fix(config): stop _normalize_custom_provider_entry mutating the caller's dict

[hashbender]

What does this PR do?

Stops _normalize_custom_provider_entry (hermes_cli/config.py) from mutating the dict it is passed.

The normalizer builds and returns a fresh normalized dict, but on the way it writes alias keys into its input:

if "api_key_env" in entry and "key_env" not in entry:
    entry["key_env"] = entry["api_key_env"]
...
for camel, snake in _CAMEL_ALIASES.items():
    if camel in entry and snake not in entry:
        entry[snake] = entry[camel]

Two of its three callers — get_compatible_custom_providers and providers_dict_to_custom_providers — pass live sub-dicts from load_config_readonly()'s shared cache, which has an explicit no-mutation contract. (The third caller, _custom_provider_entry_to_provider_config, already defends itself with dict(entry) — evidence the hazard was known but two paths were missed.)

Consequences for a config written with the documented camelCase / api_key_env aliases:

• the cached config gains injected duplicate keys (baseUrl and base_url, apiKeyEnv and key_env), so every later load_config() deepcopy inherits them, and any save_config(load_config()) flow (setup wizard, dashboard config writes, model persist) writes the duplicates back to config.yaml;
• the recent custom-provider TLS work made this hot-path: _resolve_aux_verify runs it on every auxiliary-client build (compression, vision, title-gen), i.e. an unlocked dict mutation on a shared object from worker threads;
• open PR perf: use load_config_readonly() at read-only call sites in agent/ NousResearch/hermes-agent#56085 (load_config_readonly() at 31 read-only call sites in agent/) widens the blast radius further — several of those sites reach this normalizer.

Repro on current main:

cfg = {"custom_providers": [{"name": "x", "baseUrl": "https://a/v1", "apiKeyEnv": "K"}]}
get_compatible_custom_providers(cfg)
cfg["custom_providers"][0].keys()
# dict_keys(['name', 'baseUrl', 'apiKeyEnv', 'base_url', 'key_env'])  ← polluted

The fix is a shallow entry = dict(entry) at the top of the normalizer. The return value is a separately-built dict, so nothing else changes.

Related Issue

None filed. Alias handling introduced for NousResearch#9332; the readonly-cache interaction is what makes it bite.

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Changes Made

• hermes_cli/config.py — shallow-copy the entry before alias normalization (+ comment explaining why).
• tests/hermes_cli/test_provider_config_validation.py — 3 regression tests: camelCase entry unchanged, api_key_env entry unchanged, and get_compatible_custom_providers leaves the whole config deep-equal to a snapshot.

How to Test

scripts/run_tests.sh tests/hermes_cli/test_provider_config_validation.py

All 3 new tests fail on current main and pass with the fix; the file's other 21 tests pass on both. Also green: tests/hermes_cli/test_config.py, test_custom_provider_tls.py, test_runtime_provider_resolution.py, tests/agent/test_auxiliary_named_custom_providers.py (317 tests, macOS 15). scripts/check-windows-footguns.py clean.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (N/A — internal contract fix)
• My changes generate no new warnings
• I have added tests that prove my fix is effective
• New and existing unit tests pass locally with my changes

---

Mirror-of: NousResearch#57096
NousResearch#57096