The Pipeline Framework

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Query means: observe something new ​

Explicit propagation should not become ideology.

Sometimes a downstream computation does not want the value observed earlier.

It wants a new observation.

Examples include:

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current exchange rate
current inventory
latest entitlement
current market price
present external status

Carrying yesterday's value forward would be incorrect if the semantics require today's value.

That is exactly what Query expresses.

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known execution-local fact
        → carry

fresh external observation
        → Query

This is a much stronger distinction than:

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if data is in the database
    → query database

The location of the data does not determine the architecture.

Its semantics do.

If the computation already knows the relevant fact, propagating it may be correct even if an equivalent row exists in a database.

If the computation needs a fresh observation, Query is correct even if an older value is already flowing through the pipeline.

Effects have their own authority ​

Changing the outside world is different again.

An archive operation, payment, email or notification is not merely another value lookup.

It is an effect.

That is Command territory.

And TPF deliberately keeps the durable authorities separate:

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Pipeline cache
    = versioned pipeline-result replay

Query capture
    = replay of external observations

CommandEffectStore
    = identity and outcome of external effects

Persisted typed values
    = application and execution history

These mechanisms solve different problems.

They should not be collapsed into a mutable application registry that attempts to remember:

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what the pipeline knew
what it observed
what it executed
what failed
what should retry
what the user confirmed

That creates a second workflow engine beside the first.

TPF already has better places for those facts.