chore(commands): add auto-linking for blocks/relates-to/subtask relations

create-story: Step 7 prompts for issue links and auto-detects IDs in description.
fix-defect: Step 3b scans for referenced IDs; Step 7b prompts for post-push links.
split-story: Step 6b adds inter-subtask blocking chains; Step 6c links external issues.
All commands now use content-based project routing (not parent inheritance).

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

.claude/commands/split-story.md

@@ -59,11 +59,15 @@ Rules:
 - Definition of Done: adjust per subtask — not all subtasks need the same criteria (e.g. a research spike has different DoD than an implementation task).
 - Keep description short — one paragraph max.
 
-## Step 5 — Determine Project
+## Step 5 — Determine Project per Subtask
 
-Inherit project from parent story (`$ARGUMENTS`):
-- If parent is `NCWF-*` → subtasks go in `NCWF`
-- If parent is `NCS-*` → subtasks go in `NCS`
+Assign each subtask's project based on its content — do **not** inherit blindly from parent:
+
+- Backend code (game engine, bots, API, services, coordinator) → `NCS`
+- Frontend code (UI, UX, web app) → `NCWF`
+- Kubernetes, pipelines, CI/CD, DB setup, infrastructure → `NCI`
+
+If a subtask's project is ambiguous, ask the user before creating it.
 
 ## Step 6 — Create Subtasks
 
@@ -75,8 +79,31 @@ For each subtask call `mcp__youtrack__create_issue` with:
 
 Then call `mcp__youtrack__link_issues` to link each created subtask to `$ARGUMENTS` with relation `subtask of`.
 
+## Step 6b — Inter-Subtask Links
+
+If subtasks must be done in sequence (one depends on output of another), add ordering links:
+- For each dependency pair call `mcp__youtrack__link_issues` with relation `is blocked by` (subtask B is blocked by subtask A).
+
+Ask the user to confirm sequencing before adding these links:
+
+> Do any subtasks have ordering dependencies? (e.g. "Implement X must come before Add tests for X")
+
+## Step 6c — External Links
+
+Scan `$ARGUMENTS` description and implementation notes for any referenced issue IDs not already linked. For each:
+
+| Situation | Relation |
+|-----------|---------|
+| Parent story blocks another epic/story | `blocks` |
+| Story depends on another epic completing | `is blocked by` |
+| Related story in same domain | `relates to` |
+| This story duplicates or supersedes | `duplicates` |
+
+Suggest links to the user and call `mcp__youtrack__link_issues` on confirmation.
+
 ## Step 7 — Report
 
 List all created subtask IDs and summaries.
+List all links created (subtask-of, blocking chains, external).
 Display parent story link.
 Ask if any subtask needs further splitting.