# Thinking Tools for Phase 3

Use these during analysis. They are thinking aids, not a checklist — pick what fits.

## Boundary drawing

"What principle determines whether X belongs in our scope?"

Define the principle first, then audit every item against it. Items that fail → explicitly out of scope with documented reason.

Example: "Anything affecting whether a request succeeds → our scope. Anything affecting how data is represented → not our scope."

## Essential difference vs surface similarity

"What is the lifecycle / failure mode / mental model of each thing I'm comparing?"

Things that look alike may be fundamentally different. The analysis that distinguishes them is where real insight lives.

Example: packet loss, connection reset, and route blackhole all look like "request failed" — but their detection, recovery, and design implications are completely different.

## Ecosystem consensus

If the entire ecosystem does it one way and we're different, can we articulate why? If not, reconsider.

Works both ways: consensus validates ("no one combines HTTP+WS+upload → split is right") and consensus challenges ("every client supports cancellation → we must too").

## User-scenario-backward

Start from "who needs what when", not "what can we do". Map 3-5 concrete scenarios, list needed capabilities, compare against what exists. Gaps from scenarios are real gaps.

## Self-interrogation

After reaching a conclusion:
- "Am I confusing 'we built it' with 'users need it'?"
- "Is the problem the what or the tempo?"
- "What would I think seeing this for the first time?"
