fix(computer-server): default to localhost binding

[0xjohnnydev]

Recreates #1571 from current main.

Security:

• Defaults computer-server host binding to 127.0.0.1.
• Preserves explicit --host 0.0.0.0 opt-in.

Validation:

• parse_args([]).host == 127.0.0.1
• Server().host == 127.0.0.1
• parse_args([--host, 0.0.0.0]).host == 0.0.0.0
• Live server without --host listened on TCP 127.0.0.1 only.

Summary by CodeRabbit

• Bug Fixes

  • Server now binds to localhost by default instead of all network interfaces, improving default security posture.
  • External connections now require explicitly passing the --host configuration flag.

• Documentation

  • Updated documentation with instructions for configuring external access.

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Project	Deployment	Actions	Updated (UTC)
docs	Ready	Preview, Comment	Jun 4, 2026 6:39pm

[github-actions]

📦 Publishable packages changed

• pypi/computer-server

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📝 Walkthrough

Walkthrough

The pull request changes the default network binding for computer_server from 0.0.0.0 (all interfaces) to 127.0.0.1 (localhost only). The Server class constructor, CLI argument parser, README, and changelog are all updated to reflect this constraint and document how to enable external access.

Changes

Localhost-only default binding

Layer / File(s)	Summary
Server and CLI default binding libs/python/computer-server/computer_server/server.py, libs/python/computer-server/computer_server/cli.py	Server.__init__ and the CLI --host argument both default to 127.0.0.1 instead of 0.0.0.0. Parameter docstrings are updated to document the localhost default and explain passing 0.0.0.0 explicitly for external access.
README and changelog documentation libs/python/computer-server/README.md, changelog/2026-05-18.md	README adds an example showing --host 0.0.0.0 for external access and clarifies the localhost-only default. Changelog documents the highlights of the change.

🎯 1 (Trivial) | ⏱️ ~3 minutes

🐇 A server once bound to all,
Now localhost heeds the call,
Safer by default, snug and tight—
external access needs explicit might. 🔐

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix(computer-server): default to localhost binding' accurately summarizes the main change: switching the default host binding from 0.0.0.0 to 127.0.0.1.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch security/computer-server-localhost-default

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Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

📦 Publishable packages changed

• pypi/computer-server

Add release:<service> labels to auto-release on merge (+ optional bump:minor or bump:major, default is patch).
Or add no-release to skip.

[github-actions]

📦 Publishable packages changed

• pypi/computer-server

Add release:<service> labels to auto-release on merge (+ optional bump:minor or bump:major, default is patch).
Or add no-release to skip.

[github-actions]

📦 Publishable packages changed

• pypi/computer-server

Add release:<service> labels to auto-release on merge (+ optional bump:minor or bump:major, default is patch).
Or add no-release to skip.

[f-trycua]

Nice — this covers the two real bind sites (cli.py --host default + Server.host default), which is the path python -m computer_server actually takes, so it closes the #1892 network exposure for the documented entrypoint.

One loose end: there's a third hardcoded bind in main.py:1433:

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

It's only reached via a direct run (python -m computer_server.main / running main.py), not the __main__.py → cli.main() path this PR fixes, so it's lower-risk — but for completeness it should be 127.0.0.1 too (or read the CLI default) so no entrypoint binds wide. Happy to push that one-liner if useful.