docs(workflow): report-only-mode rules + retail-faithful-port guardrail in CLAUDE.md

Three new bullets, all evidence-driven from /insights:

"Only stop and wait for the user when":
- Request is an investigation/audit/analysis/review/report-only — no edits
  or diagnostic drops until the user approves a fix. Use the /investigate
  skill (local at .claude/skills/investigate/SKILL.md, gitignored).
- A referenced commit/path/branch/doc doesn't exist where the user said
  it would — ask one short question; don't go hunting across branches.
  Prevents the N.5-handoff-style 30-min wrong-branch exploration.

"What NOT to do":
- Don't replace working retail-faithful logic with a modern redesign
  without explicit approval. Cites the 267 min remote-entity rewrite +
  sky-fog shader speculation both reverted in full. Retail-faithful
  first; "cleaner" second.

The /investigate skill itself stays local (option 3 — not committed).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -189,6 +189,14 @@ retail. Everything else is your call.
   files, reverting multiple commits)
 - Memory or committed history shows a clear user preference you're about to
   diverge from
+- **The request is an investigation, audit, analysis, review, or "report-only"**
+  — no edits, no writes, no diagnostic code drops until you've delivered the
+  report and the user explicitly approves a fix. Use the `/investigate` skill
+  (`.claude/skills/investigate/SKILL.md`) to enter this mode cleanly.
+- **A referenced commit, file path, branch, or doc doesn't exist** where the
+  user said it would. Ask one short question; don't go hunting across branches
+  or worktrees. A 1-line clarification beats 30 minutes of wrong-branch
+  exploration.
 
 **Things you should just do without asking:**
 
@@ -348,6 +356,14 @@ isn't enough, attach cdb to a live retail client (Step -1).**
   context of the existing code it's modifying. The first animation
   sequencer integration was done by a subagent that didn't understand
   the transform pipeline — it broke everything.
+- **Do not replace working retail-faithful logic with a modern redesign**
+  without explicit user approval. Two campaigns (267 min remote-entity
+  prediction+rubber-band replacing hard-snap; speculative shader edits in
+  the sky-fog work) had to be reverted in full because the redesign
+  regressed behavior the original port had right. When you see "I could
+  simplify this with X" on a retail-port, flag the tradeoff and ask
+  before deleting the existing path. Retail-faithful first; "cleaner"
+  second.
 
 ### Phase completion checklist: