Summary

Document how to add log emissions when porting code from pnpm, so future
ports — especially AI-generated ones — don't silently skip events and
recreate the coverage gap we're fixing.

Scope

• Add a "Reporting" section to AGENTS.md (or a subsection in
  CODE_STYLE_GUIDE.md, whichever fits the surrounding structure better)
  covering:
  • Finding upstream emissions. Patterns to grep for in pnpm/pnpm:
    globalLogger.<channel>.<level>(...),
    logger.<level>({ name: 'pnpm:<channel>', ... }), and direct
    streamParser.write(...) calls.
  • Channel mapping. How upstream name: 'pnpm:<channel>' maps to a
    LogEvent variant in crates/reporter. Include the canonical list
    and where to look it up.
  • Generic threading convention. Per Use pnpm's @pnpm/cli.default-reporter for terminal output (via NDJSON) #344's architecture: any function
    that emits takes R: Reporter and calls R::emit(...). Production
    callers turbofish at the entry point. Same shape as the DI pattern in
    Refactor and document the dependency injection pattern for tests #339.
  • Where to put the emit calls. Match the upstream call site —
    typically immediately before or after the side effect the event
    describes. Keep ordering consistent with pnpm so the rendered output
    stays identical.
  • Testing. Declare a recording fake inside the #[test] fn per
    Refactor and document the dependency injection pattern for tests #339, recording into a static Mutex<Vec<LogEvent>> declared in the
    same body; assert against the captured sequence.
  • What not to do. Don't reformat upstream messages, don't invent new
    channels, don't emit at higher granularity than pnpm (the JS reporter
    expects pnpm's event cadence).
• One worked example: pick a small ported pnpm function that emits one or
  two log events, show the before/after Rust diff, link the upstream
  permalink (pinned SHA per CLAUDE.md), and reference the test fake.
• Add a pointer from the cardinal-rule section of AGENTS.md: matching
  pnpm's behavior includes its log emissions — see the new section.

Acceptance criteria

• A reviewer can read the new section and answer, given an upstream pnpm
  function: which log events does it emit, where do those map in pacquet,
  where do the emit calls go, and how do I test them.
• The worked example builds and matches the canonical reporter shape from
  feat(reporter): implement the reporting engine (NDJSON + Reporter trait) #345.
• AGENTS.md's cardinal-rule section explicitly mentions log emissions as
  part of what "match pnpm" entails.

Depends on

• feat(reporter): implement the reporting engine (NDJSON + Reporter trait) #345 (the reporter must exist so the convention can reference real types
  and call sites instead of pseudocode).

Parent

Design: #344.