Send reasoning content back to the model across turns via the reasoning_content API field (#21036)

* webui: send reasoning_content back to model in context

Preserve assistant reasoning across turns by extracting it from
internal tags and sending it as a separate reasoning_content field
in the API payload. The server and Jinja templates handle native
formatting (e.g. <think> tags for Qwen, GLM, DeepSeek...).

Adds "Exclude reasoning from context" toggle in Settings > Developer
(off by default, so reasoning is preserved). Includes unit tests.

* webui: add syncable parameter for excludeReasoningFromContext

* chore: update webui build output

tools/server/webui/src/lib/constants/agentic.ts

@@ -50,6 +50,8 @@ export const AGENTIC_REGEX = {
 	PARTIAL_MARKER: /<<<[A-Za-z_]*$/,
 	// Matches reasoning content blocks (including tags)
 	REASONING_BLOCK: /<<<reasoning_content_start>>>[\s\S]*?<<<reasoning_content_end>>>/g,
+	// Captures the reasoning text between start/end tags
+	REASONING_EXTRACT: /<<<reasoning_content_start>>>([\s\S]*?)<<<reasoning_content_end>>>/,
 	// Matches an opening reasoning tag and any remaining content (unterminated)
 	REASONING_OPEN: /<<<reasoning_content_start>>>[\s\S]*$/,
 	// Matches a complete agentic tool call display block (start to end marker)

tools/server/webui/src/lib/constants/settings-config.ts

@@ -10,6 +10,7 @@ export const SETTING_CONFIG_DEFAULT: Record<string, string | number | boolean |
 	theme: ColorMode.SYSTEM,
 	showThoughtInProgress: false,
 	disableReasoningParsing: false,
+	excludeReasoningFromContext: false,
 	showRawOutputSwitch: false,
 	keepStatsVisible: false,
 	showMessageStats: true,
@@ -106,6 +107,8 @@ export const SETTING_CONFIG_INFO: Record<string, string> = {
 	showThoughtInProgress: 'Expand thought process by default when generating messages.',
 	disableReasoningParsing:
 		'Send reasoning_format=none to prevent server-side extraction of reasoning tokens into separate field',
+	excludeReasoningFromContext:
+		'Strip reasoning content from previous messages before sending to the model. When unchecked, reasoning is sent back via the reasoning_content field so the model can see its own chain-of-thought across turns.',
 	showRawOutputSwitch:
 		'Show toggle button to display messages as plain text instead of Markdown-formatted content',
 	keepStatsVisible: 'Keep processing statistics visible after generation finishes.',

tools/server/webui/src/lib/constants/settings-keys.ts

@@ -54,6 +54,7 @@ export const SETTINGS_KEYS = {
 	SHOW_TOOL_CALL_IN_PROGRESS: 'showToolCallInProgress',
 	// Developer
 	DISABLE_REASONING_PARSING: 'disableReasoningParsing',
+	EXCLUDE_REASONING_FROM_CONTEXT: 'excludeReasoningFromContext',
 	SHOW_RAW_OUTPUT_SWITCH: 'showRawOutputSwitch',
 	CUSTOM: 'custom'
 } as const;