Took me a while to find and reproduce the issue. The fix itself was simple.
I'm not a bot, I only enriched this PR summary with ALL context information.

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Changes:

• Fixed poetry-env plugin failure with in-project virtual environments

  • Handle case where poetry env info --path returns "." instead of full path when virtualenvs.in-project = true
  • Convert "." to "$PWD/.venv" to locate the correct virtual environment directory
  • Add safety check to ensure activate script exists before attempting to source it
  • Maintain backward compatibility with existing Poetry setups (centralized virtual environments)

• Root cause: When Poetry is configured with virtualenvs.in-project = true, the command poetry env info --path returns "." instead of the full path to the virtual environment. This causes the plugin to attempt sourcing "./bin/activate" which fails with "no such file or directory".

• Solution: Check if the returned path is "." and convert it to the proper in-project virtual environment path "$PWD/.venv", then verify the activate script exists before sourcing.

Comprehensive Issue Analysis:

When This Issue Occurs:

Poetry Version Impact:

• Poetry 1.8.5 & 2.0.1: ❌ Return "." (affected by bug)
• Poetry 2.1.3+: ✅ Return full paths (bug fixed)

Specific Scenarios That Trigger the Bug:

1. Documented Poetry -C Bug (GitHub Issue #9247)

   • Using poetry -C <directory> returns relative paths instead of absolute
   • Affects monorepo workflows and automation tools

2. Broken/Transitional Virtual Environment States

   • Empty .venv directory exists but is incomplete
   • Interrupted Poetry operations (e.g., during poetry install)
   • Race conditions in complex development environments

3. Sophisticated Development Setups

   • Monorepos with git worktrees
   • Runtime managers like mise/asdf with nested configurations
   • Concurrent operations between automation tools and shell hooks

How to Reproduce:

Method 1: Create broken venv state

cd your-poetry-project
rm -rf .venv && mkdir .venv
poetry env info --path  # Returns "." instead of full path

Method 2: Monorepo + git worktree setup

# In sophisticated setups with mise, git worktrees, and nested configs
# The issue occurs during directory navigation when:
# 1. Mise enter hooks run poetry commands
# 2. Oh My Zsh chpwd hooks trigger simultaneously
# 3. Race conditions cause Poetry to return "." temporarily

Error Reproduced:

_togglePoetryShell:source:20: no such file or directory: ./bin/activate

Why This Fix "Can't Hurt" Even Though It's an Edge Case:

Defensive Programming Benefits:

1. Zero Risk: The fix only activates when Poetry returns exactly "." - a clearly broken state
2. Backward Compatible: No impact on working Poetry setups (centralized or in-project)
3. Future-Proof: Protects against Poetry regressions or edge cases in newer versions
4. Graceful Degradation: Adds safety checks that benefit all users

Real-World Impact:

• Affects Advanced Users: Those using sophisticated development environments
• Critical When It Happens: Completely breaks virtual environment activation
• Hard to Debug: Users get cryptic error messages without clear solutions
• Growing Relevance: More developers using monorepos, worktrees, and automation tools

Maintenance Perspective:

• Low Maintenance: Simple, focused fix with clear logic
• Self-Documenting: Code comments explain the exact scenario being handled
• Testable: Easy to verify the fix works and doesn't break existing functionality
• Educational: Helps other developers understand Poetry's edge cases

Other comments:

Related PRs:

• Fixes the same issue as closed PR fix(poetry-env): poetry info --path cannot find directory '/bin/activate' because... #12270: Previous attempt used poetry shell instead of fixing the path issue, but was rejected by maintainers for "changing too much the way it works" and "spawning a new shell is not desirable"
• Complements closed PR Fixed poetry-env plugin for Poetry >=2.0.0 #12985: That PR addressed Poetry 2.0+ detection but was closed when author deleted their repository (not rejected by maintainers)
• Builds upon successful PRs: fix(poetry-env): switch venv between poetry dirs #12804, fix(poetry-env): only run deactivate if needed #12701, feat(poetry-env): support changing between two venv dirs #12346, fix(poetry-env): activate only if env exists #12301 - all made incremental improvements to poetry-env plugin

Why This Approach is Better:

• Maintains existing behavior: Unlike fix(poetry-env): poetry info --path cannot find directory '/bin/activate' because... #12270, this doesn't change the fundamental mechanism
• Minimal and targeted: Only fixes the specific path resolution issue
• Backward compatible: Works with both in-project and centralized virtual environments
• Follows maintainer feedback: Addresses @carlosala's concern about keeping the existing approach

Technical Details:

This issue commonly affects users who:

• Use Poetry's in-project virtual environments (virtualenvs.in-project = true) - a recommended setup
• Work with monorepos or git worktrees
• Have migrated from centralized to in-project virtual environments
• Use automation tools (mise, asdf, etc.) with complex project structures

Testing:

• ✅ Tested with Poetry 1.8.5, 2.0.1 (reproduces issue), and 2.1.3 (issue fixed)
• ✅ Verified fix works with both in-project (virtualenvs.in-project = true) and centralized virtual environments
• ✅ Confirmed backward compatibility with existing setups
• ✅ Successfully reproduced original error and verified fix resolves it
• ✅ Added safety checks to prevent similar issues in the future

Poetry Version Analysis:

While Poetry 2.1.3+ fixes the underlying bug, this defensive programming approach is valuable because:

• Many users still run older Poetry versions
• The fix protects against potential regressions
• It handles edge cases that might still exist in complex environments
• Zero cost for users with working Poetry installations

The fix is minimal, backward-compatible, and follows the existing code style and patterns used in the plugin.