GC Content & Sequence Composition Analyzer mechanism

Model scope

GC% is mathematically sound for canonical DNA or RNA bases, but the DNA/RNA input claim conflicts with the AT% output. Define sequence normalization, valid-symbol policy, empty-input behavior, and whether RNA reports AU% before release.

• GC%=(G+C)/total×100 is correct only when total is explicitly defined as the count of valid canonical nucleotides and G/C are counted case-insensitively.
• AT% is not correct for RNA sequences because RNA uses U rather than T; RNA requires AU%=(A+U)/total×100, or the instrument must restrict input to DNA.
• The specification does not define how invalid, ambiguous, gap, whitespace, or other characters affect total, counts, and percentages.
• The claimed sequence length stats have no formulas or definition beyond length; it is unclear whether length means raw input length or normalized valid-base length.

Units and conventions

• Percentages are expressed on a 0–100 scale, not as fractions from 0 to 1.
• total is assumed to be the number of canonical A, C, G, and T bases for DNA, or A, C, G, and U for RNA.
• Inputs are assumed to be normalized for case and whitespace before counting; this behavior is not specified.
• For the RNA test vector, literal AT% is shown to expose the ambiguity; the biologically appropriate complementary percentage is AU%.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "sequence": "ATGC"
  },
  "expected_outputs": {
    "gc_percent": 50,
    "at_percent": 50,
    "base_counts": {
      "A": 1,
      "T": 1,
      "G": 1,
      "C": 1
    },
    "length": 4
  },
  "working": "Count A=1, T=1, G=1, C=1, so total=1+1+1+1=4. GC count=G+C=1+1=2. GC%=2/4×100=50%. AT count=A+T=1+1=2. AT%=2/4×100=50%. Length=4."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specification does not define behavior for an empty sequence, causing GC% and AT% to require division by zero. It also does not define RNA U handling or the denominator policy for ambiguous symbols such as N, so different reasonable implementations can produce different outputs.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json