fix: warn when planning without user context or discussing after plans exist

Closes #253 — plans were silently created without CONTEXT.md, and
discuss-phase didn't warn when plans already existed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

get-shit-done/workflows/discuss-phase.md

@@ -147,7 +147,23 @@ If "Update": Load existing, continue to analyze_phase
 If "View": Display CONTEXT.md, then offer update/skip
 If "Skip": Exit workflow
 
-**If doesn't exist:** Continue to analyze_phase.
+**If doesn't exist:**
+
+Check `has_plans` and `plan_count` from init. **If `has_plans` is true:**
+
+Use AskUserQuestion:
+- header: "Plans exist"
+- question: "Phase [X] already has {plan_count} plan(s) created without user context. Your decisions here won't affect existing plans unless you replan."
+- options:
+  - "Continue and replan after" — Capture context, then run /gsd:plan-phase {X} to replan
+  - "View existing plans" — Show plans before deciding
+  - "Cancel" — Skip discuss-phase
+
+If "Continue and replan after": Continue to analyze_phase.
+If "View existing plans": Display plan files, then offer "Continue" / "Cancel".
+If "Cancel": Exit workflow.
+
+**If `has_plans` is false:** Continue to analyze_phase.
 </step>
 
 <step name="analyze_phase">

get-shit-done/workflows/plan-phase.md

@@ -61,6 +61,18 @@ Use `context_content` from init JSON (already loaded via `--include context`).
 
 If `context_content` is not null, display: `Using phase context from: ${PHASE_DIR}/*-CONTEXT.md`
 
+**If `context_content` is null (no CONTEXT.md exists):**
+
+Use AskUserQuestion:
+- header: "No context"
+- question: "No CONTEXT.md found for Phase {X}. Plans will use research and requirements only — your design preferences won't be included. Continue or capture context first?"
+- options:
+  - "Continue without context" — Plan using research + requirements only
+  - "Run discuss-phase first" — Capture design decisions before planning
+
+If "Continue without context": Proceed to step 5.
+If "Run discuss-phase first": Display `/gsd:discuss-phase {X}` and exit workflow.
+
 ## 5. Handle Research
 
 **Skip if:** `--gaps` flag, `--skip-research` flag, or `research_enabled` is false (from init) without `--research` override.