fix(cli): compact before configured context threshold

[marius-kilocode]

Provider-reported token usage is only available after a response and can be missing or inaccurate, so the configured auto-compaction threshold could be crossed without compaction. Kilo could then send an oversized request and recover only after the provider returned a context-limit error.

This change estimates the assembled outgoing request before provider dispatch, including conversation text, system instructions, and tool schemas. It starts compaction when that estimate reaches compaction.threshold_percent or the existing reserved safety limit, whichever comes first, while retaining provider overflow handling as a fallback.

Preflight replay preserves media attached to the current user turn. Tool-result continuations skip proactive replay so completed tools are not executed twice, and conservative raw media accounting remains in place when capping output tokens.

Related user issue: #9605

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Overview

Both issues from the previous review have been resolved in the latest commits:

Previous Issue	Status
overflow.ts — Uint8Array payloads silently undercounted via JSON.stringify	✅ Fixed: now uses value.byteLength / 4 for binary payloads
compaction.ts — fragile pending heuristic for preflight replay detection	✅ Fixed: replaced with explicit overflow !== undefined sentinel semantics (false = preflight replay, undefined = disable replay)

The Uint8Array fix is covered by a new unit test at packages/opencode/test/kilocode/session-overflow.test.ts:248 that verifies a 600KB binary image registers raw > 100_000. The compaction semantics fix is validated by the assertion added to the preflight e2e test confirming marker.overflow === false.

Files Reviewed (5 files)

• packages/opencode/src/kilocode/session/overflow.ts — fix verified
• packages/opencode/src/session/compaction.ts — fix verified
• packages/opencode/test/kilocode/session-overflow.test.ts — new test added
• packages/opencode/test/kilocode/session-prompt-compaction-safety.test.ts — assertion added
• packages/opencode/test/kilocode/session-export/e2e.test.ts — network-dependent test removed

Fix these issues in Kilo Cloud

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_{Reviewed by claude-4.6-sonnet-20260217 · 853,271 tokens}

_{Review guidance: REVIEW.md from base branch main}