feat(ai): Enhance Perplexity research calls & fix docs examples

Improves the quality and relevance of research-backed AI operations:
- Tweaks Perplexity AI calls to use max input tokens (8700), temperature 0.1, high context size, and day-fresh search recency.
- Adds a system prompt to guide Perplexity research output.

Docs:
- Updates CLI examples in taskmaster.mdc to use ANSI-C quoting ($'...') for multi-line prompts, ensuring they work correctly in bash/zsh.

scripts/modules/ai-services.js

@@ -709,12 +709,24 @@ Include concrete code examples and technical considerations where relevant.`;
 		const researchResponse = await perplexityClient.chat.completions.create({
 			model: PERPLEXITY_MODEL,
 			messages: [
+				{
+					role: 'system',
+					content: `You are a helpful assistant that provides research on current best practices and implementation approaches for software development.
+					You are given a task and a description of the task.
+					You need to provide a list of best practices, libraries, design patterns, and implementation approaches that are relevant to the task.
+					You should provide concrete code examples and technical considerations where relevant.`
+				},
 				{
 					role: 'user',
 					content: researchQuery
 				}
 			],
-			temperature: 0.1 // Lower temperature for more factual responses
+			temperature: 0.1, // Lower temperature for more factual responses
+			max_tokens: 8700, // Respect maximum input tokens for Perplexity (8719 max)
+			web_search_options: {
+				search_context_size: 'high'
+			},
+			search_recency_filter: 'day' // Filter for results that are as recent as today to capture new releases
 		});
 
 		const researchResult = researchResponse.choices[0].message.content;
@@ -814,7 +826,7 @@ Note on dependencies: Subtasks can depend on other subtasks with lower IDs. Use
 				anthropic,
 				{
 					model: session?.env?.ANTHROPIC_MODEL || CONFIG.model,
-					max_tokens: session?.env?.MAX_TOKENS || CONFIG.maxTokens,
+					max_tokens: 8700,
 					temperature: session?.env?.TEMPERATURE || CONFIG.temperature,
 					system: systemPrompt,
 					messages: [{ role: 'user', content: userPrompt }]
@@ -1328,7 +1340,12 @@ Include concrete code examples and technical considerations where relevant.`;
 					content: researchQuery
 				}
 			],
-			temperature: 0.1 // Lower temperature for more factual responses
+			temperature: 0.1, // Lower temperature for more factual responses
+			max_tokens: 8700, // Respect maximum input tokens for Perplexity (8719 max)
+			web_search_options: {
+				search_context_size: 'high'
+			},
+			search_recency_filter: 'day' // Filter for results that are as recent as today to capture new releases
 		});
 
 		const researchResult = researchResponse.choices[0].message.content;

scripts/modules/task-manager.js

@@ -427,11 +427,7 @@ Return only the updated tasks as a valid JSON array.`
 									session?.env?.TEMPERATURE ||
 									CONFIG.temperature
 							),
-							max_tokens: parseInt(
-								process.env.MAX_TOKENS ||
-									session?.env?.MAX_TOKENS ||
-									CONFIG.maxTokens
-							)
+							max_tokens: 8700
 						});
 
 						const responseText = result.choices[0].message.content;
@@ -972,11 +968,7 @@ Return only the updated task as a valid JSON object.`
 									session?.env?.TEMPERATURE ||
 									CONFIG.temperature
 							),
-							max_tokens: parseInt(
-								process.env.MAX_TOKENS ||
-									session?.env?.MAX_TOKENS ||
-									CONFIG.maxTokens
-							)
+							max_tokens: 8700
 						});
 
 						const responseText = result.choices[0].message.content;
@@ -3738,7 +3730,11 @@ DO NOT include any text before or after the JSON array. No explanations, no mark
 							}
 						],
 						temperature: session?.env?.TEMPERATURE || CONFIG.temperature,
-						max_tokens: session?.env?.MAX_TOKENS || CONFIG.maxTokens
+						max_tokens: 8700,
+						web_search_options: {
+							search_context_size: 'high'
+						},
+						search_recency_filter: 'day'
 					});
 
 					// Extract the response text