fix: make GenomeEvent use template literal type for proper union narrowing

[lucamorettibuilds]

Fixes #78.

Problem

GenomeEvent = { t: string; type: string; [key: string]: unknown } is a catch-all that absorbs all other members of the Event discriminated union. TypeScript can't narrow event.type === 'creature.boot' because GenomeEvent also matches — forcing as any casts on every property access after narrowing.

Solution

Option A from #78: Make GenomeEvent.type a template literal genome.${string}.

This creates a clean namespace boundary:

• host.* and creature.* events have literal type strings → TypeScript narrows them perfectly
• genome.* events are genome-specific and don't overlap

Additional changes

• Added missing event types that were using as any to emit:
  • HostEvent: budget.exceeded, budget.reset, narrator.entry
  • CreatureLifecycleEvent: creature.spawning, creature.spawned, creature.spawn_failed
• Added janeeVersion to creature.boot type (was accessed via as any cast)
• Removed all 5 as any casts from index.ts — they're no longer needed since narrowing works correctly

Migration note

Any genome that emits events with types not prefixed genome. will need to update their event type strings. The host and creature lifecycle events are all accounted for in the updated types.

[openseed-patch]

Reviewed the diff carefully and compiled on the branch — clean build.

This is the right fix. The genome.${string} template literal creates a clean namespace boundary that lets TypeScript's discriminated union narrowing actually work. The result: all 5 as any casts gone, and lines 373 and 437 (the ones I flagged in #78 as the remaining hard cases) are fixed too, not just the emit sites.

A few things I checked:

narrator.entry shape — the type definition { text: string; blocks?: Record<string, string>; creatures_mentioned: string[] } matches exactly what narrator.ts emits at line 386–390. No mismatch.

creature.request_restart narrowing — previously (event as any).reason on line 373. Now event.reason works because with GenomeEvent excluded from the creature.* namespace, the guard event.type === 'creature.request_restart' correctly narrows to the CreatureLifecycleEvent variant that has reason: string.

creature.boot narrowing — same fix applies to line 437, event.janeeVersion now resolves cleanly.

Migration note — the PR description correctly calls this out: any genome emitting events without a genome. prefix will break at the type level. That's the right tradeoff. If a genome event type doesn't start with genome., it's using a reserved namespace it shouldn't be touching anyway.

Overlap with PR #77 — #79 is a strict superset of #77. Recommend closing #77 in favour of this one to avoid a rebase conflict.

One minor observation: narrator.entry is added to HostEvent rather than its own category. That's fine — it's emitted by the host process. But if the narrator grows more event types later, it might be worth a NarratorEvent subtype. Not worth doing now.

Ship it.