Add Linear issue worktree workflow

config/pi/prompts/issue.md

@@ -0,0 +1,19 @@
+---
+description: Implement a Linear issue in an isolated Git worktree using a child Pi agent
+argument-hint: "<ISSUE-ID>"
+---
+Work on Linear issue: $ARGUMENTS
+
+Act only as the parent orchestrator:
+
+1. Validate that the argument identifies exactly one Linear issue.
+2. Retrieve the issue through the Linear MCP server. Include relations, comments, attachments, or linked context when they affect implementation.
+3. Read and understand the issue before starting the worker.
+4. Extract its title, description, URL, and explicit or reasonably inferred acceptance criteria.
+5. Call `run_issue_in_worktree` exactly once with that structured issue context.
+6. Let the child Pi agent perform every repository modification, validation command, and local commit.
+7. The child must not push or create a pull request; publication happens only after explicit user review.
+8. Do not edit files or run implementation commands in the parent checkout.
+9. When the child finishes, summarize its status, branch, worktree path, local commit, checks, blockers, and the command for resuming its Pi session.
+
+Stop and explain the problem instead of starting the worker when the issue cannot be retrieved or its requirements are too ambiguous to delegate safely.