chore: bump version to 0.4.2

- Fetch actual model defaults from Ollama's /api/show endpoint
- Parse YAML-like parameters field (e.g., "temperature 0.7")
- Cache model defaults to avoid repeated API calls
- Initialize sliders with model's actual values when enabling custom params
- Show asterisk indicator when parameter differs from model default
- Reset button now restores to model defaults, not hardcoded values

backend/cmd/server/main.go

@@ -18,7 +18,7 @@ import (
 )
 
 // Version is set at build time via -ldflags, or defaults to dev
-var Version = "0.4.1"
+var Version = "0.4.2"
 
 func getEnvOrDefault(key, defaultValue string) string {
 	if value := os.Getenv(key); value != "" {

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "vessel",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "private": true,
   "type": "module",
   "scripts": {

frontend/src/lib/components/settings/ModelParametersPanel.svelte

@@ -5,6 +5,7 @@
 	 */
 
 	import { settingsState } from '$lib/stores/settings.svelte';
+	import { modelsState, type ModelDefaults } from '$lib/stores/models.svelte';
 	import {
 		PARAMETER_RANGES,
 		PARAMETER_LABELS,
@@ -16,6 +17,26 @@
 	// Parameter keys for iteration
 	const parameterKeys: (keyof ModelParameters)[] = ['temperature', 'top_k', 'top_p', 'num_ctx'];
 
+	// Track model defaults for the selected model
+	let modelDefaults = $state<ModelDefaults>({});
+
+	// Fetch model defaults when panel opens or model changes
+	$effect(() => {
+		if (settingsState.isPanelOpen && modelsState.selectedId) {
+			modelsState.fetchModelDefaults(modelsState.selectedId).then((defaults) => {
+				modelDefaults = defaults;
+			});
+		}
+	});
+
+	/**
+	 * Get the default value for a parameter (from model or hardcoded fallback)
+	 */
+	function getDefaultValue(key: keyof ModelParameters): number {
+		const modelValue = modelDefaults[key];
+		return modelValue ?? DEFAULT_MODEL_PARAMETERS[key];
+	}
+
 	/**
 	 * Format a parameter value for display
 	 */
@@ -79,7 +100,7 @@
 				type="button"
 				role="switch"
 				aria-checked={settingsState.useCustomParameters}
-				onclick={() => settingsState.toggleCustomParameters()}
+				onclick={() => settingsState.toggleCustomParameters(modelDefaults)}
 				class="relative inline-flex h-5 w-9 flex-shrink-0 cursor-pointer rounded-full border-2 border-transparent transition-colors duration-200 ease-in-out focus:outline-none focus:ring-2 focus:ring-sky-500 focus:ring-offset-2 focus:ring-offset-theme-secondary {settingsState.useCustomParameters ? 'bg-sky-600' : 'bg-theme-tertiary'}"
 			>
 				<span
@@ -93,7 +114,7 @@
 			{#each parameterKeys as key}
 				{@const range = PARAMETER_RANGES[key]}
 				{@const value = getValue(key)}
-				{@const isDefault = value === DEFAULT_MODEL_PARAMETERS[key]}
+				{@const isDefault = value === getDefaultValue(key)}
 
 				<div>
 					<div class="mb-1 flex items-center justify-between">
@@ -132,7 +153,7 @@
 		<div class="mt-4 flex justify-end">
 			<button
 				type="button"
-				onclick={() => settingsState.resetToDefaults()}
+				onclick={() => settingsState.resetToDefaults(modelDefaults)}
 				class="rounded px-2 py-1 text-xs text-theme-muted hover:bg-theme-tertiary hover:text-theme-secondary"
 			>
 				Reset to defaults

frontend/src/lib/stores/models.svelte.ts

@@ -65,6 +65,14 @@ export interface ModelUpdateStatus {
 	localModifiedAt: string;
 }
 
+/** Model default parameters from Ollama */
+export interface ModelDefaults {
+	temperature?: number;
+	top_k?: number;
+	top_p?: number;
+	num_ctx?: number;
+}
+
 /** Models state class with reactive properties */
 export class ModelsState {
 	// Core state
@@ -81,6 +89,10 @@ export class ModelsState {
 	private capabilitiesCache = $state<Map<string, OllamaCapability[]>>(new Map());
 	private capabilitiesFetching = new Set<string>();
 
+	// Model defaults cache: modelName -> default parameters
+	private modelDefaultsCache = $state<Map<string, ModelDefaults>>(new Map());
+	private modelDefaultsFetching = new Set<string>();
+
 	// Derived: Currently selected model
 	selected = $derived.by(() => {
 		if (!this.selectedId) return null;
@@ -429,6 +441,99 @@ export class ModelsState {
 		}
 		return count;
 	}
+
+	// =========================================================================
+	// Model Defaults
+	// =========================================================================
+
+	/**
+	 * Parse model parameters from the Ollama show response
+	 * The parameters field contains lines like "temperature 0.7" or "num_ctx 4096"
+	 */
+	private parseModelParameters(parametersStr: string): ModelDefaults {
+		const defaults: ModelDefaults = {};
+
+		if (!parametersStr) return defaults;
+
+		const lines = parametersStr.split('\n');
+		for (const line of lines) {
+			const trimmed = line.trim();
+			if (!trimmed) continue;
+
+			// Parse "key value" format
+			const spaceIndex = trimmed.indexOf(' ');
+			if (spaceIndex === -1) continue;
+
+			const key = trimmed.substring(0, spaceIndex).toLowerCase();
+			const value = trimmed.substring(spaceIndex + 1).trim();
+
+			switch (key) {
+				case 'temperature':
+					defaults.temperature = parseFloat(value);
+					break;
+				case 'top_k':
+					defaults.top_k = parseInt(value, 10);
+					break;
+				case 'top_p':
+					defaults.top_p = parseFloat(value);
+					break;
+				case 'num_ctx':
+					defaults.num_ctx = parseInt(value, 10);
+					break;
+			}
+		}
+
+		return defaults;
+	}
+
+	/**
+	 * Fetch model defaults from Ollama /api/show
+	 */
+	async fetchModelDefaults(modelName: string): Promise<ModelDefaults> {
+		// Check cache first
+		const cached = this.modelDefaultsCache.get(modelName);
+		if (cached) return cached;
+
+		// Avoid duplicate fetches
+		if (this.modelDefaultsFetching.has(modelName)) {
+			await new Promise((r) => setTimeout(r, 100));
+			return this.modelDefaultsCache.get(modelName) ?? {};
+		}
+
+		this.modelDefaultsFetching.add(modelName);
+
+		try {
+			const response = await ollamaClient.showModel(modelName);
+			const defaults = this.parseModelParameters(response.parameters);
+
+			// Update cache reactively
+			const newCache = new Map(this.modelDefaultsCache);
+			newCache.set(modelName, defaults);
+			this.modelDefaultsCache = newCache;
+
+			return defaults;
+		} catch (err) {
+			console.warn(`Failed to fetch defaults for ${modelName}:`, err);
+			return {};
+		} finally {
+			this.modelDefaultsFetching.delete(modelName);
+		}
+	}
+
+	/**
+	 * Get cached model defaults (returns empty if not fetched)
+	 */
+	getModelDefaults(modelName: string): ModelDefaults {
+		return this.modelDefaultsCache.get(modelName) ?? {};
+	}
+
+	/**
+	 * Get defaults for selected model
+	 */
+	get selectedModelDefaults(): ModelDefaults {
+		if (!this.selectedId) return {};
+		return this.modelDefaultsCache.get(this.selectedId) ?? {};
+	}
 }
 
 /** Singleton models state instance */

frontend/src/lib/stores/settings.svelte.ts

@@ -10,6 +10,7 @@ import {
 	DEFAULT_CHAT_SETTINGS,
 	PARAMETER_RANGES
 } from '$lib/types/settings';
+import type { ModelDefaults } from './models.svelte';
 
 const STORAGE_KEY = 'vessel-settings';
 
@@ -79,12 +80,30 @@ export class SettingsState {
 
 	/**
 	 * Toggle whether to use custom parameters
+	 * When enabling, optionally initialize from model defaults
 	 */
-	toggleCustomParameters(): void {
+	toggleCustomParameters(modelDefaults?: ModelDefaults): void {
 		this.useCustomParameters = !this.useCustomParameters;
+
+		// When enabling custom parameters, initialize from model defaults if provided
+		if (this.useCustomParameters && modelDefaults) {
+			this.initializeFromModelDefaults(modelDefaults);
+		}
+
 		this.saveToStorage();
 	}
 
+	/**
+	 * Initialize parameters from model defaults
+	 * Falls back to hardcoded defaults for any missing values
+	 */
+	initializeFromModelDefaults(modelDefaults: ModelDefaults): void {
+		this.temperature = modelDefaults.temperature ?? DEFAULT_MODEL_PARAMETERS.temperature;
+		this.top_k = modelDefaults.top_k ?? DEFAULT_MODEL_PARAMETERS.top_k;
+		this.top_p = modelDefaults.top_p ?? DEFAULT_MODEL_PARAMETERS.top_p;
+		this.num_ctx = modelDefaults.num_ctx ?? DEFAULT_MODEL_PARAMETERS.num_ctx;
+	}
+
 	/**
 	 * Update a single parameter
 	 */
@@ -112,14 +131,13 @@ export class SettingsState {
 	}
 
 	/**
-	 * Reset all parameters to defaults
+	 * Reset all parameters to model defaults (or hardcoded defaults if not available)
 	 */
-	resetToDefaults(): void {
-		this.temperature = DEFAULT_MODEL_PARAMETERS.temperature;
-		this.top_k = DEFAULT_MODEL_PARAMETERS.top_k;
-		this.top_p = DEFAULT_MODEL_PARAMETERS.top_p;
-		this.num_ctx = DEFAULT_MODEL_PARAMETERS.num_ctx;
-		this.useCustomParameters = false;
+	resetToDefaults(modelDefaults?: ModelDefaults): void {
+		this.temperature = modelDefaults?.temperature ?? DEFAULT_MODEL_PARAMETERS.temperature;
+		this.top_k = modelDefaults?.top_k ?? DEFAULT_MODEL_PARAMETERS.top_k;
+		this.top_p = modelDefaults?.top_p ?? DEFAULT_MODEL_PARAMETERS.top_p;
+		this.num_ctx = modelDefaults?.num_ctx ?? DEFAULT_MODEL_PARAMETERS.num_ctx;
 		this.saveToStorage();
 	}