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the two chimera measurements land where measurements live - #497

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lhqing merged 2 commits into
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docs/land-chimera-research-407-408
Aug 22, 2026
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lhqing merged 2 commits into
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docs/land-chimera-research-407-408

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@lhqing lhqing commented Aug 22, 2026

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Two research notes were written for closed wayfinder tickets and never reached main — they have
been sitting on their own branches since 2026-08-14, so the map that consumed them cites primary
sources nobody can read from a checkout.

Both commits are cherry-picked unchanged from research/chimera-offline-detection and
research/star-on-a-chimera, authorship and message intact. Docs only — no src/, no tests/.
docs/research/** is in markdownlint's ignores and mkdocs' exclude_docs, so neither doc check
reaches these files; the gate is green.

Closes nothing — #406/#407/#408 are already closed. This lands the evidence they produced.

🤖 Generated with Claude Code

lhqing and others added 2 commits August 22, 2026 16:12
…eel already ships

Measurement for #407, under map #406. `chimera.split_name` plus `metadata.lookup_assembly`
answer "is this name a chimera's, and of what?" with no read of the reference store and no
network — but `Genome.components` says the record and never the table is the real test, and
liulab-genome ships a test proving `ce11_ecHT115` seeded from somebody's FASTA is not a
chimera. The offline predicate is about the NAME, it is capped at the seven rows the table
ships, and the pin in this repo predates `chimera.py` entirely.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
…and not the aligner

Research for #408 under map #406. STAR 2.7.11b read from source: a window is
confined to one chromosome, so no proper pair spans two components; NH and MAPQ
are both functions of nTrOutSAM, the chimera-wide reported-locus count;
outFilterMultimapNmax is applied to that same count, so a read with 9 host and 2
contaminant loci is dropped at the default of 10.

The load-bearing claim behind the map's standing decision 2 survives in substance
and fails twice. STAR reports every locus within outFilterMultimapScoreRange
(default 1) of the best, not only the best, so a read beating its cross-species
hit by one point still carries NH:i:2 MAPQ:3. And map/star-umi passes
--outSAMmultNmax 1, so its BAM holds one alignment record per template and
"spans more than one component" is not observable in it at all.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Copilot AI lite review requested due to automatic review settings August 22, 2026 20:14

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@lhqing
lhqing merged commit 744ba10 into main Aug 22, 2026
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@lhqing
lhqing deleted the docs/land-chimera-research-407-408 branch August 22, 2026 20:16
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2 participants