[mremond]

Why

The opt-in shutdown probe failed on every run of main: its packet demo case expected map keys in source order, but Nera prints maps of up to 32 keys in atom-table order.

What changed

• The probe reads the packet demo's two output lines as Erlang terms and compares each map as a set of entries, so key order no longer matters.
• Every line, key and value must still be present, with the same spacing; a missing or cut line, a changed value, or a repeated or extra key fails.
• Negative controls run when the probe starts, so the comparison cannot quietly become lenient.
• The contributing guide says which part of the probe's output may vary.

Before and after

Before: On main the probe passed the first four programs, then stopped with "incomplete/unexpected output" on the packet demo, whose output was complete and correct.

After: The probe passes all ten cases (five programs, two scheduler settings) and still fails when the packet demo's output is incomplete or wrong.

Only an opt-in test script and the contributing guide change; nothing a person using Nera sees changes.

Checked

• Main's probe on a release build of main, macOS arm64: Stops on the packet demo case: the output lists protocol before version
• Changed probe on the same build, ten runs in a row: 10 of 10 runs pass all 10 cases; medians 0.3 to 2.5 ms; the packet demo printed the same text in all 600 samples
• Changed probe with the demo altered to print one packet, a different ttl, or an extra map key: Each run fails on the packet demo case with incomplete/unexpected output
• The probe's built-in negative controls: Pass: reordered keys match; nine broken outputs are rejected

How it was checked

cargo build --release --locked -p nera-runtime, then -p nera: passed

python3 scripts/test-native-shutdown.py at main's version: exit 1 on the handler case

python3 scripts/test-native-shutdown.py at this version: exit 0 on 11 runs (one, then ten in a row), 10 of 10 cases within the 5 ms budget each time

Same probe with demo/serverless/handler.erl temporarily altered three ways (not committed): exit 1 each time, on the handler case

HANDLER_OUTPUT is byte-identical to the previous expected string

python3 scripts/ci/changes.py on the changed files: every CI job runs, since the probe script has no rule of its own

Risk

Risk above low: Novelty, medium — A small new reader for printed Erlang maps, tuples, atoms and integers

Full risk assessment

Dimension	Level	Why
Blast radius	low	One opt-in test script and one paragraph of the contributing guide
Behavior	low	Fixes a probe that failed on every run; no Nera behavior changes
Undo	low	Revert and done
Evidence	low	Probe run end to end before and after, plus three altered-demo runs that fail
Sensitivity	low	None
Novelty	medium	A small new reader for printed Erlang maps, tuples, atoms and integers
Dependencies	low	Standard library only