ext-eventius

Public extension-definition repo for the Eventius occasion family — ToGethered, RSVP.express verticals, and the Eventius/Invitus event stack — per the ext-<id> convention and the extension backend architecture standard.

backend/

Go module github.com/sneat-co/ext-eventius/backend.

Dependency policy: stdlib only. No dalgo, no sneat-go-core, no other extension. This keeps the module publicly buildable in any CI without GOPRIVATE/PAT and avoids the version treadmill the architecture standard exists to escape.

Package participation

The single vocabulary for participation-response scales across the occasion family. It satisfies the "types needed by several extensions → ext-<id>/backend contract module" row of the extension-backend-architecture decision ladder.

Before this module the occasion family had four diverging response scales maintained in isolation:

Previous location	Scale
togethered/backend IntentDbo.Likelihood	no · unlikely · maybe · likely · yes
eventius/backend RsvpStatus	yes · no · maybe
gameboard/backend RsvpStatus (game_invite.go:82-88)	going · maybe · out
rsvp-express/practice-training spec	available · unavailable · maybe

This package is the single source of truth; those implementations should import here.

Types

Type	Description
Level	Five-point graded scale: no < unlikely < maybe < likely < yes. Stored as-is in Firestore by togethered/backend.
Coarse	Three-point quick-answer scale: yes | no | maybe. Matches eventius/backend RsvpStatus and personal-events RSVP.
Availability	Alias rendering of Coarse for practice-training (available=yes, unavailable=no, maybe=maybe). Not a third scale.
GameResponse	Alias rendering of Coarse for gameboard/backend (going=yes, out=no, maybe=maybe). Not a third scale.

Canonical mappings

• Level.Coarse() — lossy: yes,likely→yes; maybe→maybe; unlikely,no→no.
• Coarse.Level() — lossless embedding: yes→yes; maybe→maybe; no→no.
• Availability.Coarse() / AvailabilityFromCoarse() — alias round-trip.
• GameResponse.Coarse() / GameResponseFromCoarse() — alias round-trip.

Parsing

ParseLevel(string) and ParseCoarse(string) are strict wire-value parsers. They do not interpret natural-language phrases ("probably" → likely); phrase mapping is a conversational-layer concern that stays in sneat-bots.

NON-GOALS

This package deliberately omits:

• Notification policy (who gets notified at which level) — extension policy owned by togethered/backend; this module must never grow predicates such as NotifiesFollowers().
• Co-presence eligibility — likewise extension policy; the "co-presence at ≥ likely" rule belongs in togethered, not in vocabulary.
• NL phrase parsing — see Parsing above.

Current and prospective consumers

Consumer	How it uses this module
togethered/backend	Stores IntentDbo.Likelihood as Level; uses Level.Coarse() for the coarse quick-answers and Level.AtLeast(LevelLikely) for co-presence edge evaluation.
rsvp-express personal-events	Stores RSVP status as Coarse.
rsvp-express practice-training	Stores session availability as Availability; converts to Coarse for shared roster logic.
eventius/backend	Replaces local RsvpStatus with Coarse; existing stored values ("yes", "no", "maybe") are identical.
gameboard/backend	Replaces local RsvpStatus (going/maybe/out) with GameResponse; backward-compatible read/write of existing records.
invitus mapping	Maps accepted→CoarseYes, declined→CoarseNo; the mapping code stays in sneat-core-modules, which imports this vocabulary.

Scale changes

Adding, removing, or reordering values in Level or Coarse requires an explicit owner decision (alexander.trakhimenok@gmail.com): every stored value and every consumer is affected. Availability and GameResponse are derived alias renderings and can gain new helpers without a scale-change review.

frontend/

Nx workspace whose ext-eventius-contract project publishes @sneat/extension-eventius-contract. Eventius implementation stays private in sneat-co/eventius.