| name | context-engineer |
| description | Determines WHAT context an agent needs and packages it optimally. Actions: analyze (identify needed context), load (assemble from sources), prune (trim to token budget), inject (write to .claude/context-payload.md). Use when: (1) before spawning teammates, (2) context window is limited, (3) multi-source context assembly. Triggers: /context-engineer, 'prepare context', 'package context', 'context for agent'. |
| argument-hint | <task description> |
| user-invocable | true |
Context Engineer v3.0
Determine what context an agent needs and package it within token budget.
Actions
/context-engineer analyze <task>
Identify what context sources are relevant:
- Parse task description for domain keywords
- Check for DESIGN.md (frontend tasks)
- Check for .spec.md files (spec-driven tasks)
- Check memory sources (vault, handoffs, ledgers)
- Check codebase files (Glob/Grep for related code)
- Output: ranked list of context sources with estimated tokens
/context-engineer load <task>
Assemble context from identified sources:
- Run
analyze if not already done
- Read each source, extract relevant sections
- Prioritize by relevance score
- Output: assembled context block
/context-engineer prune <budget>
Trim assembled context to fit token budget:
- Default budget: 8000 tokens
- Remove low-relevance sections first
- Summarize long sections instead of including full text
- Preserve: interfaces, invariants, design tokens (high signal)
- Output: pruned context within budget
/context-engineer inject
Write packaged context to .claude/context-payload.md:
- Write pruned context to file
- The
ralph-subagent-start.sh hook reads this file and injects into teammate prompt
- File is gitignored (per Item 0a)
Context Sources (Priority Order)
| Source | When Relevant | Token Cost |
|---|
| .spec.md | Task has a spec | ~500-2000 |
| DESIGN.md | Frontend task | ~1000-3000 |
| Related code files | Always | ~500-5000 |
| Memory (vault) | Prior work exists | ~200-500 |
| Handoffs | Cross-session | ~300-800 |
| Vault (future) | Curated knowledge | ~200-1000 |
Integration
- Orchestrator Step 5 (DELEGATE): invoke before spawning teammate
- ralph-subagent-start.sh: reads
.claude/context-payload.md if exists
- Token budget: default 8000, adjustable per task complexity
Anti-Rationalization
| Excuse | Rebuttal |
|---|
| "The agent has enough context from the prompt" | Agents lose 40% accuracy without structured context. Package it. |
| "Context engineering is overhead" | 5 seconds of packaging saves 5 minutes of wrong output. |
| "I'll just include everything" | Token flooding degrades quality. Prune to signal. |
