Context Efficiency Patterns

Token budget management and context-aware prompt design — applies when prompts handle large inputs, long sessions, or need FinOps-efficient context loading.

Scope boundary: This skill covers context management (what to include, exclude, and how to structure input). For prompt structure patterns (XML sections, guards), apply prompting-guide. For prompt file mechanics (.prompt.md format), apply prompt-file-design.

The Context Budget Mindset

Think of context window as a budget, not a limit:

Golden rule: Every token should earn its place.

Pattern 1: Progressive Disclosure

Structure prompts to fetch detail incrementally:

<context_strategy>
PHASE 1 — Orientation (minimal context):
- Provide file structure / function signatures only
- Ask: "Which areas need deeper investigation?"

PHASE 2 — Targeted deep-dive:
- Fetch only the identified relevant sections

PHASE 3 — Synthesis:
- Work with focused, relevant context only
</context_strategy>

Pattern 2: Input Preprocessing

Tell the model HOW to handle large inputs:

<input_handling>
FOR LOGS:
- Skip repetitive entries (keep first + count)
- Focus on: errors, warnings, state transitions
- Ignore: debug spam, health checks

FOR CODE:
- Prioritize: signatures, class definitions, error handling
- Skim: boilerplate, imports
- Deep-read: business logic, custom implementations

FOR SEARCH RESULTS:
- Deduplicate similar findings
- Rank by relevance, summarize patterns
</input_handling>

Pattern 3: Relevance Boundaries

Explicitly scope what context matters:

<relevance_scope>
INCLUDE:
- Files in `src/modules/{module_name}/`
- Error messages containing "{pattern}"

EXCLUDE:
- Test files (unless debugging tests)
- Generated code in `*_generated/`
- Unrelated modules
</relevance_scope>

Pattern 4: Output Token Management

<output_efficiency>
RESPONSE SIZING:
- Simple questions → 1-3 sentences
- Code changes → diff-style or minimal replacement
- Analysis → structured summary

AVOID:
- Repeating the question back
- Explaining what you're about to do
- Including unchanged code around edits
- Verbose transitions
</output_efficiency>

Anti-Patterns: Context Waste