Answers the 3 adoption questions (Plan-21 follow-up):
1) LEVEL SELECTION (4 packaging levels, packaging/levels.json):
- install.sh --level core|devkit; platform refused (preview service),
enterprise refused (future). Level recorded in .casan-level.
- casan init --level 1..4: L1=gate+Plan-20 hooks only; L2=+CI+domain-pack;
L3=L2 base+preview note; L4=refused. New `casan level show|set`.
- levels.json core now includes adapters/ + schemas/ + install scripts.
2) EXISTING SHELLS (agents/skills): init MERGES Plan-20 hooks into an existing
.claude/settings.json and .codex/{hooks.json,config.toml} idempotently
instead of clobbering — preserves the project's own hooks/agents/skills and
unrelated keys. Re-running never duplicates the CASAN hook.
3) NO RE-INDEX / NO SHELL REWRITE: init only adds config; it does not parse or
index code and does not rewrite the project shell.
Safety fixes after a test accidentally ran init in the real repo:
- launcher shim now SELF-LOCATES its install from its own path (no ambient
CASAN_HOME cross-talk).
- casan init REFUSES to adopt a CASAN source hub into itself (--force to
override), so the Plan-20 hooks can't block the developing agent.
- test always runs init inside throwaway dirs; +source-hub guard test.
hybrid-install-tests.sh: 41/41 PASS.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
