# Comparison Execution Internals

The comparison execution core receives an already prepared report and an
already inspected, ordered profile list. It initializes an outcome for every
selected profile, launches each started profile in its own goroutine, and
waits for every started goroutine before returning. Results retain the supplied
selection order even though execution completes in an arbitrary order.

Every profile uses the exact inspected prompt identity and a private copy of
the same prepared data package. Provider, generated-text validation, rendering,
or debug-write failure becomes that profile's safe failed outcome and does not
cancel its peers. The application deliberately imposes no additional semaphore:
Promptkit owns backend capacity. Cancellation or a deadline marks unfinished
outcomes as skipped or failed, joins work, and prevents bundle publication.

When debugging is enabled, each execution receives a deterministic reference
derived from the comparison identity, ordered profile position, and safe
profile slug. This keeps concurrent captures separate. The debug writer itself
owns secure-root validation and file permissions. It safely creates shared
missing ancestors during concurrent writes, then rejects symlink and non-
directory components. Operational retention and sensitivity are documented in
the [operations guide](../operations.md).

The output result and its safe errors are converted into the durable contract
only by comparison publication. See [comparison publication
internals](comparison-publication.md) and the external [comparison bundle
contract](../integrations/comparison-bundle.md).