From aca4e0b8c90c08ec2caca18f70875af70e0dc147 Mon Sep 17 00:00:00 2001
From: Ed_ <edwardgz@gmail.com>
Date: Sat, 20 Jun 2026 19:30:22 -0400
Subject: [PATCH] chore: TIER-2 READ
 conductor/code_styleguides/error_handling.md end-to-end before Phase 0

Acknowledges Rule #0 of the AI Agent Checklist (lines 809-940 of the
styleguide). Sections re-read for this track:
- 5 Patterns (Nil-Sentinel, Zero-Init, Fail-Early, AND over OR, Error
  Info as Side-Channel)
- Drain Points (5 patterns + 5 'NOT a drain point' anti-patterns)
- Boundary Types (third-party SDK, stdlib I/O, FastAPI)
- Broad-Except Distinction (the table classifying every catch site
  by what it does with the exception)
- AI Agent Checklist (5 MUST-DO + 7 MUST-NOT-DO + 3 boundary patterns)

Key principle applied to this track: 'error dropping is NOT a drain'
(the legacy wrapper def _x(): return _x_result(...).data defeats
the entire purpose of the Result[T] migration; the wrapper silently
swallows the error from _x_result).