[JacobStephens2]

Summary

Add an application-independent OTLP JSON Lines reader and writer for log records
and spans, ready for Session-trace recording. No new run-time packages.

src/otlp_jsonl.rs          typed requests; one signal per stream; flush each line
src/otlp_jsonl/value.rs    all attribute types, base64 bytes, special doubles
src/otlp_jsonl/integer.rs  exact decimal/exponent integer decoding
src/otlp_jsonl/fixtures/   official examples and local Collector configuration

Closes #982

Evidence

• Before: the review's exact regressions reproduced a finite double changing
  from 8.971135692166839e-150 to 8.97113569216684e-150, and rejected
  timeUnixNano: "4.2e1".
  After: both exact selectors pass; both regression tests are retained.

  cargo test --bin thirdshift otlp_jsonl::tests::finite_double_reads_back_without_changing_bits -- --exact
  cargo test --bin thirdshift otlp_jsonl::tests::reader_accepts_protojson_integer_spellings_without_rounding -- --exact

• All 13 codec tests pass in isolation. Official protocol types verify both
  signals, and the specification's log, event, trace and JSON Lines examples
  preserve their values.

• Collector v0.163.2 read and re-exported two log requests and two span
  requests with identical JSON values. Result and reproduction steps are in
  docs/research/otlp-file-writer.md.

• cargo check and cargo clippy --all-targets -- -D warnings pass. The normal
  dependency package set is identical to issue-700.

• /usr/bin/time -p scripts/affected-tests issue-700 selected cargo nextest run:
  2,236 passed, 2 skipped, exit 0. Wall time 2,024.49 seconds, including
  compilation and the initial build-lock wait (test execution: 1,954.491 seconds).

Test seams

• The standalone otlp_jsonl module's typed requests, Writer and Reader: inspect emitted JSON, decode with OpenTelemetry's official protocol types, and read back through the same public interface. Specification fixtures supply independent expected values.
• One-time interoperability: the Collector's otlp_json_file receiver reads files emitted through that interface and its file exporter writes the records and spans back.

Review

Reviewed against fixed point issue-700 (cd7119f), with independent Standards
and Spec reviewers. Standards' one P3 duplication finding was addressed; Spec's
two P2 behavior findings were reproduced with their exact commands, fixed and
verified with the same commands. Both axes read all 17 changed files, including
the follow-up changes. No generated-output exclusions or unread changed files.

Unaddressed findings

Standards

None.

Spec

None.

Merge Danger

Door: two-way

The codec can be removed without a data migration.

Blast Radius: serialization

serde_json precision features apply across the binary; full Rust validation
covers existing consumers. The official OpenTelemetry dependency is test-only.

Built with codex · gpt-6.1-sol · xhigh