fix(integrations): declare OpencodeIntegration multi_install_safe (#4620)

[philo-x]

Description

Closes #4620.

Declare OpencodeIntegration.multi_install_safe = True so OpenCode can be installed alongside Codex and other declared-safe integrations without --force, and the missing declaration no longer causes unsafe-multi-install status findings. Add a focused regression assertion and list .opencode/commands in the multi-install-safe reference table.

The existing registry contracts now include OpenCode in static-path checks, all 351 integration pairs for root and command-directory isolation, and all 27 rotated installation orders for manifest isolation.

Documentation note for maintainers: dsh and vibe also declare multi-install safety but are absent from this table. Those pre-existing omissions are left for a separate documentation change.

Testing

• .venv/bin/python -m pytest tests/integrations/test_registry.py tests/integrations/test_integration_opencode.py -q — 852 passed on the latest upstream main baseline.
• Verified the new regression test fails when OpenCode's declaration is set back to False in memory.
• .venv/bin/specify --help — passed.
• git diff upstream/main --check — passed.

The registry contracts exercise sample-project initialization and installation without --force. No slash-command content or execution behavior changed. The full repository test suite was not run.

AI Disclosure

Implemented and tested on behalf of @philo-x by Codex (GPT-6), operating autonomously from the user's supplied diagnosis and three-file repair plan. Codex authored the changes, ran validation, and submitted this PR. The commit includes an Assisted-by: trailer.

[Copilot]

🟢 Approval recommended

The focused change is consistent with OpenCode’s isolated paths and is covered by regression and registry contract tests.

Pull request overview

Declares OpenCode safe for concurrent installation with other isolated integrations.

Changes:

• Enables multi_install_safe for OpenCode.
• Adds a regression assertion.
• Documents OpenCode’s command directory.

File summaries

File	Description
src/specify_cli/integrations/opencode/__init__.py	Enables safe multi-installation.
tests/integrations/test_integration_opencode.py	Guards the declaration.
docs/reference/integrations.md	Adds OpenCode to the safety table.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Balanced

---

💡 Configure MCP servers for context-aware, tailored reviews. Learn more in the docs.