Add selectable CASAN IDE integrations

packages/casan-devkit/templates/codex/README.md

@@ -1,9 +1,9 @@
 # CASAN Codex adoption template (Plan-20)
 
-Drop `hooks.json` → `.codex/hooks.json` and merge `config.toml` into
-`.codex/config.toml` in the target repo (the installer does this). It wires the
-Codex lifecycle hooks to the CASAN agentic bridge via the thin renderer
-`packages/casan-harness/adapters/codex/codex_hook.py`.
+`casan init --client codex` merges `hooks.json` into `.codex/hooks.json`. Each
+handler calls `.casan/casan-hook.py`, which resolves and verifies the pinned
+global harness before dispatching the Codex adapter. No custom `[casan]` TOML
+keys are required.
 
 Important Codex-specific facts (Spike-20 §4.2):
 
@@ -21,6 +21,6 @@ Important Codex-specific facts (Spike-20 §4.2):
   disable them and set `CASAN_AGENTIC_INTEGRATION_MODE=managed_hook` through the
   managed environment (not the committed config).
 
-The command contract is stable (stdin JSON → exit 0 allow / exit 2 block); the
-exact Codex payload key names are pinned during the Wave-3 payload spike, which
-is why `codex_hook.py` reads several field aliases defensively.
+The command shape follows current Codex hooks: nested command handlers,
+`timeout` in seconds, `continue`/`stopReason` for turn events, and exit 2 for a
+denied `PreToolUse`. The adapter reads documented fields plus defensive aliases.