Enhance write-tests command and testing guidelines based on AAR feedback.

Command improvements:
- Add WebFetch to allowed tools for guide access
- Add mandatory pre-flight check to verify guide accessibility
- Add step to check for existing tests to avoid duplication
- Add tests/README.md generation when missing
- Add final report requirement for technical conflicts and resolutions

Testing guide enhancement:
- Add cross-platform testing strategy using pathlib.Path.resolve() and
  .samefile() for Windows compatibility

These changes address gaps identified in first trial run where test guide
wasn't properly accessed and platform-specific issues weren't considered.

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

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

Author: emcd

documentation/common/tests.rst

@@ -244,6 +244,9 @@ Testing Strategy by Code Type
    * - **Abstract Methods**
      - ``# pragma: no cover``
      - Apply to ``NotImplementedError`` lines only
+   * - **Cross-Platform**
+     - ``pathlib.Path`` with ``.resolve()`` and ``.samefile()``
+     - Use ``Path.resolve()`` to unfurl symlinks; ``.samefile()`` for comparisons on Windows
 
 Development Environment
 ===============================================================================

template/.auxiliary/configuration/claude/commands/write-tests.md

@@ -1,5 +1,5 @@
 ---
-allowed-tools: Bash(hatch --env develop run:*), Bash(git status), Bash(git log:*), Bash(echo:*), Bash(ls:*), Bash(find:*), LS, Read, Glob, Grep, Write, Edit, MultiEdit
+allowed-tools: Bash(hatch --env develop run:*), Bash(git status), Bash(git log:*), Bash(echo:*), Bash(ls:*), Bash(find:*), LS, Read, Glob, Grep, Write, Edit, MultiEdit, WebFetch
 description: Write comprehensive tests following project testing guidelines and improve coverage
 ---
 
@@ -79,9 +79,24 @@ following occur:
 
 Execute the following steps for test requirements: `$ARGUMENTS`
 
+### 0. Pre-Flight Verification
+**MANDATORY - Verify access to test-writing guide:**
+
+Use WebFetch to access and confirm you can read the complete testing guidelines:
+```
+https://raw.githubusercontent.com/emcd/python-project-common/refs/heads/master/documentation/common/tests.rst
+```
+
+**CRITICAL**: You MUST successfully access and read the guide before proceeding. If WebFetch fails, HALT and consult with the user.
+
 ### 1. Code Analysis Phase
 Examine the target code to understand testing needs:
 
+**Check for existing related tests to avoid duplication:**
+- Search for existing test files covering target modules
+- Review test coverage reports for current state
+- Identify gaps rather than recreating existing tests
+
 **For each target file:**
 - Read the source code to understand public API
 - Identify functions/classes that need testing
@@ -93,6 +108,11 @@ Determine appropriate test organization and categories:
 
 **Review existing test structure and plan test numbering following project conventions.**
 
+**If tests/README.md is missing, create it with:**
+- Test module numbering scheme specific to the package
+- Rationale for any use of patch or other exceptions to standard patterns
+- Project-specific testing conventions and fixtures
+
 **Test Categories to Include:**
 - **Basic Functionality Tests (000-099):** Happy path scenarios, input validation, basic error conditions
 - **Feature-Specific Tests (100+ blocks):** Each public function/class gets its own 100-block with normal usage patterns, edge cases, and error handling
@@ -180,3 +200,12 @@ Tests are complete when:
 
 **Note**: Always run full validation (`hatch --env develop run testers && hatch
 --env develop run linters`) before considering the task complete.
+
+## Final Report
+
+Upon completion, provide a brief report covering:
+- Coverage improvements achieved (before/after percentages)
+- Any technical conflicts encountered (e.g., dataclass/protocol issues, __slots__ conflicts)
+- How any conflicts were resolved or worked around
+- Pragma directives applied (# pragma: no cover, # pragma: no branch) and rationale
+- Any deviations from standard patterns and justification