refactor: Tiered Context Management for Long Running Coding Sessions

[czha168]

Issue for this PR

I personally suffered from context rot. So here is the fix!
With this change, opencode can largely run autonomously for long period without suffering from context rot. No more spinning wheel for nothing and no more repetitive loop that leads to nowhere.

Oh, btw, opencode also run faster because of lightweight context. And it saves 30% on tokens too.

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

After a few hours of running opencode, it suffers from context rot. What I observed is opencode just spinning to nowhere, either with any response message or repetitive babbles that makes no sense, apparently brain dead.

The alternative to my change is to manually suspend opencode, /clear the context, and restart. And repeat a couple of hours later. Good bio breaks. But annoying still.

So, I implemented tiered memory for context management. Now, context rarely get filled over 80%.

With condensed context, opencode runs faster! A surprise for me. And of course it saves on tokens.

This clearly is not AI talking. This is a battle scared engineer and tenured architect typing with flesh hand.

If you paste a large clearly AI generated description here your PR may be IGNORED or CLOSED!

How did you verify your code works?

I have added test cases. It clearly shows context memory never exceeds 80%. From what I can gather, it generally condense memory by 30%.

Screenshots / recordings

Find a big project that will run overnight. Or better yet, runs for days. See how much this fix helps, yourself.

Checklist

• I have tested my changes locally. Yes, I used it personally. And I was very pleased. That's why I decided to contribute.
• I have not included unrelated changes in this PR

[github-actions]

Hey! Your PR title Tiered Context Management for Long Running Coding Sessions doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[czha168]

This is my first ever contribution on github. Let's hope it passes your review.

[rekram1-node]

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