Phase 7: the reactor now branches on agent backend kind.
Reactor changes (internal/reactor/reactor.go):
* Adds `registry *harness.Registry` field + `SetHarnessRegistry`.
* `agentBackendKind()` picks k8s | subprocess | webhook | none from
the agent's `HarnessName`, `K8sImage`, `LocalCommand`, and
`HarnessConfigJSON` fields. Explicit `HarnessName` wins.
* `evaluateTrigger` applies the same preconditions (depth, daily
budget, cooldown, already-running, pending_work coalescing) to
every backend — a subprocess agent mentioned in a channel now
goes through the exact same rate limits a K8s agent does.
* K8s agents keep the existing `createJob` fast-return path with
the async poller for restart safety. Non-K8s agents use a new
`dispatchHarness` that inserts the reactive_runs row, spawns a
detached goroutine, blocks on `Registry.Execute`, and writes the
terminal status / error_log / metrics / failure DM on return.
* Import `harness`, `messaging`, `google/uuid` for building the
ExecRequest.
main.go wiring:
* Build one `harness.Registry` with all three real backends:
`k8sjob.New(k8sRunner, …)`, `subprocess.New(Config{BaseDir:
dataDir/harness/subprocess}, …)`, `webhook.New(Config{}, …)`.
* Attach a `runs.Store` as the registry Observer so every dispatch
writes a harness_runs row — no per-caller code required.
* Hand the registry to the reactor via `SetHarnessRegistry`.
* Log the registered backend names at startup.
Tests (internal/reactor/reactor_test.go):
* New `insertSubprocessAgent`, `newHarnessReactor`, `waitForRun`,
and `fakeNotifier` helpers.
* Seven new tests that register a stub harness under "subprocess"
and verify: success from @mention, failure recorded + DM sent,
depth-exceeded skipped, budget-exhausted skipped, cooldown
skipped, already-running queued, no-backend fails cleanly. Each
checks the harness stub is NOT called when a precondition skips.
* Existing `TestReactorNoK8sImage` keeps working — the old
k8s-specific error message is replaced with the backend-agnostic
"no backend configured" phrasing.
* `setupTestDB` now pins `SetMaxOpenConns(1)`: modernc.org/sqlite
in-memory DBs give each pool connection a fresh empty database,
which races the new dispatchHarness goroutine and main-test
goroutine. Pinning is the standard workaround.
The overall behaviour: `@local-agent` in a channel message now starts
the configured subprocess/webhook under the same depth/budget/cooldown
rate limits as a K8s agent, tracked in reactive_runs and harness_runs,
instrumented with an OTel span, with trace context propagated into the
child via env vars. Failure DMs go to the human owner, as with K8s.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
