# Runtime event mixing architecture

The runtime mixing engine is source-neutral. Source-specific behavior is contributed through four extension points:

1. `RuntimeEventSemantics` classifies an event and supplies semantic lifecycle normalization.
2. `RuntimeEventMixingRuleProvider` supplies source/domain-specific rules.
3. `RuntimeEventCompatibilityPolicy` validates candidate pairs after broad grouping.
4. `RuntimeEventFusionPolicy` enriches or transforms the retained primary event.

## Generic classifications

`RuntimeEventSourceProfile` stores opaque classifications rather than domain-specific enums. The built-in keys are:

- `sourceFamily`
- `sourceRole`
- `representation`
- `extractionCode`

The common engine does not interpret their values. A tachograph adapter currently publishes values such as `TACHOGRAPH`, `DRIVER_CARD`, `VEHICLE_UNIT`, `DATABASE`, and `FILE_SESSION`. Another source family can publish different values without changing `RuntimeEventMixingRule` or `RuntimeEventMixingService`.

## Generic rule structure

A rule consists of:

- channel and event-domain/type/lifecycle filters;
- an equivalence-key type;
- a primary `RuntimeEventSelector`;
- a secondary `RuntimeEventSelector`;
- optional `RuntimeEventPairConstraint` values, such as equal `sourceRole`;
- a compatibility-policy id;
- a fusion-policy id;
- output roles and audit text.

Source-specific values belong only in a source-specific `RuntimeEventMixingRuleProvider`.

## Tachograph plugin

The tachograph implementation is isolated in:

- `RuntimeTachographEventSemantics`
- `RuntimeTachographEventMixingRuleProvider`
- `RuntimeTachographEvidenceCompatibilityPolicy`
- `RuntimeTachographActivityCompatibilityPolicy`
- `RuntimeTachographVehicleIdentityFusionPolicy`

The generic classes do not import tachograph source-role or representation types.

## Diagnostics

Diagnostics are now emitted as generic maps:

- `sourceFamilyCounts`
- `sourceRoleCounts`
- `representationCounts`

This replaces tachograph-specific scalar counters in the event-mixing module metadata.

## Modes

- `OFF` disables all providers.
- `FULL` enables all providers that support the mode.
- The tachograph provider continues to accept the legacy `TACHOGRAPH_SAME_SOURCE` value.