Converse and Fallback Services

Both services are pipeline plugins shipped inside ovos-core and registered via its own entry points.

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ConverseService

Module: ovos_core.intent_services.converse_service.ConverseService Pipeline plugin ID: ovos-converse-pipeline-plugin Stage name: converse

Converse allows active skills to intercept utterances before general intent matching. A skill is "active" if it recently handled an utterance. Active skills are stored in the Session object.

How It Works

1. converse stage is hit in the pipeline
2. ConverseService.match() iterates active skills in priority order
3. For each skill, emits {skill_id}.converse.request and waits for a response
4. If the skill returns True, the utterance is consumed
5. If not, the next active skill is tried

Converse Modes

Controlled by ConverseMode and ConverseActivationMode from ovos-workshop:

• ConverseMode — restricts which skills may participate in converse
• ConverseActivationMode — controls when a skill becomes active (e.g. only when it handled the last utterance)

get_response Support

During skill.get_response, the skill temporarily holds the converse channel:

• skill.converse.get_response.enable → lock converse to this skill
• skill.converse.get_response.disable → release lock

Bus Events Handled

Event	Handler
intent.service.skills.activate	handle_activate_skill_request
intent.service.skills.deactivate	handle_deactivate_skill_request
intent.service.active_skills.get	handle_get_active_skills
skill.converse.get_response.enable	handle_get_response_enable
skill.converse.get_response.disable	handle_get_response_disable
converse:skill	handle_converse

Broadcast Contest Poll (OVOS-CONVERSE-1 §4.2)

Alongside the sequential per-skill {skill_id}.converse.request above, ConverseService also emits one broadcast ovos.converse.ping per round on the static spec topic. It carries no candidate identity — the session already names the active skills — and every active skill answers on the shared pong topic. The legacy per-skill pings still go out alongside it: no released ovos-workshop vintage binds the broadcast topic yet, so dropping the legacy leg would silence every skill in the field. Each poll round is correlated by utterance_id and session, so a late pong from a stale round is discarded instead of winning the wrong round.

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FallbackService

Module: ovos_core.intent_services.fallback_service.FallbackService Pipeline plugin ID: ovos-fallback-pipeline-plugin Stage names: fallback_high, fallback_medium, fallback_low

Fallback skills handle utterances that nothing else could match. They register with a priority number (lower = higher priority).

How It Works

1. A fallback stage is hit in the pipeline
2. FallbackService.match_high/medium/low() filters registered fallbacks by priority range
3. For each fallback skill (sorted by priority), emits a converse-style request
4. First skill that returns True wins

Priority Ranges

Stage	Priority range
fallback_high	0–49
fallback_medium	50–89
fallback_low	90–100+

Priority overrides can be set in config:

{
  "skills": {
    "fallbacks": {
      "fallback_priorities": {
        "my-skill-id": 10
      }
    }
  }
}

FallbackMode

Controlled by FallbackMode from ovos-workshop:

• Restricts which skills are allowed to act as fallbacks (e.g. skill owner, anyone, or disabled)

Bus Events Handled

Event	Handler
ovos.skills.fallback.register	handle_register_fallback
ovos.skills.fallback.deregister	handle_deregister_fallback

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StopService

Module: ovos_core.intent_services.stop_service.StopService Pipeline plugin ID: ovos-stop-pipeline-plugin Stage names: stop_high, stop_medium, stop_low

Handles "stop" / "cancel" utterances. Active skills are asked to handle the stop request in priority order. Configured under skills.stop in mycroft.conf.

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Cross-References

Skill base classes for converse and fallback

Skills that participate in converse or fallback inherit from special base classes in ovos-workshop:

Class	Module	Docs
ConversationalSkill	ovos_workshop.skills	ovos-workshop/docs/skill-classes.md
FallbackSkill	ovos_workshop.skills	ovos-workshop/docs/skill-classes.md
OVOSSkill (base, has self.converse())	ovos_workshop.skills.ovos	ovos-workshop/docs/ovos-skill.md

Mode enums (ovos-workshop)

ConverseMode, ConverseActivationMode, and FallbackMode control who can participate and when. Defined in ovos_workshop.skills.common_query_skill and ovos_workshop.skills respectively → ovos-workshop/docs/permissions.md.

Session & active skills

Active skills are tracked in Session.active_skills — ovos_bus_client.session.Session. The converse service reads and updates this list via sess.activate_skill() / sess.deactivate_skill(). See ovos-bus-client/docs/session.md.

Intent decorators for converse

Skills declare converse handlers with @converse_handler from ovos-workshop → ovos-workshop/docs/decorators.md.

Full bus events list

See bus-events.md for the Converse and Fallback event reference.

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