serialpump: 17 surviving mutants, 58.5% efficacy (worst in tree)

open   by a73x

Labels: backlog

[claude 2026-08-22] From the mutation baseline. serialpump has the worst efficacy in the tree: 24 killed, 17 lived, 58.54%. Mutant coverage is 100% — every mutable line IS executed by a test, so this is purely missing assertions, not missing tests.

Surviving mutants:

```
LIVED CONDITIONALS_NEGATION at serialpump.go:185:13
LIVED ARITHMETIC_BASE at serialpump.go:194:17
LIVED CONDITIONALS_BOUNDARY at serialpump.go:207:16
LIVED CONDITIONALS_NEGATION at serialpump.go:207:16
LIVED ARITHMETIC_BASE at serialpump.go:207:20
LIVED ARITHMETIC_BASE at serialpump.go:218:17
LIVED ARITHMETIC_BASE at serialpump.go:214:19
LIVED CONDITIONALS_NEGATION at serialpump.go:233:13
LIVED CONDITIONALS_BOUNDARY at serialpump.go:245:8
LIVED CONDITIONALS_BOUNDARY at serialpump.go:278:43
LIVED CONDITIONALS_BOUNDARY at serialpump.go:311:29
LIVED CONDITIONALS_NEGATION at serialpump.go:314:57
LIVED CONDITIONALS_NEGATION at serialpump.go:319:10
LIVED CONDITIONALS_NEGATION at serialpump.go:326:9
LIVED INCREMENT_DECREMENT at serialpump.go:363:10
LIVED CONDITIONALS_BOUNDARY at serialpump.go:404:9
LIVED CONDITIONALS_NEGATION at serialpump.go:407:11
```

Clusters worth reading together: the 207/214/218 arithmetic block, and the 311-326 conditional run.

Rerun: `make mutate PKG=./internal/agent/serialpump` (89s).