Why: Old tool results were filling the window, compaction could split a tool group or commit a stale summary, and reminders arrived as extra user messages.
Evidence: Compaction retries a conflict and opens the circuit after three failures; clearing keeps the last five tool results; a stale file write is rejected; RPC reports started, queued, or handled.
Impact: Requests over the context window replace older tool results with a placeholder. Rewriting an existing file now requires a read in the same run. Subagent text over 32000 characters is capped.
Refs: feature/context-engineering
Co-authored-by: Cursor <cursoragent@cursor.com>
Why: The library had no process entry, and the product backend still called the loop directly.
Evidence: go test -count=1 ./...
Impact: exec.Backend keeps the same request and result. Execute now goes through AgentSession. Extensions and packages are not a sandbox.
Refs: feature/pi-headless N6 N7
Co-authored-by: Cursor <cursoragent@cursor.com>