fix: repair OpenCode model routing and selection (#4508)

OpenCode Zen and Go are mixed-API-surface providers — different models
behind them use different API surfaces (GPT on Zen uses codex_responses,
Claude on Zen uses anthropic_messages, MiniMax on Go uses
anthropic_messages, GLM/Kimi on Go use chat_completions).

Changes:
- Add normalize_opencode_model_id() and opencode_model_api_mode() to
  models.py for model ID normalization and API surface routing
- Add _provider_supports_explicit_api_mode() to runtime_provider.py
  to prevent stale api_mode from leaking across provider switches
- Wire opencode routing into all three api_mode resolution paths:
  pool entry, api_key provider, and explicit runtime
- Add api_mode field to ModelSwitchResult for propagation through the
  switch pipeline
- Consolidate _PROVIDER_MODELS from main.py into models.py (single
  source of truth, eliminates duplicate dict)
- Add opencode normalization to setup wizard and model picker flows
- Add opencode block to _normalize_model_for_provider in CLI
- Add opencode-zen/go fallback model lists to setup.py

Tests: 160 targeted tests pass (26 new tests covering normalization,
api_mode routing per provider/model, persistence, and setup wizard
normalization).

Based on PR #3017 by SaM13997.

Co-authored-by: SaM13997 <139419381+SaM13997@users.noreply.github.com>

hermes_cli/runtime_provider.py

@@ -82,9 +82,27 @@ def _get_model_config() -> Dict[str, Any]:
     return {}
 
 
+def _provider_supports_explicit_api_mode(provider: Optional[str], configured_provider: Optional[str] = None) -> bool:
+    """Check whether a persisted api_mode should be honored for a given provider.
+
+    Prevents stale api_mode from a previous provider leaking into a
+    different one after a model/provider switch.  Only applies the
+    persisted mode when the config's provider matches the runtime
+    provider (or when no configured provider is recorded).
+    """
+    normalized_provider = (provider or "").strip().lower()
+    normalized_configured = (configured_provider or "").strip().lower()
+    if not normalized_configured:
+        return True
+    if normalized_provider == "custom":
+        return normalized_configured == "custom" or normalized_configured.startswith("custom:")
+    return normalized_configured == normalized_provider
+
+
 def _copilot_runtime_api_mode(model_cfg: Dict[str, Any], api_key: str) -> str:
+    configured_provider = str(model_cfg.get("provider") or "").strip().lower()
     configured_mode = _parse_api_mode(model_cfg.get("api_mode"))
-    if configured_mode:
+    if configured_mode and _provider_supports_explicit_api_mode("copilot", configured_provider):
         return configured_mode
 
     model_name = str(model_cfg.get("default") or "").strip()
@@ -140,9 +158,13 @@ def _resolve_runtime_from_pool_entry(
     elif provider == "copilot":
         api_mode = _copilot_runtime_api_mode(model_cfg, getattr(entry, "runtime_api_key", ""))
     else:
+        configured_provider = str(model_cfg.get("provider") or "").strip().lower()
         configured_mode = _parse_api_mode(model_cfg.get("api_mode"))
-        if configured_mode:
+        if configured_mode and _provider_supports_explicit_api_mode(provider, configured_provider):
             api_mode = configured_mode
+        elif provider in ("opencode-zen", "opencode-go"):
+            from hermes_cli.models import opencode_model_api_mode
+            api_mode = opencode_model_api_mode(provider, model_cfg.get("default", ""))
         elif base_url.rstrip("/").endswith("/anthropic"):
             api_mode = "anthropic_messages"
 
@@ -666,10 +688,14 @@ def resolve_runtime_provider(
         if provider == "copilot":
             api_mode = _copilot_runtime_api_mode(model_cfg, creds.get("api_key", ""))
         else:
-            # Check explicit api_mode from model config first
+            configured_provider = str(model_cfg.get("provider") or "").strip().lower()
+            # Only honor persisted api_mode when it belongs to the same provider family.
             configured_mode = _parse_api_mode(model_cfg.get("api_mode"))
-            if configured_mode:
+            if configured_mode and _provider_supports_explicit_api_mode(provider, configured_provider):
                 api_mode = configured_mode
+            elif provider in ("opencode-zen", "opencode-go"):
+                from hermes_cli.models import opencode_model_api_mode
+                api_mode = opencode_model_api_mode(provider, model_cfg.get("default", ""))
             # Auto-detect Anthropic-compatible endpoints by URL convention
             # (e.g. https://api.minimax.io/anthropic, https://dashscope.../anthropic)
             elif base_url.rstrip("/").endswith("/anthropic"):