## What was broken

Slack agents stopped responding. A user `@mention` becomes an
`agent/input-added` event on the routed agent stream, but **nothing
consumes it** — the LLM processors (`agent-chat` / `agent` / the
provider processor) were never registered on Slack-routed streams.
Observed live on `templestein2` stream
`/agents/slack/c09trdv61v4/ts-1780670924-517029`: `slack-agent` ran
(produced the input), but no `agent`/LLM processor existed, so no reply.

## Root cause — regression from #1370 (streams runtime cutover)

- **Old runtime:** `routedStreamBootstrapEvents` subscribed a *callable*
to `AGENT` DO `afterAppend`. Invoking it woke `AgentDurableObject` →
`onInstanceWake` registered `agent-chat`/`agent`/LLM/`agent-host` +
seeded setup events.
- **After #1370:** that was replaced with a built-in `agent-host`
processor whose `afterAppend` only runs `ensureChildAgentRunner` (+
codemode handlers). It never wakes the agent for its own stream, so the
LLM processors are never registered.
- What actually *starts* a processor is the `subscription-configured`
event (`Stream#reconcileOutboundConnections` dials a runner per
subscription key). Those were never appended for the LLM processors on
routed streams.
- Compounding: `ensureChildAgentRunner` compared against the legacy
`events.iterate.com/core/child-stream-created`, but the new runtime
emits `events.iterate.com/stream/child-stream-created`.

Dashboard-created agents were unaffected because `new.tsx` explicitly
subscribes the full processor set. **PR #1371 would not have fixed
this** — it only adds `stream-processor-registered` *marker* events
(which don't start processors) and only to the UI flow.

## The fix

- **Wake the agent for routed streams**
(`ensureAgentRunnerForOwnStream`): when `agent-host` runs on a routed
agent stream, on the `stream/created` event it initializes that stream's
`AgentDurableObject` → `onInstanceWake` registers the LLM processors and
setup events; the resulting `subscription-configured` events are what
`reconcileOutboundConnections` dials. Verified the runner replays from
offset 0 (`replayAfterOffset: snapshot?.offset ?? 0`), so `agent-host`
reliably sees `stream/created` (always offset 1).
- **Dedupe the agent-host runner:** align the bootstrap `agent-host`
subscription key with the canonical `AgentDurableObject` key (runner DOs
are keyed by `${namespace}:${path}:${subscriptionKey}`), so the two
declarations resolve to one runner.
- **Use the new-runtime `events.iterate.com/stream/` prefix** at the OS
call-sites that compare against new-runtime core events: the broken
`child-stream-created` check (local constants), the project agents-root
jsonata matcher, and the stream-composer UI examples.

## Verification

- Full-repo `pnpm typecheck` (18 projects), `oxlint`, `oxfmt`
- Affected OS unit tests pass
- Not yet deployed / round-tripped on a preview — recommend a preview
deploy + one test `@mention` before prod (`Preview / e2e` is otherwise
skipped on PRs).

## Scope note

An earlier revision also did a broad `events.iterate.com/core/` →
`/stream/` rename across the shared package and the separate
**events.iterate.com** app. That **broke the events runtime e2e**
(append → 500) and is unrelated to this bug, so it was reverted out of
this PR. If we still want the events platform on the `/stream/` prefix
it needs its own investigation — tracked as a follow-up.

## Follow-ups (found while auditing #1370)

- `ProjectDurableObject.afterAppend` is **orphaned**: the old runtime
forwarded lifecycle events to the project config-worker `afterAppend`
hook; the new built-in `project-lifecycle` processor has no
`afterAppend` and nothing calls it.
- `CodemodeSession.afterAppend` is orphaned (likely benign — resolves
locally via `appendAndConsume`).
- `agents.e2e.test.ts` has vacuous `/core/error-occurred` assertions;
worth real Slack-path e2e coverage so this can't regress silently.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

<!-- CLOUDFLARE_PREVIEW -->
## Environment Config Lease
<!-- CLOUDFLARE_PREVIEW_STATE -->
<!--
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<!-- /CLOUDFLARE_PREVIEW_STATE -->
Lease: `preview-2`
Doppler config: `preview_2`
Type: `environment-config-lease`
Leased until: 2026-06-05T20:19:56.123Z

### OS
Status: deployed
Commit: `2ba51d8`
Preview: https://os.iterate-preview-2.com
[Workflow
run](https://github.com/iterate/iterate/actions/runs/27035212234)
Updated: 2026-06-05T19:21:55.576Z
<!-- /CLOUDFLARE_PREVIEW -->

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Touches agent stream bootstrap and durable-object initialization on
every routed agent stream; wrong event matching or wake ordering could
affect non-Slack agents, but changes are narrowly scoped to host
processor and Slack routing.
> 
> **Overview**
> Restores **Slack-routed agent streams** after the streams runtime
cutover (#1370): routed streams only got `slack-agent` + `agent-host`,
so `agent/input-added` events were never consumed because LLM processors
were never registered.
> 
> **`ensureAgentRunnerForOwnStream`** initializes the stream’s
`AgentDurableObject` on `events.iterate.com/stream/created` (via
`agent-host` `afterAppend`, using **`keepAlive`** to avoid deadlocking
catch-up). That runs `onInstanceWake`, which appends the LLM processor
subscriptions and setup events.
> 
> **Slack bootstrap** now uses
**`agentProcessorSubscriptionConfiguredEvent`** so the routed
`agent-host` subscription key matches `AgentDurableObject`, deduping to
a single runner.
> 
> **Event type alignment** for the new runtime: `child-stream-created`
and related core lifecycle types use `events.iterate.com/stream/…`
instead of legacy `…/core/…` in agent host logic, the agents-root
jsonata matcher, and stream composer presets.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
2ba51d8. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>