feat(ai): implemented fallback handling and option for qwen reasoning effort

- Added `qwenTemplateReasoningEffort` model compatibility option to disable Qwen chat template kwargs for strict local servers.
- Implemented fallback handling to strip rejected `chat_template_kwargs.reasoning_effort` and hoist values to top-level fields.
- Added comprehensive test coverage for Qwen reasoning effort fallback and keyword rejections.

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- Added `qwenTemplateReasoningEffort` to the `models.yml` `compat` schema, so the auto-enabled Qwen 3.8+ template effort dialect (`chat_template_kwargs.reasoning_effort`) can be switched off per provider/model for strict local servers that reject unknown `chat_template_kwargs`.
+
 ### Changed
 
 - `/settings` rows can now carry a risk note: a warning glyph on the row plus a warning-colored line above the description. `External Thinking` (`externalThinking`, `--external-thinking`) is the first user — providers have flagged the request shape it produces as abuse, up to account-level enforcement, so both the settings entry and `--help` now say so.

packages/coding-agent/src/config/models-config-schema-bundle.ts

@@ -42,6 +42,7 @@ export const getModelsConfigSchemaBundle = once(() => {
 		"disableReasoningOnForcedToolChoice?": "boolean",
 		"disableReasoningOnToolChoice?": "boolean",
 		"thinkingFormat?": '"openai" | "openrouter" | "zai" | "qwen" | "qwen-chat-template"',
+		"qwenTemplateReasoningEffort?": "boolean",
 		"openRouterRouting?": OpenRouterRoutingSchema,
 		"vercelGatewayRouting?": VercelGatewayRoutingSchema,
 		"extraBody?": { "[string]": "unknown" },