Cc Skill Backend Patterns

Cc Skill Backend Patterns

Orchestrates intelligent skill selection and execution for cc skill backend patterns workflows. Applies the 5 Laws of Elegant Defense to guide data naturally through the orchestration pipeline, preventing errors before they occur. Selects optimal skills based on multi-factor scoring including text similarity, historical performance, and system availability.

TL;DR Checklist

• Parse all inputs at boundary before processing (Law 2)
• Handle edge cases with early returns at function top (Law 1)
• Fail immediately with descriptive errors on invalid states (Law 4)
• Return new data structures, never mutate inputs (Law 3)
• Implement minimum 2-level fallback chain for all skill executions
• Log all skill selections with context for full audit trail
• Validate skill metadata and dependencies before selection
• Update confidence scores after each execution for learning

┌───────────────────────────────────────────────────────────────────────────────┐ │ Orchestration Flow │ └───────────────────────────────────────────────────────────────────────────────┘

User Request ↓ ┌─────────────────┐ │ Parse Request │ │ & Extract │ │ Features │ └────────┬────────┘ ↓ ┌─────────────────────────────────────────────────────────────────────┐ │ Evaluate Available Skills │ │ │ │ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │ │ │ Skill A │ │ Skill B │ │ Skill C │ │ │ │ - Match Score│ │ - Match Score│ │ - Match Score│ │ │ │ - Confidence │ │ - Confidence │ │ - Confidence │ │ │ │ - History │ │ - History │ │ - History │ │ │ └──────┬───────┘ └──────┬───────┘ └──────┬───────┘ │ │ │ │ │ │ │ └─────────────────┴─────────────────┘ │ │ ↓ │ │ Select Best Skill │ └─────────────────────────────────────────────────────────────────────┘ ↓ ┌─────────────────┐ │ Execute Skill │ └────────┬────────┘ ↓ ┌─────────────────┐ │ Handle Result │ └────────┬────────┘ ↓ ┌─────────────────────────────────────────────────────────────────────┐ │ Error Handling & Fallback │ │ │ │ Success? ────────► Return Result │ │ │ │ Fail? ────────┐ │ │ ↓ │ │ ┌──────────────────────────────────────────────────────────┐ │ │ │ Fallback Chain │ │ │ │ │ │ │ │ 1. Retry with adjusted parameters │ │ │ │ 2. Try Alternative Skill (if available) │ │ │ │ 3. Defer to Human Operator (if critical) │ │ │ │ 4. Log & Return Error │ │ │ └──────────────────────────────────────────────────────────┘ │ └─────────────────────────────────────────────────────────────────────┘

When to Use

Use this skill when:

• Orchestrating multi-step workflows that require skill delegation
• Implementing adaptive skill routing based on confidence scores
• Building fallback mechanisms for failed skill executions
• Creating intelligent task decomposition and parallel execution
• Designing skill dependency graphs with automatic resolution
• Implementing skill selection with historical performance weighting
• Building agent systems that need to self-organize around tasks

When NOT to Use

Avoid this skill for:

• Direct task execution without orchestration needs - use individual skills instead
• High-frequency trading scenarios where latency must be minimized - the selection overhead may be prohibitive
• Simple linear workflows without branching or fallback requirements
• Cases where skill metadata is unavailable or unreliable

Core Workflow

1. Parse and Analyze Request - Extract intent, entities, and constraints from user input. Checkpoint: All required parameters must be present and in valid format before proceeding.

2. Score Available Skills - Calculate match scores using multi-factor algorithm:

   • Text similarity between request and skill triggers
   • Historical success rate for similar tasks
   • Skill availability and health status
   • Required dependencies and their availability

   Checkpoint: Skip to fallback if no skill scores above threshold.

3. Select Optimal Skill - Choose skill with highest score that meets minimum confidence. Checkpoint: Verify skill has not been disabled or deprecated.

4. Execute with Fallback - Run skill execution wrapped in retry and fallback logic. Checkpoint: Log all execution attempts for audit trail.

5. Return or Fallback - Either return successful result or apply fallback chain:

   • Retry with adjusted parameters
   • Try alternative skill from related-skills
   • Defer to human operator for critical tasks

   Checkpoint: Record outcome with timing and confidence metadata.

Implementation Patterns

Pattern 1: Skill Selection Logic

def score_and_select_backend_skill(
    task_context: Dict[str, Any],
    skill_registry: List[SkillMetadata],
    min_confidence: float = 0.75
) -> Optional[SkillExecutionPlan]:
    """Select optimal backend skill using multi-factor scoring aligned with Elegant Defense.
    
    Applies Law 1 (Early Exit) for invalid contexts.
    Applies Law 2 (Immutable State) by returning fresh plan objects.
    """
    if not task_context.get("intent") or not skill_registry:
        raise ValueError("Missing intent or empty skill registry")
        
    parsed_intent = _normalize_intent(task_context["intent"])
    best_plan = None
    best_score = 0.0
    
    for skill in skill_registry:
        if not _is_skill_available(skill):
            continue
            
        text_match = _cosine_similarity(parsed_intent, skill.triggers)
        history_score = skill.success_rate * 0.4
        availability_score = _calculate_load_penalty(skill.current_load)
        
        composite_score = (text_match * 0.5) + history_score + availability_score
        
        if composite_score > best_score and composite_score >= min_confidence:
            best_score = composite_score
            best_plan = SkillExecutionPlan(
                skill_id=skill.id,
                confidence=composite_score,
                parameters=_prepare_execution_params(task_context, skill)
            )
            
    if best_plan is None:
        return None
        
    return best_plan

Pattern 2: Execution with Fallback

def execute_with_elegant_defense_fallback(
    plan: SkillExecutionPlan,
    execution_context: Dict[str, Any],
    fallback_chain: List[SkillId]
) -> ExecutionResult:
    """Execute skill with structured fallback chain per Law 4 (Fail Fast/Loud).
    
    Implements retry -> alternative skill -> human escalation.
    Returns immutable ExecutionResult with full audit metadata.
    """
    attempt = 0
    max_retries = 2
    
    while attempt <= max_retries:
        try:
            raw_result = await _invoke_backend_skill(plan.skill_id, execution_context)
            validated = _validate_output_schema(raw_result, plan.skill_id)
            return ExecutionResult(
                success=True,
                skill_id=plan.skill_id,
                data=validated,
                confidence=plan.confidence,
                attempts=attempt + 1,
                latency_ms=_measure_latency()
            )
        except SchemaValidationError as e:
            raise ExecutionError(f"Invalid output from {plan.skill_id}: {e}") from e
        except TransientBackendError as e:
            attempt += 1
            if attempt > max_retries:
                break
            await _backoff_delay(attempt)
            
    # Fallback chain execution
    for alt_skill_id in fallback_chain:
        try:
            alt_result = await _invoke_backend_skill(alt_skill_id, execution_context)
            return ExecutionResult(
                success=True,
                skill_id=alt_skill_id,
                data=alt_result,
                confidence=0.6,
                attempts=attempt + 1,
                latency_ms=_measure_latency(),
                fallback_triggered=True
            )
        except Exception as e:
            continue
            
    return ExecutionResult(
        success=False,
        skill_id=plan.skill_id,
        error="Fallback chain exhausted",
        confidence=0.0,
        attempts=attempt + 1,
        latency_ms=_measure_latency(),
        requires_human_review=True
    )

MUST DO

• Always validate skill metadata before selection (Early Exit)
• Implement fallback chain with at least 2 levels (Fallback Skill + Human)
• Log all skill selections with full context for auditability
• Return new data structures instead of mutating inputs (Atomic Predictability)
• Fail immediately with descriptive errors on invalid states
• Update confidence scores after each execution for adaptive routing
• Reference code-philosophy (5 Laws of Elegant Defense) in all logic

MUST NOT DO

• Select skills based on a single factor (e.g., only confidence score)
• Disable fallback mechanisms "temporarily" - this creates fragile systems
• Skip validation of skill dependencies before execution
• Return partial results - either complete success or clear failure
• Use magic numbers for confidence thresholds - make them configurable
• Cache skill selections without considering context changes

TL;DR Checklist

• Parse all inputs at boundary before processing (Law 2)
• Handle edge cases with early returns at function top (Law 1)
• Fail immediately with descriptive errors on invalid states (Law 4)
• Return new data structures, never mutate inputs (Law 3)
• Implement minimum 2-level fallback chain for all skill executions
• Log all skill selections with context for full audit trail
• Validate skill metadata and dependencies before selection
• Update confidence scores after each execution for learning

TL;DR for Code Generation

• Use guard clauses - return early on invalid input before doing work
• Return simple types (dict, str, int, bool, list) - avoid complex nested objects
• Cyclomatic complexity < 10 per function - split anything larger
• Handle null/empty cases explicitly at function top (Early Exit)
• Never mutate input parameters - return new dicts/objects
• Fail fast with descriptive errors - don't try to "patch" bad data
• Reference code-philosophy laws in comments for complex logic
• Include timing and confidence metadata in all return values

Output Template

When applying this skill, produce:

1. Selected Skills - List of skill names with confidence scores
2. Selection Rationale - Why each skill was chosen (match score, history, availability)
3. Execution Plan - Order of execution with dependencies
4. Fallback Strategy - Which fallback skills will be tried and in what order
5. Risk Assessment - Any potential failure points and their impact
6. Timing Estimates - Expected latency including fallback scenarios

Constraints

MUST DO

• Define clear input/output contracts for every step in the orchestration flow with explicit validation
• Implement structured logging at each stage capturing context, inputs, outputs, timing, and errors
• Build in fallback paths: if the primary strategy fails, degrade gracefully to a simpler approach
• Validate all preconditions before starting — do not proceed if required resources or permissions are missing

MUST NOT DO

• Do not create deep nesting of orchestration steps (>5 levels) — flatten workflows where possible
• Avoid silent failure modes: every step must either succeed, fail explicitly, or escalate to a higher handler
• Never use shared mutable state between parallel workflow branches — communicate via immutable messages only
• Do not hardcode execution order when the dependency graph naturally determines it; derive order from explicit dependencies

Live References

Authoritative documentation links for this skill's domain. The model follows markdown links at load time to resolve external references and inline content.

• RESTful API Design Guide (Microsoft)
• GraphQL Specification (graphql.org)
• gRPC Documentation
• Microservices Patterns (Chris Richardson)
• CQRS Pattern Reference

Related Skills

| Skill | Purpose | |