Group repeated templates with source locators

Count repetition without discarding its source range.

Type: Build Languages: Rust, Python Stage: 2 of 4 Prerequisites: Basic functions, collections, JSON and the previous stages when applicable. Time: ~2 hours

What you build

Group by the pair (level, template). A group contains total count, first and last source line, and the first encountered original message. Sorted group keys make serialization stable. Digit normalization is a heuristic, not semantic equivalence.

Worked example

The 200-line burst contains 199 WARN retries and one ERROR disk-full message at line 138. Its retry group spans lines 1 through 200. The disk group has firstLine=lastLine=138.

Implement the contract

group(&[Record])->Vec<Group>; Group{level,template,count,first,last,example}. Return groups in lexical level/template order. Source ranges include gaps; they are not a claim that every intervening line belongs to the group.

Reject malformed input before producing a partial artifact. The tests include held-out records separate from the demonstration fixture.

Run your work

python3 scripts/project_test.py log-volume-reduction-lab --init /tmp/log-volume-reduction-lab-work
python3 scripts/project_test.py log-volume-reduction-lab --stage 2 --path /tmp/log-volume-reduction-lab-work --strict

Initialization copies cumulative scaffolding without replacing your work. Implement the TODO functions in the first-stage starter; later-stage starter notes describe the new behavior. Tests import the learner workspace. Run the command in the README against your own input after passing the stage.

Inspect and extend

Create two different messages that collapse to the same digit template and discuss the diagnostic evidence this loses.

Go standard library and Node standard library. All fixtures and implementations are original.