feat(kitchen-sink): add actor probe controls

[NathanFlurry]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[NathanFlurry]

• fix(pegboard): align drain grace defaults with stop threshold #4958 : 2 dependent PRs (#4960 , #4966 )
• fix(rivetkit): preserve bridge error messages #4959
• fix(rivetkit): fire abort signal on shutdown finalize #4957
• fix(rivetkit): use startup kv preload #4956
• fix(client): flatten skipReadyWait option #4955
• ci(publish): add manual preview publish flow #4954
• fix(depot): add ltx decode diagnostics #4953
• fix(universaldb): preserve plain set values #4952
• fix(universaldb): align versionstamp operand encoding #4951
• fix(rivetkit): export database provider types #4950
• wip: kitchen sink agentic loop finish #4949
• chore(rivetkit): note duplicate admission logic #4948
• test(rivetkit): cover bypass fetch header forwarding #4947
• feat(kitchen-sink): add actor probe controls #4946 👈 (View in Graphite)
• fix(gateway): split actor response wait errors #4945
• fix(guard): handle bypass preflight before query parse #4944
• feat(kitchen-sink): add mock agent event log copy #4943
• fix(kitchen-sink): default mock agent to local endpoint #4942
• test(rivetkit): enable driver lifecycle regressions #4941
• test(rivetkit): verify cached websocket db refs exceed grace #4940
• fix(rivetkit-core): keep sleeping actors reachable during grace #4939
• test(rivetkit): cover async websocket close db access #4938
• fix(rivetkit): keep actors awake until keepAwake work finishes #4937
• fix(rivetkit): persist native onSleep state on errors #4936
• fix(rivetkit-core): allow dispatch during sleep grace #4935
• fix(rivetkit): make duplicate sleep requests idempotent #4934
• main

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[claude]

Code Review: feat(kitchen-sink): add actor probe controls

Overview

This PR adds actor probe controls to the kitchen-sink example, including:

• A new HealthPanel component for gateway health checks on individual actors
• Test HTTP and Test WS buttons (non-bypass variants) in the MockAgenticLoopPanel
• A Health Check button in MockAgenticLoopPanel for gateway health probes
• Server-mode auto-detection in server.ts to switch between serverless and direct-start modes

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Issues

Commented-out code (server.ts)

The request logging middleware is commented out rather than removed. Either restore it, remove it, or guard it with an env flag.

Mixed state: testHttp / testWebSocket write to lastBypass

Both new functions call setLastBypass(message), so their results are mixed with the bypass test results in the same UI element. They should each have their own state variables (like lastHealth does) or share a clearly named combined state variable.

Significant code duplication

testHttp is a near-copy of testHttpBypass with the sole difference of omitting gateway: { bypassConnectable: true }. Similarly, testWebSocket duplicates testWebSocketBypass. The shared scaffolding (latency timing, error classification, stopping-actor detection, stats update) could be extracted into a small helper to reduce drift risk.

Auth inconsistency in HealthPanel

MockAgenticLoopPanel.checkHealth passes the auth token via x-rivet-token, but HealthPanel.checkHealth issues the same gateway fetch without any auth header. If the gateway requires a token, the HealthPanel ping will silently fail with a 401.

Fragile error string matching in testWebSocket

Matching on human-readable substrings like "actor.stopping" or "Server Error" is fragile. Prefer checking a structured close code or a parsed JSON code field, the same way testHttpBypass already parses the response body.

Double cast as unknown as AgenticHandle

The cast at line ~1492 signals a real type mismatch between what getOrCreate returns and the local AgenticHandle interface. The interface should be made compatible with the actual return type rather than suppressing the error through unknown.

serverlessMode naming

RIVET_RUN_ENGINE === "1" spins up the engine locally, which is semantically the opposite of serverless. The condition logic is correct, but the name is confusing. Something like useHttpHandler or externalEngineMode would be clearer.

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Minor observations

• The Unicode middle-dot loading indicator in HealthPanel works but is harder to read in source than a plain "...".
• The noteActorStopping signature simplification (building the full message outside and passing it in) is a good cleanup.
• Adding httpOk / wsOk stats alongside the bypass counters is a useful addition for distinguishing probe paths in the stats panel.