new) — Worker thread that sets up a CapTP connection to the kernel, creates a test exo, and registers it as a kernel service
• captp-service-vat.ts (new) — Minimal vat that calls E(testService).doSomething(3, 4) and returns the result
• captp-service.test.ts (new) — E2E test proving the full round-trip: worker registers exo over CapTP → vat invokes method → call traverses CapTP → result returns
• service.test.ts — Fix assertion for error message format change (exact match → regex)
• captp.integration.test.ts — Add registerKernelServiceObject to mock kernel (required by makeKernelFacet)

Testing

The core behavior change is unit-tested in KernelServiceManager.test.ts (updated to cover both local exo and remote presence scenarios). The new e2e test in packages/nodejs/test/e2e/captp-service.test.ts validates the full CapTP round-trip: a real kernel, a worker thread acting as a CapTP client, and a bundled vat that invokes the remotely-registered service. The existing kernel-test service test and kernel-browser-runtime integration tests continue to pass with the updated assertions.

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Note

Medium Risk
Changes the kernel’s service invocation path to use E() (asynchronous eventual-send) and exposes service registration over the kernel facet, which can affect error propagation and method resolution for all kernel services.

Overview
Kernel services can now be implemented as remote CapTP presences. KernelServiceManager.invokeKernelService() switches from direct service[method](...) calls to E(service)[method](...), enabling proxy/presence objects whose methods aren’t enumerable.

The kernel facet now exposes registerKernelServiceObject, and tests/mocks are updated accordingly (including looser assertions around error formatting under eventual-send/SES).

Adds a Node.js e2e that spawns a worker CapTP client to register a service exo over CapTP and verifies a vat can call it end-to-end; updates dependencies (@endo/eventual-send in ocap-kernel, @endo/captp for nodejs tests).

^{Written by Cursor Bugbot for commit e9cd1c0. This will update automatically on new commits. Configure here.}

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	76.09% ⬇️ -0.02%	6632 / 8715
🔵	Statements	75.98% ⬇️ -0.02%	6738 / 8867
🔵	Functions	73.95% 🟰 ±0%	1653 / 2235
🔵	Branches	75.35% ⬇️ -0.03%	2468 / 3275

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
packages/ocap-kernel/src/KernelServiceManager.ts	93.87% ⬇️ -0.77%	88.88% ⬇️ -2.02%	100% 🟰 ±0%	93.87% ⬇️ -0.77%	193-198
packages/ocap-kernel/src/kernel-facet.ts	100% 🟰 ±0%	100% 🟰 ±0%	100% 🟰 ±0%	100% 🟰 ±0%

Generated in workflow #3884 for commit e9cd1c0 by the Vitest Coverage Report Action

[sirtimid]

LGTM!