plan-batches

name	plan-batches
description	Use when the user has a manifest and needs to group files into disc-sized batches without splitting any file across discs.

Plan Batches

Group files from manifest.json into batches that each fit on one disc. Uses first-fit-decreasing by size. Files are never split across discs. Warns hard if any single file exceeds disc capacity.

When to use

• After scan-source, before build-iso or burn-disc.
• Whenever the user asks "how many discs will this take".

Inputs to gather

• Manifest path (default: $WORKSPACE/manifest.json).
• Media type — one of: m-disc-25 (25000 MiB), bd-r-25 (25000), bd-r-50 (50000), dvd-dl-8.5 (8500), dvd-4.7 (4700).
• Target batch size — default 24000 MiB (leaves headroom on 25 GB media). Override per media type as appropriate.

Procedure

1. Load manifest. Sort entries descending by size.
2. For each file, place it into the first existing batch with enough remaining capacity; otherwise open a new batch.
3. If any single file size > media capacity, abort with a clear error listing offending files. Suggest splitting via split or storing as a tar-stream archive.
4. For each batch NN (zero-padded, starting at 01):
   • Write $WORKSPACE/batches/disc-NN/filelist.txt — one absolute source path per line.
   • Write $WORKSPACE/batches/disc-NN/filelist-graftpoints.txt — archive_path=source_path per line, suitable for xorriso -graft-points.
5. Write $WORKSPACE/plan.json summarising disc count, per-disc total size, file count, and fill ratio.
6. Print a one-line-per-disc table: disc-NN files=... size=... MiB fill=...%.

Output / side effects

• $WORKSPACE/batches/disc-NN/filelist.txt and filelist-graftpoints.txt per disc.
• $WORKSPACE/plan.json.
• Stdout disc plan summary.

Safety / constraints

• Never modify source files.
• Refuse to plan if media capacity is unset or zero.