merge: resolve conflicts with origin/main

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -78,6 +78,7 @@ gstack/
 ├── setup            # One-time setup: build binary + symlink skills
 ├── SKILL.md         # Generated from SKILL.md.tmpl (don't edit directly)
 ├── SKILL.md.tmpl    # Template: edit this, run gen:skill-docs
+├── ETHOS.md         # Builder philosophy (Boil the Lake, Search Before Building)
 └── package.json     # Build scripts for browse
 ```
 
@@ -192,6 +193,19 @@ Completeness is cheap. Don't recommend shortcuts when the complete implementatio
 is a "lake" (achievable) not an "ocean" (multi-quarter migration). See the
 Completeness Principle in the skill preamble for the full philosophy.
 
+## Search before building
+
+Before designing any solution that involves concurrency, unfamiliar patterns,
+infrastructure, or anything where the runtime/framework might have a built-in:
+
+1. Search for "{runtime} {thing} built-in"
+2. Search for "{thing} best practice {current year}"
+3. Check official runtime/framework docs
+
+Three layers of knowledge: tried-and-true (Layer 1), new-and-popular (Layer 2),
+first-principles (Layer 3). Prize Layer 3 above all. See ETHOS.md for the full
+builder philosophy.
+
 ## Local plans
 
 Contributors can store long-range vision docs and design documents in `~/.gstack-dev/plans/`.