Fresh Context Subagent Pattern Skill

Fresh Context Subagent Pattern

Problem: Context rot degrades quality as session accumulates history.

Solution: Fresh isolated context per subagent dispatch.

When to Use

Dispatching subagent for implementation task?
        ↓ YES
FRESH CONTEXT PROTOCOL ← APPLY

Use when:

Implementation tasks requiring isolated focus
Multi-file changes where context pollution risk exists
Quality-critical tasks requiring consistent reasoning
Tasks where parent session history could mislead

Don't use when:

Simple single-file edits (copy, rename, trivial changes)
Quick lookups (read-only, no implementation)
Context-independent tasks (no dependencies on session state)

Context Budget

| Task Type | Thinking Budget | Context Budget | Purpose | |-----------|-----------------|---------------|---------| | Implementation | ~20k tokens | ~200k tokens | Pure code generation | | Review | ~15k tokens | ~50k tokens | Focused quality check | | Research | ~10k tokens | ~100k tokens | Investigation tasks | | Debug | ~15k tokens | ~80k tokens | Root cause analysis |

Dispatch Protocol

Pre-Dispatch Checklist

Canonical reference: See rules/AGENTS.md — DELEGATION QUALITY CHECKLIST

This is the authoritative checklist. For quick reference:

□ Is runSubagent/Agent tool available? → TIER 1 (MANDATORY)
□ Task complexity assessed? → Simple/Standard/Complex
□ Specific file/directory boundaries assigned?
□ Acceptance criteria explicit in spawn prompt?
□ Subagent has MINIMAL context (not everything)?
□ Reviewer is DIFFERENT from executor?
□ File ownership is EXCLUSIVE (no conflicts)?
□ Wave grouping planned if multiple parallel tasks?
□ Token budget estimated for this phase?
□ Mailbox path confirmed and writable?
□ Confidence self-assessment completed?

Context Block Template

## SUBAGENT DISPATCH: {task_name}

### ISOLATED CONTEXT
{self-contained task description — what to do, NOT why}

### TARGET FILES
{file paths — exact locations to modify}

### ACCEPTANCE CRITERIA
1. {criterion_1 — verifiable outcome}
2. {criterion_2}
3. {criterion_n}

### CONTEXT ISOLATION
- NO parent session history
- NO previous attempts
- NO reasoning traces
- NO failed attempts
- Fresh context ONLY

### VERIFICATION STEPS
{how to verify task completion}

Post-Dispatch Verification

□ Task completed within budget?
□ Context not polluted by parent session?
□ Quality maintained at consistent level?
□ Isolation protocol followed?

Fresh-Context Implementation Pattern

In Skills/Commands

When dispatching subagents, ALWAYS follow this pattern:

## SUBAGENT DISPATCH

### Context Isolation
[TECH LEAD INSTRUCTION]
When spawning this subagent:
1. Create NEW context block (do not inherit parent)
2. Include ONLY: task, files, acceptance criteria
3. Exclude: session history, reasoning, attempts

### Task Requirements
{task description}

### Target Files
{file list}

### Acceptance Criteria
{checklist}

In Agent Definitions

---
name: executor
description: "Implementation agent with fresh context isolation"
context_rules:
  isolation: mandatory
  max_history: 0  # No parent history
  budget: 200k tokens
---

Context Budget Enforcement

Thinking Token Limits

| Tier | Model | Thinking Budget | Compaction Threshold | |------|-------|-----------------|---------------------| | A (Capable) | Opus-class | 20,000 | 60% | | B (Standard) | Sonnet-class | 10,000 | 50% | | C (Fast) | Haiku-class | 5,000 | 40% |

Per-Phase Budget Allocation

TOTAL THINKING BUDGET: {tier_budget}

Allocation:
├── Requirements capture: 10%
├── Implementation: 60%
├── Review: 20%
└── Buffer: 10%

Budget Tracking

## TOKEN BUDGET TRACKING

Task: {task_name}
Tier: {tier}
Budget: {tokens}
Used: {tokens}
Remaining: {tokens}
Status: WITHIN BUDGET / OVER BUDGET

If OVER BUDGET:
□ Compact context
□ Request budget increase
□ Defer low-priority requirements

Anti-Patterns to Avoid

❌ CONTEXT POLLUTION

BAD: "Based on our previous discussion about X..."
     "As we tried before in the session..."
     "Recall that the bug was caused by Y..."

GOOD: "Task requires fixing Z in file X"
      "Acceptance criteria: Z must work when..."
      "Test verification: run X and confirm Y"

❌ EXCESSIVE CONTEXT

BAD: "The entire codebase history, all failed attempts, 
      every file ever touched, complete session transcript..."

GOOD: "Fix bug in auth/token.ts — validate JWT expiration"
      "Test: POST /api/auth/login with expired token → 401"

❌ NO ACCEPTANCE CRITERIA

BAD: "Implement the feature" (vague)

GOOD: "Implement user registration:
       1. POST /api/users with email/password
       2. Return 201 with user object
       3. Validate email format, password min 8 chars
       4. Hash password with bcrypt
       5. Test: create user → verify password hashed"

Integration with Other Skills

With wave-execution

When dispatching parallel tasks:

Wave 1 tasks dispatch with FRESH CONTEXT
├── Task 1.1: fresh context → executor
├── Task 1.2: fresh context → executor
└── Task 1.3: fresh context → executor

With safety-guardrails

When debugging with freeze active:

Fresh context + restricted scope = safe implementation

Quality Metrics

| Metric | Target | Measurement | |--------|--------|------------| | Context isolation | 100% | No parent history in dispatch | | Budget adherence | <100% | Token usage per task | | Quality consistency | Stable | Output quality across session | | Context pollution | 0 incidents | Review findings |

Success Criteria

[ ] Context isolation protocol documented
[ ] Token budgets configured per tier
[ ] Dispatch template implemented
[ ] Anti-patterns avoided
[ ] Quality metrics tracked
[ ] Integration with wave-execution verified

DELEGATION QUALITY CHECKLIST

See rules/AGENTS.md § DELEGATION QUALITY CHECKLIST for the canonical 14-item checklist.

This skill follows that canonical checklist. Key highlights:

Tool discovery: TIER 1 mandatory
File ownership: exclusive per agent
Context: minimal, not everything
Reviewer: different from executor
Token budget: per-phase estimates

Agent Skills: Fresh Context Subagent Pattern

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Skill Files