fix: add OpenCode Zen and Go provider support (closes #362) (#392)

* Add OpenCode Zen and OpenCode Go provider support

The webui model dropdown had no knowledge of these providers.
When hermes_cli detected them as authenticated, they fell through
to the unknown-provider fallback showing wrong models.

Changes:
- Add opencode-zen and opencode-go to _PROVIDER_DISPLAY
- Add model lists for both to _PROVIDER_MODELS
- Add OPENCODE_ZEN_API_KEY and OPENCODE_GO_API_KEY to env-var fallback detection
- Fix custom:* provider IDs (e.g. custom:my-server) displaying raw ID instead of "Custom"

* Add tests for OpenCode provider registration and detection

---------

Co-authored-by: David Case <david.case@shruggr.cloud>

tests/test_opencode_providers.py

@@ -0,0 +1,70 @@
+"""
+Tests for OpenCode Zen and OpenCode Go provider support.
+Verifies provider registration in display/model catalogs and
+env-var fallback detection.
+"""
+import os
+import sys
+import types
+import api.config as config
+
+
+# ── Provider registration ─────────────────────────────────────────────
+
+def test_opencode_zen_in_provider_display():
+    assert "opencode-zen" in config._PROVIDER_DISPLAY
+    assert config._PROVIDER_DISPLAY["opencode-zen"] == "OpenCode Zen"
+
+
+def test_opencode_go_in_provider_display():
+    assert "opencode-go" in config._PROVIDER_DISPLAY
+    assert config._PROVIDER_DISPLAY["opencode-go"] == "OpenCode Go"
+
+
+def test_opencode_zen_in_provider_models():
+    assert "opencode-zen" in config._PROVIDER_MODELS
+    ids = [m["id"] for m in config._PROVIDER_MODELS["opencode-zen"]]
+    assert "claude-opus-4-6" in ids
+    assert "gpt-5.4-pro" in ids
+    assert "glm-5.1" in ids
+
+
+def test_opencode_go_in_provider_models():
+    assert "opencode-go" in config._PROVIDER_MODELS
+    ids = [m["id"] for m in config._PROVIDER_MODELS["opencode-go"]]
+    assert "glm-5.1" in ids
+    assert "glm-5" in ids
+    assert "mimo-v2-pro" in ids
+
+
+# ── Env-var fallback detection ────────────────────────────────────────
+
+def _models_with_env_key(monkeypatch, env_var, expected_provider_display):
+    """Helper: fake hermes_cli unavailable, set an env var, check detection."""
+    # Force the env-var fallback path by making hermes_cli import fail
+    fake_mod = types.ModuleType("hermes_cli.models")
+    fake_mod.list_available_providers = None  # will raise on call
+    monkeypatch.setitem(sys.modules, "hermes_cli.models", fake_mod)
+    monkeypatch.delattr(fake_mod, "list_available_providers")
+
+    old_cfg = dict(config.cfg)
+    config.cfg["model"] = {}
+    config.cfg.pop("custom_providers", None)
+    monkeypatch.setenv(env_var, "test-key")
+    try:
+        result = config.get_available_models()
+        providers = [g["provider"] for g in result["groups"]]
+        assert expected_provider_display in providers, (
+            f"Expected {expected_provider_display} in {providers}"
+        )
+    finally:
+        config.cfg.clear()
+        config.cfg.update(old_cfg)
+
+
+def test_opencode_zen_detected_via_env_key(monkeypatch):
+    _models_with_env_key(monkeypatch, "OPENCODE_ZEN_API_KEY", "OpenCode Zen")
+
+
+def test_opencode_go_detected_via_env_key(monkeypatch):
+    _models_with_env_key(monkeypatch, "OPENCODE_GO_API_KEY", "OpenCode Go")