Agent-skills-standard common-context-optimization

Maximize context window efficiency, reduce latency, and prevent lost-in-middle issues through strategic masking and compaction. Use when token budgets are tight, tool outputs flood the context, conversations drift from intent, or latency spikes from cache misses. (triggers: *.log, chat-history.json, reduce tokens, optimize context, summarize history, clear output)

install
source · Clone the upstream repo
git clone https://github.com/HoangNguyen0403/agent-skills-standard
Claude Code · Install into ~/.claude/skills/
T=$(mktemp -d) && git clone --depth=1 https://github.com/HoangNguyen0403/agent-skills-standard "$T" && mkdir -p ~/.claude/skills && cp -r "$T/.agent/skills/common/common-context-optimization" ~/.claude/skills/hoangnguyen0403-agent-skills-standard-common-context-optimization && rm -rf "$T"
manifest: .agent/skills/common/common-context-optimization/SKILL.md
source content

Priority: P1 (OPTIMIZATION)

Manage the Attention Budget. Treat context as a scarce resource.

1. Observation Masking (Noise Reduction)

Problem: Large tool outputs (logs, JSON lists) flood context and degrade reasoning. Solution: Replace raw output with semantic summaries after consumption.

  1. Identify outputs exceeding 50 lines or 1 KB.
  2. Extract critical data points immediately.
  3. Mask by rewriting history to replace raw data with a summary placeholder.
  4. See
    references/masking.md
    for patterns.

See implementation examples for masking patterns.

2. Context Compaction (State Preservation)

Problem: Long conversations drift from original intent. Solution: Recursive summarization that preserves State over Dialogue.

  1. Trigger compaction every 10 turns or 8k tokens.
  2. Compact:
    • Keep: User Goal, Active Task, Current Errors, Key Decisions.
    • Drop: Chat chit-chat, intermediate tool calls, corrected assumptions.
  3. Format: Update System Prompt or Memory File with compacted state.
  4. See
    references/compaction.md
    for algorithms.

See implementation examples for compacted state format.

3. KV-Cache Awareness (Latency)

Goal: Maximize pre-fill cache hits.

  • Static Prefix: Enforce strict ordering — System -> Tools -> RAG -> User.
  • Append-Only: Never insert into the middle of history; append new turns only.

References

Anti-Patterns

  • No raw tool dumps: Mask large outputs immediately after extracting data.
  • No unbounded growth: Compact every 10 turns to preserve intent over dialogue.
  • No middle insertions: Append-only history maximizes KV cache hits.