Validate and preview the batch in the conversion workflow

[Andesha]

Parent

#192

What to build

Let Configuration load a saved or directly handed-off batch manifest, combine it with dataset-wide conversion settings, and pass the active batch into Recording to BIDS. Recording to BIDS validates the combined conversion plan, previews each proposed BIDS destination, and runs output preflight before any writes.

Validation consumes final explicit manifest assignments regardless of whether they came from canonical BIDS prefilling, user-defined mappings, fixed-value bulk edits, or individual edits. Preflight classifies recordings as new, already processed, conflicting, excluded, or unresolved. Existing outputs must never be silently overwritten, and only ready recordings may enter conversion.

Acceptance criteria

• Configuration can display the active manifest loaded from the workbench or from a saved file and apply dataset-wide settings without rewriting it.
• Recording to BIDS consumes the active manifest plus current Configuration as a conversion plan.
• Every included recording displays its proposed BIDS destination before conversion.
• Validation reports readiness independently for each recording.
• Validation depends only on saved explicit assignments and current configuration, not on rerunning discovery, prefilling, or mappings.
• Preflight distinguishes new outputs, matching existing outputs, and conflicting existing outputs.
• Excluded, unresolved, already processed, and conflicting recordings cannot enter the ready set.
• The conversion summary states exactly which recordings will run and which will be skipped.
• Deliberate replacement of an existing recording is unavailable.
• Automated coverage verifies both manifest-loading paths, collision handling, and that validation/preflight never mutates the manifest or output data.

Blocked by

• Ticket 7 — Save and load a versioned batch manifest.