refactor(prompts): enrich explore/librarian delegation examples with structured context handoff

Expand prompt structure comment to 4-field format (CONTEXT/GOAL/DOWNSTREAM/REQUEST).
Update all explore/librarian task() examples across Sisyphus, Hephaestus,
Prometheus interview-mode, and both ultrawork variants with richer context
including downstream usage, scope limits, and return format expectations.

src/agents/hephaestus.ts

@@ -278,13 +278,19 @@ ${librarianSection}
 
 \`\`\`typescript
 // CORRECT: Always background, always parallel
-// Prompt structure: [CONTEXT: what I'm doing] + [GOAL: what I'm trying to achieve] + [QUESTION: what I need to know] + [REQUEST: what to find]
+// Prompt structure (each field should be substantive, not a single sentence):
+//   [CONTEXT]: What task I'm working on, which files/modules are involved, and what approach I'm taking
+//   [GOAL]: The specific outcome I need — what decision or action the results will unblock
+//   [DOWNSTREAM]: How I will use the results — what I'll build/decide based on what's found
+//   [REQUEST]: Concrete search instructions — what to find, what format to return, and what to SKIP
+
 // Contextual Grep (internal)
-task(subagent_type="explore", run_in_background=true, load_skills=[], prompt="I'm implementing user authentication for our API. I need to understand how auth is currently structured in this codebase. Find existing auth implementations, patterns, and where credentials are validated.")
-task(subagent_type="explore", run_in_background=true, load_skills=[], prompt="I'm adding error handling to the auth flow. I want to follow existing project conventions for consistency. Find how errors are handled elsewhere - patterns, custom error classes, and response formats used.")
+task(subagent_type="explore", run_in_background=true, load_skills=[], description="Find auth implementations", prompt="I'm implementing JWT auth for the REST API in src/api/routes/. I need to match existing auth conventions so my code fits seamlessly. I'll use this to decide middleware structure and token flow. Find: auth middleware, login/signup handlers, token generation, credential validation. Focus on src/ — skip tests. Return file paths with pattern descriptions.")
+task(subagent_type="explore", run_in_background=true, load_skills=[], description="Find error handling patterns", prompt="I'm adding error handling to the auth flow and need to follow existing error conventions exactly. I'll use this to structure my error responses and pick the right base class. Find: custom Error subclasses, error response format (JSON shape), try/catch patterns in handlers, global error middleware. Skip test files. Return the error class hierarchy and response format.")
+
 // Reference Grep (external)
-task(subagent_type="librarian", run_in_background=true, load_skills=[], prompt="I'm implementing JWT-based auth and need to ensure security best practices. Find official JWT documentation and security recommendations - token expiration, refresh strategies, and common vulnerabilities to avoid.")
-task(subagent_type="librarian", run_in_background=true, load_skills=[], prompt="I'm building Express middleware for auth and want production-quality patterns. Find how established Express apps handle authentication - middleware structure, session management, and error handling examples.")
+task(subagent_type="librarian", run_in_background=true, load_skills=[], description="Find JWT security docs", prompt="I'm implementing JWT auth and need current security best practices to choose token storage (httpOnly cookies vs localStorage) and set expiration policy. Find: OWASP auth guidelines, recommended token lifetimes, refresh token rotation strategies, common JWT vulnerabilities. Skip 'what is JWT' tutorials — production security guidance only.")
+task(subagent_type="librarian", run_in_background=true, load_skills=[], description="Find Express auth patterns", prompt="I'm building Express auth middleware and need production-quality patterns to structure my middleware chain. Find how established Express apps (1000+ stars) handle: middleware ordering, token refresh, role-based access control, auth error propagation. Skip basic tutorials — I need battle-tested patterns with proper error handling.")
 // Continue immediately - collect results when needed
 
 // WRONG: Sequential or blocking - NEVER DO THIS