zfinix/aster/build-triage

Build triage

1. Fix the first error, not the last. Everything after the first error is

usually cascade. cargo build 2>&1 | grep -m1 -B1 -A6 "^error".

1. Exit code 0 can still be a failure. The exit code of a pipeline belongs

to its last stage: cargo build 2>&1 | tail -3 reports tail's success. Trust the output text (error[, FAILED, panicked) over the code.

1. Bound the output. | tail -20 for verdicts (test runners put the

verdict last), | head -30 for first errors, --stat for diffs. Never dump a full build log.

1. Never escalate a timeout. A command that timed out will time out again

with a bigger budget. The exception is work that is long by nature (an eval, a full suite): run it with background:true, see long-running-work. Kill leftovers (pkill -f cargo), then narrow: one package, one test, one file. cargo check -p one-crate beats a 10 minute workspace build.

1. Label pipeline stages so partial output says where it died:

echo "=== build ===" && cargo check 2>&1 | tail -3 && echo "=== test ===" && cargo test 2>&1 | tail -5

1. Filter noise to signal. A hundred identical warnings hide one error:

2>&1 | grep -E "^(error|FAILED|thread)" | head -10.