pi: add /bug prompt template for test-driven bug diagnosis

Author: juanibiapina

dotfiles/pi/.pi/agent/prompts/bug.md

@@ -0,0 +1,53 @@
+---
+description: Investigate and fix a bug with test-driven diagnosis
+---
+
+# Bug Fix
+
+Fix a bug using test-driven diagnosis. Write a failing test first, then fix it.
+
+## Bug Description
+
+$ARGUMENTS
+
+## Workflow
+
+### 1. Investigate
+
+Find the root cause before touching any code:
+
+- Read relevant source files — trace the execution path that triggers the bug
+- Check existing tests to understand intended behavior
+- Check recent git history for changes that may have introduced it
+- Narrow down to the specific code responsible
+- If the bug description is unclear, ask questions before proceeding
+- State the root cause clearly before moving on
+
+### 2. Reproduce
+
+Write a test that exposes the bug:
+
+- The test should encode the correct expected behavior
+- It must fail against the current code, proving the bug exists
+- Keep it minimal — test exactly the broken behavior, nothing else
+- Run the test and confirm it fails
+
+If the test passes, your understanding of the bug is wrong — go back to step 1.
+
+### 3. Fix
+
+Make the minimal change to fix the bug:
+
+- Fix only what's broken — don't refactor, don't clean up
+- Follow existing patterns in the codebase
+- Run the failing test and confirm it now passes
+- Run the full test suite to check for regressions
+
+### 4. Report
+
+Summarize:
+
+- Root cause
+- What the test covers
+- What was changed to fix it
+- Any related issues worth noting