feat: implement smart pruning

[processtrader]

Summary

This PR implements Smart Pruning, a new context management system that replaces the basic FIFO approach with a tiered priority system to preserve critical information longer.

Key Changes

• Tiered Pruning: Tools are now classified into 3 tiers with separate token budgets:
  • Content (60k tokens): High value (read, webfetch) - Summarized when pruned
  • Navigation (15k tokens): Ephemeral (ls, grep) - Compressed when pruned
  • Action (Protected): Important (edit, write) - Never pruned
• LLM Summarization: Instead of deleting content entirely, pruned content is now replaced with concise (<100 token) LLM-generated summaries.
  • Uses the user's configured model or falls back to the provider's default "small model".
• Tool Compression: Navigation tools now gracefully degrade (e.g., grep keeps first 5 matches, bash keeps exit code + last 10 lines).
• Configuration: Added full configuration support in opencode.json for budgets, custom tool classification, and summarization settings.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search results, I found one potentially related PR:

Related PR Found:

PR #7049: "fix: clear tool output and attachments when pruning to prevent memory leak"
#7049

Why it's related: This PR deals with pruning mechanism and memory management, which is closely related to the context management improvements in PR #7215. While PR #7049 appears to be a bug fix for clearing outputs during pruning, your new smart pruning system likely supersedes or enhances this approach with the tiered priority system and LLM summarization.

The other results (PR #5422 on cache configuration and #1407 on autocompaction) are tangentially related to context optimization but don't appear to be direct duplicates of the smart pruning feature.

[github-actions]

Thanks for your contribution!

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