fix(config): strip control chars from saved env credentials

[ooiuuii]

Summary

Fixes #55335.

This strips ASCII control bytes (C0 plus DEL) from values passed through save_env_value() before Hermes writes .env and before it updates os.environ.

Hermes already stripped \n and \r, and already warns/strips non-ASCII credential artifacts. The missing gap was other ASCII controls such as NUL, TAB, ESC, and DEL:

• NUL can make os.environ[key] = value raise ValueError: embedded null character on Windows after the dirty value has already been written to .env.
• TAB/DEL survive silently in .env and process env, causing confusing provider auth/header failures later.

Validation

• Before the fix, the new regression test failed on Windows with ValueError: embedded null character.
• Direct repro after the fix stores and loads OPENAI_API_KEY=sk-livekeynext with no control bytes.
• python -m pytest tests/hermes_cli/test_config.py::TestSaveEnvValueSecure -q --basetemp .pytest-tmp-envsave → 9 passed
• python -m pytest tests/hermes_cli/test_non_ascii_credential.py -q --basetemp .pytest-tmp-nonascii → 12 passed
• ruff check hermes_cli/config.py tests/hermes_cli/test_config.py → passed
• git diff --check → passed

Local note: the full tests/hermes_cli/test_config.py file is not a clean Windows/GBK gate in this checkout; it has unrelated existing failures around the Windows default home expectation and locale-decoding UTF-8 config files. The touched save-env class passes.

Agent transcript

• Compared this against OpenClaw's recent secret-input control-character hardening and mapped it to Hermes' save_env_value() path.
• Searched open/closed Hermes issues and PRs for duplicate credential/control-byte reports. Adjacent work exists for FAL runtime validation and non-ASCII warnings, but not this save-time .env path.
• Reproduced the failure before changing code: NUL writes to .env then crashes on os.environ; TAB/DEL persist without crashing.
• Added a focused regression test and kept the implementation scoped to pre-existing env credential normalization.

[alt-glitch]

This was generated by AI during triage.
Competing with #40887 (earlier, still open) for the same save_env_value() save-time control-char gap. Scope differs: #40887 strips C0-except-TAB + C1 and adds http(s) validation for *_URL/_HOST/_ENDPOINT; this PR strips C0+DEL (including TAB) and explicitly handles the Windows os.environ NUL crash. Cross-linking so a maintainer can pick (or merge the superset). Also related: #25133 (getpass control chars on Windows).

[tonydwb]

LGTM. Strips ASCII control characters from saved credentials. Clean security fix with test.

[tonydwb]

Code Review Summary

Verdict: Approved

Strips ASCII control characters (below space, DEL) from saved environment credentials. This prevents invisible characters from being stored in .env files which could cause authentication failures.

✅ Looks Good

• Clean function that filters by ordinal value
• Good test coverage: verifies control chars are stripped, visible chars preserved
• Replaces the previous narrow newline-only stripping
• Works correctly with the existing non-ASCII check

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Reviewed by Hermes Agent

[teknium1]

Thanks for identifying the save-time control-byte gap. The central premise is still present on current main: hermes_cli/config.py:7554 only removes LF/CR before the helper writes the value and assigns it to os.environ at hermes_cli/config.py:7618.

Problems

• The TUI save flow calls save_env_value() at tui_gateway/server.py:12958 but then replaces the sanitized environment value with raw api_key at tui_gateway/server.py:12962. The same raw post-save overwrite exists in hermes_cli/secrets_cli.py:176-177 and hermes_cli/onepassword_secrets_cli.py:145-146; a NUL can still fail there after the clean .env write.
• The new helper applies to all save_env_value() inputs, while hermes_cli/mcp_catalog.py:438 documents that this writer stores non-secrets too. The unconditional TAB removal needs an explicit compatibility decision or narrower credential-only scope.

Suggested changes

• Eliminate or sanitize the post-save raw assignments and cover a TUI provider-key save regression.
• Specify and test the non-secret/TAB policy.

Automated hermes-sweeper review.

[teknium1]

save_env_value() itself updates os.environ, but tui_gateway/server.py:12958-12962, hermes_cli/secrets_cli.py:176-177, and hermes_cli/onepassword_secrets_cli.py:145-146 overwrite that entry with the original raw credential afterward. Please remove or sanitize those redundant assignments and add a path-level regression; otherwise a NUL still raises after the clean .env write.

[teknium1]

This helper is invoked for every save_env_value() call, including non-secret MCP catalog variables (hermes_cli/mcp_catalog.py:438). Please establish whether stripping TAB is intended for that broader API, or constrain the normalization to credential values.