feat: add depth parameter for planning thoroughness

Adds depth setting (quick/standard/comprehensive) to control how many
phases and plans get created. Tasks per plan stays constant at 2-3.

- Quick: 3-5 phases, 1-3 plans each
- Standard: 5-8 phases, 3-5 plans each
- Comprehensive: 8-12 phases, 5-10 plans each

Depth increases plan COUNT, never plan SIZE. More plans = more
thoroughness with same quality per plan.

Files changed:
- new-project.md: depth question after mode
- config.json: depth field added
- create-roadmap.md: depth-aware phase guidance
- plan-phase.md: depth-aware plan splitting
- scope-estimation.md: depth calibration section
- create-milestone.md: removed hardcoded 3-6 limit
- new-milestone.md: removed hardcoded 3-6 limit
- roadmap.md template: depth-aware guidance

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

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

commands/gsd/new-milestone.md

@@ -32,7 +32,7 @@ Milestone name: $ARGUMENTS (optional - will prompt if not provided)
 1. Load project context (STATE.md, ROADMAP.md, MILESTONES.md)
 2. Calculate next milestone version and starting phase number
 3. If milestone name provided in arguments, use it; otherwise prompt
-4. Gather phases (3-6 recommended):
+4. Gather phases (per depth setting: quick 3-5, standard 5-8, comprehensive 8-12):
    - If called from /gsd:discuss-milestone, use provided context
    - Otherwise, prompt for phase breakdown
 5. Detect research needs for each phase
@@ -48,7 +48,7 @@ Milestone name: $ARGUMENTS (optional - will prompt if not provided)
 <success_criteria>
 
 - Next phase number calculated correctly (continues from previous milestone)
-- 3-6 phases defined with clear names
+- Phases defined per depth setting (quick: 3-5, standard: 5-8, comprehensive: 8-12)
 - Research flags assigned for each phase
 - ROADMAP.md updated with new milestone section
 - Phase directories created

commands/gsd/new-project.md

@@ -230,7 +230,24 @@ Use AskUserQuestion:
   - "Interactive" — Confirm at each step
   - "YOLO" — Auto-approve, just execute
 
-Create `.planning/config.json` with chosen mode using `templates/config.json` structure.
+</step>
+
+<step name="depth">
+
+Ask planning depth preference:
+
+Use AskUserQuestion:
+
+- header: "Depth"
+- question: "How thorough should planning be?"
+- options:
+  - "Quick" — Ship fast, minimal phases/plans (3-5 phases, 1-3 plans each)
+  - "Standard" — Balanced scope and speed (5-8 phases, 3-5 plans each)
+  - "Comprehensive" — Thorough coverage, more phases/plans (8-12 phases, 5-10 plans each)
+
+**Depth controls quantity, not quality.** All depths use 2-3 tasks per plan. Depth determines how many plans get created—more depth means more plans, not bigger plans.
+
+Create `.planning/config.json` with chosen mode and depth using `templates/config.json` structure.
 
 </step>