fix(max): improve compaction

[skoob13]

Problem

The window compaction manager now only handles the single case: Inserting the summary message before the initiator human message. However, there are three cases in fact:

• The messages preserving the agent's trajectory are below 2000 tokens and 16 messages in total having the start message–perfect case. We should insert the summary message before the initiator message.
• The messages preserving the agent's trajectory are below 2000 tokens and 16 messages in total NOT having the start message–insert the context message and copy the initiator message to the end of sequence.
• The messages preserving the agent's trajectory cannot be used because it doesn't have an assistant or human messages or the sequence has too many tokens–insert the context message and copy the initiator message to the end of sequence.

Related trace

Changes

• Implement new logic.
• More tests.

How did you test this code?

Unit tests & manual testing

[greptile-apps]

_{6 files reviewed, no comments}

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[denakorita]

Looks good to me!

[kappa90]

lol, I've never seen this before