# Real-sequence demultiplexing fixture

This fixture uses the first eight complete records from the pinned public
MAGeCK/Yusa `ERR376998_plasmid.fastq` excerpt. Six 50-base records retain their
first 40 experimental bases and complete original quality strings; only their
terminal 10 bases are replaced with a controlled barcode or variant. The
five-mismatch boundary control is shortened to one experimental base plus its
10-base barcode. The ambiguity control uses one neutral spacer plus its barcode
so the reverse-orientation search cannot introduce a second accidental match.

`TerminalA` and `TerminalB` are the first 10 bases of two real Yusa guides:

- CD244: `GCTCTGTTGC`
- ESCO2: `CGGAGCAGCA`

The two barcodes differ at all 10 positions. Records `A_M0` through `A_M5`
contain zero through five mismatches from TerminalA while remaining farther
from TerminalB. `B_M0` is an exact TerminalB record. `AMBIGUOUS_M5` is five
bases from both references and must remain unassigned.

The FASTQ SHA-256 is
`66A02C6ABA1DE0527072E482558C3583215D67852AA7D69E250C18D6A9CA666D`.
`ExpectedAssignments.tsv` is the independent assignment oracle for mismatch
allowances zero through five. Demultiplexed output must preserve each source
record's non-barcode sequence, orientation, header, and quality.
