Prevent scope creep in discuss-phase command

Add explicit guardrails to ensure context gathering questions clarify
HOW to implement roadmap scope rather than suggesting WHAT to add.
Questions must never expand scope - if user adds scope, direct them
to update ROADMAP first instead.

Changes:
- Template: Replace "Secondary goals" with "Clarifications" (HOW, not WHAT ELSE)
- Workflow: Add CRITICAL block forbidding scope-expanding questions
- Workflow: Update decision gate to emphasize clarification over expansion
- Command: Add NO SCOPE CREEP rules

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

commands/gsd/discuss-phase.md

@@ -32,10 +32,15 @@ Phase number: $ARGUMENTS (required)
 4. Follow discuss-phase.md workflow:
    - Present initial context from roadmap
    - Analyze gaps in: objectives, constraints, risks, success indicators, codebase context
-   - Ask 2-4 questions about genuine gaps (skip what roadmap provides)
+   - Ask 2-4 CLARIFYING questions (never suggest additions or expansions)
    - Present decision gate (ready / ask more / let me add context)
    - Create CONTEXT.md using template
 5. Offer next steps (typically: plan the phase)
+
+CRITICAL - NO SCOPE CREEP:
+- Questions clarify HOW to implement roadmap scope, not WHAT to add
+- Never ask "should we also..." or "do you want to add..."
+- If user adds scope, suggest updating ROADMAP first instead
 </process>
 
 <success_criteria>