Spec proposal: OVOS-TRANSFORM-1 — Transformer Plugins (six lifecycle hooks)

[JarbasAl]

Tracking issue for PR #20 — OVOS-TRANSFORM-1: Transformer Plugins

The OVOS transformer ecosystem runs six plugin types as ordered chains at fixed points around the utterance lifecycle: audio (pre-STT), utterance (post-STT), metadata (post-utterance), intent (post-match, pre-dispatch), dialog (post-skill, pre-TTS), and TTS (post-TTS, pre-playback). All six share the same shape but have no normative contract.

Proposal

OVOS-TRANSFORM-1 unifies the six types under one spec:

• One abstraction — a transformer is a black-box component identified by an opaque transformer_id that always runs at its hook (unlike a pipeline plugin, which decides whether to claim).
• Six lifecycle hooks at the fixed points above.
• Per-type IO contracts — permitted mutations, canonical use cases, and a Where LLMs fit note per stage.
• Intent transformer = canonical home for system-entity injection (dates, numbers, durations, ordinals) into match captures. The agreed pathway for applying typed normalisation globally.
• Ascending priority (lower number = earlier; default 50). Deployer-configured explicit order wins over priority.
• Per-session chain overrides via six optional session.*_transformers list fields.
• Passive registration index per type — ovos.transformer.<type>.list / .response.
• Robust error handling — exceptions and shape violations become no-op transforms; the orchestrator logs and proceeds.

Out of scope

• Typed-value schemas for injected entities (future text-normalisation spec).
• Per-plugin behavioural contracts.
• Cross-transformer coordination protocols.
• Hot reload, timeout policy, plugin loading and discovery.