Add typed event payloads for frontend type safety

[iamnbutler]

Summary

• Defines typed interfaces for all known event data payloads (OrchestratorDecisionData, AgentErrorData, HumanMessageData, etc.) in web/src/lib/types.ts
• Adds isEventType() type guard that narrows Event.data to the correct payload shape based on event.type
• Replaces Record<string, unknown> casts and manual typeof field checks in task-detail.tsx, orchestrator/page.tsx, and automation-detail.tsx with typed access
• Adds typed AgentParsedMessage and AgentContentBlock types for the JSON messages parsed from agent stdout

Test plan

• TypeScript compiles with no errors (tsc --noEmit)
• Vite production build succeeds (bun run build)
• Verify event rendering in task detail, orchestrator, and automation detail pages works correctly at runtime

Closes #521

🤖 Generated with Claude Code

[github-actions]

Good structural improvement overall — the EventDataMap + isEventType guard pattern is clean, and the consumer-side callsites are noticeably cleaner as a result. Two issues worth addressing before merge.

Overview of findings:

• The agent:message event type is registered in EventDataMap and AgentMessageData has the right text?: string field — but neither task-detail.tsx nor automation-detail.tsx actually guards through isEventType(event, "agent:message") before accessing event.data.text. Both files still cast back to Record(string, unknown) on that path. This is the hottest path in both pages and the main reason the PR exists, so it's worth fixing.

• TypedEvent(T) is exported but Event = UntypedEvent means nothing is ever inferred as TypedEvent(T) — it's structurally dead. Either remove it or widen Event to a proper TypedEvent | UntypedEvent union so it pulls its weight.

Two suggestions (non-blocking): d.approved === true in the orchestrator page can drop the === true since approved is now typed boolean, and AgentMessageData.stream appears to be unused.

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References:

• §23813144207

Reviewed by PR / Review

[github-actions]

[IMPORTANT] Priority: Code Quality / Type Safety

agent:message is the most common event on this page, yet it still falls through to a Record(string, unknown) cast rather than using the new isEventType guard. This is the exact pattern the PR is meant to eliminate, but it was skipped here.

AgentMessageData already has text?: string. The fix is to guard before accessing:

if (!isEventType(event, "agent:message")) continue;
const raw = event.data.text;

Without this, the as Record(string, unknown) cast is still needed and the typed system provides no benefit for the core parsing path.

[github-actions]

[IMPORTANT] Priority: Code Quality / Type Safety

Same issue as in task-detail.tsx: the agent:message path wasn't narrowed and still falls back to (event.data as Record(string, unknown))?.text. Both files share the same parseAgentEvents logic and have the same gap — adding isEventType(event, "agent:message") before this fallthrough would close it in both places.

[github-actions]

[SUGGESTION] Priority: Code Quality

TypedEvent(T) is defined but Event = UntypedEvent means it's never the inferred type of any value — no function signature accepts or returns it, and isEventType narrows to Event & { type: T; data: EventDataMap[T] } rather than TypedEvent(T). It's currently dead-exported.

Two clean options:

1. Remove TypedEvent(T) — the isEventType guard + intersection approach is self-contained.
2. Make Event a proper union: export type Event = TypedEvent | UntypedEvent — this would let consumers see the full discriminated union and TypeScript could help exhaustiveness-check event.type branches.

[github-actions]

[SUGGESTION] Priority: Code Quality

d.approved === true is redundant — OrchestratorDecisionData.approved is typed boolean (not boolean | undefined), so this simplifies to d.approved. The === true form was meaningful in the old event.data?.approved === true guard against unknown, but now that the type is asserted it adds noise.

[iamnbutler]

Orchestrator Evaluation: Rejected

The PR makes a solid structural improvement by introducing typed event payloads, an EventDataMap, and an isEventType() type guard. The consumer callsites are noticeably cleaner. However, there are two issues that prevent approval:

1. CI is failing — The metadata explicitly states 'CI Status: ✗ FAILING — DO NOT APPROVE'. This alone is a blocker.

2. The Event type alias defeats the purpose of the type system. Line export type Event = UntypedEvent; means that Event is always just UntypedEvent with data: Record<string, unknown>. The TypedEvent type is defined but never actually used — it's exported but no consumer code references it. The isEventType guard narrows Event (which is UntypedEvent) to Event & { type: T; data: EventDataMap[T] }, which works at the callsites, but there's no compile-time protection when constructing or receiving events. If the backend changes event structure, the frontend still silently accepts anything as Record<string, unknown> in the data field. The type narrowing only helps at consumption sites, not at boundaries. This is a partial solution — it's better than before, but the PR description and issue claim compile-time protection which isn't fully achieved.

3. Residual Record<string, unknown> casts remain. In both task-detail.tsx and automation-detail.tsx, there's still const raw = (event.data as Record<string, unknown>)?.text; — this is exactly the pattern the issue wants to eliminate. For agent:message events, the code doesn't use isEventType(event, 'agent:message') to narrow the type before accessing .text, instead falling back to the unsafe cast. The github-actions review also flagged this: the agent:message type is in the EventDataMap but the main parsing path for agent messages doesn't use the type guard.

4. Minor: approved: d.approved === true — In the OrchestratorDecisionData interface, approved is typed as boolean (not optional), so === true is redundant but harmless.

The approach is good and the EventDataMap pattern is clean, but CI failure is a hard blocker, and the incomplete narrowing for agent:message events leaves a gap.

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Feedback for agent:
Cannot approve due to failing CI. Additionally:

1. In task-detail.tsx:189 and automation-detail.tsx:220, the code still uses (event.data as Record<string, unknown>)?.text instead of narrowing with isEventType(event, 'agent:message') first. This defeats the purpose of the typed event system for the most common event type. The agent:message entry exists in EventDataMap but isn't used at the primary parsing path.

2. export type Event = UntypedEvent; means TypedEvent is defined but effectively unused — events are always untyped at the type level. Consider making Event a proper discriminated union (e.g., type Event = TypedEvent<'orchestrator:decision'> | TypedEvent<'orchestrator:feedback'> | ... | UntypedEvent) so that TypeScript can provide exhaustiveness checking.

3. Fix CI before requesting re-review.