## Description
Foundry sessions launched through `headroom wrap claude` currently
receive Headroom's generic `ENABLE_TOOL_SEARCH=true` default when the
user did not choose a tool-search mode. That can push Claude Code into a
deferred-tool request shape that Azure Foundry rejects with `API Error:
400 ... Some tools are not available`. This narrows the default-only
path so Foundry sessions stop forcing deferred-tool mode when the user
did not ask for it, while explicit overrides and the existing
non-Foundry custom-host behavior stay unchanged.
Closes#2464
## Type of Change
- [x] Bug fix (non-breaking change that fixes an issue)
- [ ] New feature (non-breaking change that adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [ ] Performance improvement
- [ ] Code refactoring (no functional changes)
## Changes Made
- add a Foundry-specific default for the no-override tool-search branch
- preserve explicit `--tool-search` values and pre-set
`ENABLE_TOOL_SEARCH` values exactly
- keep the generic non-Foundry default as `true`
- add focused helper-level regression coverage for Foundry defaulting
and adjacent negative space
## Testing
- [x] Focused unit tests pass (`uv run pytest
tests/test_cli/test_wrap_claude.py
tests/test_cli/test_wrap_claude_vertex_proxy_env.py
tests/test_issue_746_tool_search.py -q`)
- [x] Edited-file linting passes (`uv run ruff check
headroom/cli/wrap.py headroom/providers/claude/runtime.py
tests/test_cli/test_wrap_claude.py`)
- [ ] Type checking passes (`uv run mypy headroom`)
- [x] New tests added for new functionality when applicable
- [ ] Manual testing performed
### Test Output
```text
Command: uv run pytest tests/test_cli/test_wrap_claude.py tests/test_cli/test_wrap_claude_vertex_proxy_env.py tests/test_issue_746_tool_search.py -q
61 passed
Command: uv run ruff check headroom/cli/wrap.py headroom/providers/claude/runtime.py tests/test_cli/test_wrap_claude.py
All checks passed!
```
## Real Behavior Proof
- Environment: Windows, Python via `uv`, Foundry mode modeled through
the wrap helper inputs
- Exact command / steps: run the focused helper regression and
edited-file lint commands above
- Observed result: `61 passed`; `All checks passed!`; Foundry mode
without an override writes `ENABLE_TOOL_SEARCH=false`, while explicit
overrides, existing values, blank handling, and the non-Foundry default
remain covered
- Not tested: live Azure Foundry tenant run
## Review Readiness
- [x] I have performed a self-review
- [x] This PR is ready for human review
## Checklist
- [x] My code follows the project's style guidelines
- [x] I have performed a self-review of my code
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] I have updated the CHANGELOG.md if applicable
## Additional Notes
`CHANGELOG.md` stays untouched because Headroom generates release notes
from conventional commits. Live Foundry proof is intentionally left to a
real tenant run; the code and focused tests only claim the launch-mode
change inside Headroom.
